EP0408771B1
Expired / Lapsed
EP
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Alumina ceramic, abrasive material, and production thereof
Assignee: Resonac Holdings Corp
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Filing: 1990-02-01
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Granted: 1993-08-04
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Expires: 2010-02-01
Abstract
Abstract An alumina ceramic as an abrasive material for abrasive grain, grindstone, abrasive cloth, abrasive paper etc., having high strength and toughness and excellent grinding characteristic, can be produced by controlling the density to be at least 95% of the theoretical value, the hardness to be at least 2,000 kg/mm2, and the crystal size to be at most 0.2 νm on the average. The method for producing the ceramic comprises effecting the gelation of an alumina sol containing minute α-alumina crystal grains, rapidly heating the gel from 900°C to 1,100°C within 90 sec, and holding it at 1,000 to 1,300°C for a given time.
Inventors
- 👤 Tetsuo Showa Denko Kabushiki Kaisha Hatanaka
- 👤 Tadashi Showa Denko Kabushiki Kaisha Hiraiwa
- 👤 Minoru Showa Denko Kabushiki Kaisha Matsukura
- 👤 Norimichi Showa Denko Kabushiki Kaisha Aoki
- 👤 Shoichi Showa Denko Kabushiki Kaisha Imai
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 06:33
CPC Classifications
C; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C09K3/1418; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
55 words
An α-alumina-based ceramics material comprising crystals of a particle diameter of no greater than 0.2 µm on an average or a particle diameter of substantially no greater than 0.2 µm, and having a density of no lower than 95% of a theoretical density and a Vickers hardness of no lower than 19,62 GPa (2,000 kg/mm²).
Claim 2
Dependent Claim
12 words
An alumina-based abrasive grain comprising said ceramics material described in Claim 1.
Claim 3
Dependent Claim
15 words
A grinding wheel or coated abrasive using said alumina-based abrasive grain described in Claim 2.
Claim 4
Dependent Claim
42 words
A ceramics material as described in Claim 1, wherein said ceramics material contains no more than 20 wt% of at least one member of oxides of Fe, Cu, Ni, Ba, Be, Mg, Cr, Si, Mn, Zr, Ti, Ca, V, Ga and Rh.
Claim 5
Dependent Claim
12 words
An alumina-based abrasive grain comprising said ceramics material described in Claim 4.
Claim 6
Dependent Claim
15 words
A grinding wheel or coated abrasive using said alumina-based abrasive grain described in Claim 5.
Claim 7
Independent Claim
98 words
A method for the production of an α-alumina-based ceramics material or abrasive grains made of crystals of a particle diameter of no greater than 0.2 µm on an average or a particle diameter of substantially no greater than 0.2 µm by gelling an alumina sol containing fine α-alumina crystal grains, heating the gelled product with setting up a maximum temperature in a range of from 1,100 to 1,300°C, with time of temperature elevation from 900 to 1,100°C being set up to no longer than 90 seconds, and then retaining it at a temperature of from 1,000 to 1,300°C.
Claim 8
Dependent Claim
55 words
A method as described in Claim 7, wherein said ceramics material contains in said ceramics material at least one member of oxides of Fe, Cu, Ni, Ba, Be, Mg, Cr, Si, Mn, Zr, Ti, Ca, V, Ga and Rh, and precursors thereof in an amount of no more than 20 wt% in terms of oxide.
Claim 9
Independent Claim
129 words
A method for the production of an α-alumina-based ceramics material or abrasive grain made of crystals of a particle diameter of no greater than 0.2 µm on an average or a particle diameter of substantially no greater than 0.2 µm by a two-step sintering method comprising gelling an alumina sol containing fine α-alumina crystal grains, heating the gelled product with setting up a maximum temperature in a range of from 1,100 to 1,300°C, with time of temperature elevation from 900 to 1,100°C being set up to no longer than 90 seconds, retaining the product at a temperature in a range of from 1,100 to 1,300°C for from 30 seconds to 10 minutes and further retaining it at a temperature of from 1,000 to 1,200°C for 1 to 100 hours.
Claim 10
Dependent Claim
55 words
A method as described in Claim 9, wherein said ceramics material contains in said ceramics material at least one member of oxides of Fe, Cu, Ni, Ba, Be, Mg, Cr, Si, Mn, Zr, Ti, Ca, V, Ga and Rh, and precursors thereof in an amount of no more than 20 wt% in terms of oxide.
References Cited (Backward Citations)
US4623364A
Cited
JPS6411183A
Cited
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