China's Refractories

Abstract:

Corundum-mullite porous ceramics (CMPCs) were fabricated using fly ash and aluminum ash as the raw materials, adding different amounts of starch (0, 10%, 20%, and 30%, by mass) as the pore-forming agent, molding and firing at 1 200 °C for 1 h. The apparent porosity, the bulk density, the cold compressive strength, the thermal shock resistance and the thermal conductivity of the CMPCs were tested. The phase composition and the microstructure of the CMPCs were characterized by XRD and SEM. The effect of the starch addition on the properties of the CMPCs was studied. The results show that: (1) the CMPCs with high porosity can be successfully prepared by adding starch as the pore-forming agent and firing at 1 200 °C for 1 h; (2) with the starch addition increasing, the porosity increases; the cold compressive strength and the number of the quenching cycles of the CMPCs decrease, but they remain at high levels; meanwhile, the thermal conductivity decreases; (3) generally, when adding 20 mass% starch, the CMPC has the apparent porosity of 48.6%, the cold compressive strength of 52.1 MPa, the quenching cycles of 5 and the thermal conductivity of 1.63 W·m^-1·K^-1 and 1.52 W·m^-1·K^-1, respectively, at 25 °C and 500 °C, showing good performance.

Key words: fly ash, aluminum ash, corundum-mullite porous ceramics, starch, pore-foaming agent