定電位分極下における塗装鋼板の劣化挙動とインピーダンス特性
1991 年 42 巻 1 号 p. 89-94
詳細
1991 年 42 巻 1 号 p. 89-94
The electrochemical impedance of coated metals was measured in 5% NaCl solution continuously over 100 hours of exposure. In order to investigate what role the substrate plays in coating corrosion, seven kinds of substrates, including Zn plated steel and alloy steels having Cu, Ti additives were used as test specimens, and were exposed artificially to anodic or cathodic polarization at controlled potential
The investigated system is time dependent, so one should be able to monitor it in situ. The impedance characteristics of the system were derived from the continuous measurement of impedance during exposure and discussed as a function of exposure time Comparison of the results form impedance, and visual observations of coating blisters and cross-cut tests confirmed that AC impedance data can be used effectively to evaluate the effect of the substrate.
It was found that anodic and cathodic polarization exhibit different impedance characteristics in all specimens. Alloy steels with Cu, Ti were found to provide greater protection than Zn-plated steels for both interface performance and substrate corrosion-resistance properties under anodic and free corrosion conditions However, alloy steels with Cu, Ti affords less protection than Zn plated steels under cathodic polarization.
