US4776995A
Expired / Lapsed
US
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Method of making a structure
Assignee: Fiber Materials Inc
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Filing: 1986-08-22
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Granted: 1988-10-11
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Expires: 2006-08-22
Abstract
Abstract A carbonizable body is formed by infusing a plurality of preoxidized, preferably stabilized by known processing to have about 9 to 14 weight percent oxygen, polyacrylonitrile fibers in a polar liquid plasticizer, preferably water, capable of extracting a tarry leachate from the fibers. The infusion of the fibers in the plasticizer is continued for a sufficient time for a substantial amount of leachate to form on the surface of the fibers, and are then consolidated or diffusion-bonded to one another or other fibers, as by orienting the treated fibers in a mold and subjecting them to isostatic pressing at relatively low temperatures and pressure. Further processing of the consolidated fibers with appropriate heat treatment in an inert atmosphere will produce a carbonized bulk product with higher values of Young's modulus for the carbonized material than have been previously achieved at such carbonization temperatures. This carbonaceous product can be truly graphitized by subsequent heat treatment to obtain material with a modulus of at least 40x106 psi, and a tensile strength of at least 20x103 psi.
Inventors
- 👤 Daniel C. Nelson
- 👤 Roger T. Pepper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:00
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/71; C04B35/78; C04B35/80; C04B35/83; D; D01; D01F; D01F9/00; D01F9/08; D01F9/12; D01F9/14; D01F9/20; D01F9/21; D01F9/22
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
71 words
A method of forming a structure from preoxidized carbonaceous fibers, said method comprising the steps of: infusing a plurality of said fibers with a liquid plasticizer capable of extracting a tarry leachate from the infused fibers; maintaining said infused fibers in said plasticizer until said leachate forms a coating on the surfaces of said infused fibers; and diffusion bonding said plurality of infused fibers and leachate together into a carbonizable structure.
Claim 2
Independent Claim
71 words
A method of forming a structure from preoxidized carbonaceous fibers, said method comprising the steps of: infusing a plurality of said fibers with a liquid plasticizer capable of extracting a tarry leachate from the infused fibers; maintaining said infused fibers in said plasticizer until said leachate forms a coating on the surfaces of said infused fibers; and diffusion bonding said plurality of infused fibers and leachate together into a carbonizable structure.
Claim 3
Dependent Claim
19 words
A method as defined in claim 1 wherein said preoxidized fibers have about 9 to 14 weight percent oxygen.
Claim 4
Dependent Claim
22 words
A method as defined in claim 1 wherein said preoxidized fibers have oxidized densities of between about 1.35 and about 1.45 g/cc.
Claim 5
Dependent Claim
38 words
A method as defined in claim 1 wherein said fibers are infused until they have imbibed at least 5 and up to as much as 80 percent by weight of the plasticizer in terms of the fiber weight.
Claim 6
Dependent Claim
24 words
A method as defined in claim 1 wherein said diffusion bonding comprises a step of pressing said infused fibers and leachate in a mold.
Claim 7
Dependent Claim
23 words
A method as defined in claim 1 wherein said diffusion bonding comprises a step of hot isostatically pressing said infused fibers and leachate.
Claim 8
Dependent Claim
22 words
A method as defined in claim 1 wherein said diffusion bonding comprises a step of extrusion molding said infused fibers and leachate.
Claim 9
Independent Claim
44 words
A method as defined in claim including, prior to said diffusion bonding, a step of aligning a plurality of carbon fibers with said infused fibers and leachate, and diffusion bonding said plurality of carbon fibers together with said plurality of infused fibers and leachate.
Claim 10
Dependent Claim
15 words
A method as defined in claim 1 wherein said preoxidized carbonaceous fibers are polyacrylonitrile fibers.
Claim 11
Dependent Claim
12 words
A method as defined in claim 9 wherein said plasticizer is water.
Claim 12
Dependent Claim
14 words
A method as defined in claim 1 wherein said plasticizer is a polar liquid.
Claim 13
Dependent Claim
33 words
A method as defined in claim 1 wherein said plasticizer is an alcohol having from 2 to 10 carbon atoms per molecule and capable of extracting said tarry leachate from said infused fibers.
Claim 14
Dependent Claim
24 words
A method as defined in claim 12 wherein said alcohol has a boiling point in the range of about 100° C. to 300° C.
Claim 15
Dependent Claim
29 words
A method as defined in claim 12 wherein said step of infusing includes immersing said fibers in a bath of said alcohol at the boiling point of the latter.
Claim 16
Dependent Claim
30 words
A method as defined in claim 1 wherein said solvent is a polar liquid selected from the group consisting of water; ethylene carbonate; dimethyl sulfoxide; aliphatic alcohols; and aromatic alcohols.
Claim 17
Dependent Claim
28 words
A method as defined in claim 1 including the step of heating said carbonizable structure at a temperature and for a time sufficient to carbonize said carbonizable structure.
Claim 18
Dependent Claim
19 words
A method as defined in claim 16 wherein said steps of diffusion bonding and heating are carried out concurrently.
Claim 19
Dependent Claim
34 words
A method as defined in claim 16 wherein said steps of diffusion bonding and heating are carried out at temperatures as low as about 200° C. and pressures as low as about 2000 psi.
