Effect of variation of Al2O3 : SiO2 molar ratio on microstructure and thermomechanical properties of electrical porcelain insulator

The effect of variation of Al2O3 : SiO2 molar ratio through substitution of quartz by calcined bauxite from 0-10% (w/w) on microstructural and thermo-mechanical characteristics of standard porcelain composition has been investigated during firing from 1150-1225 degrees C/2 h. The fired porcelain bodies were characterized by variation in linear shrinkage, bulk density, apparent porosity, flexural strength, X-ray diffraction analysis and SEM study. The remarkable improvement in thermo-mechanical and electrical properties with well inter-locked microstructure were evidenced in electrical porcelain composition based on 7.5% substitution of quartz by calcined bauxite during firing at 1200 degrees C/2 h.