Effects of La2Ce2O7 on the phase composition, microstructure, wetting behaviour and corrosion resistance of magnesia refractory

The addition of rare earth oxides has a significant impact on the improvement of thermal properties of refractory materials. Magnesia refractory with La2Ce2O7 was prepared by high-temperature solid-phase synthetic sintering at 1873 K for 5 h using fused magnesia as raw materials, CeO2 and La2O3 as addition, respectively. The effect of La2Ce2O7 on the phase composition, microstructure, apparent porosity, bulk density, wetting behaviour and corrosion resistance with steel of fused magnesia were investigated. When the content of La2Ce2O7 was 20 wt%, the results showed that as-prepared samples from fused magnesia with an apparent porosity of 17.63% and a bulk density of 3.11 g·cm-3 were obtained by high temperature solid-phase sintering reaction at 1873 K for 5 h, respectively. Due to the addition of La2Ce2O7, and raw materials in the impurity phase CaO and SiO2 for the reaction, the generation of a small amount of CaLa4(SiO4)3O and La8.89Si6O25.9 high melting point phase, plugging the air holes, thus improving the bulk density of the fused magnesia and reduce its apparent porosity. The ability of steel corrosion of as-prepared samples from fused magnesia doped with La2Ce2O7 have better resistance than conventional fused magnesia, which the thickness of the corrosion layer was reduced by 42.1% compared to as-prepared samples without La2Ce2O7.