For baseline performance, GnP-free ML (Ni) was tested first. After running for 10,000 revs, the sliding tracks on the GnP-free coatings show clear penetration into the underlying steel surface. The load applied dictates the level of penetration that has occurred: 1.3N sliding reveals the beginning of coating failure, shown by the fine steel line exposed in the centre of the track (Figure ). Increasing loads further accelerate the wear of the copper layer, with larger areas of steel exposure observed after 5N and 10N sliding. The CoF traces from the sliding tests reveal the point of coating penetration (Figure ); for 10N sliding, after the initial run-in phase, friction levels reduce to ~0.65, before abruptly increasing after approximately 1,000 revs sliding after the onset of steel-on-steel contact. The point of failure at 5N sliding is ~1,850 revs, and for 1.3N sliding is not clear, as the CoF increase is significantly slower, coupled with a reduced level of penetration seen on the wear track after 10,000 revs.