Liquid Metal Research Articles

The biocompatibility of gallium-based liquid metals with blood and serum

The biocompatibility of gallium-based liquid metals with blood and serum

Hybrid numerical 3D model of electromagnetic levitation of molten metal

This paper introduces a new and efficient methodology for the numerical modeling of electromagnetic levitation. The model requires transferring the time-varying geometry of the molten metal from the hydrodynamic submodel to the electromagnetic submodel. The developed methodology combines a geometry transfer of the conductivity distribution of the metal/air system, and the accompanying conditional reconstruction of the electromagnetic submodel. The proposed solution strategy enables a computationally efficient simulation of the coupled process accounting for any evolution of the molten metal geometry. The developed methodology can be generalized to any magnetohydrodynamic process with the presence of a free surface of liquid metal. The method was applied to the 3D modeling of a classic example of low-scale levitation melting of aluminum.

Development of a liquid metal subchannel code applied to ocean conditions and study on the effect of core geometry parameters and ocean motions on flow and heat transfer characteristics

The Generation IV International Forum (GIF) proposes a type of liquid metal reactor, due to its thermal properties and efficient heat transfer in a relatively small system. This special heat transfer characteristic allows the liquid metal reactor to be modular in design and flexible in installation on a nuclear-powered ship. Accurate prediction of the coolant temperature and flow distribution between subchannels is important to ensure nuclear safety in the complex ocean environment. In this study, an ocean version of subchannel code is developed by adding the motion terms in the momentum equations for the liquid metal reactor core based on the previously land-based subchannel code. Since the research on the characteristics of flow resistance and heat transfer mechanism under ocean conditions is not mature, the original empirical model is still used in the ocean version code. The constitutive models of the liquid metal are analyzed and incorporated into the ocean code. The code has been verified and validated by comparing with Computational Fluid Dynamics (CFD) simulation results, and experimental data. The effect of geometric parameters such as rod Pitch to Diameter ratio (P/D), Rod to Wall gap (RTW) is studied in the liquid metal lead 7 rod bundles. In addition, the effect of heaving start-up and shutdown motions between liquid metal lead and water is discussed in the 5 × 5 bare rod bundles. In general, the modified subchannel analysis code can well complete the calculation of liquid metal reactor under ocean conditions, as well as provide support for the design and safety analysis of a liquid metal cooled fast reactor.

Flexible and Large‐Scale Liquid Metal Frequency‐Selective Surfaces: Enhanced Tuning through Mechanical Reconfiguration

The tuning capability is crucial for broadening the application possibilities of frequency‐selective surfaces (FSSs). Flexible and stretchable FSSs have attracted widespread research interest due to their ability for adhering to curved surfaces conformally and reconfiguring electromagnetic (EM) wave transmission performance mechanically. However, conventional metal FSSs lack sufficient flexibility and deformability due to material constraints, resulting in diminished durability and limited EM tuning range. In this article, a design approach for flexible liquid metal FSS (LMFSS), which can conform to curved structures and achieve a wide range of EM wave tuning via mechanical stretching without structural damage, is presented. The fabrication of LMFSS is simplified using silicone elastomer curing and liquid metal inkjet printing, avoiding the complexities of traditional microchannel techniques. In the experimental results, it is demonstrated that the designed LMFSS achieves a tuning range of up to 16% under biaxial stretch strains not more than 25%. The tuning mechanism is explored through mechanical–EM simulations and equivalent circuit analyses. Additionally, the tuning phenomenon observed in another flexible LMFSS in this study underscores the portability of the design approach and tuning mechanism. In this research, a promising direction for tunable flexible LMFSS applications is offered.

Liquid metal embrittlement and fracture behavior of three Mo metals in liquid lead-bismuth eutectic

In this work, liquid metal embrittlement (LME) and the related fracture behavior of Mo, TZM and Mo-14Re were assessed in oxygen-saturated and -depleted LBE at 350°C by means of slow strain rate tensile (SSRT) tests. Neither tensile mechanical property data nor fractographic micrographs show strong evidence of LME. Nevertheless, the observation of deep secondary cracking at the fiber-like grain boundaries of Mo and Mo-14Re tested in LBE suggests occurrence of grain boundary wetting (GBW). Moreover, oxidation-assisted crack initiation and propagation were also identified. Both fracture modes may be a concern when Mo metals with a fiber-like grain structure are used in high-oxygen LBE environment.

