THE FEASIBILITY OF USING ULTRASONICS TO ENHANCE LIQUID METAL INFILTRATION OF REINFORCING YARNS AND FIBERS

SEVERAL NEW CLASSES OF LOW DENSITY, HIGH STRENGTH, HIGH MODULUS YARNS AND FIBERS SUITABLE FOR REINFORCING METAL MATRIX COMPOSITES HAVE EMERGED WITHIN THE LAST DECADE; AMONGST THESE ARE THE GRAPHITE YARNS, THE SILICON CARBIDE FIBERS AND YARNS. UNFORTUNATELY, THESE YARNS ARE NOT READILY WETTED BY METALS AT STANDARD MELT TEMPERATURES, BUT REQUIRE EITHER COATINGS OR SUPERHEATED MELTS TO ACCOMPLISH WETTING. MCI HAS DEVELOPED THE TIB COATING PROCESS WHICH HAS BEEN SUCCESSFUL FOR CONVERTING THESE FIBERS INTO PRECURSOR METAL MATRIX COMPOSITES. OCCASIONALLY THE COATING DOES NOT COMPLETELY PENETRATE THE YARN TOW CAUSING A VOID OR UNINFILTRATED ZONE. THE USE OF ULTRASONICALLY ENHANCED INFILTRATION MAY: ELIMINATE DEFECTS, VOIDS IN INFILTRATED AREAS, PERMIT DIRECT INFILTRATION WITHOUT ACTIVATION COATING(S), REDUCE NECESSITY FOR SUPERHEATED MELTS TO INFILTRATE YARNS AND FIBERS.THIS CONCEPT, IF FEASIBLE, MAYBE TRANSITIONED TO THE INFILTRATION OF WOVEN TAPES AND FIBER PREFORMS. THE OBJECTIVE OFTHIS PROPOSED PHASE I EFFORT IS TO ESTABLISH THE FEASIBILITY FOR ENHANCING THE KINETICS OF INFILTRATING YARNS AND FIBERS TO INCREASE THE QUALITY OF COMPOSITES AND LOWER COSTS.