Powder Materials Processing and Fundamental Understanding: Synthesis
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Powder Materials Committee
Program Organizers: Elisa Torresani, San Diego State University; Kathy Lu, University of Alabama Birmingham; Eugene Olevsky, San Diego State University; Ma Qian, Royal Melbourne Institute of Technology; Diletta Giuntini, Eindhoven University of Technology; Paul Prichard, Kennametal Inc.; Wenwu Xu, San Diego State University
Tuesday 8:00 AM
March 21, 2023
Room: 25B
Location: SDCC
Session Chair: Olivia Graeve, University of California, San Diego; Stephen Heywood, Montana State University
8:00 AM
Combustion Synthesis of ZrC-TiC Composite Nanoparticle by Self-Propagating High Temperature Synthesis (SHS) in ZrO2 – TiO2 – Mg / Al - C System: Mehmet Bugdayci1; Ozan Coban2; 1Yalova University; 2Istanbul Gedik University
In this study, ZrC-TiC composite nanoparticle was synthesized by SHS method using oxide raw materials, carbon black and Mg and Al reductants. For SHS processes, composite charge stoichiometries were optimized for Mg usage and the usage of Al and Mg was compared. The stoichiometries of the chemicals used in the processes applied to remove undesired by-products and the concentration of acids were also optimized the most accurate process steps were determined for the purification of the SHS product. A novel route was established for purification of SHS product obtained by Al usage as reductant. Characterization was performed with XRD analysis. The results showed that commercial purity ZrC-TiC powder with high surface area could be synthesized by using both reductants. The results revealed that Mg is a better reductant, but Al with lower cost when compared to Mg is also a suitable reductant, although it increases the process steps.
8:20 AM
Design and Synthesis of Alkaline-earth Doped Hexaborides with Sodium and Potassium Dopants: Alan Hirales1; Justin Nakamura1; Olivia Graeve1; 1University of California San Diego
We present the synthesis and crystallography of two metal hexaboride solid solutions, Ca1-xMxB6 and Sr1-xMxB6 (x = 0, 0.1, 0.3, 0.5), where M is Na or K; and show their evolution as the experimental concentration, x, is increased. The hexaborides were synthesized by solution combustion synthesis with a subsequent washing by HCl. Results on structure by X-ray diffraction and scanning electron microscopy showed minimal changes in lattice parameters, particle shapes and interplanar spacings. Dopant concentration analyses were carried out using inductively coupled plasma mass spectrometry, showing an atomic percentage from 1% to 3%, depending on the dopant metal, and resulting in a relatively small dopant level increase as the precursor concentration of the dopant increased. Additionally, Ca1-xMxB6 compounds show a lower ion incorporation for both dopants compared to Sr1-xMxB6. Further research is projected to determine the effect of dopant on the electrical properties of hexaboride solutions.
8:40 AM
Scalable Synthesis of Flowable Porous Copper Powders and Nanoscale Welding for High Surface Area 3D Printed Parts: Natalya Kublik1; Stanislau Niauzorau1; Bruno Azeredo1; 1Arizona State University
Size-dependent properties have brought nanoporous metals to scientific community attention due to their capacity to incorporate unique chemical, optical, and mechanical properties to larger scales. Envisioning additive manufacturing of high surface area and load-bearing, this study examines essential parameters of feedstock synthesis, scalability, flowability, and electrical conductivity. Here, nanoporous copper powders are safely fabricated via chemical dealloying in a 0.1 kg/hr scale, with excellent reproducibility, low oxygen content, moderate flowability, ligament sizes of 46 nm, and free of precipitates. Next, towards the fabrication of porous electrodes, an in-situ resistance measurement during heat in reducing atmosphere of compacted powders is performed, resulting in single digit resistance after cooling and oxygen introduction, attesting the oxide layer decomposition, nanoscale welding, and electrical conductivity through the part. Lastly, focused Ion Beam cross-sections also show preserved porosity and surface area of parts sintered at temperatures as low as 1/3 of Cu melting point.
9:00 AM Invited
Synthesis and Crystallography of High Entropy Metal Carbides: A New Class of Ultrahigh Temperature Ceramics: Olivia Graeve1; 1University of California San Diego
We have implemented a novel solvothermal synthesis process for the preparation of high entropy metal carbide (HEMC) powders. Specifically, mixtures of Mo-Nb-Ta-V-W carbides were produced by mixing metal chlorides and carbon powder in the presence of molten lithium. We have produced binary, ternary, quaternary, quinary, and senary metal carbides through systematic manipulation of elemental composition. Solid solutions have been confirmed by a combination of X-ray diffraction / Rietveld refinement and energy dispersive spectroscopy. Subsequently, spark plasma sintering (SPS) was used to obtain dense specimens of these compositionally complex ceramics. Phase composition and structure of the sintered specimens, density, and elemental distribution were analyzed. Grain boundary composition was also explored using atomic-resolution transmission electron microscopy. We will also describe preliminary results on the synthesis of hexaboride materials by similar techniques as the HEMC powders and present a comparative analysis between the techniques.
