锌-镍合金三价铬钝化工艺的研究

Study on Trivalent Chromium Passivation Technology of Zn-Ni Alloy

研究了三价铬钝化液的pH值对锌-镍合金钝化膜的形成机理、耐蚀性、表面形貌的影响。在三价铬钝化过程中,pH值是一个重要的工艺参数,它决定了钝化膜的生成和溶解。当钝化液的pH值过低时,钝化膜的溶解速率过快,使得钝化膜的微裂纹结构不太明显,不利于提高钝化膜的耐蚀性。当钝化液的pH值过高时,钝化液的活性下降,锌的溶解速率降低,影响钝化膜的生长,同样不利于提高钝化膜的耐蚀性。在pH值为2.0的条件下制得的钝化膜具有均匀、致密的微裂纹结构,耐蚀性良好。

Influence of the pH value of trivalent chromium passivation solution on the formation mechanism, corrosion resistance and surface morphology of Zn-Ni alloy passivation film was investigated. It was found that, pH value was a significant parameter during trivalent chromium passivation process, which contributed directly to the formation and dissolution of passivation film. Lower pH value induced to dissolve the passivation film and decrease micro crack structures which were not benefit to improve the corrosion resistance of passivation film. However, higher pH value tended to decrease the activity of passivation solution and the dissolution rate of zinc, which affect the formation of passivation film, and were also not benefit to improve the corrosion resistance of passivation film. When pH value was 2.0, the prepared passivation film featuring dense and uniform micro crack structure, and has excellent corrosion resistance.