Evaluation of atmospheric corrosion on metal by surface potential distribution measurement

When metal is exposed at the atmospheric environment, thin water film is formed on the metal surface. This film is strongly affected by environmental parameters such as temperature, relative humidity and rainfall. Because a film that consists of aqueous solution on a metallic surface is extremely thin, it is difficult to investigate the surface reaction by the conventional electrochemical technique. In this paper, a surface potential measurement device with non-contact probe was applied to measure the potential of the passive metals. The corrosion behavior of the materials surface was also investigated by using the surface potential. The surface potential distribution of high corrosion resistance materials showed different behavior between titanium and type 304 stainless steel (SUS304). The potential on the SUS304 became less noble during drying up. In the case of Ti, the potential didn't descend intensely. From these results, the determination of the surface potential using a surface potential measurement device is quite suitable to investigate the atmospheric corrosion behavior of high corrosion resistance materials.