Processing of a New Class, Low-Cost Graphitic Microcellular C/C Composites using a One-Step Process

Strait pointing accuracy for the antenna and reflector of spacecraft requires structural materials with excellent stiffness and dimensional stability. Carbon-carbon (C/C) composites are prime materials for space applications because of their unique properties. Current C/C processing techniques are very expensive and time consuming. This Phase I research proposes a new class, low-cost graphitic microcellular C/C composites. The graphitic microcellular foams and microcellular C/C composites will be processed from mesophase pitch using the principle of thermodynamic instability. The blowing process will align the graphitic planes along the struts of the foamed matrix so that they are similar to graphite fibers. The micron to sub-micron bubbles will form a strong network between graphite fibers and foamed graphite matrix. Excellent specific stiffness and specific strength (higher than the conventional C/C), near zero therm; l expansion coefficients, no out-gassing make this class of microcellular C/C composites ideal for space structure applications. Samples with unidirectional fibers or woven fabrics as reinforcements will be processed; mechanical tests and SEM analyses will be performed to evaluate the material properties and morphology of the samples. The proposed processing technique could reduce the cost of C/C structures over 70%. The proposed low-cost microcellular C/C composites will have many potential commercial applications include satellite structures, propulsion system structures and leading edges of commercial supersonic aircraft, truck brake, high speed train brake, piston, battery electrode, printed wiring board and electronic packaging for thermoplanes, multi-layer PWBS, multichip modules, chip carriers and chip on board.