Preparation of Mullite Porous Ceramics by the Composite Method of Foaming and Pore-Forming Agent Method

To prepare mullite porous ceramics with low thermal conductivity and high strength, taking kyanite tailings and α-Al2O3 as the main raw materials, the mixture after adding sawdust and foaming agents was cast into shape and heated at different temperatures. The bulk density, porosity and mechanical properties of the sample were tested at room temperature. The phase composition and microstructure were analyzed using X-ray diffraction and scanning electron microscopy. The results show that as the sawdust addition increased, the apparent porosity of the sample increased; the compressive strength and the thermal conductivity decreased. Increasing the firing temperature can promote the densification, improve the compressive strength and increase the thermal conductivity of the sample. When the firing temperature was increased to 1500°C, the ceramic reaction was basically completed. When the sawdust content was low, the sawdust was almost surrounded by the material, and the pore distribution was relatively dispersed. As the sawdust content increased, the pore distribution became more con-centrated, and there were more connected pores. When the sawdust addition was 10% (w) and the heat treatment temperature was 1500°C, the mullite porous ceramics would have high compressive strength and low thermal conductivity.