analysis of alternatives non-confidential report · 2016. 4. 20. · copy right protected –...

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ANALYSIS OF ALTERNATIVES

Non-confidential report

Legal name of applicant(s): MTU Aero Engines AG

Submitted by: MTU Aero Engines AG

Substance: Chromium trioxide, EC No: 215-607-8, CAS No: 1333-82-0

Use title: Functional chrome plating for aerospace applications for civil and military uses, comprising coating of new components for aircraft engines as well as maintenance, repair and overhaul work on aircraft engine components

Use number: 1


Use number: 1 Copy right protected – Property of MTU Aero Engines AG – No copying / use allowed.

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DISCLAIMER

This document shall not be construed as expressly or implicitly granting a license or any rights to use related to any content or information contained therein. In no event shall MTU Aero Engines AG be liable in this respect for any damage arising out or in connection with access, use of any content or information contained therein despite the lack of approval to do so.


Use number: 1 Copy right protected – Property MTU Aero Engines AG – No copying / use allowed.

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CONTENTS

SUMMARY .......................................................................................................................................................... 1

1. INTRODUCTION .................................................................................................................................................. 7 1.1. The substance ................................................................................................................................... 7 1.2. Uses of chromium trioxide at MTU .................................................................................................. 7 1.3. Purpose and benefits of chromium trioxide ...................................................................................... 8 1.4. MRO business in the aerospace sector ............................................................................................. 9

2. ANALYSIS OF SUBSTANCE FUNCTION.......................................................................................................... 10 2.1. Metallic chrome coatings .................................................................................................................. 10 2.2. Surface treatment process description “functional chrome plating” ................................................. 13 2.2.1. Pre-treatment processes (Etching / Pickling) ........................................................................................... 14 2.2.2. Functional chrome plating ....................................................................................................................... 15 2.2.3. Post-treatment processes .......................................................................................................................... 16 2.3. Key functionalities of functional chrome plating ............................................................................. 17 2.3.1. Key functionalities of chromium trioxide-based surface pre-treatment .................................................. 17 2.3.2. Key process and performance related functionalities of chromium trioxide based surface treatment

creating metallic chrome coatings .................................................................................................... 18 2.3.2.1 Application of partial coatings............................................................................................................... 19 2.3.2.2 Layer thickness / Rebuilding of parts .................................................................................................... 19 2.3.2.3 Wear resistance ...................................................................................................................................... 20 2.3.2.4 Hardness ................................................................................................................................................ 20 2.3.2.5 Corrosion resistance .............................................................................................................................. 20 2.3.2.6 Coefficient of friction ............................................................................................................................ 21 2.3.2.7 Possibility to coat complex parts ........................................................................................................... 21

3. ANNUAL TONNAGE............................................................................................................................................ 22 3.1. Annual tonnage band of chromium trioxide ..................................................................................... 22

4. OVERVIEW OF THE PROCESS FOR ALTERNATIVE DEVELOPMENT APPROVAL PROCESS FOR THE AEROSPACE SECTOR ........................................................................................................................... 23 4.1. General overview .............................................................................................................................. 23 4.2. Development and qualification ......................................................................................................... 26 4.2.1. Requirements development ..................................................................................................................... 26 4.2.2. Technology development ........................................................................................................................ 27 4.2.3. Qualification ............................................................................................................................................ 29 4.3. Certification ...................................................................................................................................... 30 4.4. Implementation / industrialisation .................................................................................................... 31 4.5. Implementation of alternatives for MRO purposes .......................................................................... 32 4.6. Possible impacts on flight security ................................................................................................... 33 4.7. Aircraft engine programme lifecycles .............................................................................................. 34 4.8. Examples for development and implementation of replacement technologies ................................. 36

5. IDENTIFICATION OF POSSIBLE ALTERNATIVES ......................................................................................... 38 5.1. Description of efforts made to identify possible alternatives ........................................................... 38 5.1.1. Research and development ...................................................................................................................... 38 5.1.2. Data searches ........................................................................................................................................... 40 5.1.3. Consultations ........................................................................................................................................... 41 5.2. List of candidate alternatives ............................................................................................................ 41

6. SUITABILITY AND AVAILABILITY OF CANDIDATE ALTERNATIVES .................................................... 42

CATEGORY 1 ALTERNATIVES ............................................................................................................................... 42 6.1. ALTERNATIVE 1: Thermal spray coatings: ................................................................................... 42 6.1.1. Substance ID and properties .................................................................................................................... 43 6.1.2. Technical feasibility ................................................................................................................................ 45 6.1.3. Economic feasibility ................................................................................................................................ 46 6.1.4. Reduction of overall risk due to transition to the alternative ................................................................... 47 6.1.5. Availability .............................................................................................................................................. 47 6.1.6. Conclusion on suitability and availability for alternative thermal spray coatings ................................... 47 6.2. ALTERNATIVE 2: Nickel and nickel alloy electroplating.............................................................. 47 6.2.1. Substance ID and properties .................................................................................................................... 47



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6.2.2. Technical feasibility ................................................................................................................................ 48 6.2.3. Economic feasibility ................................................................................................................................ 50 6.2.4. Reduction of overall risk due to transition to the alternative ................................................................... 50 6.2.5. Availability .............................................................................................................................................. 50 6.2.6. Conclusion on suitability and availability for alternative nickel and nickel alloy electroplating ............ 51 6.3. ALTERNATIVE 3: Chemical vapour deposition (CVD)................................................................. 51 6.3.1. Substance ID and properties .................................................................................................................... 51 6.3.2. Technical feasibility ................................................................................................................................ 52 6.3.3. Economic feasibility ................................................................................................................................ 54 6.3.4. Reduction of overall risk due to transition to the alternative ................................................................... 54 6.3.5. Availability .............................................................................................................................................. 54 6.3.6. Conclusion on suitability and availability for alternative CVD ............................................................... 54 6.4. ALTERNATIVE 4: Nanocrystalline cobalt phosphorus alloy coating ............................................. 55 6.4.1. Substance ID and properties .................................................................................................................... 55 6.4.2. Technical feasibility ................................................................................................................................ 55 6.4.3. Economic feasibility ................................................................................................................................ 57 6.4.4. Reduction of overall risk due to transition to the alternative ................................................................... 57 6.4.5. Availability .............................................................................................................................................. 57 6.4.6. Conclusion on suitability and availability for alternative nanocrystalline cobalt phosphorus alloy

coating .............................................................................................................................................. 57 CATEGORY 2 ALTERNATIVES ............................................................................................................................... 58

6.5. ALTERNATIVE 5: Electroless plating ............................................................................................ 58 6.5.1. Substance ID and physicochemical properties of relevant substances .................................................... 58 6.5.2. Technical feasibility ................................................................................................................................ 59 6.5.3. Economic feasibility ................................................................................................................................ 60 6.5.4. Reduction of overall risk due to transition to the alternative ................................................................... 60 6.5.5. Availability .............................................................................................................................................. 61 6.5.6. Conclusion on suitability and availability for alternative electroless nickel plating ................................ 62 6.6. ALTERNATIVE 6: Case hardening: carburising, carbonitriding, cyaniding, nitriding,

boronising ......................................................................................................................................... 62 6.6.1. Substance ID and properties .................................................................................................................... 62 6.6.2. Technical feasibility ................................................................................................................................ 62 6.6.3. Economic feasibility ................................................................................................................................ 63 6.6.4. Reduction of overall risk due to transition to the alternative ................................................................... 63 6.6.5. Availability .............................................................................................................................................. 63 6.6.6. Conclusion on suitability and availability for alternative case hardening ............................................... 63 6.7. ALTERNATIVE 7: Trivalent chrome plating .................................................................................. 64 6.7.1. Substance ID and properties / Process description .................................................................................. 64 6.7.2. Technical feasibility ................................................................................................................................ 64 6.7.3. Economic feasibility ................................................................................................................................ 65 6.7.4. Reduction of overall risk due to transition to the alternative ................................................................... 65 6.7.5. Availability .............................................................................................................................................. 65 6.7.6. Conclusion on suitability and availability for alternative trivalent chrome plating ................................. 66 6.8. ALTERNATIVE 8: Physical vapour deposition (PVD) ................................................................... 66 6.8.1. Substance ID and properties .................................................................................................................... 66 6.8.2. Technical feasibility ................................................................................................................................ 67 6.8.3. Economic feasibility ................................................................................................................................ 68 6.8.4. Reduction of overall risk due to transition to the alternative ................................................................... 68 6.8.5. Availability .............................................................................................................................................. 69 6.8.6. Conclusion on suitability and availability for alternative PVD ............................................................... 69 6.9. ALTERNATIVE 9: General laser coating technology ..................................................................... 69 6.9.1. Substance ID and properties / process description .................................................................................. 69 6.9.2. Technical feasibility ................................................................................................................................ 69 6.9.3. Economic feasibility ................................................................................................................................ 70 6.9.4. Reduction of overall risk due to transition to the alternative ................................................................... 70 6.9.5. Availability .............................................................................................................................................. 70 6.9.6. Conclusion on suitability and availability for alternative general laser coating technology .................... 70

PRE-TREATMENT ..................................................................................................................................................... 71 6.10. Mineral acids .................................................................................................................................... 71



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6.10.1. Substance ID and properties .................................................................................................................. 71 6.10.2. Technical feasibility .............................................................................................................................. 71 6.10.3. Economic feasibility .............................................................................................................................. 72 6.10.4. Reduction of overall risk due to transition to the alternative ................................................................. 73 6.10.5. Availability ............................................................................................................................................ 73 6.10.6. Conclusion on suitability and availability for mineral acids .................................................................. 73

7. OVERALL CONCLUSIONS ON SUITABILITY AND AVAILABILITY OF POSSIBLE ALTERNATIVES FOR FUNCTIONAL CHROME PLATING ...................................................................... 74

8. REFERENCE LIST ................................................................................................................................................ 76

APPENDIX 1 – MASTERLIST OF ALTERNATIVES WITH CLASSIFICATION INTO CATEGORIES 1-3 AND SHORT SUMMARY OF THE REASON FOR CLASSIFICATION OF ALTERNATIVES INTO CATEGORY 3 (SELECTION PROCESS) ....................................................................................................... 78

APPENDIX 2 – INFORMATION ON SUBSTANCES USED IN ALTERNATIVES ............................................... 80

APPENDIX 2.1 - ELECTROPLATING ALTERNATIVES (MAIN PROCESS) ....................................................... 80 APPENDIX 2.2 - PRE-TREATMENTS: MINERAL ACIDS ..................................................................................... 100

APPENDIX 2.3 – SOURCES OF INFORMATION .................................................................................................... 102

APPENDIX 3 – MTT 18 .............................................................................................................................................. 103



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List of Tables Table 1: Technical deficiencies of category 1 alternatives. ....................................................................................... 5 Table 2: Substance of this AoA. ................................................................................................................................ 7 Table 3: Examples on MTU specific metallic chrome coating applications. ........................................................... 10 Table 4: Key functionalities of chromium trioxide-based pre-treatment. ................................................................ 17 Table 5: Key functionalities of metallic chrome coatings for the assessment of alternatives for MTU’s purposes

(the table is non-exhaustive but covers the most relevant functionalities for evaluation of potential alternatives and alternative coatings). ......................................................................................................... 18

Table 6: Technology Readiness Levels-Overview (US Department of Defense, 2009). ......................................... 24 Table 7: List of alternatives categorised. ................................................................................................................. 41 Table 8: Comparison in process performance for nCoP and functional chrome plating (McCrea et al., 2003 and

Gonzales, 2010). ......................................................................................................................................... 55 Table 9: Material properties of nano Co-P alloys (McCrea et al., 2003 and Gonzales, 2010). ................................ 56 Table 10: Typical properties of electroless nickel-phosphorus coatings.................................................................. 59 Table 11: Technical deficiencies of category 1 alternatives for MTU’s purposes. .................................................. 75



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List of Figures Figure 1: Simplified overview of different steps that can be involved in functional chrome plating using

chromium trioxide at MTU ........................................................................................................................... 1 Figure 2: Illustration of the development, qualification, certification and industrialisation process required in the

aerospace sector (EASA; 2014, adapted)...................................................................................................... 3 Figure 3: Overview of MTU's know-how (MTU, 2016). .......................................................................................... 8 Figure 4: Civil Turbo Jet Engine V2500 for Airbus A320 (MTU Maintenance Hannover). ................................... 11 Figure 5: Functional chrome plated V2500 HPC rear shaft with metallic chrome coated layers (MTU

Maintenance Hannover). ............................................................................................................................. 11 Figure 6: Functional chrome plated V2500 stub shaft with partial metallic chrome coated layer (MTU

Maintenance Hannover).............................................................................................................................. 12 Figure 7: Bearing housing with partial plated hard chromium coating on the bearing seat (MTU Aero Engines

AG Munich). ............................................................................................................................................... 12 Figure 8: Functional chrome plated air cooling pipes against fretting fatigue (partial coating) (MTU Aero

Engines AG Munich). ................................................................................................................................. 13 Figure 9: Simplified overview of different steps that can be involved in functional chrome plating using

chromium trioxide at MTU. ........................................................................................................................ 13 Figure 10: Partial coating of an aircraft engine component (two bearing seats of a gear shaft). ............................. 19 Figure 11: Illustration of the qualification, certification and industrialisation processes (EASA, 2014,

http://echa.europa.eu/documents/10162/13552/aviation_authorisation_final_en.pdf(. .............................. 24 Figure 12: Illustration of the technology development and qualification process. (EASA, 2014,

http://echa.europa.eu/documents/10162/13552/aviation_authorisation_final_en.pdf, amended). .............. 29 Figure 13: Example to underline the importance of reducing residual risks in terms of aviation security. In this

case the fan disc and blades of the engine burst. As none of the slung off parts hit the airframe the airplane did not crash (NTSB). ................................................................................................................... 34

Figure 14: Lifecycle of a commercial engine programme. ...................................................................................... 35 Figure 15: Development and approval process in the aerospace sector. Examples from previous and ongoing

implementations are included. Loops indicate potentially iterative steps due to unsuccessful evaluation at the formulator or unsuccessful development. ......................................................................................... 37

Figure 16: Cross section of a typical thermal spray coating (TURI, 2006). ............................................................ 43 Figure 17: HVOF process (http://spray-molybdenum-wire.com/pic/spraying-molybdenum-wire/HVOF-spray-

molybdenum-wire.jpg, as of 10/19/15). ...................................................................................................... 43 Figure 18: HVOF thermal spraying onto a landing gear cylinder (Legg, 2001). ..................................................... 44 Figure 19: Nickel and nickel alloy electroplating process design (NDCEE, 1995). ................................................ 48 Figure 20: Typical CVD system (Legg, 2003a)....................................................................................................... 51 Figure 21: Microstructure of nano CoP coatings (Legg, 2003b). ............................................................................ 55 Figure 22: Electroless nickel plating (NDCEE, 1995). ............................................................................................ 58 Figure 23: Case hardening (NDCEE, 1995). ........................................................................................................... 62 Figure 24: Cross-section image from Cr(III) coatings in relation to layer thickness and to different spots located

at the coated part (pfonline, 2013). ............................................................................................................. 64



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Abbreviations

ACE Aerospace Chrome Elimination

ACF Airbus Chromate-free

Acute Tox. Acute Toxicity

Al Aluminium

AoA Analysis of Alternatives

Approx. Approximately

Aquatic Acute Hazardous to the aquatic environment

Aquatic Chronic Hazardous to the aquatic environment with long lasting effects

ASETSDefense Advanced Surface Engineering Technologies for a Sustainable Defense

ASTM American Society for Testing and Materials

Carc. Carcinogenicity

CAS Chemical Abstracts Service

CMR Carcinogenic, Mutagenic and Toxic to Reproduction

Cr(III) Trivalent Chromium

Cr(VI) Hexavalent Chromium

CSR Chemical Safety Report

CTAC Chromium Trioxide REACH Authorization Consortium

CVD Chemical Vapour Deposition

DLC Diamond Like Carbon

DoD Department of Defence

DT&E Development, Test and Evaluation

EASA European Aerospace Safety Agency

EC European Commission

e.g. exempli gratia, for example

EHS Environmental Health and Safety

ESTCP Environmental Security Technology Certification Program

EU European Union

FAA Federal Aviation Administration

Flam. Sol. Flammable Solid

HCAT Hard Chrome Alternatives Team

HV Vickers Hardness



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HVAF High Velocity Air Fuel

HVOF High velocity oxy-fuel

ID Inside Diameter

ISO International Organization for Standardization

Met. Corr. Substance or mixture corrosive to metals

MRL Manufacturing Readiness Level

MRO Maintenance, Repair and Overhaul

Muta. Germ cell mutagenicity

NASA National Aeronautics and Space Administration

NDCEE National Center for Energy and Environment

NSST Neutral Salt Spray Test

OEM Original Equipment Manufacturer

PECVD Plasma Enhanced Chemical Vapour Deposition

PTFE Polytetrafluoroethylene

PVD Physical Vapour Deposition

QPL Qualified Products List

R&D Research and Development

REACH Registration, Evaluation, Authorisation and Restriction of Chemicals

RoHS Restriction of Hazardous Substances

SDS Safety Data Sheet

SEA Socio Economic Analysis

Skin corr. Skin corrosion

Skin irrit. Skin irritation

Skin sens. Skin sensitisation

specs Standard of Specification

SST Salt Spray Test

STC Supplemental Type Certificate

SVHC Substance of Very High Concern

TNO Netherlands Organisation for Applied Scientific Research

TRL Technology Readiness Level

TSM Surface Treatment Mechanics, French company



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Glossary

Term Definition

Adhesion Parameter describes the tendency of dissimilar particles or surfaces to cling to one another (for example adhesion of coating to substrate, adhesion of paint to coating and/or substrate).

Alternative Potential alternative provided to the respective industry sector for their evaluation.

Bath Typical method for surface treatment of parts. May also be referred to as dipping or immersion. None-bath methods include wiping, spraying, and pen application.

Category 1 alternative Alternative considered promising, where considerable R&D efforts have been carried out within the different industry sectors.

Category 2 alternative Alternative with clear technical limitations which may only be suitable for niche applications and necessarily as general alternative in context with aircraft engines and MRO activities.

Category 3 alternative Alternative which has been screened out at an early stage of the Analysis of Alternatives and which is not applicable for the use defined here.

Chemical resistance Parameter is defined as the ability of solid materials to resist damage by chemical exposure.

Chromic acid

When brought in contact with water, chromium trioxide forms two acids and several oligomers: chromic acid, dichromic acid, and oligomers of chromic acid and dichromic acid. For the purpose of this document the terms chromic acid is synonymous with a mixture containing chromium trioxide and water. This is intended to be in line with ECHA Q&A #805.

Coating A coating is a covering that is applied to the surface of an object, usually referred to as the substrate. The purpose of applying the coating may be decorative, functional, or both.

Corrosion protection

Means applied to the metal surface to prevent or interrupt oxidation of the metal part leading to loss of material. This can be a metal conversion coating or anodising, a pre-treatment, electrolytic or electroless metal/metal alloy coatings, paint, water repellent coating, sealant, liquid, adhesive or bonding material. The corrosion protection provides corrosion resistance to the surface.

Counterpart Structural zone (like assembly, component) to which a given assembly/part is fitted.

Electroplating Electroplating is forming a metal coating on the part by an electrochemical method in an electrolyte containing metal ions and the part is the cathode, an appropriate anode is used and an electrical current is applied.

Etching

Process changing surface morphology as well as removing material. This is a pre-treatment step of the process chain preparing the surface before subsequent plating. This term has significant overlap with the term pickling. As there is no clear demarcation, the term etching is used to cover both etching and pickling as chromium trioxide pre-treatment in this document.

Functional chrome plating

An industrial use, meaning the electrochemical treatment of surfaces (typically metal) to deposit metallic chromium using a solution containing chromium trioxide (amongst other chemicals), to enhance wear resistance, tribological properties, anti-stick properties, corrosion resistance in combination with other important functional characteristics. Such secondary functional characteristics are chemical resistance, able to strip, unlimited in thickness, paramagnetic, deposit not toxic or allergic, micro-cracked brightness. Process characteristics are closed loop processing, high speed, flexibility in size, plating of inner surfaces, low process temperature, surface can be machined, assemblability. Functional chrome plating may include use of chromium trioxide in pre-treatment and surface deposits unlimited in thickness but typically between 2 µm and 500 µm. Functional chrome coatings are widely used in many industry sectors.

Implementation After having passed qualification and certification, the third step is to implement or industrialise the qualified material or process in all relevant activities and operations of production, maintenance and the supply chain.



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Term Definition

Legacy part

A legacy part shall mean any part of an end product which is manufactured in accordance with a type certification applied for before the earliest sunset date (including any further supplemental or amended type certificates or a derivative) or which is designed in accordance with a specific development contract signed before the earliest sunset date, and including all production, follow-on development, derivative and modification programme contracts, based on that development programme.

Main treatment The main treatment, functional chrome plating using chromium trioxide, occurs after the pre-treatment and before the post treatment.

Metallic chrome coating Resulting coating layer of the functional chrome plating process.

Pickling

Pickling is the removal of oxides or other compounds from a metal surface by chemical or electrochemical action. The term pickling is not used consistently within the surface finishing industry and is often referred to as the following processes: cleaning, scale removal, scale conditioning, deoxidising, etching, and passivation of stainless steel. This term has overlap with the term Etching.

Plating Electrolytic process that applies a coating of metal on a substrate.

Post-treatment Post-treatment processes do not involve chromium trioxide and are performed after the main functional chrome plating process.

Pre-treatment Pre-treatment process using chromium trioxide to remove contaminants (e.g. oil, grease, dust), oxides and scale. The pre-treatment process must also provide chemically active surfaces for the subsequent treatment. (See also: Etching).

Process chain

A series of surface treatment process steps. The individual steps are not stand-alone processes. The processes work together as a system, and care should be taken not to assess without consideration of the other steps of the process. In assessing candidate alternatives for chromium trioxide, the whole process chain has to be taken into account.

Qualification Original Equipment Manufacturer’s (OEM) validation and verification that all material, components, equipment or processes meet or exceed the specific performance requirements.

Temperature change resistance / heat resistance

The ability of a coating or substrate to withstand temperature changes and high temperatures.

Tribological properties Tribological properties relate to friction, lubrication and wear on surfaces in relative motion and are important for moving machine parts.

Wear resistance / abrasion resistance The ability of a coating to resist the gradual wearing caused by abrasion and friction.


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SUMMARY

Introduction This Analysis of Alternatives (AoA) forms part of the Application for Authorisation (AfA) for the use of chromium trioxide in functional chrome plating of aircraft engine components. Functional chrome plating at MTU is mainly applied during Maintenance Repair and Overhaul (MRO) activities for civil as well as military applications. Also it is applied in new (civil and military) engine parts, where MTU acts as an Original Equipment Manufacturers (OEM). These applications take place at the MTU sites in Munich, Hannover, Berlin and Rzeszow. 0.30 – 0.35 tonnes of chromium trioxide are used in functional chrome plating within the scope of this AfA per year.

Functional chrome plating using chromium trioxide is a surface treatment process that involves depositing a layer of metallic chromium on the surface of a metallic (e.g. steel, hardened steel, stainless steel, titanium alloys, nickel-/cobalt superalloys (cast and forged), copper alloys, and aluminium alloys) component. Typical applications of functional chrome plating include bearing systems, housings, shafts, gear drives and –wheels and hydraulic actuators. Metallic chrome coatings provides the article with high mechanical and wear resistance, excellent anticorrosion performance and a low coefficient of friction. Most importantly, only functional chrome plating with chromium trioxide offers the combination of all key functionalities that are mandatory to fulfil the demanding requirements of the aerospace sector. Functional chrome plating using chromium trioxide is therefore critical for aircraft engine components, which in general must perform under demanding conditions that involve extreme mechanical forces and temperatures as well as conditions that give rise to hot gas corrosion caused by sulphur and oxidation.

Surface treatment of metals is a complex and stepwise process. For the operation of high performance surfaces in demanding environments, the use of chromium trioxide in metallic chrome coating components is mandatory to ensure quality and safety of the final product over decades. As illustrated in Figure 1, there are two steps within the whole surface treatment process which involve the use of chromium trioxide: The pre-treatment process (for an adequate preparation of the substrate for the subsequently applied process steps), and the respective subsequent process step (main process). At MTU, there are no post-treatment processes for functional chrome plating which involve chromium trioxide. Although chromium trioxide is used in functional chrome plating processes, no chromium trioxide residues are present on the functional chrome plated article.

Figure 1: Simplified overview of different steps that can be involved in functional chrome plating using chromium trioxide at MTU

The characteristics of chromium trioxide, the plating process, and the key functionalities of the plated parts are discussed in detail in Chapter 2. MTU has specified the use of functional plating using chromium trioxide in order to meet the strict performance criteria necessary for regulatory



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compliance, public safety and customer expectations. These are described further below and in Chapter 4.

This AoA aims to explain why the use of chromium trioxide in functional chrome plating is essential for MTU’s purposes. It describes the steps and effort involved in finding and approving a replacement for chromium trioxide in these applications and evaluates potential alternatives in detail (Chapter 6 and 7).

Functional chrome plating of aircraft engine components with chromium trioxide Chromium has been used for more than 50 years to provide surface protection to critical components and products within several sectors where the products to which they are applied must operate to the highest safety standards, often in demanding environments, for extended periods of time. Functional chrome plating based on chromium trioxide has unique technical functions that confer substantial advantage over potential alternatives. For aircraft engine components at MTU these include:

- Excellent wear and abrasion properties combined with hardness; - Low coefficient of friction; - Corrosion protection; - Adequate layer thickness; - Ability to maintain lubrication due to micro-cracking; - Ability to plate complex parts and Inside Diameter (ID) surfaces; - Ability to plate defined areas of a part while the rest of the part remains uncoated.

These characteristics are essential to the safe operation and reliability (airworthiness) of aircraft, which operate under extreme environmental conditions. Aircraft engines are extremely complex in design, containing approximately 30,000 of highly specified parts, many of which cannot be easily inspected, repaired or removed. Most importantly, only functional chrome plating with chromium trioxide offers the combination of all key functionalities that are mandatory to fulfil the demanding requirements of the aerospace sector.

The chemistry behind chromium trioxide metallic chrome coatings and functional chrome plating processes is complex. Functional chrome plating is a specialist activity requiring trained personnel and a substantial investment in facilities. As described above, chromium plating processes typically involve several steps, often including a pre-treatment step as well as the main treatment process itself (see Figure 1). These steps are almost always inter-related such that they cannot be separated or individually modified without impairing the overall process or performance of the final product. Compatibility and technical performance of the overall system are primary considerations of fundamental importance during material specification. As of today, no drop in alternative for chromium trioxide in functional chrome plating, providing all the required properties to the surfaces of all articles in the scope of this application, is industrially available. Functional chrome plating using chromium trioxide has been successively refined and improved as a result of many decades of research and experience in the aerospace sector, and reliable data is available to support its performance. While corrosion cannot be totally prevented, there is also extensive experience, amassed over decades, on the appearance and impact of corrosion to support its effective management in these systems. On the other hand, data available so far for potential alternatives does not support reliable conclusions regarding their performance as part of such complex systems, in demanding environments and real-world situations. The long-term performance of such potential alternatives can currently only be estimated. Decreased corrosion protection performance would necessitate shorter inspection intervals and more substantial maintenance. Furthermore, the crucial role of every single part within an aircraft engine for flight safety has to be considered (Chapter 4.6).



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Ongoing development of potential alternatives for the aerospace sector Assuming a technically feasible potential alternative is identified as a result of ongoing R&D, extensive effort is needed beyond that point before it can be considered an alternative to chromium trioxide within the aerospace industry.

Aircraft are one of the safest and most secure means of transportation, despite having to perform in extreme environments for extended timeframes. This is the result of high regulatory standards and safety requirements. The implications for substance substitution in the aerospace industry are described in detail in a report prepared by ECHA and European Aerospace Safety Agency (EASA) in 2014 (http://echa.europa.eu/documents/10162/13552/aviation_authorisation_final_en.pdf), which sets out a strong case for long review periods for the aerospace sector based on the airworthiness requirements deriving from EU Regulation No 216/2008. Performance specifications defined under this regulation drives the choice of substances to be used either directly in the aircraft or during manufacturing and maintenance activities. It requires that all components, equipment, materials and processes incorporated in an aircraft must be certified, qualified and industrialised before production can commence. This system robustly ensures new technology and manufacturing processes can be considered ‘mission ready’ through a series of well-defined steps, which is only complete with the actual application of the technology in its final form (and under mission conditions). When a substance used in a material, process, component, or equipment needs to be changed, this extensive system must be followed in order to comply with airworthiness requirements. The system for alternative development through qualification, certification, industrialisation and implementation within the aviation sector is also mirrored in the defence sector.

The detailed process involved in qualification, certification and industrialisation, and the associated timeframes, are elaborated in Chapter 4.2. Of course, these steps can only proceed once a candidate alternative is identified. Previous experience indicates, it can take 20 to 25 years to identify and develop a new alternative, assuming that there are no complications during the various stages of development of these alternatives. Experience over the last 30 years already shows this massively under-estimates the replacement time for functional chrome plating using chromium trioxide. Taken together, available evidence shows that no viable alternative for all design spaces is expected for at least the next 15 years.

Figure 2: Illustration of the development, qualification, certification and industrialisation process required in the aerospace sector (EASA; 2014, adapted).

As a further consideration, while the implications of the development process in the aerospace sectors are clearly extremely demanding, specification of an alternative, once available, can be built into the detailed specification for new aircraft types (and new spacecraft). This is not the situation for existing aircraft types (e.g. Airbus 300, Boeing 747) with engines that may still be in production and/or operation.

MRO is a central concept in the aerospace sector and MRO service for aircraft engines is the main business at MTU. Airplanes are usually dimensioned to allow an overall lifetime of 20-30 years before

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they are finally taken out of service. It is the aim of the MRO activities to restore the original function of the equipment. In this regard, functional chrome plating is used at MTU to restore the full shape of the parts that have been distorted by abrasion, wear and tears, due to the demanding environments the engine parts are exposed to.

Production, maintenance and repair of existing engine models must be performed using the processes and substances already specified following the extensive approval process. Substitution of chromium trioxide-based plating for these aircraft introduces yet another substantial challenge: re-certification of all relevant processes and materials. Due to the sheer number of parts involved and engines in service, it can be can be considered impractical and uneconomical to introduce such changes (refer to Chapter 4.5).

The obligatory repair activities of aircraft engines must be conducted in accordance with the OEM’s specifications, as aircraft engines are highly complex systems where even small changes may have significant negative impacts on flight security that can even cause an airplane to crash (see chapters 1.4 and 4.6). The method for repair of the parts is also specified by the OEMs in the maintenance manual in the so called “service bulletins”. MTU as a component supplier does not decide on the actual repair methods.

In this context, the scale and intensity of industry- and company- wide investment in R&D activity to identify alternatives to chromium trioxide surface treatment systems is very relevant to the findings of the AoA. Equipped with major expertise, MTU also conducts serious research on coating technologies that could possibly be alternatives to functional chrome plating. Generally, efforts to find replacements for chromium trioxide have been ongoing within the aerospace industry for more than 30 years (chapter 5.1.1.).

For newly developed engines, newly developed MRO methods are theoretically plausible. But until all existing engines and airplanes are completely replaced, considerable time is needed until functional chrome plating is no longer necessary for aircraft engines, if ever.

Identification and evaluation of potential alternatives Extensive consultations and expert discussions were carried out in order to identify and evaluate potential alternatives to chromium trioxide in functional plating. A total of 9 candidate alternatives were identified. Here, a candidate alternative is defined as a potential alternative provided to the aerospace manufacturer for evaluation following initial evaluation by the formulator. These alternatives (including processes and substances) are either in use at MTU or focused on in ongoing R&D programmes and are examined in further detail in this report. 4 out of 9 alternatives were identified as promising alternatives, where considerable R&D efforts have been carried out (category 1 alternatives) and are discussed in Chapters 6.5 to 6.8.

Several potential alternatives are subject to ongoing R&D within the aerospace sector, but do not support the necessary combination of key functionalities to be considered technically feasible. As of today, none of these alternatives have all the key properties of functional chrome plating with chromium trioxide. In summary, this AoA shows that there are some promising alternative coating technologies. Some of these technologies are already in use at MTU, but not necessarily as an alternative to functional chrome plating. Thermal spray coatings are implemented as e.g. heat-insulating coatings, CVD coatings are mainly used as protective diffusion layers against high temperature corrosion and -oxidation. PVD coatings are used for e.g. aerospace wear applications (as erosion or anti fretting coatings in some aircraft engines). Clearly, these coatings are traditionally used in different application fields where metallic chrome coatings are not considered as they have a completely different microstructure than metallic chrome coatings.



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As of today, several technical limitations disqualify them from fully replacing functional chrome plating for MRO purposes. Table 1 summarises the main findings of the AoA for the use of chromium trioxide in functional chrome plating.

Table 1: Technical deficiencies of category 1 alternatives.

Alternative Reasons why alternative cannot replace functional chrome plating at MTU

1 Thermal spray coatings

- Not feasible for small IDs and complex geometries - Adhesion not in line with requirements - Wear resistance (depends on the coating, loads, wear mechanisms and the

counterparts) - Corrosion resistance (depends on the coating material) - Hardness (depends on technology and coating material)

2 Nickel and nickel alloy electroplating

- Hardness - Wear resistance - Coefficient of friction - Microstructure - No significant shift towards less hazardous substances

3 Thick CVD

- Partial coatings not feasible - Layer thickness insufficient for MRO - Process temperature - Geometry: size limitation, not suitable for large parts

4 Nanocrystalline cobalt phosphorus alloy coating

- Hardness - Wear resistance about 10 times lower compared to functional chrome plating - Partial coatings not feasible - No shift to significantly less hazardous substances - No experience with the alternative at MTU

Alternatives for the etching / pickling pre-treatment of low alloyed steel requiring chromium trioxide are assessed separately in Chapter 6.10. The development of a pre-treatment alternative to chromium trioxide depends on the potential alternative for functional chrome plating and is no standalone process. While an alternative for functional chrome plating is investigated, adequate custom-tailored pre-treatments are evaluated in parallel or after the potential alternatives for the main process has been qualified. Therefore, the time needed for R&D and industrial implementation of an alternative are identical for pre-treatment and main treatment which is a minimum of 15 years.

