Join us as The University of Virginia’s Elizabeth Opila presents her talk on November 6th at 3pm in Maryland Hall room 110.
Abstract: Thermochemical response of refractory materials in ultra-high temperature dissociated oxygen
Hypersonic flight requires vehicles with sharp leading edges to enable maneuverability. Flight at velocities greater than Mach 5 results in shock waves in close proximity to the vehicle leading edge and a large amount of aerodynamic heating. In addition, dissociation of oxygen in the shock wave increases the complexity of the environment. Typical testing of materials for hypersonic leading edges is conducted in arc jet facilities which are not capable of separate effect studies of temperature and oxygen dissociation. Furthermore, this testing is extremely expensive. In this presentation, an economical benchtop facility designed for separate effect studies of materials response to ultra-high temperatures and oxygen dissociation will be described. The system is constructed for resistive heating of conductive materials to 2400°C in either molecular oxygen or partially dissociated oxygen. Oxygen dissociation is accomplished through creation of a non-equilibrium micro-plasma. Results for the oxidation of tantalum will be presented showing significant increases of the oxidation rate in dissociated oxygen relative to those observed in molecular oxygen at temperatures up to 1500°C. At temperatures above 1500°C the thermally grown tantalum oxide becomes dense and protective; oxidation rates in dissociated and molecular oxygen become indistinguishable. Preliminary studies on other Group IV, V, and VI metals and carbides are underway. The goal of this work is to develop predictive models for oxidation of refractory materials in hypersonic flight.
Bio: Elizabeth Opila
Elizabeth Opila is Chair and Professor of Materials Science and Engineering, the Rolls-Royce Commonwealth Professor of Engineering at the University of Virginia with a courtesy appointment in the Department of Mechanical and Aerospace Engineering. She is also the Director of the Rolls-Royce University Technology Center for Advanced Materials Systems at the University of Virginia. Prior to 2010, she held the position of Materials Research Engineer at the NASA Glenn Research Center in Cleveland, OH for 19 years where she worked primarily on ceramics for applications in turbine engines, rocket engines, hot structures for thermal protections systems, and other power and propulsion applications. Her current research focus includes understanding thermodynamic and kinetic mechanisms for material degradation in extreme environments, development of life prediction methodology based on understanding of fundamental high temperature chemical reaction mechanisms, and materials development for protection of materials from extreme environments. She studies thermochemical stability of ceramic matrix composites, refractory metals and alloys, ultra-high temperature ceramics, and environmental and thermal barrier coatings using a variety of specialized experimental approaches, materials characterization, and computational methods. Prof. Opila received her BS in Ceramic Engineering from the University of Illinois, her MS in Materials Science from the University of California Berkeley, and her PhD in Materials Science from the Massachusetts Institute of Technology. She is Fellow of the American Ceramic Society and the Electrochemical Society and recipient of the 2021 American Ceramic Society’s Arthur L. Friedberg Award. She has approximately 150 publications, is editor of 10 proceedings volumes, and coinventor on six patents.