TITANIUMAND HAFNIUM-COATED TUNGSTEN POWDERS FOR KINETIC ENERGY PENETRATORS

DEPLETED URANIUM (DU) IS THE STATE-OF-THE-ART MATERIAL FOR KINETIC ENERGY PENETRATORS USED TO DEFEAT STEEL AND COMPOSITE ARMORS. DU ALLOYS, HOWEVER, ARE COSTLY TO FABRICATE, HANDLE, AND STORE BECAUSE OF AN EXTREMELY COMPLEX METALLURGY AND THE OBVIOUS HEALTH FACTOR ASSOCIATED WITH THE USE OF URANIUM. TUNGSTEN COMPOSITE MATERIALS ARE ALSO USED IN KINETIC ENERGY PENETRATORS, OFFERING EASIER AND SAFER FABRICATION, HANDLING, AND STORAGE BUT TO DATE LACKING THE PERFORMANCE OF DU. THE MECHANISMS BY WHICH A PENETRATOR DEFEATS AN ARMOR ARE DIFFICULT TO DETERMINE, BOTH EXPERIMENTALLY AND FROM FIRST PRINCIPLES. RECENT EXPERIMENTS HAVE IDENTIFIED THE PRESENCE OF AN "ADIABATIC SHEAR" MECHANISM THAT APPEARS TO BE IMPORTANT IN THE PENETRATION OF ROLLED HOMOGENEOUS ARMOR BY DU PENETRATORS. IN THIS PHASE I PROGRAM, ULTRAMET PROPOSES TO APPLY TITANIUM AND HAFNIUM COATINGS TO TUNGSTEN PARTICLES BY CHEMICAL VAPOR DEPOSITION (CVD) USING AN ESTABLISHED FLUIDIZED-BED POWDER COATING TECHNIQUE. BOTH TITANIUM AND HAFNIUM ARE KNOWN TO EXHIBIT THE ADIABATIC SHEAR PHENOMENON. HIGH STRAIN RATE EXPERIMENTS (\10(4)/SEC) WILL BE PERFORMED TO ESTABLISH THE PRESENCE OR ABSENCE OF THIS MODE OF DEFORMATION IN SMALL CYLINDRICAL SPECIMENS OF TI/W AND HF/W COMPOSITES.