Abstract Organic fibers are partially carbonized to match their volume shrinkage upon complete carbonization to that of the resin matrix. Improved carbonized composite parts are manufactured with high reliability and low failure rates despite high adhesion between initially partially carbonized fiber surfaces and encompassing matrix resins during temperature cycling occurring in processing. Partially carbonized fibers having active surface components are firmly adhered to matrices comprising flexible but self-supporting thermosetting resin materials of carbonizable character. A composite part of complex shape and thin wall sections may be formed from these materials by molding under pressure and temperature. The flexible characteristic of the resin is maintained through the molding phase and permits differential shrinkage to occur without fabric-resin separation. The molded part is however self supporting and the resin matrix may thereafter be partially carbonized at an appropriate temperature level. Following this the entire part may be graphitized at an elevated temperature in an inert atmosphere, followed by infiltration and reimpregnation if desired.
The invention as set forth in claim 1 above, wherein the matrix consists essentially of a resin.
Claim 2
Dependent Claim
32 words
The invention as set forth in claim 1 above, wherein said thermosetting resin comprises a furfuryl alcohol copolymer forming a chemical carbon-to-carbon bond with the fiber or fabric after carbonization is completed.
Claim 3
Dependent Claim
19 words
The invention as set forth in claim 1 above, wherein the matrix comprises filler particles contained in a resin.
Claim 4
Dependent Claim
16 words
The invention as set forth in claim 4 above, wherein said filler particles comprise graphite particles.
Claim 5
Dependent Claim
27 words
The invention as set forth in claim 1 above, wherein the precursor is a polyacrylonitrile material and the partial carbonizing temperature is approximately 800* to 900* F.
Claim 6
Dependent Claim
25 words
The invention as set forth in claim 1 above, wherein the precursor is a rayon material, and the partial carbonizing temperature is approximately 1,600* F.
Claim 7
Dependent Claim
47 words
The invention as set forth in claim 1 above, wherein the partial carbonizing comprises heating the fiber or fabric to approximately 900* F. in an inert atmosphere and the graphitizing comprises heating the shaped article to a temperature in excess of 3,500* F. in an inert atmosphere.
Claim 8
Dependent Claim
22 words
The invention as set forth in claim 1, further including the step of pyrolytically infiltrating the carbonized composite article with carbon material.