Effect of Alumina Reactivity on the Densification and Properties of Al ₂ O ₃ –Cr ₂ O ₃ Refractories

Alumina‐chrome (Al ₂ O ₃ –Cr ₂ O ₃ ) refractories with Al ₂ O ₃ :Cr ₂ O ₃ molar ratio 1:1 were synthesized in the temperature range of 1400–1700°C by conventional solid–oxide reaction route. The effect of different aluminas (viz., hydrated and calcined) on the densification, microstructure, and properties of Al ₂ O ₃ –Cr ₂ O ₃ refractories was investigated without changing the Cr ₂ O ₃ source. The starting materials were analyzed to determine the chemical composition, mineralogy, density, surface area, and particle size. Sintered materials were characterized in terms of densification, phase assemblage, and mechanical strength at room temperature and at higher temperatures. Microstructural evolution at different sintering temperature was correlated with sintering characteristics. It can be concluded that the Al ₂ O ₃ –Cr ₂ O ₃ refractories prepared with hydrated alumina as Al ₂ O ₃ source show better densification and hot mechanical strength than corresponding calcined variety.