Liquid Metal Research Articles

Scaling of HeatLMD-simulated impurity outflux from COMPASS-U liquid metal divertor

Abstract The Liquid Metal Divertor (LMD) concept offers a promising solution to manage extreme heat loads in plasma devices. This study presents predictive simulations using the HeatLMD model for the COMPASS-U tokamak with a full toroidal liquid metal divertor, expected to achieve reactor-relevant divertor heat flux densities. We derive the scaling of the Li|Sn outflux over 7 assumed independent parameters, transferable to other tokamaks. Its transport to LCFS (via ERO2.0) and its radiation (via Aurora and FACIT) predict acceptably low lithium concentration and negligible plasma cooling. However, for tin, the medium power scenario requires backside cooling beyond the capability of ITER-like water-cooled divertor, though a temporary heat absorber can approximate this for a 1-second plasma pulse. For incident divertor power exceeding 2 MW and strike point Te<10 eV, HeatLMD predicts significant tin plasma radiative disruption.

General Approach to Hydrolysis Resistive Aluminum Nitride and Its High-Performance Thermal Interface Materials.

Aluminum nitride (AlN), noted for its excellent thermal conductivity and exceptional electrical insulation, presents a promising alternative to traditional ceramic particles in thermal interface materials (TIMs). However, its broader adoption in practical applications is limited by performance degradation due to the vulnerability of its crystal structure to ubiquitous moisture. This study introduces a dual solution, utilizing a mechanochemical method to design a dense outer layer of Galinstan liquid metal (LM) that simultaneously enhances AlN's resistance to hydrolysis and improves its thermal performance in TIM applications. The high surface free energy of the LM layer imparts hydrophobic properties to the AlN surface and, combined with outer metal oxides, forms a dual-layer protective barrier that prevents water penetration, significantly enhancing the TIM's long-term stability in high-humidity conditions. Additionally, the LM layer at the interface improves the thixotropic properties of the TIM and enhances interfacial heat transport through the bridging effect of the LM, resulting in improved rheological mobility and thermal conductivity of the composite material. This win-win surface modification strategy opens opportunities for the practical and durable application of AlN in widespread electronic thermal management.

Identifying patterns in the structural-phase transformations when processing oxide doped waste with the use of carbon reducer

The object of this study is the structural and phase transformations during the carbon reduction of tungsten high-speed steel slag in order to obtain a resource-saving alloying additive. The problem is the loss of precious elements when obtaining and using alloying material from man-made raw materials. Solving the problem is related to the definition of technological parameters to enable the reduction of losses of the corresponding elements. As a result of increasing the degree of scale reduction from 33 % to 72 % and 85 %, the strengthening of the manifestation of the solid solution of carbon and alloying elements in α-Fe relative to FeWO4, FeO and Fe3O4 was revealed. Fe3C, WC, W2C, FeW3C, Fe3W3C, Fe6W6C, VC, V2C, Cr3C2, Cr7C3 and Cr23C6 also appeared. Along with this, rounded and multifaceted particles with different chemical composition and the formation of a spongy microstructure were found. It was established that the most acceptable degree of recovery is 85 %. But achieving a recovery rate of 72 % is also sufficient. This is explained by the fact that the residual carbon in the carbides provides an increased reducing capacity, which is realized during the further reduction of oxides in the liquid metal during alloying. The spongy microstructure results in faster dissolution in contrast to standard ferroalloys, which provides a reduction in melting time while reducing spent resources. No phases with an increased tendency to sublimation were found in the obtained alloying material. That is, no additional conditions are needed that restrain the loss of alloying elements during evaporation with a gaseous phase, which provides an increase in the degree of extraction of the corresponding elements. The properties of the resulting alloying material make it possible to use it in metallurgical production when smelting alloyed steel grades in an electric arc furnace, the composition of which does not have strict restrictions on the carbon content

Design Optimal Riser Size for Reducing Shrinkage Defect in 1100 Aluminum Alloy Sand Casting Process

This research aims to design a sprue system for aluminum castings in sand pores for a basic form prototype in metal casting, which is a one-piece pattern with a parting line. There are several types of liquid metal gating systems available. In the design, variables were specified regarding the height of the sprue, the cross-sectional area of the sprue, the cross-sectional area of the reservoir, the cross-sectional area of the runner, and the cross-sectional area of the gating. The riser size was used as a comparison variable. Following study and design, an experiment was conducted to cast the actual casting and to analyze the behavior simulation using Cast-Designer to determine a solution. In the simulation, the following results were found: the time taken to add liquid metal; the flow behavior of liquid metal; the metal hardening time; and the formation of shrinkage cavities in the casting. Based on the results of casting experiments and behavioral simulations, it was demonstrated that the large riser significantly reduced the shrinkage of the actual casting.

