锌盐及抑制剂对铝合金无氰浸锌层组成及形貌的影响

Effects of Zincates and Inhibitors on Composition and Mor-phology of Cyanide-Free Dipped Zinc Coating on Aluminum Alloy

为了探明铝合金上无氰浸锌层的组成及其形貌,采用扫描电镜、X射线能谱仪对镀层进行了分析,研究了基础液中添加不同锌盐、配位剂和抑制剂对浸锌过程、稳定电位和置换层结晶形貌的影响。获得了优化的无氰浸锌配方:80.0 g/L NaOH,12.5 g/L NiCl2,0.6 g/L CuSO4,0.8 g/L FeCl3,25.0 g/L Zn(NO3)2,1.0 g/L NaNO3,12.5 g/L葡萄糖酸钠,0.2 g/L抑制剂乙撑硫脲。结果表明:使用硝酸锌的浸锌效果最好,锌膜薄、细致均匀;抑制剂有效地降低了浸锌层中含锌量,使结晶细化;硝酸锌与配位剂、抑制剂配合使用时浸锌效果最佳,所得镀层附着性能良好。

A scanning electron microscope and an energy dispersive X-ray analyzer were per-formed to investigate the composition and morphology of cyanide -free zincate coating on Al alloy. The effects of ZnO, ZnS04 and other zincates containing different anions as well as inhibitors on the zincate dipping process, steady potential and morphology of dipped Zn coating were studied in detail. Results show that Zn(NO3)2 was more effective than other zincates for preparing thin and uniform Zn coating. The inhibitors were able to reduce the Zn content of Zn coating effectively, leading to the formation of a thin zincate layer. When Zn( NO3) 2 , complexing agents and inhibitors were used together, the zincating process could be ac-complished at a best efficiency and the resulting Zn coating had good adhesion to Al alloy substrate.