US4555393A
Expired / Lapsed
US
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Method for making carbon microfibers
Assignee: Bendix Corp
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Filing: 1984-06-21
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Granted: 1985-11-26
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Expires: 2004-06-21
Abstract
Abstract A continuous fiber composite having carbon microfibers dispersed in the resin filling the interstices between the continuous fibers to enhance the transverse properties of the composite. The carbon microfibers are made by soaking carbon fibers in an intercalating acid solution comprising a mixture of fuming nitric and sulfuric acid to weaken the intercrystallite bonds. Gentle stirring of solution separates the carbon microfibers from the host fibers. The microfibers are then separated from the intercalating acid solution and washed to remove the residual acid.
Inventors
- 👤 Ian W. Sorensen
- 👤 Robert S. Kiwak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:06
CPC Classifications
B; B29; B29C; B29C70/00; B29C70/04; B29C70/06; B29C70/08; B29C70/083
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
81 words
A method for making carbon microfibers comprising the steps of: immersing carbon fibers in an intercalating acid solution to weaken the intercrystal bonds betwen the crystallite planes of the carbon fibers; stirring said intercalating acid solution with the immersed carbon fibers to separate the weakened crystallite planes from the carbon fibers to form carbon microfibers; filtering said intercalating acid solution to separate said carbon microfibers from the acid solution; and rinsing said separated carbon microfibers to remove the residual intercalating acid.
Claim 2
Independent Claim
81 words
A method for making carbon microfibers comprising the steps of: immersing carbon fibers in an intercalating acid solution to weaken the intercrystal bonds betwen the crystallite planes of the carbon fibers; stirring said intercalating acid solution with the immersed carbon fibers to separate the weakened crystallite planes from the carbon fibers to form carbon microfibers; filtering said intercalating acid solution to separate said carbon microfibers from the acid solution; and rinsing said separated carbon microfibers to remove the residual intercalating acid.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein said intercalating acid solution is a mixture of nitric acid and sulfuric acid.
Claim 4
Dependent Claim
30 words
The method of claim 2 wherein said mixture comprises 50 to 70 percent fuming nitric acid and the remainder sulfuric acid at a temperature between 80° C. and 90° C.
Claim 5
Dependent Claim
25 words
The method of claim 2 wherein said mixture comprises 60 percent fuming nitric acid and 40 percent sulfuric acid at a temperature of 85° C.
References Cited (Backward Citations)
US4073869A
Cited
US4269876A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-11-25 | 1989-05-27 | 1989-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-25 | 1993-05-27 | 1993-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-25 | 1997-05-27 | 1997-11-26 | $7700.00 | Window Closed / Lapsed |