Formation of Cordierite in MgO-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> Glass Powder Compacts Containing Crystalline Filler

The influence of crystalline filler such as alumina and cordierite crystals on the formation of cordierite in MgO-Al2O3-SiO2 glass was investigated. The glass in which no cordierite phase is formed is smaller in Al2O3 content than stoichiometric cordierite. Alumina fillers were dissolved in the glass during firing, resulting in increase in alumina content in the glass. Cordierite was formed in the glass powder compact containing alumina fillers formed by firing at 950°C. On the other hand, cordierite fillers were found to play a role as the site for heterogeneous nucleation, and also to lower the precipitation temperature of the cordierite phase in the glass. Cordierite was formed in the glass containing cordierite fillers by firing at 850°C. By firing the powder compacts containing both alumina and cordierite, larger amounts of cordierite can be formed because of the combined effects of each filler.