S-羧乙基异硫脲鎓盐对化学镀镍的影响

摘要

研究了不同浓度的 S-羧乙基异硫脲鎓盐(ATPN)对酸性化学镀镍的沉积速率和镀层表面形貌的影响，通过极化曲线研究了化学镍的阴、阳极过程。结果表明，ATPN 能使镀层表面结晶细致。在ATPN的添加量小于11 mg/L时，ATPN 通过其分子中的S原子的电子效应，降低次磷酸根在镍表面的吸附能，因此随着ATPN的增加，次磷酸钠氧化加快，化学镀镍沉积速率加快。当ATPN添加量超过11 mg/L后，ATPN与镍形成很稳定的表面吸附配合物，减少了次磷酸钠在镍表面的吸附，因此随ATPN添加，次磷酸钠氧化受到抑制，沉积速率变小。当镍表面被ATPN完全覆盖，则会发生停镀或者不起镀。适宜的ATPN添加量为8~13 mg/L。%The effects of different concentrations of S-carboxyethylisothiuronium betaine (ATPN) on deposition rate of acidic electroless nickel plating and surface morphology of the Ni–P coating obtained were discussed. The anodic and cathodic courses of electroless nickel plating were studied by polarization curve measurement. The results indicated that the addition of ATPN can refine grains. When the amount of ATPN is less than 11 mg/L, the oxidation rate of hypophosphite is increased with increasing ATPN amount due to the fact that ATPN reduces the adsorption energy of hypophosphite on the surface of nickel by the electronic effect of atom S in the ATPN molecule, leading to an increased deposition rate of nickel. When the amount of ATPN is over 11 mg/L, the oxidation of hypophosphite is inhibited and the deposition rate is decreased due to the formation of a very stable adsorption compound of ATPN and nickel on nickel surface, reducing the adsorption of hypophosphite. When the surface of nickel is completely covered by ATPN, the electroless deposition of nickel is stop.The suitable dosage of ATPN is 8-13 mg/L.