Thermodynamics of Materials in Extreme Environments: Thermodynamics, Stability, and Reactivity of Materials under Extreme Conditions
Sponsored by: ACerS Basic Science Division, ACerS Energy Materials and Systems
Program Organizers: Xiaofeng Guo, Washington State University; Kristina Lilova, Arizona State University; Kyle Brinkman, Clemson University; Alexandra Navrotsky, Arizona State University; Jake Amoroso, Savannah River National Laboratory; Xingbo Liu, West Virginia University; Gustavo Costa, NASA Glenn Research Center
Wednesday 8:00 AM
November 4, 2020
Room: Virtual Meeting Room 29
Location: MS&T Virtual
Session Chair: Xiaofeng Guo, Washington State University
8:00 AM Cancelled
Thermodynamics of An-Cl Complexes at High Temperature and Pressure: Ping Yang1; Xiaobin Zhang1; Morgan Kelley1; Enrique Batista1; Jason Baker1; Hakim Boukhalfa1; Artaches Migdissov1; Hongwu Xu1; 1Los Alamos National Laboratory
Nuclear energy represents a critical means to ensure sustainable energy supplies and curb greenhouse gas emissions. However, the development of nuclear energy systems is still hampered by safety concerns associated with the handling, processing, and disposing of spent fuel and high-level waste. One leading candidate approach is the storage of spent fuel in geological repositories. The behavior of actinides in high P-T environments is a fundamental knowledge gap with little understanding of complexation and thermodynamics of 5f-elements at geothermal relevant P-T conditions of these proposed disposing facilities. In this talk, we will present the impact on the chemical species and their thermodynamics from the elevated temperature and pressure based on the first-principle methods. The predicted results were validated by experimental Raman and XAS measurements in a hydrothermal diamond-anvil cell. The close integration between theory and experiment is the key to push forward the understanding of f-element chemistry at hydrothermal conditions.
8:30 AM Invited
Improved CMAS Resistance of Environmental Barrier Coatings via Tailoring Phase and Composition of Mixed Rare Earth Silicates: Elizabeth Opila1; Rebekah Webster1; Cameron Miller1; Clark Luckhardt1; 1University of Virginia
Environmental barrier coatings (EBCs) are required to protect SiC-based composites from rapid water vapor degradation in turbine engine combustion environments. State-of-the-art EBC materials are rare earth silicates, chosen for their reduced silica activity, chemical compatibility and thermal expansion match with the substrate. However, deleterious reactions with CMAS (CaO-MgO-Al2O3-SiO2) that is ingested into aircraft turbine engines remain a challenge. CMAS melts at approximately 1200C and can infiltrate/react with the coating, degrading the coating microstructure via crack, blister and pore formation. One approach to mitigate the degradation is to formulate coating compositions that promote CMAS reactions to form dense product phases, such as apatite, that limit further infiltration and reaction. In this presentation, novel EBC materials are described that show promise for mitigating EBC–CMAS reactions. These compositions include mixed rare earth mono- and disilicates, mixed rare earth disilicate-rare earth oxides, and mixed rare earth cations in a single monosilicate solution phase.
9:00 AM
Exploring Extreme Environments via In-situ Electron Microscopy: Khalid Hattar1; 1Sandia National Laboratories
Understanding the thermodynamic stability of materials with small second phases and other heterogenous structures often requires the resolution provided by advanced electron microscopy techniques. In addition, many of the coupled extreme environments seen in nuclear, space, geological, and other harsh environments, create a great number of possible conditions in which new phases and microstructures might be present. In this presentation, we will highlight how advanced electron microscopy techniques can be utilized to characterize everything from solid state noble gasses trapped in ordered arrays of nanoscale bubbles through amorphous intergranular films created or modified through extreme thermal and radiation conditions. This presentation will highlight combined in-situ experiments with controlled radiation damage and ion implantations, while at temperatures ranging from 77K to nearly 2,000K and under quantified mechanical loading provided by the in-situ ion irradiation transmission and scanning electron microscope. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.