Effect of TiO2, Fe2O3, and Alkali on Mineralogical and Physical Properties of Mullite‐Type and Mullite‐Forming Al2O3‐SiO2 Mixtures: I

Abstract

This report gives the results of the first phase of an investigation to determine the effects of TiO2, Fe2O3, and alkalis on mullite‐forming Al2O3‐SiO2 mixtures. Preliminary tests indicated that the effects of TiO2 might depend on the Al2O3‐SiO2 ratio. Therefore an Al2O3‐SiO2‐TiO2 sub‐system was studied which indicated that 5% TiO2 might be beneficial. Test bars with a composition of 5 TiO2, 65 Al2O3, 30% SiO2 not only had the highest mullitization but also had satisfactory physical properties. A second series of tests was made in which Fe2O3 and/or alkali was substituted for all or part of the 5% TiO2. Fe2O3 and TiO2 reacted similarly in quantities up to 2 or 3%; however, more than 2% alkali was generally harmful. More TiO2 could be tolerated than Fe2O3, especially in the presence of more than 1% alkali. These conclusions are based only on data for sintered materials and may not apply to fused materials.