chromium and cadmium replacement options for advanced … · advantages and limitations advantages...

Keith Legg, [email protected], 847-680-9420

Chromium and Cadmium ReplacementOptions for Advanced Aircraft

Keith LeggHCAT Program Review, KSC, Nov 2003

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1. REPORT DATE NOV 2003 2. REPORT TYPE

3. DATES COVERED 00-00-2003 to 00-00-2003

4. TITLE AND SUBTITLE Chromium and Cadmium Replacement Options for Advanced Aircraft

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6. AUTHOR(S) 5d. PROJECT NUMBER

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7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Rowan Technology Group,1590 S. Milwaukee Ave., Suite 205,Libertyville,IL,60048

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12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited

13. SUPPLEMENTARY NOTES 23rd Replacement of Hard Chrome Plating Program Review Meeting, November 18-19, 2003, CapeCanaveral, FL. Sponsored by SERDP/ESTCP.

14. ABSTRACT

15. SUBJECT TERMS

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as

Report (SAR)

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Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18


Chrome replacement

Keith Legg, [email protected]

Summary of best options

ID>1.5”>0.001” thick

IDs>3” (> 1.5” withnew gun)

Plasma spray

Cost<0.001” thickness

Gun barrel IDs, smallcomponents

PVD

Heat treatIDs, TDC alt., carrierLG?

Nano Co-Pelectroplate

Adhesion, build-up, heat treat

IDs, other NLOS, TDCalt.

Electroless Ni(Ni-P, Ni-B)

>0.001” thickNot IDs

Landing gear,hydraulics, flap tracks

Thermal spray(HVOF)

LimitationsApplicationsTechnology

Qualified In test


Niche options

Ion (Plasma) Nitride500°C vacuum heat treatAdd oxide for corrosion resistance

ElectrocompositesElectroplated Ni or Co with hard particles

Laser claddingWeld surfacing (also laser glazing, LISI, etc.)

Electrospark deposition (alloying)Localized repair and build-up

Explosive claddingWide area bonding – IDs, gun tubes, etc.


Data available

Large quantity of detailed performancedata available from HCAT, including rigand flight tests; also commercial flightexperience


HVOF – available data


Reports available

HCATLanding Gear

Joint Test ReportCost and PerformanceReportFinal Report (NRL report)

Propeller HubsJoint Test ReportCost and PerformanceReportFinal Report (NRL report)

JSF ReportsHVOF as a Cr replacementID Cr alternativesRepair options for Cr and Cd

Original DARPA Cr optionsreport

C-HCAT (Landing Gear folder)Heroux Devtek

Fluid compatibilityGrindingNDIStripping

DNDCoupon testing

Messier-DowtyF-18 landing gear and dragbrace rig tests (availableshortly)

Goodrich (available later)Dash-8 rig testBend tests

Note: C-HCAT is all WC-CoCr


Applications - military

QualifiedLanding gear componentsapproved for HVOF coating atHill AFB

A-10 MLG PistonA-10 NLG PistonB-1 MLG AxleC-130 MLG PistonC-141 MLG Bogie BeamC-141 Outer CylinderC-5 MLG Roll PinC-5 MLG Ball ScrewC-5 MLG Outer PitchF-15 Drive KeysKC-135 MLG Axles

Messier-DowtyCF-18 steering covers, pistonheads, MLG hexagon repair

F-22 (Raptor)F-119 engine, convergent nozzleactuators

Rig and flight testNADEP-CP, H-S, WR-ALC

EA-6B landing gear (flight)P-3 bomb bay door actuators(flight)E-2C, C-2, P-3, and C-130: proptailshaft, low pitch stop leversleeve, rocker land (rig)

LockheedP-3 landing gear (rig)

Messier-DowtyF-18 landing gear (rig)

TF-33 engine, (P&W)Accelerated Mission Test (AMT)