Nucleobase‐Driven Wearable Ionogel Electronics for Long‐Term Human Motion Detection and Electrophysiological Signal Monitoring

AbstractIonogels are considered as ideal candidates for constructing flexible electronics due to their superior electrical conductivity, flexibility, high thermal and electrochemical stability. However, it remains a great challenge to simultaneously achieve high sensitivity, repeated adhesion, good self‐healing, and biocompatibility through a straightforward strategy. Herein, inspired by nucleobase‐tackified strategy, a multifunctional adhesive ionogel is developed through one‐step radical polymerization of acrylated adenine/uracil (Aa/Ua) and acrylic acid (AA) monomers in sodium caseinate (SC) stabilized liquid metal dispersions. As a soft conductive filler, the incorporating of liquid metal not only improves the electrical conductivity, but also enhances the mechanical strength, satisfying the stretchable sensing application. The large amount of noncovalent interactions (hydrogen bonding, metal coordination, and ion‐dipole interactions) within the networks enable the ionogels to possess excellent stretchability, skin‐like softness, good self‐healing, and strong adhesion. Based on these desirable characteristics, the ionogel is suitable for wearable strain sensors to precisely detect diverse human movements under extreme environments. Moreover, the seamless adhesion with human skin allows the ionogel to function as bioelectrode patch for long‐term and high‐quality electrophysiological signal acquisition. This research provides a promising strategy for designing ionogels with tailored functionalities for wearable electronics that satisfy diverse application requirements.

Development of a New Thermal-Hydraulic Module for FRENETIC, a Code for the Multiphysics Analysis of Liquid Metal–Cooled Reactors

This paper describes the development of a new thermal-hydraulic (TH) module for the Fast REactor NEutronics/Thermal-hydraulICs (FRENETIC) multiphysics code for the full-core simulation of liquid metal–cooled fast reactors, developed at Politecnico di Torino. The code performs steady-state and transient neutronic (NE) and TH coupled calculations while maintaining a relatively low computational cost thanks to the adoption of simplified physical models. The NE module implements the nodal formulation of the multigroup neutron diffusion equations with delayed neutron precursors whereas the TH module treats the reactor hexagonal assemblies as separate channels, which are individually modeled as one-dimensional in the axial direction, accounting for the thermal coupling in the horizontal direction. The new TH module is more robust and portable while providing improved performance with respect to the previous implementation—also thanks to the adopted OpenMP parallelization. Some physical aspects that were previously neglected, such as the thermal inertia of nonfuel rods, have also been included in the model. The development was carried out in accordance with current best practices for code design, implementation, and testing, thus rendering the code easier to be maintained and possibly to be extended in the future. The code usability has also been improved by means of a set of Python classes purposely developed to simplify the input generation and postprocessing phases. This can potentially widen the usage of FRENETIC within the fast reactor community for the simulation of full-core coupled NE-TH transients and/or as a platform to test new solution methods. The paper also includes the application of this new FRENETIC version to a representative configuration of the Advanced Lead-cooled Fast Reactor European Demonstrator (ALFRED) core design. First, the nominal operating conditions of the ALFRED reactor were simulated, proving that the new upgrade of the code is faster and more robust with respect to the previous one. Then, two accidental transients where NE-TH feedback effects are relevant—an unprotected loss of flow and a total instantaneous blockage of a single fuel assembly—were considered.

Ultrathin Ga2O3 Photodetector with Fast Response and Trajectory Tracking Capability Fabricated by Liquid Metal Oxidation.

