Manufacturing and Processing of Advanced Ceramic Materials: Novel Processing of Oxide Ceramics II
Program Organizers: Bai Cui, University of Nebraska Lincoln; James Hemrick, Oak Ridge National Laboratory; Mike Alexander, Allied Mineral Products; Eric Faierson, Iowa State University; Keith DeCarlo, Blasch Precision Ceramics
Wednesday 2:00 PM
October 12, 2022
Room: 411
Location: David L. Lawrence Convention Center
Session Chair: Yan Chen, Oak Ridge National Lab; Chao Ma, Texas A&M
2:00 PM Invited
Neutron Scattering Visualizing Defects Generation and Structure Recovery in Ball-milled Spinel Oxide: Yan Chen1; Ke An1; 1Oak Ridge National Laboratory
In complex oxides, the crystal defects such as atom disordering, vacancies and incoherent boundaries usually act as determinative factors of materials’ superior performance. The understanding and control of those defects in hierarchical structures are essential in the design of material synthesis and manufacturing. Neutron diffraction has unique capabilities to detect vacancies of light-weight elements and ordered arrangement of transition-metal-elements in lattice; the small-angle neutron scattering reveals the evolution of crystallites from nano to micro scale; the in-situ approach enables revealing the intermediate status and reversible process in synthesis. This presentation demonstrates those capabilities via an example of high-energy ball milling on LiNi0.5Mn1.5O4 spinel for energy storage use. The ball-milling effects on structure breakdown, defect generation and atom disordering are revealed. The structure recovery is visualized in the subsequent annealing. This study illustrates that neutron characterization is valuable to guide optimization of synthesis for advanced materials.
2:30 PM
Characterization of Early Stage Sintering in Hydroxyapatite via Thermal Conductivity Measurements: Anne Leriche1; Benoit Nait-Ali2; David Smith2; 1UPHF - LMCPA; 2IRCER
In the last ten years, ceramic densification techniques have been developed, such as spark plasma sintering or microwave assisted heating, to limit grain growth and promote porosity elimination at lower temperatures. If the benefit of using these techniques on the final microstructure has been well established, their impact on the early stages of sintering has not yet been elucidated. The aim of the present work is to follow neck formation and densification in hydroxyapatite ceramics via thermal conductivity evaluation. An analytical model is proposed to describe the thermal conductivity of the green body / partially sintered ceramic in terms of interparticle contact area, porosity, grain size and the intrinsic grain conductivity. Samples were made using conventional sintering, microwave sintering and spark plasma sintering and characterized by laser flash measurements. Finally, the thermal conductivity evolution of a hydroxyapatite green body during the firing cycle is proposed.
2:50 PM
Investigation of Electrical Properties of BaTiO3-PEEK cComposite Processed by Cold Sintering: Toshiki Okazaki1; Clive Randall2; 1KYOCERA Corporation; 2The Pennsylvania State University
Cold Sintering caused a significant change in the sintering temperature of the ceramics. Ceramic sintering at a low temperature of 300 °C or less has enabled a wide range of ceramic composite materials to be selected. In this study, PEEK was added to barium titanate, which is widely used as a dielectric material, and cold sintering was performed. Pellets made of barium titanate alone are brittle, and the flux (barium hydroxide octahydrate) used in cold sintering process easily absorbs moisture and tends to fluctuate in characteristics. The addition of PEEK is expected to provide advantages such as improved mechanical strength, moisture resistance, and improved breakdown field strength. These property improvements help improve reliability in the design of ceramic capacitors. We will introduce various characteristics and the formed microstructure.
3:10 PM
Thermal and Mechanical Properties of Freeze-tape Cast Derived Ceramic-metal Composites: Amanda Marotta1; Stephen Sofie1; 1Montana State University
Freeze-Tape Cast processing as a platform for fabricating cermets yields non-traditional microstructures that can contribute to novel and tailorable anisotropic properties. Uniquely, structures with low phase tortuosity through-plane, and ceramic loading from <10 – 40 volume percent, can allow full percolation of metallic phase constituents. This combination is particularly attractive in mechanically robust, thermal management substrates. This work explores the fabrication and properties of yttria-stabilized zirconia (YSZ) and copper cermets, achieved through a molten copper oxide synthesis route. In and through plane anisotropy, driven by pore orientation, is quantified, where variation in CTE spans ~ 80%, and electrical conductivity up to ~ 66%, depending on ceramic volume fraction. Biaxial flexure testing indicates substantial plastic deformation contributed from the percolated metallic phase. Micro-indentation was utilized to examine the fracture mechanisms. Scanning electron microscopy and elemental characterization were used to study the ceramic-metal interface towards establishing the mechanistic drivers of microstructure-performance relation.
