Preparation of Fly Ash-Based Porous Ceramic with Alumina as the Pore-Forming Agent

Low-cost porous ceramic from fly ash with alumina as the pore-forming agent was produced. The effect of the alumina content on line shrink, bulk density, mechanical strength, porosity, and phase composition of porous ceramic were investigated in detail. The results showed that the addition of alumina can help to improve the porosity and then it can change the pore structure of porous ceramic. Meanwhile, the addition of alumina can react with SiO2 in fly ash which can form the mullite. With the increase of alumina content, the content of quartz decreased gradually, while the alumina and mullite increased. Furthermore, the pore size becomes uniform and the permeability increased gradually. After sintering at 1250 ℃ for 0.5 h, the porous ceramic has been obtained the bending strength of ≥ 35MPa and the porosity of ≥ 28% with the addition content of alumina (25 wt%).