Crack-free hard chromium plating using pulse-reverse electroplating method on the brass substrate

초록

Electroplated chromium coating has been applied in many industrial applications owing to the high levels of hardness, wear and corrosion resistance. However, electroplated chromium coating layer possess a lot of cracks on surface due to internal stress, leading to low corrosion resistance. In this study, we proposed a pulse-reverse (PR) electroplating method to reduce crack and increase hardness on surface of the coated layer. Also, we compared surface properties between a PR electroplating and a direct current (DC) electroplating method. All samples were electroplated in a Sargent bath with HY-30 using DC and PR electroplating method. The morphology and crack density of coating were investigated by optical microscope (OM). The surface composition of samples was determined by X-ray photoelectron spectroscopy (XPS). The current efficiency was determined by measuring the weight difference between before and after electroplating. The thickness and hardness of coating layer were evaluated using X-ray fluorescence spectrometer (XRF) and nano indenter, respectively.