Effects of Ce(SO4)2 concentration on the properties of micro-arc oxidation coatings on ZL108 aluminum alloys

Micro-arc oxidation coatings were deposited on ZL108 aluminum alloys in silicate-hydroxide electrolytes containing 0, 0.2, 0.4, 0.6 and 0.8 g/L Ce(SO4)2 respectively. The oxidation voltages, surface morphologies, phase composition, polarization curves, micro-hardness and thickness of MAO coatings were investigated. With the increasing of Ce(SO4)2, the oxidation voltages increased firstly and decreased gradually along with the variation of the coating thickness. The addition of Ce(SO4)2 could improve the homogeneity and corrosion resistance of the MAO coatings, while the surface micro-hardness increased firstly and decreased finally. There was little influence of Ce(SO4)2 on the phase composition of MAO coatings.