Ceramics-Silikáty 49, (2) 97 - 103 (2005)

Magnesium aluminate gel precursor has been synthesized by rapid co precipitation technique at a relatively low temperature. This gel exhibits the evolution of spinel phase at significantly lower temperature than solid state sintering; however it is associated with secondary phase like corundum and periclase at higher temperature. The gel has been incorporated in different concentration 0.5-4.0 wt.% to a high alumina based castable to fabricate in situ spinel-alumina monolithic refractory. Uncontrolled agglomeration and an enormous amount of -OH,-NH₂ and C=O groups associated with the precursor gel indicates a serious apprehension about the performance of the castable. Nevertheless an optimum amount of 2.0 wt.% of spinel gel renders a satisfactory role towards the physical properties of the castable. The microsilica content of the original batch should be reduced to eliminate the detrimental CaO-Al₂O₃-SiO₂ phase generated in the matrix.