A study on the Semiconducting Properties of Passive Films on Stainless Steels by Photo-Electrochemical Techniques

摘要

Semiconducting properties of the passive films on ferrite stainless steels were examined in a pH 7.8 buffer solution by photo-electrochemical techniques (Photocurrent measurements and Mott-Schottky analyses). By passivation of stainless steel in an aqueous mixture of nitric acid and hydrofluoric acid, surface morphology and composition were dramatically changed. Under unbiased UV-illumination, all passive films tested showed p-type photocurrent, while air formed oxide film showed n-type photocurrent in buffer solution. It was found that p-type photocurrent and stability of stainless steel was strongly dependent on Cr content.