9:30 AM Break
9:50 AM
Tailored Morphology of TaC Nanoparticles by Introduction of Transition Metal Dopants: Stephanie Ortega1; Jixuan Dong1; Jamie Doan1; Katada Siraj1; Olivia Graeve1; 1University of California San Diego
TaC is an ultra-high-temperature ceramic (UHTC) which is known for its high melting temperature (~4100 K) and outstanding hardness (15-19 GPa), making it particularly relevant for engineering applications where environments are harsh. However, the use of TaC is limited because of defects and unwanted phases which form during typical fabrication techniques such as sintering. The unwanted phases and defects in TaC, particularly porosity, have been linked to a decrease in mechanical properties. We hypothesize that faceted morphologies of TaC nanoparticles help in the manufacture of less porous structures after sintering, as well as prevention of creep deformation due to interlocking of faceted grains. In this study, doped TaC nanoparticles with faceted morphologies have been synthesized through a solvothermal method and subsequently spark plasma sintered to obtain samples for characterization of mechanical properties and grain boundary structure. Dopants included iron, cobalt, nickel and titanium.
10:10 AM
LLZO Powder Synthesis & Design for Maintaining Li Stoichiometry in Powders and Dense Membranes: Stephen Heywood1; Stephen Sofie1; David Driscoll1; 1Montana State University
Lithium lanthanum zirconium oxide garnet (LLZO) as a solid-state lithium ion conducting electrolyte has immense promise for solid-state-batteries owing to its high lithium conductivity and chemical stability with lithium metal. Given the range of ceramic materials processing constraints including milling, calcination, and sintering at temperatures above 1000 Celsius, lithium volatility can drive deleterious phase formation. This study examined the effect of excess lithium concentration, and phase formation pathways via XRD in-situ and post sintering , coupled with TGA and EIS to elucidate mechanisms that reduce the processing sensitivities of LLZO for the scalable production of LLZO powders. Processing sensitivities ameliorated via direct incorporation of excess lithium within the LLZO lattice provides a key advantage towards the improved suppression of lithium volatilization in ceramic aqueous slurry processing for both porous electrodes and dense separators in solid-state-batteries. Further, LLZO scaffold based cells were fabricated into 2032 buttons and performance will be reported.
10:30 AM
Fabrication of Nanoporous Aluminum Powders via Thermal and Chemical Processing: Jodie Baris1; Jonah Erlebacher1; 1Johns Hopkins University
Nanoporous aluminum possesses a highly reactive and high surface area, making it useful for many applications. Most current methods of fabricating nanoporous aluminum use electrochemical approaches that are energy intensive and require bulk metal precursors. Here, we present a new method to generate nanoporous aluminum powder from Zn50Al50 powder using a single-step heating process followed by chemical etching. This technique utilizes the miscibility gap in the phase behavior of the Zn-Al system to heat and anneal samples such that a solid solution forms, then quench the powders to drive phase separation via spinodal decomposition. This results in a bicontinuous microstructure with separate Al and Zn domains with length scales controllable between 30-100 nanometers. A combination of acid etchants can remove Zn to generate nanoporous Al powder with minimal residual surface oxide. Methods to process and tune the microstructure will be presented, along with characterization by SEM, EDS and TEM.
10:50 AM
Synthesis of Ti-Al Intermetallic Compound Fine Powder Using Shuttle of Proportionation and Disproportionation Reactions in Molten Salt: Terigele Terigele1; Xin Lu1; Osamu Takeda1; Hongmin Zhu1; 1Tohoku University
Titanium alloys are widely used in industrial applications due to their excellent properties such as low density, high specific strength, and high corrosion resistance. However, the fabrication and production costs of titanium alloys are high. Powder metallurgy is considered as one promising approach to reduce the production costs of titanium materials. However, the conventional preparation processes of titanium and its alloy powders are generally complicated and high cost. In this study, a novel synthesis method of Ti-Al fine powder was developed using shuttle of disproportionation and proportionation reactions of titanium ions in molten salts. It was found that uniform Ti-Al intermetallic compound powder was produced from titanium and aluminum bulk metals. Furthermore, the composition of produced Ti-Al compound powder, in form of Ti2Al5, TiAl2 and TiAl3, depends on the preparation temperature, but with less dependence in the composition of solvent molten salt.