化学镀镍层缓蚀工艺研究

目的提高化学镀Ni-P镀层的耐蚀性能。方法在钢铁基体表面化学镀Ni-P镀层,采用植酸、硅酸钠、钼酸铵和双氧水中的一种或多种复配对镀层进行钝化处理。通过硝酸点滴法、贴滤纸法分析镀层耐蚀性的变化,并通过正交实验确定四种物质复配的最佳浓度。结果以植酸、硅酸钠、钼酸铵和双氧水为主要成分配制的复合缓蚀剂能使镀层耐硝酸效果良好,电化学实验表明,复合钝化膜的腐蚀电流密度降低和阻抗值增加都超过1个数量级。结论所研究的复合缓蚀剂各组分间存在协同效应,最佳配方为:6 g/L植酸,6 g/L硅酸钠,4 g/L钼酸铵,30 mL/L双氧水。

Study on Corrosion Inhibition Process of Electroless Nickel Coating

Objective To improve the corrosion resistance of electroless Ni-P coating. Methods Passivation treatment for corrosion inhibition was conducted with phytic acid, sodium silicate, ammonium molybdate and hydrogen peroxide on the electroless NiP coating prepared on the steel substrate. The variation of corrosion resistance was investigated by dropping test and filter paper method. The optimal compositions of passivation solution were obtained by orthogonal experiments. Results The results showed that the complex inhibitor solution composed of phytic acid, sodium silicate, ammonium molybdate and hydrogen peroxide had good corrosion resistance in nitric acid dropping test. The electrochemical test showed that the corrosion current density of the composite passivation coating decreased and the impedance values increased by more than one order of magnitude. Conclusion The synergistic effect among the components in the passivation solution was observed. The optimized compositions of passivation solution were 6 cg/L of phytic acid, 6 g/L of sodium silicate, 4 g/L of ammonium molybdate, and 30 mL/L of hydrogen peroxide.