NAVAIR PAX, Greene TweedHydraulic actuator rig tests

F-35 – GoodrichWC-CoCr baselined forpiston and axle journals

F-35 – GoodrichWC-CoCr baselined forpiston and axle journals


Applications - commercial

Commercial – OEMBoeing - >100 spotHVOF usesB767-400 HVOF onlanding gear(production)Airbus 380 spec’d forHVOF WC-CoCr(Goodrich)

GEAE uses for GTE shaftsBombardier flap tracksMessier-Dowty installingHVOF for landing gear

Commercial – MROBoeing permits HVOF forrepair to 0.010”Delta using HVOFlanding gear repair inown maintenance shop

Similar moves at Unitedand American

Flap and slat tracks,various aircraft


Advantages and limitations

AdvantagesMuch better wearresistanceLower seal wear (withproper superfinish)Takes a good finish(superfinish)Little or no fatigue debitDry process, noembrittlementEasily strippedWidely available

LimitationsSpalls at high cyclicbending load (close toyield)Spalls with high point orline loadCoating can corrode(different mechanism)Cannot coat IDsSubstrate heating (mustcontrol process)Must be done in booth(noise and dust, robotic)


Developments needed

More ductile HVOF coatingPrimarily needed for MRO (thick coatings)

Existing material fine for OEM useAvoid spalling at high loadWill almost certainly have worse wear (softer)

But still better than EHCUse only where high bending or contact stressesMay be a layered coating with ductile build and brittleoverlay

Increased wear rate on breakthrough

Same grinding wheel for steel and HVOFIs being done commerciallyHill AFB tests under way – looks readily doable


Summary of HVOF implementation issues

Integrity at high stressIssue only for thick overhaulcoatings on carrier-basedaircraftSensitive to cyclic contactstress

Not seen in rig tests butshould be watched

MaskingCan be very personnel-intensiveCannot use tapesHard masking needed –have to build up maskinventory

GrindingNeed Al2O3 wheel for metalbut diamond wheel forHVOF carbidesMachine resetting ordifferent grindingprocedures (feeds, speeds,lubricants)Recent testing looks good

CorrosionEHC does not corrode –substrate corrodes andundercuts coatingHVOF matrix (Co) cancorrode, causing roughening,leakage, but not undercutting

Slow increases in leakagerather than catastrophicflakingSeen with one operator’sactuators in Europe –probably due to specific fluidsor de-icers used only there

Embrittlement reliefHydrogen appears to diffuseslower through HVOF – mayneed longer H bake afterNital etch


Electroless Ni

Electroless Ni, being a Ni material, is nextagainst the wall and is on the JSF RestrictedMaterials List.Consider as an intermediate coating – a lotbetter than chrome, but likely to needreplacement itself pretty soon.


Applications

Wide variety of industrial applicationsAircraft

GTE components – P&W uses Ni-B various partsCompressor blades (erosion, corrosion)

Shaft rebuildingFlap tracksBearing journals



AdvantagesNo electrodesNo edge build-upThin or thickA variety of ENcomposites available

SiCDiamondTeflon

LimitationsAdhesion always aconcernRequires 300-400°C heattreat for max hardnessHydrogen evolved duringdeposition

Does not seem to causeembrittlement

Bath must be dumpedperiodically


Data available

Like EHC electroless Ni hasbeen around for so long thatlittle data is available

Especially need comparisonto EHC

Some data available fromvendors

Concern over reliability,accuracy

Beware – most data will befor heat treated state, butmost airframe usage will beas-deposited

Wear not as good, corrosionbetter

Studies of a number ofelectroless and electroplatedNi coatings being done byAFRL

Work ongoingTypical hardness 700 – 850HVGood barrier corrosion, butno protection if breached(as with Cr)http://www.materialoptions.com/w2g/cgi/kmcgi.exe?O=DIR0000000H8I&[email protected]


Implementation issues

Reliable adhesion is biggest production issuecited by aerospace usersRequirement for heat treating for maximumhardness means that for many applicationsmust be used as-deposited

Significantly lower wear resistanceData needed for as-deposited and heat treated state


Nanophase Co-P

New coating developed by Integran of Toronto,CanadaSERDP Project #1152, almost completedhttp://www.materialoptions.com/w2g/cgi/kmcgi.exe?O=GRP0000000H8F&V=0


Description

Pulse Plating favorsnucleation of new grains overgrowth of existing grains,resulting in an ultra-fine grainstructure throughout theentire thickness of thecoating, right from thesubstrate interface.

