VAPOR GROWN CARBON FIBERS-REINFORCED BERYLLIUM COMPOSITE

BERYLLIUM IS A CANDIDATE MATERIAL FOR APPLICATIONS REQUIRING LOW DENSITY, STRENGTH, AND/OR THERMAL PERFORMANCE, SUCH AS SPACE STRUCTURES, HEAT SHIELDS, RADIATORS, AND ELECTRONICS. HOWEVER, THE USE OF BERYLLIUM IS LIMITED BY ITS MODERATE THERMAL CONDUCTIVITY AND BRITTLENESS, BOTH OF WHICH RESULT IN LOW THERMAL SHOCK FRACTURE TOUGHNESS. THIS ALSO PLACES A LIMITATION ON THE THICKNESS OF A BERYLLIUM COMPONENT, WHICH CAN IMPOSE LIMITS IN LIFETIME FOR SOME APPLICATIONS. A GRAPHITE-FIBER-REINFORCED BERYLLIUM COMPOSITE WHICH MANIFESTS THE ADVANTAGES OF BOTH BERYLLIUM AND CARBON/CARBON COMPOSITES, AND WHICH AMELIORATES THE DISADVANTAGES OF EITHER ONE, IS BEING DEVELOPED. A PRELIMINARY EXPERIMENT SUGGESTED THE ADVANTAGE OF USING HIGHLY GRAPHITIC FIBER TO REDUCE INTERFACE REACTION. THE GRAPHITE FIBER IS VAPOR GROWN CARBON FIBER (VGCF), WHICH IS THE MOST GRAPHITIC FIBER KNOWN TO BE AVAILABLE. THE USE OF COATINGS ON VGCF IS BEING INVESTIGATED FOR FURTHER REDUCING OR AVOIDING ANY INTERFACIAL REACTION. A RAPID PRESSURE INFILTRATION TECHNIQUE WILL BE USED TO FABRICATE THE COMPOSITES. THE EFFORTS ARE BEING DIRECTED TOWARD EXAMINING THE INTERFACES BETWEEN ANY TWO DISSIMILAR MATERIALS AND DEMONSTRATING A VGCF/BE COMPOSITE WITH IMPROVED THERMAL AND MECHANICAL PROPERTIES.