US4780299A
Expired / Lapsed
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Method for producing aluminum nitride powder
Assignee: JFE Steel Corp
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Filing: 1987-11-23
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Granted: 1988-10-25
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Expires: 2007-11-23
Abstract
Abstract A method for producing an aluminum nitride powder of superior sinterability of which steps are providing an aqueous boehmite sol having a pH of 1.2 to 4.5, mixing a carbon source material to the sol and drying the mixture. The mixture is sintered in a non-oxidizing atmosphere containing nitrogen or in a nitrogen atmosphere and finally decarbonized to obtain an aluminum nitride powder. The carbon source material is preferably a mixture of an organic carbon source material and a solid carbon powder. A predetermined amount of alpha-alumina may be added to the mixture.
Inventors
- 👤 Masato Kumagai
- 👤 Yutaka Yoshii
- 👤 Ryoji Uchimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:57
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/072; C01B21/0726; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/581; C01P; C01P2004/00; C01P2004/51; C01P2004/52; C01P2004/60; C01P2004/61
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
68 words
A method for producing aluminum nitride powder which comprises adding a boehmite powder to an aqueous medium, adjusting the resulting dispersion to a pH of 1.2 to 4.5 to obtain a boehmite sol, mixing the boehmite sol with a carbon source material, drying the mixture, sintering the dried mixture in a non-oxidizing atmosphere containing a nitrogen gas, and decarbonizing the sintered product to obtain an aluminum nitride powder.
Claim 2
Independent Claim
68 words
A method for producing aluminum nitride powder which comprises adding a boehmite powder to an aqueous medium, adjusting the resulting dispersion to a pH of 1.2 to 4.5 to obtain a boehmite sol, mixing the boehmite sol with a carbon source material, drying the mixture, sintering the dried mixture in a non-oxidizing atmosphere containing a nitrogen gas, and decarbonizing the sintered product to obtain an aluminum nitride powder.
Claim 3
Dependent Claim
29 words
A method for producing an aluminum nitride powder according to claim 1, wherein said carbon source material is mixed with the boehmite sol after dispersion in an aqueous medium.
Claim 4
Dependent Claim
28 words
A method for producing an aluminum nitride powder according to claim 1, wherein, prior to the drying, the mixtures is solidified in a uniformly mixed state and gelled.
Claim 5
Dependent Claim
29 words
A method for producing an aluminum nitride powder according to claim 1, wherein a sintering agent is added to the boehmite sol, the carbon dispersion or the mixture thereof.
Claim 6
Dependent Claim
35 words
A method for producing an aluminum nitride powder according to claim 1, further comprising adding from 0.01 to 50 wt% of alpha-alumina powder to the mixture of said boehmite sol and the carbon source material.
Claim 7
Dependent Claim
31 words
A method for producing an aluminum nitride powder according to claim 1, wherein said carbon source material is a mixture of an organic carbon source material and a solid carbon powder.
Claim 8
Dependent Claim
42 words
A method for producing an aluminum nitride powder according to claim 6, wherein a mixing ratio by weight of the carbon derived from said organic carbon source material to the solid carbon powder is in the range of from 0.05:1 to 0.5:1.
Claim 9
Dependent Claim
49 words
A method for producing an aluminum nitride powder according to claim 6, wherein a ratio by weight of the total amount of the carbon derived from said organic carbon source material and the solid carbon powder to the boehmite powder is in the range of from 0.4:1 to 3.0:1.
Claim 10
Dependent Claim
26 words
A method for producing an aluminum nitride powder according to claim 6, wherein the solid carbon powder has a size of not larger than 0.5 microns.
Claim 11
Dependent Claim
40 words
A method for producing an aluminum nitride powder according to claim 6, further comprising adding from 0.01 to 50 wt% of alpha-alumina powder, based on the boehmite powder, to the mixture of the boehmite sol and the carbon source material.
References Cited (Backward Citations)
JPS61183108A
Cited
JPS6278103A
Cited
JPS62100405A
Cited
JPS62132710A
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JPS62167208A
Cited
JPS62182164A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-25 | 1992-04-25 | 1992-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-25 | 1996-04-25 | 1996-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-25 | 2000-04-25 | 2000-10-25 | $7700.00 | Window Closed / Lapsed |