Prediction of DLC friction lifetime based on a local Archard factor density approach

8/18/2019 Prediction of DLC friction lifetime based on a local Archard factor density approach

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Prediction of DLC friction lifetime

based on a local Archard factor

density approach

F. ALKELAE , S. FOUVRY

International Conference on Metallurgical Coatings and Thin Films

April 29 – May 3, 2013San Diego, CA, USA


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SUMMARY

Experimental device

Material used

Experiments performed

Expertises performed

Friction analysis

Wear analysis

Endurance analysis based on Archard local energy density

2


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Q*,δ*

δ0≈δg

•

•

Experimental layout

Experimental device schema Fretting loop

3

P is kept constant

Q and are recorded

=> Plotting Q = f() : fretting loop

Materials data. Composition (Wt %) Young Modulus

(GPa)

52100 Chromium steel 97% Fe,1.45% Cr, 0.98% C,

0.35% Mn

210

DCY (DLC) 81.35% C, 16.92% W, 1.73%

Cr

364

Materials Data.


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Two families:

-Hydrogen free

-Hydrogen content

DLC’s

DLC categories

Conditions Valeurs

P (N) 5

δg (µm) 50

pmax (Mpa) 430

F (Hz) 25

T ( C) 20

RH (%) 29

52100 steel ball

DLC coating

52100 steel substrate

Configuration adopted

Experimental conditions

Work conditions and material used

4


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0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

F r i c t i o n c o e f f i c i e n t µ

Fretting cycles Nc

12

3 4

5

52100/52100

DLC/52100

Friction criterion (µth=0.3)

(I) (II) (III)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.E+00 2.E+06 4.E+06 6.E+06 8.E+06


Fretting cycles Nc

12

3 4

5

52100/52100

DLC/52100

Friction criterion (µth=0.3)

(I)

(II) (III)

Friction analysis

Linear representation of the

friction coefficient evolution

Logarithmic representation of the

friction coefficient evolution

5

Abrupt decrease on the friction coefficient after sequence 2.

continuous increase on the friction coefficient after sequence 2 until stabilizing at almost the

52100/52100 friction coefficient.


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1 2 3 4

5

Plane DLC fretting scars

Ball 52100 fretting scars

0.5mm

0.5mm

Wear analysis

Interrupted tests optical observations of the plane (above) and the ball

(bellow)

6


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500µm

-2µm

3D profiles

2D axial profiles

Surface

Coating thickness

3D profiles

1

2 3 4 5

Wear analysis

3D associated to 2D profiles of different interrupted tests

7


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1

2

3

4

5

SEM C W Cr Fe O Si

Wear analysis

SEM and EDX mapping of the plane fretting scar at different damage

sequences.

8


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(b)(a)

0 400 800 1200 1600

(a) Central zone

(b) DLC-ref

(a)

(b) ramanshift

(cm-1)

plane fretting scar analysis

(1)

0 400 800 1200 1600

(a) Central zone

(b) DLC-ref

(a)

(b)

(cm-1

)

(2)

(a) (b)(3)

0 400 800 1200 1600

(b) Debris (grey)

DLC-REFFeCr 2O4-ref.

(a) Central zone (bright)

(a)

(b)

(cm-1)

(4)

0 400 800 1200 1600

Fe2O3+Fe3O4-ref

(a) Central zone

(a)

raman

shift

(cm-1)

ball fretting scar analysis

0 400 800 1200 1600

(a) Central zone (black area)

DLC-ref

Cr 8O21(mixture of

CrO2 & Cr 2O3)

(b) External zone

(bright area)

Fe2O3+Fe3O4-ref

(a)

(b)

DLC-ref

(a)

(b)

(cm-1)

(a) Debris area(red) (b) Central zone

Fe2O3+Fe3O4-ref

(cm-1)0 400 800 1200 1600

0 400 800 1200 1600400 (cm-1)

(a) Central zone (bright)

FeCr 2O4-ref.

DLC-REF

(b) Black corona

CrC

(cm-1)0 400 800 1200 1600

DLC-ref

(b) Central zone

(bright area)(a) Central zone

(red area)

CrC

Fe2O3+Fe3O4-ref

CrC

CrC

Wear analysis

Raman analysis of plane and sphere fretting scar at different stages of the fretting wear

damage9


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31

µ = 0.4, Ra = 0.95µm _

µ = 0.2, Ra = 1.63µm _

Wear analysis

Roughness and friction coefficient comparison between sequence 1 and 3.

10

Remarkable friction coefficient of a smooth surface ( = 0.95µm) comparatively to a rough

surface ( = 1.63µm) =>

The polishing process is not the predominant parameter of the friction coefficient decrease from

sequence 1 to sequence 3 but rather the nature of the transfer layers.


