Effect of yttria on sintering and microstructural behavior of reaction sintered mullite based on bauxite, fly ash and precipitated silica

The present investigation on the effect of Y2O3 towards the sintering behavior of mullite compacts revealed that rapid mullitization occurred through nucleation and normal grain growth due to the formation of yttrious silicate glassy phase. The intergranular voids were progressively eliminated by yttrious silicate glass leading to significant decrease in porosity with the corresponding remarkable rise in mechanical strength of sintered compacts. The uniform dispersion of microfine corundum grains into the mullite matrix with 1.5% Y2O3 content was noticed during sintering at 1550 °C and above.