High Temperature Corrosion of Chromium and Chromium (III) Oxide in Chlorine and Chlorine‐Oxygen Mixtures

Abstract

The chlorination kinetics of Cr between 650° and 800°C is characterized by a time‐constant weight loss of the specimen caused by volatilization of and . At low pressures also a scale is formed consisting of and. The rate‐determining step is the diffusion of volatile products across the laminar boundary layer. pellets show time‐constant weight loss in and mixtures. In the mixtures, the rate constant of the corrosion of is about a hundred times smaller compared to the chlorination of Cr in the absence of . It increases with the fourth root of the pressure and linearly with the pressure indicating that seems to be the only reaction product. In a mixture of and , the corrosion of Cr is inhibited due to formation of an outer layer and of as the only volatile product. Since can be volatilized as described above, preoxidized samples of Cr exhibit no long‐time corrosion resistance in .