中国科学院材料磨损与防护重点实验室/先进润滑与防护材料研究发展中心知识库

Although nickel has a lower standard electrode potential than copper, nickel-sulfur coatings were successfully deposited on copper through one-step immersion plating method, which was carried out in the aqueous solution consisting of NiSO₄·6H₂O and Na₂S₂O₃·5H₂O at room temperature. The open circuit potential tests demonstrated that copper had a more negative potential than nickel in Na₂S₂O₃·5H₂O solutions, which made the deposition of nickel on copper through immersion plating feasible. Because of the decomposition of sodium thiosulfate, sulfur could be codeposited with nickel and the nickel-sulfur coatings were finally obtained. The surface morphology and composition of the coatings were characterized with SEM, EDS, XPS and XRD analyses, and the results indicated the coatings were mainly composed of metallic nickel and Ni₃S₂. The deposition process of the nickelsulfur coatings was investigated by analyzing the morphology evolution of copper substrates. The as-prepared nickel-sulfur coatings possessed good anticorrosion ability for its compact structure and could lower the corrosion current density of copper in 3.5 wt% NaCl solution to its 1/20.