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采用析氢实验及Tafel极化曲线研究了AZ31B镁合金在不同pH植酸溶液中成膜时的反应速率和转化膜的防腐性能,并用SEM,AFM,EDS.FTIR观察和检定转化膜形貌、元素组成及官能团构成.结果表明溶液的pH=1时,植酸与镁合金的反应剧烈,转化膜有大量的裂纹;pH=4和pH=6时.反应速率很慢,成膜均匀并较少裂纹,但转化膜较薄;pH=2时,反应速率较为和缓.转化膜表面较为平整.有呈网格状结构的大量细小裂纹.此时,所形成的植酸转化膜具有最佳的防腐性能.此外.植酸转化膜由较薄的内层及具有一定裂纹的外层所组成,转化膜含有Mg.Al,zn,C.O.P元素及PO_4~-3,HPO_4~2-.OH~-基团.
Hydrogen evolution experiments and Tafel polarization curves were used to study the reaction rate and the corrosion resistance of the AZ31B magnesium alloy during the film formation in different pH phytic acid solutions. The morphologies of the conversion films were observed and determined by SEM, AFM and EDS. Composition and functional group.The results show that the reaction between phytic acid and magnesium alloy is violent when the solution pH = 1, there are a lot of cracks in the conversion coating.For pH = 4 and pH = 6, the reaction rate is very slow, the film formation is even and less Cracks, but the conversion film is thin; pH = 2, the reaction rate is more moderate. Conversion film surface is relatively smooth. There are a large number of small cracks were grid-like structure. At this time, the formation of phytic acid conversion coating has the best anti-corrosion In addition, the phytic acid conversion coating consists of a thinner inner layer and an outer layer with a certain crack. The conversion coating contains Mg.Al, Zn, COP elements and PO_4 ~ 3, HPO_4 ~ 2 ~ .OH ~ - group.