Method of converting a silicon nitride from alpha-phase to beta- phase, apparatus used therefor, and silicon nitride material made therefrom

摘要

A method of converting non-densified alpha-phase silicon nitride to beta-phase silicon nitride which includes heating a walled container enclosing a non-densified alpha-phase silicon nitride mass to an elevated temperature for a sufficient length of time so that the non- densified alpha-phase silicon nitride mass converts to a beta-phase silicon nitride mass. The walled container is formed of a silicon nitride- containing material which is stable at temperatures of at least 1700 C. and is compatible with silicon nitride. Additionally, the walled container has an opening therein to allow placement of the non-densified alpha- phase silicon nitride mass therein.