Low-dimensional Ga2O3 demonstrates a unique ultraviolet photoresponse and could be used in various electronic and optical systems. However, the low-dimensional Ga2O3 photodetector is faced with the challenges of a complex preparation process and poor device performance. In this work, ultrathin Ga2O3 layers with ∼7 nm thickness are prepared on quartz rods by UV exposure to liquid gallium. Benefiting from low-density oxygen vacancy defects cured by UV exposure, the low-dimensional Ga2O3 photodetector exhibits a high response speed (rise: 64.7 μs; fall: 51.4 μs) and an exceptional linear dynamic range of 120 dB. Furthermore, the photodetector array based on these ultrathin Ga2O3 shows an effective trajectory tracking capability by monitoring UV source motion. This work develops a simple preparation method to construct a low-dimensional UV photodetector array with fast response and useful trajectory tracking capability, exhibiting the significance of ultrathin Ga2O3 in UV optoelectronics.

STRUCTURE FORMATION OF Ni−P ALLOY ELECTROCOATINGS WITH INCREASED CORROSION RESISTANCE

Purpose of research. The main factors that reduce the protective properties of electrocrystallized coatings are the formation of volumetric defects − pores, as well as the occurrence of microgalvanic couples at grain boundaries, that is, on surface defects of the crystalline structure. Creating a non-porous structure in electrocoatings, eliminating the formation of surface defects in metal/alloy layers, as well as the possibility of replacing chromium coatings, which are obtained from toxic electrolytes, are urgent tasks. Materials and methodology. In the work, it was proposed to use electrocoatings with Ni−P alloy as protective layers on products that increase corrosion resistance. An X-ray determination of the phase composition of Ni−P electrochemical deposits was carried out. The surface morphology and corrosion resistance of coatings were studied. Results. Samples of electrochemical coatings of pure nickel and nickel-phosphorus alloy were studied. It has been established that during the formation of nickel coatings with the addition of phosphorus ions, the surface morphology has practically no pores, amorphization of deposits occurs, due to which the protective properties, namely, corrosion resistance, are improved. Scientific novelty. Factors have been identified that influence the increase in corrosion resistance of coatings − the absence of a porous structure and the formation of an amorphous state. Conclusions. The influence on the structure and properties of electrochemical coatings of a nickel-phosphorus alloy has been studied. It has been established that the addition of phosphorus ions to the nickel plating electrolyte leads to the formation of an amorphous structure in the coatings, and layers of the Ni−P alloy appear practically without the presence of pores. It has been established that the effect of increasing the corrosion resistance of the electrochemical coating with a nickel-phosphorus alloy (by 30 %) is due to the formation of an amorphous structure of the solidifying metal liquid while preventing the crystallization process during electrochemical deposition.

Numerical investigation of arc characteristics and metal properties in ELAMF-assisted WAAM with wire retraction

In this study, a multi-physics integrated model of wire arc additive manufacturing (WAAM) with wire retraction and external longitudinal alternating magnetic field (ELAMF) assistance is proposed and validated, and the effect of ELAMF on the arc plasma characteristics and metal properties are systematically and quantitatively investigated. The model comprehensively takes the arc plasma heating, wire dynamic retraction, droplet transfer, the formation and diffusion of metal vapor, the melting and solidification of molten metal, and the stirring effect of ELAMF into account. The simulated results show that ELAMF has compressed the arc morphology, and decreased the temperature, potential, current density and static pressure, which are most pronounced when the wire is at an elevated position and the transient current is at its peak phase. Meanwhile, the formation of low-temperature and low-velocity cavities in the center of arc column are promoted by ELAMF, consequently diminishing the energy transferred from the arc plasma to molten pool through thermal conduction and mitigating the squeezing of the arc plasma on the surface of molten pool. The results also demonstrate that the ELAMF has reduced the temperature gradient of liquid metal inside the molten pool, and intensified the forced convection for the occurrence of multiple circulations.

