基底表面质量对ZK60镁合金镀镍层性能的影响

Effect of Substrate Surface Quality on Nickel Plating Property of ZK60 Magnesium Alloy

摘要:

镁合金表面镀镍被广泛运用于镁合金工件防腐,而镀层的起泡和脱落严重影响工件的使用寿命。本文以ZK60镁合金为对象,研究了不同工件基底表面质量对镀镍层的影响机制。研究表明：基底表面存在的划痕和点蚀坑会显著降低镀镍层质量,引起镀层的起泡和脱落。基底表面的划痕会被保留到镀镍层中,引发镀层变薄,应力集中等问题,增加镀层开裂的几率。点蚀坑中的杂质与镁基底有不同的电化学特性,会导致镀层减薄和结合不牢。因此,提高镁合金工件基底表面光洁度、清除基底表面点蚀坑是提高镁合金镀镍层性能的必要措施。

Abstract:

Nickel plating on the surface of magnesium alloy is widely used in the anti-corrosion of magnesium alloy workpiece, but blistering and peeling from nickel plating will seriously affect service life of the workpiece. In this paper, effects of the different substrate surfaces on nickel plating properties of ZK60 magnesium alloy were studied. The results showed that the surface scratch and corrosive pitting significantly reduced the coating quality and caused blistering and peeling from nickel plating. The surface scratch of the substrate was retained under the nickel plating layer, which made the coating thinner, and caused stress concentration in the coating, and increased the probability of coating cracking. Differences in electrochemical properties between impurities in pitting pits and magnesium substrate led to thinning of the coating and weakened the adhesion of the coating. Therefore, good substrate surface finish and no substrate surface corrosive pitting are the guarantee of high quality nickel plating of magnesium alloy workpiece.