Corrosion behaviour of SUS304 stainless steel after UV–O 3 treatment in sealed air environment

Abstract

Ultraviolet ozone (UV–O₃) treatment was carried out on SUS304 stainless steel in a sealed chamber and polarisation curves on the steel were measured. The surface composition and the surface structure of the specimen following UV–O₃ treatment and polarisation were discussed. As a result, the corrosion resistance of SUS304 stainless steel could be enhanced by UV–O₃ treatment in a sealed chamber for short treatment times. However, longer illumination times of more than 14·4 or 21·6 ks did not additionally enhance the corrosion resistance. In addition, cyclic illumination with replenishment of air in the sealed chamber was helpful for improving corrosion resistance. The composition of the film on the steel surface changed after UV–O₃ treatment, namely, chromium and carbon decreased considerably, oxygen increased slightly and iron increased considerably. This demonstrated that increased iron oxide and decreased chromium oxide affected the corrosion resistance of the steel.