Repassivation Studies of Some Mechanically Damaged Metal Surfaces

Abstract

Repassivation studies of four commonly used metals and alloys; iron, nickel, mild steel and stainless steel were carried out in 0.05M, 0.15M and 0.50M NaHC03 media at a pH of 8.3. The removal of the oxide film, under potentiostatic conditions was effected by means of a sapphire point mounted on a moving trolley attached to a perspex electrolytic cell. The resulting current time-transient was recorded on an oscilloscope and a strip chart recorder, and analysed to evaluate the kinetics of the repassivation process. The rate of removal of the passive film was 80+10 cm s-1. ...