Duplex coatings comprising MoS2/Sb2O3/graphite layer burnished on top of plasma electrolytically oxidised AA6082 alloy enhanced fretting wear resistance against alumina and steel whilst reducing friction from 0.6…0.9 to 0.08…0.1 in dry nitrogen and humid air. Transitions to stick-slip (~3 m), partial slip (5-10 m) and gross slip (>10 m) showed an order of magnitude improvements over single-layer PEO coatings. In the latter mode, high initial contact pressures (1.1 GPa) with steel counterpart under oxidising atmosphere increased friction due to generation of Fe/Al/Cr oxides/hydroxides in the contact region, leading micro-cracking in PEO coating followed by fatigue damage of aluminium substrate. Reducing contact pressure <1 GPa, retained topcoat lubricating behaviour, high wear resistance and eliminated fatigue damage after 104 cycles.
|Publication status||Accepted/In press - 10 Oct 2020|