US4786548A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low loss radar window for reentry vehicle
Assignee: United States Department of the Air Force
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Filing: 1987-09-10
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Granted: 1988-11-22
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Expires: 2007-09-10
Abstract
Abstract A radar window for a reentry vehicle where the window is made of a composite material of boron nitride, silica, and boron nitride yarn. Silica in the range of 2 to 18 percent is the preferred range in the composite material and the boron nitride matrix ranges from 5 to 15 percent.
Inventors
- 👤 Thomas M. Place, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:14
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/583; Y; Y10; Y10T; Y10T428/00; Y10T428/30; Y10T442/00; Y10T442/30; Y10T442/3179; Y10T442/3195; Y10T442/3976
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
101 words
A composite material for use in a radar window of a reentry vehicle, said vehicle being exposed to temperatures in excess of 2200° C. upon reentry, said composite material comprising: a yarn of boron nitride, said yarn woven in a selective pattern to form a preform; boron nitride, said boron nitride impregnated throughout said preform to form a matrix composite; and silica, said silica being impregnated throughout said matrix composite, said silica being about 2 to about 20 weight percent of said composite material; whereby said composite material is substantially recession matched to a surrounding surface of tape-wrapped carbon phenolic materials.
Claim 2
Dependent Claim
101 words
A composite material for use in a radar window of a reentry vehicle, said vehicle being exposed to temperatures in excess of 2200° C. upon reentry, said composite material comprising: a yarn of boron nitride, said yarn woven in a selective pattern to form a preform; boron nitride, said boron nitride impregnated throughout said preform to form a matrix composite; and silica, said silica being impregnated throughout said matrix composite, said silica being about 2 to about 20 weight percent of said composite material; whereby said composite material is substantially recession matched to a surrounding surface of tape-wrapped carbon phenolic materials.
Claim 3
Dependent Claim
25 words
A composite material as defined in claim 1 wherein said boron nitride impregnated ranges from about 5 to about 15 weight percent of said composite.
Claim 4
Dependent Claim
32 words
A composite material as defined in claim 1 wherein said silica is in a range of about 2 to 5 weight percent, said range providing substantial recession match to tape-wrapped carbon phenolic.
Claim 5
Dependent Claim
25 words
A composite material as defined in claim 1 wherein said silica is about 18 weight percent, said silica providing minimum attenuation loss at X-band wavelengths.
Claim 6
Dependent Claim
35 words
A composite as defined in claim 1 wherein pressure impregnating of a high purity colloidal sol of silica at about 10,000 psi and sintering occurs in a range from 700° C. to about 800° C.
References Cited (Backward Citations)
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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) | 1991-11-22 | 1992-05-23 | 1992-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-22 | 1996-05-23 | 1996-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-22 | 2000-05-23 | 2000-11-22 | $7700.00 | Window Closed / Lapsed |