Review period Extensive evaluation of potential alternatives to chromium trioxide-based functional chrome plating, in aerospace applications for civil and military uses is carried out in the present AoA. Furthermore, economic aspects, as well as aspects of approval and release in the aerospace sector are assessed with regard to a future substitution of the substance. The following key points are relevant for derivation of the review period:

- Based on experience and with reference to the status of R&D programmes, implementation of feasible alternatives for key aircraft engine components and MRO applications at MTU is not foreseen to be finalised within 15 years after sunset date (Chapter 6).

- Any candidate alternative is required to pass full qualification, certification and implementation/industrialisation to comply with very high standards in the aerospace sector regarding airworthiness and flight security to ensure safety of use (Chapter 4).

- The European aviation industry in general requires optimal framework conditions in order to maintain its competitiveness, its high technological standards and to preserve/generate jobs. Long lifecycles of commercial engine programmes are linked to long investment cycles. Starting with the R&D kick-off of a new commercial engine programme, approximately 15 years, on average, are required to reach return on investment (ROI), while aircraft engine



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production periods may be more than 30 years. Maintenance and repair activities are required even after end of production (Chapter 4.7).

- The socio-economic impacts of a non-granted authorisation, amounting to € 1,221.6 million, outweigh the monetised residual risk to human health and the environment of a granted authorisation of € 76,894 (refer to the SEA).

As a consequence of the aforementioned circumstances, a review period of 15 years is selected because it coincides with best case estimates by MTU of the schedule required to industrialise alternatives to chromium trioxide.



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1. INTRODUCTION

1.1. The substance The following substance is subject to this AoA:

Table 2: Substance of this AoA.

Substance Intrinsic property(ies)1 Latest application date2 Sunset date3

Chromium trioxide, CrO3 EC No: 215-607-8 CAS No: 1333-82-0

Carcinogenic (category 1A) Mutagenic (category 1B)

21 March 2016 21 September 2017

1 Referred to in Article 57 of Regulation (EC) No. 1907/2006 ² Date referred to in Article 58(1)(c)(ii) of Regulation (EC) No. 1907/2006 3 Date referred to in Article 58(1)(c)(i) of Regulation (EC) No. 1907/2006

Chromium trioxide is categorised as a Substance of Very High Concern (SVHC) and is listed on Annex XIV of Regulation (EC) No 1907/2006. Adverse effects are evaluated in detail in the chemical safety report (CSR).

When brought in contact with water, chromium trioxide forms two acids and several oligomers: Chromic acid, Dichromic acid, oligomers of chromic acid and dichromic acid (further referred as "Chromic acids and their oligomers"). This AoA discusses many situations where this is the case. For the purpose of this document the terms chromic acid is synonymous with a mixture containing chromium trioxide and water.

1.2. Uses of chromium trioxide at MTU The processes with chromium trioxide for functional chrome plating applied at MTU are:

- Pre-treatment processes, such as etching/pickling of steel; - Main treatment process: applying a metallic chrome coating on specific substrates and

underplates to enhance wear resistance, tribological properties, anti-stick properties, and corrosion resistance in combination with other important functional characteristics.

These surface treatments are carried out for new parts and, even more importantly, for MRO purposes in the course of regularly performed obligatory maintenance work on aircraft as outlined in the maintenance plans. The MRO service is a main business for MTU. An overview MTU´s know how is illustrated in Figure 3.



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Figure 3: Overview of MTU's know-how (MTU, 2016).

The civil engine MRO business line accounts for 29% of the total turnover at MTU. Civil OEM accounts for 53% and military MRO/OEM for 14%. Of the total turnover, 4% is attributable to industrial gas turbines (IGT). IGTs, also known as aero derivative (AD) gas turbines, are based on aircraft engines, modified and commonly used for power generation or as compressor for oil and gas activities. However, only 10% of the IGTs for which MTU is offering MRO activities require chromium trioxide. Consequently this activity must be regarded as a niche application. The civil market is expected to increase as many new engines come into service, whereas the military market shows a stable decrease.

1.3. Purpose and benefits of chromium trioxide Using chromium trioxide has multifunctional positive effects, mainly based on the characteristics of the hexavalent chromium compound. It has been widely used for over 50 years in the industry in various applications. The multifunctionality of chromium trioxide provides important properties to the surfaces treated with the respective process. The following key functionalities for the aerospace sector are discussed in more detail in Chapter 2.3.

- Excellent wear and abrasion properties combined with hardness; - Low coefficient of friction; - Corrosion protection; - Adequate layer thickness; - Ability to maintain lubrication due to micro-cracking; - Ability to plate complex parts and ID surfaces; and - Ability to plate defined areas of a part while the rest of the part remains uncoated.

Most importantly, only functional chrome plating with chromium trioxide offers the combination of all key functionalities that are mandatory to fulfil the demanding requirements of the aerospace sector. Although chromium trioxide is used in functional chrome plating processes, no chromium trioxide residues are present on the functional chrome plated article.

Several alternatives are being tested to substitute chromium trioxide. The challenge is to find a substitute which meets the requirements for all different types of products, and for the different uses of each specific application that at the same time is technically and economically feasible. Many alternatives are now qualified for individual applications when some of the functional chrome plating requirements are sufficient but none has all the key properties of functional chrome plating with an aqueous solution of chromium trioxide.



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1.4. MRO business in the aerospace sector MRO is a central concept in the aerospace sector. Airplanes are usually dimensioned to allow an overall lifetime of 20 to 30 years before they are finally taken out of service. An aircraft engine is exposed to extreme mechanical forces and temperatures as well as to conditions that give rise to hot gas corrosion caused by sulphur and oxidation. Therefore the building components of aircraft engines are subjected to wear, corrosion, oxidation, vibrations and fatigue, as the required performance of the parts inevitably suffers and, if no adequate measures are taken, can be subject to failures. Moreover there are so called "life limited parts" that are deliberately operated above their yield strength, for example compressor and turbine discs and blades. Thus, in order to maintain flight security, aircraft are subject to intensive MRO activities.

Importantly, the disposal of “used” components and exchange for new parts is not common practice in the aerospace sector, as most of the parts are just too big and too expensive.

The MRO activities underlie national and international requirements that cover the different types of aircraft as well as specific components. The maintenance programme is strictly scheduled in the manufacturer’s maintenance manual that has to be officially approved by the authorities. The method for repair of the parts is also specified by the OEMs in the maintenance manual in the so called “service bulletins”. MTU as a component supplier does not decide on the actual repair methods. There are different maintenance activities foreseen after defined intervals of flight hours. Some are quite short (A-checks) but need to be conducted more often than others that are more labour and time extensive and need to be done after longer service periods (B, C and D checks). As an example, the so called D-check needs to be performed after six to ten years or about 25,000 flight hours. For the D-check, the whole aircraft is taken apart and almost every single part is checked for defects with a special focus on the engines. After several weeks and thousands of man working hours of intensive MRO work, the aircraft is overhauled completely. The D-check is the most extensive check foreseen for aircraft. In contrast to this, the smaller A-check needs to be done most often in the turn of about two months and are usually completed overnight.

In the maintenance business, MTU Maintenance is the world's largest independent provider of commercial engine MRO services in terms of sales and among the top five maintenance providers worldwide. The primary focus is on providing support for engines in which MTU is a risk- and revenue-sharing partner. MTU is the leading global provider of maintenance and repair services for the V2500, the engine powering the current Airbus A320 family as one of the most sold aircraft types in the world. MTU Maintenance also offers repair solutions for a wide variety of different engine types. Worldwide 150 airlines trust in MTU’s services with more than 14,000 engines repaired and overhauled.

Aircraft MRO is one of the core business services of MTU and accounts for about 38% of the company's total turnover; therefore MTU is especially focused on engine maintenance activities. It is the aim of the MRO activities to restore the original function of the equipment and components. In this regard, functional chrome plating is used at MTU to restore the full shape of the parts that have been distorted by abrasion, wear and tears, due to the demanding environments the engine parts are exposed to. Importantly, the repair treatments must be conducted in accordance with the OEM’s specifications, as aircraft engines are highly complex systems where even small changes may have significant negative impacts on the engine. In Chapter 4, more information is provided on the extensive development and approval procedures that are necessary to implement any changes in the aerospace sector and the consequences failures in this process may have on flight security.



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2. ANALYSIS OF SUBSTANCE FUNCTION

2.1. Metallic chrome coatings Metallic chrome coatings are usually applied in a layer with a thickness between 15 and 500 µm although the potential thickness of a metallic chrome coating is unlimited. Metallic chrome coatings generally form as a heavy layer resulting in high mechanical and wear resistance, with a high anticorrosion performance (with a nickel underplate for steel) and a low friction coefficient. They are usually used for technical applications such as industrial parts that must perform under demanding conditions comprising high temperatures, repetitive wear and impact forces.

Functional chrome plating is used in a number of different industries and the metallic chrome coating is predominantly applied on steel or hardened steel as substrate. Other substrates plated at MTU are stainless steel, titanium alloys, nickel-/cobalt superalloys (cast and forged), copper alloys, and aluminium alloys. Typical applications of functional chrome plating include bearing systems, housings, shafts, gear drives and -wheels and hydraulic actuators.

Some MTU specific examples of metallic chrome coating applications are provided in Table 3. As already explained, besides plating of new parts, functional chrome plating is mainly used by MTU for MRO work of aircraft engine components to restore the original state of the components as wear naturally occurs after a certain time of use.

Table 3: Examples on MTU specific metallic chrome coating applications.

Aerospace

- Control components - Jet turbine engine parts (rotating hardware such as bearings, shafts, rotors and smaller

hardware like fasteners) - Hydraulic actuators - Pins and axles - Wear pads, latches and bushes - Bearing systems - Bearing faces - Sealants (air, oil; for counter-rotating parts) - Accessories (hydraulic pumps) - Casings - Gear wheels - Pinion shafts - Gear shafts - Housings - HPT (High pressure turbine) disc shaft - HPT forward shaft - Shafts general - Spools and drums

Importantly, in these demanding environments corrosion occurs even in the highly developed chromium trioxide-containing coating systems used today. For the currently used coatings, extensive experience exists on the appearance and impacts of corrosion. Without a well-developed chromium trioxide-free alternative, corrosion will certainly increase, as these coatings do not offer all the crucial properties of chromium trioxide coating systems and their long-term performance can currently only be estimated. As a consequence, decreased corrosion protection performance may lead to shorter inspection intervals, which has a significant impact on the maintenance costs for aircraft. Furthermore, for secure adaptation of the inspection intervals a detailed knowledge of the alternatives



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is a prerequisite. Some examples for aircraft components that are functional chrome plated at MTU are illustrated in the following Figure 4 to Figure 8:

Figure 4: Civil Turbo Jet Engine V2500 for Airbus A320 (MTU Maintenance Hannover).

Figure 5: Functional chrome plated V2500 HPC rear shaft with metallic chrome coated layers (MTU Maintenance Hannover).



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Figure 6: Functional chrome plated V2500 stub shaft with partial metallic chrome coated layer (MTU Maintenance Hannover)

Figure 7: Bearing housing with partial plated hard chromium coating on the bearing seat (MTU Aero Engines AG Munich).

bearing seat



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Figure 8: Functional chrome plated air cooling pipes against fretting fatigue (partial coating) (MTU Aero Engines AG Munich).

2.2. Surface treatment process description “functional chrome plating” Surface treatment of metals is a complex and stepwise process. For the operation of high performance surfaces in demanding environments, the use of chromium trioxide for the treatment of aircraft engine components is mandatory to ensure quality and safety of the final product over decades. As illustrated in Figure 9, there are several steps within the whole surface treatment process which involve the use of chromium trioxide. These are classified into the pre-treatment process (for an adequate preparation of the substrate for the subsequently applied process steps), and the respective subsequent process step (main process). There are no post-treatment processes at MTU for functional chrome plating which involve chromium trioxide.

Figure 9: Simplified overview of different steps that can be involved in functional chrome plating using chromium trioxide at MTU.

It is of greatest importance that only the combination of adequate pre-treatment and the appropriate main process step leads to a well-prepared surface providing all of the necessary key requirements for the respective applications as described in detail in Chapter 2.3. Chromium trioxide is a pre-



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requisite for the main treatment of functional chrome plating to ensure high quality of the product and to meet the requirements of the industry.

Although single process steps can be assessed individually, they cannot be seen as stand-alone processes but as part of a whole process chain. Consequently, when assessing alternatives for chromium trioxide-based surface treatments, the whole process chain and the performance of the end product must be taken into account. While R&D on replacement technologies in surface treatments has been ongoing for decades, industry has only developed and qualified alternate treatments for a limited number of applications. Thus there are no universally applicable qualified alternate treatments available for all design spaces. At MTU, for etching of non-steel base materials (Al, Ni based or Ti-alloys) Cr(VI)-free processes are in use. However, it is crucial to consider the following points:

- In each case, the performance of the alternative materials/techniques must also - and even more importantly - be evaluated as part of the whole system;

- Any change of single steps in the process chain of surface treatments, will require component and/or system level test and evaluation, (re)qualification and implementation into the supply chain; and

- In fact, current approvals for most coating systems for the above mentioned parts (Table 3) still incorporate at least one layer prepared with a Cr(VI) compound, but mostly several process steps where Cr(VI)-based treatments are used current.

Therefore, for a thorough assessment of replacement technologies it is mandatory to include the whole process chain (including pre-treatment), taking into consideration that for all steps involved, chromium trioxide-free solutions must be developed, which in combination are technically equivalent to the current chromium trioxide containing treatments. As of today, complete chromium trioxide-free process chains are industrially available for some special applications only, where the performance criteria are comparably lower than the ones provided in Chapter 2.3. Also at MTU, several other technologies, as discussed in Chapter 6, are available and in use, but not necessarily as replacement technology for functional chrome plating with chromium trioxide.

For the functional chrome plated aircraft engine components in the scope of this AfA, at least one process step, usually the main treatment, requires chromium trioxide to provide the required properties to the surfaces. Currently, no complete chromium trioxide-free process chain is industrially available for aircraft engine key applications which provide all the required properties to the surfaces.

In general, all process steps are performed by immersing the product to be plated in a bath containing the process step specific aqueous solution. It is a wet-in-wet process, generally without any intermediate storage of the product at any time in the process chain, except for the final drying step.

If other substances are used for the pre-treatment process than chromium trioxide, numerous rinsing steps are necessary to prevent the carry-over of solutions from the pre-treatment bath to the functional chrome plating bath, as this might lead to interferences with the respective subsequent process step and can cross contaminate the plating bath.

A detailed description of the key performance parameters and the minimum requirements of the metallic chrome coating are provided in Chapter 2.3.

2.2.1. Pre-treatment processes (Etching / Pickling) A number of pre-treatments are necessary to prepare the surface of the substrates for the subsequent process steps. For example, for many parts of aircraft, only defined areas need to be functional chrome plated. For this purpose, the areas of the component that are to remain uncoated, are covered with wax, as shown in Figure 6 to Figure 8. However, only one pre-treatment involves the use of chromium trioxide, which is etching / pickling of steel. Adequate preparation of the base metal is a



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prerequisite: adhesion between the metallic chrome coating and the substrate depends on the force of attraction at a molecular level. Therefore, the surface of the metal – which is mostly steel for functional chrome plating – must be absolutely free of contaminants, corrosion and other residuals until the plating process is finished.

In general, there is not a clear demarcation between the processes of pickling and etching. When comparing specifications from different sources, the terminology is not always consistent from one document to another.

Pickling is the removal of stains, inorganic contaminates and oxides (as rust from a metal surface by a chemical or electrochemical process).

Pickling removes only the surface oxides and limited parts of the underlying substrate. For example, during a 5 minute pickling process, 0.4-0.6 µm of the substrate is removed. The removal rates vary for different substrates. Pickling removes less of the substrate material than etching. The metal parts are dipped in a bath containing the chromium trioxide-based pickling solution. The pickling is required as continuous oxidation during transport and manufacturing to generate a natural passivation layer, making the surface less reactive to the subsequent process steps.

Etching is defined as a surface activation step by removal of base material, from a metal surface.

Etching affects metal surfaces in a more aggressive manner than the pickling process. For example, during a 5 minutes etching step, 2-4 µm of the substrate is removed. The removal rates vary for different substrates. Etching is performed by immersing a metal substrate in an acidic solution (bath application). Some small amounts of metal may be intentionally removed by etching to facilitate inspection processes (e.g. nital etch (solution of alcohol and nitric acid), dye penetrant inspection).

As there is no clear demarcation, the term etching is used to cover both, etching and pickling as a chromium trioxide pre-treatment in the following. The vast majority of etching processes are reverse etching processes using an aqueous solution of chromium trioxide. The process is carried out in in a separate etch bath at MTU.

Mode of action: The purpose of etching is the removal of impurities (such as metal oxides) and a certain amount of the base metal from the substrate to achieve a micro roughened base metal surface of steels and stainless steels Chromium trioxide is necessary for controlling a moderate etch rate and to avoid over-etching. Additionally, an aqueous solution of chromium trioxide fulfils the following major purposes for the pre-treatment:

An aqueous solution of chromium trioxide acts as strong oxidising agent of the base metal and an acidified solution of chromium trioxide is also used to remove oxides from the surface. In both cases, the metal substrate is dissolved and can be removed from the system as sludge.

2.2.2. Functional chrome plating The metallic chrome coating layer is applied by electroplating based on the principle of electrolysis. An optional step prior to the electroplating is a Cu or Ni-strike which is applied in some cases for certain substrates. In this pre-step, a very thin layer of a fraction of a µm of Ni or Cu is applied to improve the adherence between substrate and metallic chrome coating. Additionally, thicker deposits of electroplated nickel may be used to improve the barrier corrosion performance of the coating.

Functional chrome plating is forming a coherent metal coating on the part to be plated (either the direct substrate or the substrate with already plated intermediate layers) by using the substrate as cathode and an inert anode (often platinum-coated titanium anode or tin-lead anode) and inducing an electrical current. The substrate is immersed in the electrolytic plating solution containing dissolved chromium trioxide and additives (electrolyte). During the electroplating process, the hexavalent chromium cations are reduced and build-up a metallic chrome coating layer (electrodeposition).



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Auxiliary electrodes or conforming anodes are placed near the substrate to ensure complete plating even on the inside or in hidden cavities of complex substrate surfaces.

In the plating process, solutions of chromium trioxide, with a concentration between 80 g/l and 400 g/l are used. Catalysts such as sulphuric acid are added in concentrations of 3 to 5 g/l. Additional catalysts contain mixed sulphate and fluoride ions and pre-prepared proprietary catalysts with each less than 2% of the content of chromium trioxide. The sulphate bath is a commonly used chromium trioxide bath and has an efficiency of approximately (approx.) 15%. Although fluoride or mixed catalysts baths have a higher efficiency than the sulphate bath (25%), their use is limited due to the chemical activity of fluoride ions which can attack the unplated surface.

Proprietary (organic) catalysts provide higher cathodic efficiencies of up to 25% and have the advantage not to attack the steel (unplated surface) in those areas of the cathodes where the current density is too low for chromium to be deposited. Proprietary catalysts are generally not used in the aerospace sector. Perfluorinated surfactants (such as perfluorooctane sulphonic acid, perfluorooctanoic acid or perfluorobutane sulphonic acid – perfluorinated compounds are currently evaluated by ECHA for restriction) are often added in ppm concentration (i.e. 2-4 ml/l) as mist suppressors to reduce chromic acid aerosol formation by bursting hydrogen bubbles on the solution surface, which are formed during the process. The bath temperature usually lies between 50 and 60°C. High temperatures (70°C) and solution additives reduce the number of cracks or can even eliminate them but simultaneously make the coating softer.

During the overall functional chrome plating process chain, numerous rinsing steps are carried out to prevent the drag-out of material from one plating preparation tank to the next. At MTU, the first rinsing step is carried out right above the chromium electrolyte tank in order to wash off the main content of the concentrated plating solution from the plated parts. Therefore the most chromium-acid concentrate is retained in the tank. Afterwards, rinsing is commonly performed by immersing the parts in a tank filled with rinsing (clean) water and usually occurs in several steps (cascade technology). The most common technique is counter-current cascade rinsing, where the part is rinsed in a succession of rinsing baths that are dedicated to the preparation or plating baths. Most of the process water is handled in a closed-loop system minimising wastewater streams by reuse of concentrated rinsing water in the process bath of the same type. Some water evaporates and must be replenished in order to keep the bath in balance.

For the remaining water used during the rinsing process, intensive waste water treatment is required and a number of different steps of wastewater treatment are known. The generated wastewater streams are cleaned from chromium trioxide residues in the rinsing water by the chemical reduction to Cr(III). This is achieved under acidic conditions using reducing agents such as sodium bisulphite or iron(II)sulphate. After being oxidised to trivalent iron, it serves as coagulant resulting in a precipitation with trivalent chromium in the sludge. This sludge is then disposed of. The cleaned wastewater has a chromium concentration far below the thresholds of the local wastewater regulation and can be discharged to the public wastewater system.

2.2.3. Post-treatment processes Post-treatments comprise rinsing and cleaning steps to remove potentially remaining process chemicals from the product and a final drying of the product as well as grinding, lapping, polishing or thermal treatment of the functional chrome plated substrate is performed. These post-treatments are chromium trioxide-free.

However, during the rinsing process minor amounts of the plating bath concentration are accumulated in the rinsing water. Process rinsing water can therefore contain minor amounts of chromium trioxide, but this is not relevant for the cleaning process itself. As mentioned above, the generated wastewater streams are cleaned from chromium trioxide residues in the rinsing water.



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2.3. Key functionalities of functional chrome plating An overview on the key functionalities of chromium trioxide in functional chrome plating is provided in the following chapters, subdivided into pre-treatment processes and the main coating process. Functional chrome plating can be applied on a variety of surfaces including but not limited to steels, stainless steels, nickel based alloys, copper alloys, aluminium alloys, titanium alloys, etc. During the consultations, the key functionalities for functional chrome plating as applied at MTU were identified taking the whole surface treatment processes into account. Nevertheless, the most important key functionalities of the high-quality final product are related to the chromium trioxide-based electroplating step that results in a high-end wear resistance and hardness of the coating.

2.3.1. Key functionalities of chromium trioxide-based surface pre-treatment The pre-treatment process prepares the surfaces for the subsequent main process step. In Table 4, selected key functionalities and relevant advantages for the pre-treatment process are listed and discussed in more detail below. With its optimal behaviour chromium trioxide based pre-treatment ensures high quality products and is the decisive factor for the use of the chromium trioxide based pre-treatment solutions.

Table 4: Key functionalities of chromium trioxide-based pre-treatment.

Process Key Process Functionality

Etching (Pickling)

Good control of etch rate (Etch rate: Steel: 0.25 µm/min/side, Chromium: 5 µm/min/side)

Minimal intergranular Attack / End Grain Pitting (ASTM F 2111)

Removal of residuals/oxides from the surface and micro-roughening

Corrosion resistance, adhesion of subsequent coatings

Minimum fatigue (ASTM E466) and tensile (ASTM E8) testing

Long-time bath stability if applied in a separate etch bath

Simple bath maintenance

Simple analytical method for process control

Etching (pickling) The key functionality of etching is the adequate removal of oxide and debris from a metal surface. For etching, selective removal of certain amounts of base material is required for surface activation. This process is controlled by the etch rate. The careful control of this step influences the quality of the subsequent coating layer.

After the pre-treatment, the processed parts will have a reduced number of pits, be free of corrosion products, discolouration, uneven etching, increased surface roughness or other defects that would prohibit further chemical processing (visual inspection, penetrant inspection (American Society for Testing and Materials (ASTM) E 1417)). The etching rate must be chosen according to the metal substrate used. Different types of steel require different etching rates. The longer and harder the etching, the greater the roughness of the surface.

Under-etching or over-etching should be avoided as not to affect the key functionalities of the subsequent coating (for example: poor adhesion resulting in cracks and blistering). The etch rate is controlled by measuring the thickness before and after processing.



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In addition, treated surfaces should be free of intergranular attack typically in excess of 5 µm or end grain pitting greater than 25 µm deep. Fatigue and tensile testing is performed according to ASTM E466 and ASTM E8. No degradation due to processing should be observed.

Further key functionalities are the long-term use of the plating solutions with proper maintenance. The bath chemicals have to be refilled ensuring dosing accuracy to prevent over- or under-etching. Additionally, the racks which the parts are applied to are usually used in the overall process chain and therefore have to be compatible with the chemicals used in the subsequent process steps.

2.3.2. Key process and performance related functionalities of chromium trioxide based surface treatment creating metallic chrome coatings

Selected (quantifiable) key functionalities of the metallic chrome coating applied on steel with (nickel) undercoat and deposited by the chromium trioxide functional chrome plating process are listed in Table 5 to give a short overview of the wide range of requirements. A more detailed description taking into account different substrates is given in the subsequent paragraphs.

Table 5: Key functionalities of metallic chrome coatings for the assessment of alternatives for MTU’s purposes (the table is non-exhaustive but covers the most relevant functionalities for evaluation of potential alternatives and alternative coatings).

Key functionality Definition / Justification Value

Application of partial coatings Applying the coating only where it is needed and where it is allowed to Not quantifiable

Layer thickness/ Rebuilding of parts

MRO: Required layer thickness depends on the grade of abrasion to be compensated to restore the original state

> 100 µm; can exceed 500 µm

Wear resistance ASTM D4060-10 < 50 mg/10,000 cycles

Hardness ISO 6507-1 800-1100 HV

Corrosion resistance* Neutral salt spray test (NSST) ASTM B117 ISO 9227

SST: > 750 h

Coefficient of friction ASTM D4518, ASTM D 1894

< 0.2

Possibility to plate complex parts Coating of small inner diameters and other complex shapes Not quantifiable

Please note that there are more requirements to functional chrome plating than listed above, for example, the ability of metallic chrome coatings to maintain lubrication due to the micro crack structure or machinability of the coated component. However, the ones listed above are the most significant functionalities that are used in the alternative assessment in Chapter 6. In the following paragraphs, the key functionalities are described in more detail.

As of today, only functional chrome plating with chromium trioxide offers the combination of all key functionalities that are required to fulfil the specifications of the aerospace sector. If an alternative does not provide the necessary combination of functionalities listed above, it cannot be considered as general alternative for aircraft engine components and MRO applications that are in the scope of this AfA.



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2.3.2.1 Application of partial coatings The application of partial coatings is the most important key functionality for MTU. There is actually no component that is fully functional chrome plated at MTU. Especially for MRO purposes it is of utmost importance that the coating can be applied exclusively and precisely to the surface area where the material is necessary to restore the original shape that was removed by abrasion and wear. Furthermore, there are areas on parts that for must not be coated at all. This applies for parts that are exposed to extremely high vibrational stress during service. Because of the vibrational stress any coating in those areas is prone to develop cracks on the surface. Due to the tight adhesion between the coating and the component material the cracks then spread into the parent material, which then of course is most likely to break. In terms of flight security, the risk of material fracture is indeed to be avoided. Therefore, it is crucial to have a method at hand that allows the generation of partial coatings as functional chrome plating does. In this case, the areas that are to remain uncoated are covered with a thick layer of wax. In the galvanic electroplating process, only bare metal areas are coated. Afterwards the wax can be removed easily by applying moderate heat to melt down the wax. For illustrative material the reader is referred to Figure 10.

Figure 10: Partial coating of an aircraft engine component (two bearing seats of a gear shaft).

2.3.2.2 Layer thickness / Rebuilding of parts The layer thickness has a high impact on the properties of the final metallic chrome coating, whereas thick deposits increase wear resistance and corrosion performance. Typical layer thicknesses have been identified to be >100 µm for the aerospace sector. This is especially important for the repair and restoration of worn aircraft parts in context with MTU’s MRO activities, where the layer thickness that is necessary to restore the original condition of the component can be up to 500 µm and more. A general value cannot be defined in this context, as it depends on the grade of wear that has to be compensated. Additionally, all functional chrome coatings are applied to the surface in a thicker layer than necessary and then grinded until the ideal thickness and a level surface are reached (see Figure 10).

There are several non-destructive methods available to determine the layer thickness, for example

- Magnetic method, ISO 2178 & ASTM D7091;



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- X-ray method, ISO 3497 & ASTM B 568; (However, this method is limited to smaller parts and cannot measure layer thicknesses exceeding 40 µm).

2.3.2.3 Wear resistance The wear resistance of a coating is generally tested via its sliding and abrasion resistance behaviour, although in the aerospace sector reciprocating sliding wear testing against materials used for counterparts is more common.

One commonly used test method is the Taber Abrasion test according to ASTM D4060-10. During this test, a rubbing material (such as a rubber wheel impregnated with abrasive particles) is rubbed over the coated surface with a defined force and for defined cycles. The distinct test procedure is company specific, but for all companies the requirement is that the coating shall not show any visually detectable damages after Taber linear abrasion (“no scratches”). General requirements stated in ASTM D4060-10 for metallic chrome coating applications are < 50 mg/10,000 cycles. A high wear resistance is for example especially important with regard to jet turbine engine parts, which are exposed to extreme stress and sliding friction which tends to result in fretting fatigue.

In the aerospace sector common wear resistance test methods are ASD PREN2132, electrodeposition of chromium for engineering purposes – aerospace series, pin-on-disk test, Falex block-on-ring test, gravelometer test and further tribological tests.

2.3.2.4 Hardness Hardness is defined as the resistance of solid matter to various kinds of permanent shape changes when a force is applied. The total hardness of the product is the combined result of the substrate hardness and coating hardness. Measuring Vickers hardness (HV) for metallic materials, ISO 6507-1, is the most common hardness test method. Extreme hardness of the metallic chrome coating is generally required for most functional chrome plating applications. For the use of functional chrome plating for aircraft components at MTU 800-1100 HV are required. Hardness is linked to the scratch and abrasion resistance.

2.3.2.5 Corrosion resistance Corrosion describes the process of oxidation of a metallic material due to chemical reactions with its surroundings, especially under the effect of humidity and oxygen. In this context, the parameter corrosion resistance relates to the ability of a metal to withstand gradual destruction by chemical reaction with its environment. As described above, aircraft engines are to a large extend exposed to conditions that induce corrosion.

Components that inhibit corrosion can be categorised according to basic quality criteria which are inhibitive efficiency and versatility. Ideally, the component is compatible with subsequent layers and performs effectively on all major metal substrates. Furthermore it needs to guarantee product stability (chemically and thermally) and reinforce the requested coating properties. The major corrosion resistance test performed for many sectors is the Salt Spray Test (SST) according to ASTM B117 and /or ISO 9227 in Europe (Neutral Salt Spray Test, NSST/NSS). Again, minimum requirements vary largely between sectors and applications.

The aerospace industry reported a minimum requirement of at least 750 h in neutral SST with no corrosion for functional chrome plated steel with a nickel underplate.



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2.3.2.6 Coefficient of friction Friction is the force resisting the relative motion of solid surfaces sliding against each other. The friction coefficient is low for functional chrome plated surfaces. The coefficient of friction can be determined by tribological testing.

ASTM D4518 is a test method for static friction of coating surfaces and ASTM D 1894 is the standard test method for static and kinetic coefficients of friction of sheeting.

The aerospace industry requires a lubricated coefficient of friction of < 0.2. Low friction and tribological advantages are required in the aerospace industry. In combination with wear resistance, these properties are especially required for critical parts in landing gear and hydraulics. Also important in this respect are the anti-stick properties, especially for hydraulic cylinders and shock absorbers, where a smooth starting movement is important.

2.3.2.7 Possibility to coat complex parts At MTU parts of different sizes and different geometries are functional chrome plated. Alternatives to functional chrome plating must be applicable for easily accessible geometries and areas such as outer diameters as well as for narrow and small geometries (such as small ID parts, see Figure 6 and Figure 7) which are difficult to access.



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3. ANNUAL TONNAGE

3.1. Annual tonnage band of chromium trioxide The annual tonnage band for the use of chromium trioxide in functional chrome plating is 0.35 tonnes per year.



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4. OVERVIEW OF THE PROCESS FOR ALTERNATIVE DEVELOPMENT APPROVAL PROCESS FOR THE AEROSPACE SECTOR

4.1. General overview Much has already been written about the airworthiness and approvals process in the aerospace industry in the document “An elaboration of key aspects of the authorisation process in the context of aviation industry“ published in April 2014 by ECHA and EASA (http://echa.europa.eu/documents/10162/13552/aviation_authorisation_final_en.pdf). The document makes a strong case for justification of long review periods for the aerospace sector. In this chapter we identify key points from the ECHA EASA “elaboration” document and add additional detail and justification for long review periods with specific regard to chromates.

Some of the key points identified in the “elaboration” document are:

- “The aerospace industry must comply with the airworthiness requirements derived from European Union (EU) Regulation No 216/2008 in Europe, and with similar airworthiness requirements in all countries where aeronautical products are sold.”

- “All components, from seats and galleys to bolts, equipment, materials and processes incorporated in an aircraft fulfil specific functions and must be certified, qualified and industrialised.” In addition the new materials must be developed and evaluated prior to these three steps.

- “If a substance used in a material, process, component, or equipment, needs to be changed, this extensive process [of development, qualification, certification and industrialisation] has to be followed in order to be compliant with the airworthiness requirements.”

- “Although the airworthiness regulations (and associated Certification Specifications) do not specify materials or substances to be used, they set performance specifications to be met (e.g. fire testing protocols, loads to be sustained, damage tolerance, corrosion control, etc.). These performance specifications will drive the choice of substances to be used either directly in the aircraft or during the manufacturing and maintenance activities.”

- The development (TRL (Technology Readiness Level) 1-6) process “is an extensive internal approval process with many different steps from basic technology research up to technology demonstration in a lab environment.”

