Properties of commercial MgO-Al2O3 refractories as related to their phase composition and microstructure

The effect of phase composition and microstructure of some MgO-Al2O3 refractories on their densification and refractory properties was investigated. The phase composition of refractory samples processed up to firing at 1700 degrees C was calculated and confirmed by XRD. A computerised SEM attached with an EDS unit was used to investigate the microstructure of the dense samples. Densification and the refractory properties of these samples were determined and the results are discussed as related to their composition and microstructure. It is concluded that dense and highly refractory magnesia-spinel and spinel grains as well as composite spinel-bonded magnesia and alumina grain batches could be processed from the commercial Chinese dead-burned magnesite and calcined bauxite materials up to firing of their corresponding batches at 1700 degrees C. The processed refractories are recommended for application in lining cement, steel and glass furnaces to replace chrome-bearing refractories in order to eliminate dangerous environmental pollution.