純鉄の高温酸化に及ぼす微量の塩化水素の影響

抄録

Degradation of pure Fe was examined under oxygen including a small amount of HCl at high temperatures by measurement of mass change of specimens, observation and analysis of scales formed on the specimens. At the temperature of 873 K, mass gain of Fe in an 1%HCl atmosphere increased with time and was larger than that in pure O₂. The mass gain at temperatures higher than 1073 K increased in an early stage, then turned negative after longer oxidation period. At these temperatures, the magnitude of mass loss after descaling measured in the 1%HCl atmosphere was rather smaller than that measured in the pure O₂ atmosphere. When the decrease in mass gain was observed at 1173 K, the corrosion product was formed like a balloon shape. It was revealed by EPMA analysis that the mass loss at 1073 K was due to producing FeCl₂ which has very high vapor pressure at the temperature. From these results, the high temperature oxidation mechanism of Fe in 1%HCl was discussed thermodynamically.