镁合金表面化学镀Ni-Co-P合金的研究

Process for Electroless Ni-Co-P Plating of Magnesium Alloy and Properties of the Coating

通过优化正交试验法研究了镁合金表面化学镀Ni-Co-P合金工艺。讨论了几种因素对沉积速度的影响。采用显微硬度测试、扫描电镜(SEM)、X射线能谱分析手段比较研究了Ni-Co-P与Ni-P镀层性能及化学成分。结果表明,Co2+的加入有利于化学镀层的沉积,但使镀层硬度下降;配位剂采用30 g/L柠檬酸钠时沉积速率最快;适量的香豆素可以提高镀速并使镀层更光亮。Ni-Co-P镀层表面较Ni-P镀层具有较好的耐腐蚀性能,结合力良好。

Orthogonal tests were carried out to optimize the process for electroless plating of Ni-Co-P alloy coating on the surface of magnesium alloy, and several factors affecting the plating rate were discussed. Moreover, the properties and chemical composition of the ternary alloy coating were compared to that of electroless Ni-P coating based on measurement of hardness and scanning electron microscopic and energy dispersive spectrometric analyses. It was found that the introduction of Co2+ was beneficial to the electroless plating of the ternary alloy coating but leadsed to decrease in the hardness of the coating. The highest plating rate was recorded at a concentration of 30 g/L of complexing agent sodium citrate, while the introduction of a proper amount of coumarin contributed to increasing the plating rate and improving the brightness of the coating. Moreover, the ternary alloy coating showed better corrosion resistance and adhesion to substrate than the Ni-P binary alloy coating.