3:30 PM Break
3:50 PM Invited
Ultrafast High Temperature Sintering of Ceramic Materials for High Temperature Applications: Hua Xie1; Ji-Cheng Zhao1; David Clarke2; Jian Luo3; Liangbing Hu1; 1University of Maryland, College Park; 2Harvard University; 3University of California San Diego
Ceramic materials such as oxides, borides, silicates, and carbides are prominently employed for various applications in high-temperature environments. However, the fast development of new ceramic compositions (e.g. high entropy ceramics) is severely limited by the time-consuming sintering process. Herein, we present an ultrafast high-temperature sintering (UHS) technique for the fabrication of ceramic materials via radiative heating under an inert atmosphere. We employ a carbon-based heater to generate the Joule heat for the fast-sintering method. The ceramic is rapidly heated up to the temperature range of 1,500 - 3,000 K and the heating duration persists from several seconds to minutes depending on the ceramic materials. We have demonstrated how to tune the sintering parameters for different ceramic materials with bulk or coating forms and give examples of high entropy boride composites and ceramics for next-gen thermal barrier coating applications. This strategy can be also applicable to other ultra-high temperature ceramics.
4:20 PM
A Polyvinyl Pyrrolidone Based Binder for PZT Ceramics: Eric Neuman1; Emma MacLaughlin1; Catherine Colletti1; Jada Beltran1; 1Sandia National Laboratories
The behavior of a polyvinyl pyrrolidone based binder system was evaluated for dry pressing of lead-zirconate-titanate bulk ceramics. Three polyvinyl pyrollidones, Kollidon 25, Kollidon 90F, and Kollidon VA64, were blended with up to 50 wt% polyethylene glycol and 20 wt% glycerin. The glass transition temperature, thermal decomposition behavior, and compaction behavior and green mechanical properties when mixed with PZT were evaluated. A binder system with orders-of-magnitude improvement in compaction behavior and green mechanical properties was developed. Optimization of the binder system using statistical design of experiments will be discussed.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA000352
4:40 PM
Preparation of BaTiO3 Composites by Cold Sintering Process: Takashi Nunokawa1; Clive Randall1; 1The Pennsylvania State University
Cold sintering process (CSP) has attracted much attention because of sintering various ceramics in the low temperature. In particular, barium titanate (BaTiO3) has been used for multi-layer ceramic capacitors. In the conventional sintering, BaTiO3 is sintered at temperature more than 1000 ˚C. Therefore, we investigated about preparation process of BaTiO3 sintered body by CSP. As a procedure, after mixing homogenously BaTiO3 powder with flux, we densify the powder below 300 ˚C, under uniaxial pressure of 350 MPa with a transient phase. As a result, we obtained the sintered body of the relative density more than 90 %. In this study we will consider the microstructural -processing- property relations for the cold sintered BaTiO3, we are particularly interested in the crystal structure of the ferroelectric phase, and electrical properties as a function of temperature and applied field within pure BaTiO3 and in composite forms with mixing polymer in the grain boundaries.
5:00 PM
Passive pH Control Using Ceramic Particles: Alicia Mayville1; William Carty1; 1New York State College of Ceramics at Alfred University
Several variables contribute to the pH of an aqueous solution, including the presence of acid or base, dissolved gasses, temperature, and impurities. When ceramic particles are added to an aqueous suspension, the pH will drift to the point of zero charge(pzc), or the isoelectric point(iep) in the presence of an indifferent electrolyte. The magnitude of this change is driven by the concentration of ceramic particles, and the rate of hydration reactions at the particle surface. In this study several variables were evaluated on the change in pH with time, including the surface area ratio to bulk fluid volume (area/liter), initial suspension pH, and the concentration of impurity ions, by measuring the pH using calibrated pH probes. The results demonstrate that if the suspension pH was shifted, the pH would return to the pzc over time, depending on the extent of the pH shift and the available reactive surface area.