含钙电解质对 Mg­1.0Ca 合金微弧氧化膜性能的影响

摘要

在含6 g/L 氢氧化钠和15 g/L 植酸钠的基本溶液中，分别加入4种钙盐研究钙盐，对 Mg­1.0Ca 合金微弧氧化膜性能影响。使用 SEM、EDS 和 XRD 分析陶瓷氧化膜的表面形貌、成分及结构，通过点滴实验和动电位极化曲线来判定氧化膜的腐蚀降解速率。结果表明：CaCO3可稍微增加氧化膜的钙含量，使氧化膜厚度由3.4μm 增加到8.8μm，且明显改善表面微孔均匀性。点滴实验和动电位极化曲线分析表明：CaCO3能显著提高氧化膜的耐蚀性能，其点滴时间由75 s 提高至116 s，自腐蚀电流密度由3.898μA/cm2降低至1.473μA/cm2，且自腐蚀电位由−1.538 V 升高至−1.465 V。%Four kinds of calcium salts were separately added into a base solution of 6 g/L NaOH and 15 g/L sodium phytate, and their influences on the property of anodic coatings formed on Mg­1.0Ca alloys were investigated. The surface morphologies, chemical compositions and structures were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X­ray diffractometry (XRD). The dropping test and potentiodynamic polarization tests were applied to evaluate the corrosion degradation rate of anodic coatings. The results demonstrate that CaCO3 can slightly increase the calcium content. The coating thickness increases from 3.4 μm to 8.8 μm and the coating porous uniformity of anodic coatings is obviously improved. The dropping test and potentiodynamic polarization curve analysis shows that CaCO3 can significantly improve corrosion resistance of the anodic coatings. The drop time is extended from 75 s to 116 s, and the self­corrosion current density is reduced from 3.898 μA/cm2 to 1.473 μA/cm2,while the corrosion potential is improved from −1.538 V to −1.465 V.