Low Cost C/C Divert Thrust Chambers Via Rapid, Forced Flow CVI

KENETIC ENERGY (KE) WEAPONS CURRENTLY IN DEVELOPMENT OR BEING CONSIDERED UNDER THE STRATEGIC DEFENSE INITIATIVE (SDI) INCLUDE A VARIETY OF GROUND- AND SPACE-BASED INTERCEPTORS. MANY OF THESE PROPOSED SYSTEMS ARE CRITICALLY DEPENDENT ON THE DEVELOPMENT OF ADVANCED LIGHT-WEIGHT, HIGH-TEMPERATURE MATERIALS FOR AXIAL AND/OR DIVERT PROPULSION SUB-SYSTEMS. RECENT HOVER TESTS OF THE LEAP KINETIC KILL VEHICLE HAS SUCCESSFULLY DEMONTRATED THE POTENTIAL OF LOW-DENSITY, OXIDATION-RESISTANT CARBON/CARBON (C/C) COMPOSITES FOR DIVERT THRUST CHAMBER (THRUSTER) APPLICATIONS. CURRENT STATE-OF-THE-ART GBI AND THAAD C/C COMPOSITE THRUSTERS ARE BEING FABRICATED USING 2-D TRIAXIALLY BRAIDED CARBON FIBER PREFORMS WHICH ARE SUBSEQUENTLY DENSIFIED WITH PYROLYTIC CARBON (PyC) BY METHODS OF CONVENTIONAL CHEMICAL VAPOR INFILTRATION (CVI). CONVENTIONAL, ISOTHERMAL/ISOBARIC CVI TECHNIQUES REQUIRE INTENTIONALLY SLOW DEPOSITION RATES IN ORDER TO UNIFORMLY INFILTRATE AND DENSIFY THE FIBROUS PREFORMS WHILE MINIMIZING THROUGH-THE-THICKNESS DENSITY GRADIENTS. THESE SLOW CVI DENSIFICATION PROCESSES ROUTINELY REQUIRE 300-600 HOURS TO COMPLETE, RESULTING IN VERY LONG PRODUCT LEAD TIMES AND THUS RELATIVELY HIGH PRODUCT COST. THE OBJECTIVE OF THIS PHASE I PROGRAM IS TO DEVELOP AND EVALUATE AN INNOVATIVE FORCED FLOW CVI PROCESS FOR THE RAPID DENSIFICATION OF C/C COMPOSITE DIVERT THRUSTERS. THE GOAL OF THIS DEVELOPMENT IS TO SUCCESSFULLY REDUCE THE DENSIFICATION CYCLE BY AT LEAST 75%, RESULTING IN A COMPOSITE THRUSTER FABRICATION COST REDUCE OF OVER 50%. TRIAXIALLY BRAIDED, MULTILAYER CARBON FIBER PROFORMS WILL BE FABRICATED OVER GEOMETRICALLY CONTOURED MANDRELS AND RAPIDLY DENSIFIED WITH PyC USING AN ECONOMICAL FORCED FLOW CVI TECHNIQUE. PROCESS CONDITIONS WILL BE ESTABLISHED FOR DENSIFYING THE THRUSTER COMPONENTD TO A TARGET DENSITY OF 1.75 GM/CM3 IN LESS THAN 100 HOURS. FOLLOWING DETAILED MACHINING, AN INTEGRATED/ADHERENT OXIDATION-PROTECTIVE SILICON CARBIDE (SiC) COATING WILL BE APPLIED TO THE INTERIOR SURFACE OF THE THRUSTER COMPONENTS BY CVI. TUBULAR COMPOSITE TEST SPECIMENS, REPRESENTATIVE OF BOTH THE COMBUSTION CHAMBER AND THE NOZZLE REGIONS, WILL BE PREPARED AND EXPERIMENTALLY EVALUATED TO DETERMINE THE HIGH-PRESSURE PERMEABILIT