C3H8O3含量对AZ91D镁合金微弧氧化过程及膜层特性的影响

在含有不同C₃H₈O₃含量的硅铝复合电解液中，利用交流脉冲电源在AZ91D镁合金基体上制备了一系列微弧氧化膜。利用SEM和膜层测厚仪分别研究了陶瓷膜层的微观形貌特征及厚度，采用全浸泡实验和电化学阻抗谱测试了膜层在3.5%NaCl中性溶液中的耐蚀性能。结果表明，微弧氧化过程中的起弧电压和终止电压均随C₃H₈O₃含量的增加而呈上升的变化趋势。随着C₃H₈O₃含量的增加，膜层耐蚀性先提高后降低，而膜厚变化幅度不大。膜层的耐蚀性主要取决于内部致密层，当C₃H₈O₃含量为5 mL/L时，膜层相对较致密，因而表现出良好的耐蚀性能。

Influences of C3H8O3 Concentration on Formation and Characteristics of MAO Coatings on AZ91D Magnesium Alloy

Microarc oxidation (MAO) coatings were obtained on the AZ91D magnesium alloy by AC pulse electrical source in a silicate-aluminate based composite electrolyte containing various concentrations of C₃H₈O₃. The morphologies and thickness of ceramic coatings were characterized by SEM and layer thickness meter, respectively. The corrosion resistance of coatings in a 3.5%NaCl neutral solution was evaluated by the immersion test and electrochemical impedance spectroscopy (EIS). The results showed that the striking voltage and final voltage increased gradually with the increase of C₃H₈O₃ concentration during the MAO process. With the increase of C₃H₈O₃ concentration in the electrolyte, the corrosion resistance of the coatings increased at first and then decreased gradually, however, the variation of the coating thickness was not obvious. The EIS results showed that the corrosion resistance of the coatings was influenced by the inner dense layer. The coating exhibited better corrosion resistance in the electrolyte containing 5 mL/L C₃H₈O₃ due to its relatively compact microstructure.