铝合金表面聚天冬氨酸改性锆转化膜

Polyaspartic acid-modified zirconium conversion coating on aluminum alloys

常温下采用化学浸渍法在1070铝合金表面获得了锆-聚天冬氨酸复合转化膜（复合膜）。通过电化学阻抗谱和中性盐雾试验考察了膜层的耐蚀性。采用扫描电镜、能谱仪和X射线光电子能谱仪分析了膜层的形貌、结构和化学组成。结果表明，在由0.1-0.3g/L硼酸、0.1-0.5班氟硼酸和0.5-1.0g/L，L组成的氟锆酸锆转化液中加入0．5-1.0g／L聚天冬氨酸钠，所得复合膜较未加聚天冬氨酸钠时更致密，耐蚀性更好。涂覆上某市售环氧粉末涂料后，所得涂层的综合性能更好。探讨了复合膜的成膜机理。

A zirconium-polyaspartic acid composite conversion coating （called as composite coating） was prepared on the surface of 1070 aluminum alloy by chemical immersion at room temperature. The corrosion resistance of the coating was studied by electrochemical impedance spectroscopy and neutral salt spray test. Its morphology, microstructure and chemical composition were analyzed by scanning electron microscope, energy-dispersive spectroscope and X-ray photoelectron spectroscope. The results showed that in comparison with the zirconium conversion coating obtained from a zirconium conversion bath comprising boric acid 0.1-0.3 g/L, fluoroboric acid 0.1-0.5 g/L and hexafluorozirconic acid 0.5-1.0 g/L, the composite coating obtained from the zirconium conversion bath added with 0.5-1.0 g/L sodium polyaspartate is more uniform and compact, and has better corrosion resistance, on which a commercial epoxy powder coating has better comprehensive performance. The formation mechanism of the composite coating was discussed.