- “Depending upon the difficulty of the technical requirements [qualification] can easily take 3-5 years. After initial laboratory testing, each specific application must be reviewed, which means additional testing for specific applications / parts. Airworthiness Certification begins at this same time, this certification can take from 6 months to years. Additional time is needed for production scale-up and development of a supply chain.”

Each one of these points is of significant importance for the aerospace sector with regards to chromates. Further elaboration will be made within this chapter.

The last bullet point highlights that it can take a significant period of time to develop and implement new alternatives. It should be noted that in the case of chromates, the stated time needed for taking an alternative from the development phase through qualification, certification and implementation has been significantly underestimated. Efforts to find replacements for chromates have been ongoing within the aerospace industry for over 30 years. In this time some successful substitutions have been made, but large challenges remain. Efforts thus far to identify equivalents for substances with critical, unique properties like corrosion inhibition have proven that there are no ‘drop-in’ replacement substances for chromium trioxide. Depending on the specific application and performance requirements many more years may be required before alternatives are identified and implemented.




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In this chapter the general process for alternative development through qualification, certification, industrialisation and implementation within the aviation sector is described. This process is followed closely by for civil and military uses. Because of the stringent requirements for qualification and certification a formal process for technology readiness and manufacturing readiness is followed.

The process for qualification, certification and industrialisation as described in the ECHA EASA “elaboration” document is shown in Figure 11.

Figure 11: Illustration of the qualification, certification and industrialisation processes (EASA, 2014, http://echa.europa.eu/documents/10162/13552/aviation_authorisation_final_en.pdf(.

This diagram is perhaps overly simplified and doesn’t indicate the significant level of research and development work required prior to qualification. As stated in the “elaboration” document “This process is an extensive internal approval process with many different steps from basic technology research up to technology demonstration in a lab environment.” The actual process followed by OEMs in the aerospace sector more closely follows the framework for TRLs and Manufacturing Readiness Levels (MRLs) originally developed by NASA. OEMs usually adapt this TRL/MRL approach resulting in individual versions which are considered proprietary and cannot be presented here. The NASA version is shown in Table 6.

Table 6: Technology Readiness Levels-Overview (US Department of Defense, 2009).

TRL# Level Title Description

1 Basic principles observed and reported Lowest level of technology readiness. Scientific research begins to be translated into applied R&D. Examples might include paper studies of a technology’s basic properties.

2 Technology concept and/or application formulated

Invention begins. Once basic principles are observed, practical applications can be invented. Applications are speculative, and there may be no proof or detailed analysis to support the assumptions. Examples are limited to analytic studies.

3 Analytical and experimental critical function and/or characteristic proof-of-concept

Active R&D is initiated. This includes analytical studies and laboratory studies to physically validate the analytical predictions of separate elements of the technology. Examples include components that are not yet integrated or representative.

4 Component and/or breadboard validation in laboratory environment

Basic technological components are integrated to establish that they will work together. This is relatively “low fidelity” compared with the eventual system. Examples include integration of “ad hoc” hardware in the laboratory.

5 Component and/or breadboard validation in relevant environment

Fidelity of breadboard technology increases significantly. The basic technological components are integrated with reasonably realistic supporting elements so they can be tested in a simulated environment. Examples include “high-fidelity” laboratory integration of components.

6 System / subsystem model or prototype demonstration in a relevant environment

Representative model or prototype system, which is well beyond that of TRL 5, is tested in a relevant environment. Represents a major step up in a technology’s demonstrated




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TRL# Level Title Description

readiness. Examples include testing a prototype in a high-fidelity laboratory environment or in a simulated operational environment.

7 System prototype demonstration in an operational environment

Prototype near or at planned operational system. Represents a major step up from TRL 6 by requiring demonstration of an actual system prototype in an operational environment (e.g., in an aircraft, in a vehicle, or in space).

8 Actual system completed and qualified through test and demonstration

Technology has been proven to work in its final form and under expected conditions. In almost all cases, this TRL represents the end of true system development. Examples include developmental test and evaluation (DT&E) of the system in its intended weapon system to determine if it meets design specifications.

9 Actual system through successful mission operations

Actual application of the technology in its final form and under mission conditions, such as those encountered in operational test and evaluation (OT&E). Examples include using the system under operational mission conditions.

In general the TRL assessments guide engineers and management in deciding when a candidate alternative (be it a material or process) is ready to advance to the next level. Early in the process, technical experts establish basic criteria and deliverables required to proceed from one level to the next. As the technology matures, additional stakeholders become involved and the criteria are refined. As specific applications are targeted as initial implementation opportunities, design and certification requirements are added to the criteria. Many more factors have to be taken into account prior to making a decision about transition of technology or replacing a material. A formal gate review process has been established by some companies to control passage between certain levels in the process.

A similar set of guidelines for MRLs exist for the management of manufacturing risk and technology transition process. MRLs were designed with a numbering system similar and complementary to TRLs and are also intended to provide a measurement scale and vocabulary to discuss maturity and risk. It is common for manufacturing readiness to be paced by technology or process readiness. Manufacturing processes require stable product technology and design. Many companies combine the aspects of TRLs and MRLs in their maturity assessment criteria as issues in either the technology or manufacturing development will determine production readiness and implementation of any new technology.

Referring back, now, to Figure 11: the general process steps can be loosely correlated to the steps in the TRL and MRL frameworks. Qualification begins after TRL 6 when technology readiness has been demonstrated. Certification begins around TRL 9 at the latest and may be performed in parallel with qualification. Industrialisation/Implementation are not tracked on the NASA TRL scale, but some OEMs refer to this phase as TRL 10. As previously stated, what is missing from the diagram, is the necessary and significant work that is performed before reaching technology readiness at TRL 6.

The whole development and qualification process is not only valid for the implementation of alternatives for new parts but also for any change that is to be introduced including the implementation changes in legacy parts for the MRO business. The following chapters describe the highlights of the entire process from definition of needs before technology development begins through to implementation. The emphasis here is to provide a description of the general process while highlighting the inherent complexities.

One additional point to keep in mind when reviewing the process description that follows is that there is no guarantee that the initial process to identify an alternative for a substance is successful. Failure



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is possible at every stage of the TRL process. The impact of failure can be significant in terms of time.

4.2. Development and qualification

4.2.1. Requirements development A need for a design change may be triggered due to many reasons. The one of interest here is when a substance currently used for production of aerospace parts is targeted for sunset (e.g. chromates). Completely removing one substance may impact various parts and systems on an aircraft and may involve many different processes with different performance requirements.

Once a substance is identified to be targeted by a regulation, a first step is to identify the materials and processes containing the specific substance. Most companies rely upon the information provided by the chemical manufacturer in the safety data sheet (SDS). This information source has many limitations when used for substance identification including: lack of reporting due to protection of proprietary data; reporting large concentration bands to protect specific formulary data; different disclosure requirements based upon country (articles exemption, thresholds, de minimis, specific substance classifications, etc.) to name a few. After identifying the materials and processes and associating these with specifications and other design references, parts are identified along with the applications and products which are potentially impacted. This is the first step in order to assess the impact for the company.

This work requires contributions from numerous personnel from various departments of an aerospace company like Materials & Processes, Research & Development, Engineering, Customers Service, Procurement, Manufacturing, Certification, including affiliates in other countries and Risk Sharing Partners.

Current production aircraft may have been designed 20 to 30 years ago (or more) using design methods and tools that are not easily revisited, nor were they necessarily standardised between OEMs. Checking and changing the drawings implies updating, e.g. creating the drawings under the new formats and tools, which can involve a tremendous amount of design work.

Note: When a new design is needed e.g. to remove a substance, it may not be compatible with the existing one, this means that spare parts designs of the original materials/configurations may need to be preserved in order to be able to produce spare parts for the aircraft using the original (baseline) configuration. This is an additional impact to be taken into account.

Once a substitution project is launched, technical specialists, from engineering and manufacturing departments, must define the requirements that the alternatives have to fulfil.

Alternatives must satisfy numerous requirements. In many cases requirements are identified that introduce competing technical constraints and lead to complex test programmes. This can limit the evaluation of alternatives. For instance, for some materials, dozens of individual engineering requirements with similar quantities of industrial requirements may be defined.

Categories of technical requirements may include:

- Materials and processes requirements (e.g. corrosion resistance, adhesion strength), - Design requirements (e.g. compatibility of the component’s geometry complexity and with

the coating application technique), - Industrial requirements (e.g. robustness and repeatability), - Environment, Health & Safety (EHS) requirements.

Definition of needs itself can be complex and requires significant timeframe. The complexity can be due to:



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- Different behaviour of the substitute compared to original product: new requirements may be defined. In this case, sufficient operational feedback to technically understand the phenomenon and reproduce it at laboratory scale is a must in order to be able to define acceptance criteria.

- Requirements may come from suppliers and have an impact on the design. - Constraints from EHS regulations evolution.

Once initial technical requirements are defined, potential solutions can then be identified and tested. The timeframe for initial requirements development can last up to 6 months. Note that requirements may be added and continue to be refined during the different levels of maturity.

4.2.2. Technology development The development process (typically TRL 4-6) is complex, and several years are often necessary before reaching development phase end (TRL 6). The following points explain why it may be long and complex:

- Developing solutions usually necessitates several testing phases before meeting the numerous requirements, which often induce several loops to adjust the formulation / design.

- Some tests are long lasting (e.g. some corrosion tests last 3,000h or longer). - In some cases, potential alternatives are patented, preventing multiple sources of supply,

which is an obstacle to a large supply-chain deployment due to increases in legal costs and in some cases a reduction in profitability for the business.

- When no 1 to 1 replacement solution is available, each alternative process must individually be considered to determine for which specific quantitative application it is suitable. This work represents a significant resources mobilisation, especially in term of drawings update and implementation of alternatives which due to the multiple work streams takes longer with higher costs. Moreover, spare parts and maintenance processes redesign may result in complex management both at the OEM and the Airlines. Additionally, substances regulations are evolving throughout the long research and development phase and life cycle of aircraft, which is another challenge for OEMs. There is a risk that significant investments could be made to develop and qualify alternative solutions involving substances with low EHS impacts identified at that point in time. Solutions may be developed and finally qualified, however, in the meantime, EHS constraints on those substances increased to a point where they now meet the SVHC criteria.

- When the suppliers have no “off the shelf” solutions, they must develop new ones considering a list of requirements that are often highly complex to combine (see the description of requirements in the above paragraph).

- Drawings impact: The replacement of a material / process may impact the complete design of a part. Additionally, the mating part/counterpart functionality must be analysed too (materials compatibility, dimensional compatibility, stress compatibility). This may lead to redesign of the complete part plus mating parts.

- Process instructions need to be developed.

The description of the development process is included in the qualification section of the ECHA EASA “elaboration” document. The text is reproduced here for continuity.

“Qualification precedes certification and is the process under which an organisation determines that a material, process, component or equipment have met or exceeded specific performance requirements as documented in a technical standard or specification. These specifications, often abbreviated as spec(s),



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contain explicit performance requirements, test methods, acceptance testing, and other characteristics that are based upon the results of research, development and prior product experience.

The industry relies upon standards issued by government-accredited bodies, industry or military organisations, or upon company-developed proprietary Standard of Specification (specs). Most materials and process specifications include either a “Qualified Products List” (QPL) or “Materials Control” section that identifies products that have met the requirements. Application and use of these qualified products must be assessed and certification implications addressed before being used on aircraft hardware.

OEMs rely upon the expertise of the chemical formulators to provide viable candidates to test against specific material and process specs.”

It is important to note that many iterations of these formulas are rejected in the formulator’s laboratory and do not proceed to OEM evaluation. Formulators estimate 2 to 5 years before candidates are submitted to OEMs.

“Once candidate(s) are developed, the OEM evaluates candidates by performing screening testing. If the candidate passes screening, testing is expanded to increase the likelihood that the preparation will pass qualification. If the candidate fails, which is often the case, material suppliers may choose to reformulate. It is not uncommon to iterate multiple times before a candidate passes screening. In some technically challenging areas, over 100 formulations have been tested with no success. This phase of development can take multiple years depending upon the material requirements. For those materials that pass screening, production scale-up, development of process control documents, manufacturing site qualifications, and extensive qualification testing is required to demonstrate equivalent or better performance to that which is being replaced. This phase of the process can also result in formulation or manufacturing iterations and may take several additional years. Depending on the complexity of the change and the criticality of the application (for example, fire protection or corrosion prevention have high safety implications and require development and testing against multiple, rigorous performance standards), re-certification may be required. The industry is ultimately limited by the material formulators’ willingness to expend their resources to develop alternative materials and technologies to be tested.”

The small volumes of materials sold, demanding performance requirements, and tightly controlled manufacturing processes for aviation customers provides an insufficient incentive for reformulation in some cases. When material formulators are not willing to reformulate their materials new sources need to be sought.



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Figure 12: Illustration of the technology development and qualification process. (EASA, 2014, http://echa.europa.eu/documents/10162/13552/aviation_authorisation_final_en.pdf, amended).

“This process [TRL 1-6 development] is an extensive internal approval process with many different steps from basic technology research up to technology demonstration in a lab environment. Depending upon the difficulty of the technical requirements, these initial steps can easily take 3-5 years. After initial laboratory testing, each specific application must be reviewed, which means additional testing for specific applications / parts. Airworthiness Certification begins at this same time, this certification can take from 6 months to years. Additional time is needed for production scale-up and development of a supply chain.”

It should be noted that the timeframes for development and qualification stated in the “elaboration” document have been combined and may be understated in the case of chromates. Depending on the application and the complexity of material and process requirements, this process can easily take multiple years. As noted in the “elaboration” document the timeframe for development alone is typically a minimum of 3 to 5 years. Our experience with replacement of the substance addressed in this dossier is that the development takes much longer. For typically successful projects the duration is 3 to 5 years. For unsuccessful projects the development goes through repeated iterations and has taken over 30 years and still continues with limited success.

4.2.3. Qualification Only after a technology has demonstrated technology readiness level 6, do the OEMs begin the qualification. All material, components, equipment or processes have to meet or exceed the specific performance requirements which are defined in the Certification Specifications documented in technical standards or specifications.

These are issued by military organisations, government-accredited bodies, industries or upon company-developed proprietary specifications. Products which have met all requirements are included in the documents as QPL or in the “Materials Control” section.

The main reasons for qualification are:

- To fulfil requirements by the Airworthiness Authorities European Aviation Safety Agency (EASA) and it is the first level of the aircraft certification pyramid.

- To ensure that only approved, reliably performing materials, parts and processes are used to produce aircraft components and systems.




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- To ensure that the product, the process or method is compliant with the industry regulations and aircraft manufacturer requirements to fulfil a specified function.

- To provide a level of confidence and safety. - To ensure consistent quality of products and processes. - To ensure supplier control, and to guarantee production and management system

robustness, throughout the supply chain.

The qualification process is mandatory to demonstrate compliance with airworthiness and certification requirements: the qualification process ensures that the technical and manufacturing requirements documented in the relevant material and/or process specifications are met. The qualification process comprises several steps before materials/processes are qualified. Even if most showstoppers are identified during the development phase, process confirmation/production verification are performed during the qualification phase. In case of failure, product qualification will be cancelled and the development phase must start again from the beginning.

Based upon OEM experience, the time period needed to pass the qualification process is estimated to be in the order of 8 years and can be even longer when major test failures occur. This is one of the main challenges for chromates replacement. Depending upon the materials, processes and criticality of the applications being evaluated, in-service evaluation and monitoring will be required and can extend to 15 years or more depending upon application.

4.3. Certification This next step is to certify that an aircraft and every part of it, complies with all applicable airworthiness regulations and associated Certification Specifications (specs). This step is also well described in the “elaboration” document and is reproduced here for continuity.

“Certification is the process under which it is determined that an aircraft, engine, propeller or any other aircraft part or equipment comply with the safety, performance environmental (noise & emissions) and any other requirements contained in the applicable airworthiness regulations, like flammability, corrosion resistance etc.

Although the airworthiness regulations (and associated Certification Specifications) do not specify materials or substances to be used, they set performance specifications to be met (e.g. fire testing protocols, loads to be sustained, damage tolerance, corrosion control, etc.). These performance specifications will drive the choice of substances to be used either directly in the aircraft or during the manufacturing and maintenance activities. Some examples of performance requirements are the following:

- Resistance to deterioration (e.g. corrosion) Environmental damage (corrosion for metal, delamination for composites) and accidental damage during operation or maintenance.

- Corrosive fluids - hydraulic fluids; blue water systems (toilet systems and areas); leakage of corrosive fluids/substances from cargo.

- Microbiological growth in aircraft fuel tanks due to moisture/contamination in fuel cause severe corrosion. Such corrosion debris has the potential to dislodge from the fuel tanks, migrate through the fuel system, and lead to an in-flight engine shutdown.

- Resistance to fire – flammability requirements fire-proof and fire-resistance. Aircraft elements are expected to withstand fire for a specified time without producing toxic fumes; this leads to using products like flame retardants, insulation blankets, heat protection elements in hot areas (e.g. around engines).

The primary certification of the aircraft (or engine and propeller) is granted to the manufacturer by the Competent Aviation Authority of the “State of Design” which is typically the authority of the state where the manufacturer of the aircraft (or engine or propeller) is officially located (EASA in the case of aircraft designed and manufactured in the EU and European Free Trade Association countries). Aircraft that are



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exported to other countries will have to be certified (validated) also by the authority of the “State of Registry”. Manufacturers work with the certification authorities to develop a comprehensive plan to demonstrate that the aircraft meets the airworthiness requirements. This activity begins during the initial design phase and addresses the aircraft structure and all systems in normal and specific failure conditions (e.g. tire failure, failure of structural components, hydraulics, electrical or engines). The tests needed to demonstrate compliance, range from thousands of coupon tests of materials, parts and components of the airplane, up to tests that include the complete aircraft or represents the complete aircraft (system). The performance and durability of the various materials have to be confirmed while the behaviour of the parts, components and the complete airplane will have to be tested in the applicable environmental and flight conditions including various potential damage or failure conditions. For a new Type Certificate this overall compliance demonstration covers several thousands of individual test plans of which some will require several years to complete. Often, after the initial issuance of the Type Certificate, the tests that have the objective to demonstrate durability of the aircraft during its service life, will continue.

All the different aspects covered by the Type Certificate together define the “approved type design” which includes, among other aspects, all the materials and processes used during manufacturing and maintenance activities. Each individual aircraft has to be produced and maintained in conformity with this approved type design.

Changes to the approved type design may be driven by product improvements, improved manufacturing processes, new regulations (including those such as new authorisation requirements under REACH), customer options or the need to perform certain repairs. When new materials or design changes are introduced, the original compliance demonstration will have to be reviewed for applicability and validity, in addition to a review of potential new aspects of the new material or design change that could affect the airworthiness of the aircraft. Depending on the change, this review could be restricted to coupon or component tests, but for other changes this could involve rather extensive testing. E.g. changes in protective coatings could affect not only the corrosion resistance but could also affect the friction characteristics of moving components in actuators in the different environmental conditions, changing the dynamic behaviour of the system, which in the end affects the dynamic response of the airplane.

Before the new material or design change can be introduced on the aircraft, all test and compliance demonstrations have to be successfully completed and approved by the Competent Authority. This approval results in the issuance of a Supplemental Type Certificate (STC), change approval or repair approval.

It is important to note that, according to the EU Regulation No 216/2008, EASA is the design competent authority for civil aircraft only. Any other aircraft (e.g. military, fire-fighting, state and police aircraft) will have to follow similar rules of the corresponding State of Registry.

To be able to maintain and operate an aircraft the responsible organisations must be approved by the competent authority and compliance is verified on a regular basis. Maintenance of an aircraft requires that the organisation complies with specific procedures and materials described in the maintenance manuals which are issued by and the responsibility of the OEMs.”

As noted in the “elaboration” document, in optimal cases certification can take as little as 6 months but typically will take several years. The duration really depends on the specific material and application.

4.4. Implementation / industrialisation An aircraft consists of several million parts which are provided by thousands of suppliers or manufactured internally by OEMs. Significant investment, worker training and manufacturing documentation may be required to adapt the manufacturing processes which sometimes require changes in existing facilities or the construction of new facilities.



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The industrial implementation is usually scheduled to follow a step wise approach to minimise the technical risks and benefit from lessons learned. This implies that the replacement is not implemented in all plants and at all suppliers simultaneously, but gradually. Each OEM may own several plants, e.g. up to 20 manufacturing sites / final assembly lines worldwide for some.

Furthermore, the implementation of an alternative process may induce new development and modification in the complete process flow.

The following text is reproduced from the “elaboration” document and describes the process for implementation of an alternative:

“Industrialisation is an extensive step-by-step methodology followed in order to implement a qualified material or process throughout the manufacturing, supply chain and maintenance operations, leading to the final certification of the aerospace product. This includes re-negotiation with suppliers, investment in process implementation and final audit in order to qualify the processor to the qualified process.

Taking into account that an aircraft is assembled from several million parts provided by several thousand suppliers, this provides an indication of the complexity for the industrialisation stage of replacement materials/processes, and the supply chain which provides these parts.

Special challenges are:

- Low volumes limit influence on changes to suppliers’ materials / processes; - Procurement & insertion of new equipment; - Scale-up & certification of new process; - Incompatibility of coatings could be a risk; - Re-negotiation of long term agreements with suppliers*; - Increased complexity of repairs – Multiple different solutions for different applications as a substitute

for a single, robust process. For example, currently all aluminium parts can be repaired with one chromated conversion coating. In some specific cases, the future state could require different conversion coatings for each aluminium alloy and application environment. Since different alloys are not easily distinguishable on the shop floor, ensuring that the proper repair procedures are used will be much more difficult. If alternate means of compliance approvals are requested for repair facilities or airlines, regulatory agencies are unlikely to have adequate knowledge or technical data to make informed assessments.

The operating environment, longevity of the aircraft, supply chain complexity, performance and above all airworthiness requirements are some of the considerations which can constrain the ability of the industry to make changes and adopt substitutes in the short, medium or long term.”

*Changes to the design or manufacturing may require re-negotiations with suppliers which can be time-consuming, especially when long-term contracts are concerned. The supply chain is complex in the aviation industry; it includes but is not limited to chemical manufacturers, importers, distributors, formulators, component manufacturers, OEMs, Airline operators, and aftermarket repair and overhaul activities. The timeframe for implementation and industrialisation is unknown. Simple changes may take 18 months to 5 years. The experience with replacement of the substance addressed in this dossier is that full implementation and industrialisation has yet to be accomplished. Implementation by airlines and Maintenance, Repair and Overhaul (MROs) further requires that an alternative is approved by the OEM and made available in the maintenance documents.

4.5. Implementation of alternatives for MRO purposes As described in Chapter 1.4, in the aerospace sector the methods for airplane MRO are evaluated and determined by the OEMs. When an alternative process is to be included in the maintenance documents, the challenges described above have to be faced out by the OEMs. As the repair method needs to be evaluated as part of the whole engine, for operating supplies and testing time frames,



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another 3 years may be necessary, depending on complexity of the alternative. For new engines this effort appears reasonable. However, for reasons of flight security changes in functioning aircraft engines, no matter whether new parts or new repair coatings are concerned, are avoided if possible. There are only two reasons for such a change in an existing engine system: either the occurrence of a severe damage on an operating part, which could compromise flight security, or an alternative method is significantly cheaper. The new method itself needs to be equal or better compared to the present one.

If a change in the MRO procedure is unavoidable or pursued for monetary reasons, at first the new coating needs to be developed on laboratory scale. The first step is followed by testing the deposition of the new coating on a part that simulates the precise component the alternative is supposed to be used for. The coated model part is further subjected to intensive experiments on a test bench, where the functional parameters (e.g. hardness, adhesion, wear, vibration resistance, corrosion and oxidation behaviour and others) are determined. If the alternative shows promising results, a prototype is made by coating an original component. The prototype is again examined in great detail on the test bench. Only if no issues occur at that stage, an original size floor drain engine is equipped with the new developed component. This is one of the most expensive stages, as the component is tested for several hundred hours in the floor drain engine, which comes along with huge fuel consumption. If the alternative also proves of value in this test, again scrupulous follow-up examinations are conducted. The examination data and reports have to be provided to the aviation authorities EASA and FAA (Federal Aviation Administration) to gain aviation approval. The whole procedure can take more than five years and cost several million euros. Additionally only one part can be exchanged from an engine in service at a time. As the interactions of complementary parts are very complex, changing more components, as it would be required when it comes to the elimination of chromium trioxide, is as elaborate as re-engineering the whole engine. Furthermore, for in-flight use of a changed aircraft engine, further security measures are taken. In an airplane that is equipped with four engines, at first only for one of them a “changed” engine is implemented to avoid serious incidents like a crash if the changed engine failed.

For these reasons changes in MRO methods cannot be implemented for full engines in service due to the sheer number of parts involved and engines in service. For newly developed engines also newly developed MRO methods are thinkable. However, the effort for detailed development and testing for each individual component cannot be avoided. Therefore considerable time is needed until functional chrome plating is not needed anymore for aircraft engines if ever. An overview on the long lasting development and approval process is outlined in Figure 15.

4.6. Possible impacts on flight security A further point to be mentioned in this context comprises the crucial role of every single part within an aircraft engine for flight safety. An aircraft engine is exposed to massive forces and extremely high stress levels due to high velocities and environmental impacts. Therefore, every single part needs to be designed and manufactured with serious attention and care. The parts in an aircraft engine need to be adjusted to each other very precisely on the planning as well as on the manufacturing level. For the development of completely new engines this is feasible but complex and time-consuming as described in the previous sections. As mentioned before, overhaul and repair activities are obligatory in the aerospace industry in defined intervals. This also includes the so-called D-Check, where the whole engine is taken apart and is overhauled completely. This might seem to be a good occasion to introduce variations of components. But, as described in the previous chapter, introducing a new part to an established engine is very complicated and bears high risks, as the interactions of complementary parts are very complex. Even a presumed improvement in one component is not necessarily beneficial for the whole engine. Changing one single detail of a part in an engine can have



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fatal consequences (Figure 13). Evaluation of the complex interplay of the complementary parts would need to be re-evaluated entailing long lasting approval and release periods.

Figure 13: Example to underline the importance of reducing residual risks in terms of aviation security. In this case the fan disc and blades of the engine burst. As none of the slung off parts hit the airframe the airplane did not crash (NTSB).

4.7. Aircraft engine programme lifecycles The overall lifecycle of a commercial aircraft engine programme, encompassing the research and development of an engine, its production and the in-service maintenance, spans decades. The initial development of a new aircraft engine may take up to 10 years. Aircraft engine production periods may be more than 30 years, while the typical lifetime of such an engine is 30 - 40 years. As mentioned above, airworthiness and approval processes in the aerospace sector are lengthy. Qualification, certification and implementation can easily take 10 or more years. Taking into account these very long timespans from developing to finally industrialising to production, investment cycles in commercial engine programmes are correspondingly constructed on a long term basis.



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Figure 14: Lifecycle of a commercial engine programme.



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In the first place, the development of new engines requires investments in R&D efforts. Once a newly developed engine enters into service, on average, approximately 15 years of service is required to reach return on investment (ROI) (Figure 14). The introduction of new substances or technologies in legacy and current aircraft types may require additional qualification, certification and industrialisation, thus adversely affecting the return on investment and therefore, long-term investments. Regarding MRO activities, this mainly refers to legacy (not in production anymore) and operating (still in production) aircraft types. Business decisions on the part of MTU regarding future engine programmes are consequently linked to risky investments due to uncertainties concerning the length of the review period. Therefore, a non-granted authorisation or even short review period puts at risk the return on investment of currently ongoing programmes and future investment decisions. Furthermore, for MTU it is necessary to take long-term decisions for being part of engine development and production programmes. Being part of such is essential to later on receive permission for subsequent MRO activities for the respective engine type. Granted MRO permissions by the engine OEMs allow secure future MRO activities, in turn financing future R&D activities for new engine programmes. For further information the reader is referred to the SEA.

4.8. Examples for development and implementation of replacement technologies In 2003, RoHS (Directive on Restriction of Hazardous Substances, 2002/95/EC) was adopted by the EU and took effect in July 2006. This directive triggered companies to substitute lead-based solder in electronic assemblies and all subsequent changes in the product designs and manufacturing processes: Basic research was started in the example company in 2003 with the selection and tests of alternative lead-free solder. The Research Programme was still running in 2014 and the qualification and industrialisation phase is ongoing: Components (IC’s, connectors, printed circuit boards etc.) had to be changed due to the higher soldering temperature that all materials have to withstand with lead-free solder and most of the manufacturing equipment had to be replaced. This fundamental replacement of lead (Pb) for aerospace and military applications with harsh environmental conditions will take more than 15 years in total to be deployed up to TRL9.

Work on a replacement for chromic acid anodise began in 1982. The initial driver for this R&D effort was to reduce emissions of hexavalent chromium and comply with federal and local clean air regulations. Initial requirements were identified and four candidate solutions were evaluated. One candidate solution was selected in 1984. Qualification testing began in 1985. A process specification for boric sulphuric acid anodising (BSA) was released in 1990. In 1991 and 1992 industrialisation began as several Boeing facilities began producing parts using the BSA process. One outside supplier also began processing parts to the Boeing specification in 1992. Evaluation of additional applications continued into the mid-1990s. In 2015, industrialisation of the BSA alternative for chromic acid anodise was still not complete. Many Boeing suppliers are shared with other OEMs and industries impeding the conversion to BSA from chromate acid anodising because they must continue to support multiple customer requirements. Note that for unprimed parts a dilute chromate seal is still required to provide required corrosion resistance. Work is ongoing to develop alternatives for this application. It is also worth noting that boric acid is now being proposed for REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) Annex XIV requiring authorisation. Should this happen alternatives may need to be developed for BSA. Other OEM solutions will need to be evaluated, qualified and certified by Boeing.

These examples are illustrated in Figure 15 on the following page.



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Figure 15: Development and approval process in the aerospace sector. Examples from previous and ongoing implementations are included. Loops indicate potentially iterative steps due to unsuccessful evaluation at the formulator or unsuccessful development.



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5. IDENTIFICATION OF POSSIBLE ALTERNATIVES

5.1. Description of efforts made to identify possible alternatives To prepare the authorisation of chromium trioxide, MTU purchased a Letter of Access (LOA) for the AfA from the CTAC Consortium (Chromium Trioxide Authorisation Consortium) of 150+ members. The aim of CTAC was to efficiently gather and analyse all necessary information for the three pillars of the authorisation dossier (CSR, AoA, SEA (Socio Economic Analysis)).

Therefore, the information used for assessing possible alternatives to chromium trioxide based functional chrome plating derive from the CTAC dossier as well as MTU´s efforts respectively.

5.1.1. Research and development As mentioned earlier in this document, a large amount of research over the last few decades has been commissioned to identify and develop viable alternatives to chromium trioxide. R&D is generally performed by specific companies by testing different plated products in feasibility studies. The unique set of functionalities of chromium trioxide are explained in detail in Chapter 2.3 and make chromium trioxide an ideal and not easily replaceable substance where high requirements with regard to hardness, wear resistance, corrosion, adhesion or friction, and fatigue properties have to be fulfilled to ensure safe performance in a demanding environment. Numerous research programmes were conducted funded by Europe clean sky (MASSPS, ROPCAS, LISA, DOCT, MUST, MULTIPROJECT) as well as programmes funded by United States Air Force (USAF) or other national funded programmes (e.g. LATEST in UK). Some key research programmes are listed below.

MTU activities MTU is an experienced user of functional chrome plating, as well as many other methods of surface treatment with and without chromium trioxide. Equipped with major expertise, MTU also conducts research on coating technologies that could possibly be alternatives to functional chrome plating such as CVD (see assessment of alternatives below).

A new project on alternatives for their chromium trioxide containing processes named “Functional Chromium replacementT12025” began in December 2015 in cooperation with R&D Institutes and universities including industrial platers. Within the next 10 to 15 years MTU will work on development and implementation of an environmentally and economically acceptable replacement process for thick chromium coatings from a new and nontoxic electrolytic solution. The coatings are expected to be as hard as and more resistant to corrosion than traditional coatings. The timeframe till technology readiness for first outcomes is planned to take four to five years within the 10 to 15 years mentioned above. The estimated budget for the project is € 1.5 - 2 million. A second project deals with alternatives to chrome conversion coatings which is subject to use 2 of this AfA.

Beside MTUs research and development activities, the company also invests in improvements of internal procedures. MTU developed and implemented a standard procedure (e.g. MTT 18 for the Munich site, see Appendix 3) for the internal approval and use of auxiliary materials, operating materials, filler materials, and hazardous materials for specific applications in development, production, repair and maintenance processes. If the materials to be approved are of the "very toxic", "toxic", "carcinogenic", "teratogenic" or "mutagenic" type, or classified as SVHC, no internal approval will be granted.



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Ecochrom The project Ecochrom on the “eco-efficient and high performance hard chromium process” is an Intelligent Manufacturing System-Growth project and has the objective to study and develop an environmentally and economically acceptable process allowing thick chromium coatings which are harder and more resistant to corrosion than traditional coatings, from a new and nontoxic electrolytic solution. Ecochrom is a consortium/working group of industrial platers, fundamental and applied researchers as well as end-users in Canada, USA, Japan and Korea, and is coordinated by TSM (Surface Treatment Mechanics), the main functional chrome plating specialist in France. The results of the Ecochrom project are still confidential.

The hard chrome alternatives team The Hard Chrome Alternatives Team (HCAT), is a US-Canadian collaboration of environmental working groups of the Departments of Defence of the two nations. They pursue the objective to demonstrate and validate that the alternative High Velocity Oxygen-Fuel (HVOF) is a superior alternative to functional chrome plating. Their efforts particularly focus on the aerospace industry and on military use. Increasing time intervals between maintenance and reduced turnaround times for repair of components would lead to a more sustainable performance. However, HCAT concluded that HVOF is not a generic alternative, neither technically (regarding temperature and geometrical limitations) nor economically (high costs).

