Mullite/ β-spodumene composites: Preparation and characterization

Mullite/ β-spodumene composites were fabricated by the addition of 5 up to 20 mass% β -spodumene powder to mullite matrix. Both mullite and β-spodumene were prepared by sol-gel technique. The batches were uniaxially pressed into discs and rectangular bars, then pressureless sintered at 1400 °C up to 1700 °C for 1 h. Mechanical and thermal properties, as well as microstructure and phase composition were carried out on the sintered composites. The results show that although the increase in the soft β-spodumene reduces the hardness and the thermal expansion of the composites, they lower the firing temperature and enhance the flexural strength. The study indicates that β-spodumene content has a noticeable effect on the composites thermal expansion coefficient. It also shows that it is possible to tailor mullite/ β-spodumene composite with adjusted thermal expansion coefficient by changing the mullite to β-spodumene ratio.