Environmental Dependence onEnvironmental Dependence on Tribological Behavior of Diamond-like Carbon Films Tribological Behavior of Diamond-like Carbon Films

with Nano-undulated Surfacewith Nano-undulated Surface

Jin Woo Yi Jin Woo Yi a,ba,b, Se Jun Park , Se Jun Park aa, Kwang-Ryeol Lee , Kwang-Ryeol Lee aa, Seock-Sam Kim , Seock-Sam Kim bb

aa Korea Institute of Science and Technology, Seoul, Korea Korea Institute of Science and Technology, Seoul, Korea

bb Kyuongpook National University, Daegu, Korea Kyuongpook National University, Daegu, Korea

THE INTERNATIONAL CONFERENCE ON THE INTERNATIONAL CONFERENCE ON METALLURGICAL COATINGS AND THIN FILMSMETALLURGICAL COATINGS AND THIN FILMS

ICMCTF 2006ICMCTF 2006May 1-5, 2006.May 1-5, 2006.

Town and Country Hotel, San Diego, California, USATown and Country Hotel, San Diego, California, USA

22

Merit of Diamond-like CarbonMerit of Diamond-like Carbon

TiNTiN

WCWC

TiCNTiCN

CrNCrN

DLCDLC

2.0 1.6 1.2 0.8 0.4 0.2 0.4 0.6 0.8 1.0

TiNTiN

WCWC

TiCNTiCN

CrNCrN

DLCDLC

2.0 1.6 1.2 0.8 0.4 0.2 0.4 0.6 0.8 1.0

Wear RateWear Rate Friction CoefficientFriction Coefficient

33

Demerit of Diamond-like CarbonDemerit of Diamond-like Carbon

• The frictional behaviors of DLC film largely depends on The frictional behaviors of DLC film largely depends on environmentalenvironmental conditions such as conditions such as relative humidityrelative humidity..

A.Gilmore et al., Surf. Coat. Technol., 133-134 (2000) 437A.Gilmore et al., Surf. Coat. Technol., 133-134 (2000) 437

44

Humidity Dependence Humidity Dependence of Frictional Behavior of DLC filmof Frictional Behavior of DLC film

S.J.Park et al., Diamond Relat. Mater. 12 (2003) 1517S.J.Park et al., Diamond Relat. Mater. 12 (2003) 1517

Relative Relative humidityhumidity

Friction Friction coefficientcoefficient

• Formation of Fe-rich debrisFormation of Fe-rich debris (Degradation of lubricant properties of DLC film)(Degradation of lubricant properties of DLC film)

• Increase of the debris sizeIncrease of the debris size

55

Possibility of Nano-undulated Surfaced DLC filmPossibility of Nano-undulated Surfaced DLC film

• DLC film with nano-undulated surface could suppress the DLC film with nano-undulated surface could suppress the dependence of environmental conditions.dependence of environmental conditions.

S.J. Park et al., Diamond Relat. Mater., 14 (2005) 1291-1296S.J. Park et al., Diamond Relat. Mater., 14 (2005) 1291-1296

66

Purpose of This WorkPurpose of This Work

• Tribological behavior of nano-undulated DLC film surface Tribological behavior of nano-undulated DLC film surface with various surface roughness in with various surface roughness in different humid different humid environmentsenvironments..

• Investigating the relationship between the Investigating the relationship between the surface roughness surface roughness and theand the humidity dependence on frictional behavior humidity dependence on frictional behavior of DLC of DLC filmsfilms

77

Fabrication of Fabrication of DLC Film with Nano-undulated SurfaceDLC Film with Nano-undulated Surface

AnnealingAnnealingNi-thin FilmNi-thin Film

•DC magnetron sputter• Deposition Pressure : 1.33 Pa• Current : 200 mA• Voltage : -430 V• Film Thickness : 3 ~ 9 nm

DLC film with DLC film with undulated surfaceundulated surface

•RF PACVD (13.56MHz)• Precursor Gas : CH4

• Deposition Pressure : 1.33 Pa• Bias Voltage : -150 Vb

• Film Thickness : 100±10 nm

DLC DepositionDLC Deposition

88

0 2 4 6 8 10

0

2

4

6

8

10

12

14

R

MS

Rou

ghn

ess

(nm

)

Thickness of Ni Film (nm)

Surface Roughness of DLC FilmsSurface Roughness of DLC Films

RRMS=9.4 nmRRMS=9.4 nm

RMS=8.1 nmRMS=8.1 nm

RMS=0.1 nmRMS=0.1 nm

RRMS=11.8 nmRRMS=11.8 nm

99

Raman SpectraRaman Spectra

800 1000 1200 1400 1600 1800 2000800 1000 1200 1400 1600 1800 2000800 1000 1200 1400 1600 1800 2000800 1000 1200 1400 1600 1800 2000

Inte

nsit

y (a

.u.)

Raman Shift (cm-1)

RMS 0.1 nm

Inte

nsit

y (a

.u.)

Raman Shift (cm-1)

RMS 8.1 nm

Inte

nsit

y (a

.u.)

