Optical imaging of the sliding tracks shows the same bichromatic-to-monochromatic transition of the exposed surfaces as seen in the 5N load tests, becoming monochromatic at 1,600 revs. The sliding surface appears uniform up to 6,400 revs. However, on the 12,800 rev wear track, there is evidence of sliding fatigue; the surface of the sliding track contains deformations that run parallel to the sliding directions, as a consequence of sub-surface plastic deformation (Figure ). This is followed by the presence of a darkened material on the surface of the sliding track after 20,000 revs. EDS mapping supports the finding of a mechanically-formed copper-nickel sliding surface with reducing levels of nickel over longer sliding times. Summation of the EDS intensities shows that after 12,800 revs, the content of iron, nickel, chromium and molybdenum increases (arising from particle debris depositing from the wear of the 316SS counterface; Figure and Table ). This infers that the lowfriction performance of the coating fails, and a higher-wear sliding mechanism becomes dominant.