Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1994-03-24
1995-11-28
Niebling, John
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
C01B 2106
Patent
active
054704464
ABSTRACT:
A process for the production of substantially crystalline silicon nitride comprising heating a mixture of ammonia and a silicon halide by means of an electric plasma formed in a stream of a non-oxidizing gas is described. Energy is transferred to the stream of gas at a rate of at least 30 kilowatts per mole of silicon halide per minute and at least 25 kilowatts. In a preferred embodiment gaseous material is caused to recirculate within the reactor so that there is a recirculation ratio (RR) greater than 2.5 where RR is defined by ##EQU1## wherein M.sub.n =mass flow of gas stream through the inlet nozzle, R=internal radius of the reactor into which said gas stream flows, M=mass flow of gases in the reactor at a distance 4R downstream from the inlet nozzle, R.sub.n =radius of inlet nozzle, D.sub.n =density of gas stream passing through the inlet nozzle, D=density of gases in reactor at a distance 4R downstream from the inlet nozzle. The degree of crystallinity of the silicon nitride prepared according to this method is very high and typically greater than 85%
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Harmsworth, P. D., et al., "Gas Phase Production of Silicon Nitride Using a DC Plasma", Paper presented at the 4th International Symposium on Ceramic Materials & Components for Engines, Goteborg, Sweden, Jun. 1991.
Ellison Anthony W.
Harmsworth Patrick D.
Jennett Timothy A.
Martin Dave
Mayekar Kishor
Niebling John
Tioxide Specialties Limited
Tungol Maria Parrish
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