Effect of quartz grain size on elastic and thermal expansion properties of porcelain

Abstract

Quartz powders having different particle size distributions were mixed with feldspar and kaolin to make traditional porcelain bodies. The effects of quartz particle size on the elastic modulus and thermal expansion characteristics of these porcelains were investigated. Porcelain bodies prepared from quartz particles finer than 20 µm and heat-treated between 1275 and 1300 °C showed Young’s modulus 80 GPa or higher, and showed coefficient of thermal expansion (CTE) above 6 × 10⁻⁶/K. Porcelain bodies prepared from coarser quartz particles in size showed elastic modulus 35 GPa or lower, and the CTE below 5.3 × 10⁻⁶/K. These differences were caused by sufficient sintering and microcracks due to the difference in thermal expansion between quartz and glass-mullite matrix, and the critical quartz grain size for microcracks in porcelain was found to be in the range of 20–32 µm. Wearability and polishing performance of abrasive media with varying Young’s modulus were also studied.