GO-CMMC (0.25CD) , on the other hand, shows penetration into the bulk-copper surface. GO-CMMCs succumb to wear of the bulk coating as a consequence of the lower area coverage of such growths on its surface (~ 10% of the surface area, c.f. > 40% for FGO-CMMCs; Table ). It is also noted that the high μ observed has given rise to coating fracturing, delamination and erosion, resulting in microparticle-type debris redistributing along the sliding track. This was also observed after sliding on Cu Ref coatings (Figure ). The high-friction running on the coating is also anticipated to inhibit the formation of a robust tribofilm on the sliding track, as shown by the lack of surface carbon in the EDX map (Figure ).