Process for making silicon nitride whisker
CA 2000457 C · Owner: Toshiba Ceramics Co. Ltd. · Inventors: Imai, Isao; Ishii, Toshitsugu; Sueyoshi, Kouichi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Silica powder or a mixture of silica powder and silicon nitride whisker are heated at a temperature ranging from 800°C to 1,700°C in a gaseous mixture of ammonia gas (NH3) and hydrocarbon gas (CmHn) so as to produce silicon nitride whisker. The gaseous mixture flows at the rate of 10 mm/sec or less. The ratio of the ammonia to the hydrocarbon expressed as NH3/CH4 ranges from 0.5:1 to 2000:1 by volume. The silica powder is preferably mixed with at least one of six catalysts: transition metals; alkali metals: alkaline earth metals: halides of transition metals; halide; of alkali metals; and alkaline earth metals. One mol part of the silica powder is mixed with 0.001 - 1.0 mol part of the …
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed October 11, 1989 and granted October 1, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended October 11, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 11, 2011.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.