1. 2006. 5. 30. KIST-현대자동차 협력 포럼 KIST 미래기술연구본부 이 광 렬
엔진부품을 위한 카본계 내마모 윤활코팅
KIST-현대자동차 협력 포럼
KIST 미래기술연구본부
이 광 렬

2. Contents Brief Introduction to Diamond-like Carbon Coatings
Applications of DLC to Automobile Parts
DLC Research at KIST

3. 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

4. Bond Structure of Carbon
1S2 2S22P2

5. 2-D Analogy of Structure
a-C:H
ta-C

6. 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
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 (Wcm)
>1016
0.2 – 0.4

7. 경질코팅층의 내마모 윤활특성 DLC WC TiN CrN TiCN 마모도 마찰계수. 2.0 1.6 1.2 0.8 0.4
(상대비교치)
0.2
0.4
0.6
0.8
1.0
Against steel ball, 50% RH, RT
(Source : Nanotech Co. Ltd)

8. Applications of DLC CD/DVD Mold Form Die VCR Head Drum Spacer Tool
Razor Blade
Hard Disk & Slider
Digital VCR Tape
Wrist Pin

9. CarbofilmTM by Sorin Biomedica, Inc.
Applications of DLC
CarbofilmTM by Sorin Biomedica, Inc.

10. Deposition Methods Ion Source Energy Cold Substrate Impact Energy (eV)1 10
100
1000
Amorphous
Carbon
(sp2)
Dense
Source
Hydrocarbon
Hydro-
Polymer
Like
Plasma
Polymers
Ion Source
Energy
Cold Substrate

11. Ion Energy Distribution
PACVD

12. Examples of the Deposition Method
다음은 Si 함유 DLC 필름을 증착하는데 사용한 장비의 간략한 모식도와 증착조건 입니다 MHz를 사용한 R.F PACVD법을 사용하였고 Source Gas로는 벤젠과 수소로 희석된 Silane개스를 혼합하여 사용하였습니다.
증착압력은 10mtorr로 하였고, 바이어스 volatage는 -400V를 가하였습니다. 필름내 Si의 함량을 조절하기 위하여 혼합개스 내의 Silane개스의 함량을 0에서 90%로 변화시켜 가면 증착을 하였습니다.
기판은 Si(100)웨이퍼를 사용하였고, 필름의 두께는 1 micro meter로 증착하였습니다.
Si함량에 따른 마찰거동을 조사하기 위하여, Si이 포함되지 않은 순수한 DLC 필름과 Si이 0.5, 2, 9.5 at.% 함유된 DLC 필름을 제작하였습니다.

13. 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.
Momentum development for typical 2 liter Petrol and Diesel engines over 35 years.
(Source : Dr. Hauzer)

14. 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

15. Friction Loss in Engine
camshaft
tappets
valves
piston
piston rings
crankshaft
(Source : Dr. Hauzer, 2005)

16. Available Coatings at Present
Carbon based
Nitride based
Me-C:H
a-C:H
Me a-C
a-C
CrN
TiN
Production method
PVD/PACVD
PACVD
PVD
Hardness
(HV 0.05)
Friction coefficient
0.4
0.7
Internal stress
(GPa)
1-3
2-6
0.1-1
0.5-2
Thickness (µm)
1-10
1-5
1-40
1-8
Practical problems
+++ ++
Process stability +
Industrial
experience -
(Source : ICMCTF 2005 / 2006)

17. Coating Technology for Automobile Engines
(Source : Dr. Hauzer, 2005)

18. Penetration Fraction of PVD (2006)
Diesel Pump % 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

19. 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 application
for minimum wear and power consumption

20. Nanocomposite / Multilayer
5nm
5nm
W-DLC by Hybrid Ion Plating (KIST)
CrC/W-DLC Multilayer (Hauzer)

21. Fuel Injection System Part: Diesel fuel injector and plunger
Coating: a-C:H, W-C:H with metallic buffer
Coating thickness >1 μm
Benefit Wear resistance, preventing seizure
2000~3000bar
Figure from Robert Bosch GmbH

22. Unit Injection System (1.9TDI)
Technical Data
Engine power: 96 KW (130 PS)
Injection pressure: 2050 bar
Pressure power: N
Advantages
Increased efficiency (lower friction)
Increased engine torque
Reduce energy consumption
Reduction of the CO2-emission
Source: Volkswagen AG, Wolfsburg

23. Rocker Arm + Hydraulic Element
Valve Train
Tappets
Rocker Arm + Hydraulic Element
Coating CrN, a-C:H:W/Cr
Si-DLC/Si
Thickness – 6 µm
Coating on Top side
Benefit Wear + friction
Coating Endurance+
Release
Thickness – 5 µm
Coating on Head hydraulic
element
Rockerarm
(racing)
Benefit Wear
(Source : Dr. Hauzer)

24. 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)

25. DLC Application by Nissan
日經 BP 2006/03/15 21:15
Compatibility with special lubricant
of different additives (m = 0.07)
연말 실용화 목표

26. 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

27. Door Lock to reduce noise

28. Coating Technology for Automobile Engines
(Source : Dr. Hauzer, 2005)

29. 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

30. Applications of DLC CD/DVD Mold Form Die VCR Head Drum Spacer Tool
Razor Blade
Hard Disk & Slider
Digital VCR Tape
Wrist Pin

31. Technology Transfer to Industry
J&L Tech Co. Ltd
Daewoo Electronics Co.

32. Application to Top Ring
Required Properties of Top Ring
Anti-scuffing
Wear Resistance
Low Friction Coefficient
Chemical Stability
Self Lubrication
Low Cost
Schematics of Diesel Engine

33. ~10mm Thick Films Deposition Method
250KHz PACVD using CH4 at 200 mTorr
Cylinder Coating Technology (analogy to VCR Head Drums)
Buffer Layer Design for Optimum Adhesion
~10mm Thick Films

34. Reciprocal Tribometer (Plint 77)
sliding direction
piston ring
cylinder liner
(boron cast iron)

35. Anti-scuffing Property of Piston Rings
Test condition :
load :200N, marginal lub. condition
250
200
150
Time to failure(hour)
100 50 Cr
WS2-1
WA2-2 GN
PVD
DLC

36. Wear Test under Dry Lubrication Conditions

37. Result of Dynamo Test (900h)
Hard Cr Coated Ring
DLC coated Ring
Before Test
Before Test
After Test
After test

38. Hard Cr Coated Piston Ring DLC/Cr Coated Piston Ring Before Test
6.5mm
100mm
Before Test
Before Test
5.3mm
After Test
After Test

39. Issues in Carbon Base Coatings
Adhesion
In most cases, film adhesion is more important than the 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