镁合金硫酸镍体系化学镀镍工艺及镀层性能研究

采用酸性钼酸盐酸洗、碱性钼酸盐活化工艺,研究了AM60镁合金上硫酸镍溶液体系化学镀镍的方法.采用扫描电子显微镜(SEM)观察镀层表面形貌,电子探针(EDX)分析镀层成分,电化学方法研究镀层腐蚀性能,锉刀试验测试镀层与基体结合力.结果表明,所得镀层为Ni-P合金镀层,磷质量分数为10%～14%;镀层均匀致密,无明显缺陷;镀层的自腐蚀电位接近-0.4 V(vs SCE),阳极极化曲线有明显的钝化区;Ni-P镀层耐蚀性好,与基体结合牢固.

Process for Electroless Nickel Plating of AM60 Magnesium Alloy in Nickel Sulfate Bath and Properties of the Coating

The process for electroless nickel plating of AM60 magnesium alloy in a nickel sulfate bath, based on etching in acidic molybdate and activation in alkali molybdate,was studied. The morphology of the resulting electroless Ni - P coating was observed using a scanning electron microscope, while its composition was analyzed by means of energy dispersive spectroscopy. Moreover, the adhesion of the Ni - P coating to the Mg alloy substrate was measured using file test, and the corrosion resistance of the Ni - P coating was evaluated by measuring the open - circuit - potential versus time curve and potentiodynamic polarization curve using electrochemical method. It was found that the electroless Ni - P coating was uniform and compact and had no obvious defects on the surface, with the content of P ( mass fraction) to be about 10% - 14%. The corrosion potential of the electroless Ni-P coating in the solution of 3.5%NaCl was about -0.4 V (vs SCE), and the anodic polarization curve showed evidences to the existence of a passivation region. Besides, the electroless Ni - P coating was well adhered to the Mg alloy substrate and had good corrosion resistance.