Advanced surface engineering technologies for a sustainable defense The Advanced Surface Engineering Technologies for a Sustainable Defense (ASETSDefense) is a US Department of Defense (DoD) initiative sponsored by the department’s two environmental research programmes (Strategic Environmental Research and Development Programme and Environmental Security Technology Certification Programme (ESTCP)). Its objective is to facilitate the implementation of more environmentally friendly technologies for surface coatings and surface treatments. This initiative wishes to provide access to background information and technical data from research, development, test, and evaluation efforts as well as the status of approvals and implementations. ASETSDefense targets defence organisations and provides information to reduce environmental safety and occupational health impacts from coatings and treatment processes that utilise e.g. chromium plating from hexavalent solutions. The database providing information on the DoD´s data on authorisation and implementation of alternatives is readily accessible to the public (http://www.asetsdefense.org as of 08/06/14).

Airbus-chromate-free project The Airbus Chromate-Free (ACF) project was launched more than 10 years ago with the aim to progressively develop new environmental friendly Cr(VI)-free alternatives to qualified products and processes used in aircraft production and maintenance. Even prior to the launch of ACF, R&D efforts included the objective to remove chromium trioxide from use.

The ACF project is organised into several topics for the different fields of technologies affected by the replacement. ACF specifically addressed applications where chromates are used in production or applied to the aircraft; such as chromate acid anodising, basic primer, and external paints. In addition, sealants, chromate conversion coatings, passivation of stainless steel, passivation of metallic coatings or alternatives to hard chromium are included in the remit of this project. In synergy with ACF, an Airbus Group chromates replacement project is also in place.

Industry is not only working on one-to-one replacements for chromium trioxide applications but also reconsidering whole current coating systems. The significant investment in innovative coating technologies may lead successively to a stepwise change in the coming decades.

http://www.serdp-estcp.org/

http://www.asetsdefense.or/



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Highly innovative technology enablers for aerospace As an example, the Highly Innovative Technology Enablers for the Aerospace project was initiated in 2012 as a 17-member consortium consisting of aerospace OEMs, suppliers, paint application companies and academics with the goal of identifying and evaluating suitable alternative systems. In 2014, the tested alternatives are planned to reach TRL2. After the initial phase, the project will focus on a handful of promising alternatives and further testing will be undertaken within the next years- Completion of the research project was planned for 2015.

Amcoat: Potential replacements of Cr(VI) have been investigated in the comprehensive “Amcoat” project in the early 2000s. The project was accomplished by an industrial group of nine companies, electroplaters and component producers from the UK, Denmark, Germany and the Netherlands and was supported by two scientific institutes (University of Nottingham and Netherlands Organisation for Applied Scientific Research (TNO)).

The objectives of Amcoat were

- to develop Cr(VI) free plating solutions capable of depositing amorphous metal coating, - to demonstrate that electrodeposited amorphous coatings have at least equivalent surface

properties, like hardness, wear and corrosion resistance and, low friction, as metallic chrome coatings,

- to demonstrate that operating an industrial amorphous plating plant result in an overall reduction of health and safety hazards for the workforce, reduction of environmental discharges and that it is technically and economically feasible.

The project timescale was scheduled for more than two years. Although this project used significant combined interdisciplinary and international efforts, no alternative proved to be successful. The project failed. This example illustrates the enormous difficulties and challenges to find a suitable alternative for Cr(VI).

Indeed, on the basis of the aforementioned unique properties and diverse functionalities of chromium trioxide and the multiple process step coating systems, alternatives have to be identified and implemented into all process steps to be completely chromium trioxide-free.

Aerospace Chrome Elimination (ACE) The ACE team is comprised of material and process (M&P) engineers from U.S. aerospace companies and DoD (U.S. Department of Defense – Army, Navy, Air Force) that was formed over 25 years ago (1st meeting held in 1988) with the sole purpose to work together to identify replacements for processes used in the aerospace industry that contain or use materials that contain hexavalent chromium. The processes targeted by the ACE team are as follows: conversion coatings, anodise, anodise seals, paint primers, alkaline cleaners, titanium processing, sealants, adhesive bonding surface preparation, and chrome plating. The group meets in person once a year and has 3 virtual meetings per year. For chrome plating, the best alternative selected has been HVOF thermal spray with WC-Co or WC-Co-Cr but this is not a drop-in replacement because it is a line of sight spray process that cannot do certain complex geometries such as the inside diameter (ID) of tubes.

5.1.2. Data searches As a basis for this AoA, the documents derived by the CTAC consortium were purchased via a LoA. For the elaboration of this AoA, extensive literature and test reports were provided by the technical experts from MTU for adaptation and refinement of the document to the specific purposes of the company. Furthermore, searches for publically available documents were conducted to ensure that all



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potential alternate processes to chromium trioxide-containing applications were considered in the data analysis.

5.1.3. Consultations Consultations and expert discussions were conducted to get an overview on the completeness and experience with the alternatives, completeness and prioritisation of critical parameters for their specific processes and the technical requirements. During the consultations, additional alternatives have been identified and included in the list of alternatives. Some alternatives were screened out after intensive discussions within MTU based on confirmation that they are not applicable for the use defined within this AfA.

Verification of data and the collection of further detailed quantitative information was ensured in active and constant exchange of expertise. Moreover, site visits were carried out. Discussions with technical experts, followed by a final data analysis led to the formation of a list of alternatives divided into 3 categories, according to their potential to be suitable for the specific use.

In summary, the categorised table of alternatives listed below is the outcome of extensive literature, in house research and consultations with technical experts in the field of surface treatment.

5.2. List of candidate alternatives The most promising alternatives for chromium trioxide in functional chrome plating (Table 7) are assessed in detail in the following Chapter 6, the category 3 alternatives are listed in Appendix 1.

According to their relevance, the potential alternatives are classified as Category 1 (focused in the dossier, relevant R&D on these substances ongoing) or Category 2 (clear technical limitations, may only be suitable for niche applications but not necessarily as general alternative in context with aircraft engines and MRO activities).

Table 7: List of alternatives categorised.

Category No. Candidate Alternative

Category 1 alternatives 1 Thermal spray coatings


3 Thick chemical vapour deposition (CVD)


Category 2 alternatives

5 Electroless nickel plating

6 Case hardening: carburising, carbonitriding, cyaniding, nitriding, boronising

7 Trivalent hard chromium

8 Physical vapour deposition

9 General laser and weld coating technology

Pre-treatment 10 Mineral acids



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6. SUITABILITY AND AVAILABILITY OF CANDIDATE ALTERNATIVES

To assess the feasibility of the alternatives, colour-coded summary tables are included in the document. The colours are as follows:

The alternative assessments each comprise a non-exhaustive overview of substances used with the alternatives and alternative processes as well as the risk to human health and environment. These tables are provided in Appendix 2.

As of today, only functional chrome plating with chromium trioxide offers the combination of all key functionalities that are required to fulfil the specifications of the aerospace sector. If an alternative does not provide the necessary combination of functionalities listed in Chapter 2.3, it cannot be considered as general alternative for aircraft engine components and MRO applications that are in the scope of this AfA.

CATEGORY 1 ALTERNATIVES

The technologies and processes assessed in this chapter are considered the most promising, and those for which considerable R&D efforts are being carried out within the aerospace sector and at MTU. They either show technical limitations when it comes to the demanding requirements, such as wear resistance, corrosion performance and/or have economical disadvantages at the current stage. However, some of these technologies are already used in certain applications at MTU, but not as a general alternative to functional chrome plating. There are no universally applicable qualified alternate treatments available for all design spaces. Note that the list of substances provided for each alternative is extensive but not conclusive.

6.1. ALTERNATIVE 1: Thermal spray coatings: There are five general types of thermal spray processes in order of increasing coating quality which have been mentioned during the consultation phase:

- Flame spraying (including wire flame spraying, powder flame spraying); - Cold Gas Spraying; - (Wire) Arc spraying; - Plasma spraying; and - High velocity oxy-fuel spraying (HVOF).

From MTU’s experience, these processes show in principle the same technical performance and are therefore assessed together in this chapter. All of these processes are applied at MTU for special applications that are not in the scope of this dossier (heat-insulating coatings, flanges, abradables) as they do not require the combination of all key functionalities as described in Chapter 2.3.

Colour Explanation

Not sufficient – the parameters/assessment criteria do not fulfil the requirements

The parameters/assessment criteria fulfilment not yet clear/ fulfil some requirements for some but not all applications

Sufficient – the parameters/assessment criteria do fulfil the requirements

No data available



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6.1.1. Substance ID and properties Thermal spray processes offer a large choice of possible starting powders (pure metals, alloys, and carbides), gases, types of equipment, coating materials and deposition conditions and are therefore very versatile in their application area. Basically, in thermal spray coatings the coating particles are accelerated to high speed. Then the particles are melted by a supersonic flame (as in HVOF) or plasma beam (as in plasma spraying). When hitting the substrate surface the melted particles flatten to pancake-shaped “splats” and they all form a typical coating as shown in Figure 16. As the splats overlay each other, they form a very coherent and low porosity coating (Legg, 2003a).

Out of the list of possible substances used in plasma spraying processes, tungsten carbide (WC-Co and WC-CoCr), Mo, CoCrMo and chromium carbide-nickel chromium (Cr3C2-NiCr) showed promising results during R&D and/or are already applied for niche applications. Therefore, the technical feasibility assessment presented in the following focuses on these substances.

Figure 16: Cross section of a typical thermal spray coating (TURI, 2006).

HVOF For HVOF a gun equipped with an internal combustion chamber is used. In the chamber the combustion fuels are mixed with oxygen and fired continuously. Examples for combustion fuels include propylene, acetylene, propane, hydrogen and kerosene. These gases mixed with oxygen produce gas temperatures exceeding 2,700°C when burned. The coating powder is injected axially into the flame where it heats and softens on its way to the substrate surface. The distance between the gun and the substrate has to be sufficient (15-30 cm) in order to heat the particles adequately before they hit the substrate (Legg, 2003a). Figure 17 shows the basic principle of the HVOF-process.

Figure 17: HVOF process (http://spray-molybdenum-wire.com/pic/spraying-molybdenum-wire/HVOF-spray-molybdenum-wire.jpg, as of 10/19/15).

http://spray-molybdenum-wire.com/pic/spraying-molybdenum-wire/HVOF-spray-molybdenum-wire.jpg

http://spray-molybdenum-wire.com/pic/spraying-molybdenum-wire/HVOF-spray-molybdenum-wire.jpg



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Figure 18 shows the coating process of a landing gear cylinder that is conducted in a booth and air cooling jets (pipes in the upper right corner) to maintain a low surface temperature.

Figure 18: HVOF thermal spraying onto a landing gear cylinder (Legg, 2001).

HVOF coatings offer the highest quality within thermal spray processes because of the high speed of the particles. High Velocity Air Fuel (HVAF) is an HVOF-related process that uses air as oxygen source, avoiding the need for compressed bottle oxygen.

Plasma spraying: Plasma spraying is a thermal spray process and uses highly energetic plasma as a heat source instead of fuel and oxygen as in HVOF. The plasma is formed by generation of high density arc current in the space between cathode and anode that is filled with gases such as hydrogen or argon. The gas is ionised, heated up to 15,000°C and focused as a beam towards the workpiece. Despite of the high gas temperatures, the surface temperature of the workpieces during deposition is between 150 and 400°C. The microstructural properties of the coating are determined by the properties of the plasma stream. These depend on nozzle geometry, type of gas and electric arc settings. In wire arc spraying an electric arc serves both as heat source and as the source of molten metal droplets that are transported via a gas jet to the substrate surface.

Cold gas spraying: The coating particles are accelerated to high speed by an ultra-high velocity gas stream. When they hit the surface they soften and melt through a conversion of kinetic to thermal energy. To date, cold gas spraying is only suitable for depositing low melting point metals (e.g. Cu and Al). Also, the process is still limited to ductile materials such as Al, stainless steel, titanium and alloys (Legg and Sauer, 2000).

Flame spraying is a simple thermal spray method for lower quality alloy coatings. The coating powder is injected into a gas jet and fed through a flame. The compressed air is used to atomise the molten metal and accelerate the particles onto the substrate. In general, the coating is of poor quality (porous and low adhesion) and therefore not suitable as an alternative to functional chrome plating.

Besides the mode of application, the material used in the process significantly influences the properties of the thermal spray coating. Therefore, the most promising materials for thermal spray coatings are illustrated in the following assessment of the technical feasibility, which are WC-Co, WC-Co-Cr and WC-Cr-Ni based on R&D. General information of the exemplary chosen tungsten



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carbide cobalt coating and the risk to human health and the environment is provided in Appendix 2.1.1. Hereinafter, HVOF, plasma spraying arc, cold gas, and flame spraying are referred to as “thermal spray processes” if addressed together.

6.1.2. Technical feasibility Wear resistance: Concerning wear resistance and endurance, the performance depends on coating material, load, the respective counterpart, velocity and lubrication. In some situations the alternative is superior to metallic chrome coatings, but in general, no alternative coating using this technology is equivalent in all situations.

Hardness: Hardness performance of thermal spray coatings strongly depends on the technology and coating material applied. In terms of hardness, coatings based on WC-Co have are equivalent to metallic chrome coatings. Other coatings such as Mo and CoCrMo are softer (> 400HV). Compared with the other thermal spray coating technologies, HVOF shows superior hardness performance.

Geometry of coated parts: As a line-of-sight process, thermal spraying is limited in terms of coating complex shapes and inner surfaces. The problem is that a minimum gun-to-substrate distance (stand-off) is required to achieve softening and acceleration to high velocity of the powder. The geometry influences directly and strongly the deposition velocity, which decreases with increasing complexity. Furthermore, the spray gun is supposed to be directed onto the surface in a 90 ° angle. In small inner diameters an adequate spraying angle cannot be achieved. These limitations indicate that thermal spray coatings are only suitable for a specific range of rather large components with simple geometry such as outer diameters as pictured in Figure 5 and Figure 8. Equally, partial coatings, as necessary for MRO applications at MTU, are only feasible for simple rotationally symmetric geometries at areas that are easy to access.

Coefficient of friction: The tribological behaviour of thermal spray coatings depends on the coating material and their counterparts.

Layer thickness: The coating process of thermal spray coatings are mostly conducted by a robot or other articulating arm. The coating can be sprayed up to 500 µm thick directly to the designated location. This is why HVOF and plasma spraying are basically suitable for repair and overhaul work on worn components (Legg, 2012), except in cases were higher abrasion is to be compensated. Therefore, thermal spray coating cannot be considered as a reliable alternative to functional chrome plating in all cases, especially as the loss of material through wear is not equal for the individual parts. Coating procedure: Functional chrome plating processes are mostly automated and are well known since they have been applied for decades. For functional chrome plating the part is cleaned and masked, then left in the plating bath for a specific time varying largely for different applications from 20 minutes up to a day. Thermal spray coatings are based on completely different technologies. For thermal spray coating workers with adequate new skills are required who follow the process with constant attention and careful control in order to achieve a coating of the desired quality. In addition, the process is performed in booths due to the noise and dust formation and requires complex and cost intensive peripheral equipment as well as additional space requirements on the premises.

Corrosion resistance: The thermal spray coatings show different corrosion resistance depending on the method, the substrate and the coating material used.

In terms of HVOF, experiments revealed, that most of the coatings do not fulfil the minimum corrosion resistance requirements although there are exceptions. For example, CoCrMo, WCCoCr and Mo layers were tested for corrosion resistance. The CoCrMo-layer achieved 750 h in NSST which just fulfils the minimum requirements of 750 h. With CoCrMo-coatings good corrosion resistance is given to the substrate with an undercoat. Coatings such as WCCoCr and Mo against alloyed steel (35NCD16) performed worse in NSST and only reached 117 h which is insufficient compared to



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860 h for metallic chrome coatings. Mo coatings are in general considered as unsuitable for corrodible substrates.

Corrosion resistance of plasma sprayed Mo coatings to steel and stainless steel were tested to be poor with < 72 h salt spray test. Similar poor results were revealed for CoCrMo on steel, but latter could be increased to 750 h when applied on a NiCr underlayer.

Surface finish: Some HVOF coatings (e.g. WC-Co) result in rough surfaces that may require post treatment, depending on the application. This process step can be very expensive, because finish treatment of e.g. WC-Co requires costly diamond tools, whereas metallic chrome coatings can be treated with less expensive carbide tools.

Adhesion: Adhesion properties are not in line with the requirements from MTU. These coatings contain a high amount of ceramics (50 – 70 V% carbides). As these materials are of limited adhesion to metallic matrices, breakages can occur.

Surface Heating: Thermal spray processes include thermal and kinetic energy. These energies are focussed and the articles can reach temperatures > 2,500°C. Consequently substrate is heated up especially at the superficial layers. There are serious risks of overheating, crack building, and early fatigue because the substrate properties degrade when influenced by the heat. Thermal processes are limited to substrate materials that can withstand high process temperatures. However, thermal spray processes are not a like-for-like replacement for functional chrome plating for aircraft engine components and MRO purposes as applied at MTU.

Assessment overview for thermal spray coatings

Wear resistance Hardness Adhesion Complex Geometries Layer thickness

depends on the coating, loads, wear mechanisms and counterparts

depends on the technology and coating material

Coating procedure Surface heating Coefficient of friction Corrosion resistance Surface finish

Not for heat sensitive substrates

depends on the coating material/ tribological partner

depends on the coating material/ tribological partner

6.1.3. Economic feasibility The costs for thermal spray coating depends on numerous different factors and these are presented in a qualitative to semi-quantitative way below.

The technology for high velocity processes and functional chrome plating differ fundamentally in the equipment and peripherals. The implementation of thermal spray coating facilities in sufficient number and size requires complex machines and infrastructure equipment. The installation costs for completely new plant and machine lines comprise € 75,000-200,000 for equipment, € 75,000 for the robot and € 200,000 for the room, that is in total € 350,000 to 475,000 (Legg, 2003a). As MTU already established and uses these technologies, this is not considered as a hurdle.

A cost comparison cannot be done easily, as the concrete production costs depend on the size and geometry of the parts and can be up to 5-times higher than for functional chrome plating.

Aerospace industry expects that the production costs for HVOF are significantly higher which is due to higher equipment costs increased by set-up costs for each part, and higher costs for post-treatment (grinding and polishing). Divergence of costs are expected to be even higher for complex parts.



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6.1.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances (see Appendix 2.1.4) and products reported during the consultation were reviewed for comparison of the hazard profile.

As mentioned above, various different powder materials are used for high velocity processes, for which some substances are confidential business information. As an example, the hazard profile from an often-used coating material is illustrated. According to suppliers’ SDS, the following hazard statements are given for WC-12Co: Skin Irrit. 2, Eye Irrit. 2, STOT SE 3, Carc. 2. As such, transition from chromium trioxide – which is a non-threshold carcinogen – to WC-12Co would constitute a shift to significantly less hazardous substances. However, some cobalt compounds are on the REACH candidate list for substances of very high concern so an assessment on the hazardous profile of these substances would have to be performed on a case by case basis.

6.1.5. Availability In general, HVOF, plasma spraying, flame spraying, cold gas spraying and arc spraying are technologies implemented in house at MTU that are used for specific purposes (heat-insulating coatings, flanges, abradables) where not all key requirements have to be fulfilled. Especially for new aircraft engine development programs MTU is constantly reviewing if further replacements can be achieved. As per all the functional chrome plating replacements, there is less availability of aerospace qualified WCCo/WCCoCr HVOF than for functional chrome plating.

However, thermal spray coatings are currently not considered a like-for-like alternative to functional chrome plating. In the theoretical case that all technical limitations can be overcome, development and implementation as general metallic chrome coating alternative, will easily take more than 15 years.

6.1.6. Conclusion on suitability and availability for alternative thermal spray coatings Thermal spray coatings have been assessed based on MTU’s expertise as an experienced user of thermal spray processes for special applications. Thermal spraying might be used for specific simple geometries. If the drawbacks are overcome it could reduce the number of parts subjected to functional chrome plating for future aircraft engines components. More importantly, thermal spray coatings do not perform technically equivalent to metallic chrome coatings as complex geometries such as small IDs and partial coatings are not feasible. As these are considered key applications for MTU’s business, thermal spray coatings cannot be regarded as a general alternative to functional chrome plating.

The economic assessment of this alternative showed that production costs of HVOF can be up to 5 times higher compared to functional chrome plating. Additionally, some cobalt compounds used for thermal spray coatings are on the REACH candidate list for substances of very high concern. In conclusion, these systems are currently technically not equivalent to chromium trioxide-based functional chrome plating, have strong economic disadvantages and are therefore not a general alternative.

6.2. ALTERNATIVE 2: Nickel and nickel alloy electroplating

6.2.1. Substance ID and properties Nickel and nickel alloy electroplating is generally based on a similar technology as functional chrome plating, but with important differences in the anode design (Figure 19). Further differences are in the bath chemistry and some operating parameters such as voltage. Bath compositions are designed to



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either deposit a nickel coating or a nickel alloy coating. The Watts composition is a typical bath for the former coating containing nickel sulphate, nickel chloride and boric acid. Besides the Watts-type composition, nickel sulphamate is also a frequently used salt in sulphamate nickel plating. Suitable electrolytes for nickel alloy coatings in use at MTU comprise Nickel and Co electrolytes. Furthermore, nickel-cobalt (Ni-Co) or nickel-phosphorus (Ni-P) electrolytes are potentially suitable.

A Watts bath operates at a temperature between 25-60°C and a pH of 3.5-5.0 with a mean deposition rate of 40-90 µm/h. Raising pH to 5.5 increases deposit hardness, strength and internal tensile stress while ductility decreases. For Ni-P electroplating, NaH2PO4 is added to the Watts bath. Nickel sulphamate baths operate at similar process conditions. Magnetic and several textural properties as well as microstructure of Ni-P deposits are strongly dependent on the phosphorus content (Hu, 2000). Electrodeposited composite Ni-P coatings contain additives such as SiC significantly increase wear and corrosion resistance.

Figure 19: Nickel and nickel alloy electroplating process design (NDCEE, 1995).

The nickel-plating solution becomes contaminated by metals from different sources; most commonly dragged-in from previous treatments, corrosion products or work, tools, nuts, bolts, etc. which are dropped into the tank. Metallic impurities must be removed either continuously or at intervals by low current density electrolysis on a corrugated cathode.

A non-exhaustive overview of general information on properties of relevant substances used within this alternative, as well as the overall risk to human health and the environment is provided within Appendix 2.1.2.

6.2.2. Technical feasibility General assessment: The major advantage of nickel and nickel alloy electroplating is that it might be a close “drop-in” replacement for current chromium trioxide process technology. There is a basic fit of the necessary equipment for bath plating and depots but the anode design, bath chemistry and operation will need to be changed. Currently, nickel electroplating is often used in addition to chromium trioxide-based functional chrome plating as an undercoat to provide sufficient corrosion protection. However, the performance is not comparable to chromium trioxide-based coatings and suffers from technical limitations as described below.

Hardness: Nickel electroplates are rather soft with < 400 HV. Even significantly lower values are reported with 130-200 HV for Watts nickel and 170-230 HV for nickel sulphamate (Di Bari, 2010). Hardness can be improved by additional heat treatment. Most nickel alloy coatings seem to require



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post-heat treatment to reach acceptable hardness levels. Up to 1,000 HV can be reached for electrodeposited Ni-P after heat treatment at laboratory scale (Daly and Barry, 2003).

Electroplated nickel layers without temperature post-treatment do not reach the required hardness criteria in the aerospace sector applied at MTU of 800 – 1,100 HV with 450 HV (without hardening) to 750 HV (with hardening but which will decrease the corrosion resistance). With the extensive use of heat sensitive substrate materials for aeronautic applications with required hydrogen evolution temperatures < 150-250°C and stress relief with temperatures > 350°C, heat treatment is not an option to enhance hardness performance.

Wear resistance: The aerospace industry reported that wear resistance was significantly lower compared to metallic chrome coatings. The wear resistance of nickel electroplates can be increased by using nickel alloy or composite electroplates. Further R&D efforts are required to obtain more data for as-deposited and heat treated states.

There is a correlation between hardness and wear resistance: in general, as hardness increases, wear resistance decreases. To date, the wear resistance properties of nickel and nickel alloy electroplatings are not sufficient to replace functional chrome plating.

Coefficient of friction: The minimum requirement of the coefficient of friction for lubricated metallic chrome coatings is < 0.2. During the consultation it was stated that electroplated Ni layers are not able to fulfil this criterion as the coefficient values are higher. Key figures for coefficient of friction and wear resistance are not yet consolidated as electrodeposited Ni is typically used for corrosion protection only or as an undercoat.

Internal stress: Stress in electrodeposited nickel is of tensile or compressive nature depending on the chemistry and varies largely. Nickel sulphamate stress values range between 0-55 MPa and are lower than those of additive-free Watts Nickel sulphate with 125-185 MPa (compare to a maximum of 550 MPa for very thin metallic chrome coated plates without cracks). Thin plates can contain higher stress. High deposit stress can be of concern in electroforming where the adhesion between the electrodeposit and the mandrel is deliberately kept as low as possible in order to facilitate separation.

Adhesive coating properties: Metallic chrome coatings do have the property to be anti-adhesive. Water, grease, oil, dirt, and dust can be easily wiped off. Nickel coatings in general do not have this anti-adhesive behaviour and contaminants firmly stick to the surface. Corrosion resistance: A layer of nickel applied as undercoat (e.g. before functional chrome plating) raises the corrosion resistance of the coating system. However, nickel as a final layer can cause severe galvanic corrosion of the substrate (if coating is damaged). This is not the case with metallic chrome coatings probably due to formation of passive oxides on the surface. The nickel layer thickness also influences the corrosion resistance performance. An increase in corrosive service conditions requires an increase in the layer thickness (Watson, 1990).

Ability to plate complex parts: Electrolytically deposited Ni-P shows deficiencies to coat complex geometries with a highly uniform surface.

Microstructure: A nickel layer is compact and does not contain micro-cracks analogous to a metallic chrome coating. This impairs post-treatment working steps on nickel and nickel alloy coatings such as sealing or lacquering.

Assessment overview for nickel and nickel alloy electroplating

Hardness Wear resistance Coefficient of friction

Ability to plate complex parts

Adhesive properties Microstructure



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6.2.3. Economic feasibility Against the background of significant technical failure of nickel electroplating, no quantitative analysis of economic feasibility was conducted. However, the cost for nickel electroplating depends on numerous different factors and these are presented in a qualitative to semi-quantitative way below.

It was stated that the electricity costs during the plating process are four times lower compared to functional chrome plating. In contrast, the reactants for nickel electroplating are more expensive than the chromium reactants.

Including further related costs such as investment costs for process restructuring, different anode technology, installation of new baths, etc., maintenance and chemical costs, the electrodeposition of nickel coatings, for instance Ni-P, was evaluated to be 2-8 times more expensive than functional chrome plating.

6.2.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances and products reported during the consultation were reviewed for comparison of the hazard profile. Based on the available information on the substances used within this alternative (refer to Appendix 2.1.1) nickel sulphate constitutes the toxicological worst case scenario and is classified as Skin Irrit. 2, Skin Sens. 1, Resp. Sens. 1, Muta. 2, Carc. 1A, Repr. 1B, STOT RE 1, Aquatic Acute 1, Aquatic Chronic 1. As such, transition from chromium trioxide – which is a non-threshold carcinogen – to the above mentioned alternative would clearly not constitute a shift to less hazardous substances. Based on the classification, soluble nickel compounds may meet the SVHC criteria under REACH. As some of the alternate substances used are also under observation, the replacement has to be carefully evaluated on a case by case basis.

Amongst the composites used within this alternative, boric acid constitutes the toxicological worst case scenario and is classified as Repr. 1B. Boric acid is included into the 6th draft recommendation of priority substances. Therefore, the use of boric acid may become time limited by potentially transferring boric acid to the REACH authorisation (Annex XIV). Additionally, some cobalt compounds are on the REACH candidate list for substances of very high concern so an assessment on the hazardous profile of these substances would have to be performed on a case by case basis.

In summary, electroplates based on nickel do not constitute a shift to significantly less hazardous substances.

6.2.5. Availability Nickel electroplating is a commercially available process, similar to functional chrome plating but with different anode technology, bath composition and ingredients. Nickel electroplating is usually used as an undercoat for functional chrome plating and repair with metallic chrome coatings

Currently, there are ongoing efforts of the electroplating industry, metal parts manufacturers, and suppliers to improve the wear and corrosion resistance of the Ni-P alloy coating and make it a potential metallic chrome coating replacement. However, the testing is time intensive and several years are scheduled for further research.

MTU does not consider nickel electroplating as functional chrome plating replacement. Plating of aircraft engine parts with chromium trioxide is often a combination of nickel strike, functional chrome plating, mechanical post-treatment and/or paint.

In general, nickel electroplating is not considered a like-for-like alternative to functional chrome plating and more than 15 years would be needed to develop a general metallic chrome coating alternative.



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6.2.6. Conclusion on suitability and availability for alternative nickel and nickel alloy electroplating

Nickel coatings are widely used as one component in multi-layer systems with a final metallic chrome coating. In these systems, the combination of different layers provides satisfactory performance regarding the key functionalities (hardness, friction, wear, corrosion, adhesion). Systems consisting of a single nickel electroplated coating do not show satisfactory results during testing regarding the previously mentioned key functionalities. As nickel electroplating is usually used as an undercoat for functional chrome plating and repair with metallic chrome coatings, the alternative cannot substitute functional chrome plating for MRO purposes. Although nickel electroplating is a commercially available process, it is not suitable as general alternative for functional chrome plating. Nickel alloy electroplating as an alternative to functional chrome plating is at early laboratory scale. Significant time, financial and R&D efforts are necessary to evaluate the potential future replacement of chromium trioxide. Furthermore, the chemicals used for this alternative do not constitute a significant shift towards less hazardous substances according to their classification (Ni-compounds) or are a SVHC and already proposed for inclusion on REACH Annex XIV (boric acid).

6.3. ALTERNATIVE 3: Chemical vapour deposition (CVD)

6.3.1. Substance ID and properties CVD as well as plasma enhanced chemical vapour deposition (PECVD) are assessed together as alternative as they basically refer to the same process but with different process conditions (TURI, 2006):

- Thermal / low pressure CVD (sub-atmospheric pressure and high temperature) and - Plasma enhanced CVD (lower temperature with heat generated by electrical plasma).

In general it can be distinguished between thick and thin CVD. In the thin CVD-process reactant gases (normally mixed with inert gases) enter a reaction chamber at room temperature and are then heated or passed over a heated substrate. The processing temperature is normally 1,000°C. A typical CVD system is shown in Figure 20.

Figure 20: Typical CVD system (Legg, 2003a).



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Materials, called precursors, are brought into the deposition area in the gas phase, exemplarily illustrated as precursor 1 and 2. Gases contain the desired coating materials such as metal halides, metal carbonyls, hydrides or organometallic compounds in vapour phase. Possible coating materials are e.g. titanium carbide, titanium nitride, titanium carbon nitride, silicon carbide, titanium boride, aluminium oxide.

After being absorbed onto the surface of the substrate, the reactants are decomposed and react with the substrate to form the coating. By-products are then removed from the chamber. Conducting the CVD process under sub-atmospheric pressure tends to reduce unwanted gas-phase reactions and improve film uniformity across the substrate. Thick CVD coating is applied by a chemical vapour deposition process similar to the thin CVD process. It involves a gas phase reaction in which one of the reactant gases is a source of tungsten and one a hydrocarbon (the carbon course). Depending on the exact set conditions, the processing temperature can be kept below 500°C meaning that it is more applicable to a wider range of materials such as steel, stainless steel, nickel, copper, cobalt and titanium alloys.

The coating is a binder-free, homogeneous & pore-free tungsten / tungsten carbide graduated coating applied for its sliding wear properties and barrier corrosion resistance. Different properties such as in hardness and toughness may be obtained by changing the processing conditions.

PECVD: The reaction can also be initiated by plasma (ionised gas) instead of heat. The advantage of plasma enhanced CVD is that it is possible to only heat the surface region where the reaction occurs while the core of the component is maintained at a comparatively lower temperature. Due to lower processing temperature, PECVD is applicable to a broader range of materials, especially heat sensitive material.

A non-exhaustive overview of general substances information used for (thin) chemical vapour deposition and the risk to human health and the environment caused by these substances, is provided within Appendix 2.1.3.

6.3.2. Technical feasibility General assessment: For the application at MTU only thick CVD is relevant, as thin CVD is not suitable for repair and overhaul of aircraft engines due to limited layer thickness. Consequently it is impossible to rebuild the dimensions of worn or damaged components according to the original specifications (Legg, 2012), because repair coatings require deposition of greater quantities of material.

CVD can be used for turbine blades and hot section engine components, but is totally unsuitable for structural components (Legg, 2003a). The process is used at MTU for typically small and/or high value items with high production volumes of aircraft engine parts that are subject to high temperatures (>600°C). These parts are typically not chrome coated e.g. alitised (CVD based process using Al2O3 powder) turbine blades and guide vanes. The generated diffusion coatings serve as protective layers against high temperature corrosion and high temperature oxidation in aircraft engines. Partial coatings: For MRO purposes, usually partial coatings are required in order to restore the original shape of a component. To achieve partial coatings with functional chrome plating, those areas that are intended to remain uncoated are covered with thick wax layer where no coating material can deposit. After the process the wax can easily be removed again (for an illustration the reader is referred to Figure 6 to Figure 8 above). Due to the high temperatures within the process this technique is not practicable for CVD, as the wax just melts. Other covers proved to be either not practicable or not economical. For example when using another heat resistant metal as a cover, high amounts of coating material (90-95%) are lost as they are deposited on the cover and recycling is a disproportionately big effort. As described in Chapter 2.3.2.1, it is of utmost importance that those



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areas of the part exposed to high vibrational load remain uncoated to prevent cracking or fracture of the component while in service. Therefore, the CVD process is not suitable to replace functional chrome plating in the use applied at MTU as there is no possibility of applying the coating material to defined areas only.

