ACerS Robert B. Sosman Award Symposium: Advancing the Science of Materials for Extreme Environments: Session II
Sponsored by: ACerS Basic Science Division
Program Organizers: Yiquan Wu, Alfred University; Greg Hilmas, Missouri University of Science and Technology; Eric Wuchina, NSWCCD
Wednesday 2:00 PM
October 12, 2022
Room: 407
Location: David L. Lawrence Convention Center
Session Chair: Greg Hilmas, Missouri University of Science and Technology; Eric Wuchina, NSWCCD
2:00 PM Invited
Progress in Manufacturing Ultra-High Temperature Ceramic Matrix Composites (UHTCMCS): Jon Binner1; 1University of Birmingham
There is an increasing demand for advanced materials, for aerospace and other applications, with temperature capability ranging from 1500oC to well over 2000°C and able to survive highly corrosive environments whilst subject to intense heat fluxes and mechanical stresses. The interaction of environmental conditions together with the requirement that dimensional stability is maintained makes the selection of suitable materials extremely challenging. This paper discusses the design, development, manufacture and testing of ultra-high temperature ceramic matrix composites based on C fibre preforms enriched with ultra-high temperature ceramic (UHTC) powders and with a carbon matrix infiltrated by RF-heated chemical vapour infiltration (CVI).
2:30 PM Invited
Thermodynamic Assessment of Zr-B-C-O System Applied to Ultra High Temperature Ceramic Processing & Oxidation
: Erica Corral1; 1University of Arizona
A thermodynamic model for the Zr-B-C-O quaternary system was developed to advance the fundamental understanding of ultra-high temperature ceramic processing science and predictability in extreme environments. We conducted this assessment using the CALPHAD framework and data obtained from first-principles calculations and literature. The calculated phase diagrams of the Zr-B-C-O system show the processing conditions for the prediction of accurate experimental parameters such as temperature, and gaseous environment, as well as additive content that maximizes oxygen removal and minimize formation of undesirable compounds. Improvements to the thermodynamic database include parameterization and incorporating first principle calculations for binary and ternary components of the Zr-B-C-O system. Examples of applying the calculated phase equilibrium diagrams to densify high purity and high strength ZrB2 ceramics using spark plasma sintering will be discussed. The model also predicts the stability fields of ZrB2 as a function of temperature and partial pressure for atomic and molecular oxygen.
3:00 PM Invited
Exploring Microstructural Complexity in UHTCs for New Heat Management Strategies Using Cost-Effective Manufacturing Approaches: Carolina Tallon1; 1Virginia Polytechnic Institute
Thermal protective systems for hypersonic vehicles needs to survive large heat fluxes, extreme temperatures, extensive thermal gradients, stagnation pressures and oxidative environments. They also need to show minimal material ablation and overall weight, with complex shapes. Although outstanding development has been achieved over the past 20 years for UHTCs, the state-of-art manufacturing and design still revolves around solid microstructures as heat sinks for leading edges. Recent advances in manufacturing paved the way for exploring different UHTC microstructures that could lead to other heat management strategies. In this talk, innovative colloidal processing approaches will be discussed to introduce controlled porosity, textured microstructures and high aspect ratio building blocks for UHTCs, to tailor thermomechanical response in different directions within the same component, and enable innovative active and passive cooling strategies. The manufacturing approaches discussed present a cost-effective emphasis to achieve that complexity with minimum additives, forces, low temperatures and number of steps
3:30 PM Break
3:50 PM Invited
High-entropy Transition Metal Diborides: Local Structure vs. Long-range Chemical Homogenity: Frederic Monteverde1; Mattia Gaboardi2; 1ISTEC-CNR; 2Elettra-Sincrotrone Trieste S.C.p.A.
High entropy materials represent a non-canonical type of crystalline structures which are formed when five or even more dissimilar elements find themselves constrained into degenerate sublattice sites. When this principle is applied to diborides, only one sublattice of the crystal (s.g. P6/mmm) is chemically disordered, while the remaining covalent B backbone is not. We present a broad investigation conducted on several high-entropy transition metal diborides using state-of-the-art synchrotron scattering and SEM-EDS techniques. The investigation has awarded us with deep insight into hitherto-unknown local distortions occurring around metals. Common features were observed between the average structure and the first-neighbors distances, regardless the number and type of substituted metals. The analysis of the first three scattering shells provides us with a handle on the underlying microscopic strains, which might be responsible for the improved thermophysical behaviour in this class of compounds.
4:20 PM Invited
High-entropy Rare-earth Zirconates for Thermal Barrier Coatings with Low Thermal Conductivity and Graceful Behavior during CMAS Corrosion: Guo-Jun Zhang1; 1Donghua University
Thermal barrier coatings (TBCs) with low thermal conductivity and good corrosion resistance to calcium-magnesium-alumino-silicates (CMAS) are important materials for the protection of the metallic parts or ceramic matrix composites from overheating during long-term use at high temperatures. Yttria-stabilized zirconia (YSZ) is the state-of-the-art TBC material and has been chosen as the industry standard. Great efforts have been devoted to explore new oxide compositions with lower thermal conductivity and better thermal stability for TBC applications in recent years. The A2B2O7-type rare-earth zirconates with pyrochlore structure are important candidates. Here, we report the preparation and characterization of high-entropy pyrochlores based on ternary rare-earth zirconates (RE2Zr2O7). Five lanthanides (La2O3, Nd2O3, Sm2O3, Eu2O3, and Gd2O3) and Y2O3 were selected as the starting materials. The thermal conductivity, thermal stability at elevated temperatures, thermal cycling test of the coatings prepared by atmospheric plasma spraying (APS), as well as corrosion resistance to CMAS were investigated and discussed.
4:50 PM Invited
From Academic Research on UHTCs to Industry R&D and Entrepreneurship: Sumin Zhu1; 1MSE Supplies LLC
Studies on Ultra-High Temperature Ceramics (UHTCs) require the fundamental understanding of the structure, processing, properties, and performance of these ceramic materials. This presentation will highlight the author’s experience during his Ph.D. research on UHTCs, and then discuss why such research experience is extremely useful in new product development in industry. Further, this presentation will discuss the author’s entrepreneurial experience and conclude by sharing some examples of bridging research, manufacturing, and characterization of UHTCs.