Manufacturing and Processing of Advanced Ceramic Materials: New Opportunities in Ceramic Processing I
Sponsored by: ACerS Manufacturing Division
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
Monday 8:00 AM
October 18, 2021
Room: B234
Location: Greater Columbus Convention Center
Session Chair: William Fahrenholtz, Missouri University of Science and Technology; Waltraud Kriven, University of Illinois at Urbana-Champaign
8:00 AM Invited
Recent Progress in Fusion Welding of Structural Ceramics and Composites: William Fahrenholtz1; Greg Hilmas1; Jeremy Watts1; Jecee Jarman1; 1Missouri University of Science and Technology
This presentation will describe the fusion welding of boride and carbide based ceramics and ceramic matrix composites. Methods including plasma arc welding and gas tungsten arc welding have been developed in our laboratory for joining transition metal boride and carbide ultra-high temperature ceramics, which are amenable to fusion welding methods based on their intrinsic thermal and electrical conductivities. Welding is performed in a controlled atmosphere with low oxygen partial pressure to prevent oxidation of the welded parts. Welds are produced by preheating specimens to ~1500°C to mitigate thermal shock issues. Welding parameters including current, translation speed, and gas flow rates can be optimized using statistical methods to produce high quality welds. Weld microstructure development is affected by specimen composition and heating parameters and must be controlled to produce joints with acceptable mechanical behavior. Examples of welding of several ceramic compositions will be discussed.
8:40 AM
Surface Stengthening of Single-crystal Alumina by High-temperature Laser Shock Peening: Fei Wang1; Xueliang Yan1; Lei Liu1; Michael Nastasi2; Yongfeng Lu1; Bai Cui1; 1University of Nebraska Lincoln; 2Texas A&M University
This study reports a novel process of high-temperature laser shock peening (HTLSP) for surface strengthening of single-crystal ceramics such as sapphire and reveals its fundamental mechanisms. HTLSP at 1200 °C can induce a high compressive residual stress on the surface of sapphire while minimizing the damage of laser-driven shock waves. Transmission electron microscopy characterizations revealed high dislocation densities near the surface, suggesting that plastic deformation at an ultrahigh strain rate was generated by the high shock wave pressure. The HTLSP-induced compressive residual stress can significantly improve the hardness and fracture toughness of sapphire while maintaining its outstanding optical transmittance.
9:00 AM Invited
Low Energy Syntheses of Ceramic Powders and Composites: Waltraud Kriven1; 1University of Illinois at Urbana-Champaign
Any oxide ceramic of precise simple or complex composition can be made by the organic steric entrapment method (US Patent number 6,482,387 issued 2002). Cations in precise compositions are mixed in solution with 5 wt% organic polymer such as polyvinyl alcohol (for aqueous solutions) or ethylene glycol or polyethylene glycol oils (for alcoholic, non-aqueous solutions). Four times as many cation valence charges can be bound or mechanically entrapped as there are -OH or C-O-C- “functional groups” in the organic molecules. The resulting oxide powder consists of soft agglomerates of nanoparticles of the correct stoichiometry. The nanoparticle diffusion lengths enable UHT non-oxides such as carbides or nitrides to be fabricated under flowing argon or nitrogen, respectively. Geopolymers are self-assembled, amorphous, nanoparticulate, nanoporous inorganic oxide polymers made under ambient temperatures to form a rigid ceramic which is stable to 1000°C, whereupon it crystallizes. They can be 3D printed and readily scaled up.
9:40 AM
Textured UHTC Borides Using Extremely Low Magnetic Fields: Juan Diego Shiraishi Lombard1; Carolina Tallon2; 1Virginia Polytechnic Institute and State University; 2Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University
Textured Ultra-High Temperature Ceramics have shown potential for enhanced mechanical and thermal performance in extreme environments. In this work, analytical calculations and experiments are paired to demonstrate how extremely low magnetic fields in combination with high solid concentration suspensions with low viscosity lead to highly textured UHTC materials, using a very cost-effective manufacturing approach for this type of material.N52 grade NdFeB permanent magnets were utilized in a magnetically assisted slip casting process to create TiB2 with crystallographic texture. Analytical modeling of the forces involved in the process predicts formation of crystallographic texture under the estimated applied magnetic flux density of 0.55 - 0.6 T. The Lotgering orientation factors of sintered TiB2 processed with magnetic field parallel and perpendicular to the casting direction were 0.941 and 0.853, respectively, , with particle aligned domains that extends across several centimeters in the samples.
10:00 AM Break
10:20 AM Invited
Ultra-fast Laser Sintering of Alumina and the Microstructure Prediction Based on Machine Learning: Xiao Geng1; Jianan Tang1; Dongsheng Li2; Yunfeng Shi3; Rajendra Bordia1; Jianhua Tong1; Hai Xiao1; Fei Peng1; 1Clemson University; 2Advanced Manufacturing LLC; 3Rensselaer Polytechnic Institute
We report an ultra–fast sintering phenomenon of alumina under scanning laser irradiation, and a machine learning approach to predict the microstructure of such alumina. Using CO2 laser irradiation, we found that micrometer–sized alumina powder can be sintered close to full density within a few tens of seconds. The microstructure and sintering master curve of laser–sintered alumina were different from those of the furnace–sintered alumina. Since the microstructure of laser-sintered alumina is significantly different from the furnace-sintered ones, to predict alumina’s microstructure under laser sintering, we developed an elegant machine learning algorithm to predict the microstructure under arbitrary laser power. We name this algorithm, regression-based conditional generative adversarial networks (GANs) with Wasserstein loss function and gradient penalty (RCWGAN-GP). The RCWGAN-GP realistically regenerates the SEM micrographs under the trained laser powers. Further, it also accurately predicts the alumina’s microstructure under unexplored laser power.