Hardness: Depending on the type of coating typical hardness of thick CVD coatings can range from 800-1,600 HV which is sufficient for aircraft engine components. The deposition rate is significantly lower than in the functional chrome plating process at lower temperatures and similar at high temperatures such as 1,000°C only (compare 20-40 µm/h for functional chrome plating versus 1-5 µm/h for CVD). Wear resistance: The thick CVD coating has shown itself to be equal or superior to metallic chrome coatings in sliding wear by bench testing in configurations such as against bronze bearing materials but not against harder substrates. Testing has shown it to offer good barrier corrosion protection and for it to be able to coat complex geometries. It has limited use in military aircraft and is currently being qualified by a major commercial aircraft manufacturer.

Process Temperature: The CVD process usually requires the surface to be red hot for thermally driven CVD (around 1,000°C), which limits the types of substrates and alloys that can be coated. The high temperatures may lead to a distortion of component and changes in properties of the substrate. Therefore CVD is rarely used in combination with heat-sensitive materials. Using plasma or more expensive metalorganic gases reduces the process temperature to about 500°C which still exceeds the processing temperature of many alloys (e.g. high strength steel, aluminium) (Legg, 2012). As long as their processing temperatures are above the temperature needed for the chemical vapour deposition, a variety of coating materials can be used.

Layer thickness: The coatings provided by the thick CVD process are usually about 50 μm thick and the maximal achievable layer thicknesses can be in excess of 100 μm (refer to http://www.hardide.com/). For MRO purposes, the main application of functional chrome plating at MTU, this is not sufficient as it depends on the grade of abrasion how much material is needed to restore the original shape of the component. This can be as little as 100 µm up to more than 500 µm.

Size of parts: Another significant disadvantage of this alternative is the need of a vacuum chamber. As the size for vacuum chambers is limited for physical reasons, batch size decreases considerably with increasing size of the plated parts. Currently, typical reaction chambers can accommodate maximum dimensions of up to 1.2 m. From a technical point of view, CVD is not suitable for large but rather for small parts such as turbine blades and guide vanes, especially in combination with sub-atmospheric pressure.

Complex geometries: Thick CVD is adaptable to a wide variety of parts, shapes, and sizes. It is not confined to line of sight and thus is particularly suitable for application to complex geometries (including bores and cavities) requiring wear protection up to “high load” situations.

Thick CVD coating cannot be considered as a general replacement to metallic chrome coatings because of e.g. high temperature of the process, the limitation for partial coatings and the insufficient layer thickness. It offers promising tribological properties suitable for materials that are not affected by the high process temperature such as many stainless steels.

Assessment overview for CVD

Partial coatings Hardness Wear

resistance Process temperature

Corrosion resistance

Complex geometries

Layer thickness Size of parts

Depending on tribological partner

For most substrates

Size limitation of parts

http://www.hardide.com/



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6.3.3. Economic feasibility Against the background of significant technical failure of thick CVD, no quantitative analysis of economic feasibility was conducted. However, the cost for thick CVD depends on numerous different factors and these are presented in a qualitative to semi-quantitative way below.

CVD processes include relatively high costs because it is a complex technology that requires a vacuum chamber. The costs for the equipment are indicated to be $1-2 million for the coating system, with additional costs for pre- and post-treatment (Legg, 2012). Especially for small components that require a long life-time, CVD can be a cost-effective alternative to functional chrome plating.

Aerospace companies confirm that costs (including energy consumption) are higher, compared to functional chrome plating, especially if the processed volumes are low. The deposition rate is significantly lower than in the functional chromium trioxide plating process, compare 20 - 40 µm/h for functional chrome plating versus a maximum of 1 - 5 µm/h for CVD. Additionally, long times are needed for vacuum generation.

However, a general economic assessment is not possible because the process costs depend on nature of component (batch process), energy consumption and chamber size. Costs for thick coatings may be competitive for parts with complicated geometry for which thermal spray coatings would be unsuitable.

6.3.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances and products reported during the consultation were reviewed for comparison of the hazard profile. Based on the available information on the substances used within this alternative (see Appendix 2.1.2), aluminium oxide, as toxicological worst case, is classified as Stot SE 3, Acute Tox. 4. As such, transition from chromium trioxide – which is a non-threshold carcinogen – to one of these substances would constitute a shift to less hazardous substances.

CVD can involve the use of hazardous materials such as carbon monoxide gas, hydrogen gas, hydrochloric acid and liquid chlorides (e.g. titanium chloride, vanadium chloride). It also generates waste gases that must be collected and the chamber also needs periodic cleaning; fluorinated gases (greenhouse gases) may also be used (TURI, 2006).

6.3.5. Availability CVD is an established process at MTU, where CVD coatings are mainly used as protective diffusion layers against high temperature corrosion and -oxidation. Clearly, these coatings are used in different application fields as they have a completely different microstructure than metallic chrome coatings. Due to the technical limitations above it cannot be used for restoring the original shape of parts as it is done with functional chrome plating. It is not known if this process will ever qualify as general alternative for aircraft engine components and MRO applications.

6.3.6. Conclusion on suitability and availability for alternative CVD The thick CVD process is established at MTU for specific applications where high temperature corrosion and -oxidation protection is the main purpose. CVD cannot be used for restoring the original shape of components nor for producing partial coatings as it is done with functional chrome plating. In combination with additional technical limitations thick CVD processes do not represent a suitable alternative to replace functional chrome plating for aircraft engine components and MRO applications at MTU.



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6.4. ALTERNATIVE 4: Nanocrystalline cobalt phosphorus alloy coating

6.4.1. Substance ID and properties Nanocrystalline cobalt-phosphorus alloy (nCo-P) coatings are electrodeposited in an aqueous bath process that uses pulse plating technology. Pulse technology enables controlled deposition of nano grains (5-15 nm) resulting in an ultra-fine grain structure throughout the entire coating thickness from the substrate surface (Facchini et al. 2009; Legg, 2003b, Figure 21). The steel industry also investigates Ni-W (nickel-tungsten) alloys with this electrodeposition method.

Figure 21: Microstructure of nano CoP coatings (Legg, 2003b).

As the process is similar to the electrodeposition of functional chrome plating and compatible with current functional chrome plating infrastructure, it is considered to be a possible drop-in replacement. According to information from aerospace companies, the Co plating process is not yet a mature technology. Significant process performance parameters are summarised in Table 8.

Table 8: Comparison in process performance for nCoP and functional chrome plating (McCrea et al., 2003 and Gonzales, 2010).

nCoP alloy Functional chrome plating

Deposition method electrodeposition electrodeposition

Applicable geometries

line-of-sight non line-of-sight

line-of-sight non line-of-sight

Bath chemistry CoCl2 / H3PO4 CrO3 / SO42-

Efficiency 85–95% 15–35%

Deposition rate 50–200 µm/h 20–40 µm/h

A non-exhaustive overview of general information of substances used within this alternative, and the risk to human health and the environment caused by this substances, is provided in Appendix 2.1.4.

6.4.2. Technical feasibility The following table provides an overview of the performance of nCo-P coatings. In addition, cobalt is sensitive to alkaline cleaners.



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Table 9: Material properties of nano Co-P alloys (McCrea et al., 2003 and Gonzales, 2010).

Property nCoP alloy

hardness (as deposited) 600–700 HV

hardness (heat treated at 250°C) 700–800 HV

hardness (heat treated at 400°C) 1,000-1,200 HV

wear resistance (Taber test) 27 mg/1,000 cycles

Hardness: As illustrated in Table 9, the hardness of as-deposited nCo-P alloys is in the range of 600-700 HV (Vickers Testing ISO 6507-1) and therefore inferior compared to metallic chrome coatings with 700-1,400 HV. Annealing (heat treatment) after electrodeposition at 300-400°C leads to an increased hardness between 700-800 HV and 1,000-1,200 HV. However, heat treatment can easily result in changes of the substrate microstructure and lead to degradation of coating and substrate properties. Heat treatment can only be used for materials which are not heat sensitive (Facchini et al., 2009; Holeczek, 2011). Heat sensitive substrate materials (e.g. aluminium alloys, high strength steel) are widely used in the aerospace sector. The deposition temperature for aluminium alloys has to be < 150°C and for high strength steels < 250°C. Heat treatment of these substrates at temperatures > 300–400°C for several hours is not suitable to achieve better hardness performance.

In summary, the hardness requirement cannot be fulfilled by as-deposited coatings and annealing is not an option for increased hardness due to material degradation.

Partial coatings: According to McCrea et al. (2003), the bath temperature ranges from 70-85°C, which is not practicable, as the wax normally used melts. Other covers proved to be either not practicable or not economical. Wear resistance: Low achievable hardness can be an indicator for low wear resistance in service environments where the coating is extremely stressed. Abrasive (Taber) wear testing of nCo-P alloys confirms that these alloys are less resistant to wear than metallic chrome coatings. The abrasion of nCo-P alloys is 27 mg/1,000 cycles and the abrasion of metallic chrome coatings is about 2-3 mg/1,000 cycles. The wear resistance, as one key requirement, is a limiting factor because nCo-P coatings are about 10-times less wear resistant than metallic chrome coatings.

Layer thickness / Rebuilding of parts: It was demonstrated that a coating thickness of 500 µm can be achieved with nCo-P layers (McCrea et al., 2003). No information is available if tribological properties or microstructure are subject to change with increasing layer thickness, as it is the case for metallic chrome coatings. Considering the possible thickness of nCo-P layers, rebuilding of parts may be feasible.

Complex geometries: It was demonstrated that complex geometries such as small and large IDs can be coated with nCo-P layers (McCrea et al., 2003).

Microstructure: The deposited nCo-P layer is compact, rough and does not contain micro-cracks analogous to a metallic chrome coating. This impairs post-treatment working steps on nickel and nickel alloy coatings such as sealing or lacquering.

Corrosion resistance: nCo-P alloys show superior corrosion resistance to metallic chrome coatings, with 50% thinner layer. Tests were conducted (according to ASTM B117) with layer thicknesses of 50 µm for nCo-P and 100 µm for metallic chrome coatings. The nCo-P alloy performed very well and showed an approximately stable corrosion resistance during 1,000 hours of testing time, compared to metallic chrome coating with continuously decreased corrosion resistance after the same exposure time (Facchini et al., 2009).



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With regard to clearly insufficient technical performance, nCo-P coatings are currently not an equivalent replacement for chromium trioxide for applications at MTU.

Assessment overview for nCo-P-coating

Hardness Partial coatings

Wear resistance

Layer thickness /

Rebuilding of parts

Complex geometries Microstructure Corrosion

resistance

6.4.3. Economic feasibility Against the background of significant technical failure of nCo-P coating, no quantitative analysis of economic feasibility was conducted.

However, in one publication it was stated that compared to functional chrome plating, the energy consumption can be reduced while throughput is increased (due to high deposition rate up to 0.2 mm/h for nCo-P and up to 0.04 mm/h for functional chrome plating). This results in higher plating efficiency (about 90% for nCo-P compared to less than 35% for functional chrome plating). The relative process costs of nCo-P plating with 1.3 are reported to be slightly higher compared to 1.0 with functional chrome plating (McCrea et al., 2003).

6.4.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances and products reported during the consultation were reviewed for comparison of the hazard profile. Based on the available information on the substances used within this alternative (see Appendix 2.1.3), cobalt dichloride, as worst case scenario, is classified as Acute Tox. 4, Skin Sens. 1, Resp. Sens. 1, Muta. 2, Carc. 1B, Repr. 1B, Aquatic Acute 1, Aquatic Chronic 1. While this substance is currently not included in the candidate list, other cobalt compounds are on the REACH candidate list for SVHC. As such, transition from chromium trioxide – which is a non-threshold carcinogen – to one of these substances would not constitute a shift to significantly less hazardous substances.

6.4.5. Availability Electrodeposition of nCo-P layers is in early laboratory stages at low TRL. The equipment and bath chemicals are commercially available. However, it is no drop-in replacement for existing functional chrome plating equipment, and not a mature technology. Based on the technical deficiencies it is questionable whether nCo-P coatings will be part of future investigation in the described sectors. As MTU does not have any experience with this technology, at least 15 years would be needed to develop nCo-P as a general metallic chrome coating alternative, if ever.

6.4.6. Conclusion on suitability and availability for alternative nanocrystalline cobalt phosphorus alloy coating

nCo-P coatings cannot fulfil the required specifications of MTU with regard to hardness, wear resistance and the ability to partially coat surfaces. The process may be used for restoring the original shape of aircraft engine components for MRO applications.

In summary, nCo-P coatings are technically not feasible nor is the implementation of a Co-containing replacement technology desirable from a health perspective. Therefore, this process does not represent a suitable alternative to replace functional chrome plating for aircraft engine components and MRO applications at MTU.



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CATEGORY 2 ALTERNATIVES

6.5. ALTERNATIVE 5: Electroless plating

6.5.1. Substance ID and physicochemical properties of relevant substances Electroless plating is a process in which metal ions in a dilute aqueous solution are deposited on a substrate by means of a heat induced reduction (see Figure 22) without the use of electric current. Heat induced reduction is a chemical reaction in which the substrate acts as a catalyst after being heated, causing ions to continuously deposit onto the substrate. Chemicals, such as hypophosphite, reduce metallic ions in the electroless plating solution to form a coating. Once a metal is reduced and deposited, the metal surface acts as a catalyst for further deposition in that location (NDCEE, 1995).

Figure 22: Electroless nickel plating (NDCEE, 1995).

Nickel represents the most widely used base material for electroless plating. Electroless nickel deposits usually consist of nickel-phosphor (Ni-P) or nickel-boron (Ni-B) alloys. Typical bath solutions contain reducing agents, such as hypophosphite, aminoborane or borohydride and are used to deposit Ni-P or rather Ni-B alloys. The primary goal behind the alloys is to enhance existing nickel layer properties.

The chemical reaction sequence is shown below for a hypophosphite bath which is commonly used to deposit Ni-P:

Another possibility to ameliorate the layer properties is to incorporate additive particles (such as silicon carbide, diamond, PTFE (Polytetrafluoroethylene), tungsten carbide) into the Ni layer to form composite coatings. The bath temperature of phosphorus based chemistry is about 90°C whereas a boron based bath operates at lower temperatures.

A non-exhaustive overview of general information and properties of substances used in electroless plating as well as the overall risk to human health and environment caused by these substances, is provided within Appendix 2.1.5.



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6.5.2. Technical feasibility As nickel phosphorous (Ni-P) deposits are the most promising alternatives amongst the electroless nickel coatings, these were used for the assessment. The figures in the following table which was provided in the consultation with the CTAC consortium illustrates the effect of different phosphorous contents on the technical properties of the Ni-P alloy layers.

Table 10: Typical properties of electroless nickel-phosphorus coatings.

Low P-content (1–4 %)

Medium P-content (6–9 %)

High P-content (> 11–12 %)

Structure crystalline crystalline and amorphous amorphous

Hardness (as deposited) 700 HV 600 HV 530 HV

Hardness (heat treated) 960 HV 1,000 HV 1,050 HV

Wear resistance (as-deposited) (Taber wear index)

11 mg/1,000 cycles 16 mg/1,000 cycles 19 mg/1,000 cycles

Wear resistance (heat treated) (Taber wear index)

9 mg/1,000 cycles 12 mg/1,000 cycles 12 mg/1,000 cycles

Coefficient of friction not determined 0.38 0.45

Corrosion resistance (salt fog test) 24 h 96 h 1,000 h

Hardness, wear resistance and corrosion resistance are the most important key performance parameters, and respective minimum requirements have to be fulfilled in order to be an appropriate alternative for chromium trioxide-based electroplating.

Hardness: The hardness depends on both the phosphorous content and the heat treatment after the deposition process. In an as-deposited state low P-content alloys show values of 700 HV that decrease with higher phosphorous content (down to 530 HV for a high P-content alloy). The minimum requirements for metallic chrome coating of MTU for hardness is 800 HV and not achieved by this alternative.

A possibility to improve hardness performance compared to the as-deposited state is heat treatment. However, heat treatment damages the ability of the coating to act as a barrier for corrodible materials. The deposition temperature for aluminium alloys has to be below 150°C and for high strength steels below 250°C. Above 220°C corrosion resistance is reduced because of the introduction of grain boundaries and micro-cracking in the nickel matrix. Heat treatment conducted at 400°C of about one hour creates precipitates that give the coating its maximal hardness up to 1,050 HV. This hardness is similar to functional chrome plating, but the corrosion resistance is simultaneously reduced by a factor of 100 (Legg, 2003a). However, with increasing onset time of the component at high temperatures of about 400°C as in aircraft engines, hardness and wear resistance of chemical Ni-coatings declines again. This means the hardness of a component could decrease while in service in the engine.

Wear resistance: Alloys with low P-content (with and without heat treatment) show better wear resistance and have lower Taber wear index values compared to medium and high P-content alloys (see Table 10). However, the wear resistance of a low P-content + heat treated Ni-P alloy is worse compared to metallic chromium (as-deposited: 2 mg/1,000 cycles).

Layer thickness/constitution: Since the deposition of electroless nickel is based on autocatalytic reaction and not on electric field distribution through electrodes, uniform and variable layer thickness even on complex parts geometries and edges is possible. Electroless nickel plating produces thin



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layers of maximum 100 µm. This is not sufficient for rebuilding of aircraft engine parts, which is the primary use for functional chrome plating at MTU.

The particles’ suspension and deposition uniformity in composite coatings are difficult to control. This makes it difficult to achieve homogeneous coating properties within nickel composite coatings containing particles (such as diamond, PTFE, etc.). Layer degradation and poor performance of the layer are possible consequences of uneven particle distribution (Legg, 2012).

Coefficient of friction: The data concerning the coefficient of friction shows a tendency to increasing coefficients with increasing P-content, which means a degradation of the friction behaviour with increasing P-content. In composite coatings, the coefficient of friction can be increased by including additives in a similar way to metallic chrome coatings. Corrosion resistance: The ability of electroless nickel deposits to provide protection in corrosive environmental conditions is influenced by the post-treatment of the Ni layer, and in case of phosphor alloys by the phosphorous content. Nickel can cause severe galvanic corrosion of the substrate or the counterpart if the coating is damaged. This does not occur with metallic chrome coatings, probably due to the formation of passive oxides on the surface. The corrosion resistance for electroless deposited nickel coatings in an as-deposited state were tested and evaluated by the aerospace sector. The corrosion resistance for electroless deposited nickel coatings in an as-deposited state (without hardening) were tested and evaluated as sufficient although corrosion performance of the technologies can vary. The specified salt spray resistance of electroless deposited nickel coating in an as-deposited (high phosphorous) is 336 hours. The Ni alloy with high P-content is the only coating in Table 10 that could fulfil the metallic chrome coating requirement, but at the same time hardness requirements cannot be met by this coating (as-deposited: 530 HV).

6.5.3. Economic feasibility Against the background of significant technical failure of electroless nickel plating, no quantitative analysis of economic feasibility was conducted. However, the cost for electroless nickel plating depends on numerous different factors and these are presented in a qualitative to semi-quantitative way below.

Generally Ni is the most expensive coating used at MTU to date, as costs for chemicals are significantly higher compared to other coatings, even compared to silver coating. However, the grinding post-treatment (a prerequisite for functional chrome plating), is not required. Costs depend on many factors including part size, geometry, and post treatments. Post-heat-treatment (higher energy costs) must be taken into account if increased hardness is required for selected parts for which the significantly reduced corrosion resistance is still sufficient (Legg, 2003a). Slow deposition rates require longer process times making the process also more expensive.

Chromium trioxide baths require € 500 maintenance costs per year per m³ for recycling. The nickel bath maintenance costs are at least 7 times higher, since they are stable for hours only. The disposal of these baths is very expensive and elaborate. In addition, the costs for nickel reactants are higher than for functional chrome plating.

6.5.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances and products reported during the consultation were reviewed for comparison of the hazard profile. Based on the available information on the substances used within this alternative (refer to Appendix 2.1.5) nickel sulphate constitutes the toxicological worst case scenario and is classified as Skin Irrit. 2, Skin Sens. 1, Resp. Sens. 1, Muta. 2, Carc. 1A, Repr. 1B, STOT RE 1, Aquatic Acute 1, Aquatic Chronic 1. As such, transition from chromium trioxide – which is a non-threshold carcinogen



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– to the above mentioned alternative would clearly not constitute a shift to less hazardous substances. Based on the classification, soluble nickel compounds may meet the Substances of Very High Concern (SVHC) criteria under REACH.

In addition, the size of composites such as diamond, PTFE, etc. which might be added to the process, can range from nanometres up to several microns. Depending on their size-specific properties, nanoparticles may pose additional risks to human health, especially via inhalation, which need to be adequately evaluated and addressed for material handling and working exposure.

Aside from nickel, the bath chemistry can contain lead and cadmium as further hazardous substances. The legal limits related to RoHS (restriction of hazardous substances) in articles are Pb 0.1% (1,000 ppm) and Cd 0.01% (100 ppm).

Electroless nickel baths have a finite bath life-time and at MTU last approx. 3 metal turnovers, depending on how the bath chemistry is maintained and on the materials being processed. As nickel is plated onto the part, the nickel concentrations in the bath decrease over time. Nickel sulphate is periodically added to replenish these losses. At the same time sulphate accumulates. When 100% of the original nickel content has been replaced, this is defined as one metal turnover. After 3 metal turnovers, the bath content must be dumped and disposed of as hazardous waste. Baths must also be dumped if they get contaminated with certain metals, e.g. chromium: for a low-P bath, 3 ppm of Cr(III) creates unacceptable deposits, while 0.2 ppm of Cr(VI) stops deposition completely. Given that a high percentage of components being internally plated will have chromium plated surfaces, the risk of contamination is high (National Center for Energy and Environment, NDCEE, 1995). In contrast to this, the baths for functional chrome plating are far less susceptible and can be used over decades without a full reset as it is the case at MTU.

6.5.5. Availability The electroless deposition of nickel is a well-defined process which has been in commercial use since the 1950s for certain products. Ni-P coating solutions are commercially more available than Ni-B and electroless nickel composite coating solutions (Legg, 2003a). At MTU, electroless nickel is used for anti-fretting coatings on some titanium parts for aircraft engines. However, the alternative is not a like-for-like replacement for chromium trioxide functional chrome plating and failed to gain wide acceptance in the aerospace industry.

There is a number of suppliers selling commercial plating equipment and bath solutions. NDCEE states that if electroless nickel is to be used very widely, methods will need to be developed and made commercially available to continuously monitor and control the bath chemistry, temperature, and performance as well as to control the heat treatment temperature and time. The use of composites would make such control methods even more important, since one must control bath chemistry more closely to prevent deposition onto bath particulates and one must control the particulates themselves. Methods must be found to maintain the filler powders in a uniform concentration and to obtain proper entrainment in the coating. This is clearly a concern for more difficult geometries.

Electroless deposition of nickel is not considered a like-for-like alternative to functional chrome plating. More than 15 years would be needed to develop a general metallic chrome coating alternative, and it is questionable whether this alternative will be part of future investigation in the described sectors.



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6.5.6. Conclusion on suitability and availability for alternative electroless nickel plating To date, electroless deposited nickel is used in certain products but it cannot replace metallic chrome coatings with all their functionalities as a stand-alone alternative. Electroless nickel shows significant technical (and therefore unacceptable) deficiencies regarding wear resistance, anti-adhesion and layer thickness, the latter being the main reason why this technology cannot be used for MRO.

6.6. ALTERNATIVE 6: Case hardening: carburising, carbonitriding, cyaniding, nitriding, boronising

6.6.1. Substance ID and properties A description of case hardening as an alternative process, including the frequently used substances, follows in the next chapter.

Process description Case hardening is a very common process that is used to harden the outer surface of metals creating a hard outer metal layer (“case”) while the deeper metallic material is unaffected, see Figure 23. The common nature of all case hardening processes is heat treatment of a metal substrate. The atmosphere contains an excess of a gaseous (or liquid) phase of the used substance, the dopant. The dopant then diffusively enters the outer layer of the metal creating the case. The process is predominantly related to steel, low carbon steel and other iron alloys. In the case of carburising, carbon (carbon source such as carbon monoxide) is the dopant while carbo-nitriding is based on carbon and nitrogen. The dopant of cyaniding is cyanide, nitrogen for nitriding and boron for boronising. Although dopants are commonly used, case hardening can also be conducted without dopants for certain metal alloys by heating the metal substrate (e.g. by induction) and cooling it down quickly.

Figure 23: Case hardening (NDCEE, 1995).

The case hardened area affected by the respective dopant varies depending on time and temperature of the process. The longer the treatment and the higher the temperature, the deeper the dopant is introduced into the substrate. The typical temperature of case hardening processes is between 500 to 1,000 °C (TURI, 2006). The hardness of case hardened surfaces ranges between approx. 550 to 1,200 HV depending on the process, process temperature, dopants, and substrate used.

A non-exhaustive overview of general information of substances used within this alternative and the risk to human health and the environment caused by this substances, is provided in Appendix 2.1.6.

6.6.2. Technical feasibility Process temperature: Case hardening is used in order to increase hardness of a material surface. During case hardening, the parts are subjected to high temperatures, which can melt temperature sensitive alloys. As a consequence the process temperatures limit the substrates and applications. The deposition temperature for aluminium alloys has to be < 150°C and for high strength steels < 250°C.



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Thus, case hardening processes cannot be applied as they are conducted at temperatures above this value. The aluminium substrate would either be distorted or melted away.

Hardness: Case hardening processes result in a structural change of the substrate, leading to increased hardness of the upper 3-4 mm with "soft" metal underneath. The change of microstructure does not lead to an additional layer or improves resistance to wear or corrosion. A nitride layer for example can rather be used as "undercoat" to provide additional hardness to the surface but it needs a corrosion resistant layer on top. An additional metallic chrome coating on parts that are exposed to wear makes it possible to increase their life-time as they can be repaired.

Layer thickness/ Rebuilding of parts: For MRO purposes, an alternative to functional chrome plating must necessarily build up an actual layer, to allow compensation of material losses on the part derived from wear. Case hardened surfaces are in general not suitable for rebuilding, as substrate is converted and no additional coating is deposited, the upper "treated" layer is not regenerative. Therefore case hardening techniques are in general no alternative for functional chrome plating for MTU’s purposes.

In addition, the case hardened surfaces are characterised as less anti-adhesive, with poor friction and corrosion performance. Due to the required high temperatures, case hardening is energy intensive.

6.6.3. Economic feasibility Against the background of significant technical failure of case hardening, no quantitative analysis of economic feasibility was conducted. However, concerning the economic feasibility, the cost factor was reported to be three times higher for case hardening processes compared to functional chrome plating.

6.6.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances and products reported during the consultation were reviewed for comparison of the hazard profile. Based on the available information on the substances used within this alternative (see Appendix 2.1.6), sodium cyanide, is classified as Acute Tox. 2, Acute Tox. 1, Eye Dam. 1, Acute Tox. 2, Aquatic Acute 1, Aquatic Chronic 1. Furthermore, carbon monoxide is classified as Press. Gas, Flam. Gas 1, Acute Tox. 3, Repr. 1A, STOT RE 1.

As such, transition from chromium trioxide – which is a non-threshold carcinogen – to one of the above mentioned alternatives would constitute a shift to less hazardous substances. However, some of the used alternate substances are also under observation regarding their toxicity. Therefore, the replacement has to be carefully evaluated on a case by case basis.

6.6.5. Availability Case hardening is a well-defined process that is commercially available, and used in the aerospace industry for specific applications. However, as clearly described above, it cannot replace functional chrome plating for MTU’s purposes.

6.6.6. Conclusion on suitability and availability for alternative case hardening Case hardening can fulfil the requirements on hardness depending on the substrate and process, but a combination of requirements of hardness, corrosion resistance and the possibility to rebuild parts is generally needed which cannot be achieved by case hardening. In summary, case hardening processes are not a general alternative for functional chrome plating.



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6.7. ALTERNATIVE 7: Trivalent chrome plating

6.7.1. Substance ID and properties / Process description The trivalent chrome (Cr(III)) plating alternative relates to an electrodeposition process for producing a metallic chrome coating from a trivalent chromium electrolyte. The chromium in the electrolyte derives from chromium trichloride. The Cr(III) plating process is in general based on a similar electroplating technology as the process with chromium trioxide. However, there are important differences regarding the anodes used and additional pulse-reverse equipment, such as the rectifier, which is significantly more expensive than the equipment needed for functional chrome plating from chromium trioxide. Further differences are in the bath chemistry and some operating parameters such as pulse plating for Cr(III) instead of traditional direct current plating for chromium trioxide (TURI, 2012).

A non-exhaustive overview of general information of substances used within trivalent chromium plating, as well as the overall risk to human health and the environment is provided in Appendix 2.1.7.

6.7.2. Technical feasibility General assessment: The major advantage of Cr(III) plating is that it is closest to a “drop-in” replacement – compared to all other alternatives described in this dossier – for current chromium trioxide process technology as far as process type is concerned. Although the research to generate chromium layers out of Cr(III) compounds in aqueous solutions has been ongoing for more than 40 years, it cannot be considered as promising alternative for functional chrome plating. Results on R&D for Cr(III) metallic chrome coatings are mainly available from laboratory scale research. Almost no results are available on industrial application of Cr(III) based chrome plating applications, showing that Cr(III) as alternative for chromium trioxide is still under laboratory research.

Figure 24: Cross-section image from Cr(III) coatings in relation to layer thickness and to different spots located at the coated part (pfonline, 2013).

Microstructure: The microstructure of Cr(III) coatings shows unacceptable macro-cracks down to the substrate (Faraday, research project and Figure 24). This failure can significantly impair important key coating functionalities such as corrosion and wear resistance that have to be fulfilled by a chromium trioxide alternative.

Hardness: The achievable hardness of Cr(III) coatings is between 700 and 850 HV (Legg, 2003a) compared to the range for chromium trioxide functional chrome coatings between 700 and 1,400 HV. At MTU 800 -1,100 HV are required, which are not met by Cr(III) coatings.

Layer thickness: The deposition rate of some electrolytes decreases over longer plating times. The Cr(III) process takes approximately three times longer than the conventional chromium trioxide-based process to achieve the desired thickness (TURI, 2012). A large range for the key parameter layer thickness of 0.1 to 500 µm is stated in the literature. (NEWMOA, 2003; Legg, 2003a). The maximum literature values of up to 500 µm are not supported by evidence and experimental details. Even if Cr(III) layers up to 500 µm seem to be technically possible at laboratory scale, coating quality



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decreases with increasing thickness. The required layer thickness cannot be obtained while simultaneously maintaining the layer quality using Cr(III).

Wear resistance: Publicly available information from the ECOCHROM project stated that material loss for trivalent plated rapid steel is less than for chromium trioxide-plated steel. In a Faville wear test a loss of 72 mg/h was measured for standard chromium trioxide metallic chrome coatings compared to about 30 mg/h for Cr(III) (Négré, 2002). The results were measured for a complexed and a reduced Cr(III) solution in laboratory scale. However, there is no wear data for the behaviour of chrome coatings from trivalent electrolytes for aircraft engine components. Therefore it cannot be assumed that they can reach the wear resistance of today’s chromium coatings from chromium trioxide processes

Corrosion resistance: Currently, the Cr(III) coating will not provide corrosion resistance due to its tendency to form macro-cracks.

Process conditions: Cr(III) baths are more sensitive to metallic impurities and the acidity of the bath than chromium trioxide baths. Small deviations in these process conditions can strongly influence the deposition success and the layer quality (Legg, 2003a). The process window for Cr(III) plating lies in a very narrow pH range, which is difficult to maintain. Consequently, establishing a reliable process for Cr(III) coatings of reproducible quality is challenging and not yet technically feasible.

Concluding from all the facts presented above, the required layer thickness cannot be obtained while simultaneously maintaining the layer quality using Cr(III). Therefore, trivalent chrome plating is clearly not applicable for MTU’s purposes.

6.7.3. Economic feasibility As the process of trivalent chromium plating with high coating thicknesses is far from being technically feasible for aircraft engine components and MRO applications at MTU, no quantitative analysis of economic feasibility was conducted.

6.7.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances reported during the consultation were reviewed for comparison of hazard profile (see Appendix 2.1.7).

Based on the available information on the substances used within this alternative (see Appendix 2.1.7), Cr(III) chloride would be the worst case with a classification as Skin Irrit. 2, Eye Irrit. 2, Acute Tox. In general, the trivalent electroplating processes are less toxic than chromium trioxide plating due to the oxidation state of the chromium. Cr(III) solutions do not pose serious air emission issues, but still pose the problems of disposal of stripping solutions (depending on the type of stripping solution) and exposure of staff to chrome dust during grinding.

In addition, there is a certain risk of Cr(VI) being generated during plating process. This is why appropriate security precaution and process management has to be adopted to prevent the formation of Cr(VI). The bath chemistry typically also comprises a high concentration of boric acid, which is a SVHC substance (toxic for reproduction) included on the candidate list and currently on the 6th recommendation for inclusion in Annex XIV. Despite these facts, the transition from chromium trioxide to trivalent chromium constitutes a shift to less hazardous substances.

6.7.5. Availability The electroplating process based on Cr(III) bath chemistry as an alternative for chromium trioxide functional chrome plating is still in the early development stage. Tests are ongoing but Cr(III) is neither technically ready nor qualified to replace chromium trioxide functional chrome plating



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applications. Today the instable process conditions still lead to unreliable reproducibility and unacceptable microstructure with cracks down to the substrate.

The process exhibits low maturity for aeronautic applications. TRL for the Cr(III) based alternative remains low at this time. Further R&D is necessary to ensure process conditions and to meet the requirements of the key functionalities first in laboratory scale and then in functional field tests. However, certainly a further decade is required for R&D.

6.7.6. Conclusion on suitability and availability for alternative trivalent chrome plating The Cr(III) based electroplating systems do not perform as technically equivalent to chromium trioxide-based products and are therefore not an alternative for plating of aircraft engine components and MRO applications. Today the instable process conditions still lead to unreliable reproducibility and unacceptable microstructure with cracks down to the substrate.

