2018 Volume 67 Issue 11 Pages 466-473
The corrosion would often progress with the mutual interaction between adjacent defects, especially at some locations of paint-coated steel structures where the rainwater or dew stagnated in long-term, because of the occurrence of electrical short circuit around the multiple coating defects.
The objective of this study is to investigate the electrochemical mechanism of mutual interaction between the adjacent coating defects in a stagnant water environment. The model specimens embedded with a plurality of electrodes were fabricated to simulate coating defects, and the corrosion currents were measured between these electrodes. In case of the two electrodes with different diameters, the measurement results show that the anode reaction would be fixed in the electrode with a relative larger diameter, while the cathode reaction would be fixed in the electrode with a small diameter. In addition, when the diameter of the electrode is less than 20 mm, it has been clarified that the linear correlation exists between the area ratio of adjacent electrodes and the macrocell current density, and the relationship was formulated.
