Transparent alumina microspheres
CA 1286479 C · Owner: Minnesota Mining And Manufacturing Company · Inventors: Fellows, Benjamin T.; Leedecke, Charles J.; Bescup, Terrance L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Procedure for making Al2O3 spheroids 600, micrometers in diameter or less, utilizes an AlOOH sol containing 0.25% weight percent MgO (in the form of Mg(NO3)2.6H2O) and HNO3. The sol is dispersed into droplets in a particle forming fluid (e.g. 2-ethylhexanol) where gelling occurs. The gelled spheroids are collected dried and pre-fired in air at temperatures less than 1,200°C for up to about 12 hours. The dried and prefired beads are fired in a 2-step process at temperatures of about 1,850-1,950°C in the following sequence: a first dry oxygen firing for about ten minutes followed by a wet hydrogen firing for up to 350 minutes. Reasonably transparent microspheres having crystallites in the …
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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
- Granted July 23, 1991. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 23, 2008.
- 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.