Effect of V2O5 on the properties of mullite ceramics synthesized from high-aluminum fly ash and bauxite

In this communication, high-strength mullite ceramics was prepared from bauxite and high-aluminum fly ash that is a by-product of coal combustion in thermal power plants. The effects of the doping V2O5 on the bulk density, apparent porosity, bending strength and microstructure of mullite ceramics were studied in detail. It was indicated that 5-10 mol% V2O5 reduced the sintering temperature by 50 deg. C. The apparent porosity and water absorption of the mullite ceramics decreased with increasing V2O5 content. Mullite ceramics with bending strength as high as 108 MPa were obtained at 1500 deg. C with the addition of 10 mol% V2O5. X-ray diffraction analysis suggested that the prepared ceramics was mainly in phase of mullite, and scanning electron microscope images confirmed that it mostly existed in the shape of a long parallelepiped. This research may provide a new method in utilizing the vast resources of fly-ash waste from power plants in the production of low-cost mullite-based engineering materials.