Preparation of low-cost porous mullite ceramics by recycling fly ash

Abstract

Low-cost porous mullite ceramic was prepared by using bauxite and fly ash as raw material. The porous mullite ceramic was fabricated maintaining 80% bauxite and 20% fly ash composition. Compacted samples were heat treated at four different temperature 1300°C, 1400°C, 1450°C and 1500°C to study the formation of mullite phase. XRD analysis confirmedthe formation of mullite as a major phase at 1400°C and above. It was found that with an increase in the firing temperature up to 1450°C porosity increases, linear shrinkage decreases and density decreases. After 1450°C normal trend was noticed. FESEM microstructure showed the presence ofdistributed pores, lathe-shaped mullite grains, and the glassy phase. The flexural strength was also investigated to find out the mechanical stability of the porous mullite ceramics.Low-cost porous mullite ceramic was prepared by using bauxite and fly ash as raw material. The porous mullite ceramic was fabricated maintaining 80% bauxite and 20% fly ash composition. Compacted samples were heat treated at four different temperature 1300°C, 1400°C, 1450°C and 1500°C to study the formation of mullite phase. XRD analysis confirmedthe formation of mullite as a major phase at 1400°C and above. It was found that with an increase in the firing temperature up to 1450°C porosity increases, linear shrinkage decreases and density decreases. After 1450°C normal trend was noticed. FESEM microstructure showed the presence ofdistributed pores, lathe-shaped mullite grains, and the glassy phase. The flexural strength was also investigated to find out the mechanical stability of the porous mullite ceramics.