FFTG-P SI3N4 INFILTRATION FOR IMPROVED CERAMIC COMPOSITES

IN RESPONSE TO THE NEED FOR IMPROVED ENGINEERED MATERIALS FOR ADVANCED ELEVATED TEMPERATURE APPLICATIONS, ULTRAMET PROPOSES TO APPLY THE EXTENSIVE COMPOSITE PROCESSING EXPERIENCE, KNOWLEDGE BASE, AND UNDERSTANDING ACQUIRED IN SEVERAL CERAMIC AND COMPOSITE DEVELOPMENT PROGRAMS TO IMPROVING THE STATE-OFTHE-ART IN CHEMICAL VAPOR INFILTRATION (CVI) PROCESSING. SPECIFICALLY, ULTRAMET INTENDS TO COMBINE THE FORCED-FLOW THERMAL GRADIENT AND PULSE TECHNIQUES OF INFILTRATION, DIRECTLY RESULTING IN HIGHER QUALITY, MORE ECONOMICAL SILICON NITRIDE (SI3N4) COMPOSITES FOR USE IN IHPTET PHASE II AND III ENGINES. THE PROPOSED APPROACH HAS THE POTENTIAL TO SOLVE THE RECURRING DIFFICULTY OF MICROPOROSITY BETWEEN FIBERS DUE TO INADEQUATE INFILTRATION, ELIMINATE THE SUBSTANTIAL PERMEABILITY OCCURRING IN CURRENT STATE-OF-THE-ART MATERIALS, AND IMPROVE THE ECONOMICS OF COMPOSITE PROCESSING VIA VASTLY REDUCED PROCESSING TIMES. ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - THE DEVELOPMENT OF A DAMAGE-TOLERANT SI3N4 CERAMIC COMPOSITE WOULD PROVIDE A CRITICAL MILESTONE IN THE DEVELOPMENT OF HIGH-PERFORMANCE MATERIALS FOR A WIDE VARIET# OF AEROSPACE STRUCTURAL APPLICATIONS. THE USE OF ADVANCED CERAMIC COMPOSITES IN FUTURE PROPULSION DESIGNS WOULD ALSO PROVIDE SUBSTANTIAL EFFICIENCY PAYOFFS IN TERMS OF OPERATING TEMPERATURE, FUEL CONSUMPTION, AND WEIGHT. KEY WORDS - CERAMIC COMPOSITES, PULSED, SILICON NITRIDE (SI3N4), COMPOSITE PROCESSING, FORCED-FLOW, CHEMICAL VAPOR INFILTRATION (CVI), THERMAL GRADIENT.