Effect of temperature on the reaction sintering of mechanically activated ZrSiO4–Al2O3 mixture

In the present study, the effect of temperature on the dissociation of ZrSiO4 and formation of mullite during the reaction sintering of mechanically activated ZrSiO4–Al2O3 powder mixture was investigated. In this regard, a mixture of ZrSiO4 and Al2O3 with the stoichiometric composition was mechanically activated for different times up to 60 h and then reaction sintered at different temperatures. Structural changes during the mechanical activation and reaction sintering were determined by X-ray diffraction (XRD). The results showed that by 20 h of mechanical activation, the starting temperature for mullite formation during the reaction sintering decreased from 1550 °C to 1200 °C. The dissociation of ZrSiO4 and formation of mullite increased by increasing both the mechanical activation time and the reaction sintering temperature. Complete formation of mullite–zirconia composite was observed after 60 h of mechanical activation and subsequent reaction sintering at 1400 °C for 2 h, which is about 200–250 °C lower than the temperature commonly used in the reaction sintering of ZrSiO4–Al2O3 mixture.