Method of forming a ceramic product
First Claim
1. A method of forming a ceramic product by converting silica to silicon nitride in a carbothermal reduction process in the presence of nitrogen, fabricating the silicon nitride into the desired shape of the ceramic product and sintering the fabricated silicon nitride, characterised in that the carbothermal reduction process is partially completed so as to produce a mixture comprising residual silica and silicon nitride which is fabricated into the desired shape and is heated in a densification step in a nitrogen atmosphere at a temperature of from 1400°
- C. to 2000°
C. to produce a ceramic product comprised of silicon nitride and silicon oxynitride.
1 Assignment
0 Petitions
Accused Products
Abstract
A method of forming a dense ceramic product comprised of silicon nitride and silicon oxynitride or aluminum substituted derivative of either in which silica is subjected to a controlled partial carbothermal reduction process in the presence of nitrogen to produce residual silica and silicon nitride, fabricating the resulting material into the desired shape and heating in a nitrogen atmopshere at a temperature of from 1400° C. to 2000° C. with or without pressure to form the product. The silica may conveniently be derived from pyrolysed rice hulls. The product may also comprise silicon carbide, which may be derived from the carbothermal reduction, and a glassy phase.
-
Citations
10 Claims
-
1. A method of forming a ceramic product by converting silica to silicon nitride in a carbothermal reduction process in the presence of nitrogen, fabricating the silicon nitride into the desired shape of the ceramic product and sintering the fabricated silicon nitride, characterised in that the carbothermal reduction process is partially completed so as to produce a mixture comprising residual silica and silicon nitride which is fabricated into the desired shape and is heated in a densification step in a nitrogen atmosphere at a temperature of from 1400°
- C. to 2000°
C. to produce a ceramic product comprised of silicon nitride and silicon oxynitride. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- C. to 2000°
Specification