Deconvolution of the GnP-related peaks from the acquired spectra can also provide evidence for the evolution of the GnP tribofilms within the two coating systems. The relative peak shapes, peak positions and intensity ratios are known to give insights into the nature of graphitic materials in literature. In our assessment, we do not include data points that have previously shown that coating performance has failed (i.e. ML (Ni) 20,000 revs sliding at 25N, and ML (Cu) 10,000 revs sliding at 5N load; indicated by the crossed data points in the graphs)