CARBON-CARBON COMPOSITES FOR THERMAL MANAGEMENT OF HIGH HEATING LOADS

THERE IS A NEED FOR LIGHTWEIGHT C/C COMPOSITES THAT CAN BE TAILORED TO MANAGE RAPIDLY GENERATED, VERY HIGH HEAT LOADS IN ELECTRONIC COMPONENTS AND SPACE AND MISSILE STRUCTURES FOR NAVSEA WEAPON SYSTEMS. THE INNOVATION IN THIS PROGRAM IS TO UTILIZE A HIGH CHAR YIELD MESOPHASE PITCH AND B(4)C DOPED PITCH AS MATRIX PRECURSORS TO FABRICATE C/C COMPOSITES FOR NAVSEA WEAPON SYSTEMS. C/C COMPOSITES OF VERY HIGH THERMAL CONDUCTIVITY WILL BE FABRICATED BY REINFORCING A MESOPHASE PITCH CARBON MATRIX WITH HIGHLY CONDUCTING P130X PITCH BASED CARBON FIBERS. THE JP130X FIBERS HAVE A THERMAL CONDUCTIVITY OF ABOUT 1140 W/M.K. MESOPHASE PITCH CARBON WILL ALIGN THE FIBERS TO PRODUCE A "SHEATH EFFECT" THAT SHOULD ENHANCE THE THERMAL CONDUCTIVITY AND MODULUS OF THE FIBER BUNDLES. ADDITION OF B(4)C TO A PITCH CARBON MATRIX SHOULD INCREASE THE THERMAL EXPANSIVITY AND ELASTIC MODULUS OF THE MATRIX. THE COMPOSITIES WILL BE HEATED ABOVE 2000 DEGREES C TO DEVELOP HIGH THERMAL CONDUCTIVITY IN THE MATRICES. A FINAL DENSIFICATION WITH CVI PYROCHARBON IS EXPECTED TO FURTHER INCREASE THE THERMAL CONDUCTIVITY OF THE COMPOSITIES AND IMPROVE THEIR STRENGTH AND TOUGHNESS. STRUCTURAL EVALUATION AND MEASUREMENT OF THERMAL AND MECHANICAL PROPERTIES WILL PROVDIE A DATA BASE. PHASE I RESEARCH IS EXPECTED TO DEMONSTRATE THE CONCEPTS AND PROVIDE A BASIS FOR PHASE II RESEARCH.