NOVEL MOLECULAR SOURCES FOR DISPERSING BORON IN CARBON-CARBON COMPOSITES

IMPROVING THE OXIDATION RESISTANCE OF CARBON-CARBON COMPOSITES IS KEY TO EXPANDING THE USE OF THIS MATERIAL SYSTEM INTO HIGHER TEMPERATURE APPLICATIONS. WHILE BORON PARTICLES HAVE BEEN ADDED TO THESE MATERIALS TO SEAL CRACKS IN PROTECTIVE COATINGS, OXIDATION OF THE CARBON MATRIX NEIGHBORING THE BORON PARTICLES SERIOUSLY AFFECTS COMPOSITE STRENGTH. THIS PROBLEM IS EXACERBATED BY A NATURAL SEGREGATION OF THE BORON PARTICLES TO FIBER RICH AREAS OF THE COMPOSITE. THE PHASE I PROGRAM PROPOSES THE USE OF NEW CARBORANE CHEMISTRY AS A MEANS OF ATOMICALLY DISPERSING BORON THROUGHOUT THE MATRIX. ROBUST CANDIDATE MOLECULES WILL BE IDENTIFIED, SYNTHESIZED, COMBINED WITH PHENOLIC RESINS FOR CONVERSION INTO CARBON TEST COUPONS FOR OXIDATION STUDIES. MICROANALYTICAL TECHNIQUES WILL BE USED TO MAP THE BOR ON DISTRIBUTION IN THESE SAMPLES FOR COMPARISON TO PARTICULATE DERIVED SAMPLES. THE PHASE II EFFORT WILL TRANSLATE THE RESULTS OF PHASE I INTO THE MANUFACTURE OF COMPOSITES FOR CYCLIC OXIDATION STUDIES.