An Atomic‐Scale Explanation for The High Selectivity Towards Carbon Dioxide Reduction Observed On Liquid Metal Catalysts

AbstractThe low‐temperature liquid metals Ga‐In and Ga‐Sn have previously showcased >95 % selectivity towards the electrochemical reduction of CO2 to formate, occuring only when the alloys are melted, not solid. Here, density functional theory molecular dynamics and metadynamics simulations reveal that CO2 does not directly adsorb to the Ga‐alloy surface, but instead is reduced indirectly by reaction with an adsorbed hydrogen. The reaction barrier is vastly more favourable when this process occurs at In or Sn sites (average: 0.26 eV), than when it occurs on Ga (average: 0.47 eV). However, there is no difference in barrier between solid and liquid surfaces. Instead, we find that Hads is mobile only on the liquid surface, travelling due to the motion of the liquid beneath. This process drives Hads to In/Sn sites, allowing low‐barrier CO2 reduction to occur only on the liquid. Therefore, the dynamic motion of liquid metal catalysts can underpin their unique reactivity. The result has far reaching implications for any protonation reaction conducted with a liquid metal catalyst.

Design a Gating System for an Aluminum Cast Three-Way Pipe in Sand Casting

The study of aluminum casting work with market demand in the metal casting industry, designing a gating system in aluminum casting using a three-way pipe-shaped sand mold workpiece as a basic shape template in metal casting, namely a flat-face core box with a core. The gating system has a metal inlet with design variables including the pouring height, pouring basin cross-sectional area, rest basin cross-sectional area, running system cross-sectional area and inlet cross-sectional area. From the studying and designing, actual casting experiments were conducted and simulation behavior was analyzed using Cast-Designer software to make decisions and find appropriate design approaches from analyzing simulation results including liquid metal filling time, molten metal flow behavior, metal solidification time and shrinkage porosity formation of the workpiece. The results of the casting experiment and behavior simulation were able to cast the pipe workpiece which is a flat-face core box mold. The analysis results from the software can be used for actual pouring, where the fully cast mold successfully produced a complete workpiece. This can be a guideline for future improvements to reduce the shrinkage of actual cast workpieces.

Multiphysics Simulation and Concept of an Electromagnetically Control Volumetric Pixel as a Step Towards a Shape Morphing Composite

Abstract Constant development of robotics forces scientists and engineers to work on robots that are more visually and rigidly compatible with the environment around us. To make this possible, new flexible structures are necessary that enable programmatic shape change. To meet this need, in this work we present the concept and modelling methodology of a new structure enabling shape change using electromagnetic forces produced in liquid metal conductor and its stiffening using a granular jamming mechanism. This work presents the structure concept, the description of modelling methodology and empirical validation including the magnetitic field, scanned by magnetic field camera, and displacement distribution.

Replacing the Gallium Oxide Shell with Conductive Ag: Toward a Printable and Recyclable Composite for Highly Stretchable Electronics, Electromagnetic Shielding, and Thermal Interfaces.

Liquid metal (LM)-based composites hold promise for soft electronics due to their high conductivity and fluidic nature. However, the presence of α-Ga2O3 and GaOOH layers around LM droplets impairs conductivity and performance. We tackle this issue by replacing the oxide layer with conductive silver (Ag) using an ultrasonic-assisted galvanic replacement reaction. The Ag-coated nanoparticles form aggregated, porous microparticles that are mixed with styrene-isoprene-styrene (SIS) polymers, resulting in a digitally printable composite with superior electrical conductivity and electromechanical properties compared to conventional fillers. Adding more LM enhances these properties further. The composite achieves EMI shielding effectiveness (SE) exceeding 75 dB in the X-band frequency range, even at 200% strain, meeting stringent military and medical standards. It is applicable in wireless communications and Bluetooth signal blocking and as a thermal interface material (TIM). Additionally, we highlight its recyclability using a biodegradable solvent, underscoring its eco-friendly potential. This composite represents a significant advancement in stretchable electronics and EMI shielding, with implications for wearable and bioelectronic applications.

Controlled Nanopore Sizes in Supraparticle Supports for Enhanced Propane Dehydrogenation with GaPt SCALMS Catalysts.

