Process for producing ceramic raw materials
AssigneeKemira Oy
InventorsVesa-Pekka Judin, Hayha, Pertti Koukkari
Life of this patent
Estimating the term…
Abstract
The invention relates to a process for the production of silicon ceramic whiskers and silicon ceramic powder from silicon fluoride and ammonia or a hydrocarbon, at an elevated temperature. According to the invention, the hydrocarbon or ammonia (4) is decomposed separately at a high temperature into reactive carbon or nitrogen and hydrogen, whereafter the carbon or nitrogen radical thus obtained is further in a gas phase contacted with reactive silicon formed therein from silicon difluoride, in order to deposit finely-divided silicon nitride or silicon carbide out from the gas phase.
Claims18
A process for the production of finely-divided silicon nitride which comprises:
- (a) heating ammonia at a temperature sufficient to decompose said ammonia into monatomic reactive nitrogen;
- (b) reacting solid silicon and silicon tetrafluoride, separately from said ammonia decomposition in step (a), at a temperature sufficient to form silicon difluoride;
- (c) producing reactive silicon in the gas phase from said silicon difluoride of step (b);
- and
- (d) contacting said reactive nitrogen in a gas phase with said reactive silicon, in order to deposit a finely-divided silicon nitride out from the gas phase.
A process for the production of finely-divided silicon nitride which comprises:
- (a) reacting gaseous silicon tetrafluoride and solid silicon at an elevated temperature of about 1100.degree. C. to about 1400.degree. C. in order to form reactive silicon difluoride;
- (b) decomposing ammonia separately from step (a), in order to produce reactive nitrogen;
- (c) reducing the temperature of said reactive silicon difluoride in step (a) in order to form reactive silicon;
- and
- (d) contacting said reactive nitrogen with said reactive silicon to form silicon nitride.
A process for the production of finely-divided silicon carbide which comprises:
- (a) heating a hydrocarbon at a temperature sufficient to decompose the hydrocarbon into monatomic reactive carbon and hydrogen;
- (b) reacting solid silicon and silicon tetrafluoride, separately from said hydrocarbon decomposition in step (a), at a temperature sufficient to form silicon difluoride;
- (c) producing reactive silicon in the gas phase from said silicon difluoride of step (b);
- and
- (d) contacting said reactive carbon in a gas phase with said reactive silicon in order to deposit finely-divided silicon carbide out from the gas phase.
A process for the production of finely-divided silicon carbide which comprises:
- (a) reacting gaseous silicon tetrafluoride and solid silicon at an elevated temperature of about 1100.degree. C. to about 1400.degree. C. in order to form reactive silicon difluoride;
- (b) decomposing a hydrocarbon separately from step (a), in order to produce reactive carbon and hydrogen;
- (c) reducing the temperature of said reactive silicon difluoride in step (a) in order to form reactive silicon;
- and
- (d) contacting said reactive carbon with said reactive silicon to form silicon carbide.
Dependencies are inferred from the claim text.