配位剂对黄铜中温化学镀Ni-P合金镀层的影响

Effects of Complexing Agent on Electroless Ni-P Plating onto Brass Surface at Medium Temperature

为解决传统高温化学镀鎳所存在的诸多问题,在中温(70℃)酸性条件下,以硫酸镍为主盐,次磷酸钠为还原剂,乙酸钠为缓冲剂,就乳酸、冰乙酸及二者复合的配位剂对黄铜中温化学镀Ni-P合金镀层性能的影响进行了研究。结果表明:复合配位剂中的乳酸主要起配位剂的作用,冰乙酸主要起缓冲剂的作用;采用复合配位剂的镀液的沉积速率与采用单一配位剂的镀液相当,但稳定性好,镀层孔隙率低,乳酸7.5 mL/L+冰乙酸13.0mL/L时所获得的镀层光亮平整,颗粒细小,均匀致密,且与基体结合良好,显微硬度可达515HV,孔隙率低于1cm-2,具有较好的耐磨性和耐蚀性。

To solve the problems of traditional high temperature electroless nickel plating process, the effect law of lactic acid, glacial acetic acid and composite complexing agent on eleetroless Ni-P plating on brass surface was studied by using nickel sulfate as main salt, sodium hypophosphite as reducing agent and sodium acetate as buffer agent in acidic nickel plating system at medium temperature（70 ℃ ）. The results show that, in the composite complexing agent, aetic acid mainly plays the role of complexing agent, where as glacial acetic acid mainly plays the role of buffer. Meanwhile, compared with single complexing agent,composite complexing agent has the same deposition rate, but its bath stability and porosity of plating is better. A bright, smooth plating with dense appearance and combined well with the brass surface could be obtained with actic acid of 7.5 mL/L and glacial acetic acid of 13 mL/L. The hardness of coating can reach 515HV and the porosity is lower than 1 cm 2, which exhibits coating had good abrasion resistance and corrosion resistance.