中文摘要：

分析了浸锌层的作用机理，利用恒电势下电流密度随时间的变化和开路电势随时间变化的曲线，研究了镍在浸锌层上的形成机理。研究发现：镍的电沉积形核过程为连续形核，超电势增加时，晶核数迅速增加；镍层的生长过程遵循Volmer-Weber模式；浸锌层能明显改善镀层结合力。在镀镍溶液中加入晶粒细化剂，细化了镀层晶粒，提高了镀层性能。X射线衍射表明：晶粒细化剂加入后，镍层晶粒明显细化，平均粒径约为26nm，镍层表现为（111）择优取向。纳米晶镍层具有优良的性能，15μm厚的镀层24h中性盐雾实验的保护等级为9级，热震和划痕试验表明结合力良好。

英文摘要：

The function mechanism of zinc immersion film was analyzed. The formation mechanism of zinc coating on magnesium alloys was investigated by using current clensity time and open potential-time curves at constant potential. It is found that the electrocrystallization of nickel on magnesium alloy is a successive nucleation process. With the increase of deposition overpotential, the crystal nucleus dots will increase rapidly. The growth of nickel coating obeys Volmer-Weber mode. Zinc immersion film can obviously improve adhesion between nickel coating and magnesium alloy. Grains of nickel coating are distinctly fined when crystal finer is added. XRD shows that grain size of the nickel coating is about 26 nm on average in diameter. The deposits are the microtexture in preferential （111） direction. The nickel coating has good adhesion and corrosion resistance. The protection grade of nickel coating reaches Grade 9 after 24 hours neutral salt spraying test and there are no peeling or blistering on the coating by thermal shock testing and scribe-grid testing.