NOVEL PROCESSES FOR CHEMICAL VAPOR INFILTRATION OF STRUCTURAL CERAMIC COMPOSITES

THE PROPOSED PHASE I RESEARCH WILL EXAMINE TWO NOVEL PROCESSES FOR IMPROVING THE UNIFORMITY AND DENSITY OF CERAMIC MATRIX CHEMICAL VAPOR INFILTRATION (CVI). BOTH METHODS INVOLVE THE UNIFORM SELECTIVE DEPOSITION OF MATRIX MATERIAL STARTING AT THE FIBER MATRIX INTERFACE. ONE TECHNIQUE INVOLVES THE DEPOSITION OR ADDITION OF MATERIAL, ON THE FABRIC PREFORM, WHICH WILL SELECTIVELY COUPLE TO AN RF INDUCTION POWER SUPPLY. THIS SELECTIVE COUPLING SHOULD CAUSE LOCAL HEARING AND HENCE LOCAL DEPOSITION OF THE MATRIX MATERIAL. THE SECOND IMPROVED CVI PROCESS INVOLVES COATING OF MATERIALS, ON THE FABRIC PREFORM, WHICH WILL CATALYZE THE FORMATION OF THE MATRIX MATERIAL. THIS WILL ALLOW DEPOSITION OF THE MATRIX MATERIAL TO OCCUR AT LOWER TEMPERATURES AND THUS AVOID SOME OF THE UNDESIRABLE PREFERENTIAL SURFACE PORE CLOSURES WHICH INHIBIT COMPOSITE DENSIFICATION. THE PHASE I EFFORT WILLEVALUATE COMPOSITES FABRICATED BY BOTH OF THESE PROCESSES. EVALUATIONS WILL INCLUDE MICROSTRUCTURAL EXAMINATIONS AS WELL AS ROOM TEMPERATURE STRENGTH AND TOUGHNESS MEASUREMENTS OF COMPOSITES MADE WITH THE MOST PROMISING ADDITIVES. ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - THE PROPOSED IMPROVED CVI PROCESSES SHOULD LOWER PROCESSING COSTS FOR CIV INFILTRATED COMPOSITES. THESE LOWER COSTS WOULD RESULT FROM FEWER STEPS IN THE CVI PROCESS AND FEWER POST CVI PROCESSING STEPS TO FORM NET SHAPE COMPOSITES. THESE POTENTIAL ADVANTAGES OF THESE CVI PROCESSES MAKE THEM POTENTIALLY ATTRACTIVE PROCESSES FOR CERAMIC MATRIX COMPOSITE COMPONENT PRODUCTION FOR ENGINE AND AIRFRAME COMPONENTS