THE RAPID GROWTH AND HARVESTING OF SIC WHISKERS FROM COMPOSITE PARTICLES

THE USE OF WHISKERS IN METALS AND CERAMICS IS WELL ESTABLISHED AND DESTINED TO PLAY A MAJOR ROLE IN ADVANCED HIGH TECHNOLOGY MATERIALS APPLICATIONS. THE AVAILABILITY AND COST OF WHISKERS SUCH AS SILICON CARBIDE (SIC) IS A KEY TO THE ECONOMIC PRODUCTION AND WIDESPREAD USE OF ADVANCED COMPOSITE MATERIALS. CURRENTLY, WHISKERS ARE BATCH GROWN IN 6- TO 10-HOUR CYCLES USING STAINLESS STEEL POWDER AS A SEED CATALYST TO PROMOTE A VAPOR-LIQUID-SOLID (VLS) GROWTH MECHANISM. THE LENGTH AND DIAMETER (1/D) CONTROL OF WHISKERGROWTH IS RANDOM, WITH VERY LITTLE PROCESS CONTROL TO PRODUCE CONTROLLED WHISKER SIZES. ADVANCED COMPOSITES IDEALLY REQUIRE A CONTROLLED 1/D WHISKER TO PRODUCE HIGH PERFORMANCE AND RELIABLE COMPOSITES. AFTER A BATCH GROWTH CYCLE, TEDIOUS AND MULTIPLE STEP HARVESTING IS REQUIRED TO SEPARATE THE WHISKERS FROM POWDER GROWTH AND CATALYST. THE BATCH PROCESSING AND HARVESTING RESULTS IN HIGH COST WHISKERS WITH A PROJECTED PRODUCTION COST OF AROUND $100/LB.THERE IS ONLY ONE MAJOR U.S. WHISKER PRODUCER AND SEVERAL JAPANESE PRODUCERS CURRENTLY MARKETING WHISKERS IN THE UNITED STATES AT ABOUT $250/LB. THIS PROGRAM PLANS TO INVESTIGATE A CONTINUOUS RAPID GROWTH PROCESS FROM A COMPOSITE CATALYZED PARTICLE WITH IN SITU CONTINUOUS GAS TRANSPORT HARVESTING WITH THE POTENTIAL TO PRODUCE SIC WHISKERS AT NEAR THE COST OF SIC POWDER.