Typical deposition conditions

2ms pulses

125Hz, 25% duty cycle

2 – 3V, 150mA/cm2



AdvantagesDrop-in

Wherever EHC can go Co-P can go

Better corrosion than EHCLittle or no embrittlement

May work for field repair

Looks usable to replaceEHC, TDC, brush Cr

LimitationsESOH

OSHA pel for Co (8hrTWA) = 0.1 mg(Co)/m3

OSHA pel for metallic Cr(8hr TWA) = 1 mg(Cr)/m3

Co not known carcinogenNo regs at this time

Heat treat for besthardnessRequires pulse powersupplies

Capital cost


Data available

Info athttp://www.materialoptions.com/w2g/cgi/kmcgi.exe?O=GRP0000000H8F&V=0


Synthesis of NanocrystallineCo-P Alloys

• Electrodeposition parametersmodified to yield deposits withaverage grain sizes below100nm

• Pulsed Current Deposition• Plating Efficiency >90%• Deposition rate 2-8 mills/hr• Consumable &

nonconsumable anode

Coating Thickness and Integrity of Nano Co 2-3wt%P

Cross-SectionThickness ~135µmNo pits, cracks,pores

Surface MorphologyNodular, cauliflowermorphologyNo pits, cracks,pores

Nano Co-P alloy coatings developed under SERDP project PP-1152 as anenvironmentally-benign replacement for hard Cr coatings for NLOSapplications.

nCo-P structure



ESTCP program approved between HCAT,Lockheed, Curtiss-Wright, Smiths Aero, NADEPJAX, OO-ALC to validate for ID EHC and for TDCreplacement

Will begin January 04Primary issues:

Can it work as a TDC alternative?Heat treat requirements to meet TDC requirementsEmbrittlement – is it really non-embrittling?Long term bath and process stability in depotenvironment (processing many different items)


Physical Vapor Deposition (PVD)

PVD involves deposition from a solidmaterial source – evaporation,sputtering, arc


Applications

Limited applications in aerospaceMajor application is TBCs

E-beam evaporated ZrO2

Wear resistanceTiNBearing races and retainers

Blade erosionMDS Prad coating

FrettingAlCu

Low frictionVariations of MoS2



AdvantagesVery hard, wear resistantReproducible, highqualitySmooth

No finishing neededProbably good TDCalternativeMany vendors

Esp. for TiN, DLC

LimitationsCostThin (typically 3µm –0.0001”)

Cannot be used forrebuild

Lack of specsVacuum requirements

Size limitationsSubstrate temperaturetypically >250°C

Less reliable at low THigh cleanlinessLine of sight


Data available

Large amounts of data available for many PVDcoatings

Most in R&D journalsLittle or no publicly available data for aerospaceproduction use



Best applications for thin wear- or RCF-resistantitems for max life (difficult to strip)

Items that will not be refurbishedPins, gears, bearingsNiche applications

Need data on wear and seal performanceEasy to make components into cutting tools, espwith gearsID hard coatings under development

Marshall Labs, Paradigm Shift Techs


Plasma spray

Plasma spray guns can be small andthe stand-off distance (gun-substrate) ismuch less than with HVOF


Applications

Already specified for various repairs and buildup in GTEs and airframes

Often used for same-material dimensional restoration

In general new applications use HVOF ratherthan plasma spray

Plasma spray cheaper but quality lower

Good method for coating IDsMost guns only capable of coating >3” IDNew Sulzer Metco F-300 gun >1.6”Makes most sense when already use HVOF for OD, socan do ID and OD with same spray booth, robot, etc.


