Mott-Schottky analysis of passive films on Cu containing Fe-20Cr-xCu (x=0, 4) alloys

Abstract

Effect of copper on the defect density of Fe-20Cr-xCu (x=0, 4) stainless steel alloys was investigated in deaerated pH 8.5 borate buffer solution at room temperature using Mott-Schottky analysis. Mott-Schottky analysis revealed that the addition of copper increased the acceptor density (N-A, V-Cr(-3)), i.e. decreased the Cr+3 content of the passive film. Also the donor densities, shallow donor (N-D1, V-cr(-3)) and deep donor (N-D2, V-Cr(+6)), of the passive films formed were increased. XPS analysis confirmed the decrease in Cr content and enrichment of copper in the passive film of Cu containing alloys, which ultimately dictated their lower corrosion resistance, i.e. decreased film protectiveness and stability.