目的 研究铝合金表面非铬酸盐高耐蚀性转化膜的制备工艺。 方法 以 K2ZrF6 和 K2TiF6 为主盐,KMnO4 为氧化剂,NaF 为成膜促进剂,在 5052 铝合金表面制备化学转化膜。 采用 SEM,EDS,FT-IR,XPS 对转化膜的形貌、结构以及成分进行分析,通过硫酸铜点滴实验、全浸蚀实验和极化曲线对转化膜的耐蚀性进行研究。 结果 获得了土黄色转化膜,主要由 AlF3·3H2O,AlOx / Al,Al2O3,MnO2 和 TiO2 组成。转化处理后,铝合金的腐蚀电位正移了约 591 mV,腐蚀电流密度由 1. 10 μA/ cm2 降低为 0. 48 μA/ cm2。经过封闭处理后,腐蚀电流密度降低为 0. 04 μA/ cm2,耐蚀性明显提高。 结论 以 K2ZrF6 和 K2TiF6 为主盐在铝合金表面形成的土黄色化学转化膜具有良好的耐蚀性。

Objective To study the preparation process of the chromate-free conversion treatment on aluminum alloys. Methods The chemical conversion coating was prepared with K2ZrF6 and K2TiF6 as the main salt, KMnO4 as the oxidant and NaF as the accelerant. The surface morphology, structure and composition were analyzed by SEM, EDS, FT-IR, and XPS. The corrosion resistance of conversion coating was studied by copper sulfate dropping, salt water immersion and polarization curve. Results The prepared yellow conversion coating mainly consisted of AlF3·3H2O, AlOx / Al, Al2O3, MnO2, and TiO2. The corrosion potential of the Al alloy sample was positively shifted about 591 mV and the corrosion current density was dropped from 1. 10 μA/ cm2 to 0. 48 μA/ cm2 after conversion treatment. After sealing treatment, the corrosion current density further decreased to 0. 04 μA/ cm2 and the corrosion resistance was significantly improved. Conclusion The conversion coating, which was prepared with K2ZrF6 and K2TiF6 as the main salt, had good corrosion resistance.