Process for preparing an alpha-phase silicon nitride material and thereafter converting to non-densified beta-phase material

Reference Number: N 04-12

Inventors: Edler, James P.; Lisowsky, Bohdan

USPTO Link: 5156830

Invention Summary

A process for preparing an alpha-phase silicon nitride material and thereafter converting to non-densified beta-phase silicon nitride material includes comminuting a slurry including a mixture of silicon powder and water to form non-oxidized surfaces on the silicon powder and to allow chemical reaction between the silicon and water, reducing the water content of the reacted slurry to a degree sufficient to form a resultant dry mass, nitriding the dry mass by exposure to a nitriding gas including at least nitrogen to form a mass of alpha-phase silicon nitride, and converting the resultant silicon nitride mass at a conversion temperature of from about 1450.degree. C. to about 2100.degree. C. to convert the silicon nitride from an alpha-phase material to a non-densified beta phase silicon nitride material.