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Coating

failureFriction faillure

µth = 0.3

(period I) (period II) (period III)

Nc1 Number of cycles


Nc2

Prediction of the interface endurance

Schematization of the friction interface evolution considering the coeting failure

(Nc1) and the friction failure (Nc2)

11

Nc1: the sharp decrease from the 0.4 friction plateau to the 0.2 friction plateau.

Nc2: the friction faillure which is defined by a friction value µ ≥ µ_th =0.3.


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y = -3E-05x + 169.25R² = 0.9517

0

20

40

60

80

100

120

0.0E+00 1.0E+06 2.0E+06 3.0E+06 4.0E+06 5.0E+06 6.0E+06

S l i d i n g a m p l i t u d e δ g (

± µ m )

Friction endurance Nc2

y = -6E-05x + 701.6

R² = 0.815

0

100

200

300

400

500

600

700

800

900

1 000

0.0E+00 1.0E+06 2.0E+06 3.0E+06 4.0E+06 5.0E+06

L o a d i n g p r e s s u r e p m a x

( M P a )



Evolution of the friction endurance Nc2 as a

function of the sliding amplitude(P = 5N).

Evolution of the friction endurance Nc2 as

a function of the contact pressure( =±50µm).

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The friction endurance seems to decrease while increasing the loading

pressure and the sliding amplitude.


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Pressure field illustration

Determination of the dissipated

local energy

13

The local dissipated energy analysis is conducted assuming Hertzian pressure field distribution.

The maximum Archard work density dissipated is situated at the center of the sphere/plane

interface (x = y = 0) following the Hertzian hypothesis

Illustration of the

Hertzian approach

methodology

1

23

4 Methodology ofcomputing the

simplified approach

g pW S max4~

e Arceea pW H H sin12~ 2

max


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0.0E+00

2.0E+04

4.0E+04

6.0E+04

8.0E+04

1.0E+05

1.2E+05

1.4E+05

1.6E+05

1.8E+05

2.0E+05

0.0E+00 1.0E+06 2.0E+06 3.0E+06 4.0E+06 5.0E+06 6.0E+06

L o c a

l A r c h a r d w o r k d e n s i t y

W S ( N . m / m 2 )


Nc2-dg=50µm / pmax var

Nc2-pmax-430MPa / dg var

Nc2 – δg =±50µm / pmax var

Nc2 – pmax = 430MPa/ δg var

y = -3E-09x2 + 0.003x + 11700R² = 1

0.0E+00

2.0E+04

4.0E+04

6.0E+04

8.0E+04

1.0E+05

1.2E+05

1.4E+05

0.0E+00 1.0E+06 2.0E+06 3.0E+06 4.0E+06 5.0E+06 6.0E+06 7.0E+06

L o c

a l A r c h a r d w o r k d e n s i t y

W H ( N . m / m 2 )


DCY : dg=50µm / pmax var

DCY : pmax=430 MPa / dg var



Evolution of the simplified Archard work

approximation

as a function of thefriction endurance Nc2


W

Evolution of the exact hertzian Archard

work approximation

as a function ofthe friction endurance Nc2

14

Large dispersion while using the simplified formulation especially for low endurance domain.

A good correlation obtained using the exact formulation which consider an elliptical distribution

of the contact pressure.


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0.0E+00

2.0E+04

4.0E+04

6.0E+04

8.0E+04

1.0E+05

1.2E+05

1.4E+05

0.0E+00 1.0E+06 2.0E+06 3.0E+06 4.0E+06 5.0E+06 6.0E+06

L o c a l A r c h a r d w o r k d e n s i t y

W H ( N . m / m 2 )

endurance Nc









Friction endurance

Coating endurance


Evolution of the applied Archard work density as a function of the coating

(Nc1) and the friction (Nc2) endurances

15

The coating endurance does not seem to be a function of the local Archard work density.

A good correlation between the friction endurance values represented as a function of the

local Archard parameter.


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Conclusion

DLC coatings are very interesting palliatives for fretting wear applications thanks to their very low riction

coefficient and wear rate

Since the evolution of the friction coefficient is devided into three phases, Raman spectroscopy, SEM and

EDX have shown that the transition from the first plateau of µ = 0.4 to the second of µ = 0.2 is monitored

by the formation of lubricious layers of DLC and chromium carbide, right after a little stabilization at this

second plateau, a continuous increase of the friction coefficient take place until almost reaching the

friction value of 52100/52100 contact.

A local Archard work density parameter was used to quantify the durability of the coating, two

endurances were taking into account, Nc1 : the coating faillure and Nc2 : the the friction faillure.

Nc2 > Nc1

Exact formulation and simplified formulation were plotted versus the friction endurance. A

remarkable dispersion was observed using , whereas a single master curve was obtained modeling

thus the wear evolution with the exact formulation.

For the coating endurance a vertical curve was obtained which means that it is not a function of the local

Archard work.


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Thank you for your

kind attention

Documents

Prediction of DLC friction lifetime based on a local Archard factor density approach