The non-isothermal kinetics of mullite formation in mechanically activated kaolinite-alumina ceramic system

Abstract

The non-isothermal kinetics of mullite formation from both non-activated and mechanically activated kaolinite + alumina ceramic system have been studied by differential thermal analysis (DTA). The mixture of kaolinite and alumina was activated mechanically in a planetary mill, while amorphization in the kaolinite and alumina structure was studied by X-ray diffraction analysis. The activation energies depending on the conversion for mullite formation have been calculated from the DTA curves by using the non-isothermal method of Coats and Redfern at heating rates of 5, 10, 15, and 20 A degrees C min(-1). The mechanical activation of the kaolinite and alumina mixture resulted in the decrease in activation energy values for mullite formation.