The efficient immobilization of GaPt liquid metal alloy droplets onto tailored supports improves catalytic performance by preventing coalescence and subsequent loss of active surface area. Herein, we use tailored supraparticle (SP) supports with controlled nanopores to systematically study the influence of pore sizes on the catalytic stability of GaPt supported catalytically active liquid metal solution (SCALMS) in propane dehydrogenation (PDH). Initially, GaPt droplets were prepared via an atom-efficient and scalable ultrasonication method with recycling loops to yield droplets <300 nm. Subsequently, these droplets were immobilized onto SiO2-based SPs with controlled pore sizes ranging from 45 to 320 nm. Catalytic evaluations in PDH revealed that GaPt immobilized on SPs with larger pores demonstrated superior stability over 15 h time-on-stream evidenced by reduced deactivation rates from 0.046 to 0.026 h-1. Nanocomputed tomography and identical location SEM confirmed the successful immobilization of GaPt droplets within the interstitial sites formed by the primary particles constituting the SPs. These remained unchanged before and after the catalytic reaction, demonstrating efficient coalescence prevention. Our findings underscore the importance of support pore size engineering for improving the stability of GaPt SCALMS catalysts and highlight, particularly, the high potential of using SPs in this context.

Liquid metal catalyst for ammonia synthesis at low pressure

Liquid metal catalyst for ammonia synthesis at low pressure

Variation of Surface Tension of Liquid Metal with Fluorides in Tungsten Inert Gas Welding

Real-time measuring and obtaining surface tension of liquid metal during the arc welding process is critical for studying the behavior of the weld pool, such as Marangoni flow and flow velocity. The dynamic variation of surface tension of weld pool during tungsten inert gas welding process with and without fluoride flux was measured by weld pool oscillation sensing system, and the effect of fluoride flux on surface tension and pool behavior was analyzed. The results show that the surface tension gradient of liquid metal can convert from a negative to a positive value in a critical arc time. The flow velocity of liquid metal and critical arc time significantly increased and decreased, respectively, with fluoride flux. The variation of surface tension, flow velocity, and critical arc time with fluoride flux was induced by arc temperature increasing.

Flexible Continuum Robot with Variable Stiffness, Shape‐Aware, and Self‐Heating Capabilities

Conventional continuum robots have outstanding flexibility and dexterity. However, when the robot needs to interact with the environment, the softness may affect the performance of the robot. Especially in transport tasks, the softness of continuum robots can lead to handling failures and drastic drops in precision. The variable stiffness continuum robot combines the advantages of flexibility and rigidity, which is conducive to expanding the application scenarios of flexible continuum robots. This article proposes a flexible continuum robot that simultaneously realizes variable stiffness, shape‐aware, and self‐heating functions using liquid metal. The low‐temperature phase transition property of liquid metal is utilized to realize the variable stiffness function; the overall stiffness of the robot can reach the range of 18.5–183 N m−1, which can realize a tenfold stiffness gain. The conductivity of liquid metal is utilized to develop the shape‐aware function, and the monitoring accuracy is within 5%. At the same time, this article utilizes the liquid metal's resistive thermal effect to realize heating function, so that the robot no longer needs heating systems such as heating wires and can realize the phase transition by energizing itself. Based on this design, the robot arm can realize the transition between maximum and minimum stiffness within 240 s.

Simulation of Dendrite Remelting via the Phase-Field Method

The solidification of alloys is a key physical phenomenon in advanced material-processing techniques including, but not limited to, casting and welding. Mastering and controlling the solidification process and the way in which microstructure evolution occurs constitute the key to obtaining excellent material properties. The microstructure of a solidified liquid metal is dominated by dendrites. The growth process of these dendrites is extremely sensitive to temperature changes, and even a small change in temperature can significantly affect the growth rate of the dendrite tip. Dendrite remelting is inevitable when the temperature exceeds the critical threshold. In this study, a temperature-induced-dendrite remelting model was established, which was implemented through the coupling of the phase field method (PFM) and finite difference method (FDM). The transient evolution law of dendrite remelting was revealed by simulating dendritic growth and remelting processes. The phase field model showed that the lateral dendrites melt first, the main dendrites melt later, and the main dendrites only shrink but do not melt when the lateral dendrites have not completely melted or the root is not broken. The long lateral branches break into fragments, while the short lateral branches shrink back into the main dendrites. The main dendrites fracture and melt in multiple stages due to inhomogeneity.

