Powder Materials for Energy Applications: Ceramic Powder Materials
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Powder Materials Committee
Program Organizers: Kathy Lu, University of Alabama Birmingham; Eugene Olevsky, San Diego State University; Hang Yu, Virginia Polytechnic Institute And State University; Ruigang Wang, Michigan State University; Isabella Van Rooyen, Pacific Northwest National Laboratory
Monday 2:00 PM
March 15, 2021
Room: RM 24
Location: TMS2021 Virtual
Session Chair: Eugene Olevsky, San Diego State University; Isabella Van Rooyen, Pacific Northwest National Laboratory
2:00 PM
Electric Current Effects in Spark Plasma Sintering: Heating Pathway Analysis: Eugene Olevsky1; Geuntak Lee1; Charles Maniere1; Elisa Torresani1; 1San Diego State University
High rate field-assisted processing involves transient thermal and non-thermal phenomena, which, if properly managed, provide unique environment for densification and microstructure retention. Thereby, an efficient field-assisted sintering process utilizes conditions of controlled non-equilibrium. For practical realization of this concept the in-depth analysis of the role of electrical current pathways in mass transport during field-assisted sintering is necessary. The impact of the electric current on sintering is revealed by introducing the three heating modes during spark plasma sintering enabling the different electric current density under the same temperature. The experimental evidence of the electric current effect on sintering is demonstrated by the determination of the electric current related constitutive parameters obtained from the three heating modes. The enhancement of the dislocation motion and the reduction of the flow stress under the electric current passage are experimentally proven by the mechanical strength tests and using the X-ray diffraction results.
2:20 PM
Electrochemical Deposition Synthesis of CeO2 Nanoarrays: Ruigang Wang1; Yifan Wang1; 1The University of Alabama
In recent years, hydrothermal method has been widely applied on the synthesis of ceria (CeO2) for controlling its nanoshapes (rods, spheres, cubes, tubes, and octahedra). However, there are many challenges to prepare well-dispersed high surface area CeO2 via hydrothermal route, including the particle agglomeration and difficulty to scale up for device development. In this study, we report a facile electrochemical deposition method to fabricate CeO2 nanoarrays on Ti substrate under variable electrochemical conditions. In our preliminary results, a large number of well-aligned CeO2 nanoarrays with controlled density and length-to-diameter ratio were successfully fabricated on Ti foil electrode using a mixture of Ce(NO3)3, KCl and NH4Cl solution as electrolyte, which have showed great potential as catalyst supports for several pollutant gas conversion reactions.
2:40 PM Invited
High Temperature Corrosion and Irradiation Behavior of Silicon Carbide and Nanostructured Ferritic Alloy Composites: Kaustubh Bawane1; Kathy Lu2; Xian-Ming Bai2; Kaijie Ning2; Wei-Ying Chen3; Meimei Li3; 1Idaho National Laboratory; 2Virginia Tech; 3Argonne National Laboratory
Silicon carbide and nanostructured ferritic alloy (SiC-NFA) composites have the potential to maintain the outstanding high temperature corrosion and irradiation resistance required for nuclear claddings. In this work, high temperature corrosion studies on SiC-NFA composites were performed at various temperatures in air+water vapor environment. The improved oxidation resistance for higher SiC content composites is attributed to improved kinetics for the formation of dense Cr2O3 and SiO2 protective layers. In-situ transmission electron microscopy (TEM) was used to study microstructural evolution of NFA and SiC-NFA composite under 1 MeV Kr ion irradiation at 300oC and 450oC. NFA and SiC-NFA showed similar loop density and size during irradiation at 300oC. However, at 450oC, SiC-NFA composites showed significantly lower loop density and size. At 300oC, ½<111> type loops were observed in both NFA and SiC-NFA. Interestingly, at 450oC, <100> type loops were dominant in NFA while ½<111> loops were dominant in the SiC-NFA sample.
3:10 PM
Oxidation Behaviors of Matrix-grade Graphite in Water Vapor Ingress Accidents for High Temperature Gas-cooled Reactors: Kathy Lu1; Yi Je Cho1; 1Virginia Polytechnic Institute and State University
Graphite is one of the most important structural materials for TRISO fuels. Different from nuclear-grade graphite, matrix-grade graphite has a small amount of incompletely graphitized binder, which makes it vulnerable to oxidation. Only few studies dealt with the oxidation behaviors of matrix-grade graphite in air ingress accident scenarios, even though water vapor ingress is more probable than air ingress for high temperature gas-cooled reactors (HTGR). Thus, oxidation properties, microstructure changes, and mechanical properties should be studied in order to predict and analyze matrix graphite performance under HTGR accidental conditions. In this study, the oxidation behaviors of ARB-B1-Z007 matrix-grade graphite were investigated. The postulated water vapor ingress conditions were 800–1200 °C in He/10–40 vol% water vapor mixed atmospheres. Mass change, evolving gas, composition, microstructure, and mechanical properties were analyzed. The resultant understanding can be applied to the development of new graphitic materials and design of new HTGR fuel systems.
3:30 PM
Simulation of C-SiOC Coatings on Yttria Stabilized Zirconia Microspheres in a Fluidized Bed Coater Based on Multiphase Flow with Interface Exchange: Kathy Lu1; Sanjay Kumar1; 1Virginia Polytechnic Institute and State University
C-SiOC coating process on yttria stabilized zirconia (YSZ) microspheres (500 µm) was simulated. The spouted fluidized bed coater configuration was modelled for simulation to understand the fluid and particle dynamics using a Multiphase Flow with Interface Exchange (MFIX) software. Two different coater configurations were studied. Additionally, the influence of Wurster tube configuration at different height intervals from the bottom of the coater set-up was investigated. The effects of process variables such as fluid viscosity, fluid mass in-flow pressure, and geometrical configuration on the particle residence time distribution were also quantified. Instantaneous particle position, particle residence time, and particle velocity distribution inside a fluidized bed coater were evaluated. The effects of geometry and the influence of Ar flow condition at 800C at different mass in-flow pressure were also investigated. The derived results were utilized for coating experiments using a Glatt coater to yield homogeneous and defect-free coatings.