以硫酸亚锡为主盐,通过化学转化法在铝合金表面形成耐蚀性良好的无铬化学转化膜.考察了锡盐浓度、成膜氧化剂浓度、成膜促进剂的质量浓度、反应温度及反应时间对膜层耐蚀性的影响,并对转化膜的耐蚀性能进行了电化学测试.在pH值为2～3时,确定了无铬化学转化液膜的最佳制备条件:SnSO4 0.15 g/L、KMnO4 1.5 g/L、NaF 2 g/L,反应温度30 ℃,反应时间1.5 min；该转化膜制备工艺简便、成膜速度快,膜的耐蚀性能好.

A chrome-free chemical conversion film with good corrosion resistance was prepared by chemical conversion method using stannous sulfate as main salt.Effects of stannous sulfate concentration,film-forming oxidant concentration,film-forming accelerator concentration,reaction temperature and reaction time on corrosion resistance of the coating were studied.Corrosion resistance of the conversion coating was examined by electrochemical testing.At pH 2～3,the optimal preparation technologic conditions of chrome-free chemical conversion film were SnSO4 0.15 g/L,KMnO4 1.5 g/L and NaF 2 g/L,reaction temperature 30 ℃,reaction time 1.5 min.The tin salt conversion film has simple preparation technology,rapid film-forming speed and good corrosion resistance.