To date there is no evidence that Cr(III) performs equally compared to chromium trioxide on the most important key functionalities hardness, layer thickness, wear and corrosion resistance for MTU’s applications. Certainly a further decade is required for R&D. But there is no guarantee whether trivalent chrome plating will then meet MTU’s requirements.

6.8. ALTERNATIVE 8: Physical vapour deposition (PVD)

6.8.1. Substance ID and properties PVD (Physical Vapour Deposition) is the general name for a variety of vacuum processes. They all start with the coating material in a solid (or rarely in a liquid) form placed in a vacuum or low pressure plasma environment. The coating material is vaporised and deposited, atom by atom, onto the surface of the substrate in order to build up a thin film. Vaporising of the coating material may be conducted by one of the following methods:

Vacuum evaporation: The coating (source) material is thermally vaporised in a vacuum and follows a “line-of-sight” trajectory to the substrate where it condenses out into a solid film. Vacuum evaporation is used for applications such as mirror coatings and barrier films on flexible packaging (TURI, 2006).

Ion assisted deposition / ion plating: This is a combined method as a film is deposited on the substrate while ion plating bombards the depositing film with energetic particles. The energetic particles may be the same material as the depositing film, or it may be a different inert (argon) or reactive (nitrogen) gas. Ion beam assisted deposition describes a process in a vacuum environment where the ions originate from an ion gun (TURI, 2006).

Sputtering: This process is a non-thermal vaporisation where the surface atoms on the source material are physically ejected from the solid surface by the transfer of momentum from bombarding particles. Typically the particle is a gaseous ion accelerated from low pressure plasma or from an ion gun (TURI, 2006). The conditions for PVD coatings are process specific and dependent on the substrate and applied coating. In general the method is not limited by substrate, in practice however, heat sensitive materials such as aluminium alloys and high strength steels are likely to be tempered because of elevated process temperatures (Legg, 2003a). PVD coating temperatures are typically in the range between 180°C to 450°C, but processes with lower and higher temperatures are also available. The coating time depends on a number of factors, such as coating thickness, spinning time of the part in the vacuum chamber, and the geometry of the part to be coated. In general, the throughput of parts depends on the size of the vacuum chamber and the geometry of the parts.



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Possible PVD coatings, applied as single or multi-layer, are based on e.g. titanium nitride (TiN), titanium-aluminium nitride (TiAlN), chromium nitride (CrN), diamond like carbon (DLC), titanium carbide (TiC), and tungsten carbide (WC, WC-H). DLC is a special coating and consists of combined bond types of graphite and diamond. DLC forms an amorphous diamond-like carbon layer, with hardness properties > 2,000 HV.

In addition to the mode of application, the material used in the process significantly influences the properties of the PVD coating. Therefore, the most promising materials for PVD-coatings are illustrated in the following assessment of the technical feasibility, which are WC-H, TiN and CrN based on R&D.

A non-exhaustive overview of general information and the identity of relevant substances used within this alternative and the risk to human health and the environment is provided in Appendix 2.1.8.

6.8.2. Technical feasibility PVD technology is an established technology at MTU. TiN and CrN are used as traditional PVD coatings e.g. for aerospace wear applications (as erosion or anti fretting coatings in some aircraft engines) and thermal barrier coatings.

Vacuum/Geometry/Partial coatings: The need of a vacuum chamber limits the size and the type of parts that can be coated. PVD, a line of sight process, is not suitable for complex geometries and large parts. Moreover, for aerospace applications the ability to plate defined areas on parts while most of the surface remains uncoated is required. This is not feasible with a PVD process, without disproportionate efforts. As the whole part that is to remain uncovered needs to be protected, more coating metal deposited on the cover than actually needed for the area to be coated.

Layer thickness / Rebuilding of parts: In most cases the ion bombardment during coating is responsible for high internal stress. This stress increases with increasing coating thickness and can lead to delamination of the coating. As a consequence, typical PVD layers are about 3–5 µm (in rare cases about 15 µm) thick. As overhaul and repair work require thicknesses exceeding 100 µm in order to be able to restore the original shape and function, PVD coatings are generally not suitable for rebuilding worn components.

Wear resistance: The wear resistance is one of the most important functional parameters of a metallic chrome coating. One company states that the wear resistance of PVD coatings is not higher under high load for TiN and tungsten carbide with amorphous carbon. However, some materials such as WC-C-H showed sufficient performance in fretting wear conditions for selected applications under low load conditions, due to the self-lubrication and low coefficient of friction. A wear rate of 6-10 mm³/nm for up to 300,000 cycles is reported against copper alloy parts. CoCrMo or Mo coatings have sufficient sliding wear properties against copper or steel counterparts. In Taber testing, the performance is better than for metallic chrome coatings (five times higher). Hardness: PVD coatings are characterised by uniform layers with higher hardness compared to chromium trioxide based coatings. The hardness of PVD coatings range from 1,200-2,400 HV, depending on the coating material. This performance covers the minimum requirement of 800-1,100 HV.

Deposition rate: According to information provided in the consultation within the CTAC consortium and MTU, PVD processes include low deposition rates compared to functional chrome plating (typically 1-4 µm/hour for PVD coatings, the maximum has been reported to be 10 µm/hour (Lin et al., 2011)). In combination with the high costs of PVD equipment, the coating costs increase with increasing coating thickness.



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Temperature: The process conditions for PVD require sub-atmospheric pressure and temperatures between 150 and 600°C. Process temperature, especially the upper limit, imposes restriction to the substrate materials that can be coated. Substrates where the max. processing temperatures are below the temperature needed for PVD, such as aluminium alloys (< 150°C) and high strength steel (< 250°C), are not suitable as they would melt away or be distorted.

Cleanliness: PVD coatings require an atomically clean surface because they are highly sensitive to contaminants (e.g. water, oils and paints) on the surface to be coated. In fact, inadequate or non-uniform ion bombardment leads to weak and porous coatings and is the most common cause of failure in PVD coating. Therefore, an extremely efficient cleaning and drying method is required for this process.

Corrosion resistance: PVD nitride coatings are reported to be essentially inert and do not corrode. However, test results show that tungsten carbide/carbon (WC-CH) and titanium nitride (TiN) do not offer sufficient corrosion resistance due to thin coating.

Coefficient of friction: Another critical parameter is the friction behaviour. Functional chrome plated surfaces achieve a stable coefficient of friction less than 0.2. Compared to the value that is achieved by metallic chrome coating, tungsten carbide with amorphous carbon seems to achieve the requirement, whilst the coefficient of friction of titanium nitride is too high.

6.8.3. Economic feasibility Against the background of significant technical failure of PVD, no quantitative analysis of economic feasibility was conducted. However, the cost for PVD depends on numerous different factors and these are presented in a qualitative to semi-quantitative way below.

The technology for PVD processes and functional chrome plating differ fundamentally in the equipment and peripherals. The implementation of PVD requires complex machines and infrastructure equipment. The installation costs for a completely new plant and machine lines are estimated to be about $1-3 million for the coating system, with additional costs for cleaning lines (Legg, 2012). During the consultation within the CTAC consortium, the investment costs for PVD processes were commented by companies to be very high whilst the implementation of the process represents a large business risk.

According to the aerospace sector the relative costs depend on batch requirements and the process. PVD is potentially less expensive than functional chrome plating for large batches of small components (e.g. drill bits) but is more expensive for small batches with large components, which definitely applies to MTU. The PVD process is complex and expensive because it requires vacuum, high temperatures, costly devices/tools, pre-treatment of the parts and skilled operators that are able to handle the machinery.

Due to a low deposition rate of the coating material (a few µm per hour), PVD is only suitable for low volume production.

6.8.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances and products reported during the consultation were reviewed for comparison of the hazard profile. Based on the available information on the substances used within this alternative (see Appendix 2.1.8), titanium nitride would be the worst case with a classification as Flam. Sol. 2, Skin Irrit. 2 and Eye Irrit. 2 As such, transition from chromium trioxide – which is a non-threshold carcinogen – to one of these substances would constitute a shift to less hazardous substances.



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6.8.5. Availability PVD process equipment is commercially available; and a well-known technology within and outside the EU. The PVD technology is currently used at MTU for thermal barrier coatings (via electron beam-PVD), anti-fretting or erosion coatings. As of today, the process is only feasible for these specific parts. Significant technical limitations such as the inability to rebuild parts and economic issues would need to be overcome to develop this into a general functional chrome plating alternative. This is not expected to take place within the next 15 years. For technical reasons, PVD is not an option to be used for MTU’s MRO purposes.

6.8.6. Conclusion on suitability and availability for alternative PVD Coatings applied by PVD do not perform as technically equivalent to chromium trioxide derived products and therefore are not a general alternative. The aerospace sector criticises failure in wear and corrosion resistance as well as the insufficient layer thickness which is needed for repair and overhaul works. The PVD process differs fundamentally from functional chrome plating. The implementation of PVD comes along with high investment costs.

In conclusion, the inability to rebuild worn parts disqualifies PVD coating for the application for MRO purposes and thus does not constitute a feasible alternative to functional chrome plating for MTU.

6.9. ALTERNATIVE 9: General laser coating technology

6.9.1. Substance ID and properties / process description General laser coating technology includes the following processes:

- Laser alloying - Laser cladding

The processes listed above are summarised as one alternative group, since they are all based on the same technology. These coating methods are in general very elaborate.

Laser alloying is a process in which material is integrated within the underlying surface. It diverges only from laser cladding in some process conditions, e.g. the power and length of the laser pulse. During laser cladding, material, such as metals and alloys in form of powder, wire etc., is fused onto the substrate surfaces to form a coating (Legg, 2003a). The processes offer a large choice of possible starting powders (pure metals, alloys, and carbides). Cladding of turbine blades at MTU is carried out with a similar-type powder corresponding to the base material.

General information of the exemplary chosen tungsten carbide cobalt coating and the risk to human health and the environment is provided in Appendix 2.1.9.

6.9.2. Technical feasibility Process temperature: Laser cladding requires high surface temperatures (> 500°C) in order to weld the materials together. As a result, heat-affected zones occur under the coating layer, increasing serious risks of overheating, crack building and early fatigue. This effect varies from one material to another. Due to the high temperatures and the risk of overheating, laser cladding is limited to materials that can take the process temperatures and is not suitable for general use, or for small or extensive coatings (Legg, 2003a).

Layer properties: Moreover, the weld material tends to crack during multiple coatings due to internal stress from repeated high heat and cool cycles in order to build up thicker layers.



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Process handling: The process is not easy to handle because the process window between alloying and cladding is too narrow to obtain constantly reliable coating results on diverse components.

Laser cladding is a line of sight process and is not suitable for extensive coatings, complex parts geometries or partial coating of parts. Especially for MRO purposes, laser cladding is therefore not a suitable general alternative to functional chrome plating.

6.9.3. Economic feasibility Against the background of significant technical failure of general laser coating technology, no quantitative analysis of economic feasibility was conducted.

6.9.4. Reduction of overall risk due to transition to the alternative As the alternative is not technically feasible, only classification and labelling information of substances (see Appendix 2.1.9) and products reported during the consultation were reviewed for comparison of the hazard profile.

As mentioned above, various different powder materials are used for these processes, for which some substances are confidential business information. Exemplarily, the hazard profile from an often-used coating material is illustrated. According to suppliers’ SDS, the following hazard statements are given for WC-12Co: Skin Irrit. 2, Eye Irrit. 2, STOT SE 3, Carc. 2. As such, transition from chromium trioxide – which is a non-threshold carcinogen – to WC-12Co would constitute a shift to significantly less hazardous substances. However, some cobalt compounds are on the REACH candidate list for substances of very high concern so an assessment on the hazardous profile of these substances would have to be performed on a case by case basis.

6.9.5. Availability Laser cladding is a commercially available process and used in production for cladding of turbine blades at MTU. The technology is not available as standard equipment or as a standard workshop process.

As all alternatives stated above are no like-for-like replacement for functional chrome plating and they are still in very early stage of R&D, a minimum of 15 years would be needed to develop a general metallic chrome coating alternative. However, there are other alternatives that show more potential to be used in the MRO business.

6.9.6. Conclusion on suitability and availability for alternative general laser coating technology

In conclusion, laser coating processes are not appropriate as replacement processes for functional chrome plating of aircraft engine parts and MRO applications at MTU.



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PRE-TREATMENT

After several alternatives for the main surface treatment have been assessed in the former chapters, alternatives for pre-treatment using chromium trioxide in the functional chrome plating process are discussed in the following. The purpose of the pre-treatment is the removal of surface residues. As there is no clear demarcation, the term etching is used to cover both, etching and pickling as chromium trioxide pre-treatment in the following.

6.10. Mineral acids

6.10.1. Substance ID and properties Different mineral acids are currently under evaluation as alternatives to chromium trioxide in the surface pre-treatment process. Research is currently focused on using sulphuric acid composed with other acids, such as phosphoric acid and nitric acid, or with additives, such as peroxymonosulphate salts or peroxidisulphate salts.

An overview of general information on substances used within this alternative and the risk to human health and the environment is provided in Appendix 2.2.

6.10.2. Technical feasibility

General assessment Pre-treatment is necessary to prepare the surface of the substrates for the subsequent process steps. Adequate preparation of the base metal is a prerequisite: adhesion between the metallic chrome coating and the substrate depends on the force of attraction at a molecular level. The surface of the metal – which is mostly steel or hardened steel for functional chrome plating – must be absolutely free of contaminants, corrosion and other residuals until the plating process is finished. The vast majority of non-mechanical pre-treatment processes are reverse etching processes using an aqueous solution of chromium trioxide in a separate etch bath. The same substance is used for pre-treatment and main treatment. Therefore, no additional rinsing working step involving water is required in between. Many applications require the usage of chromium trioxide in the pre-treatment working step, especially when the etch rates need to be strictly controlled and over-etching must be avoided. For example, the steel industry requires that the coating does not affect the surface morphology of the substrate. The defined surface texture of the substrate is created during the pre-treatment and must be kept during the plating process. The desired surface roughness varies for different applications in the range of 0.7 µm to 15 µm. Pre-treatment with chromium trioxide provides surface roughness in the application range as required. Alternatives must have analogous key functionalities to chromium trioxide, most importantly excellent adhesion promotion. In addition, if another substance than chromium trioxide is used in the pre-treatment process, cross contamination with the plating bath must be prohibited. Minor contamination with sulphur or chlorides are sufficient to make the plating bath content unsuitable for functional chrome plating needs and require to dispose of and exchange the bath content. Cross contamination is especially critical for parts with complex geometry, where residues of the pre-treatment solutions may be trapped in holes, openings, excavations, inside tubes, etc. Therefore, all parts must be thoroughly cleaned in additional working steps. If chromium trioxide is the only substance used for pre-treatment in manufacturing, no such cleaning installations are necessary. Furthermore, significant amounts of water are needed for the rinsing process which need to be adequately treated and discharged accordingly. Thus, appropriate water and waste water installations become mandatory. In summary, a diversity of additional equipment need to be



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implemented which fundamentally changes the existing facility design and require significantly more space. In addition, the alternative pre-treatment should be compatible with all relevant substrates. If alternatives are substrate specific, a separate pre-treatment bath with appropriate installation would be required. The use of one substance for both, pre-treatment and main treatment ensures high quality and smooth process functionality. The development of a pre-treatment alternative to chromium trioxide depends on the potential alternative for functional chrome plating and is no standalone process. While an alternative for functional chrome plating is investigated, adequate custom-tailored pre-treatments are evaluated in parallel or after the potential alternatives for the main process have been qualified.

Alternatives Sulphuric acid based solutions are assessed as a potential alternative for chromium trioxide-based etching pre-treatments on metal substrates. They are used at room temperature and the parts are not preheated. It is qualified for some applications and processes, but not as a general replacement for chromium trioxide pre-treatment. Sulphuric acid anodic etching has been used successfully for some steels but smutting can be an issue. Nickel strike solutions (usually NiCl2 / HCl) can be used as an alternative to back etching for many stainless steels, but nickel salts present very strong health and safety issues (CMR classification). As the performance of the subsequent functional chrome plating step is strongly linked to the pre-treatment process and to the type / chemical composition of the substrate being processed, the alternative does not currently prepare the surface equivalent to a chromium trioxide-based etching process and does not meet the requirements. Therefore, additional R&D is necessary to further adjust these processes. An etching solution of sulphuric acid with peroxymonosulphate (for example potassium peroxymonosulphate 2KHSO5·KHSO4·K2SO4) for different kinds of stainless steel was tested at ambient temperature at the laboratory scale. The etching process (removal of smut) showed rapid, suitable performance with regard to surface quality. Currently, this alternative is at a very early investigation state. A detailed visual examination is mandatory to ensure that no end grain pitting occurs on stainless steel. Conclusions: At the current stage, mineral acid based solutions are technically not feasible as a general alternative to chromium trioxide-based etching of metals. Intensive R&D efforts are ongoing to improve their performance, as the surface is not adequately prepared for the subsequent process step and the applied layers do not adequately adhere to the substrate. In addition, none of the evaluated alternative solutions are applicable for all the different kinds of metal substrates.

Assessment overview for pre-treatment with mineral acids

Adequate surface preparation Adhesion to the substrate Compatibility with substrates

6.10.3. Economic feasibility The economic feasibility of etching with mineral acid on metal substrates was not assessed, as the alternative is not technically feasible and already failed the requirements at early investigation stage.

Switching to a chromium trioxide-free etching alternative would generally necessitate the installation of additional bath equipment for rinsing processes. The larger the parts, the larger the separate pre-treatment baths and appropriate installations. For facilities producing large parts especially with



73

complex geometry, changes of the facility design and need for space consuming and expensive additional equipment are significant.

However, based on the literature research and consultations there is no indication that the discussed alternative is not economically feasible.

6.10.4. Reduction of overall risk due to transition to the alternative As the alternatives are not technically feasible, only classification and labelling information of substances and products reported during the consultation were reviewed for comparison of the hazard profile. Based on the available information on the substances used within this alternative (see Appendix 2.2), sulphuric acid would be the worst case with a classification as Skin Corr. 1A, Met. Corr. 1. As such, transition from chromium trioxide – which is a non-threshold carcinogen – to one of these substances would constitute a shift to less hazardous substances.

6.10.5. Availability For some applications and substrates, the use of sulphuric acid based solutions is qualified but not as a general replacement for the chromium trioxide pre-treatment. As stated during the consultation, the technical feasibility for pre-treatment of steel is not yet equivalent to the current chromium trioxide-based process. The etching pre-treatment has to be adapted according to the subsequent chromium trioxide-free electroplating alternative, which is also still under R&D. However, etching as a pre-treatment to adequately prepare the surface for the subsequent step is always performed in-line with the functional chrome plating step and it is not a stand-alone process.

As pre-treatment and main treatment using chromium trioxide are closely related, it will take considerable efforts to develop an alternative as pre-treatment for steel which meets all requirements.

6.10.6. Conclusion on suitability and availability for mineral acids The use of chromium trioxide in pre-treatment processes is state of the art for several metal substrates. The pre-treatment of steel is carried out in a separate chromium trioxide etch bath at MTU.

As potential alternative for pre-treatment of steel, sulphuric acid based solutions can be considered. The technical feasibility is not yet equivalent to the current process. The development of a pre-treatment alternative to chromium trioxide also depends on the potential alternative for functional chrome plating and is not a standalone process. While an alternative for functional chrome plating is investigated, adequate custom-tailored pre-treatments are evaluated in parallel or after the potential alternatives for the main process have been qualified. Therefore, the time needed for R&D and industrial implementation of an alternative are identical for pre-treatment and main treatment, which is a minimum of 15 years.



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7. OVERALL CONCLUSIONS ON SUITABILITY AND AVAILABILITY OF POSSIBLE ALTERNATIVES FOR FUNCTIONAL CHROME PLATING

In this AfA, a total of nine different alternatives have been considered for the purpose of functional chrome plating with chromium trioxide for coating of components for aircraft engines for civil and military uses at MTU. The company uses functional chrome plating for coating of components in course of MRO work on aircraft engines as well as new components for aircraft engines. Pre-treatment of steel using chromium trioxide has been assessed separately.

MRO is a central concept in the aerospace sector. Airplanes are usually designed to allow an overall lifetime of 20 to 30 years before they are finally taken out of service. An aircraft engine is exposed to extreme mechanical forces and temperatures as well as to conditions that give rise to hot gas corrosion. Therefore, the components of aircraft engines are subjected to wear, corrosion, oxidation, vibrations and fatigue, as the required performance of the parts inevitably suffers and, if adequate measures are not taken, can be subject to failures. Moreover there are so called "life limited parts" that are deliberately operated above their yield strength, for example compressor and turbine discs and blades. Thus, in order to maintain flight security, aircraft are subject to intensive MRO activities.

Functional chrome plating involves depositing a layer of metallic chromium on the surface of a metallic component, for example on steel, stainless steel, titanium alloys, nickel-/cobalt superalloys (cast and forged), copper alloys, and aluminium alloys, as applied at MTU. This metallic chrome coating provides the article with high mechanical and wear resistance, excellent anticorrosion performance and a low coefficient of friction. The process is therefore specified for particular applications where this combination of performance characteristics is critical.

As of today, only functional chrome plating using chromium trioxide offers the combination of all key functionalities that are required for technical applications or in parts that must perform under demanding conditions that involve high temperatures, repetitive wear and mechanical impact, as it is the case for aircraft components.

Functional chrome plating using chromium trioxide involves immersion of the component in each of a series of treatment baths containing chemical solutions or rinses under specific operating conditions and is normally the final step in the overall surface treatment process. Chromium trioxide is a pre-requisite for the main treatment of functional chrome plating to ensure the highest quality of the product and to meet the requirements of the industry. Chromium trioxide is also used in the pre-treatment processes, such as etching / pickling. To date, sulphuric acid based solutions are already qualified for most applications and substrates at MTU. For pre-treatment of steel, no alternative has been developed and industrialised yet at MTU. The time needed for R&D and industrial implementation of an alternative are identical for pre-treatment and main treatment, which is a minimum of 15 years. Generally, implementation of changes in the coating technology for components for aircraft engines in service is connected with considerably high additional efforts, due to the substantial role of flight security and is therefore only practicable in serious circumstances.

Some of the assessed technologies, such as thermal spray coatings, CVD, PVD or laser cladding are already in use at MTU, but not necessarily as an alternative to functional chrome plating. As of today, several technical limitations disqualify them from fully replacing functional chrome plating for MRO purposes as they do not provide the necessary combination of key functionalities required for MTUs application. Thermal spray coatings could potentially reduce the number of parts subjected to functional chrome plating for MRO activities, as outer diameters of simple geometry components can be coated. However, for key applications such as parts with complex geometries and small IDs the technology is not applicable. An intensive screening process is required in order to assess for which of the many components of an aircraft engine such alternative coatings are applicable.



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Table 11 provides an overview of the technical deficiencies on all category 1 alternatives where the parameters that failed the technical feasibility check are listed.

Table 11: Technical deficiencies of category 1 alternatives for MTU’s purposes.

Alternative Reasons why alternative cannot replace functional chrome plating at MTU

1 Thermal spray coatings

- Not feasible for small IDs and complex geometries - Adhesion not in line with requirements - Wear resistance (depends on the coating, loads, wear mechanisms and the

counterparts) - Corrosion resistance (depends on the coating material) - Hardness (depends on technology and coating material)


- Hardness - Wear resistance - Coefficient of friction - Microstructure - No significant shift towards less hazardous substances

3 Thick CVD

- Partial coatings not feasible - Layer thickness insufficient for MRO - Process temperature - Geometry: size limitation, not suitable for large parts


- Hardness - Wear resistance about 10 times lower compared to functional chrome plating - Partial coatings not feasible - No shift to significantly less hazardous substances - No experience with the alternative at MTU

Review period Extensive evaluation of potential alternatives to chromium trioxide-based functional chrome plating, in aerospace applications for civil and military uses is carried out in the present AoA. Furthermore, economic aspects, as well as aspects of approval and release in the aerospace sector are assessed with regard to a future substitution of the substance. The following key points are relevant for derivation of the review period:

- Based on experience and with reference to the status of R&D programmes, implementation of feasible alternatives for key aircraft engine components and MRO applications at MTU is not foreseen to be finalised within 15 years after sunset date (Chapter 6).

- Any candidate alternative is required to pass full qualification, certification and implementation/industrialisation to comply with very high standards in the aerospace sector regarding airworthiness and flight security to ensure safety of use (Chapter 4).

- The European aviation industry, in general, requires optimal framework conditions in order to maintain its competitiveness, its high technological standards and to preserve/generate jobs. Long lifecycles of commercial engine programmes are linked to long investment cycles. Starting from the R&D kick-off of a new commercial engine programme, approximately 15 years are required on average to reach return on investment (ROI), while aircraft engine production periods may be more than 30 years. Maintenance and repair activities are required even after end of production (Chapter 4.7).

- The socio-economic impacts of a non-granted authorisation, amounting to € 1,221.6 million, outweigh the monetised residual risk to human health and the environment of a granted authorisation of € 76,894 (refer to the SEA).

As a consequence of the aforementioned circumstances, a review period of 15 years is selected because it coincides with best case estimates by MTU of the schedule required to industrialise alternatives to chromium trioxide.



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8. REFERENCE LIST

Daly, B.P., Barry, F.J. (2003): Electrochemical Nickel-Phosphorus Alloy Formation. IoM Communications Ltd and ASM International.

Di Bari, G.A. (2010): University of California Santa Barbara: Electrodeposition of Nickel.

Facchini, D., Mahalanobis, N., Gonzalez, F., Palumbo, G. (2009): Electrodeposition of Nanocrystalline Cobald Alloy Coatings as a hard Chrome Alternative, Integran Technologies.

Faraday Technology Inc., research project.

Gonzales, P. (2010): Electroplate Alternatives to Hard Chrome: Nanocrystalline Metals and Alloys, presentation.

Holeczek, H. et al. (2011): Report on Inclusion of Chromium Trioxide (CrO3) in Annex XIV, final report.

Hu, C.-C. (2000): Electrodeposition of Nickel-Phosphorus Deposits with a Variable Magnetic Property. (https://www.electrochem.org/dl/ma/198/pdfs/0636.pdf as of 09/30/14).

Legg, K., Sauer, J. (2000): Use of Thermal Spray as an Aerospace Chrome Plating Alternative, final report.

Legg, K. (2001) Replacement of Hard Chrome Plating (http://www.asetsdefense.org/documents/DoDBriefings/CrPlatingAlts/Replacement%20of%20hard%20chrome%20plating,%202001.pdf).

Legg, K. (2003a): Chrome Replacements for Internals and Small Parts, final report (http://www.asetsdefense.org/documents/DoD-Reports/Cr_Plating_Alts/Cr_Rplcmnt-IDs&Sm_Parts.PDF).

Legg, K. (2003b): Chromium and Cadmium Replacement Options for Advanced Aircraft, HCAT Programme Review, KSC.

Legg, K. (2012): Choosing a Hard Chrome Alternative (http://www.rowantechnology.com/wp-content/uploads/2012/06/Hard-Chrome-Plating-Alternatives.pdf).

Lin, J., Sproul, W. D., Moore, J. J., Lee, S., Myers, S.(2011): High Rate Deposition of thick CrN and Cr2N Coatings using Modulated Pulse Power (MPP) Magnetron Sputtering. Surface & Coating Technology, Elsevier, USA.

McCrea, J. L., Marcoccia, M., Limoges, D. (2003): Electroformed Nanocrystalline Coatings: an Advanced Alternative to Hard Chromium Electroplating, final report.

NDCEE (National Defense Center for Environmental Excellence) (1995): Regulatory Analysis of the Chromium Electroplating Industry and Technical Alternatives to Hexavalent Chromium Electroplating, USA, Environmental Information Analysis, final report.

Négré, P. (2002): HCT Meeting, Hard Chrome Alternatives Team (presentation).

NEWMOA (Northeast Waste Management Officials’ Association) (2003): Pollution Prevention Technology Profile, Trivalent Chromium replacements for Hexavalent Chromium Plating.

The Massachusetts Toxics Use Reduction Institute (2006): Five Chemicals Alternative Assessment Study.

TURI (Toxic Use Reduction Institute) (2012): Trivalent Chromium Plating Conversion Case Study: Independent Plating, Worcester, Massachusetts.

US Department of Defense (2009): ESTCP - Cost and Performance Report (WP-0127): Replacement of Chromium Electroplating on Helicopter Dynamic Components Using HVOF Thermal Spray Technology.

Watson, S. (1990): AlecNickel Electroplating Solutions, NiDI technical Series N° 10 047, Nickel Development Institute.

https://www.electrochem.org/dl/ma/198/pdfs/0636.pdf

http://www.asetsdefense.org/documents/DoDBriefings/CrPlatingAlts/Replacement%20of%20hard%20chrome%20plating,%202001.pdf

http://www.asetsdefense.org/documents/DoDBriefings/CrPlatingAlts/Replacement%20of%20hard%20chrome%20plating,%202001.pdf

http://www.asetsdefense.org/documents/DoD-Reports/Cr_Plating_Alts/Cr_Rplcmnt-IDs&Sm_Parts.PDF

http://www.rowantechnology.com/wp-content/uploads/2012/06/Hard-Chrome-Plating-Alternatives.pdf

http://www.rowantechnology.com/wp-content/uploads/2012/06/Hard-Chrome-Plating-Alternatives.pdf



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Internet sources:

1. http://www.epa.gov

2. Pfonline 2013: http://www.pfonline.com/articles/functional-trivalent-chromium-electroplating-of-internal-diameters (accessed on 17.06.2014)

3. www.werkstoffoberflaeche.de

4. http://sci.esa.int/

5. http://www.sulzer.com

6. http://epp.eurostat.ec.europa.eu

7. http://www.roymech.co.uk

8. http://echa.europa.eu

9. www.partsfinishing.com/

10. http://www.scbt.com

11. http://www.epa.gov/

12. www.turi.org/

13. http://ammtiac.alionscience.com/

14. READE internet site: http://www.reade.com

15. Chemie.de internet site: http://www.chemie.de/lexikon/Titannitrid.html

16. MAK Collection for Occupational Health and Safety: http://onlinelibrary.wiley.com

17. Merck SDS: http://www.merck-performance-materials.com

18. http://www.hardide.com/

19. http://echa.europa.eu/documents/10162/13552/aviation_authorisation_final_en.pdf

20. http://www.sifcoasc.com/wp-content/uploads/Nickel-Tungsten-5711.pdf

21. http://www.asetsdefense.org/documents/Workshops/ASETS2012/7/Clouser%20-%20For%20Web.pdf

22. http://www.myvirtualpaper.com/doc/nasf_aesf/pasf_may10/2010052701/52.html#52

23. NTSB: http://www.ntsb.gov/_layouts/ntsb.aviation/index.aspx

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http://www.merck-performance-materials.com/merck-ppf/detailRequest?unit=CHEM&owner=MDA&productNo=102487&language=DE&country=DE&docType=MSD&source=GDS&docId=/mda/chemicals/msds/de-DE/102487_SDS_DE_DE.PDF

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http://www.myvirtualpaper.com/doc/nasf_aesf/pasf_may10/2010052701/52.html#52



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APPENDIX 1 – MASTERLIST OF ALTERNATIVES WITH CLASSIFICATION INTO CATEGORIES 1-3 AND SHORT SUMMARY OF THE REASON FOR CLASSIFICATION OF ALTERNATIVES INTO CATEGORY 3 (SELECTION PROCESS)

Chapter Alternative Substance/ Alternative Process Category Screened out because

6.1

Thermal spray coatings /HVOF CrC-NiCr, WC-Co, WC-Co-Cr, Co-Cr-Mo, Mo /HVAF /detonation spraying /arc Spraying /cold gas spraying /flame spray coating -wire flame spraying -powder flame spraying /molybdenum thermal sprayed coatings

1

6.2

Nickel & nickel alloy electroplating /nickel-tungsten-boron, nickel-tungsten-silicon-carbide, tin-nickel, nickel-iron-cobalt, nickel-tungsten-cobalt, nickel tungsten, Fe-Ni-Cr

1

6.3

CVD (thick) /Chemical Vapour Deposition (CVD): TiN, WC, ZrN /Plasma enhanced Chemical Vapour Deposition Coating (PECVD)

1

6.4 (Nano) Co-P plating /cobalt electrolysis /(Nano) Co-P plating

1

6.5

Electroless nickel plating /nickel-tungsten, nickel-boron, nickel diamond composite, nickel-phosphorous, nickel-polytetrafluoretyhlene; Ni-SiC /NiP-PTFE

2

6.6

Case hardening (carburising, carbo nitriding, cyaniding, boronising, nitriding) /plasma diffusion: plasma nitriding, nitrocarburising, low pressure nitiriding /explosive hardening

2

6.7 Cr(III) based processes 2

6.8

PVD /Physical Vapour Deposition (PVD) techniques: Cr, CrC, CrN, MoS2, SiC, TiAlN, TiN,

2



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Chapter Alternative Substance/ Alternative Process Category Screened out because

WC-C:H, ZrN, Zr oxides, organic zirconates /DLC (PVD technique)

6.9 Laser coating technology /Laser alloying and laser cladding (NiC)

2

- Stainless steel & HSS 3

The use of stainless steel or HSS for whole component parts is not an option for aerospace applications, since the use of lightweight materials is a definite requirement that cannot be met by this alternative.

- Ion implantation 3

Ion implantation is not working as stand-alone replacement for functional chrome plating as no additional layer is applied and the surface is not rebuilt to its original layer thickness and rebuilding parts can thus not be reworked. In addition, the process has to be conducted under vacuum conditions which is not feasible for large parts.

- Iron-phosphor coating 3 Salt spray tests for iron phosphor coatings showed decomposition of the layer leading to severe substrate corrosion.

- Cobalt-tin plating 3 Cobalt-tin plating is mainly used for decorative applications and not for functional chrome plating.

