Compositional variation of sialon phase produced after carbothermal reduction and nitridation of a vermiculite-polyacrylonitrile intercalation compound

Abstract

Vermiculite (AlMg hydrated layer silicate) has been used as raw material for the synthesis of nitrogen ceramics in the SiAlMgON system in the presence of carbon. Successive intercalation of butylammonium cation and acrylonitrile, followed by polymerization and cyclization of the polymer and thermal treatment under nitrogen flow, have produced the carbothermal reduction and reactive nitridation of the precursor, yielding β-Si 3N 4 and β-sialon as nitrided phases. Thermal evolution of the intercalated samples from 1000°C to 1500°C has been studied by XRD and IR spectroscopy. The compositional variation of sialon phase was found to be a function of heating temperature and soaking time at 1400°C. These facts were explained on the basis of a complex vapor-liquid-solid mechanism.