镀液组成对黄铜表面中温化学镀Ni-P合金的影响

Effects of Bath Composition on Electroless Ni-P Plating onto Brass Surface at Medium Temperature

以硫酸镍为主盐,次磷酸钠为还原剂,乳酸+冰乙酸为复合络合剂,硫酸铵为加速剂,在酸性、中温(70℃)条件下,采用化学镀法在黄铜表面镀覆Ni-P合金镀层,并研究了主盐与还原剂的配比、络合剂和加速剂的用量对化学镀的影响规律,确定了镀液的最优配方。结果表明:硫酸镍与次磷酸钠的配比对沉积速率和镀层显微硬度均有较大的影响;复合络合剂中的乳酸主要起络合剂的作用,冰乙酸主要起缓冲剂的作用;添加硫酸铵可增加次磷酸根的活性,使沉积速率增大。

A electroless Ni-P plating was obtained on brass surface at medium temperature （70 ℃） in acidic nickel plating system by using nickel sulfate as main salt, sodium hypophosphite as reducing agent, lactic acid and glacial acetic acid as composite complexing agent and ammonium sulphate as accelerating agent. The effects of ratio of main salt and reducing a- gent, amount of complexing agent and accelerating agent on electroless plating were investigated. The optimal formula of bath was determined. The results show that the ratio of nickel sulfate and sodium hypophosphite significantly influence on deposition rate and hardness. In the composite complexing agent, actic acid mainly plays the role of complexing agent, where as glacial acetic acid mainly plays the role of buffer. Hypophosphite activity is enhanced by ammonium sulfate, which increases the deposition rate.