Novel Reaction Processing Techniques for the Fabrication of Ultra-High Temperature Metal/Ceramic Composites with Tailorable Microstructures

Ultra-high temperature (i.e., > 2500°C) engineering applications present continued materials challenges. Refractory metal/ceramic composites have great potential to satisfy the demands of extreme environments (e.g., the environment experienced in solid rocket motors upon ignition), though general scalable processing techniques to fabricate complex shaped parts are lacking. The work embodied in this dissertation advances scientific knowledge in the development of processing techniques to form complex, near net-shape, near net-dimension, near fully-dense refractory metal/ceramic composites with controlled phase contents and microstructures.

Three research thrusts will be detailed in this presentation. First, the utilization of rapid prototyping techniques, such as computer numerical controlled machining and three dimensional printing, for the fabrication of porous tungsten carbide preforms and their application with the Displacive Compensation of Porosity process (a solid-volume-increasing reactive infiltration technique) to produce tungsten/zirconium carbide-bearing composites is demonstrated. Second, carbon substrates and preforms have been reactively converted to porous metal/metal carbide replicas via a novel gas-solid displacement reaction. Lastly, a reaction-based process for synthesizing refractory metal/ceramic micro/nanocomposites will be discussed. These novel reaction processing techniques combined have the potential to produce micro/nanostructured refractory metal/ceramic composite materials with tailorable microstructures for ultra-high temperature applications.