In this paper, the formation process, morphology, and electrochemical performance of PEO coatings on AM50 magnesium alloy prepared in low concentration phosphate, aluminate, and phosphate-aluminate electrolytes were systematically studied. The results show that the coatings prepared from the phosphate electrolytes have a higher thickness and better corrosion resistance properties compared to the other electrolytes. The coatings prepared from low concentration phosphate-aluminate mixed electrolytes have slightly thinner thickness, a similar coating structure and an order of magnitude lower value of electrochemical impedance compared with phosphate electrolyte coatings. The Coatings prepared from low concentration aluminate electrolytes have the lowest thickness and the worst corrosion resistance properties which gets close to corrosion behavior of the bare AM50 under the same test conditions. Considering application, coatings prepared from single low concentration phosphate electrolytes and low concentration phosphate-aluminate electrolytes have greater potential than single low concentration aluminate coatings. However, reducing the electrolyte concentrations of coating forming ions too much has negative influence on the coating growth rate.

本文系统研究了在低浓度磷酸盐、铝酸盐和磷酸铝酸盐电解液中制备的AM50镁合金上PEO涂层的形成过程、形貌和电化学性能。结果表明，与其他电解液相比，磷酸盐电解液制备的镀层具有更高的厚度和更好的耐腐蚀性能。低浓度磷酸盐-铝酸盐混合电解质制备的涂层与磷酸盐电解质涂层相比，厚度稍薄，涂层结构相似，电化学阻抗值低一个数量级。低浓度铝酸盐电解液制备的镀层厚度最小，耐腐蚀性能最差，在相同测试条件下与裸AM50的腐蚀行为接近。从应用角度考虑，单一低浓度磷酸盐电解质和低浓度磷酸铝酸盐电解质制备的涂层比单一低浓度铝酸盐涂层具有更大的潜力。然而，过多降低涂层形成离子的电解质浓度会对涂层生长速率产生负面影响。