高耐蚀性锌铁低磷三元合金电镀工艺的开发与研究 第二部分──低铬彩钝工艺及钝化液、钝化层的性能

Development and research of high-resistance low-phosphorus zinc-iron-phosphorus ternary alloy electroplating process—Part II.Low-chromium passivation process and properties of bath and coating

与锌铁低磷三元合金电镀3-艺相配套的低铬彩色钝化液主要由13g/LCr03、10g／L活化剂和适量含硅化合物组成。钝化膜封闭的工艺条件为：有机硅溶液20mL／L，甘油40mL／L，表面活性剂少许，pH3～5，室温，浸泡时间30s。采用扫描电镜和透射电镜分析了钝化膜的微观形貌。通过在5％（质量分数）NaCl溶液中的极化曲线测量以及中性盐雾试验，考察了钝化膜的耐蚀性。结果表明，含硅钝化膜耐80。C热水浸泡3min及耐120℃热冲击1h的性能优于常规钝化膜。加入稳定剂可使含硅钝化液存放4个月而不发生凝胶现象。封闭后，钝化膜的微裂纹中填充了纳米Sin，其憎水性明显提高。

The low-Cr iridescent passivation bath developed for low-phosphorus Zn-Fe-P ternary alloy electroplating is composed of CrO3 13 g/L, activating agent l0 g/L, and a certain amount of Si-containing compound. The process parameters for sealing the passivation films are as follows： silicone solution 20 mL/L, glycerin 40 mL/L, a small amount of surfactant, room temperature, pH 3-5, and immersion time 30 s. The morphologies of passivation films were analyzed by scanning and transmission electronmicroscopy. The corrosion resistance of passivation films was examined by polarization curve measurement in 5wt% NaC1 solution and neutral salt spray test. The results showed that the Si-containing passivation film has better resistance to immersion in 80 ~C water for 3 rain and to thermal shock at 120 ℃ for 1 h than a conventional passivation film. The Si-containing passivation bath with the addition of stabilizing agent was stable without gelation in 4 months. The hydrophobicity of passivation film is improved obviously by sealing due to the filling up of micro-cracks of the passivation film with nano SiO2.