Effect of chamotte on the structural and microstructural characteristics of mullite elaborated via reaction sintering of Algerian kaolin

摘要

Mullite [3Al2O32SiO2] was synthesized by reaction sintering of Algerian kaolin of Djebbel Debbagh-Guelma located in the North-East of Algeria and chamotte. The mixture powders of kaolin and chamotte were milled, dried and cold compacted using a uniaxial press. The green samples were sintered for 2?h at 1350?°C. Powders’ morphology, structure and microstructure of the sintered samples were studied by means of X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electronic microscopy (SEM), thermogravimetric and thermodifferential analysis (DTA/TGA) and the helium pycnometer (AccuPyc II 1340).The results showed that DD3 kaolin has a silica content of 41% and alumina of 35%. X-ray analysis revealed that the major phases of the DD3 kaolin was kaolinite along with a muscovite and todorokite. After sintering, the ceramics composite composed mainly of mullite and cristobalite. The added chamotte increases the mullite formation, the apparent density from 2.7 to 2.75?g/cm3, decreases the porosity from 4.70 to 4.43% and a densification higher than 95%.