Manufacturing and Processing of Advanced Ceramic Materials: New Opportunities in Ceramic Processing II
Sponsored by: ACerS Manufacturing Division
Program Organizers: Bai Cui, University of Nebraska Lincoln; Mike Alexander, Allied Mineral Products, Inc.; Eric Faierson, Quad City Manufacturing Laboratory - Western Illinois University; James Hemrick, Oak Ridge National Laboratory; Keith DeCarlo, Blasch Precision Ceramics
Wednesday 8:00 AM
November 4, 2020
Room: Virtual Meeting Room 16
Location: MS&T Virtual
Session Chair: Yiquan Wu, Alfred University; Valerie Wiesner , NASA Langley Research Center
8:00 AM Invited
Developing Materials and Coating Technologies for Mitigation of Lunar Dust Adhesion and Abrasion: Valerie Wiesner1; Lopamudra Das2; Chris Wohl1; Glen King1; Keith Gordon1; Samuel Hocker1; Karen Taminger1; Sharon Miller3; 1NASA Langley Research Center; 2National Institute of Aerospace; 3NASA Glenn Research Center
In order to support long duration missions on the Moon’s surface, materials resistant to the harsh lunar environment are critically needed. Lunar dust poses a major threat to the durability of components and vehicles due to its fine, jagged morphology and highly abrasive nature, enabling the particles to adhere and embed onto surfaces of components and devices and potentially leading to premature failure. There is significant effort within NASA to develop novel materials and coating technologies to mitigate lunar dust adhesion and abrasion. This effort has been exploring a variety of production routes and examining properties of candidate material systems, including ceramic, metallic and polymeric. Manufacturing methods investigated include ceramic powder processing, additive manufacturing and surface modification via laser ablation patterning of bulk materials and coatings. An overview of ongoing NASA materials and coating research and development efforts to enable lunar surface exploration will be presented.
8:40 AM Invited
Neutrons Guide Materials Design and Synthesis of Functional Oxides: Yan Chen1; Ke An1; 1Oak Ridge National Laboratory
It is critical to precisely control atoms ordering, manipulate defect content and engineer morphology in material synthesis, in order to achieve advanced functionality in complex oxides. Understanding of synthesis mechanism accelerates smart material and process design beyond the less-efficient trial-and-error paradigm. Proven as a powerful tool, neutron diffraction is sensitive in detecting light elements (O, C, Li, etc.) and differentiating the neighboring transition-metal-elements. By utilizing sample environments that mimic material synthesis, in-situ neutron diffraction monitors the structure evolution in real time, and particularly, visualizes reversible transitions and intermediate phase involvement. Taking energy storage and conversion materials as examples, the synthesis mechanism and kinetics are revealed from the atomic structure change in material processing, such as solid-state synthesis, powder compacting and ball-milling, correlating to the functional performance. The picture neutron diffraction draws loops back to guide the synthesis and optimization for advanced materials.
9:20 AM Invited
Transparent Ceramics by Lithography-Based Additive Manufacturing: David Carloni1; Guangran Zhang; Yiquan Wu1; 1Alfred University
Transparent YAG ceramics have been fabricated by a lithography-based additive manufacturing method. Ceramic green bodies were printed using a photo-curable slurry which possessed sufficient flow properties to facilitate high-resolution and stable printing behavior. The printed and cured ceramics could be stable for a few months. After a slow de-binding process, the green body could be sintered to transparency by vacuum sintering only. Truly complex shaped objects are demonstrated to show the potential of lithography-based additive manufacturing in transparent ceramics processing.
10:00 AM Invited
Processing and Properties of High Thermal Conductive Silicon Nitride Ceramics: Kiyoshi Hirao1; You Zhou1; Hideki Hyuga1; Tatsuki Ohji1; 1National Institute of Advanced Industrial Science and Technology (AIST)
Silicon nitride has attracted much attention as advanced insulating substrates for next-generation high out-put power module because of its excellent mechanical properties with intrinsic high thermal conductivity. So far extensive research works have been carried out for increasing thermal conductivity without degrading the mechanical properties. Our group has succeeded in fabricating high thermal conductive silicon nitrides by nitriding Si powder compacts with sintering additives, followed by post sintering process. In this presentation processing strategy for improving thermal conductivity in silicon nitride is discussed in terms of decreasing impurity oxygen dissolved in beta-Si3N4 grains, so-called lattice oxygen, and mechanical (strength , fracture toughness and R-curve behavior), thermal (temperature dependence of thermal conductivity and coefficient of thermal expansion), and electrical (dielectric breakdown voltage) properties are introduced.
10:40 AM Invited
A Rational Design of Ultra-uniform Nanocrystalline Materials: Yanhao Dong1; Hongbing Yang2; Jiangong Li2; I-Wei Chen3; Ju Li1; 1Massachusetts Institute of Technology; 2Lanzhou University; 3University of Pennsylvania
Nanocrystalline materials often show superior properties and are thus of great interest. Much has been discussed about ultrafine grain sizes, but little is known about ultra-uniformity, defined as grain size distribution narrower than predicted by the classical theory of Hillert. Here we provide a generalized growth theory unifying the mean-field solutions from Lifshitz, Slyozov, Wagner (LSW) and Hillert. For curvature driven grain growth, we find for growth exponent n >1 a steady-state size distribution that is analytically solvable and the distribution narrows with increasing n. Experimental validation of this prediction is found in porous Al2O3 ceramics at various stages of sintering and in dense Al2O3 nanoceramics produced by two-step sintering with an extremely uniform microstructure of 34 nm average grain size. The mechanism of two-step sintering shall be discussed, which is supported by sharp grain boundary mobility transitions experimentally observed in yttria stabilized zirconia and pure tungsten.