On the stability of refractory materials under industrial vacuum conditions: Al2O3, BeO, CaO, Cr2O3, MgO, SiO2, TiO2 systems

Abstract The volatility and stability of refractory oxides, such as Al 2 O 3 , BeO, CaO, Cr 2 O 3 , MgO, SiO 2 and TiO 2 , towards oxygen has been studied using data of standard free energy for the vaporization processes and the kinetic theory of gases. The analysis has been made removing the congruence condition and examining the system's behaviour in the monovariant region. The results appear to be a useful tool in choosing the experimental strategy for getting simultaneous information on both volatility and stability towards oxygen. Some of the experimental data available in the literature on mixtures of oxides have been compared with ours, and the good qualitative agreement obtained will probably allow the application of our approach also to commercial refractories.