CH-53 helicopter blade damper

Approved for repairT400 plasma spray on IDTypical actuator coatings:

Rod – HVOF/D-gun WC-Co, WC-CoCr, WC-CrNiPiston – HVOF/D-gunWC-Co, T400ID – plasma spray T400

Plasma sprayTribaloy 400(ID, piston)

HVOF/D-gunWC-Co (rod)



AdvantagesSimilar to HVOFAble to coat inside IDsdown to 3” ID for mostguns, 1.6” for Sulzer F-300 gun

LimitationsAdhesion not as good asHVOF

3-7 ksi vs >10 ksi

Lower porosity than HVOF10% vs 1 - 2%Can allow leak-by ingas-over-fluid systems

Requires grind,superfinish

More difficult for ID thanOD


Data available

Nowhere near the amount of data available forHVOF. ID coating data available from HCAT IDplasma spray program.http://www.materialoptions.com/w2g/cgi/kmcgi.exe?O=GRP0000000GOW&V=0



May need to be sealed for some hydraulicapplicationsSurface finish not well defined – likely to needsuperfinishDesign of air sweep to take heat and oversprayfrom IDPlunge-grinding specs for OEM pistons

Coat piston, then plunge-grind seal groove


Conclusions on Cr replacement options

HVOF is the method of choice for most ODsWC-CoCr wherever possible for better corrosion resistanceWhere stress is too high we will need a more ductile coating

Maybe nCo-P, electro- or electroless Ni, or similar, trading wearlife for coating integrity

For IDs standard HVOF not viableElectro- and electroless plating

Widest applications, including thin dense and flash Crreplacement

ID plasma sprayMost cost-effective when using HVOF or other thermal spray forOD

PVDNiche applications because of cost and complexity

Could be broadened with reliable vendors, data, specs,especially for TDC replacement


Cadmium replacement options


Usage

Steel ComponentsThe “cure-all”corrosion coatingGood salt spray andscribed corrosionprotectionNo hydrogenembrittlement orstress corrosioncrackingODs and IDsPlate steel to protectAl

FastenersCorrect lubricity(avoid changes totorque-tensionspecs)No hydrogenembrittlementRetain threadprofile

ConnectorsFor electricalequipmentLow contactresistanceNon-insulatingcorrosion productsSolderable a plus


Galvanic series

•Al and Al alloys•Zn-Ni•Al-Mn•Zn•Be!!

Mother Nature leftus short on options!


Summary of Cd alternative options

Cd alternatives

Aqueouselectroplated

alloysNiche alternatives

Vacuum Alalternatives

Alternative basealloys

IVD aluminum(Ivadizing)

ID sputtered Alfor IDs

Electroplated Al(Alumiplate)

Molten salt bathAl-Mn

Zn-Ni

Sn-Zn

SermeTelceramic coatings

CVD Al (smallIDs)

Non-aqueouselectroplates

Metal-filledpolymers

New highstrength stainless

Al is the only “global” replacementAlmost everything needs chromate conversion

In use In test In development


JSF Cd Alternatives Report

RequirementsAlternatives

Zn-Ni, Sn-ZnelectroplatesAlumiplateAl-Mn molten salt bathIVD and CVD AlSputtered AlThermal spraySermeTelsFilled polymersHigh strength stainlesssteelhttp://www.materialoptions.com/w2

g/cgi/kmcgi.exe?O=DIR0000000GK9&V=0


Joint Test Report

Cd alternatives report forlow strength steels (<220ksi)

Boeing, JGPPSn-ZnAcid Zn-Ni (Boeing)Alkaline Zn-NiIVD Al

http://www.jgpp.com/projects/cadmium/jtr.htmlhttp://www.materialoptions.com/w2g/cgi/kmcgi.exe?O=DIR0000000I6D&V=0


IVD Al

Vacuum PVD processFully qualified and quite widely used by OEMsand depotsSpec MIL-C-83488 for Al coating does not definedeposition method


Applications

MilitaryF-4F-14F-15F-16F-18AV-8BA-12V-22Apache

CommercialBoeing 737, 747, 757,767McDonnell-Douglas DC9,10, MD-80, 90, 11Bombardier Dash 7, 8Airbus A300, A310



