Effect of Sintering Temperature on Mullite Ceramics Fabricated from Treated Palm Oil Fuel Ash

Treated palm oil fuel ash waste was used as substitution materials for silica in in order to fabricate mullite ceramic. Alumina powder was added into the treated palm oil fuel ash in order to supply a deficient alumina component according to the alumina/silica molar ratio of mullite. Mullite phase was successfully achieved upon sintering at temperature above 1220 oC besides other minor impurities, such as perovskite, Al2O3 and SiO2. The surface of samples becomes smoother as the sintering temperature increased to 1270 oC whilst forming closed pore morphology. Besides that, the hardness of the samples increased as an increasing in the sintering which is attributed not only to the full densification of pores on the surface, but also due to the presence of mullite phase.