金属間化合物FeAlおよびFeAl(Cr)の塩酸水溶液中におけるアノード分極特性

概要

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Corrosion behaviors of intermetallic compounds FeAl and FeAl(Cr) were investigated. Steady-state polarization curves of FeAl and FeAl(Cr) were measured in solutions of various pH (pH 0-3) containing chloride ions. Protective regions were observed for FeAl(Cr), even in the HCl solutions of pH 0 and 1. Furthermore, FeAl(Cr) showed a self-passive state in solutions of pH 2-7. In contrast, FeAl showed no protective behavior in a pH 0 solution. Its self-passive regions were smaller than those of FeAl(Cr). The passive film formed on FeAl(Cr) immersed in 1 M HCl solution for 432 ks caused a shift in the corrosion potential by about 130 mV to the noble direction. The potential width of the protective region increased from 160 mV to 300 mV. Moreover, a considerable decrease was observed in passive current density: more than one order. The passive current density of FeAl(Cr) after long-term immersion in HCl solution was less than that of SUS316 steel. Results suggest that aluminized steel with a coating layer of FeAl(Cr) and appropriate immersion treatment in HCl solution can show high corrosion resistance comparable to that of conventional stainless steels.
2010-07-01