AdvantagesQualified commercialprocess

Commercial coating shopsIVD-coated fastenersavailable commercially

Clean and safeGood performanceNo H embrittlement

LimitationsVacuum process

ExpensiveAwkward

Poor quality coating as-deposited

Peen and chromate

Poor throwing powerSoft and easily damaged

Cannot easily be repaired

Dissolves in alkalinecleaners

MRO users may have tochange cleaning process


Data available

Data available from Boeing, JGPP reporthttp://www.jgpp.com/projects/cadmium/jtr.htmlhttp://www.materialoptions.com/w2g/cgi/kmcgi

.exe?O=DIR0000000I6D&V=0


PVD Al for IDs – sputtered Al

Marshall Labs Plug and CoatWorks inside IVD chamber

Makes it possible to coat ODand ID simultaneously Plug& Coat

Add-on to existing IVDchamber

StatusBeing installed at Hill AFBCommercially available Meets MIL Spec.

Note: All Al coatings requireuse of proper aqueouscleaners (avoid alkalinecleaners)


Developments needed

Some additional environmental embrittlementdata neededPlug and Coat miniaturization needed forsmaller IDs

Under way at Marshall Labs

Porosity and need for peening always an issueVarious approaches for better coating quality

Higher plasma densitySputtering instead of IVDPulse biasing


Electroplated Al (Alumiplate™)

Alumiplate, MinneapolisDeposited from organic solution


Alumiplate description

Organic electroplateRequires enclosed tank and plating line ininert environment

Similar to vacuum processing but lessAl salts in toluene solutionReasonable throwing power

Needs conformal or secondary electrodes forcomplex shapes, IDs

Frequently uses Ni strike for adhesionRecent development uses grit blasting andactivation with no Ni strike

Equivalent adhesionMetallic strike needed for insulators such ascompositesCoating thickness 0.0001 – 0.001”

Usually 0.0003 – 0.0005”Conversion coat (traditionally chromate) forbest corrosion performance (as with allother Cd alternative)



Advantages“Drop-in” replacementAble to coat complex shapesHigher quality coating thanas-deposited IVD ALSuitable for components,connectors, fasteners (withdry lube)Directly compatible with AlskinsCan be anodized for betterwear and abrasion

LimitationsSize limited

Landing gear about 3’ longLimited by current bath sizeAppears scalable

Requires dry lube forthreads to prevent gallingSole source is Alumiplate,Minneapolis

Willing to license, but nocurrent licenseesNot yet available in Europe

High capital costToluene bath not suitable forDoD depot useCannot brush plate Al repair

Can brush plate Sn-Zn torepair Al


Data available

A great deal of data becomingavailable as a result of ongoing JSF andArmy testing. Rowan is currentlyputting together a report on thetechnology – available by year’s end


Electrical connectors

Meets all tests for qualification on connectorshells (MIL-DTL-38999K testing)

Al and C-fiber/PEEK compositeCorrosion, conductivity stability in salt fogMate/unmate testing (wear, torque, conductivity)No insulating corrosion products

Amphenol has now assigned part numbers forcommonly-used AlumiPlated aerospaceconnectors


Other issues

RepairabilityAl can be repaired by brush plating Sn-Zn aftersuitable activation (Boeing)Can also be repaired with brush-on SermaTel

AnodizingCan be anodized, leaving Al layer beneath anodizelayerWill improve wear and abrasion, but hard coating onsoft underlay not a good high load wear surface

Any form of Al avoids Cd embrittlementVery bad form of embrittlementCan occur when aborted takeoff heats brake discs andnearby landing gear components


Developments needed

Non-toluene solution needed for depot usePresent chemistry cannot be used in depots

Additional sources for plating serviceAdditional embrittlement testingWell-defined brush plate or other repair

Both for OEM and MRO use


Other ways to deposit Al

Arc or flame sprayUsed on some Bombardier aircraftThick coating (0.001 – 0.003”)RoughAl-Zn arc spray used on support equipment, radartowers, bombs

