Advanced Real Time Imaging: On-Demand Oral Presentations
Sponsored by: TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Alloy Phases Committee, TMS: Biomaterials Committee
Program Organizers: Jinichiro Nakano, MatterGreen; David Alman, National Energy Technology Laboratory; Il Sohn, Yonsei University; Hiroyuki Shibata, Tohoku University; Antoine Allanore, Massachusetts Institute of Technology; Noritaka Saito, Kyushu University; Anna Nakano, US Department of Energy National Energy Technology Laboratory; Zuotai Zhang, Southern University of Science and Technology; Candan Tamerler, University of Kansas; Bryan Webler, Carnegie Mellon University; Wangzhong Mu, KTH Royal Institute of Technology; David Veysset, Stanford University; Pranjal Nautiyal, University of Pennsylvania
Monday 8:00 AM
March 14, 2022
Room: Characterization
Location: On-Demand Room
In Situ Evidence of Dynamic Interactions between Droplets and Dendrites during Rapid Solidification of Immiscible Alloys: Jianrong Gao1; 1Northeastern University
The phase diagram of two metals with positive heat of mixing often show a liquid miscibility gap. When a homogeneous liquid is cooled to the binodal of the miscibility gap, it will be decomposed into two liquids of different chemical compositions. This liquid-liquid decomposition is known as liquid phase separation and has aroused fundamental and technical interest in the past decades. In this talk, I present in situ observations of rapid solidification of phase-separated metallic alloys using a high-speed optical camera. It was observed that droplets of a minority phase have strong and dynamic interactions with dendrites of a primary solid phase rapidly crystallizing from the majority liquid phase leading to acceleration or deceleration of dendrite growth kinetics during solidification. These dynamic interactions can be attributed to temporally and spatially dependent Marangoni convection associated with dissipation of latent heat released during rapid crystal growth in the phase-separated liquid mixture.
Dissolution Behavior of Non-metallic Inclusions in Refining Slag Observed Using Confocal Scanning Laser Microscopes: Ying Ren1; Lifeng Zhang2; Changyu Ren1; 1University of Science and Technology Beijing; 2Yanshan University
The dissolution of Al2O3 and SiO2 particles in CaO-Al2O3-SiO2 slags was investigated using confocal scanning laser microscope at the steel refining temperature. It was found that the rate-limiting step was the diffusion in the molten slag. For the dissolution of Al2O3 particles in CaO-Al2O3-based slags, the higher CaO/Al2O3 ratio was beneficial to improve the inclusion removal. For the dissolution of SiO2 particles in CaO-SiO2 based slags, the increase of CaO/SiO2 and the addition of 5% Al2O3 promoted the inclusion dissolution. The higher refining temperature, the faster dissolution of Al2O3 and SiO2 particles in CaO-Al2O3-SiO2 slags. A model related to dissolution driving force and slag viscosity was proposed to predict the dissolution rate of Al2O3 and SiO2 particles in CaO-Al2O3-SiO2 slags.
In Situ Observation and Investigation of the Wetting Behaviors of Mold Flux on Steel Substrate: Lejun Zhou1; Yang Yang1; Wanlin Wang1; Hao Luo1; Houfa Wu1; 1Central South University
There are multi-interphase phenomena occurring in the continuous casting mold, such as shell versus molten flux, inclusions versus molten steel, molten steel versus gas bubbles, etc., which makes the interfacial phenomena very complex. The interfacial property between liquid mold flux and steel has significant impact on the quality of casting slab. The slag entrapment in mold tends to cause severe defects on slab surface, especially for casting steels containing active alloy elements like Al, Ti, Mn, etc. Therefore, the wetting behaviors of mold flux on steel substrate were in situ observed and investigated using the sessile drop method. The microstructure and element distribution across the slag-metal interface were analyzed by SEM and EDS for further investigation of the relationship between the wetting behavior and chemical reaction at mold flux/steel interface. The results obtained in this study can provide a new sight to design mold flux and improve slab quality.
Ca2+ and pH Imaging during Dissolution of CaSiO3 into Aqueous Solution: Sakiko Kawanishi1; Hinako Nakayama1; Jun Kawano2; Takeshi Yoshikawa3; Hiroyuki Shibata1; 1Tohoku University; 2Hokkaido University; 3The University of Tokyo
Ca elution from the recycled steelmaking slag for both land and sea area is one of crucial issues because of the excess pH increase in the surrounding environment. However, a precise mechanism of Ca elution and the subsequent pH change has not yet been revealed. To provide a new methodology to access the mechanism, we demonstrated a simultaneous pH and Ca2+ imaging during the dissolution of CaSiO3 into aqueous solution by a fluorescence microscopy. Time revolution of Ca2+ and pH distributions around the CaSiO3 was successfully evaluated in the range of 0 – 40 ppm and 6.5 – 9.5, respectively. The rapid increase of both Ca2+ and pH was observed from the glassy phase compared with the crystalline phases. Details of the real time observation technique and the relationship between Ca2+ and pH will be presented in the symposium.
