Process for preparing a densified beta-phase silicon nitride mat

Details Process for preparing a densified beta-phase silicon nitride mat Process for preparing a densified beta-phase silicon nitride mat

1990-07-24

1993-05-25

Derrington, James

Plastic and nonmetallic article shaping or treating: processes

Including step of generating heat by friction

264 65, 501 97, 501 98, C04B 3558

Patent

active

052137295

ABSTRACT:
A process for preparing an alpha-phase silicon nitride material and thereafter sintering to a densified beta-phase silicon nitride material is disclosed which includes comminuting a slurry including a mixture of silicon powder, water, and at least one densification aid to aid in later densifying of the silicon nitride material, the comminuting being performed to form fresh, non-oxidized surfaces on the silicon powder and to allow substantial chemical reaction between the silicon and the 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 sufficient amount of a nitriding gas including at least nitrogen at a sufficient temperature for a sufficient length of time to form a mass of substantially alpha-phase silicon nitride, and sintering the resultant silicon nitride mass at a sintering temperature of from about 1450.degree. C. to about 2100.degree. C. for a sufficient length of time to convert the silicon nitride from a predominantly alpha-phase material to a predominantly densified beta phase silicon nitride material exhibiting a decrease in bulk volume of the silicon nitride due to the densification.

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