2018 Volume 31 Pages 6-13
It is difficult to determine precise electrochemical data and analyze corrosion behavior in dilute solution, because dilute solution is a high solution resistance environment. In order to solve these problems, it is necessary to establish an electrochemical measurement method to analyze corrosion behavior. In this study, we examined about electrochemical impedance spectroscopy and coupling current measurement which is a suitable electrochemical measurement method in a low-concentration electrolyte environment using pure zinc, pure iron and stainless steel type 304 (SUS304). In low concentration solution, it was found out that electrochemical impedance spectroscopy has to use two-electrode cell and coupling current measurement is effective method to analyze corrosion behavior. The charge transfer resistance of pure zinc is fixed in 0.0001—0.01 M NaCl solution and decreases in 0.01 M or more. That of Fe drastically decreases in 0.0001—0.001 M, mildly decreases in 0.001—0.5 M and increases in 0.5 M or more. That of SUS304 is fixed in all concentration. The coupling current decreases with decreasing of solution concentration. The reason of decreasing of coupling current is estimated that solution resistance increases by decreasing of solution concentration.
