Development of High Speed Black Electroplating Process

Abstract

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.