铝合金基体缺陷对其表面化学镀镍综合性能的影响

Effects of some defects of aluminum alloy substrate on properties of nickel coating electrolessly plated on it

以镀层外观、厚度、孔隙率、耐硝酸浸泡时间、耐中性盐雾性能及微观形貌为评价指标,探讨了铝合金基体来料存在腐蚀、“胶”(防腐剂残留物)、滚纹裂纹以及刀痕缺陷对化学镀镍综合性能的影响。结果表明,铝合金基体存在一定程度的腐蚀只会影响镀层外观,不影响其他性能;零件表面存在胶状物不仅影响镀层外观,而且造成漏镀,影响镀层综合性能;滚纹零件存在裂纹的话,镀层耐蚀性和孔隙率会受到影响;刀痕严重的零件施镀后,镀层的孔隙沿刀痕分布,耐蚀性不合格。

The effects of some defects of aluminum alloy substrate such as rusts,residues of corrosion inhibitor(a kind of adhesive matter),knurl cracks,and tool marks material on the properties of nickel coating plated electrolessly thereon were discussed by evaluating the coating appearance,thickness,porosity,endurability in nitric acid,resistance to neutral salt spray corrosion,and micromorphology comprehensively.The results showed that some rusts in the aluminum alloy substrate only affects the appearance of the nickel coatings but not their other properties.The existence of adhesive matters not only affects the appearance of the nickel coatings,but also causes skip plating,which has an adverse effect on their comprehensive performance.If there are cracks in the knurls,the nickel coatings have poor corrosion resistance and high porosity.For the parts with serious tool marks,pores tend to be formed and distributed along the tool marks,leading to the insufficient corrosion resistance of the nickel coatings.