Production of Si{sub}3N{sub}4 Whiskers in Solid Mixtures through Vapor-solid Mechanism Using 2MgO 2Al{sub}2O{sub}3 5SiO{sub}2 as Sintering Additives

摘要

The production of silicon nitride whiskers in solid mixtures under nitrogen-containing atmospheres was investigated. Green bodies made of micron and nano silicon nitride powders with 2MgO·2Al{sub}2O{sub}3·5SiO{sub}2 as sintering additive were sintered at 1500-1560°C in flowing nitrogen-containing atmospheres. Resultantly whisker-like products were formed on the cold side of the graphite boat. X-ray diffraction analysis indicated that the formed whisker were α-Si{sub}3N{sub}4 The products were analyzed by transmission electron microscope. The morphologies of the resulting whisker were varied with sintering temperatures and atmospheres. Dislocation structures were observed on the edge of some whiskers. This suggested that the whisker growth proceeded through a vapor-solid (VS) mechanism. The mechanism of whiskers growth at different temperatures and atmospheres was discussed with a thermodynamic calculation based on a database software.