羧基配位剂对电镀镍–磷合金的影响

Influence of carboxyl complexant on nickel–phosphorous alloy plating

以羧基类物质作配位剂,在A3钢板表面电沉积制备Ni–P合金镀层。镀液基础组成和工艺参数为：NiSO4·6H2O 240 g/L,NiCl2·6H2O 45 g/L,NaH2PO2·H2O 50 g/L,H3BO3 35 g/L,NaF30 g/L,pH 2.0,温度70℃,电流密度2.5 A/dm2,时间20 min。研究了镀液中羧基配位剂含量对Ni–P镀层沉积速率和耐蚀性的影响。结果表明,随羧基配位剂含量增大,沉积速率减小,镀层耐蚀性先改善后变差。其适宜含量为20～30 g/L。羧基配位剂含量为25 g/L时,镀层外观光亮、结合力良好,耐蚀性和耐磨性优于未加配位剂的镀层。镀层的P含量为18.11%,属于高磷非晶态Ni–P镀层。羧基配位剂具有细化镀层晶粒的作用,使镀层表面更为平整、致密。

Ni-P alloy coatings were prepared by electrodeposition on the surface of A3 steel plate using carboxyl compound as complexant. The basic plating bath composition and process parameters are as follows： NiSO4·6H：O 240 g/L, NiCl2·6H2O 45 g/L, NaH2PO2·H2O 50 g/L, H3BO3 35 g/L, NaF 30 g/L, temperature 70 ℃, pH 2.0, current density 2.5 A/dm2, and time 20 min. The effect of carboxyl complexant content in plating bath on electrodeposition rate and corrosion resistance of Ni-P coating was studied. The results showed that the electrodeposition rate is decreased while the corrosion resistance of coating is improved initially and then deteriorated with the increasing of complexant content. The suitable content of complexant is 20-30 g/L. The coating prepared with 25 g/L carboxyl complexant is bright and well-adhered, and has better resistance to corrosion and abrasion than the coating obtained from a complexant-free plating bath. The NiP coating is amorphous and has high phosphorous content （18.11%）. The carboxyl complexant makes NiP alloy coating smoother and more compact due to its grain refinement effect.