Influence of MgO on Properties and Microstructure of Mullite Ceramics Synthesized from Coal Fly Ash

摘要

The effects of MgO and temperature on the properties and microstructure of mullite ceramics synthesized from high-aluminium coal fly ash and bauxite are investigated in this paper. The results show that when the batch containing 4 wt% MgO is heated from 1100°C to 1500°C, the bulk density and flexural strength increase obviously with the sintering temperature rising, mullite ceramics with flexural strength as high as 169 MPa can be obtained at 1500°C with the addition of 2 wt% MgO. According to the XRD results, the corundum, cordierite and cristobalite phases disappear completely upon 1400°C, it indicates that MgO addition may effectively promote sintering process. The results of SEM indicate that the prepared ceramics mainly exist in the shape of long parallelepipeds with the aspect ratio of about 7-10.