AZ31镁合金无氰化学镀镍工艺的研究

Process of cyanide-free electroless nickel plating on AZ31 magnesium alloys

研究了在AZ31镁合金表面二次浸锌后直接进行化学镀镍的工艺。分析了pH、温度、镍离子质量浓度和次磷酸钠质量浓度对镀速的影响,并测试了镀层的结合力、表面形貌、成分含量和耐蚀性。结果表明,以二次浸锌法进行预处理,无需氰化镀铜打底;在pH为7,碱式碳酸镍质量浓度25g/L,次磷酸钠质量浓度30g/L时,镀速有最大值;AZ31镁合金化学镀镍后耐蚀性明显提高,腐蚀电位从-1.52V提高到-0.55V;化学镀镍的优化参数为15g/L碱式碳酸镍,25g/L次磷酸钠,pH为6,温度82℃。

The electroiess nickel plating process on magnesium alloy AZ31 after the pre - treatment of double zinc dip process was studied. The influences of pH, temperature, concentration of basic nickel carbonate and sodium hypophosphite on deposition rate were analysed. The adhesion, surface morphology, content of various compositions and corrosion resistance of deposit were tested. The results show that the double zine dip process does not need cyanide copper plating for bottom plate ; when the pH is 7, the concentration of basic nickel carbonate is 25 g/L and sodium hypophosphite 30 g/L, the deposition rate reaches the maximum value; the corrosion resistance of magnesium alloys AZ31 is improved remarkably, and the corrosion potential is in creased to -0.55 V from - 1.52 V. The optimal process parameters are as follows： 15 g/L basic nickel carbonate, 25 g/L sodium hypophosphite, pH 6, temperature 82 ℃.