Fabrication of SiO<sub>2</sub> Porous Ceramics from Rice Husk Ash

Abstract

Porous silica ceramics were prepared from rice husk ash with a small amount of soft clay as workability agent by the in situ combustion pore-forming technique. Then, the effects of the forming pressures on the linear shrinkage, density, porosity, absorption of water and mechanical strength were investigated. The results showed that the pores in the samples consisted of two groups. One was original porous texture from rice husk silica, which ranged from 1-10 μm. The other was formed by burning of carbon and grain packing. Obviously, the greater the forming pressure, the denser the sample. Especially, the amounts of the pores with bigger diameter dropped significantly when the forming pressure was greater than 25KN. Porous ceramics with density 1.07g/cm3have high porosity and excellent comprehensive properties up to 10MPa.The preparation of porous ceramics utilizing high content rice husk would provide advantages of economical and ecological aspect.