Corrosion of nickel aluminate by Ca, Fe, Mg and V oxides and synthetic slags

The corrosion resistance of a stoichiometric NiAl2O4 spinel was studied. NiAl2O4 spinel samples were exposed to either CaO, Fe2O3, MgO, V2O5 or synthetic slags at 1450 °C for 6 h. Two different synthetic slags were used, one containing high amount of Fe2O3, SiO2 and MgO and other with high amount of CaO and Al2O3. In most the cases, NiAl2O4 spinel was not chemically stable and, depending on the nature of the corrosive agent, several corrosion products were formed. The higher reactivity was observed for the system where a synthetic slag with high content of Ca and Al was used. Using the corrosion results and thermodynamic equilibrium calculations (FactSage 6.2) it was possible to elucidate the corrosion mechanisms.