US4783430A
Expired / Lapsed
US
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Process of making high purity aluminum nitride
Assignee: Osram Sylvania Inc
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Filing: 1986-04-25
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Granted: 1988-11-08
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Expires: 2006-04-25
Abstract
Abstract A high purity aluminum nitride is made by precipitating (CH 3 ) 3 Al:NH 3 , washing it with hexane and pyrolyzing it to AlN. The precipitation is obtained by reacting a hexane solution of trimethyl aluminum with high purity anhydrous NH 3 (g), or by reaction Al(CH 3 ) 3 (g) and NH 3 (g) in a hexane solution, or by reacting Al(CH 3 ) 3 (g ) with NH 3 (1). The resulitng AlN is very pure and a density of 91.3% of theoretical has been achieved by pressing and sintering a pellet made from it as compared to a 89% theoretical density obtained by pressing and sintering a pellet made from commercial AlN powder.
Inventors
- 👤 Sophia R. Su
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:53
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/072; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/581; C01P; C01P2006/00; C01P2006/80
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
96 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting a hydrocarbon solution of trimethyl aluminum with high purity anhydrous NH 3 (g) forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the hydrocarbon solution; Step 3--redissolving the precipitate formed in step 1 in the hydrocarbon solution; Step 4--evaporating the hydrocarbon solution from step 3 with a nitrogen stream to form a white crystalline material; and Step 5--pyrolyzing the white crystalline material form step 4 in an inert atmosphere to form high purity aluminum nitride.
Claim 2
Independent Claim
96 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting a hydrocarbon solution of trimethyl aluminum with high purity anhydrous NH 3 (g) forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the hydrocarbon solution; Step 3--redissolving the precipitate formed in step 1 in the hydrocarbon solution; Step 4--evaporating the hydrocarbon solution from step 3 with a nitrogen stream to form a white crystalline material; and Step 5--pyrolyzing the white crystalline material form step 4 in an inert atmosphere to form high purity aluminum nitride.
Claim 3
Dependent Claim
25 words
A method in accordance with claim 1 wherein said pyrolysis comprises heating the product from step 4 to about 900° C. in an inert atmosphere.
Claim 4
Dependent Claim
15 words
A method in accordance with claim 1 wherein said hydrocarbon solution comprises a hexane solution.
Claim 5
Independent Claim
97 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting Al(CH 3 ) 3 (g) and NH 3 (g) with a hydrocarbon solution forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the hydrocarbon solution; Step 3--redissolving the precipitate formed in step 1 in the hydrocarbon solution; Step 4--evaporating the hydrocarbon solution from step 3 with a nitrogen stream to form a white crystalline material; and Step 5--pyrolyzing the washed white crystalline material from step 4 in an inert atmosphere to form high purity aluminum nitride.
Claim 6
Independent Claim
97 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting Al(CH 3 ) 3 (g) and NH 3 (g) with a hydrocarbon solution forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the hydrocarbon solution; Step 3--redissolving the precipitate formed in step 1 in the hydrocarbon solution; Step 4--evaporating the hydrocarbon solution from step 3 with a nitrogen stream to form a white crystalline material; and Step 5--pyrolyzing the washed white crystalline material from step 4 in an inert atmosphere to form high purity aluminum nitride.
Claim 7
Dependent Claim
15 words
A method in accordance with claim 4 wherein said hydrocarbon solution comprises a hexane solution.
Claim 8
Independent Claim
88 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting Al(CH 3 ) 3 (g) with NH 3 (1) forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the NH 3 (1) ; Step 3--redissolving the precipitate formed from step 1; Step 4--evaporating the NH 3 (1) with a nitrogen stream to form a white crystalline material; and Step 5--pyrolyzing the white crystalline material from step 4 in an inert atmosphere to form high purity aluminum nitride.
Claim 9
Independent Claim
88 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting Al(CH 3 ) 3 (g) with NH 3 (1) forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the NH 3 (1) ; Step 3--redissolving the precipitate formed from step 1; Step 4--evaporating the NH 3 (1) with a nitrogen stream to form a white crystalline material; and Step 5--pyrolyzing the white crystalline material from step 4 in an inert atmosphere to form high purity aluminum nitride.
Claim 10
Independent Claim
138 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting a hydrogen carbon solution of trimethyl aluminum with high purity anhydrous NH 3 (g) forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the hydrocarbon solution; Step 3--redissolving the precipitate formed in step 1 in the hydrocarbon solution; Step 4--evaporating the hydrocarbon solution from step 3 with a nitrogen stream to form a white crystalline material; Step 5--pyrolyzing the white crystalline material from step 4 in an inert atmosphere to form high purity aluminum nitride; Step 6--pressing the product from step 5 to form a pressed article; and Step 7--sintering the product from step 6 at a temperature of about 1850° C. to form a densified aluminum nitride article having a theoretical density of at least 91.3%.
Claim 11
Independent Claim
138 words
A method of making high purity aluminum nitride comprising the following steps: Step 1--contacting a hydrogen carbon solution of trimethyl aluminum with high purity anhydrous NH 3 (g) forming a precipitate and generating heat; Step 2--removing the heat generated in step 1 by cooling the hydrocarbon solution; Step 3--redissolving the precipitate formed in step 1 in the hydrocarbon solution; Step 4--evaporating the hydrocarbon solution from step 3 with a nitrogen stream to form a white crystalline material; Step 5--pyrolyzing the white crystalline material from step 4 in an inert atmosphere to form high purity aluminum nitride; Step 6--pressing the product from step 5 to form a pressed article; and Step 7--sintering the product from step 6 at a temperature of about 1850° C. to form a densified aluminum nitride article having a theoretical density of at least 91.3%.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-08 | 1992-05-09 | 1992-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-08 | 1996-05-09 | 1996-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-08 | 2000-05-09 | 2000-11-08 | $7700.00 | Window Closed / Lapsed |