The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 28, 1995
Filed:
Mar. 24, 1994
Timothy A Jennett, Cleveland, GB;
Patrick D Harmsworth, Cleveland, GB;
Dave Martin, Cleveland, GB;
Anthony W Ellison, Cleveland, GB;
Tioxide Specialties Limited, London, GB;
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%