Powder Materials Processing and Fundamental Understanding: Powder Material Studies
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
Wednesday 2:00 PM
March 2, 2022
Room: 263C
Location: Anaheim Convention Center
Session Chair: Ruigang Wang, Michigan State University; Isabella Van Rooyen, Pacific Northwest National Laboratory
2:00 PM
Redox Chemistry of Surface-engineered CeO2 Nanocrystals: Catalytic and Electrochemical Applications: Yifan Wang1; Zhen Wei1; Ruigang Wang1; 1The University of Alabama
Catalyst-support interaction and interface play a critical role in heterogeneous catalysis. CeO2 along with other oxides constitutes an important class of catalyst supports that can exchange oxygen rapidly under variable reducing or oxidizing conditions, which is mainly accomplished by a reversible valence change of the cerium ions (2Ce(IV)O2 -> Ce2(III)O3 + 1/2O2) with formation or elimination of oxygen vacancies. Oxygen exchange or charge transfer during the reduction and oxidation (redox) processes are essential steps for many catalytic reactions at elevated temperatures. In this talk, we will present some recent progress on (1) synthesis and characterization of shape/crystal structure-controlled CeO2 support materials, (2) chemical etching surface modification of CeO2, (3) electrospinning synthesis of thermally stable CeO2 nanofibers, and (4) understanding the catalyst-support interaction and support promoting effect for many industrial catalytic and electrochemical applications such as in vehicle exhaust clean-up, carbon dioxide capture, and host materials of Li-S battery.
2:20 PM Invited
Particle-based Nanostructured Ceramics for Tailored Functional and Mechanical Properties: Diletta Giuntini1; Buesra Bor2; Alexander Plunkett2; Berta Domenech2; Gerold Schneider2; 1Eindhoven University of Technology; 2Hamburg University of Technology
Nanoarchitected and nanostructured materials combine the unique features of nano-sized building blocks and their organization in long-range order patterns to foster new properties up to the macroscale. A successful bottom-up approach to produce many such architectures is self-assembly of nanoparticles. Many functional applications open up, in catalysis, battery electrodes, transformer cores, optoelectronics, and more. However, some challenges still stand in the way of the implementation of self-assembled nanoparticle-based materials into devices: upscaling and upsizing their production, and enhancing their mechanical behavior. This talk will present strategies to tackle both these challenges, together with with the high potential of nanostructured supercrystalline materials as building blocks for bioinspired hierarchical structural materials.
2:50 PM
Silicon Oxycarbide Coatings on Zirconia Microspheres Using a Fluidized Bed Coating Process: Kathy Lu1; Sanjay Singh1; 1Virginia Polytechnic Institute and State University
In this study, YSZ microspheres were successfully coated with a polymer derived ceramic to a thickness of ~110 µm using a fluidized bed coating process. The influence of the coating parameters, such as coating solution rheology and temperature, on the coating process was investigated and the underlining coating mechanisms were elucidated. Simulations provided gas and particle velocity distribution data that cannot be measured experimentally. During pyrolysis, depolymerization and hydrocarbon loss occurred between 400-600 °C. The SiOC coating shrank significantly during pyrolysis with a final thickness of 40-55 µm. The phase separation of the coating layer led to the formation of SiOC, SiO2, SiC, and graphite. This work provides a promising method of creating more irradiation resistant nuclear fuel coatings.
3:10 PM
Rapid Solidification of Ultrasonically Atomised Aluminium Melt: Shazamin Shahrani1; Tungky Subroto2; Dmitry Eskin2; Iakovos Tzanakis1; John Durodola1; Georges Salloum-Abou-Joude3; Abhinav Priyadarshi1; 1Oxford Brookes University; 2Brunel University; 3Constellium
Recent developments in ultrasonic atomisation (UA) towards the production of Additive Manufacturing (AM) grade metal powders has been promising. This process involves the use of ultrasonic transducer operating at 17.8 kHz, where the titanium sonotrode atomises poured molten pure Aluminium and AlSi11Fe4 at temperatures up to 720°° C through standing wave vibrations. Different powder batches were produced through variations in sonotrode angle, sonication power, and landing distance from the tip of sonotrode. Rapid solidification of atomised metal droplets in air resulted in mixed quality of powders including AM desired spherical shapes, as well as elongated and branching teardrops, with the powder size ranging from 40 to 300 µμm . Energy dispersive x-ray spectroscopy (EDS) was also performed to confirm any contamination or changes in chemical composition of the materials used. This method would help improve characterisation of aluminium alloy powders produced through UA.
3:30 PM Break
3:50 PM
Understanding Mechanisms Behind Morphological Changes in Gas Atomized Powders after Laser Irradiation: Jonathan Skelton1; Connor Headley1; Eli Sullivan1; James Fitz-Gerald1; Jerrold Floro1; 1University of Virginia
This research focuses on morphological changes observed in Al-Cu eutectic alloy powders (1-100μm diameter) irradiated with a CW laser diode (450 nm) on glass substrates. Particles were characterized with scanning electron microscopy before and after irradiation. Changes in the eutectic microstructure clearly demonstrate that melting occurred during laser irradiation, but under these conditions, the particles melted while fully contained within the thin, contiguous native oxide shell. Upon cooling, differential thermal contraction promotes post-buckling instabilities within the shell that severely deform the morphology of the solidified powder particles. The formation of more severe features in smaller particles is surprising, and suggests a dynamic interaction between the moving solidification front and the buckling oxide shell. Similar behavior is seen in Al-Cu eutectic powder particles near the edges of melt tracks in laser powder bed fusion, with implications for powder recycling. Support of the NSF under grant DMR-1663085 is gratefully acknowledged.