Effect of Luminous Intensity on Open-Circuit Potentials for SUS 304 Stainless Steel in Natural Sea Water

摘要

It has been well known that the activity of microorganisms in corrosive environment has responsibility for an acceleration of corrosion rate of metallic materials. Therefore, the factors such as illuminous intensity which affects the degree of microorganisms activity can be thought to be associated with corrosion behavior of metallic materials. In this study, the effect of illumination on open-circuit potential (E_(OCP)) of SUS 304 stainless steel in natural sea water was investigated. Experimental results showed that E_(OCP) became ennobled with a decrease in illumination, and the response of E_(OCP) to illumination changes was rather rapid. The maximum range of E_(OCP) change was about 200 mV with the illumination varying between 0 lx (dark) and 18000 lx. In addition, it was found that the cathodic current on Pt electrode at 0 V vs. SSE in natural sea water raised with an increase in illumination. Perturbations of E_(OCP) and cathodic current with the luminous intensity were observed at the earliest stage of marine biofilm formation on the surface. It was suggested that the differences in luminous intensity on the stainless steel enhanced the possibility of localized corrosion in natural sea water.