IMPROVING THE UNIFORMITY OF CHEMICAL VAPOR INFILTRATION OF HFC AND HFB2 INTO FIBER PREFORMS

THIS PROJECT WILL EXAMINE THE UTILITY OF ALTERNATIVE METAL AND NONMETAL PRECURSOR SPECIES FOR CHEMICAL VAPOR INFILTRATION OF HFC AND HFB2 INTO CARBON FIBER AND BORON FILAMENT PREFORMS, RESPECTIVELY. IN PARTICULAR, THE USE OF PRECURSOR SPECIES WHICH REACT SLOWLY TO DEPOSITE THE MATRIX MATERIAL AT SLOWER RATES, THUS PROVIDING MORE UNIFORM DEPOSITION THROUGHOUT THE BULK OF THE FIBER PREFORM WHICH MAY AID IN ACHIEVING HIGHER MATRIX DENSITIES, WILL BE EMPHASIZED. A SYSTEMATIC SERIES OF EXPERIMENTS UTILIZING VARIOUS PERMUTATIONS OF METAL AND NONMETAL PRECURSOR SPECIES, DEPOSITION TEMPERATURES, TOTAL SYSTEM PRESSURES AND PRECURSOR GAS PARTIAL PRESSURES WILL BE PERFORMED. DEPOSIT UNIFORMITY (AT THE PREFORM SURFACE VERSUS INTERIOR REGIONS) AND STOICHIOMETRY AND OVERALL PROCES DEPOSITION RATES AND EFFICIENCIES WILL BE QUANTITATIVELY DETERMINED. THE PROPOSED APPROACH IS EXPECTED TO BE COMPLEMENTARY TO OTHER APPROACHES BEING STUDIED FOR ACHIEVING HIGHER MATRIX DENSITIES SUCH AS THE USE OF TEMPERATURE OR PRESSURE GRADIENTS DURING DEPOSITION. THE PROJECT WILL BE PERFORMED WITH THE ASSISTANCE OF RENSSELAER POLYTECHNIC INSTITUTE AS A SUBCONTRACTOR.