Liquid Metal Fiber-Based High-Sensitivity Strain and Pressure Sensors Enhanced by Porous Structure

Liquid Metal Fiber-Based High-Sensitivity Strain and Pressure Sensors Enhanced by Porous Structure

Technology and quality of the consumable electrodes, received by semi-continuous casting, for vacuum-arc remelting

he process of vacuum arc melt down is greatly dependent on the quality of the electrodes used. Electrodes of highly alloyed steels are negatively affected by the great amount of films, inversions, subcortical bladders and others; they are being cleansed and sanded down, this leads to substantial waste of expensive metals. For this purpose in the process of casting of highly alloyed steels a great deal of importance is put upon the creation of a method, which could be used for the purpose of protecting the metal from secondary oxidization. The increase in quality of semi-continuous cast electrodes and the removal of previously mentioned defects can be achieved with the use of slag mixtures, which posses thermo-insulating properties and can be partially melted down by the heat which is produced by the liquid metal, that fills the catalyzer. The goal of this project was to research the influence of thermal-insulating slag-producing mixtures on the quality of semi-continuous cast electrodes in the process of vacuum arc melt down in comparison to the ones that were casted under the exothermic mixtures, their effect on the process of melting and the quality of vacuum arc melt down ingots. In this project there were researched such topics as the componential, chemical composition, the physical properties of the thermo insulating mixture and the physical-chemical properties of the melt of said mixture. We researched the quality of the surface of the electrodes, the macrostructure, the chemical uniformity, density, content and the dispersal of non-metallic and gas-like additions on the transverse templates after the main cutting of 600mm, the stability of flow of the vacuum melt down, the quality of the vacuum arc melt down ingots and the rolled sheets made from the arc welded ingots. The geometry of the electrodes, casted under the thermal insulating mixture, is in order with the requirements: the degree of distortion of the profile, in comparison with the one achieved with the use of exothermic mixture, was reduced in half. The macrostructure of the electrodes is dense, without any visual defects. The losses of the metal in the process of sanding during the preparation for the vacuum arc melting were reduced by 2 times in comparison with the casting under exothermic mixture. The depth of the shrinkage cavity is reduced approximately by 12%, the form of the cavity takes the form of a “cup”. The amount of non-metallic and gas-like additions is being significantly reduced. The amount of electrodes that are being recast without issues (the creation of slag, ionization, ionization with slag), during the transition from exothermal to thermal insulating on average is reduced by 3–3,5 times. The purity of metal of vacuum arc melt down electrodes, that are casted under thermo insulating mixture, is in accordance with the requirements; the mechanical properties of rolled vacuum arc ingots exceed the norms of technical conditions.

Mechanochemistry-mediated colloidal liquid metals for electronic device cooling at kilowatt levels.

Electronic systems and devices operating at significant power levels demand sophisticated solutions for heat dissipation. Although materials with high thermal conductivity hold promise for exceptional thermal transport across nano- and microscale interfaces under ideal conditions, their performance often falls short by several orders of magnitude in the complex thermal interfaces typical of real-world applications. This study introduces mechanochemistry-mediated colloidal liquid metals composed of Galinstan and aluminium nitride to bridge the practice-theory disparity. These colloids demonstrate thermal resistances of between 0.42 and 0.86 mm2 K W-1 within actual thermal interfaces, outperforming leading thermal conductors by over an order of magnitude. This superior performance is attributed to the gradient heterointerface with efficient thermal transport across liquid-solid interfaces and the notable colloidal thixotropy. In practical devices, experimental results demonstrate their capacity to extract 2,760 W of heat from a 16 cm2 thermal source when coupled with microchannel cooling, and can facilitate a 65% reduction in pump electricity consumption. This advancement in thermal interface technology offers a promising solution for efficient and sustainable cooling of devices operating at kilowatt levels.

