엔진부품을 위한 카본계 내마모 윤활코팅 2006. 5. 30. kist- 현대자동차 협력...
TRANSCRIPT
엔진부품을 위한 카본계 내마모 윤활코팅
2006. 5. 30.KIST- 현대자동차 협력 포럼
KIST 미래기술연구본부 이 광 렬
Contents
• Brief Introduction to Diamond-like Carbon Coatings
• Applications of DLC to Automobile Parts
• DLC Research at KIST
What is DLC ?
• Amorphous Solid Carbon Film• Mixture of sp1, sp2 and sp3 Hybridized Bonds• High Content of Hydrogen (20-60%)
• Synonyms– Diamond-like Carbon– (Hydrogenated) amorphous carbon (a-C:H)– i-Carbon– Tetrahedral Amorphous Carbon
Heart valve Hard disk
Bond Structure of Carbon
1S2 2S22P2
a-C:H ta-C
2-D Analogy of Structure
Properties of Solid Carbon
Property Diamond DLC Graphite
Density (g/cm3) 3.51 1.8 – 3.6 2.26
Atomic Number Density (Mole/cm3)
0.3 0.2 – 0.3 0.2
Hardness (Kgf/mm2) 10000 2000 - 8000 500
Friction Coeff. 0.05 0.03 – 0.2 0.1
Refractive Index 2.42 1.8 – 2.6 2.15 – 1.8
Transparency UV-VIS-IR VIS-IR Opaque
Resistivity (cm) >1016 1010 - 1013 0.2 – 0.4
경질코팅층의 내마모 윤활특성
DLC
WC
TiN
CrN
TiCN
마모도 마찰계수 .
2.0 1.6 1.2 0.8 0.4 0.2 0.4 0.6 0.8 1.0( 상대비교치 )
Against steel ball, 50% RH, RT(Source : Nanotech Co. Ltd)
Applications of DLC
VCR Head Drum
CD/DVD Mold
Spacer Tool
Form Die
Hard Disk & Slider
Digital VCR Tape
Razor Blade
Wrist Pin
Applications of DLC
CarbofilmTM by Sorin Biomedica, Inc.
Deposition Methods
Energy
Ion Source
Cold SubstrateIm
pact
Ene
rgy
(eV
)1
10
100
1000
Amorphous Carbon
(sp2)
DenseCarbon
CarbonSource
HydrocarbonSource
DenseHydro-Carbon
PolymerLike
Carbon
PlasmaPolymers
PACVDPACVD
Ion Energy Distribution
Examples of the Deposition Method
Development of Diesel Engines
• Diesel engines are designed with continuously increasing power densities since the introduction of HP-fuel injection systems (1993).
• Power and torque of diesel engines increased at a much higher rate than gasoline engines.
• Meet environmental laws and cost reduction requirements.
0
100
200
300
400
1970 1975 1980 1985 1990 1995 2000 2005
Year
Nm Diesel
Petrol
(Source : Dr. Strondl @ Hauzer)
Momentum development for typical 2 liter Petrol and Diesel engines over 35 years.
Driving Force : Economy and Environment
• Reduction of Energy Consumption– Reduction of friction
• Reduction of Emission– Higher pressure fuel injection– Predictable wear of piston ring
• Cost Reduction– Reduction of parts number
e.g. sliding bearing instead of needle bearing coated piston pin coated tappet
• Wear Protection– Higher load per surface area
Friction Loss in Engine
(Source : Dr. Strondl @ Hauzer, 2005)
camshafttappets
valves
piston
piston rings
crankshaft
Carbon based Nitride based
Me-C:H a-C:H Me a-C a-C CrN TiN
Production method
PVD/PACVD PACVD PVD PVD PVD PVD
Hardness (HV 0.05)
800-2200 1500-3500 1500-2500 2000-7000 2000-2200 2000-2200
Friction coefficient
0.1-0.2 0.02-0.1 0.05-0.1 0.02-0.1 0.4 0.7
Internal stress (GPa)
0.1-1.5 1-3 1-3 2-6 0.1-1 0.5-2
Thickness (µm) 1-10 1-3 1-5 1-3 1-40 1-8
Practical problems
+++ ++Process stability
+ +++ +++
Industrial experience
+++ ++ - - +++ +++
Available Coatings at Present
(Source : ICMCTF 2005 / 2006)
(Source : Dr. Strondl @ Hauzer, 2005)
Coating Technology for Automobile Engines
Penetration Fraction of PVD (2006)
• Diesel Pump 100% since 1994
• Crankshaft Bearing 100% since 1987
• Piston Ring 10% since 1993
• Valve train (Tappet) 2% since 2001
• Piston Pin 1% since 2002
• Gear < 1% since 2000
Demands in Automobile Applications
• Low wear of Coated Part– Suppress abrasive wear– Suppress adhesive wear– Suppress fatigue wear
• Low Wear on Counterpart• Low Coefficient of Friction
Composition
Multilayer structure
Microstructure
Optimized to the applicationfor minimum wear and power consumption
Nanocomposite / Multilayer
