Mechanical-activated, combustion synthesis of β-SiAlON

This paper describes the synthesis of β-Si6−zAlzOzN8−z (z = 1) powder via combustion synthesis (CS) assisted with mechanical activation by a high-energy planetary ball milling under various nitrogen pressures (0.7, 1.0, 1.5, and 2.5 MPa). Here, we did not examine only the effect of ball milling time and nitrogen pressure on the reaction rate and microstructure of CSed products using XRD and SEM, but also the effect on the nitrogen pressure required for CS of β-SiAlON. The results show that prolonged milling time was quite effective for enhancing the reactivity of raw materials and also for promoting the conversion rate of β-SiAlON. The mechanical activation minimized the required nitrogen pressure for combustion synthesizing β-SiAlON, which the reaction can self-propagate at only 0.7 MPa in nitrogen pressure. Significantly, SEM observation revealed that the rod-like crystals agglomerated together with increasing ball milling time, and became longer and thicker with increasing nitrogen pressure.