PSI - Issue 60

350 Nagaraja Bhat Y V et al. / Procedia Structural Integrity 60 (2024) 345–354 Y V N Bhat, M A Davinci, A Kumar, N L Parthasarathi, S I S Raj, D Samataray, B.K. Sreedhar / StructuralIntegrity Procedia 00 (2019) 000– 000

to 30mm/s for given load. Wear debris with brownish colour was noticed after completion of 200 to 300 m sliding distance in every case. The brownish wear debris could be the result of oxidation.

Fig. 5. Microscope image of wear area of pin for case-4

Fig. 6. Confocal image of wear area of pin for case-5

Wear scars were studied using a Confocal Microscope. Images of the wear surface of pin for a couple of experiments are shown in Fig. 5 & 6. From the images, it can be concluded that the predominant mechanism of wear is abrasion or oxidative wear. As load increases the effect of oxidation was more which can be seen in the difference between fig. 5 & 6. The average dimensional wear coefficient (or specific wear coefficient, K H ) is calculated for the experiments. Calculations are carried out based on two standard methods viz. (a) on the basis of weight loss and (b) on the basis of wear diameter. Archard wear equation and cap formulae are used for calculations of specific wear coefficient as shown in appendix A. The values of specific wear coefficient, K H are provided in Table.3 and the values obtained from both methods are within the same range.

Table 3. Specific wear coefficient

K H (m 3 /Nm) From wear dia.

K H (m 3 /Nm) From weight loss

Weight loss (gm)

Final wear dia. (micron)

Case

0.0026

1798.000

1.243E-14

3.175E-14

Case – 1

Case – 2

0.0016

1963.211

2.32636E-14

2.564E-14

Case – 3

0.0031

2123.563

3.1962E-14

4.968E-14

Case – 4

0.0031

2032.233

2.67522E-14

4.968E-14

Case – 5

0.0039

2511.927

3.16036E-14

3.125E-14

From the Table-3, it can be concluded that, 'K H ’ is in the order 10 -14 m 3 /N-m. For both change in load and speeds, there is not much change in the K H value. Hence, it is concluded that the effect of speed and load on the K H is negligible in the studied domain. Specific wear coefficients are calculated from the different test results data as available in the literature (Gurumutrhy et.al., 2006, D. Kesavan et.al, 2010 & 2011) for the tribological experiments which were carried out with both pin and disc material made of Colmonoy-5 and testing were done at ambient condition. Wear coefficients calculated for the Colmonoy-5 are compared with maximum specific wear coefficient value obtained for 440C material from our work and plotted in the form of bar graph as shown in fig. 7. From the graph it is clear that specific wear coefficient of 440C material is almost one order less than the specific wear coefficients calculated for Colmonoy-5 material.