THE CONVERSION OF GRAPHITE FIBER AND PREWOVEN ARCHITECTURES TO B4C FIBERS

CURRENT CERAMIC FIBERS LOSE STRENGTH RAPIDLY ABOVE 1000-1200 C AND HAVE VERY LOW CREEP RESISTANCE THUS LIMITING THEIR APPLICATIONS IN COMPOSITES FOR MANY ADVANCED MILITARY SYSTEMS. RECENT WORK HAS DEMONSTRATED THAT GRAPHITE FIBER (3-14) TOWS CAN BE CONVERTED TO SIC WHICH RETAINS NEARLY 100% OF THEIR STRENGTH TO 1500 C AND HAVE EXCELLENT CREEP RESISTANCE TO THE SAME TEMPERATURE. PRELIMINARY INVESTIGATIONS SHOW POTENTIAL FOR CONVERTING PREWOVEN GRAPHITE ARCHITECTURES TO SIC THUS OBVIATING THE NECESSITY TO WEAVE SIC FIBER. THIS PROGRAM PROPOSES TO UTILIZE THE CONCEPT OF CONVERTING GRAPHITE FIBER TO A CARBIDE TO DEVELOP BORON CARBIDE FIBER. THE CONVERSION CONCEPT WILL BE INVESTIGATED TO CONVERT PREWOVEN GRAPHITE ARCHITECTURES INTO SIC-B4C COMPOSITIONS AND B4C. BASED ON THE EXCELLENT STRENGTH AND CREEP PROPERTIES DEMONSTRATED FOR CONVERTING GRAPHITE TOWS TO SIC AND CONVERSION OF GRAPHITE CLOTH THE CONVERSION PROCESS PROMISES TO BECOME A VERY LOW COST MANUFACTURING METHOD TO PRODUCE CARBIDE FIBERS AND PREWOVEN ARCHITECTURES WHICH MAINTAIN HIGH STRENGTH AND CREEP RESISTANCE AT TEMPERATURES UP TO 1500 C. LOW COST CARBIDE FIBERS THAT ARE AVAILABLE IN PREWOVEN ARCHITECTURES AND WHICH MAINTAIN HIGH STRENGTH AND CREEP RESISTANCE AT TEMPERATURES UP TO 1500 C HAVE WIDESPREAD APPLICATIONS IN ADVANCED MILITARY SYSTEMS, AEROSPACE STRUCTURES, ENGINES, ENERGY CONVERSION, CUTTING TOOLS, WEAR PARTS AND SPORTS EQUIPMENT.