A Na-Li dual cation liquid metal battery with high electrode utilization and high cycling stability

Liquid metal batteries (LMBs) with Na anode exhibit the advantages of low-cost, high-safety, long-lifespan, and easy scale-up, making them promising for large-scale energy storage applications. However, the high solubility of Na and its sluggish kinetics in discharge products result in severe self-discharge and low cathode utilization, significantly hindering the development of Na-based LMBs. In this study, a stable Na-Li dual cation LMB with metal Sb cathode is designed based on the in-situ displacement reaction between Na and molten salts of lithium halides electrolyte. This design effectively suppresses the self-discharge of the battery, and the multistage discharge mechanism of the dual-cation system enhances cathode utilization. Moreover, the self-healing property of the Sb cathode protects the electrode against volume expansion and degradation, enhancing cycling performance. The Na-Li| LiCl-KCl-NaCl |Sb cell was constructed and operated at 485 °C. The battery retained 97.02 % of its capacity after 800 cycles at 0.6 C, with a decay rate of 0.00373 % per cycle. Furthermore, the battery achieves a cathode material utilization of 89 % at 0.6 C. These improvements effectively promote the development and application of LMBs.

Enhancing capacity utilization of Li|LiCl-KCl-CsCl|Bi (300 °C) liquid metal batteries through the application of external magnetic fields

Long-cycle-life, high-safety liquid metal batteries (LMBs) are considered competitive alternatives for large-scale energy storage applications. LMBs typically operate at high temperatures, and reducing their operating temperature has been a focus of research. In this study, we adopt a multi-cation molten salt LiCl-KCl-CsCl as the electrolyte for LMBs and achieve the stable operation of Li|LiCl-KCl-CsCl|Bi battery at 300 °C for the first time. However, the lower operating temperature significantly deteriorates the kinetic performance, resulting in a capacity utilization of only about 30 %. To address this issue, we apply a certain intensity of magnetic field to the battery using Helmholtz coils, which increases the capacity utilization to 100 %. This study combines the strategy of low-temperature LMBs with external magnetic field regulation, not only achieving a low operating temperature but also ensuring complete capacity release. Furthermore, this approach paves the way for the potential use of permanent magnets within battery modules to provide the magnetic field environment, without the risk of demagnetization.

Superconductivity and Mott Physics in Organic Charge Transfer Materials.

The phase diagrams of quasi two-dimensional organic superconductors display a plethora of fundamental phenomena associated with strong electron correlations, such as unconventional superconductivity, metal-insulator transitions, frustrated magnetism and spin liquid behavior. We analyze a minimal model for these compounds, the Hubbard model on an anisotropic triangular lattice, using cutting-edge quantum embedding methods respecting the lattice symmetry. We demonstrate the existence of unconventional superconductivity by directly entering the symmetry-broken phase. We show that the crossover from the Fermi liquid metal to the Mott insulator is associated with the formation of a pseudogap. The predicted momentum-selective destruction of the Fermi surface into hot and cold regions provides motivation for further spectroscopic studies. Our theoretical results agree with experimental phase diagrams of κ-BEDT organics.

Integrated simulation method and experimental validation for the vacuum induction melting process

In Vacuum Induction Melting (VIM), reduction of defects such as porosity and cracking is critical to improve electrode integrity. Traditional simulation method ignores the temperature drop of liquid metal as it passes through the tundish, leading to inaccuracies in predicting the solidification process in the mold. Additionally, the crack of ingot may occur during demolding process, which is always overlooked. This paper presents an integrated simulation method that includes the flow model of liquid metal in the tundish, as well as the solidification model and the stress model of ingot in the mold. Based on these models, the criterion for demolding time is established based on First and Fourth Strength Theories. The entire VIM process from pouring to demolding can be analyzed comprehensively through this simulation method. The method is validated by 500 kg Inconel 718 VIM trial including the temperature measurement of outer mold wall, the height measurement of liquid metal in the tundish and longitudinal sectioned experiment of ingot. The suitable criteria for porosity of 500 kg Inconel 718 ingot, including shrinkage porosity and shrinkage cavity, have been found to be the Niyama criterion threshold of 15 K0.5s0.5cm−1 and Classical porosity model. Finally, the impact of each process parameter on porosity and demolding time is studied through this method for 500 kg Inconel 718 ingot. This method is not only applied to 500 kg ingot but also to larger ingot, thereby providing a basis for the VIM process optimization.