- Zinc-based materials (zinc, zinc-tin, zinc-aluminium, zinc-nickel based passivation, non-electrolytic zinc plating)

3

Zinc is a “soft” metallic material with hardness values below 450 HV and therefore not a metallic chrome coating alternative. Zinc-based coating materials show insufficient performance in corrosion and wear resistance, and the coefficient of friction.



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APPENDIX 2 – INFORMATION ON SUBSTANCES USED IN ALTERNATIVES

APPENDIX 2.1 - ELECTROPLATING ALTERNATIVES (MAIN PROCESS)

APPENDIX 2.1.1: ALTERNATIVE 1: Thermal spray coatings

Table 1: Substance ID and properties for an exemplary tungsten carbide-cobalt coating.

Parameter Value Physicochemical properties Value

Chemical name and composition WC-12Co Physical state at 20°C and

101.3 kPa Solid (grey, odourless)

EC number Multiple components Melting point 3,410°C

CAS number Multiple components Density -

IUPAC Name Multiple components Vapour Pressure -

Molecular Formula Multiple components Water solubility Insoluble in water

Molecular weight Multiple components Flammability Flash Point

- -

Table 2: Hazard classification and labelling overview.

Substance Name Hazard Class and Category Code(s)

Hazard Statement Code(s) (labelling)

Number of Notifiers

Additional classification and labelling comments

Regulatory and CLP status

WC-12Co (commercially available product; Multiple component System)

Skin Irrit. 2, Eye Irrit. 2, STOT SE 3, Carc. 2

-

According to suppliers’ SDS, the following hazard statements are given: May cause eye and skin irritation. Contains Material that may cause target organ damage (based on animal data) Possible cancer hazard-contains material which may cause cancer (based on animal data).

Substance is not REACH registered. Hazard information from suppliers’ SDS.

APPENDIX 2.1.2: ALTERNATIVE 2: Nickel and nickel alloy electroplating

Table 1: Substance IDs and properties for relevant substances in nickel and nickel alloy electroplating.


Chemical name and composition

Boric acid (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (crystalline, odourless)



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EC number 233-139-2 Melting point No melting point detected below 1,000°C

CAS number 10043-35-3 Density 1.49 g/cm3

IUPAC name Boric acid Vapour pressure 9.90 . 10-8 kPa (25 °C)

Molecular formula B(OH)3 Water solubility 48.40 g/L (20°C, pH = 3.6)

Molecular weight 61.83 g/mol Flammability Flash Point:

Non flammable -


Nickel sulphate (mono constituent substance)

Physical state at 20°C and 101.3 kPa

Solid (greenish-yellow, anhydrous form)

EC number 232-104-9 Melting point ≥ 840°C (anhydrous form decomposes at 848°C)


IUPAC name nickel(2+) sulphate Vapour pressure -

Molecular formula NiSO4 Water solubility ≥ 625 g/L

Molecular weight 154.8 g/mol Flammability Flash Point

- -



Nickel dichloride (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid

EC number 231-743-0 Melting point 1,001°C


IUPAC name nickel(2+) dichloride Vapour pressure -

Molecular formula NiCl2 Water solubility -


Non flammable -

Table 2: Hazard classification and labelling.



Number of Notifiers



Boric acid (CAS 10043-35-3) (EC 233-139-2)

Repr. 1B

H360FD (May damage fertility. May damage the unborn child)

n/a -

REACH registered; Harmonised classification- Annex VI of regulation (EC) No 1272/2008 (CLP Regulation); index



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Number of Notifiers



number: 005-007-00-2. Included according to Annex XVI on the candidate list (SVHC substance)

Nickel sulphate (CAS 7786-81-4) (EC 232-104-9)

Acute Tox. 4 Skin Irrit. 2 Skin Sens. 1 Acute Tox. 4 Resp. Sens. 1 Muta. 2 Carc. 1A Repr. 1B STOT RE 1 Aquatic Acute 1 Aquatic Chronic 1

H 302 (harmful if swallowed) H 315 (Causes skin irritation) H 317 (may cause allergic skin reaction) H 332 (harmful if inhaled) H 334 (may cause allergy or asthma symptoms or breathing difficulties) H 341 (suspected of causing genetic defects) H 350 I (may cause cancer by inhalation) H 360D (may damage the unborn child) H 372 (causes damage to organs) H 400 (very toxic to aquatic life) H 410 (very toxic to aquatic life with long lasting effects)

kin Sens. 1; H317: C ≥ 0,01% STOT RE 1; H372: C ≥ 1% Skin Irrit. 2; H315: C ≥ 20% M=1 STOT RE 1; H373: C ≥ 1% STOT RE 2; H373: 0,1% ≤ C < 1%

REACH registered; Harmonised classification- Annex VI of regulation (EC) No 1272/2008 (CLP Regulation); Index number: 028-009-00-5.

Nickel dichloride (CAS 7718-54-9) (EC 231-743-0)


H 301 (toxic if swallowed) H 315 (causes skin irritation) H 317 (may cause an allergic skin reaction) H 331 (Toxic if inhaled) H 334 (may cause an allergy or asthma symptoms or breathing

Skin Irrit. 2; H315: C ≥ 20% Skin Sens. 1; H317: C ≥ 0,01% STOT RE 2; H373: 0,1% < C < 1% M=1 STOT RE 1; H373: C ≥ 1% STOT RE 1; H372: C ≥ 1%

Harmonised Classification- Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Index Number: 028-011-00-6.



83



Number of Notifiers



difficulties if inhaled) H 334 (suspected of causing genetic defects) H 350i (may cause cancer by inhalation) H 360D (may damage the unborn child) H 372 (causes damage of organs) H 400 (very toxic to aquatic life) H 410 (very toxic to aquatic life with long lasting effects)

APPENDIX 2.1.3: ALTERNATIVE 3: Chemical vapour deposition

Table 1: Substance IDs and physicochemical properties.



Titanium carbide (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (crystalline)



IUPAC name Titanium carbide Vapour pressure -

Molecular formula TiC Water solubility Insoluble (< 0.1 mg/L)


Non flammable -



Titanium nitride (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (brown)



IUPAC name Titanium nitride Vapour pressure -

Molecular formula TiN Water solubility Insoluble in Water


Non flammable -




84


Chemical name and composition Titanium carbonitride Physical state at 20°C and 101.3

kPa powder

EC number 603-147-4 Melting point > 350°C

CAS number 12654-86-3 Density 5.08 g/ cm3 (at 25°C)

IUPAC name Titanium carbonitride Vapour pressure -

Molecular formula CNTi2 (TiC/TiN) Water solubility -


- -


Chemical name and composition Titanium silicon carbide Physical state at 20°C and 101.3

kPa Powder

EC number - Melting point -

CAS number - Density 4.53 g/cm3

IUPAC name - Vapour pressure -

Molecular formula Ti3SiC2 Water solubility -

Molecular weight - Flammability Flash Point

-



Titanium boride (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (powder, grey)



IUPAC name Titanium diboride Vapour pressure -

Molecular formula B2Ti Water solubility 0.074 mg/L (at 30°C)


Non flammable -



Aluminium oxide (mono constituent substance)


Powder (colourless, crystalline)


CAS number 1344-28-1 Density 3.97-3.99 g/cm3

IUPAC name oxo(oxoalumanyloxy)alumane Vapour pressure 1.33 hPa (at 2158°C)

Molecular formula Al2O3 Water solubility 2.00.10-5 g/L (at 20°C)


- -




85


Chemical name and composition Chromium nitride Physical state at 20°C and 101.3

kPa Powder (black)


CAS number 24094-93-7 Density 5.90 g/cm³

IUPAC name azanylidynechromium Vapour pressure -

Molecular formula CrN Water solubility Insoluble


- -

Table 2: Classification and labelling of relevant substances.

Substance Name

Hazard Class and Category Code(s)


Number of Notifiers



Titanium Carbide (CAS 12070-08-5) (EC 235-120-4)

Not classified 18

Notified classification Flam. Sol H 228 (flammable

Solid) 1

Titanium nitride (CAS 25583-20-4 ) (EC 247-117-5)

Not classified 11

Notified classification Flam. Sol. 2 Skin Irrit. 2 Eye Irrit. 2

H 228 (flammable Solid) H 315 (causes skin irritation) H 319 (causes serious eye irritation)

10

Titanium carbo nitride (CAS 12654-86-3) (EC 603-147-4)

Not available

According to suppliers’ SDS this substance is not classified according to EG Nr. 1271/2008.

Titanium silicon carbide (CAS -) (EC -)

not available

No Information on classification and labelling are available.

Titanium diboride (CAS 12045-63-5) (EC 234-961-4)

Acute Tox. 4 Acute Tox. 4 Acute Tox. 4

H 302 (harmful if swallowed) H 312 (harmful in contact with skin) H332 (harmful if inhaled)

120 Notified classification and labelling.

Aluminium oxide

Not classified 1649 Additional notification are available

Notified classification and labelling. Stot SE 3 H370 (Causes damage

to organs) 44



86

Substance Name



Number of Notifiers



(CAS 1344-28-1) (EC 215-691-6)

Acute Tox. 4 STOT SE 3

H 332 (harmful if inhaled) H 335 (may cause respiratory irritation)

34

Chromium nitride (CAS 24094-93-7) (EC 246-016-3)

Not classified 3

Pre registered substance; notified classification and labelling according to CLP criteria.

APPENDIX 2.1.4: ALTERNATIVE 4: Nanocrystalline cobalt phosphorus alloy coating



Chemical name and composition Orthophosphoric acid Physical state at 20°C and

101.3 kPa Liquid, colourless, viscous

EC number 231-633-2 Melting point 41.10°C (101 kPa)

CAS number 7664-38-2 Density 1.87 g/cm³ (20°C)

IUPAC name Phosphoric acid Vapour pressure 4 Pa (20°C)

Molecular formula H3PO4 Water solubility 5,480 g/L (cold water, pH = 0.5)


- -


Chemical name and composition Cobalt dichloride Physical state at 20°C and

101.3 kPa Solid, crystalline

EC number 231-589-4 Melting point 737°C


IUPAC name Cobalt(II)dichloride Vapour pressure 100 hPa (at 818°C)

Molecular formula CoCl2 Water solubility 585.90 g/L (20°C, pH = 7)


- -



87

Table 2: Hazard classification and labelling

Substance Name



Number of Notifiers



Orthophosphoric acid (EC 231-633-2) (CAS 7664-38-2)

Skin Corr. 1B, 1C Eye Dam. 1 Acute Tox. 4 STOT SE 3

H314 (Causes severe skin burns and eye damage) H318 (Causes serious eye damage) H312 (Harmful in contact with skin) H335 (May cause respiratory irritation) H302 (Harmful if swallowed)

52 -

REACH registered. Harmonised Classification- Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Index Number: 015-011-00-6

Cobalt(II) dichloride (EC 231-589-4) (CAS 7646-79-9)

Acute Tox. 4 Skin Sens. 1 Resp. Sens. 1 Muta. 2 Carc. 1B Repr. 1B Aquatic Acute 1 Aquatic Chronic 1

H302 (Harmful if swallowed) H317 (May cause an allergic skin reaction) H334 (May cause allergy or asthma symptoms or breathing difficulties if inhaled) H341 (Suspected of causing genetic defects) H350i (May cause cancer by inhalation) H360F (May damage fertility) H400 (Very toxic to aquatic life) H410 (Very toxic to aquatic life with long lasting effects)

26 -




88

APPENDIX 2.1.5: ALTERNATIVE 5: Electroless plating

Table 1: Substance IDs and properties.



Nickel sulphate (mono constituent substance)


Solid (greenish-yellow, anhydrous form)

EC Number 232-104-9 Melting point ≥ 840°C (anhydrous form decomposes at 848°C)

CAS Number 7786-81-4 Density 3.68 g/cm3

IUPAC name nickel(2+) sulphate Vapour pressure -

Molecular formula NiSO4 Water solubility ≥ 625 g/L

Molecular weight 154.8 g/mol Flammability Flashpoint

- -


Chemical name and composition Sodium phosphinate Physical state at 20°C and 101.3

kPa Solid (white)

EC Number 231-669-9 Melting point Substance decomposes at T≥ 238°C.

CAS Number 7681-53-0 Density 1.77 g/cm3

IUPAC name Sodium phosphinate Vapour pressure -

Molecular formula NaPH2O2 Water solubility 909 g/L (at 30°C, pH 5.8-5.9)


Non flammable -



Sodium borhydride (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (white, granular)

EC Number 241-004-4 Melting point > 360°C

CAS Number 16940-66-2 Density 1.080 g/cm³ (at 20°C)

IUPAC name Sodium tetrahydroborote Vapour pressure < 5.4 x 10-5 Pa (at 25°C)

Molecular formula NaBH4 Water solubility -


Not highly flammable -



89


Substance Name



Number of Notifiers



Nickel sulphate (CAS 7786-81-4) (EC 232-104-9)


H 302 (harmful if swallowed) H 315 (Causes skin irritation) H 317 (may cause allergic skin reaction) H 332 (harmful if inhaled) H 334 (may cause allergy or asthma symptoms or breathing difficulties) H 341 (suspected of causing genetic defects) H 350 I (may cause cancer by inhalation) H 360D (may damage the unborn child) H 372 (causes damage to organs) H 400 (very toxic to aquatic life) H 410 (very toxic to aquatic life with long lasting effects)

Skin Sens. 1; H317: C ≥ 0,01% STOT RE 1; H372: C ≥ 1% Skin Irrit. 2; H315: C ≥ 20% M=1 STOT RE 1; H373: C ≥ 1% STOT RE 2; H373: 0,1% ≤ C < 1%


Sodium hypophosphite (CAS 7681-53-0) (EC 231-669-9)

Not classified 326

REACH registered; Not included in the CLP Regulation, Annex VI; Included in C&L inventory

Eye Irrit. 2 H 319 (causes serious eye irritations 56

Skin Irrit. 2 H 315 (causes skin irritation) 23



90

Substance Name



Number of Notifiers



Sodium borhydride (CAS 16940-66-2) (EC 241-004-4)

Water react. 1 Acute Tox. 3 Acute Tox. 3 Skin Corr. 1B

H 260 (In contact with water releases flammable gases which may ignite spontaneously) H 301 (toxic if swallowed) H 311 (toxic in contact with skin) H 314 (causes severe skin burns and eye damage)

105


Water react. 1 Acute Tox. 3 Acute Tox. 3 Skin Corr. 1B Eye Dam. 1

H 260 (In contact with water releases flammable gases which may ignite spontaneously) H 301 (toxic if swallowed) H 311 (toxic in contact with skin) H 314 (causes severe skin burns and eye damage) H 318 (causes serious eye damage)

93

APPENDIX 2.1.6: ALTERNATIVE 6: Case hardening: Carburising, carbonitriding, cyaniding, nitriding, boronising.




Sodium cyanide (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (white, odourless)

EC number 205-599-4 Melting point 591°C (1.013 hPa)

CAS number 143-33-9 Density 1.595 g/cm³ (at 20°C)

IUPAC name Sodium cyanide Vapour pressure 0.10 kPa (at 800°C)

Molecular formula NaCN Water solubility 390 g/L (at 20°C)


- -




91



potassium cyanide (mono constituent substance)


Solid (white, odourless when dry)

EC number 205-792-3 Melting point 634.5°C (1.013 hPa)


IUPAC name Potassium cyanide Vapour pressure -

Molecular formula KCN Water solubility 400 g/L (at 20°C)


- -



Carbon monoxide (mono constituent substance)

Physical state at 20°C and 101.3 kPa Gaseous (odourless)

EC number 211-128-3 Melting point -199°C


IUPAC name Carbon monoxide Vapour pressure 20,664,910 hPa (at 25°C)

Molecular formula CO Water solubility 21.4 ml/L (at 25°C)

Molecular weight 28.01 g/mol

Flammability Flash Point:

≥ 10.9% lower flammability limit in air ≥ 77.6% upper explosion limit -



Ammonia (mono constituent substance)


Gaseous (colourless, odourless)

EC number 231-635-3 Melting point -77.7°C

CAS number 7664-41-7 Density -

IUPAC name ammonia Vapour pressure 8,611 hPa (at 20°C)

Molecular formula NH3 Water solubility 482 g/L (at 25°C)


≥ 16% Lower explosion limit ≥ 25% upper explosion limit -



Boron (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (odourless, black)

EC number 231-151-2 Melting point 2,075°C (1,013 hpa)


IUPAC name boron Vapour pressure -



92


Molecular formula B Water solubility Insoluble (< 0.1 mg/L)

Molecular weight[2] 10.81 g/mol Flammability Flash Point:

Non flammable -




Number of Notifiers



Sodium cyanide (CAS 143-33-9) (EC 205-599-4)

Acute Tox. 2 Acute Tox. 1 Eye Dam. 1 Acute Tox. 2 Aquatic Acute 1 Aquatic Chronic 1

H300 (Fatal if swallowed) H310 (fatal in contact with skin) H318 (causes serious eye damage) H330 (fatal if inhaled) H400 (very toxic to aquatic life) H410 (very toxic to aquatic life with long lasting effects)

94


Potassium cyanide (CAS 151-50-8) (EC 205-792-3)

Acute Tox. 2 Acute Tox. 1 Acute Tox 2 Aquatic Acute 1 Aquatic Chronic 1

H300 (Fatal if swallowed) H310 (fatal in contact with skin) H330 (fatal if inhaled) H400 (very toxic to aquatic life) H410 (very toxic to aquatic life with long lasting effects)

58

Acute Tox. 2 Acute Tox. 1 Skin Irrit. 2 Eye Dam. 1 Acute Tox. 1 STOT SE 1 STOT RE 1 Aquatic Acute 1 Aquatic Chronic 1

H300 (Fatal if swallowed) H310 (fatal in contact with skin) H315 (causes skin irritation) H318 (causes serious eye damage) H330 (fatal if inhaled) H370 (causes damage to organs) H372 (causes damage to organs trhough prolonged

47



93



Number of Notifiers



or repeated exposure)

Carbon monoxide (CAS 630-08-0) (EC 211-128-3)

Press. Gas Flam. Gas 1 Acute Tox. 3 Repr. 1A STOT RE 1

H220 (extremely flammable gas) H331 (toxic if inhaled) H360D (may damage the unborn child) H372 (causes damage to organs)

Harmonised Classification- Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Index Number: 006-001-00-2

Ammonia (CAS 7664-41-7) (EC 231-635-3)

Press Gas Flam. Gas 2 Skin Corr. 1B Acute Tox. 3 Aquatic Acute 1

H221 (flammable gas) H314 (causes severe skin burns and eye damage) H331 (toxic if inhaled) H400 (very toxic to aquatic life)

Harmonised Classification- Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Index Number: 007-001-00-5

Boron (CAS 7440-42-8) (EC 231-151-2)

Not classified - 120


APPENDIX 2.1.7: ALTERNATIVE 7: Trivalent hard chromium

Table 1: Substance ID and physicochemical properties



Chromium trichloride hexahydrate

Physical state at 20°C and 101.3 kPa Solid (green)

EC number - Melting point 80-83°C

CAS number 10060-12-5 Density -

IUPAC name Chromium(III) chloride hexahydrate Vapour pressure -

Molecular formula CrCl3 · 6H2O Water solubility 590 g/L (at 20°C)

Molecular weight 266.45 g/mol Flammability Flash point

Non flammable -




94



Boric acid (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (crystalline, odourless)

EC number 233-139-2 Melting point No melting point detected below 1,000°C


IUPAC name Boric acid Vapour pressure 9.90 . 10-8 kPa (25 °C)

Molecular formula B(OH)3 Water solubility 48.40 g/L (20°C, pH = 3.6)


Non flammable -



Chromium potassium bi(sulphate)

Physical state at 20°C and 101.3 kPa Solid (purple red)

EC number - Melting point 89.0°C


IUPAC name Chromium(3+) potassium sulphate hydrate (1:1:2:12)

Vapour pressure -

Molecular formula CrKS2O8 .12 H2O Water solubility 250 g/L


Non flammable -



Formic acid (mono constituent substance)

Physical state at 20°C and 101.3 kPa Liquid

EC number 200-579-1 Melting point 4.0°C

CAS number 64-18-6 Density 1.22 g/cm3 (at 20°C)

IUPAC name Formic acid Vapour pressure 42.71 hPa (20°C)

Molecular formula CH2O2 Water solubility Miscible in any ratio


Flammable 49.5°C (at 1,013 hPa)



Ammonium sulphamidate

Physical state at 20°C and 101.3 kPa Solid (colourless)

EC number 231-871-7 Melting point 131-135°C


IUPAC name Ammonium sulphamate Vapour pressure -

Molecular formula H6N2O3S Water solubility 1,666 g/L



95



Non flammable -


Chemical name and composition Ammonium chloride Physical state at 20°C and

101.3 kPa Solid (crystalline)

EC number 235-186-4 Melting point 340°C (sublimation)

CAS number 12125-02-9 Density 1.53 g/cm3 (at 20°C)

IUPAC name Ammonium chloride Vapour pressure -

Molecular formula NH4Cl Water solubility 283 g/L (25°C)


Non flammable -

Table 2: Classification and labelling of relevant substances.

Substance Name



Number of Notifiers



Chromium trichloride hexahydrate (CAS 10060-12-5)

Skin Irrit. 2 Eye Irrit. 2 STOT SE 3

H 315 (causes skin irritation) H 319 (causes serious eye irritation) H 335 (may cause respiratory irritation)

30

Substance is not REACH registered. Not included in the CLP Regulation, Annex VI; Included in C&L inventory

Acute Tox.TOX 4

H 302 (ha rmful if swallowed)

24

Chromium potassium bi(sulphate) dodecahydrate (CAS 7788-99-0)

Skin Irrit. 2 Eye Irrit. 2

H 315 (causes skin irritation) H 319 (causes serious eye irritation)

5

Pre-registered substance Not included in the CLP Regulation, Annex VI; Included in C&L inventory

Formic acid (CAS 64-18-6 (EC 200-579-1)

Skin Corr 1A

H 314 (causes severe skin burns and eye damage)

Skin Corr. 1A; H314: C ≥ 90% Skin Corr. 1B; H314: 10% ≤ C < 90% Skin Irrit. 2; H315: 2% ≤ C < 10% Eye Irrit. 2; H319: 2% ≤ C < 10%

Harmonised classification- Annex VI of Regulation (EC) No 1272/2008 Included in CLP Regulation, Annex VI (index number 607-001-00-0);

Ammonium sulphamidate Acute Tox. 4 H302 (harmful if

swallowed) 49 Pre-registered Substance



96

Substance Name



Number of Notifiers



(CAS 7773-06-0) (EC 231-871-7)

Not classified - 46

Not included in the CLP Regulation, Annex VI; Included in C&L inventory

Acute Tox. 4 Aquatic Acute 1

H 302 (harmful if swallowed) H 400 (very toxic to aquatic life)

23

Ammonium chloride (CAS 12125-02-9) (EC 235-186-4)

Acute Tox 4 Eye Irrit. 2

H 302 (harmful if swallowed) H 319 (causes serious eye irritation)

Harmonised classification- Annex VI of Regulation (EC) No 1272/2008 Included in CLP Regulation, Annex VI (index number 017-014-00-8);

APPENDIX 2.1.8: ALTERNATIVE 8: Physical vapour deposition

Table 1: Substance ID and physicochemical properties.



Silicon carbide (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid

EC number 206-991-8 Melting point Dissociate at 2,700°C into graphite and silicon


IUPAC name Silicon carbide Vapour pressure -

Molecular formula SiC Water solubility Insoluble <0.1 mg/L


Non flammable -



Tungsten Carbide (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (crystalline)

EC number 235-123-0 Melting point 2,785°C (at 1,013 hPa)


IUPAC name Tungsten Carbide Vapour pressure -

Molecular formula WC Water solubility Slightly soluble (0.1-100 mg/L)


Non flammable -




97


Chemical name and composition Chromium nitride Physical state at 20°C and 101.3

kPa Powder (black)



IUPAC name azanylidynechromium Vapour pressure -

Molecular formula CrN Water solubility Insoluble


- -



Titanium nitride (mono constituent substance)

Physical state at 20°C and 101.3 kPa Solid (brown)



IUPAC name Titanium nitride Vapour pressure -

Molecular formula TiN Water solubility Insoluble in Water


Non flammable -


Substance Name



Number of Notifiers



Silicon carbide (CAS 409-21-2) (EC 206-991-8)

Not classified - 604


Carc. 1B STOT RE 1

H350 (may cause cancer) H372 (causes damage to organs)

50

Skin Irrit. 2 Eye Irrit. 2 STOT SE 3

H315 (causes skin irritation) H319 (causes serious eye irritation) H335 (may cause respiratory irritation)

25

Tungsten carbide (CAS 12070-12-1) (EC 235-123-0)

Not classified 94


Titanium nitride (CAS 25583-20-4 ) (EC 247-117-5)

Not classified 11

Pre-registered substance; Notified Classification and

Flam. Sol. 2 Skin Irrit. 2

H 228 (flammable solid) H 315 (causes skin irritation)

10



98

Substance Name



Number of Notifiers



Eye Irrit. 2 H 319 (causes serious eye irritation)

labelling according to CLP criteria.

Chromium nitride (CAS 24094-93-7) (EC 246-016-3)

Not classified 3

Pre registered substance; Notified Classification and labelling according to CLP criteria.

APPENDIX 2.1.9: ALTERNATIVE 9: General laser coating technology

Table 1: Substance ID and properties for an exemplary tungsten carbide-cobalt coating.



WC-12Co Commercially available product

Physical state at 20°C and 101.3 kPa Solid (grey, odourless)

EC number Multiple components Melting point 3,410°C

CAS number Multiple components Density -

IUPAC Name Multiple components Vapour Pressure -

Molecular Formula Multiple components Water solubility Insoluble in Water

Molecular weight Multiple components Flammability Flash Point

- -




Number of Notifiers



WC-12Co (commercially available product; Multiple component System)

Skin Irrit. 2, Eye Irrit. 2, STOT SE 3, Carc. 2

-

According to suppliers’ SDS, the following hazard statements are given: May cause eye and skin irritation. Contains Material that may cause target organ damage (based on animal data) Possible cancer hazard-contains material which may

Substance is not REACH registered. Hazard information from suppliers’ SDS.



99



Number of Notifiers



cause cancer (based on animal data).



100

APPENDIX 2.2 - PRE-TREATMENTS: MINERAL ACIDS

Table 1: Substance IDs and physicochemical properties are presented (not exhaustive):

Parameter Value Physico-chemical properties Value


Sulphuric acid (mono constituent substance)

Physical state at 20°C and 101.3 kPa Liquid (odourless)

EC number 231-639-5 Melting point 10.4-10.5°C (pure sulphuric acid)

CAS number 7664-93-9 Density 1.83 g/cm3 (20°C, pure sulphuric acid)

IUPAC name Sulphuric acid Vapour pressure 0.49 hPa (20°C)

Molecular formula H2SO4 Water solubility Miscible with water


Non flammable -

Parameter Value Physico-chemical properties Value

Chemical name and composition Iron(II)-sulphate Physical state at 20°C

and 101.3 kPa Solid

EC number 231-753-5 Melting point > 300°C (decomposes)


IUPAC name Iron(2+) sulphate Vapour pressure -

Molecular formula FeSO4 Water solubility Very soluble (>10,000 mg/L)


Non flammable -

Table 2: Hazard classification and labelling overview

Substance Name



Number of Notifiers



Sulphuric acid (CAS 7664-93-9) (EC 231-639-5)

Skin Corr. 1A Met. Corr. 1

H314 (Causes severe skin burns and eye damage) H290 (may be corrosive to metals)

n/a

Specific Concentration limits: Skin Corr. 1A: C ≥ 15%, H314 Skin Irrit. 2: 5% ≤ C < 15%, H315 Eye Irrit. 2: 5% ≤ C < 15%; H319

REACH registered; Included in CLP Regulation, Annex VI (index number 016-020-00-8);

Iron(II) sulphate (CAS 7720-78-7) (EC 231-753-5)

Acute Tox. 4 Skin Irrit. 2 Eye Irrit. 2

H302 (harmful if swallowed) H315 (causes skin irritation)

-

Reach registered substance; Harmonised classification- Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation).



101

Substance Name



Number of Notifiers



H319 (causes serious eye irritation)

(Index number: 026-003-00-7)



102

APPENDIX 2.3 – SOURCES OF INFORMATION

Information on substance identities, physicochemical properties, hazard classification and labelling are based on online data searches. All online sources were accessed between June and September 2014. The main sources are:

1. European Chemicals Agency: http://echa.europa.eu/de/

2. ChemSpider internet site: http://www.chemspider.com

3. Merck SDS: www.merckgroup.com

4. Sigma Aldrich SDS: http://www.sigmaaldrich.com

5. READE internet site: http://www.reade.com

6. Chemie.de internet site: http://www.chemie.de

7. Alfa Aesar SDS: http://www.alfa.com/content/msds/German/14510.pdf

8. Carl Roth SDS: http://www.carlroth.com

9. MAK Collection for Occupational Health and Safety: http://onlinelibrary.wiley.com

10. Chemical Book internet site: http://www.chemicalbook.com

11. Merck SDS: http://www.merck-performance-materials.com

12. Analytyka SDS: http://www.analytyka.com

13. Airgas.com internet site: http://www.airgas.com/msds/001069.pdf

14. Air Liquide internet site: http://encyclopedia.airliquide.com

15. Air Liquide SDS: http://www.airliquide.de

16. Praxair Surface Technology internet site: www.praxairsurfacetechnologies.com

17. Sciencelab internet site: www.sciencelab.com

http://echa.europa.eu/de/

http://www.chemspider.com/

http://www.merckgroup.com/

http://www.sigmaaldrich.com/

http://www.reade.com/

http://www.chemie.de/

http://www.alfa.com/content/msds/German/14510.pdf

http://www.carlroth.com/

http://onlinelibrary.wiley.com/

http://www.chemicalbook.com/

http://www.merck-performance-materials.com/merck-ppf/detailRequest?unit=CHEM&owner=MDA&productNo=102487&language=DE&country=DE&docType=MSD&source=GDS&docId=/mda/chemicals/msds/de-DE/102487_SDS_DE_DE.PDF

http://www.analytyka.com/

http://www.airgas.com/msds/001069.pdf%204

http://www.airgas.com/msds/001069.pdf%204

http://encyclopedia.airliquide.com/

http://www.airliquide.de/

http://www.praxairsurfacetechnologies.com/

http://www.sciencelab.com/



103

APPENDIX 3 – MTT 18

Qualitätssicherungsnorm / Quality Assurance Standard ccccc

MTT 18 Ausgabe / Issue 2014-03

Translation remark This specification provides a translated (equivalent) version in English; any perceived discrepancy or dispute as to the intent of the

English version shall be resolved by reference to the original German version. MTU Aero Engines will not accept any liability for damage resulting from any errors in the translation.

Fortsetzung Seite 2 bis 11 Continued on pages 2 to 11

Bearbeitet/Prepared

TAFC – Schünke

Geprüft/Checked

TAFC – Dr. Niegl

MTU Aero Engines AG Für diese Werknorm behalten wir uns alle Rechte vor.

All rights reserved for this company standard.

Ersatz für Ausgabe 2010-03 Supersedes 2010-03 issue

Freigabeverfahren für Hilfs-, Betriebs-, Zusatzwerkstoffe und Gefahrstoffe

Procedure for the approval of auxiliary materials, operating materials, filler materials and hazardous materials

Inhalt Seite

1 Anwendungsbereich ...................................... 2

2 Begriffe ........................................................... 2

3 Produkt- und verwendungsspezifische Unterscheidungen .......................................... 4

4 Ablauf und Zuständigkeiten ........................... 6

5 Regelung für Experimentalstoffe und Laborchemikalien ........................................... 8

6 Dokumentation und Endverbleibserklärung ... 9

7 Zulassungsbeschränkungen ........................ 10

Contents Page

1 Scope ............................................................. 2

2 Terms and definitions ..................................... 2

3 Distinctions to be made depending on the product and use ............................................. 4

4 Procedure and competences ......................... 6

5 Provisions for experimental materials and laboratory chemicals ...................................... 8

6 Documentation and end use certificates ........ 9

7 Restrictions on approval ............................... 10

MTT 18 Seite / Page 2 Ausgabe / Issue 2014-03

1 Anwendungsbereich

1 Scope

Die Norm gilt für den Standort München der MTU Aero Engines und den Standort MTU Rzeszow ; sie enthält Zuständigkeiten und Regeln für die Prüfung, Beschaffung und Genehmigung, der Verwendung von Hilfs-, Betriebs-, Zusatzwerkstoffen und Gefahrstoffen für definierte Anwendungen in Entwicklungs-, Fertigungs-, Instandsetzungs- und Instandhaltungsprozessen.

Die vorliegende Norm gilt für

Hilfs- und Betriebsstoffe, bei welchen eines oder mehrere der im folgenden genannten Kriterien zutreffen oder nicht mit Sicherheit ausgeschlossen werden können:

o mittelbare oder unmittelbare Beeinflussung

von Produkten für Luftfahrtgeräte

o Berührung oder Kontaminierung von

Produkten für Luftfahrtgerät

o Verwendung zur Herstellung, Montage, Instandhaltung und Wartung von Produkten für Luftfahrtgerät

Zusatzwerkstoffe, welche an Produkten für Luftfahrtgerät verbleiben. Im Regelfall sind dies Werkstoffe für Löt- und Schweißverbindungen sowie für Beschichtungen.

Experimentalstoffe

Gefahrstoffe, die nicht an Triebwerken oder Triebwerksteilen angewendet werden

Hilfs-, Betriebs-, Zusatzwerkstoffe und Gefahrstoffe, die in den Anwendungsbereich dieser Norm fallen, bedürfen grundsätzlich der im Folgenden beschriebenen Verfahrensweise zur Freigabe.

This standard shall be observed at MTU Aero Engines at the company’s Munich location and the Rzeszow location; it details the competences and contains provisions for the inspection, the procurement and approval, and the use of auxiliary materials, operating materials, filler materials, and hazardous materials for specific applications in development, production, repair and maintenance processes.

