STABILITY OF RARE EARTH OXIDES IN A MOIST ENVIRONMENT AT ELEVATED TEMPERATURES - EXPERIMENTAL AND THERMODYNAMIC STUDIES. PT.2. COMPARISON OF THE RARE EARTH OXIDES

Volatilisation tests enabled the stability of different rare earth sesquioxides, RE2O3 (where RE = Sc, Dy, Er, Yb) to be quantified and the corrosion process to be assessed. Tests were carried out at temperatures ranging from 1000 to 1400 C in moist air with 50 kPa of water at atmospheric pressure, under a flowing gas velocity of 5 cm/s. Together with the volatilisation rate, the nature of the volatile gaseous species was determined. The proposed method allowed the Gibbs free energy of formation of these gaseous volatile species to be assessed. Finally, the stability of each rare earth oxide under a moist environment at high temperature was compared.