植酸改善镁合金锌系磷化膜耐蚀性的研究

A Research on Corrosion Resistance of Phytic Acid Improved Zinc Series Phosphating Coating on Magnesium Alloy

采用化学转化法在镁合金表面制备了磷酸盐转化膜。在基础磷化液中添加植酸,改善膜层的耐蚀性。通过交流阻抗、Tafel曲线和硫酸铜点滴实验确定了植酸最佳的质量分数为1.5%。该质量分数下的容抗弧半径最大,自腐蚀电流密度最低,耐蚀性最好。通过扫描电镜测试得出:膜层的表面结构为晶粒紧凑堆积状,该膜层很好地覆盖了基体表面,起到了一定的防护效果。

A phosphate conversion coating was prepared on magnesium alloy by chemical conversion method.Phytic acid was added to the phosphating solution for improving the corrosion resistance of the coating.The optimum mass fraction of phytic acid was determined as 1.5 ％ through AC impedance,Tafel curve and copper sulfate dropping experiments.Under this mass fraction,the capacitive reactance arc radius is the largest,the self-corrosion current density the lowest and the corrosion resistance the best.As shown in scanning electron microscope （SEM） test,the surface structure of the coating is of compactly stacked grains,and the film covers the substrate surface well,thus playing a certain protective effect.