This standard applies to

auxiliary materials and operating materials to which one or several of the criteria listed below applies (apply), or for which it cannot definitely be ruled out that criteria apply:

o any direct or indirect effects on products for

aeronautical equipment

o contact with or contamination of products for

aeronautical equipment

o use for the production, assembly, maintenance and overhaul of aeronautical equipment

Filler materials that will remain on products for aeronautical equipment. As a rule, this applies to materials used for brazing, for welding, and for coating.

Experimental materials

Hazardous materials not used on engines or engine.

Auxiliary materials, operating materials, filler materials, and hazardous materials covered by the scope of this standard are invariably subject to the approval procedure described hereinafter.

Darüber hinaus haben Prozessbevollmächtigte nach MTT 430-1 die Möglichkeit, für Stoffe die für den jeweiligen Prozess qualitätsrelevant sind, ebenfalls ein Zulassungsverfahren entsprechend dieser Norm zu veranlassen (z.B. Erodierdrähte, Schweisszusätze etc.).

Moreover, where materials have an impact on the quality of the respective special process, the designated process specialists according to MTT 430-1 may elect to have such materials subjected to an approval process according to this standard (e.g. EDM wire, welding fillers, etc.).

2 Begriffe 2 Terms and definitions

2.1 Hilfsstoffe 2.1 Auxiliary materials Hilfsstoffe im Sinne dieser Norm sind Hilfsmittel für spezielle Fertigungs- und Prüfverfahren. Sie sind nicht unmittelbarer Bestandteil von Fertigteilen oder Baugruppen. Daher lassen sie sich am fertigen Teil nicht nachweisen bzw. kommen nur in chemisch veränderter Form vor, z. B. Reinigungsmittel, Härtesalze.

The term "auxiliary materials" as used within the context of this standard shall denote production resources used for special manufacturing and inspection processes. They do not form a direct constituent of finished parts or assemblies. Therefore, they are no longer present, and hence verifiable, on the finished part or exist only in chemically modified form, e.g. cleaning agents, hardening salts.


2.2 Betriebsstoffe 2.2 Operating materials Betriebsstoffe im Sinne dieser Norm sind Stoffe, die den Luftfahrtgeräten für den laufenden Einsatz zugeführt werden müssen und die im Regelfall im Rahmen der üblichen Wartung der Luftfahrtgeräte ergänzt oder erneuert werden, z. B. Kraft- und Schmierstoffe. Weiterhin sind Betriebsstoffe Materialien, die zur Durchführung bzw. Aufrechterhaltung des Produktionsprozesses benötigt werden.

The term "operating materials" as used within the context of this standard shall denote materials that must be added to aeronautical equipment to maintain its proper operation and that are usually replenished or replaced as part of the regular overhaul of the aeronautical equipment, e.g. fuels and lubricants. Moreover, operating materials include materials needed in production processes or needed to maintain production processes.

2.3 Zusatzwerkstoffe 2.3 Filler materials Zusatzwerkstoffe im Sinne dieser Norm sind Materialien, die bei der Herstellung von Erzeugnissen neben den Fertigungsmaterialien ergänzend verarbeitet werden und so in bleibender und nachweisbarer Form Bestandteil von Teilen oder Baugruppen sind (Beispiel: Anstrichstoffe, Kleber, Dichtmittel, Spritzwerkstoffe, Schweißdrähte).

The term "filler materials" as used within the context of this standard shall denote materials that are used during the manufacture of products in addition to the production materials proper; they become a constituent part of the parts or assemblies and can be verified on them (as, for instance, paints, adhesives, sealants, spraying materials, welding wire).

2.4 Experimentalstoffe 2.4 Experimental materials Experimentalstoffe im Sinne dieser Norm sind Hilfs- und Betriebsstoffe sowie Zusatzwerkstoffe die für Versuche benötigt werden und deren Verwendung für Entwicklungs- und Serienteile sowie für Prozesse zur Herstellung und Prüfung von Entwicklungs- und Serienteilen zuverlässig ausgeschlossen wird.

The term "experimental materials" as used within the context of this standard shall denote auxiliary and operating materials as well as filler materials that are needed for tests and for which reliable measures are in place to preclude their use on development and production parts as well as their use in production and inspection processes for development and production parts.

2.5 Gefahrstoffe 2.5 Hazardous materials Gefahrstoffe sind gefährliche Stoffe oder gefährliche Zubereitungen im Sinne §3a des Chemikaliengesetzes, die eine oder mehrere der dort aufgeführten Eigenschaften aufweisen.

Hazardous materials are dangerous substances or dangerous preparations within the meaning of Section 3a of the Gefahrstoffverordnung (German Toxic Substances Control Act (commonly referred to as the "Chemicals Act")that exhibit one or several of the properties listed in that section.

2.6 Laborchemikalien 2.6 Laboratory chemicals Laborchemikalien sind Stoffe, die zur Ausführung der geforderten Tätigkeiten in einem Verfahrenslabor, oder chemischen Labor notwendig sind. Diese Laborchemikalien sind von der zuständigen Fachabteilungen in einer Liste zu dokumentieren. Diese Liste ist zu aktualisieren.

Laboratory chemicals are substances a process laboratory or chemical laboratory needs to work with to carry out the activities it is required to perform. A list of these laboratory chemicals shall be maintained and kept up to date by the specialist departments in charge.


3 Produkt- und verwendungsspezifische Unterscheidungen

3 Distinctions to be made depending on the product and use

Bei der Freigabe von Hilfs-, Betriebs-, Zusatzwerkstoffen und Gefahrstoffen wird das Freigabeverfahren für die im Folgenden aufgelisteten Gruppen unterschiedlich gehandhabt.

The process followed in the approval of auxiliary materials, operating materials, filler materials, and hazardous materials varies for the groups listed below.

3.1 Vom Triebwerkshersteller zugelassene

Hilfs- und Betriebsstoffe sowie Zusatzwerkstoffe

3.1 Auxiliary materials and operating materials as well as filler materials approved by the engine manufacturer

Dies betrifft Hilfs-, Betriebs-, Zusatzwerkstoffe und Gefahrstoffe, welche jedes der folgenden Kriterien erfüllen:

vom Triebwerkshersteller (Type certificate holder) zugelassen,

durch eine Norm des Triebwerksherstellers eindeutig definiert,

im Service Manual des entsprechenden Triebwerksherstellers vorgeschrieben,

nicht durch eine MTU-interne Norm detaillierter beschrieben sind.

Typische Beispiele hierfür sind Lot- und Schweißzusatzwerkstoffe.

Any auxiliary material, operating material, filler material, and hazardous material that meets each of the following criteria:

It is approved by the engine manufacturer (type certificate holder).

It is clearly specified in a standard issued by the engine manufacturer.

Its use is specified in the Service Manual of the respective engine manufacturer.

It is not specified in more detail in an MTU company standard.

Typical examples are brazing fillers and welding fillers.

Dies gilt, soweit das europäischen Chemikalienrecht die Verwendung dieser Stoffe/Produkte uneinge-schränkt zulässt.

This shall apply to the extent the European legislation on chemicals permits the use of these materials/substances/products without restrictions.

3.2 Experimentalstoffe und Laborchemikalien 3.2 Experimental materials and laboratory

chemicals Die Regelung für Experimentalstoffe gemäß Abschnitt 5 betrifft Hilfs- und Betriebs-, Zusatzwerkstoffe und Gefahrstoffe, die einmalig für Grundsatzuntersuchungen, etc. benötigt werden und deren Verwendung für Entwicklungs- und Serienteile sowie für Prozesse zur Herstellung und Prüfung von Entwicklungs- und Serienteilen zuverlässig ausgeschlossen wird.

The provisions for experimental materials as per clause 5 shall apply to auxiliary materials and operating materials, filler materials and hazardous materials that are required only once for basic examinations, etc. and for which reliable precautions are in place to preclude their use on development and production parts as well as their use in production and inspection processes for development and production parts.

Diese Regelung darf nur in Organisationseinheiten zur Anwendung gelangen, bei denen ein ausreichendes Fachwissen über Handhabung und Gefahrenpotential beim Personal vorhanden ist. Im Regelfall sind dies Werkstofflabor, Verfahrenslabor, chemische Labors, Metallografie, etc.

These provisions may be applied only by company functions the staff of which possess sufficient technical know-how on the handling and the potential risk exposure, i.e. usually the materials laboratory, processes laboratory, the chemical laboratories, the metallographic laboratory, etc.

In diese Untersuchungen ist immer der verant-wortliche Prozessbevollmächtigte (PB) einzu-binden. Die Beschaffung solcher Stoffe/Produkte ist durch den PB freizugeben.

The designated process specialist (PB) responsible for the process concerned shall invariably be called in to witness the examinations. Procurement of such materials/substances/products is subject to approval by the PB.

Organisationseinheiten in denen eine Serien-produktion o. ä. stattfindet, sind von dieser Rege-lung grundsätzlich ausgeschlossen. Für Labor-chemikalien gilt diese Regelung zeitlich uneingeschränkt.

As a matter of principle, these provisions must never be applied by company functions in which production takes place. For laboratory chemicals, the provisions apply without there being any time constraint.


Die Vorgehensweise ist in den Prozessdatenblättern IPM-03-04-10-06-02 (Experimentalstoff freigeben) und IPM-03-04-10-06-03 (Laborchemikalie freigeben) beschrieben.

The procedure to follow is described in process data sheets IPM-03-04-10-06-02 (Approve experimental materials) and IPM-03-04-10-06-03 (Approve laboratory chemicals).

3.3 Stoffe für die Produkterstellung und

Instandsetzung nach MTU-Normen 3.3 Materials used for production and

maintenance work performed as per MTU standards

Produkte die sich dieser Gruppe zuordnen lassen und Produkte welche sich keiner der unter Abschnitt 3.1 und Abschnitt 3.2 beschriebenen Produkte zuordnen lassen, bedürfen des kompletten Zulassungsverfahrens. Dies gilt insbesondere auch für die Verwendung neuer Hilfs- und Betriebsstoffe sowie Zusatzwerkstoffe.

Products that fall into this group and products that do not fall into either of the groups described in clause 3.1 and clause 3.2 must be subjected to the complete approval process. This specifically also applies with regard to the use of new auxiliary materials and operating materials as well as filler materials.

Die Vorgehensweise ist in dem Prozessdatenblatt IPM-03-04-10-06-01 (Hilfs-, Betriebs-, Zusatz-werkstoffe und Gefahrstoffe für Fertigung und Instandsetzung bzw. chemische Lösungen freigeben) beschrieben.

The procedure to follow is described in process data sheet IPM-03-04-10-06-01 (Approve auxiliary materials, operating materials, filler materials and hazardous materials for production and repair and/or chemical solutions).

ANMERKUNG Für Gefahrstoffe, die nicht an Triebwerken oder Triebwerksteilen angewendet werden, ist die Erstellung einer Materialnummer (Typ 21 A…..) oder die Erstellung einer Norm (Typ MTS 6xxx) erforderlich (z.B. Farben/Lacke, nicht zur Anwendung am Produkt). Diese Stoffe sind nicht prüfpflichtig.

NOTE: For hazardous materials not used on engines or engine components, it is necessary to have a material number assigned (21 A… type) or a standard prepared (MTS 6xxx type) (e.g. paints not used on the product proper). These materials are not subject to review.

3.4 Stoffe, für deren endgültigen

Fertigungseinsatz eine Langzeiterprobung erforderlich ist

3.4 Materials to be subjected to long-term testing before they may be used in production

Diese Stoffgruppe sind Kühlschmierstoffe und Öle. Um über den endgültigen Einsatz dieser Stoffe eine Aussage machen zu können, ist eine Langzeiterprobung (maximal 6 Monate) notwendig. Für die Durchführung dieser Erprobung muss vor dem Beginn die Begutachtung nach MTT 18 des Stoffes von der “Organisationseinheit “Umwelt-schutz / Arbeitssicherheit “ und “Gesundheits-management“ und die Zustimmung des entsprechenden Prozessbevollmächtigten vorliegen.

This group of materials includes coolant/lubricants and oils. To be able to finally decide whether or not these materials may be used in production, they need to be subjected to long-term testing (for a period of up to 6 months). Prior to commencing the tests, the material shall have been reviewed by the environment and health and safety engineering and the health management specialist departments as specified in MTT 18, and approval must have been obtained from the designated process specialist in charge.

Ist das Produkt erfolgreich erprobt, erfolgt die weitere Freigabe nach MTT 18. Ist das Produkt für den weiteren Einsatz nicht freigegeben, so muss der Anwender schriftlich den Nachweis erbringen, dass das Produkt fach– und sachgerecht entsorgt wurde. Die Dokumentation ist über den versuchsaus-führenden Bereich der Fachabteilung Verfahrens-entwicklung sicherzustellen.

Once the material has been tested with a satisfactory result, the requirements specified in MTT 18 shall be followed for further approval. If the product is not released for use, the user is required to provide, in writing, objective evidence that the product has been properly disposed of. The documentation shall be forwarded to the Surface Technology Chemical and mechanical Practices department.

Der oben genannte Ablauf gilt nicht für Stoffe mit giftigen, krebserzeugenden, fruchtschädigenden oder fortpflanzungsgefährdenden Eigenschaften (T+: T oder CMR) nach der der Gefahrstoff-verordnung.

The procedure described above shall not apply with regard to materials with properties that are toxic, cancinogenic, teratogenic or toxic to reproduction (T+: T or CMR) as per the German Toxic Substances Control Act.

Für Bettbahnöle etc. sind die Betriebsstoffnormen Stoffnormen des Typs MTS 6xxx zu erstellen.

For slideway oils and the like, materials specifications of the MTS 6xxx type shall be prepared.


3.5 Chemische Lösungen für die Produkterstellung und Instandsetzung nach MTU-Normen

3.5 Chemical solutions for production and repair in accordance with MTU standards / specifications

Bei diesen chemische Lösungen handelt es sich um Gemische. Im Sinne dieser Norm bestehen Gemische aus mindestens zwei chemischen Lösungen mit unterschiedlichen zugelassenen Sachnummern/ Materialnummer. Diese chemischen Lösungen, bedürfen eines verkürzten Zulassungsverfahrens. Die dafür notwendigen rechtskonformen Sicherheitsdaten-blätter werden von der Abteilung Metallografie und chemisch und physikalisch Analytik erzeugt und beigestellt.

These chemical solutions are mixtures. The term “mixture” as used herein shall denote the physical blend of at least two chemical solutions assigned different approved item numbers/part numbers. These chemical solutions require an abbreviated approval process. The legally compliant material safety data sheets required to support abbreviated approval are generated and made available by the metallography and chemical /physical analysis department.

Die Vorgehensweise ist in dem Prozessdatenblatt IPM-03-04-10-06-01 (Hilfs-, Betriebs-, Zusatzwerk-stoffe und Gefahrstoffe für Fertigung und Instand-setzung bzw. chemische Lösungen freigeben) beschrieben.


3.6 Stoffe für die Instandsetzung und/oder

Neuteilfertigung am Standort Rzeszow 3.6 Material for part repair and/or production at

the location Rzeszow Produkte die sich dieser Gruppe zuordnen lassen und an keinem anderen Standort verwendet werden, bedürfen des kompletten Zulassungs-verfahrens. Die Vorgehensweise ist in dem Prozessdatenblatt („Release of Auxilliary, operating and filler material or rather chemical dilutions“ ) nach IPR-03-04-24 beschrieben. Produkte die an anderen Standorten bereits eingesetzt werden, bedürfen einer Bewertung der Abteilung Arbeits- und Umweltschutz.

Products that fall in to this group and they are not used at other locations must be subjected to the complete approval process. The procedure to follow is described in process data sheet IPR-03-04-24 (Release of Auxilliary, operating and filler material or rather chemical dilutions). Products that are used at other locations must be subjected of the Health and Safety and Environmental Protection Department.

4 Ablauf und Zuständigkeiten 4 Procedure and competences

Der Ablauf und die Zuständigkeit sind in folgenden IPM geregelt.

The procedure and the competences are regulated in the following IPMs.

IPM-03-04-10-06-02 Experimentalstoff freigeben IPM-03-04-10-06-03 Laborchemikalie freigeben

IPM-03-04-10-06-02 Approve experimental materials IPM-03-04-10-06-03 Approve laboratory chemicals

IPM-03-04-10-06-01 Hilfs-, Betriebs-, Zusatzwerkstoffe und Gefahrstoffe für Fertigung und Instandsetzung bzw. chemische Lösungen freigeben

IPM-03-04-10-06-01 Approve auxiliary materials, operating

materials, filler materials and hazardous materials for production and repair and/or chemical solutions

IPM-03-04-10-06 Gefahrstoffmanagement für Hilfs-, Betriebs-, Zusatzwerkstoffe durch- führen

IPM-03-04-10-06 Perform hazardous substances management

for auxiliary materials, operating materials, filler materials

IPR-03-04-24 Release of Auxilliary, operating and filler material or rather chemical dilutions

IPR-03-04-24 Release of auxiliary, operating and filler

materials or other chemical solutions


4.1 Detaillierung Abläufe, Zuständigkeiten 4.1 Procedures in detail, competences 4.1.1 Feststellung der Stoffgruppe 4.1.1 Determination of the material group Der Antragsteller prüft ob es sich bei dem Hilfs-, Betriebs-, Zusatzwerkstoff und Gefahrstoff um einen bereits von Triebwerksherstellern zugelassenen Stoff oder um einen Experimentalstoff handelt. Für Experimentalstoffe gelten die Regelungen gemäß Abschnitt 5. Für alle sonstigen Stoffe gilt der vollständige Ablauf gemäß Abschnitt 4. Handelt es ich um einen bereits durch einen Triebwerkshersteller zugelassenen Stoff, ist vom Antragssteller die schriftliche Zustimmung des entsprechenden Prozessbevollmächtigten einzuholen (MTT 430-1).

The applicant shall check whether the auxiliary material, operating material, filler material, or hazardous material is one already approved by any engine manufacturer(s) or whether it is an experimental material. For experimental materials, the provisions detailed in clause 5 shall apply. For all other materials, the complete procedure as per clause 4 shall be followed. If the material has already been approved by an engine manufacturer, the applicant shall obtain the written approval from the designated process specialist in charge (MTT 430-1).

4.1.2 Antragstellung 4.1.2 Filing of a request Zusatzwerkstoffe und Gefahrstoffe die nicht Hilfs-, Betriebs bereits von einem Triebwerkshersteller zugelassen sind bzw. nicht der Gruppe der Experimentalstoffe und Laborchemikalien zuordenbar sind, bedürfen grundsätzlich eines kompletten Freigabe-Durchlaufes gemäß vorliegender Norm. Bei neuen, bisher nicht verwendeten Hilfs-, Betriebs-, Zusatzwerkstoffen und Gefahrstoffen füllt der Bedarfsträger die entsprechenden Formblätter ( MTT18BBL1) aus und leitet das Freigabeverfahren ein. Die Beschaffung der Produkte ohne Verwendung von Materialnummern und material-stammgebundener Bestellung ist generell nicht zulässig.

Auxiliary materials, operating materials, filler materials, or hazardous materials that are not yet approved by an engine manufacturer and do not fall into the experimental material or laboratory chemical group shall invariably be subjected to the complete approval process described herein. For any new, not previously used auxiliary materials, operating materials, filler materials, or hazardous materials, the requisitioner shall complete the appropriate forms (MTT18BBL1) and shall initiate the approval process. Procurement of any products is generally not permissible unless part numbers are used and the purchase order is based on material master data.

4.1.3 Sicherstellung der ordnungsgemäßen

Handhabung 4.1.3 Safe handling practices

Handelt es sich bei dem neu zu beschaffenden Stoff um einen Gefahrstoff, so ist sicherzustellen, dass für den innerbetrieblichen Umgang mit diesem Gefahrstoffen eine Betriebsanweisung existiert, welche eine Gefährdung von Personen ausschließt, die erforderlichen Schutzmaßnahmen beschreibt und mindestens folgende Punkte umfasst:

Hinweis auf die Gefahren für Mensch und Umwelt

Festlegung der Schutzmaßnahmen und Verhaltensregeln

Hinweise auf Verhalten im Gefahrenfall und Maßnahmen zur Ersten Hilfe

Festlegungen zur Entsorgung

If the new material to be procured is a hazardous material, care shall be taken to ensure that operating instructions for the safe handling of that material on company premises exist; these shall prevent any hazards to humans, describe the necessary precautions, and comprise at least the following:

Information on the hazards to humans and the environment

Stipulations on the precautions to take and rules of conduct

Information on the safe response in the event of an emergency, and first-aid measures

Stipulations on proper, safe disposal


Erst nach Erstellung der Betriebsanweisung dürfen Hilfs-, Betriebs-, Zusatzwerkstoffe und Gefahrstoffe für den vorgesehenen Zweck eingesetzt werden. Eine Auflistung aller zugelassenen Gefahrstoffe und die zugehörigen Betriebsanweisungen („MTU-Stoffliste“) wird von der Organisationseinheit “Umweltschutz/Arbeitssicherheit“ gepflegt und ist über das Teamcenter (TC) zugänglich.

Only after the operating instructions have been prepared is it permissible to use the auxiliary materials, operating materials, filler materials, and hazardous materials for the intended purpose. A list of all approved hazardous materials along with the pertinent operating instructions ("MTU-Stoffliste", MTU List of Controlled Substances) is maintained by the environment and health and safety engineering company function, which is available to all employees through the company intranet (TC).

4.1.4 Durchführung der

anwendungsspezifischen Untersuchungen 4.1.4 Application-specific reviews

Für die Erprobung der Stoffe ist die freigebende Organisationseinheit (siehe Beiblatt 1 zu MTT 18) zuständig. Diese beurteilt als Fachabteilungen die Eignung des Stoffes für den geplanten und beantragten Einsatz. Ihr obliegt auch die nachträgliche Bewertung / Freigabe / Einschränkung des Einsatzes bereits vorhandener Stoffe und deren Anwendung. Die zuständige Organisationseinheit prüft, initiiert und überwacht die für eine Freigabebeurteilung notwendige Anwendererprobung. Ihr obliegt auch die nachträgliche Bewertung / Freigabe / Einschränkung des Einsatzes bereits vorhandener Stoffe und deren Anwendung

The approving company function (see Beiblatt 1 zu MTT 18) shall be responsible for testing the materials. It is the specialist department that tests the material for its suitability for the envisaged use for which the request was filed. It is likewise responsible for the subsequent evaluation, approval or restriction of the use of existing materials and their application. The company function in charge shall review, initiate and monitor the user-specific tests necessary for evaluating materials for approval purposes. It is likewise responsible for the subsequent evaluation, approval or restriction of the use of existing materials and their application.

Bestehen gegen den Stoff oder dessen vorgesehenen Einsatz Bedenken, sucht die zuständige Organisationseinheit gemeinsam mit dem Anwender eine Alternativlösung. Bei Ablehnung von Stoffen ist die Rückgabe der Proben bzw. eine ordnungsgemäße Entsorgung im Hause zu veranlassen und sicherzustellen.

Whenever there are reservations about the suitability of a material or its intended use, the company function in charge shall get in touch with the user to jointly find an alternative solution. If a material is rejected, care shall be taken to make sure the samples are returned and/or are properly disposed of in accordance with company rules.

5 Regelung für Experimentalstoffe und Laborchemikalien

5 Provisions for experimental materials and laboratory chemicals

(nur anwendbar für den Standort München) (only applicable at the location Munich) Es bestehen grundsätzliche Vorgaben gemäß Abschnitt 4.1 für die Prüfung und Bewertung von Hilfs- und Betriebsstoffen. Bei Experimentalstoffe und Laborchemikalien werden diese Prüfungen und Bewertungen im Rahmen der Beauftragung durch das Fachpersonal der beauftragenden Organisationseinheit durchgeführt.

There are basic specifications in accordance with clause 4.1 for the inspection and evaluation of auxiliary materials and operating materials. With experimental materials and laboratory chemicals, these inspections and assessments shall form part of the ordering process and be performed by the specialist staff of the company function placing the order.

5.1 Bestellung 5.1 Order placement Die für den Einkauf zuständige Organisationseinheit bestellt Experimentalstoffe ausschließlich nur auf Anforderung von Personen aus hierfür zugelassenen Organisationseinheiten. Für diese Bestellungen ist eine Freigabe durch den Prozessbevollmächtigten notwendig. Die Qualitätslenkung veranlasst, dass die Ware mit Sicherheitsdatenblättern und Zertifikaten angeliefert wird.

The company function in charge of purchasing shall place orders for experimental materials only if the request is submitted by an individual from a company function approved to order such materials. Any such purchase orders are subject to approval by the designated process specialist. Quality control shall arrange for the goods supplied to be accompanied by safety data sheets and certificates as necessary.


5.2 Lagerung 5.2 Storage Experimentalstoffe sind getrennt zu lagern und in einer Bestandsliste zu führen. Sie dürfen nicht mit Stoffen, welche bereits freigegeben sind gemeinsam gelagert werden. Die Art der Lagerung muss die Möglichkeit von Verwechslungen mit freigegebenen Stoffen zuverlässig ausschließen.

Experimental materials shall be stored separately, and the associated data shall be entered in an inventory list that is kept up to date. It is not permissible to store them together with materials that have already been approved. The experimental materials shall be stored in a manner that eliminates any possibility of them getting confused with approved materials.

Experimentalstoffe sind mit einem Aufkleber eindeutig zu kennzeichnen (z.B. Aufkleber „Experimentalstoff“ bzw. „Laborchemikalie“).

Experimental materials shall be clearly marked with a label (e.g. "experimental material" or "laboratory chemical" label).

5.3 Versuchsdurchführung 5.3 Testing Werden Entwicklungs- oder Serienteile zu Versuchen mit Experimentalstoffen verwendet, so sind diese Bauteile vor dem Versuch zerstörend zu kennzeichnen, so dass eine potentielle Weiterverwendung zuverlässig ausgeschlossen werden kann.

Where development parts or production parts are used for the testing in which experimental materials are used, the components shall be identified prior to testing, by a destructive method, to prevent their re-use.

5.4 Zulassung von Experimentalstoffen für

Serienanwendung 5.4 Approval of experimental materials for the

production application (nur anwendbar für den Standort München) (only applicable at the location Munich) Sollen Experimentalstoffe nach einer erfolgreichen Erprobung für die Serie verwendet werden, ist das vollständige Freigabeverfahren gemäß Abschnitt 4 durchzuführen.

Where experimental materials that have successfully undergone testing are to be used in production, the complete approval process as per clause 4 shall be performed.

Die Vorgehensweise ist in dem Prozessdatenblatt IPM-03-04-10-06-01 (Hilfs-, Betriebs-, Zusatzwerk-stoffe und Gefahrstoffe für Fertigung und Instand-setzung bzw. chemische Lösungen freigeben) beschrieben.


6 Dokumentation und Endverbleibs- erklärung

6 Documentation and end use certificates

(nur anwendbar für den Standort München) (only applicable at the location Munich) Die Prüfungen auf Umweltverträglichkeit, Gesund-heitsgefährdung und Einhaltung der gesetzlichen Vorgaben sowie die Vorgaben für Beschaffung und Handhabung sind zu dokumentieren.

Documentation shall be maintained on the reviews for environmental compatibility, health hazards and compliance with legal requirements, and on the requirements applicable to the procurement and handling.

Dazu wird das gesamte Zulassungspaket im Teamcenter (TC) abgelegt. Die Dokumentation der Betriebsanweisungen erfolgt im Teamcenter (TC).

For the purpose, the entire approval package shall be stored in the Teamcenter (TC) document management system.

Auf Anfrage von Lieferanten erstellt die MTU für bestimmte Stoffe sog. Endverbleibserklärungen (stellt die zweckgebundene Verwendung gefährlicher Chemikalien sicher).

Upon an enquiry coming in from a supplier, MTU shall issue so-called "end use certificates" for a number of chemicals (to ensure hazardous chemicals are used solely for the purpose for which they are intended).

Erforderliche Endverbleibserklärungen werden von den Verantwortlichen per Unterschrift gegenüber den Lieferanten gegengezeichnet. Die MTU-Unterschriftenregelung bleibt davon unberührt.

Where end use certificates are required, they are countersigned by the individuals in charge to confirm the end use vis-à-vis the supplier. MTU's rules regarding authorization to sign company documents shall remain unaffected by this provision.


Für Sachverhalte nach dem Grundstoff-überwachungsgesetz wurde der Centerleiter Fertigung benannt; für giftige, hochgiftige Stoffe und galvanotechnisch eingesetzte Chemikalien zeichnet der Leiter Galvanik und für Laborchemikalien zum ausschließlichen Einsatz im Laborbereich, der Leiter Analytik (Laborleiter). Für Stoffe, die keinem Center zuzuordnen sind, übernimmt diese Aufgabe der Leiter Zulieferqualität und Lieferantenentwicklung.

Matters governed by the shall be the responsibility of company center production ; the head of the electroplating shop shall be responsible for any toxic or highly toxic materials and electroplating chemicals, the head of analytics (laboratory manager) for laboratory chemicals for the exclusive use in the lab area. Responsibility for materials that cannot be related to a specific company center shall be assumed by the head of supplier quality and development.

7 Zulassungsbeschränkungen 7 Restrictions on approval

Handelt es sich im Zulassungsverfahren um „sehr giftige“, „giftige“, „krebserzeugende“, „fruchtschädigende“ oder „erbgutverändernde“ Stoffe, wird die Einführung durch die Organisationsabteilung “Umweltschutz / Arbeitssicherheit“ zurückgewiesen.

If the materials to be approved are of the "very toxic", "toxic", "carcinogenic", "teratogenic" or "mutagenic" type, the environment and health and safety engineering specialist department will disapprove their introduction.

Erkennbar sind diese Stoffe nach der Kennzeichnung nach GHS/CLP und den Gefahrenhinweisen (H-Sätze):

These materials are identified/labeled as being of the above type with the pictograms as per GHS/CLP and the chemical hazard precautions (hazard statements):

Totenkopf GHS06

H300/H301/H310/H311/H330/H331

Signalwort: Gefahr

Lebensgefahr/giftig beim Verschlucken, Hautkontakt,Einatmen

Gesundheitsgefahr GHS06

H340/H350/H360/H370/H372

Signalwort: Gefahr

Mutagen/cancerogen/reprotoxisch jeweils Kategorie 1A und 1B

Skull and crossbones GHS06

H300/H301/H310/H311/H330/H331

Signal word: Danger

Fatal/toxic if swallowed, in contact with the skin or inhaled

Health hazard GHS06

H340/H350/H360/H370/H372

Signal word: Danger

Mutagenic/cancinogenic/toxic to reproduction, categories 1A and 1B in each case

Stoffe die als besonders besorgniserregend eingestuft (SVHC) und auf der Kandidatenliste der ECHA gelistet sind, werden als Rein- oder Inhaltsstoff eines Produktes zurückgewiesen.

Substances classified to be of very high concern (SVHC) and included in the ECHA candidate list in pure form or in a preparation are rejected.

Der Anwender muss nachweisen, dass die Verwendung eines weniger gefährlichen Stoffes/Produktes nicht möglich ist. Der Nachweis ist über einen Bericht zur Substitution nach Gefahrstoffrecht zu führen. .

The user is to submit proof that the use of an equivalent substitute that is less hazardous is not available for the particular purpose. Proof shall be provided by submitting of a substitution report according to hazardous substances legislation.

Erläuternde Angaben Explanatory notes Änderungen gegenüber Ausgabe 2010-03 sind mit Randbalken gekennzeichnet.

Revisions to 2010-03 are marked by a marginal line.

Abschnitte 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 4, 4.2.2, 5.1, 5.4 5.5, 6 und 7 geändert

Clauses 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 4, 4.2.2, 5.1, 5.5, 6 und 7 changed.

Abschnitte 4.1, 4.2.3 – 4.2.6, 4.2.8, 4.2.10 - 4.2.12 entfernt.

Clauses 4.1, 4.2.3 – 4.2.6 deleted.

Redaktionell überarbeitet. Editorially revised. Zweisprachige Ausgabe. Bilingual version.


Weitere Unterlagen: Associated documents: Beiblatt 1 zu MTT 18 Freigabe von Hilfs- und

Betriebsstoffen, Zusatzwerkstoffen; Zulassungspaket; Ausfüllanweisung und Verfahren

Beiblatt 1 zu MTT 18 Approval of auxiliary and operating materials, filler materials; Approval package; Completion instructions and procedure

MTT 20001-1 Normensystem; Grundlagen MTT 20001-1 Standards system; Fundamentals MTT 20001-4 Normensystem; Stoffnormen;

Werkstoffnormen, Zusatzwerkstoffnormen und Betriebstoffnormen, Hilfsstoffnormen

MTT 20001-4 Standards system; Material standards, materials specifications, filler materials specifications operating material standards, auxiliary materials standards

MTT 430-1 Prozessbevollmächtigte bei MTU

Aero Engines MTT 430-1 Special processes; Designated

process specialists; Roles and responsibilities

MTT 73-7 Qualitätsmanagement

Zulieferungen; Planung der Verifikationsmaßnahmen

MTT 73-7 Quality management – vendor-supplied items; Planning of the verification measures

MTT 73-8 Qualitätsmanagement

Zulieferungen; Bestellangaben und Dokumentenverteilung

MTT 73-8 Quality management – vendor-supplied items; Ordering data and distribution of documents

Chemikaliengesetz

German Toxic Substances Control Act (Chemicals Act)

Gefahrstoffverordnung German Hazardous Materials Ordinance Strahlenschutzverordnung German Radiation Protection Ordinance Verordnung 1907/2006/EG zur Registrierung, Bewertung, Zulassung und Beschränkung von Chemikalien – REACh

Regulation (EC) No 1907/2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH)

Verordnung (EG) Nr. 1272/2008 über die Einstufung, Kennzeichnung und Verpackung von Stoffen und Gemischen – CLP

Regulation (EC) No 1272/2008 on Classification,

Labelling and Packaging of Substances and

Mixtures TRGS 600 Substitution

analysis of alternatives non-confidential report · 2016. 4. 20. · copy right protected –...

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