镍钴合金电沉积中硫酸钴影响的探讨

电沉积镍层硬度低,耐磨性差,在瓦特型镀镍液中加入硫酸钴可以提高镀层的抗热性能、耐蚀性能和韧性.采用硫酸盐电解液电沉积镍钴合金,研究了电解液中硫酸钴浓度与镀液分散能力、深镀能力的关系及其对镀层显微硬度、孔隙率和内应力的影响.同时,利用扫描电子显微镜分析了沉积层的表面形貌.结果表明:随着镀液中硫酸钴浓度的增大,镀液的分散能力下降,深镀能力升高;镀层显微硬度显著提高,内应力和孔隙率也有所增加.镍钴合金沉积层比纯镍镀层更细致、结晶均匀.

Effects of Cobalt Sulfate Concentration on Plating Bath Performance and Coating Properties of Nickel-Cobalt Electrodeposition

Ni-Co alloy coatings were electrodeposited in the sulfate bath containing various concentrations of cobalt sulfate. The relationship between the throwing power and covering power of the electrolyte and the concentration of cobalt sulfate was studied. The effect of cobalt sulfate on the microhardness, porosity, and internal stress of the Ni-Co deposits were also investigated. And the microscopic morphologies of the deposits were examined using a scanning electron microscope. It was found that the throwing power of the electrolyte slightly decreased with increasing concentration of cobalt sulfate in the electrolyte, while the covering power increased slightly therewith. The microhardness of the Ni-Co alloy coating greatly increased with increasing concentration of cobalt sulfate in the electrolyte, while the porosity and internal stress of the Ni-Co alloy coatings increased to some extent with increasing concentration of cobalt sulfate as well. Moreover, the nickel-cobalt alloy deposits were composed of smaller and more uniformly distributed grains as compared to pure nickel deposit.