Glass manufacturing – Processes – With shaping of particulate material and subsequent fusing...
Patent
1976-05-10
1978-02-07
Lindsay, Jr., Robert L.
Glass manufacturing
Processes
With shaping of particulate material and subsequent fusing...
65 32, 65 33, 65DIG8, C03B 2320, C03B 3200
Patent
active
040724891
ABSTRACT:
A process is disclosed for making vitreous silica crucibles of exceptional high quality for use in the growing of a silicon crystal from molten silicon. The crucibles are formed from fine particles of high purity fused silica by slip casting or other suitable process, are dried and fired to provide a rigid porous body, and are thereafter sintered to a high density, preferably to the transparent state. The invention solves the problem of spalling, blistering and cracking during crystal growing and the resulting contamination of the molten silicon, which has long plagued the industry, by eliminating water from the fused silica particles before the porous body is sintered to the transparent state. Said body is thoroughly dried in a vacuum furnace at a high temperature and at a sub-atmospheric pressure low enough to remove the chemically bound water which cannot be removed by heat alone. The crucibles of this invention retain their transparency and high quality without spalling or introducing microscopic particles of silica into the silicon, thereby making it possible to grow a silicon crystal of highest quality without dislocations and imperfections due to contamination by said particles.
REFERENCES:
patent: 2982053 (1961-05-01), Elmer
patent: 3261676 (1966-07-01), Morelock
patent: 3837825 (1974-09-01), Loxley et al.
patent: 3850602 (1974-11-01), Bruning
patent: 3853520 (1974-12-01), Rau
Barber Walter G.
Combs Walter W.
Loxley Ted A.
Webb John M.
Lindsay, Jr. Robert L.
Miga Frank W.
Sherwood Refractories Inc.
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