1. Indo-Turkey Tripartite Program – Visit to IIT Kanpur
Shri Awadesh Kumar Mallik
Scientist Gr IV (1)
Central Glass & Ceramic Research Institute, CSIR India

2. Fretting Wear Tester

3. Fretting Test Conditions - linear relative reciprocatory displacement sliding
Ball-on-Flat configuration
Normal Load 8 N constant
Stoke Length – 100 μm
Frequency – 6 Hz
No. of Cycles – 45000
Sliding Distance – 9 m
Reciprocating Velocity – 1.2 mm/sec
Unlubricated
Temperature oC
Relative Humidity 50%-52% 8N
100 μm, 6 Hz, cycles

4. Types of Counterbodies
B % SiC Flat
High Temperature Pressure Less Sintering SiAlON Flat
6 mm diameter Al2O3 balls
10 mm diameter Al2O3 balls
10 mm diameter Si3N4 balls

5. Properties of Counterbodies

6. Roughness before Fretting

7. Friction Curves – SiC Composite
6 mm Al2O3
Running-in Period cycles
6 mm Al2O3
10 mm Al2O3
10 mm Si3N4

8. Friction Curves - HTPLS
Running-in Period cycles
6 mm Al2O3
10 mm Al2O3
10 mm Si3N4

9. 3D profile of worn surfaces – SiC Composite
10 mm Al2O3
10 mm Si3N4

10. 3D profile after fretting – HTPLS
10 mm Al2O3

11. 2D profile after fretting SiC Composite
6 mm Al2O3
10 mm Al2O3

12. 2D profile after fretting – SiC Composite
10 mm Si3N4 - SiC

13. Steady state Average COF
Wear & Friction Values
Sample
Steady state Average COF
Wear Volume
mm3
Wear Rate
mm3N-1m-1
SiC vs 6 mm Al2O3
0.55
7.25 Χ 10-4
1.003 Χ 10-5
SiC vs 10 mm
Al2O3
6.1 Χ 10-4
8.472Χ 10-6
SiC vs 10 mm Si3N4
3.1 Χ 10-4
4.305 Χ 10-6
HTPLS vs 6 mm Al2O3
0.69
1.452 Χ 10-3
2.016 Χ 10-5
HTPLS vs 10 mm Al2O3
1.247 Χ 10-3
1.731 Χ 10-5
HTPLS vs 10 mm
Si3N4
1.636 Χ 10-4
2.272 Χ 10-6

14. Optical Images of Wear Scar – SiC Composite
6 mm Al2O3
6 mm Al2O3
10 mm Al2O3
10 mm Si3N4

15. Optical Micrograph of Wear Scar of HTPLS
6 mm Al2O3
6 mm Al2O3
10 mm Al2O3
10 mm Si3N4

16. SEM Images of Wear Scars – Least Worn SiC composite against 10 mm Si3N4 balls
Tribo-islands
Sliding direction
Wear debris
inside
tribo-island
Grain
Pull-out

17. Oxygen rich triboislands
Possible Chemical reaction under stress & temperature 2 SiAlON O2 = 2 SiO2 + Al2O3 + N2
SEM images with EDAX
Element
Weight %
Weight % σ
Atomic %
Carbon
9.726
1.524
16.801
Oxygen
35.956
0.752
46.628
Sodium
0.387
0.102
0.350
Aluminum
3.605
0.115
2.772
Silicon
43.629
0.824
32.230
Potassium
0.372
0.059
0.197
Calcium
0.487
0.061
0.252
Gallium
0.094
0.182
0.028
Samarium
4.171
0.249
0.576
Gold
1.574
0.305
0.166
Abrasive Grooves
Oxygen rich triboislands
Element
Weight %
Weight % σ
Atomic %
Carbon
5.451
0.766
9.225
Nitrogen
32.904
1.039
47.756
Oxygen
3.618
0.457
4.597
Aluminum
2.390
0.091
1.801
Silicon
49.328
0.892
35.705
Calcium
0.292
0.057
0.148
Gallium
0.071
0.179
0.021
Samarium
4.194
0.248
0.567
Gold
1.752
0.306
0.181

18. Highest Worn SiC Composite vs 6 mm Al2O3 ball
Sliding direction
Crack Propagation
&
Fragmentation of Tribo-islands
Spalling of tribolayer and wear debris

19. Oxygen rich triboislands
Possible Chemical reaction under stress & temperature 2 SiAlON O2 = 2 SiO2 + Al2O3 + N2
SEM with EDAX
Abrasive Grooves
Element
Weight %
Weight % σ
Atomic %
Carbon
1.721
1.011
2.915
Oxygen
51.630
0.663
65.654
Sodium
2.308
0.116
2.042
Aluminum
8.621
0.168
6.500
Silicon
29.702
0.416
21.516
Potassium
1.578
0.080
0.821
Samarium
2.925
0.220
0.396
Gold
1.515
0.298
0.156
Oxygen rich triboislands
Element
Weight %
Weight % σ
Atomic %
Carbon
3.710
0.762
6.169
Nitrogen
34.832
0.892
49.673
Oxygen
4.906
0.487
6.125
Aluminum
2.293
0.086
1.697
Silicon
50.435
0.822
35.870
Gallium
0.000
Samarium
2.448
0.221
0.325
Gold
1.377
0.300
0.140

20. Wear Mechanisms Formation of scattered oxygen rich Tribo-islands
Abrasive wear grooves along sliding direction
Wear particles on abrasive grooves
Crack propagation causing fragmentation of tribolayers
Spalling of Tribo-island
Wear debris in and around tribo-islands
Grain Pull-out
Oxidation of abrasive wear particles

21. Low Friction due to Higher Hertzian Contact for bigger balls
Hertzian Contact Pressure Po,
Where Po = (3/2) Pm = (6WE *²/π³R²)
The initial Contact Diameter is given by,
a = (3WR/4E*)⅓
W is the applied load E* is effective Elastic modulus & R is the radius of the ball
For a given load 8 N as the ball diameter increases from 6 mm to 10 mm initial contact diameter increases which thereby reduces Hertzian contact pressure Po and hence lower resistance to motion (COF)

22. SEM of Unworn Surfaces