CVDGenerally high temperatureUsed for cooling passages in hot section bladesAFRL SERDP project approved for FY 04

Slurry Al – developed by Liburdi EngineeringHigh temperature heat treatFor hot section turbine blades (oxidation resistance)


SermeTel®

Metal-filled ceramics from SermaTech


SermeTel

Al flakes in ceramicmatrixBrush or spray onOlder formulationscontain Cr6+

Heat treat 375-700°FHard, glassy coating

Grit blast to uncover Al


Applications

Used in turbine enginesCases and discs

Landing gear in some older aircraft(commercial)F-22

Extensive use of SermeTel coatings on landing gearand other systemsSee Baltimore meeting on Materials Substitution forP2 in Advanced Aircraft (2002)



AdvantagesSimple spray or paint

Can be used for repairHard coating

Abrasion resistant

LimitationsSole source

Licensing to major usersonly (e.g. Goodrich)Others (inc. depots) mustsend to SermaTechVery high cost

Requires heat treatCan be low enough T forHSS

Embrittlement from acids informulation

When using 984/985 HE onA100 for F-22New formulation, not yettested or approved

Contains chromatesNew non-chromateformulations now available

Note: There are now someother similar coatings on themarket


Data available

Little publicly available data


Zn-Ni electroplate


Applications

Boeing uses acid Zn-NiRestricted to UTS<220 ksi because of embrittlementissues

Oklahoma City ALCReplaced Cd and TiCd with brush Cd, Zn-Ni and IVD in1991



AdvantagesAqueous electroplate

Easier application inopen tanks

Qualified processTank and brush plate

LimitationsAlloy chemistry

Difficult to ensurereproducibility anduniformity, especially oncomplex shapes

Embrittlement


Data available

Data available from Boeing, JGPP reporthttp://www.jgpp.com/projects/cadmium/jtr.htmlhttp://www.materialoptions.com/w2g/cgi/kmcgi.exe?O=DIR0000000I6D&V=0


Developments needed

Extension to high strength steelsNew JTP for HSS under way – Boeing, JGPP

Brush platingIs Zn-Ni a good repair for IVD or electroplated Al?


High strength stainless steel

S-53 – new steel developed by QuesTekInnovations LLC



AdvantagesNo coating to come offEliminates corrosion

Primary cause of landinggear overhaul and partscondemnation

Avoids SCCPrimary mechanism formajor landing gearfailure

LimitationsCannot be used uncoatedagainst AlMore expensive than300M

A bit less than cost ofA100


Developments needed

Full validation of properties and performanceDevelopment of materials databaseLicensing to steel producers so commerciallyavailable

QuesTek’s intent is licensing to several steelcompanies (QuesTek is a steel developer, not aproducer)


Data available

Extensive data will become availableover next 2 years from ESTCP program


HSSS properties

UTS

Fty

HT

+ L

N2 +

sin

gle

tem

per

HT

+ L

N2 +

dou

ble

tem

per

HT

+ l

on

ger

LN2 +

dou

ble

tem

per

HT

+ d

ry i

ce +

dou

ble

tem

per


Current status

Appears to be mechanically equivalent to 300Mbut much better fracture strength and SCCBeing tested and validated at Hill AFBWork to be complete in 3005Will obtain data needed for qualification

Not MIL Handbook 5 (requires 10 heats at$300,000/heat)Will do three heats to 20,000 lb

Then use AIM method (Accelerated Insertion ofMaterials) to interpolate between and extend lab datausing modeling data


Conclusion on Cd alternatives

Al is the best overall option, but depositionmethods are not straight “drop-in”

Electroplated Al looking increasingly good for OEMsIf adopted broadly, what about depot repair?

Non-toluene electroplate? IVD + sputtering?

High strength stainless exciting newdevelopment

Will be 2 or 3 years before it is fully qualified atOgdenEven then, no MIL Handbook 5 numbersModeling will tell us more about this steel than weknow about most others

There are niche applications for other Cdalternatives

chromium and cadmium replacement options for advanced … · advantages and limitations advantages...

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