The Electrochemical Corrosion Behavior of Nanocrystalline 304 Stainless Steel Prepared by Magnetron Sputtering

Abstract

The electrochemical corrosion behavior of magnetron sputtered nanocrystalline (NC) 304 stainless steel (ss) thin film as well as that of the conventional rolled coarse crystalline (CC) 304ss has been studied in 0.05 M H₂SO₄ + 0.2 M NaCl solution using electrochemical and imaging techniques. The experimental results indicate that the NC thin film exhibits superior corrosion resistance compared to CC 304ss. The semi-conductor properties of the passive films on both materials as predicted by the Mott-Schottky equation show that the donor and acceptor concentrations of the passive film on NC thin film are higher than that of CC 304ss, while diffusion coefficients of carriers are lower than for CC 304ss. The composition of the passive film on NC thin film measured by X-ray photoelectron spectroscopy (XPS) has a higher the ratio of Cr oxides to Fe oxides. In-situ AFM observation found that the growth rate of the passive film on NC thin film was significantly faster than that of CC 304ss. The higher content of Cr oxides and better passivation ability of the passive film enhance the corrosion resistance of the nanocrystalline specimen together.