Abstract
Coal ash and aluminum sludge are industrial wastes discharged in large amounts by electric power plants and aluminum sash factories. In this study, aluminum sludge was heat treated at a temperature of 1573K for 2 hours to change the α-alumina crystal structure. The silica (SiO2) contained in coal ash and the alumina (Al2O3) contained in aluminum sludge were combined to synthesize mullite by using a spark plasma sintering apparatus. While varying the composition ratio of the fly ash and α-alumina sludge, the mechanical properties were investigated. As a result, the bending strength of the composite material (composition weight ratio of coal ash and α-alumina sludge 2:3) showed an extremely high value of 270MPa at a sintering temperature of 1573K and holding pressure of 40MPa. Using X-ray analysis, the existence of mullite crystal structures in this material was confirmed.