CrC/W-DLC Multilayer (Hauzer)W-DLC by Hybrid Ion Plating (KIST)
5nm
5nm
Part: Diesel fuel injector and plungerCoating: a-C:H, W-C:H with metallic bufferCoating thickness >1 μmBenefit Wear resistance, preventing seizure
Figure from Robert Bosch GmbH
Fuel Injection System
2000~3000bar
Technical Data
Engine power: 96 KW (130 PS)
Injection pressure: 2050 bar
Pressure power: 14.000 N
Advantages
• Increased efficiency (lower friction)
• Increased engine torque
• Reduce energy consumption
• Reduction of the CO2-emission
Source: Volkswagen AG, Wolfsburg
Unit Injection System (1.9TDI)
Valve Train
Tappets Rocker Arm + Hydraulic Element
Coating CrN, a-C:H:W/Cr Si-DLC/SiThickness 2 – 6 µmCoating on Top side
Benefit Wear + friction
Coating Endurance+
ReleaseThickness 1 – 5 µmCoating on Head hydraulic element
Rockerarm (racing)
Benefit Wear
(Source : Dr. Strondl @ Hauzer)
Piston Ring
- Sliding contact- Abrasive wear (also liner to be protected)- Temperature load
Coating 200 µm hard Cr (galvanic)30-40 µm CrN (PVD Arc)~10 µm DLC (PACVD) / Me-DLC (PVD)
(Source : KIST & DHI 1996)
DLC Application by Nissan
日産自動車,水素フリー DLC コーティングによる摩擦低減技術を開発
日經 BP 2006/03/15 21:15
Compatibility with special lubricant of different additives ( = 0.07)연말 실용화 목표
Gears
Full oil film lubrication DLC has not shown a beneficial influence.
Boundary lubrication (stopping/starting, severe load, temporary loss of lubricant) DLC coatings can significantly reduce wear.
Maximum load carrying capacity of gears can be increased by 10-40%.
Coated spur gear
Door Lock to reduce noise
(Source : Dr. Strondl @ Hauzer, 2005)
Coating Technology for Automobile Engines
DLC Research @ KIST
• Synthesis and Application of DLC Films– Control of structure and properties of DLC films– Modification of DLC films by third element addition– Nanoscale structure manipulation for novel functions– Tribo-chemical Aspect of DLC Films– Mechanical Properties of Thin DLC Films– Application technologies
• Adhesion improvement• Coating layer optimization• Production process development
http://diamond.kist.re.kr/DLC
Applications of DLC
VCR Head Drum
CD/DVD Mold
Spacer Tool
Form Die
Hard Disk & Slider
Digital VCR Tape
Razor Blade
Wrist Pin
Technology Transfer to Industry
J&L Tech Co. Ltd
Daewoo Electronics Co.
Required Properties of Top Ring
– Anti-scuffing– Wear Resistance– Low Friction Coefficient– Chemical Stability– Self Lubrication– Low Cost
Application to Top Ring
Schematics of Diesel Engine
Deposition Method
• 250KHz PACVD using CH4 at 200 mTorr• Cylinder Coating Technology
(analogy to VCR Head Drums)• Buffer Layer Design for Optimum Adhesion
~10m Thick Films~10m Thick Films
Reciprocal Tribometer (Plint 77)
sliding directionpiston ring
cylinder liner(boron cast iron)
Anti-scuffing Property of Piston Rings
Cr WS2-1 WA2-2 GN PVD DLC0
50
100
150
200
250T
ime
to
fa
ilure
(ho
ur)
Test condition :load :200N, marginal lub. condition
Wear Test under Dry Lubrication Conditions
0 5000 10000 15000
0.2
0.3
0.4
0.5
DLC coated Ring
Hard Cr Ring
No-lubricant conditionLoad 50N
Fric
tion
Coe
ffic
ient
Number of Cycle.
Hard Cr Coated Ring DLC coated Ring
Before Test Before Test
After Test After test
Result of Dynamo Test (900h)
Before Test Before Test
After Test After Test
100m6.5m
5.3m
Hard Cr Coated Piston Ring
DLC/Cr Coated Piston Ring
Issues in Carbon Base Coatings
• Adhesion– In most cases, film adhesion is more important than th
e mechanical properties.
• Environmental Effects– Compatibility with new lubricants– Adhesion degradation in aqueous environment
• Tribochemical Reaction for Fundamentals– In-situ observation of the contact surfaces– Third element effect– Multilayer effect
• Market Penetration– Based on the advanced technology