Effect of mechanical activation on mullite formation in an alumina-silica ceramics system at lower temperature

Abstract

Purpose This work aims to analyze the effect of mechanical activation on structural disordering (amorphization) in an alumina-silica ceramics system and formation of mullite most notably at a lower temperature using X-ray diffraction (XRD). Also, an objective of this work is to focus on a low-temperature fabrication route for the production of mullite powders. Design/methodology/approach A batch composition of kaolin, alumina and silica was manually pre-milled and then mechanically activated in a ball mill for 30 and 60 min. The activated samples were sintered at 1,150°C for a soaking period of 2 h. Mullite formation was characterized by XRD and scanning electron microscopy (SEM). Findings It was determined that the mechanical activation increased the quantity of the mullite phase. SEM results revealed that short milling times only helped in mixing of the precursor powders and caused partial agglomeration, while longer milling times, however, resulted in greater agglomeration. Originality/value It is noted that, a manual pre-milling of approximately 20 min and a ball milling approach of 60 min milling time can be suggested as the optimum milling time for the temperature decrease succeeded for the production of mullite from the specific stoichiometric batch formed.

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