Comparing the features of the G-and D-bands from the wear tracks formed on ML (Ni) at 5N and 25N, it is clear to see that the evolution of the GnP tribofilm is consistent; for example, the peak position of the G-band shifts from 1603 to 1601 cm -1 when sliding time is increased from 100 revs to 10,000/12,800 revs, respectively. Comparison of ML (Ni) and ML (Cu) at 5N, however, shows that the exclusion of a nickel top-coating has a significant effect on the degradation of the GnP tribofilm. The G-peak for ML (Cu) after 100 revs sliding is already at ~1602 cm -1 , with further shifts down to 1595 cm -1 by 6,400 passes. Similar trends were seen with the D-peak position and G-peak FWHM; ML (Ni) sliding performed at both 5 and 25N