Process for production of alpha alumina bodies by sintering seeded boehmite made from alumina hydrates (USH0000189)
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Del.icio.us| IP.com Number | IPCOM000000189D |
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| Dated | Jan 6, 1987 UTC | ||
| Size | 3 page(s) (0.61 MB) | ||
| Disclosed by |
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Publication Summary
Inexpensive hydrates of alumina are used for the production of dense, submicron alumina bodies by conversion of the alumina hydrates to a soluble form which is then used to produce a boehmite gel. The boehmite gel, with very small particles of alpha alumina intimately dispersed therein is dried and fired to 1300.degree. C. to 1450.degree. C.| Country | United States |
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| Language | English (United States) |
| Related Person(s) |
(OWNER) Norton Company (INVENTOR) Bauer, Ralph (ATTORNEY) Franklin, Rufus M. (ATTORNEY) Chow, Frank S. |
| Related Document(s) |
(PATENT) USH000189
(PATENT) US01132737 (PATENT) US01354824 (PATENT) US01570353 (PATENT) US02006851 (PATENT) US02249761 (PATENT) US02595416 (PATENT) US02973245 (PATENT) US03480389 (PATENT) US03954957 (PATENT) US04032472 (PATAPP) US06/755510 |
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United States Patent |
USH0000189 |
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Bauer |
January 6, 1987 |
Process for production of alpha alumina bodies by sintering seeded boehmite made from alumina hydrates
Abstract
Inexpensive hydrates of alumina are used for the production of dense, submicron alumina bodies by conversion of the alumina hydrates to a soluble form which is then used to produce a boehmite gel. The boehmite gel, with very small particles of alpha alumina intimately dispersed therein is dried and fired to 1300.degree. C. to 1450.degree. C.
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Inventors: |
Bauer; Ralph (Niagara Falls, CA) |
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Assignee: |
Norton Company (Worcester, MA) |
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Appl. No.: |
06/755,510 |
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Filed: |
July 16, 1985 |
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Current U.S. Class: |
423/111 ; 423/626 |
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Current International Class: |
C04B 35/111 (20060101); C09K 3/14 (20060101); C01F 001/00 (); C01F 007/24 () |
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Field of Search: |
423/111,626 |
References Cited
U.S. Patent Documents
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1132737 |
March 1915 |
Schwahn |
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1354824 |
October 1920 |
Goldschmidt |
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1570353 |
January 1926 |
Jacobsson |
|
2006851 |
July 1935 |
Wied brauck et al. |
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2249761 |
July 1941 |
Hixson et al. |
|
2595416 |
May 1952 |
Schmerling |
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2973245 |
February 1961 |
Teter et al. |
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3480389 |
November 1969 |
Graulier |
|
3954957 |
May 1976 |
Koenig |
|
4032472 |
June 1977 |
McCallister |
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Primary Examiner: Terapane; John F.
Assistant Examiner: Jorgensen; Eric
Attorney, Agent or Firm:
Franklin; Rufus M. Chow; Frank S.
Claims
What is claimed is:
1. A method of making articles containing submicron alpha alumina in at least
one phase, comprising (1) dissolving alumina hydrate in nitric acid, (2)
converting the thus formed aluminum salt to boehmite having a crystal size
below 100.times.10.sup.-10 meters by nuetralization with ammonia, converting
said boehmite to a gel by acidification, and firing said gel in the presence of
at least 0.5% by weight of alpha alumina submicron seed particles to a temperature
less than 1450.degree. C. for a time such that the thus formed alpha alumina
phase has an average crystal size of less than 0.5.times.10.sup.-6 meters.
2. A method as in claim 1 in which the aqueous aluminous salt solution formed
in step (1) is neutralized with ammonium hydroxide to form boehmite having a
crystal size below 100.times.10.sup.-10 meters.
3. A method as in claim 1 in which the aluminum salt is a nitrate salt and is
dried and fired to increase the Al.sub.2 O.sub.3 lNO.sub.3 ratio to at least
2.5 to 1 and then autoclaved at 150.degree. to 300.degree. C. to produce
boehmite having a crystal size of less than 150.times.10.sup.-10 meters.
4. A method as in claim 1 in which the alumina hydrate is in the form of
naturally occuring ore.
5. A method as in claim 4 in which the ore is bauxite.
Description
BACKGROUND OF THE INVENTION
Recently it has been discovered that colloidal boehmite (alpha alumina
monohydrate) when formed into a gel or gel-like paste, and seeded with
ultrafine (less than 0.1 micron) alpha alumina particles, can be converted, by
relatively low temperature firing into alpha alumina bodies of extremely fine
crystal size (0.5...