Evaluation of Interfacial Energy between Molten Fe- 18%Cr-9%Ni Alloy and Non-metallic Inclusion-type Oxides at 1873K: Tomoki Furukawa1; Noritaka Saito2; Kunihiko Nakashima2; 1The University of Tokyo; 2Kyushu University
The contact angles between three non-metallic inclusion-type oxide substrates, viz. Al2O3, MgO, and MgO⋅Al2O3, and molten Fe and molten Fe-based stainless steel (Fe-Cr-Ni alloy) were measured using the sessile drop method in Ar atmosphere at 1873K. The contact angles between molten Fe and oxide substrates ranged between 111° and 117°, while that between molten Fe-Cr-Ni alloy and substrates ranged between 103° and 105°. The wettability of the molten materials is related to the interfacial tension between the molten metals and each substrate. Thus, the interfacial tension between the molten metals and the non-metallic substrates was quantitatively evaluated using Young’s equation and the measured contact angles. Owing to the higher reactivity between molten Fe-Cr-Ni alloy and the substrates, the interfacial tension and energy between them were lower than those between molten Fe and the substrates.
In-operando Interactions of Refractory Materials with Ash/Slag from Mixed Feedstock Gasification: Anna Nakano1; Kristin Tippey2; Jinichiro Nakano1; Hugh Thomas3; Ömer Doğan3; Matthew Lambert4; Dana G. Goski4; 1U.S. Department of Energy National Energy Technology Laboratory/ NETL Support Contractor; 2National Energy Technology Laboratory; 3U.S. Department of Energy National Energy Technology Laboratory; 4Allied Mineral Products, LLC
Gasification utilizes a complex mixture of high temperature reactions to enable conversion of carbon feedstock to a syngas, which is used to produce electric power, synthetic fuels, and chemicals. The refractory liner that is used in a gasifier is required to withstand harsh high-temperature, high-pressure environments to protect the reactor. Under severe conditions, ash and/or molten slag originating from the carbon feedstock directly interacts with the refractory, causing materials degradation. The refractory service life limits the gasifier online availability, which negatively impacts production and energy efficiency, economics, and the environment. In this work, interactions of refractory materials with synthetic ashes from coal, biomass, and plastics were investigated at up to 1,200 °C in 64%CO-36%CO2. In-operando materials observations were enabled by utilizing the customized high-temperature environmental confocal scanning laser microscope system. Potassium tended to travel through the refractory materials upon heating, but no apparent surface degradation was noted at 800 °C.
Three-dimensional Time Evolution Behavior of Short Fatigue Crack Morphology and Crack Closure in Ti-6Al-4V Alloy Assessed Using High-energy Imaging Type CT: Valary Tubei1; Hiroyuki Toda1; Akihisa Takeuchi2; Masayuki Uesugi2; 1Kyushu University; 2Japan Synchrotron Radiation Research Institute
High-energy imaging type CT technique was utilized to locally observe the three-dimensional (3D) time evolution behavior of a short fatigue crack and crack closure in Ti-6Al-4V alloy. The microstructure, 3D crack morphology together with the occurrence of crack closure were readily visualized at a spatial resolution level of 130 nm attained in this study. The highly torturous 3D cracks were due to crack interaction with the heterogenous 3D local microstructural features. These complex crack morphologies consisted of deflections, facet paths and overlapped/branched crack. It was elucidated that these different crack path morphologies with varied extents of crack surface roughness and plastic deformation at the crack tips control the closure behavior along the crack front. With crack growth, crack tilting and twisting with respect to the overall crack growth direction were observed in some locations along the crack front which influenced the crack closure behavior and subsequently the crack growth rate.
Simultaneous Extraction of Nickel and Vanadium from Petroleum Byproducts: Jinichiro Nakano1; Anna Nakano1; Ryu Takekoh2; Hugh Thomas3; 1US Department of Energy - National Engergy Technology Laboratory; 2IT-Related Chemicals Research Laboratory, Sumitomo Chemical Co., Ltd.; 3US DOE National Energy Technology Laboratory
Petcoke slag is a petroleum byproduct originating from industrial processes such as gasification, which utilizes petcoke as carbon feedstock. Slag forms in the gasification reactor from ash impurities from the feedstock, most of which is currently dumped in landfill sites. The petcoke slag, however, commonly exhibits high concentrations of nickel and vanadium (as high as 6 wt.% and 20 wt.%, respectively), which are critical to many clean energy applications, including advanced batteries and high-performance alloys. In this work, segregation behavior of the nickel and vanadium from the petcoke slag was investigated under carbothermal conditions at up to 1,500 °C. Nickel tended to form either metallic nickel or carbide while vanadium formed vanadium oxide. Easy separation of those materials was achieved as the segregation occurred ‘above’ the slag surface.