Deterministic Fabrication of Liquid Metal Nanopatterns for Nanophotonics Applications

AbstractGallium‐based liquid metals (LMs) are widely used for stretchable and reconfigurable electronics thanks to their fluidic nature and excellent conductivity. These LMs possess attractive optical properties for photonics applications as well. However, due to the high surface tension of the LMs, it is challenging to form LM nanostructures with arbitrary shapes using conventional nanofabrication techniques. As a result, LM‐based nanophotonics has not been extensively explored. Here, a simple yet effective technique is demonstrated to deterministically fabricate LM nanopatterns with high yield over a large area. This technique demonstrates for the first time the capability to fabricate LM nanophotonic structures of various precisely defined shapes and sizes using two different LMs, that is, liquid gallium and liquid eutectic gallium–indium alloy. High‐density arrays of LM nanopatterns with critical feature sizes down to ≈100 nm and inter‐pattern spacings down to ≈100 nm are achieved, corresponding to the highest resolution of any LM fabrication technique developed to date. Additionally, the LM nanopatterns demonstrate excellent long‐term stability under ambient conditions. This work paves the way toward further development of a wide range of LM nanophotonics technologies and applications.

Cellulose nanofibers/liquid metal hydrogels with high tensile strength, environmental adaptability and electromagnetic shielding for temperature monitoring and strain sensors

Hydrogel sensors are widely recognized in the fields of flexible electronics and human motion monitoring due to their multiple properties and potential applications. However, how to prepare hydrogels with multiple excellent properties simultaneously and how to improve the compatibility of conductive fillers with hydrogel matrices remain a major challenge. Therefore, in this work, liquid metal (LM) droplets stabilized by cellulose nanofibers (CNFs) were utilized to initiate the polymerization of acrylamide monomer (Am), which was used as a conductive filler. Meanwhile, reduced graphene oxide (rGO) was introduced to bridge the LM droplets. The hydrogels were then further crosslinked in glycerol. The constructed CNF@LM/polyacrylamide/rGO/gelatin/glycerol hydrogel possesses high tensile properties (>1317 %), high environmental adaptability (−80 to 80 °C), and adhesion properties for multifunctional sensing. What's more, it offers the high sensitivity of both a strain sensor and a temperature sensor for accurate monitoring of human movement at room temperature and even in extreme environments. In addition, this hydrogel has excellent electromagnetic shielding properties and antimicrobial properties. This research opens up a new direction for the preparation of multifunctional hydrogel sensors, expanding their applications in cutting-edge fields such as temperature monitoring, wearable smart devices, e-skin and intelligent robotics.

Mean-field homogenization of liquid metal elastomer composites: comparative study and exact dilute solution of core–shell inclusion

Liquid metal-elastomer composites (LMECs) have gathered significant attention for their potential applications in various functional stretchable devices, with inclusion sizes ranging from micrometers to nanometers. These composites exhibit exceptional properties, such as high electric permittivity and thermal conductivity, surpassing those of the elastomer matrix, thus enabling a broader range of applications without compromising the material's stretchability. To investigate the diverse effective elastic and functional properties of LMECs, micromechanics-based homogenization method based on Eshelby's inclusion solution are invaluable. However, the extreme contrast in elastic constants among the phases in LMECs, particularly for nanosized inclusions where a considerable amount of stiff metal oxide forms around the inclusions, can lead to critical failure in predicting effective properties if inadequate homogenization approach is employed. In this study, we present multiple mean-field homogenization approaches applicable to LMECs with core-shell morphology, namely: (i) multi-phase, (ii) sequential, (iii) pseudo-grain, and (iv) direct approaches. We compare the accuracy of the models concerning effective elastic, thermal, and dielectric properties, evaluated against numerical homogenization results and compared with reported experimental data. Specifically, we highlight homogenization scheme utilizing exact field solutions of dilute core-shell inclusion, emphasizing the importance of accurately capturing the field in the micromechanics of LMECs. Furthermore, we demonstrate that widely utilized interphase model could not properly resolve the core-shell morphology and thus should be avoided. This comprehensive assessment provides critical insights into the proper homogenization strategies for designing advanced LMECs with precise prediction of effective properties.