Patent US5590895A successfully refreshed from Google Patents.
Patent US3625896A successfully refreshed from Google Patents.
US3625896A
Expired / Lapsed
US
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Thermal insulating powder for low-temperature systems and methods of making same
Assignee: AIRCRYO Inc A CA CORP
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Filing: 1968-06-07
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Granted: 1971-12-07
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Expires: 1988-06-07
Abstract
Abstract A thermal insulation powder for a cryogenic-evacuated insulation system, consists of an improved mixture of an opacifying powder and a low-density powder having high resistance to heat conduction. Ground expanded perlite is a preferred example of the opacifier, and pyrogenic silica is a preferred example of the low-density powder, the latter being in the form of agglomerates between the comparatively coarse particles of the perlite, and making up about one-half or more of the mixture by volume. This preferred mixture is compatible with oxygen. More effective interposition of the agglomerates between the opacifier particles for improving thermal insulation properties is achieved by impact-milling the mixture for a definite period of time.
Inventors
- 👤 Bradley S Kirk
- 👤 Chester B De Savigny
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 20:33
CPC Classifications
F; F17; F17C; F17C13/00; F17C13/001; C; C04; C04B; C04B20/00; C04B20/10; C04B20/1055; C04B30/00; F17C2203/00; F17C2203/03; Y; Y10; Y10S; Y10S428/00; Y10S428/92; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/31504; Y10T428/31652
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
19 words
The method as specified in claim 1 wherein the isolating carrier powder forms agglomerates about the respective opacifier particles.
Claim 2
Dependent Claim
14 words
The method as specified in claim 1 wherein the opacifIer consists essentially of perlite.
Claim 3
Dependent Claim
31 words
The method as specified in claim 1 wherein the opacifier is ground expanded perlite and the carrier is pyrogenic silica, and the mixture is impact-milled for a preselected period of time.
Claim 4
Dependent Claim
16 words
The method as specified in claim 1 wherein the opacifier consists essentially of porous carbonaceous particles.
Claim 5
Dependent Claim
16 words
The method as specified in claim 4 wherein the mixture is processed in a ball mill.
Claim 6
Dependent Claim
89 words
In a low temperature insulating system, a thermal insulating powder consisting of a milled mixture of an opacifier powder and a carrier powder, the opacifier being selected from the group of refractory materials consisting of inorganic silicates and expanded carbon, and the carrier constituting 5 to 40 percent of the mixture by weight and consisting of ultrafine refractory silica having very high resistance to heat transfer by conduction, and forming on the opacifier particles respectively, a stable encompassing envelope that physically and thermally isolates the particles from each other.
Claim 7
Dependent Claim
36 words
A thermal insulating powder as specified in claim 8 wherein the carrier envelope is in the form of stable agglomerates on the opacifier particle surfaces and interposed between the particles for preventing therebetween direct heat conduction.
Claim 8
Dependent Claim
15 words
A thermal insulating powder as specified in claim 8 wherein the carrier is pyrogenic silica.
Claim 9
Dependent Claim
16 words
A thermal insulating powder as specified in claim 8 wherein the opacifier is ground expanded perlite.
Claim 10
Dependent Claim
19 words
A thermal insulating powder as specified in claim 8 wherein the opacifier consists essentially of refractory expanded carbon particles.
Claim 11
Dependent Claim
113 words
In an evacuated insulation system, the method of insulating a vessel containing oxygen-rich material at cryogenic temperatures and having an outer jacket chamber subject to evacuation, which comprises: a. mixing an opacifier powder consisting essentially of ground expanded perlite with an ultrafine carrier powder consisting essentially of pyrogenic silica and constituting 5 to 40 percent of the mixture by weight, b. agitating under impact the mixture until the carrier powder is effectively interposed between the respective opacifier particles for physically and thermally isolating the particles from each other, c. filling the outer chamber with the resulting oxygen-compatible powder mixture, and d. reducing the chamber pressure to below approximately 1,000 microns of mercury absolute.
Claim 12
Dependent Claim
124 words
A thermal insulating powder for low-temperature systems consisting of a mixture of a dielectric opacifying powder consisting essentially of perlite and a carrier powder consisting essentially of finely divided silica, the opacifying powder being of particle size from 1 to 500 microns in major dimension, and dry bulk densities of from 0.1 to 0.8 grams per cubic centimeter, and the carrier powder being of refractory material formed as agglomerates having particles not more than 0.1 micron in major dimension and dry bulk densities of less than 0.1 grams per cubic centimeter and constituting between 5 and 40 percent by weight of the mixture, the carrier agglomerates being disposed in the mixture between opacifier particles for blocking heat transfer by conduction between the opacifier particles.
Claim 13
Dependent Claim
23 words
A thermal insulating powder as specified in claim 13 wherein the opacifier is ground expanded perlite and the carrier powder is pyrogenic silica.
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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) | 1974-12-06 | 1975-06-07 | 1975-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-06 | 1979-06-07 | 1979-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-06 | 1983-06-07 | 1983-12-07 | $7700.00 | Window Closed / Lapsed |