High-performance chromite by structure stabilization treatment

Chromite is an important raw material applied in refractories. Efforts have been made to obtain high-performance chromite by adding MgO and Al2O3from the viewpoint of structure optimization. In order to explore the effect of Al2O3and MgO on the structure, two formulas, i.e., Mg-rich and Al-rich ones, were selected. The phase and microstructure development of samples heated in the temperature range of 1200–1600 °C were studied by X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry. MgO and Al2O3added have diffused into chromite successfully by heat treatment. MgO diffuses into chromite, occupying the tetrahedral vacancies caused by the diffusion and oxidation of Fe2+ions to stabilize the structure. Al2O3diffuses into the surface layer of chromite, forming spinel-sesquioxide structure. Al-rich sample which has spinel-sesquioxide structure shows better corrosion resistance toward fayalite slag than Mg-rich sample which has single spinel structure by blocking the interdiffusion between Fe2+ions in fayalite slag and Mg2+ions in chromite.