Effects of Electrolyte Composition on the Properties of Micro-Arc Oxidation Coatings Formed on 6063 Alloy

Micro-arc oxidation (MAO) coating was prepared in different electrolyte compositions on 6063 alloy and its characterizations were detected by X-ray diffractometer (XRD), scanning electric microscope (SEM), energy dispersive X-ray spectrometer (EDX) and Vickers hardness tester. Friction and wear behaviors of the coatings were tested without lubrication and the abrasion loss was measured after the friction test. The results showed that the MAO coatings, presenting rough and porous surface and high hardness, mainly consisted of α-Al2O3 and γ-Al2O3 phases. The composition of electrolytic solution had great influence on the coating morphology and its mechanical performance. Compared with the coating prepared in silicate and borate solutions, the coating prepared in aluminate solution had not only denser and smoother surface but also higher micro-hardness value and better abrasion resistance.