The Preparation and Characterization of a Cyanide-Free Brush-Plating Solution for Application in the Electric Power Industry

Abstract

In this paper, a bright and compact silver coating on a copper sheet was successfully prepared by a coating solution without cyanogen. The effects of cerium nitrate (Ce(NO3)3) content on the structures, physicochemical properties, and application of the coating were thoroughly discussed with the help of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), mapping, X-ray diffraction (XRD) electrochemical workstation, and infrared thermometer. The results pointed out that the thickness of the silver coating could reach about 30 μm, with good adhesion to the copper substrate. Cerium nitrate was evenly distributed on the surface of the coating, which can effectively refine the crystal grains and enhance the corrosion resistance. When the dosage of cerium nitrate was 1.0 g/L, the crystal grains were decreased from 144 nm to 65 nm, and the corrosion voltage was increased from −0.238 V to −0.131 V, respectively. The silver plating layer showed the best corrosion resistance with the dosage of silver nitrate, sulfosalicylic acid, additive, cerium nitrate, ammonium acetate, polyethylene glycol 400, and the number of brush-plating operations were 10, 50, 55, 1, 10, 10 g/L, and 8 times, respectively. For application, the temperature of the transformer’s isolating switch could remarkably be decreased from 100 °C to 54 °C with brushing plating by the silver coating solution.