Synthesis and performance of Zn–Ni–P thin films

• Published in: Chinese physics B 2015-03, Vol.24 (3), p.259-268
• Main Authors: Soare, V., Burada, M., Constantin, I., Ghita, M., Constantin, V., Miculescu, F., Popescu, A. M.
• Format: Article
• Language: English
• Subjects: Adhesion; Alloys; CNI; Coating; Concentration (composition); Deposition; EDTA; Sulfates; Thin films; X射线光电子能谱; Zinc; 合成; 最佳实验条件; 沉积参数; 薄膜样品
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/24/3/036101

The electroplating of Zn–Ni–P thin film alloys from a sulfate bath containing phosphoric and phosphorous acid was investigated. The bath composition and the deposition parameters were optimized through Hull cell experiments, and the optimum experimental conditions were determined（p H = 2, temperature = 298–313 K, zinc sulfate concentration =30 g·L^-1, EDTA concentration = 15 g·L^-1, and current density = 1.0–2.0 A·dm^-2）. The SEM analysis of the coating deposited from the optimum bath revealed fine-grained deposits of the alloy in the presence of EDTA. Optical microscopy analysis indicated an electrodeposited thin film with uniform thickness and good adhesion to the steel substrate. The good adherence of the coatings was also demonstrated by the scratch tests that were performed, with a maximum determined value of 25 N for the critical load. Corrosion resistance tests revealed good protection of the steel substrate by the obtained Zn–Ni–P coatings, with values up to 85.89% for samples with Ni contents higher than 76%. The surface analysis of the thin film samples before and after corrosion was performed by X-ray photoelectron spectroscopy（XPS）.