In-situ Observation of SO2 Gas Formation at the Magnetite/Matte Interface at 1200℃: Seung-Hwan Shin1; Sakiko Kawanishi1; Sohei Sukenaga1; Junichi Takahashi2; Hiroyuki Shibata1; 1Tohoku University; 2SMM Co., LTD
The stagnation of solid magnetite at the interface between slag and matte (Cu2S-FeS) is one of the big issues in the copper smelting process using a flash furnace. The magnetite inhibits the absorption of the suspended matte in the slag phase into the matte phase, which leads to copper loss. Therefore, the rapid removal of the magnetite by the reaction with the matte can greatly contribute to reducing the copper loss. In this study, we aim to clarify the reaction behavior of the interface between magnetite/matte by in-situ observation through the magnetite thin film. The formation of SO2 gas bubbles was observed at the interface and the size of bubbles was decreased by the increase of FeS concentration in the matte. Furthermore, we clarified that the remained gases at the interface could be a factor that decreases the reaction rate between magnetite and matte.
Real Time Quantification of Nickel, Cobalt, and Manganese Concentration Using Ultraviolet-visible Spectroscopy -- A Feasibility Study: Monu Malik1; Ka Ho Chan1; Gisele Azimi1; 1University of Toronto
In the present study, the feasibility of the real-time quantification of nickel, cobalt, manganese, and lithium concentration was investigated using Ultraviolet-Visible Spectroscopy as a replacement for the conventional method to measure the concentrations of these elements in battery and other applicable industries. Ultraviolet-visible spectroscopy is one of the most effective, flexible, inexpensive, and simplest analytical techniques to measure species concentration. The technique has a wide range of applications such as wastewater treatment to colloidal nanoparticle characterization. To carry out the study, samples with different concentrations of individual elements and composites were prepared and analyzed using an Ultraviolet-Visible spectrometer. Mathematical relationships were defined between concentration and absorbance, and calculated concentrations were compared with ICP-OES results. The effect of various parameters such as elements concentration, path length, number of elements in the solution, density, and pH on absorbance was analyzed to verify the feasibility of the method in the industry.
Real Time Observation of Reactive Spreading and Interfacial Reactions between Liquid AlNi Alloy and Solid Ni: Youqing Sun1; Ensieh Yousefi1; Anil Kunwar2; Nele Moelans2; David Seveno1; Muxing Guo2; 1KU Leuven; 2Silesian University of Technology
Real time observation of reactive wettability in liquid Al-Ni alloy/solid nickel (Ni) system can provide important insights into the mechanisms involved in high temperature processing techniques. In this study, the spreading of Al-rich Al-Ni alloy on Ni from 750 to 950 °C is investigated by using Thermo-Optical Dynamic Wetting Apparatus(TODWA). Wetting experiments are conducted in a well-designed T-junction tube, in which a gas tight and oxygen free environment is guaranteed. The liquid alloy and the substrate are heated separately (non-contact heating), and the oxidation layer on the liquid alloy surface is removed by squeezing it out against the special injector. The phase formation sequence and the phase growth mechanism at the Al-Ni/Ni interface are characterized by conducting capillary suction experiments. It was found that Al3Ni phase was the primary phase formed during isothermal holding stage. The effects of interfacial reactions on spreading and final wettability were also accounted.
Evaluation of Dynamic Wetting Properties of Si/C Interface: Yoshiki Takeuchi1; Shun Ueda1; Takeshi Yoshikawa1; Kazuki Morita1; 1The University of Tokyo
One of the manufacturing processes for ceramic matrix composites composed of silicon carbide fiber-reinforced silicon carbide matrix composites (SiC/SiC-CMC) is the RMI (Reactive Melt Infiltration) method, where molten silicon(Si) is impregnated into the precursor composed of SiC fiber and porous carbon(C). In order to optimize the manufacturing process by RMI method, it is essential to clarify the highly reactive Si-C interface phenomena. In the present study, dynamic contact angle measurements between Si and various types of C were performed to investigate the interfacial phenomena between Si and C. As a result, it was found that the contact angle decreased with various rate depending on the type of C substrate. Moreover, microscopic observation of the interface during and after the reaction was conducted to clarify the relationship between wettability and substrate properties such as C morphology and surface properties.