A sensing plate for the simultaneous pH and Cl^－ concentration measurements was fabricated and used as a crevice former to visualize the pH and Cl^－ distributions inside the crevice of nitrogen-containing stainless steel （Fe18Cr-10Ni-5.4Mn-0.25N）. The initial morphology of the crevice corrosion of the nitrogen-containing stainless steel was a micro-pit. The initiation of the micro-pit led to a large decrease in pH and an increase in the Cl^－ concentration. The low pH and high Cl^－ concentration region expanded with crevice corrosion propagation. The initiation mechanism of the crevice corrosion of the nitrogen-containing stainless steel was quite similar to that of the nitrogen-free stainless steel （Fe-18Cr-10Ni-5.4Mn） reported in previous studies. An increase in pH and a decrease in the Cl^－ concentration were observed in the local repassivation area of the crevice corrosion.

This study focused on the corrosion progress of spheroidal graphite cast iron in the atmospheric environment. The carbon steel and weathering steel were tested as comparative targets through atmospheric exposure. The corrosion rate of spheroidal graphite cast iron in four years is smaller than that of carbon steel, whereas equal to or less than that of weathering steel. As a result of investigating the density and corrosion resistance of the rust layer formed during the atmospheric exposure test, the rust layer of spheroidal graphite cast iron tends to have electrochemically high protection compared to carbon steel and weathering steel. This is consistent with the difference in time-dependent corrosion rate among three materials in the atmospheric exposure test.

This study investigates the interaction between Escherichia coli（E. coli） and various surface states of Cu. Pure Cu was first immersed in ultrapure water for 24 h at 298 K and then oxidized at 673 and 1273 K. Subsequently, its surface chemical states were characterized using X-ray photoelectron spectroscopy （XPS）. The oxidized specimens were immersed in both bacteria-free and bacteria-containing solutions, and the release of Cu ions from each specimen was evaluated. The specimens that existed mainly as Cu^＋ on the surface were found to promote the elution of Cu ions because of the presence of E. coli in the immersion solution. In contrast, the specimen that existed mainly as Cu^2＋ showed no changes in Cu release in the presence of bacteria. XPS analyses conducted before and after immersion in bacteria-free and bacteria-containing solutions showed that the presence of E. coli inhibited the generation of Cu^2＋ on the surface and promoted Cu ion elution. This study proposes that the specific corrosion behavior of Cu in response to bacteria is beneficial for developing its antibacterial properties.

In the paint-coated steel structures under the air-borne sea salt deposition, corrosion damages were progressed severely where rainwater prone to be stagnated, or exposed to a wet-dry cyclic environment due to the dew condensation. The corrosion of the adjacent coating defects would progress with mutual interference because of the electrical short-circuiting under water film. In this research, a model specimen was fabricated to simulate two adjacent coating defects, and the split electrodes group constituted the relatively larger defect. The exposed steel substrate of the split electrodes corresponding to coating defects and the corrosion currents between each electrode were monitored. Besides, the macrocell current between the split electrodes group and its adjacent coating defect was also measured. Test results clarified the corrosion characteristics between the steel substrate of adjacent coating defects in immersion and wet-dry cyclic environments.