Evaluation of Corrosion Resistance Properties byApplying Galvanostatic Nanoscale Current Densityon Passive Metals

Abstract

In this study, new evaluation method for the stability and corrosion resistance properties of passive films has been suggested by means of observation of self-activation process in open-circuit state and galvanostatic nanoscale reduction test. The experiments were performed for air-formed oxide film in case of plain carbon steel, and for anodically passivated films formed in aqueous sulfuric acid solutions in case of titanium and 304 stainless steel. From these experimental results, we derived two parameters, i0 and q0, which characterize the self-activation process and the properties of passive film on a stainless steel surface. The parameter i0 was defined as the rate of self-activation, and q0, the reduced amount of charge during the self-activation process. In conclusion, it is considered that the stability and corrosion resistance of passive metals and alloys can be evaluated quantitatively by three parameters of τ0, q0, and i0, which easily obtain by means of observing the self-activation process and galvanostatic nanoscale reduction test.