Development of High Speed Black Electroplating Process

High speed black electroplating process was developed. The black coatings are deposited on cathode surface by electrolysis in acid solution containing Zn2+, Ni2+, Cr3+ and No3-. Quantity of electricity to obtain the black surface is only 2×103 C/m2.The black coatings are mainly composed of hydrated oxides, metallic Zn and Zn-Ni alloy.The blacked Zn-Ni alloy plated steel sheet with chromate and resin coat has excellent properties, for example, scratch resistance, corossion resistance and weldability.