Effects of different kinds of sillimanite minerals on the properties of mullite ceramic foams

Abstract

In order to improve the mechanical properties of mullite ceramic foams, vacuum infiltration with different kinds of sillimanite minerals slurries(andalusite, sillimanite and kyanite) was used to prepare mullite ceramic foams. The effects of the kinds of sillimanite minerals on the mechanical properties, phase compositions, thermal shock resistance of the as-prepared mullite ceramic foams were systematically investigated. The results showed that the compressive strength and thermal shock resistance of mullite ceramic foams prepared with andalusite slurries were higher than the mullite ceramic foams prepared with kyanite slurry and sillimanite slurry. However, the apparent porosity and linear expansion of mullite ceramic foams with andalusite was lower than the mullite ceramic foams with kyanite because of the difference in decomposition temperature and decomposition rate of andalusite, sillimanite and kyanite. In addition, when the calcination temperature reached 1400 °C, it was beneficial to promoting the growth of mullite grains that andalusite slurries were used as infiltration slurries to produce ceramic foams. Furthermore, after calcination, the low thermal stresses were generated within the struts of mullite ceramic foams with andalusite, which positively influenced the thermal shock resistance and strength of the mullite ceramic foams.