Tribological Behaviours Influenced by Surface Coatings and Morphology

Plasma electrolytic oxidizing (PEO) is an advanced technique that has been widely used in automotive industry to produce ceramic coatings on light metal components due to their high hardness, wear resistance, corrosion resistance and low friction coefficient. In this work, PEO process was used to produce a relatively thick (~20 μm) coating on A356 Al alloy for improving the wear resistance and tribological properties of the Al alloy. Effects of surface roughness and sliding velocity on the coefficient of friction (COF) of PEO coatings were particularly investigated in different tribological tests including low speed pin-on-disc tests, high speed pin-on-disc tests, and high speed piston ring on liner tests. Cast iron was used as reference material for comparison with PEO coatings. The research results indicated that the PEO coatings could have excellent tribological properties potential for linerless aluminium engine applications