Effect of Addition of Al2O3-SiO2 Gel Powder on Strength of Al2O3-MgO Unfired Bricks

Al2O3-MgO unfired brick were prepared by using brown corundum, white corundum, fused magnesia and alpha-Al2O3 as main starting materials, Al2O3-SiO2 gel powder as a binder. The effects of Al2O3-SiO2 gel powder on the strength of Al2O3-MgO unfired bricks were investigated. The phase composition was characterized by X-ray diffraction (XRD). The results showed that with an increase of Al2O3-SiO2 gel powder content, room temperature strength first increased and then decreased, and reached an optimum value at 5.5% addition. The hot modulus of rupture continuously increased. This mainly was related to the reactivity of Al2O3-SiO2 gel powder and the formation of mullite at high temperature.