Effects of Al2O3 addition on the phases, flow characteristics and morphology of the porous kaolin ceramics

The effects of 30, 40 and 50 wt.% Al2O3 particle addition on phases, flow characteristics and morphology of the porous kaolin ceramics sintered at 1100–1300 °C for 1.5 h have been investigated. Mullite content increases with increasing the sintering temperature, but it decreases with increasing the Al2O3 addition. Average pore diameter enlarges and open porosity increases owing to the Al2O3 addition. Specific permeability has been shown to improve with the increases of the sintering temperature and Al2O3 addition. Penetrating porosities decrease significantly from 41.2 to 14.6% and 29.1 to 16.9% as the sintering temperature is increased from 1100 to 1300 °C for the samples with additions of 30 and 40 wt.% Al2O3, respectively. A maximum value is obtained at 50 wt.% Al2O3 addition, when sintered at 1200 °C. Tortuosity shows a similar trend as that of penetrating porosity. Effects of Al2O3 additions on the morphology of pores are shown to vary from round to irregular shapes.