Sintering, physicomechanical, thermal expansion and microstructure properties of cordierite ceramics based on utilizing silica fume waste

Highlights: • Pure cordierite can be prepared using calcined alumina, fine amorphous silica fume and talc powder mixtures. • The formation of cordierite started at 1300 °C, it was enhanced by increasing the sintering temperature up to 1400 °C. • The optimum physical properties were obtained at 1350 °C with 10.323% apparent porosity and 2.112 g/cm³ bulk density. • Thermal expansion of cordierite sintered at 1350 °C decreased, producing CTE from −8.18 × 10⁻⁷ at 200 °C to -3x10⁻⁷ at 900 °C. • At 1350 °C, cordierite showed good dielectrical constant of 5.5, fracture toughness of 2.71 MPa m^0.5 & 5.38 GPa micro hardness. In the present work, cordierite ceramics are prepared through the solid reaction method using calcined alumina, silica fume, and talc as starting materials. Pressed samples and powders are sintered and calcined at various temperatures; 1300, 1350 and 1400 °C. The particle size, phase composition and morphology of the raw materials, and the calcined and sintered cordierite samples are analyzed. The physical properties, surface area, DSC, TG, thermal expansion and electrical and mechanical properties of the cordierite samples are also studied. In addition, the physical, thermal, mechanical, and electrical properties are investigated under the effect of heat treatment. The results indicated that 1350 °C is the optimum sintering temperature with 10.323% apparent porosity and 2.112 g/cm³ bulk density and the crystallization of the cordierite ceramic was crack-free and has low thermal expansion. It also, showed good dielectrical constant of 5.5 and good mechanical properties such as 2.71 MPa m0.5 fracture toughness and 5.38 GPa micro hardness.