Plasma electrolytic Oxidation coatings for engine components

This work summarizes the corrosion, tribological and tribocorrosion response of different Plasma Electrolytic Oxidation (PEO) coatings developed on aluminium-silicon alloys destined to replace cast iron liners in a total aluminium engine block, as well as the tribological behaviour of Mg pistons improved with PEO treatments as possible candidates for Al pistons replacement. 

In the first part of this study, the Al-7Si alloy was coated by using plasma electro oxidation technique and different thicknesses and surfaces properties were checked. The tribological response of coated samples was studied by means of tribological tests under piston ring/cylinder liner configuration simulating the real working conditions. The corrosion improvement by applying the coating was studied by periodic measurements of electrochemical impedance spectroscopy inK2SO4 0.2 M solution. In the second part of the study, different PEO treatments were applied on the MRI201S Mg alloy samples, as well as on a real Mg piston prototype. The tribological behaviour of the developed surfaces was analyzed by means of simulation tests.