Enhanced casein organohydrogel coating with the liquid metal catalyst for electric leather in human-machine interaction

Leather’s durability and multi-level structure make it an excellent substrate for electronics. Integrating leather with modern electronic technology to create electronic leather is becoming increasingly popular. However, significant challenges remain, such as adhering conductive media to leather, their penetration and dispersion, and the complexity of preparation. This study presents a new strategy for fabricating electronic leather by combining leather with a casein-based organic hydrogel using coating chemistry techniques. This hydrogel is simple to prepare and exhibits excellent biocompatibility and self-adhesive properties, offering a promising approach to overcome these challenges. Here, we designed casein-stabilized core-shell liquid metal-based catalysts and utilized acrylamide (AM), 2-acrylamido-2-methylpropane sulfonic acid (AMPs), CNTs, and glycerol (Gly) to achieve in situ organohydrogel formation on leather under mild conditions (60 s, 25 °C). The resulting organohydrogel-coated material exhibits outstanding stretchability (tensile stress: 70.3 kPa, tensile strain: 1491.8 %), rapid response (423 ms), and high sensitivity (GF: 7.67) as a strain sensor. This substrate can be employed in designing flexible wearable electronic gloves, facilitating seamless information interaction between humans and devices. This innovation demonstrates significant potential in enhancing the functionality of leather as a wearable electronic device. Combining leather’s natural properties with cutting-edge organohydrogel technology is promising to revolutionize the wearable electronics industry, potentially creating highly versatile and multifunctional electronic skins.

Comparative Study on the Liquid Metal Embrittlement Susceptibility of the High-Si Advanced High-Strength Steel with EG and GA Zn Coatings

The Zn-coated high-Si advanced high-strength steel (AHSS) tends to suffer Zn-assisted liquid metal embrittlement (LME) during the resistance spot welding (RSW) process. In this study, the LME behaviors of electrogalvanized (EG) and galvannealed (GA) high-Si steels were comparatively investigated. The maximum lengths of the LME cracks at the shoulder and center of the spot weld were approximately 366.6 μm and 1486.5 μm, respectively, for the EG yet 137.0 μm and 1533.3 μm, respectively, for the GA high-Si steels. Additionally, all EG and GA welded joints were etched to measure the nugget size. It was found that the increased welding current could aggravate the formation tendency of the LME cracks for both the EG and GA high-Si steels. Furthermore, the statistical results revealed that the electrogalvanized high-Si AHSS exhibited a relatively higher LME susceptibility than the galvannealed high-Si AHSS. It was deemed that the internal oxidation produced during the annealing before the Zn coating was the crucial factor that led to the difference in the LME susceptibilities for the EG and GA high-Si steels.

Construction of a mathematical model of turbulent heat and mass transfer processes for the case of electron beam melting of titanium alloy casts

This paper describes a mathematical model built for turbulent heat and mass transfer processes in the case of electron beam melting of titanium alloy ingots. The object of research is the conditions that ensure the quality of ingots. The model makes it possible to calculate the distribution of hydrodynamic flows in the liquid metal and temperature fields in the ingot, to determine the profile of the metal crystallization front, taking into account the interphase transition zones. The model solves the problem of finding the necessary melting regimes of ingots by calculation, in contrast to high-cost natural experiments. The thermal and hydrodynamic processes during the melting of a cylindrical ingot with a diameter of 110 mm of the newest titanium alloy Ti-6Al-7Nb for medical use were calculated and its melting parameters were determined. The small diameter of the ingot significantly facilitates its further machining. The geometry of the two-phase zone of the liquidus-solidus transition, which determines the crystallization front of the metal, was calculated. The position and geometry of this front greatly affects the quality of ingot formation and the concentration of the distribution of alloying elements and the homogeneity of the metal across its volume. A sufficiently flat crystallization front has been obtained, under which the given conditions are ensured. It was found that heat transfer in the liquid phase of the metal is mainly caused by heat and mass transfer due to its movement, and heat and mass transfer significantly depends on the power of the electron beam and its distribution on the surface of the bath. According to the calculated regimes, at the Institute of Electric Welding named after E. O. Paton, the National Academy of Sciences of Ukraine, high-quality ingots for the needs of the medical industry were smelted. The castings are used for the manufacture of light and ultra-strong endoprostheses and implants, which are chemically neutral and biologically and biomechanically compatible with the human body and do not cause rejection.

