A VAPOR-GROWN CARBON FIBER-REINFORCED BERYLLIUM COMPOSITE FOR PLASMA FACING MATERIAL

BERYLLIUM (BE) IS A CANDIDATE MATERIAL FOR DIVERTERS IN NUCLEAR FUSION REACTORS. HOWEVER, THE USE OF BE IS LIMITED BY ITS MODERATE THERMAL CONDUCTIVITY (218 W/M-K) AND BRITTLENESS, BOTH OF WHICH RESULT IN A LOW THERMAL SHOCK RESISTANCE. THE MODERATE THERMAL CONDUCTIVITY AND POOR MECHANICAL STRENGTH ALSO PLACE A LIMITATION ON THE THICKNESS OF THE BE COMPONENT, IN TURN LIMITING THE LIFETIME OF BE DIVERTER TILES. CARBON/CARBON COMPOSITES HAVING MUCH HIGHER THERMAL CONDUCTIVITY AND MECHANICAL STRENGTH HAVE BEEN DEVELOPED; HOWEVER, CARBON MATERIALS SUFFER FROM HIGH PHYSICAL AND CHEMICAL SPUTTERING EROSION RATES AND HIGH TRITIUM RETENTION. IT IS PLANNED TO DEVELOPED A GRAPHITE-FIBER-REINFORCED BE COMPOSITE WHICH WILL MANIFEST THE ADVANTAGES OF BOTH BE AND CARBON/CARBON COMPOSITES, AND WHICH WILL AMELIORATE THE DISADVANTAGES OF EITHER ONE. THE GRAPHITE FIBER PROPOSED FOR USE, CALLED VAPOR GROWN CARBON FIBER (VGCF), HAS THE HIGHEST THERMAL CONDUCTIVITY OF ALL CARBON FIBERS AVAILABLE, AS WELL AS LOWEST REACTIVITY. THE RESULTING MATERIAL IS ANTICIPATED TO EXHIBIT A THERMAL CONDUCTIVITY IN EXCESS OF 800 W/M-K BECAUSE OF THE USE OF VGCF, AND A MUCH HIGHER MECHANICAL STRENGTH BECAUSE OF THE COMPOSITE STRUCTURE. IN PHASE I A RAPID PRESSURE INFILTRATION TECHNIQUE WILL BE USED TO FABRICATE THE COMPOSITES. EFFORT WILL BE DIRECTED TOWARD EXAMINING INTERPHASE FORMATION, IF ANY, BETWEEN VGCF AND BE, AND DEMONSTRATING A VGCF/BE COMPOSITE WITH IMPROVED THERMAL AND MECHANICAL PROPERTIES. THERMAL CONDUCTIVITY, FRACTURE TOUGHNESS, AND MICROSTRUCTURAL ANALYSES WILL BE PERFORMED.