ESTIMATION OF METAL OXIDE SOLUBILITY AND UNDERSTANDING CORROSION IN SUPERCRITICAL WATER

摘要

This paper estimates metal oxide solubility in high temperature water for understanding the corrosion environment of supercritical water. The recently proposed method of predicting metal oxide solubility in high temperature water without any fitting parameter is explained in this paper. Chromium oxide, iron oxide, nickel oxide in high temperature water were estimated by the model. Chromium oxide solubility in high temperature region is the lowest among the three oxides (chromium, iron, and nickel), which is supposed to relate to the resistance against the corrosion of chromium including metals. Metal oxide solubility increased with increasing temperature at a higher pH region and at neutral conditions. The result suggests that excess addition of neutralizer in supercritical oxidation enhances corrosion.