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Patent US4666873A successfully refreshed from Google Patents.
US4666873A
Expired / Lapsed
US
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Aluminum nitride-boron nitride composite article and method of making same
Assignee: Lockheed Martin Corp
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Filing: 1983-10-14
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Granted: 1987-05-19
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Expires: 2003-10-14
Abstract
Abstract A process for making a structural ceramic article, such as, an electromagnetic window, is disclosed, wherein the ceramic article is comprised of a densified mixture of not less than 50% by volume aluminum nitride and up to about 50% by volume boron nitride. The ceramic article of the present invention may be used as a shield or protective barrier such as an electromagnetic window for communication or detection devices on high speed transportation or delivery vehicles passing through extremely hostile environments, where it exhibits radar transparency, congruent vaporization kinetics, tailorable dielectric properties, improved thermal shock resistance, improved mechanical toughness and strength, improved spall resistance, improved recession rate, i.e. erosion rate and ablation rate, and high refractoriness.
Inventors
- 👤 John R. Morris, Jr.
- 👤 Richard A. Tanzilli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:18
CPC Classifications
H; H01; H01Q; H01Q1/00; H01Q1/42; B; B64; B64C; B64C1/00; B64C1/36; C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/581
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
63 words
A shaped article consisting of a ceramic material having a composition comprising: from about 0.01% to about 35% by volume of boron nitride, said boron nitride having a purity of at least about 95% by volume and substantially having a maximum particle size of about 10 microns; and aluminum nitride, said aluminum nitride having a purity of at least about 95% by volume.
Claim 2
Dependent Claim
63 words
A shaped article consisting of a ceramic material having a composition comprising: from about 0.01% to about 35% by volume of boron nitride, said boron nitride having a purity of at least about 95% by volume and substantially having a maximum particle size of about 10 microns; and aluminum nitride, said aluminum nitride having a purity of at least about 95% by volume.
Claim 3
Dependent Claim
22 words
The article according to claim 1 wherein said boron nitride and said aluminum nitride are at least about 98% by volume pure.
Claim 4
Dependent Claim
18 words
The article according to claim 1 further comprising up to about 2% by volume of an oxidizing agent.
Claim 5
Dependent Claim
24 words
The article according to claim 3 wherein said oxidizing agent is selected from the group consisting of aluminum oxide, boron oxide, and silicon dioxide.
Claim 6
Dependent Claim
64 words
A window transparent to electromagnetic radiation in a predetermined frequency spectrum, said window consisting of a ceramic material having a composition comprising: from about 0.01% to about 35% by volume a dispersion of boron nitride, said boron nitride having a purity of at least about 95% by volume; and aluminum nitride, said aluminum nitride having a purity of at least about 95% by volume.
Claim 7
Dependent Claim
64 words
A window transparent to electromagnetic radiation in a predetermined frequency spectrum, said window consisting of a ceramic material having a composition comprising: from about 0.01% to about 35% by volume a dispersion of boron nitride, said boron nitride having a purity of at least about 95% by volume; and aluminum nitride, said aluminum nitride having a purity of at least about 95% by volume.
Claim 8
Dependent Claim
20 words
A window according to claim 5 wherein said boron nitride substantially has a maximum particle size of about 10 microns.
Claim 9
Dependent Claim
22 words
A window according to claim 5 wherein said boron nitride and said aluminum nitride are at least about 98% by volume pure.
Claim 10
Dependent Claim
18 words
A window according to claim 5 further comprising up to about 2% by volume of an oxidizing agent.
Claim 11
Dependent Claim
24 words
A window according to claim 8 wherein said oxidizing agent is selected from the group consisting of aluminum oxide, boron oxide, and silicon dioxide.
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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) | 1990-05-18 | 1990-11-17 | 1991-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-18 | 1994-11-17 | 1995-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-18 | 1998-11-17 | 1999-05-19 | $7700.00 | Window Closed / Lapsed |