Raman Shift (cm-1)

RMS 9.4 nm

Inte

nsit

y (a

.u.)

Raman Shift (cm-1)

RMS 11.8 nm

0 2 4 6 8 10 121480

1490

1500

1510

1520

1530

1540

G-p

eak

Posit

ion

(cm

-1)

Surface Roughness (nm)

1010

Environmental Tribo-meterEnvironmental Tribo-meter

•Wear-test conditionWear-test condition– Counter-ball : Steel bearing ball

(Dia. 6 mm)

(AISI 52100)

– Normal load : 200 gf (2 N)

– Sliding speed : 11.5 cm/sec

– Relative Humidity : 0 ~ 90 %

– @ room temperature

– Running Time : 10,000 cycles

WeightWeight

Load CellLoad Cell

Counter-Counter-ball Holderball Holder

FilmFilm

RotationRotation

Humid Controller

Rotary Pump

1111

Frictional BehaviorFrictional Behavior

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 0 %

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 50 %

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 90 %

RMS 0.1 nm

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 0 %RMS 8.1 nm

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 50 %

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 90 %

Fri

ctio

n C

oeff

icie

nt

Cycles

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 50 %

RMS 9.4 nm

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 0 %

Fri

ctio

n C

oeff

icie

nt

Cycles

RH 90 %

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

0 2,000 4,000 6,000 8,000 10,0000.0

0.2

0.4

0.6

Fri

ctio

n C

oeff

icie

nt

Cycles

R.H. 50 %

RMS 11.8 nm

Fri

ctio

n C

oeff

icie

nt

Cycles

R.H. 0 %

Fri

ctio

n C

oeff

icie

nt

Cycles

R.H. 90 %

Fri

ctio

n C

oeff

icie

nt

Cycles

Fri

ctio

n C

oeff

icie

nt

Cycles

1212

Mean Friction CoefficientMean Friction Coefficient

0 2 4 6 8 10 120.0

0.1

0.2

0.3

0.4

RH 0 % RH 50 % RH 90 %

Ave

rage

Fri

ctio

n C

oeff

icie

nt

Surface Roughness, Rq (nm)

1313

0 500 1000 1500 2000

Si

FeO

RH 0%

RH 90%Inte

nsity

(a.u

.)

Kinetic Energy (eV)

RH 50%C

RMS 11.8 nm, After Cleaning

0 500 1000 1500 2000

SiFeO

RH 0%

RH 90%Inte

nsity

(a.u

.)

Kinetic Energy (eV)

RH 50%C

RMS 0.1 nm, After Cleaning

Auger Spectra of Wear DebrisAuger Spectra of Wear Debris

1414

500 1000 1500 2000

Inte

nsit

y (a

.u.)

Raman Shift (cm-1)

RMS 11.8 nm

RH 0 %

RH 50 %

RH 90 %

500 1000 1500 2000

Inte

nsit

y (a

.u.)

Raman Shift (cm-1)

RMS 0.1 nm

RH 0 %

RH 50 %

RH 90 %

Raman Spectra of Transfer LayerRaman Spectra of Transfer Layer

1515

Morphology of Transfer LayerMorphology of Transfer Layer

200μm

RH 0% RH 50% RH 90%

RH 0% RH 50% RH 90%

RMS 0.1 nmRMS 0.1 nm

RMS 11.8 nmRMS 11.8 nm

200μm 200μm

200μm 200μm 200μm

Fe-oxide Fe-oxide debrisdebris

• Diamond-likeDiamond-like• No Fe-oxideNo Fe-oxide

Wear ScarWear Scar

1616

In Relative Humidity 90 %In Relative Humidity 90 %

Transfer LayerTransfer LayerFe-oxide ParticleFe-oxide Particle

Fe-oxideFe-oxide

Transfer LayerTransfer LayerFe-oxide ParticleFe-oxide Particle

Fe-oxideFe-oxide

In case of DLC film In case of DLC film with smooth surfacewith smooth surface

In case of DLC film In case of DLC film with rough surfacewith rough surface

DiscussionDiscussion

1717

ConclusionsConclusions

Controlling the surface roughness of DLC film in nano-scale can Controlling the surface roughness of DLC film in nano-scale can suppress the environmental dependence on frictional behavior of suppress the environmental dependence on frictional behavior of DLC film.DLC film.

- In case of DLC film with smooth surface, the bond structure of transfer - In case of DLC film with smooth surface, the bond structure of transfer layer reveals graphitic materials and a lot of Fe-oxide is observed in layer reveals graphitic materials and a lot of Fe-oxide is observed in the transfer layer with increase of relative humidity.the transfer layer with increase of relative humidity.

- In case of DLC film with rough surface, the bond structure of transfer - In case of DLC film with rough surface, the bond structure of transfer layer reveals diamond-like materials and less Fe-oxide is observed in layer reveals diamond-like materials and less Fe-oxide is observed in the transfer layer.the transfer layer.

1818

TThanks for hanks for YYour our

AAttentionttention!!!!!!TThanks for hanks for YYour our

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