Microstructure and thermo mechanical properties of a talc doped stoneware composition containing illitic clay

The influence of talc on the thermo mechanical properties and microstructure of a stoneware composition containing illitic clay has been studied. It has been observed that there is an optimum addition of talc/feldspar combination to reach proper vitrification at a relatively lower temperature. The addition of 3 mass% talc resulted in increased flexural strength (69.7 MPa at 1200 °C), decreased water absorption value (0.28%) and increased relative density (94.83%). Decrease in residual quartz content with progressive addition of talc led to decrease in percent thermal expansion upto 3 mass% talc addition, beyond which reverse trend was observed due to increased proportion of the high expansion glassy phase. Addition of talc had little effect on the mullite content of the fired body. The decrease of sintering temperature of bodies containing more than 3 mass% talc led to enlargement of pores which is responsible for decrease in the fired MOR of the matured specimens.