Claim 20
Dependent Claim
70 words
A method as defined in claim 16 wherein said steps of diffusion bonding and heating comprise hot pressing said plurality of infused fibers and leachate together at a pressure sufficient to consilidate said fibers and leachate into said carbonizable structure, and providing a temperature gradient at said pressure to raise the temperature of said structure to a level sufficient to pyrolize said fibers and leachate to carbonize said carbonizable structure.
Claim 21
Dependent Claim
13 words
A method as defined in claim 19 wherein said pressure is substantially isostatic.
Claim 22
Dependent Claim
20 words
A method as defined in claim 19 wherein cooling between consolidation and pyrolysis of said fibers and leachate is avoided.
Claim 23
Dependent Claim
81 words
A method as defined in claim 19 wherein, prior to said step of infusing, the method further comprises: laying up a plurality of said fibers substantially unidirectionaly; enclosing the laid-up fibers in an envelope to form a package; enclosing said package in a container capable of being drawn; drawing said container with the enclosed package to reduce the diameter of said package and increase the packing density of said fibers in said package up to as high as 80% by volume.
Claim 24
Dependent Claim
109 words
A method as defined in claim 22 including the steps of stripping said container from said package following drawing of said container; infusing the fibers in said package with said plasticizer; positioning the infused package in a receptacle; surrounding said package in said receptacle with a pressure transfer medium; positioning said receptacle with said package and transfer medium in the cavity of a pressure vessel; and wherein said steps of diffusion bonding and heating additionally comprise applying heat and pressure to said transfer medium in said receptacle at levels and for such time as is sufficient to consolidate, diffusion bond and carbonize said fibers and leachate in said package.
Claim 25
Dependent Claim
113 words
A method as defined in claim 19 wherein, prior to diffusion bonding, the method further comprises: loading said infused fibers and leachate into a collapsible receptacle; surrounding said infused fibers and leachate in said receptacle with a pressure transfer medium; positioning said receptacle and infused fibers in the cavity of a pressure vessel; and wherein said steps of diffusion bonding and heating additionally comprise applying heat and pressure to said transfer medium in said receptacle at levels and for such time as is sufficient to collapse said receptacle around said fibers and said leachate and hot press to thereby diffusion bond and carbonize said fibers and leachate into a substantially solid carbon structure.
Claim 26
Dependent Claim
35 words
A method as defined in claim 24 wherein said transfer medium is a refractory powder, or a metal that melts at a temperature below the temperature required to hot press said infused fibers and leachate.
Claim 27
Dependent Claim
38 words
A method as defined in claim 16 including the step of heat treating the carbonized structure in an inert atmosphere at a temperature and for a time sufficient to convert said carbonized structure to substantially a graphitic structure.
Claim 28
Dependent Claim
29 words
A method as defined in claim 26 wherein said heat treating step comprises gradual heating up to about 1400° C.-3200° C., to obtain maximum tensile strength and maximum stiffness.
Claim 29
Dependent Claim
57 words
A method as defined in claim 1 wherein said solvent is a polar liquid selected from the group consisting of water; ethylene carbonate; dimethyl sulfoxide; ethyl alcohol; n-pentyl alcohol; n-hexyl alcohol; n-heptyl alcohol; n-octyl alcohol; n-nonyl alcohol; n-decyl alcohol; tertiary-pentyl alcohol; cyclo-pentanol; cyclohexanol; ethylene glycol; propylene glycol; 1,3 propanediol; glycerol; benzyl alcohol; a-phenylethyl alcohol; and B-phenylethyl alcohol.
Claim 30
Dependent Claim
104 words
A process for hot isostatic pressing comminuted material in a pressure vessel, said process comprising the seps of loading said material into an envelope that will decompose at predetermined levels of temperature and pressure; placing said envelope with said material into a receptacle; surrounding said envelope in said receptacle with a pressure transfer medium; positioning said receptacle with said envelope and transfer medium in the cavity of said pressure vessel; applying heat and pressure to said transfer medium in said receptacle at or above said predetermined levels and for such time as is sufficient to compact said comminuted material into a substantially solid body.
Claim 31
Dependent Claim
104 words
A process for hot isostatic pressing comminuted material in a pressure vessel, said process comprising the seps of loading said material into an envelope that will decompose at predetermined levels of temperature and pressure; placing said envelope with said material into a receptacle; surrounding said envelope in said receptacle with a pressure transfer medium; positioning said receptacle with said envelope and transfer medium in the cavity of said pressure vessel; applying heat and pressure to said transfer medium in said receptacle at or above said predetermined levels and for such time as is sufficient to compact said comminuted material into a substantially solid body.
Claim 32
Dependent Claim
27 words
A process as defined in claim 29 wherein said transfer medium is a metal that melts at a temperature below the temperature required to consolidate said material.
Claim 33
Dependent Claim
14 words
A process as defined in claim 30 wherein said metal is an eutectic alloy.
Claim 34
Dependent Claim
14 words
A process as defined in claim 31 wherein said alloy is a bismuth-lead alloy.
Claim 35
Dependent Claim
13 words
A process as defined in claim 32 wherein said comminuted material is carbonaceous.
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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) | 1991-10-11 | 1992-04-11 | 1992-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-11 | 1996-04-11 | 1996-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-11 | 2000-04-11 | 2000-10-11 | $7700.00 | Window Closed / Lapsed |