MOCVD OF CONTINUOUSLY REINFORCED CARBIDES

HYPERSONIC AND SUPERSONIC SPEEDS ARE FEASIBLE DUE TO ADVANCES IN AEROSPACE ENGINEERING, VEHICLE DESIGN, AND PROPULSION TECHNOLOGY. THE EFFICIENCIES, RELIABILITY, AND ULTIMATE POTENTIAL OF AIR BREATHING PROPULSION SYSTEMS HINGE UPON NEW MATERIALS THAT CAN SURVIVE THE HARSH COMBUSTION ENVIRONMENTS. HAFNIUM AND ZIRCONIUM CARBIDE AND BORIDE MATRICES ARE CANDIDATE MATERIALS SYSTEMS, BUT ONLY IF MANUFACTURING METHODS CAN BE DEVELOPED. CHEMICAL VAPOR INFILTRATION (CVI) PROCESSES BASED UPON THE DECOMPOSITION OF THE METAL HALIDES SUFFER FROM NON-STOICHIOMETRIC DEPOSITS, INCOMPLETE INFILTRATION, AND LOW DENSITY. THE DEPOSITION KINETICS OF ORGANOMETALLAIC CHEMICAL VAPOR DEPOSITION (OMCVD) BASED PROCESSED MAY BE CONTROLLED TO PERMIT COMPLETE INFILTRATION OF CARBON PREFORMS, AND THUS OFFERS AN ATTRACTIVE ALTERNATIVE TO METAL HALIDE CVI. IN PHASE I WE WILL STUDY THE DECOMPOSITION OF ORGANOMETALLIC HAFNIUM CARBIDE SOURCE REAGENTS, QUANTIFY AND MODEL THE INFILTRATION CAPABILITIES OF THE OMCVD PROCESS, AND INFILTRATE A CARBON PREFORM. THE INFILTRATION CARBON PREFORM WILL BE DELIVERED FOR EVALUATION. IN PHASE II, WE WILL EXTEND THE METHOD TO INCLUDE MIXED CARBIDE/NITRIDE/BORIDE SYSTEMS WHICH ARE PREDICTED TO OFFER THE ULTIMATE IN OXIDATION PROTECTION.