Synthesis and characterization of cordierite ceramic from Moroccan stevensite and andalusite

Cordierite (2MgO−2Al ₂O ₃− 5SiO ₂ ) is currently an attractive ceramic material for various applications. This study describes the production of cordierite ceramic by mixing Moroccan abundant raw materials: andalusite (source of Al ₂O ₃ and SiO ₂ ) and “Ghassoul” clay (source of MgO and SiO ₂ ). The clay consists mainly of stevensite. The mixtures (size < 40 μm) were sintered at 1150, 1250 and 1350 °C for 2 h. The phases formed and structural changes by sintering were investigated by X-ray diffraction (XRD), differential thermal analysis (DTA), thermal dilatometry and scanning electron microscopy (SEM). Cordierite and andalusite were the major phases in samples sintered at 1150 °C and 1250 °C. Small amounts of enstatite, mullite and cristobalite were also observed. At 1350 °C, only cordierite was observed. The exothermic peak of the DTA curve at about 1350 °C corresponded to the solid-state formation of cordierite.