3DDA: A Novel Python Toolkit to Analyze 3D‐Dynamic Contact Angles from Molecular Dynamics Simulations

Obtaining fast and reliable contact angles in molecular dynamics simulations is crucial for screening surface wettability. Traditional methods rely on bidimensional density profile analysis to localize the liquid/vapor interface, which may not be optimal at the nanoscale, especially for nonsymmetrical droplets. Herein, 3DDA, a Python‐based code that uses the 3D droplet geometry to determine contact angles and analyze dynamic changes during spreading processes at the nanoscale, is presented. The 3D density profile of liquid molecules is enveloped using the Euclidean 3D convex hull algorithm to locate the contact line at the solid‐, liquid‐, and vapor‐phase boundaries. By fitting a general ellipsoidal function and optimizing it with the limited‐memory Broyden–Fletcher–Goldfarb–Shanno method, the best candidate function is analytically obtained, describing the interface. The angle derived from the ellipsoidal function and the solid boundary is used to gather a collection of contant angles, which are then fed into a kernel density estimator to determine the most probable angle along the contact line during the spreading process. This methodology is tested on systems such as liquid water and metals, demonstrating its efficacy and reliability. Herein, valuable insights are provided into the behavior of liquids, considering droplet asphericity induced by liquid/solid interactions.

Ultrathin α-Bi2O3 Thin-Film Transistor for Cost-Effective Oxide-TFT Inverters.

Electronics is advancing toward greater diversity and sustainability by prioritizing energy efficiency and cost-effectiveness. Metal oxide thin-film transistor (TFT) represents a technology at the forefront of advancing next-generation sustainable electronics, and exploring oxide channel compositions is a crucial step in opening opportunities for developing next-generation device applications. This study presents the first development of n-channel α-Bi2O3-TFTs using a 4 nm ultrathin channel prepared by a cost-effective vacuum-free and solvent-free liquid metal printing method in ambient air. Even the pristine device exhibited a clear TFT action but required a large negative gate bias to turn off due mainly to excess carriers from oxygen vacancy in the α-Bi2O3 channel. Oxygen-containing post-annealing reduced both channel carrier and subgap defect densities, enabling the development of depletion and enhancement-type α-Bi2O3-TFTs with the saturation mobility of 2-4 cm2 V-1 s-1. Two types of oxide-TFT-based inverter circuits, zero-VGS-NMOS and CMOS inverters, were fabricated by using α-Bi2O3-TFTs, operating in a high voltage gain of over 130. This work demonstrates the potential of oxide semiconductor materials toward the development of next-generation sustainable electronics.

Risk assessment for Na-Zn liquid metal batteries

Background Na-Zn liquid metal batteries, which operate at 600 °C, have recently been proposed as inexpensive stationary energy storage devices. As with any other electrochemical cell, their fabrication and operation involves certain risks, which need to be well understood in order to be minimised. Methods A risk assessment according to ISO 12100 is performed at the cell level for operating Na-Zn cells in the laboratory environment. Hazard identification and risk evaluation are systematically addressed, including a thorough literature review, theoretical calculations and selected experiments. Results Cell overpressure is found to be one of the main risks – and might be caused either by mistakes in battery production (humidity) or operation (over-charge/discharge). In terms of cell housing, the weakest component is clearly the feedthrough. Its failure might lead to the release of hazardous aerosols to the environment. In this context, the candidate electrolyte components LiCl and BaCl2 are especially dangerous, and should therefore be reduced or avoided if possible. Conclusions Overall, Na-Zn cells are expected to reach a very high safety level, similar to state-of-the-art ZEBRA technology, as they are not prone to thermal runaway. However, considering the still low TRL level and open questions concerning the durability of certain parts of their housing, the batteries should preferably be operated under a fume hood.

A Metalgel with Liquid Metal Continuum Immobilized in Polymer Network.

Gels are formed by fluids that expand throughout the whole volume of 3D polymer networks. To unlock unprecedented properties, exploring new fluids immobilized in polymer networks is crucial. Here, a new liquid metal-polymer gel material termed "metalgel" is introduced via fluid replacement strategy, featuring 92.40%vol liquid metal fluid as a continuum immobilized by interconnected nanoscale polymer network. The unique structure endows metalgel with high electrical conductivity (up to 3.18×106 S·m‒1), tissue-like softness (Young's modulus as low as 70kPa), and low gas permeability (4.50×10‒22m2·s‒1·Pa‒1). Besides, metalgel demonstrates electrical stability under extreme deformations, such as being run over by a 4.5-metric-tonne truck, and maintains its integrity in various environments for up to 180 days. The immobilization of high-volume-fraction liquid metal fluid is realized by electrostatic interactions is further revealed. Potential applications for metalgel are diverse and include soft electromagnetic shielding, hermetic sealing, and stimulating/sensing electrodes in implantable bioelectronics, underscoring its broad applicability.