Al拡散浸透処理材の高温耐食性の交流インピーダンス法による評価

抄録

AC impedance technique has been applied to the evaluation of corrosion resistance of high temperature protective Aluminized coatings in Na₂SO₄-Li₂SO₄ melt at 973 K. The monitoring of corrosion behavior was conducted by the continuous measurement of impedance at 10⁻² Hz. These data reveal that the substrate materials have a great effect on the corrosion resistance of Al coatings. Also, it is found that the corrosion resistance of Al coatings can be improved by preoxidation. The results from AC impedance measurements were well correlated with the results of SEM surface observation. On the basis of the obtained impedance characteristics, a simple model of equivalent circuit has been set up to explain the corrrosion process of Al coating. The AC impedance method is shown to be a useful tool for the evaluation of molten salt corrosion.