Influence of ZrO 2 and WO 3 doping additives on the thermal properties of porous mullite ceramics

Abstract Porous mullite-corundum refractory ceramics were produced by a patented slurry slip casting method from compositions based on commercially available α-Al 2 O 3 and γ-Al 2 O 3 , fused SiO 2 and kaolin. Pores were formed as a result of a chemical reaction of aluminium with water. The influence of usage of raw materials and doping additives such as micro-size ZrO 2 and WO 3 on the sintering temperature, formation of crystalline phases, linear thermal expansion, thermal conductivity and thermal shock resistance of mullite-corundum ceramic was studied. The best thermal shock resistance and, simultaneously, lower thermal conductivity was achieved for the samples doped with WO 3 . This was due to the influence of micro-sized WO 3 on the change in γ-Al 2 O 3 modification to α-Al 2 O 3 and on the structure of mullite ceramics.