铝合金表面无铬磷酸盐稀土转化膜的成膜机理及耐蚀性研究

Study on the Film Forming Mechanism and Corrosion Resistance of Non-chromium Phosphate Rare Earth Conversion Coating on Al Alloy

从磷化成膜过程的电化学行为和稀土对磷化膜生长过程的影响两方面,对6061铝合金表面一种不含铬的复合磷酸盐膜的成膜机理进行了研究,并利用极化曲线对其耐蚀性进行了初步探究。结果表明:磷化成膜过程主要分为4个阶段,即基体侵蚀期、晶体初步形成期、基体再溶解和晶体形成期、基体溶解和晶体生长达到平衡期;稀土化合物的引入,提高了磷化膜的耐蚀性,缩短了磷化时间,同时也促进了反应离子在金属表面的吸附,形成多个活性点,有利于新的结晶均匀增长,极大改善了磷化膜的表面质量。

The electrochemical behavior of film process and the effect of rare earth on a phosphating film＇s growth process were studied. The phosphating film was formed on 6061 aluminium alloy surface, it was non-chromium phosphate rare earth conversion coating. At the same time it＇s corrosion resistance was explored preliminarily by making use of the polarization curve. The results show that this bonderizing process has mainly four stages., this bonderizing process has mainly the basement corroding scheduled time, crystal first formation scheduled time, basement dissolve again and crystal formation scheduled time, basement dissolve and crystal growth equilibration scheduled time. With the help of rare earth, the corrosion-resistance of the bonderizing film is raised, and phosphating time is shortened, at the same time the reaction ion being in metal outside adsorption is boosted and many active point was formed. This is beneficial to the new crystal＇s incresament homogeneously. Therefore the bonderizing film surface mass is improved greatly.