Vaporisation of chromia in humid air

Thermodynamic data for the computation of the vaporisation of Cr2O3(s) in humid air show significant deviations between each other which lead to large differences in the computed partial pressures. The vaporisation of Cr2O3(s) in air with different humidities, p(H2O)=0.0007 bar to p(H2O)=0.3 bar, was, therefore, investigated at constant temperature of 1223 K by the vapour transpiration method. The results obtained were explained by the formation of CrO3(g) as major vapour species at low p(H2O) and the formation of CrO2(OH)2(g) as major vapour species at high p(H2O). The pressures evaluated are compared with those obtained by thermodynamic computations using different data bases.