The present paper investigates high-temperature sulphate corrosion of basic
refractory ceramics containing magnesium spinels (MgAl2O4, MgFe2O4, MgCr2O4
and their solid solutions) widely used in metallurgy, chemical, ceramic and
glass industry. This group of refractories are exposed to a number of
destructive factors during a working campaign. One of such factors is gas
corrosion caused by sulphur oxides. However, gas sulphate corrosion of basic
refractory materials containing magnesium spinels, which has a great
practical meaning for the corrosion resistance of the material main
components, is not sufficiently examined. This work presents a thermodynamic
analysis of (MgCr2O4, MgAl2O4, MgFe2O4)?SO2?O2?SO3 system aimed to calculate:
i) the standard free enthalpy of chemical reactions, ii) the equilibrium
composition of the gas mixture initially containing SO2 and O2 and iii)
sulphates equilibrium dissociation pressure and equilibrium partial pressure
for the reaction of SO3 with the spinels to predict the temperature range of
corrosion products? stability. A thermochemical calculation provides
information about equilibrium state in the analysed system. In real
conditions the state of equilibrium does not have to be achieved. For this
reason, the results of calculations were compared with experimental data. The
experiment results were consistent with the theoretical predictions.