Algerian kaolinite used for mullite formation

In the present study, mullite was synthesized through reaction sintering of Algerian kaolinite and high purity alumina. The raw powders were wet ball milled in a planetary ball mill. Powders' morphology and the microstructure of the sintered samples were characterized by means of a scanning electron microscope. An X-ray diffractometer equipped with a heating facility and a differential thermal analyzer were used to follow mullite formation. Cylindrical specimens were produced by uniaxial cold compaction at a pressure of 75 MPa and sintered at different sintering temperatures for different sintering times. The heating rate was 10 °C/min. It was found that Algerian kaolinite was suitable for mullite production through reaction sintering with pure Al2O3. Formation of complete mullite occurred at 1550 °C. A relative density of 94% (of the theoretical density) was achieved at a relatively low sintering temperature of 1600 °C and a sintering time of 4 h.