Fundamental Study on Corrosion Characteristics between Steel Substrate of Adjacent Paint Coating Defects in Immersion and Wet-dry Cyclic Environments

Abstract

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.