High temperature interaction of pure Cr with KCl

In this study, high temperature reactions between pure Cr and KCl at 650°C have been investigated in air and pure oxygen using both exposure tests and thermogravimetric analysis. The degradation of pure Cr strongly depends on the amount of KCl and, basically, a much greater corrosion rate occurs beneath a KCl deposit than in KCl vapour. In both cases, pure Cr is heavily consumed and the reaction products include a rather porous Cr ₂O₃ matrix plus a small amount of potassium chromate. The dominant degradation step is closely related to a liquid phase enhanced corrosion process, in particular, due to the preferential formation of potassium chromate and its further combination with KCl, forming various low melting point eutectic mixtures. Referring to the compositions and morphologies of the corrosion products, as well as considering the kinetic and thermodynamic properties, possible reaction paths for pure Cr have been proposed.