无机盐对化学镀镍层耐蚀性的影响

摘要

The surface morphology of the electroless Ni-P alloy coating on the surface of A1 alloys, which was obtained in bath containing inorganic salt potassium iodide (KI), was investigated by metallurgical microscope, and the influence of KI on the corrosion resistance of Ni-P coating was studied by AC impedance. The results show that KI decreases the number of the surface defects of Ni-P coating, fines the crystal grains of the coating, making the coating more level and compact, thus the surface quality is improved. Besides, KI makes the charge transfer resistance in NaC1 solution greater so that the corrosion resistance of the coating is bettered.%通过金相显微镜考察了镀液中存在无机盐碘化钾(KI)时所得铝合金表面化学镀Ni-P层的表面形貌,采用交流阻抗研究了KI对Ni-P层耐蚀性的影响.结果表明:KI减少了Ni-P层中表面缺陷的数量,细化了镀层晶粒,镀层更加平整、致密,表面质量得到改善;另外,KI使镀层在NaCl溶液中的电荷转移电阻增大,提高了镀层的耐蚀性.