Solid Solution and Isotope Effects on the Properties of Boride Ceramics

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NON-TECHNICAL DESCRIPTION: The proposed research will focus on the fundamental thermal properties and oxidation response of boride ceramics such as zirconium diboride (ZrB2). Boride ceramics are capable of withstanding extreme thermal, mechanical, and chemical environments such as those associated with hypersonic flight, advanced ceramic-based cutting tools, buffer layers for microelectronic circuits, and inert matrix fuel forms for nuclear reactors. A deeper understanding of the thermal properties and oxidation response is needed to enable designers of future systems to fully utilize the unique combination of properties offered by refractory diborides and other ultra-high temperature ceramics (UHTC). The ability to use these materials in commercial products would allow systems to operate more reliably and at higher temperatures, which will increase efficiency and decrease energy consumption.TECHNICAL DETAILS: The goal of the proposed effort is to understand the elevated temperature thermal properties and environmental response of refractory diboride ceramics. Zirconium diboride will serve as a representative system, but the research will also encompass other diborides. The research is motivated by contradictory and unexplained thermal property and oxidation results, which may be due to variations in the amounts and compositions of impurities introduced during synthesis and processing. A combination of experimental studies, physics-based modeling, and analytical characterization will be used to investigate the roles of trace impurities, intentional solid solution additions, and the isotopes of the constituent elements on thermal properties and oxidation behavior. The research has the potential to transform the understanding of boride ceramics, which could enable their utilization in future generations of hypersonic aircraft, cutting tools, electronic devices, or nuclear reactors. The project will train two graduate students and at least one undergraduate per year in specialized techniques required for processing, testing, and characterizing materials for extreme environments. The project team will also promote potential careers in science and engineering to K-12 students, primarily through a statewide math and science competition for high school students.