Effect of adding Sr(OH)2 on the formation process of 2024 aluminum alloy micro-arc oxidation coatings

Micro-arc oxidation coatings with oxidation times of 15 S, 30 S, 60 S, 120 S, 240 S and 1800 S were prepared on 2024 aluminum alloy using silicate-phosphate electrolytes containing 0 g/L and 0.5 g/L Sr(OH)2, 2 , respectively. The effects of adding Sr(OH)2 2 on the oxidation voltage, surface morphology and phase composition of the 2024 aluminum alloy MAO coatings formation process were investigated using SEM, XRD and XPS. The results show that adding Sr(OH)2 2 increases and then decreases the oxidation voltage compared with that of the unadded Sr (OH)2, 2 , which has little effect on the morphology of the oxide coatings, the Sr2+ 2+ and PO3- 3- 4 in the solution are jointly involved in the formation of the MAO coatings. The main phase composition of the coating is gamma-Al2O3, 2 O 3 , and the Sr element is uniformly distributed as SrCO3 3 in the coating.