镁合金AZ31无铬无氟无亚硝酸盐磷化膜的制备及耐蚀性能

摘要

A phosphate solution free of chromate,fluoride and nitrite was prepared and an environment-friendly film was obtained on AZ31 magnesium alloy surface via the chemical deposition method.The morphology,composition,phase structure and its corrosion resistance were studied.The effects of film-forming temperature and free acid on corrosion resistance,microstructure and electrochemical behavior of the film were discussed.The results indicate that the corrosion resistance of AZ31 with the phosphate film was better than blank AZ31 substrate,which was most attributed to the great inhibitive action on the anodic dissolution and cathodic hydrogen evolution of the film.%以磷酸二氢锰和无氟、无铬、无亚硝酸盐的添加剂为主要成分,通过化学沉积的方法在镁合金AZ31表面获得致密均匀的耐蚀磷化膜.通过硫酸铜点蚀测试、SEM、XRD及电化学极化曲线等表征手段,详细研究了膜层的形貌、组成、相结构及耐蚀性能,讨论了成膜温度和游离酸对膜层微结构、形貌及耐蚀性能的影响.结果表明,磷化膜通过抑制阳极溶解和阴极析氢,有效地提高了镁合金AZ31的耐蚀性能.