Plastic and nonmetallic article shaping or treating: processes – Carbonizing to form article
Patent
1989-02-28
1991-01-22
Thurlow, Jeffery
Plastic and nonmetallic article shaping or treating: processes
Carbonizing to form article
264 82, 264136, 264137, 4234474, 4234476, 423449, C01B 3102
Patent
active
049869434
ABSTRACT:
An oxidation process for stabilization of pitch-based matrices in the fabrication of carbon-carbon composites. By oxidizing a fiber preform impregnated with petroleum-derived mesophase pitch at temperatures in the range of 190.degree. to 300.degree. C. for periods of the order of ten hours, the matrix is fixed in place within the preform so that softening, bloating, and expulsion of the matrix are avoided when the body is carbonized. The invention can also be practiced to increase the carbon yield upon carbonization. Sufficient access porosity must exist in the matrix to permit oxidation throughout the composite body; this is normally formed in a preform due to the mismatch in thermal expansivities of fiber and matrix. Also, the softening point of the pitch must be above the oxidation temperature; this need can be met for most mesophase pitches. The process of oxidation stabilization can also be applied to isotropic pitches if these requirements are met, and to pitch derived from coal tar or other sources if the pitch is susceptible to oxidation. This invention may be practiced to reduce the time and cost of pitch-based composite fabrication, to eliminate the need for high-pressure carbonization, and thus to make pitch-based fabrication practical for large composite structures.
REFERENCES:
patent: 3476703 (1969-11-01), Wadsworth
patent: 3720575 (1973-03-01), Cowlard
patent: 4396663 (1983-08-01), Mitchell et al.
patent: 4490201 (1984-12-01), Leeds
Sheaffer Patrick M.
White Jack L.
Burke William J.
Tentoni Leo B.
The Aerospace Corporation
Thurlow Jeffery
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