Factors Affecting the Stability of Mild Steel Under Anodic Conditions in Copper Cyanide Plating Baths

Abstract

SUMMARYPolarisation studies have been carried out on copper and steel anodes in copper cyanide electrolytes. It is shown that if the applied potential is low copper behaves as a normal soluble anode; the steel does not share in the anodic current and remains immune to electrochemical attack. At higher potentials the copper passivates and the steel carries most of the anodic current. Under these circumstances the steel may corrode by the formation of a cyanide complex. Increasing the alkalinity of the bath encourages the preferential discharge of hydroxyl ions and so serves to protect the steel.