# A microwave method for the preparation and sintering of $\beta$ ′-SiAlON

Panneerselvam, M and Rao, KJ (2003) A microwave method for the preparation and sintering of $\beta$ ′-SiAlON. In: Materials Research Bulletin, 38 (4). pp. 663-674.

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A microwave-assisted carbothermal reduction and nitridation (CTR/N) method has been used for successful preparation of monophasic $\beta$ ′-SiAlON starting from kaolinite and carbon black. Phase pure $\beta$ ′-SiAlON has been obtained in under 60 min in microwave field. The z value of microwave prepared $\beta$ ′-SiAlON is found to be 2.95, which is very close to the expected value from kaolinite composition. Formation of $\beta$ ′-SiAlON has been monitored with XRD and MASNMR of 29Si and 27Al; the possible reaction mechanism has been discussed. Kaolinite to $\beta$ ′-SiAlON conversion appears to be a very rapid single-step reaction under microwave irradiation. $\beta$ ′-SiAlON powders have been microwave sintered to 98.7% of theoretical density in 30 min.