FAST-PULSE HOT PRESSING WITH FINE-SCALE ADIABATIC HEATING

THE PLANNED PROCESS DEVELOPMENT RELATES TO FASTPULSE HOT PRESSING USING INPUT POWER DENSITIES ON THE ORDER OF A GIGAWATT/CC. POWER INPUTS OF THIS MAGNITUDE CAN PRODUCE ADIABATIC HEATING ON A FINE SCALE IN MIXTURES OF DIELECTRIC AND CONDUCTIVE POWDERS. MELTING OF THE CONDUCTIVE PHASE WITH MINIMAL HEAT LOSS TO THE DIELECTRIC PHASE DURING HEATING ALLOWS FOR CONSOLIDATION UNDER PRESSURE IN A VERY SHORT TIME, WITH MINIMUM ENERGY INPUT. FOR COMPOSITES WITH A LARGE FRACTION OF DIELECTRIC PHASE, THE EQUILIBRIUM TEMPERATURE IS CONSIDERABLY LOWER THAN THE MELTING POINT OF THE CONDUCTIVE PHASE, ENABLING THE USE OF HIGH PRESSURES AND LOW-COST MATERIALS TO CONSTRUCT THE EQUIPMENT. PHASE I IS INVESTIGATING GRAPHITE/DIAMOND AND BORON CARBIDE/TITANIUM NITRIDE AS POSSIBLE MATERIALS SYSTEM. A POLYCRYSTALLINE DIAMOND COMPACT CAN PROBABLY BE PRODUCED THROUGH RAPID HEATING AND COOLING AT PRESSURES BELOW THE EQUILIBRIUM PRESSURE FOR DIAMOND. THE BORON CARBIDE/TITANIUM NITRIDE SYSTEM OFFERS THE POTENTIAL FOR METASTABLE SOLID SOLUTIONS THAT CAN BE HEAT TREATED TO PRODUCE VERY FINE MICROSTRUCTURE WITH ENHANCED FRACTURE TOUGHNESS. IN PHASE I, THE MATERIALS ARE FULLY CONSOLIDATED AND STUDIED BY X-RAY DIFFRACTION, THE PHASES ARE IDENTIFIED, AND KEY MECHANICAL PROPERTIES ARE MEASURED.