Bending strength of porcelains

Abstract Porcelains in the quartz–metahalloysite+kaolin–K-feldspar system with different quartz grain sizes were investigated to study the effect of firing temperature on the bending strength. The degree of vitrification of the fired bodies was determined measuring the bulk density, relative percentages of constituent minerals by XRD and their microstructures using SEM techniques. The maximum bending strength was obtained in the 10–20 μm particle size quartz containing porcelains at 1300 and 1350 °C interval. The distribution of closed pores, their geometric shapes and possible link with each other control the bending strength of the porcelain body. In addition, the presence of unmelted fine quartz grains in the porcelain body also increases the bending strength. It was found that the bending strength increases with both increasing bulk density of the porcelain bodies and the firing temperature, but upon further heating, after reaching the maximum level, the bending strength decreases due to bloating of isolated pores and the disappearance of quartz, which are also associated with a decrease in bulk density.