Forces in Liquid Metal Contacts

2014 ◽  
Author(s):  
Lars Duggen ◽  
Stefan Mátéfi-Tempfli
Keyword(s):  
Liquid Metal ◽  
Liquid Metals ◽  
Tensile Force ◽  
Liquid Gallium ◽  
Metal Contacts ◽  
Circular Symmetry ◽  
Capillary Bridges

Using rather well known theory about capillary bridges between two electrodes we calculate the tensile force that can be applied to liquid metal contacts in the micrometer regime. Assuming circular symmetry, full wetting of the electrodes, and neglecting gravity, we present a brief review of the necessary theory and find numerically the forces to be in the 100μN range for liquid metals as mercury and liquid Gallium suspended between electrodes of 20μm radius.

scholarly journals Insights into fluidic endogenous magnetism and magnetic monopoles from a liquid metal droplet machine

Soft Science ◽  
2021 ◽  
Author(s):  
Ying-Xin Zhou ◽  
Jia-Sheng Zu ◽  
Jing Liu
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Magnetic Particles ◽  
Magnetic Monopole ◽  
Liquid Metals ◽  
Magnetic Monopoles ◽  
Theoretical Interpretation ◽  
Liquid Gallium ◽  
Dynamic Adjustment ◽  
Metal Machine

Magnetism and magnetic monopoles are among the most classical issues in physics. Conventional magnets are generally composed of rigid materials and may face challenges in extreme situations. Here, as an alternative to rigid magnets, we propose, for the first time, the generation of fluidic endogenous magnetism and construct a magnetic monopole through tuning with a liquid metal machine. Based on theoretical interpretation and conceptual experimental observations, we illustrate that when liquid metals, such as gallium alloy, in a solution rotate under electrical actuation, they form an endogenous magnetic field inside. This explains the phenomenon where two such discrete metal droplets can easily fuse together, indicating their reciprocal attraction via the N and S poles. Furthermore, we reveal that a self-fueled liquid metal motor also runs as an endogenous fluidic magnet owing to the electromagnetic homology. When aluminum is added to liquid gallium in solution, it forms a spin motor and dynamically variable charge distribution that produces endogenous magnetism inside. This explains the common phenomena where reflective collision and attractive fusion between running liquid metal motors occur, which are partially caused by the dynamic adjustment of their N and S polarities, respectively. On this basis, more experimental approaches capable of generating dynamic electrical fields also work for the same target. Finally, we propose that such a fluidic endogenous magnet could lead to a magnetic monopole and four technical routes to realize this are suggested. The first involves matching the interior flow of liquid metal machines. The second is the superposition between an external electric effect and the magnetic field. The third route involves composite construction between magnetic particles and a liquid metal spin motor. Finally, chemical methods, such as via galvanic cell reactions, are proposed. Overall, the present theory and identified experimental evidence illustrate the role of a liquid metal machine as a fluidic endogenous magnet and highlight promising methods for the realization of magnetic monopoles. A group of unconventional magnetoelectric devices and applications could therefore be possible in the near future.

scholarly journals A general approach to composites containing nonmetallic fillers and liquid gallium

2021 ◽  
Vol 7 (1) ◽  
pp. eabe3767
Author(s):  
Chunhui Wang ◽  
Yan Gong ◽  
Benjamin V. Cunning ◽  
Seunghwan Lee ◽  
Quan Le ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Electromagnetic Interference ◽  
Volume Fraction ◽  
Liquid Metals ◽  
Liquid Gallium ◽  
Shielding Effectiveness ◽  
Metallic Particles ◽  
Thermal Paste ◽  
Fit For Purpose ◽  
Electromagnetic Interference Shielding Effectiveness

We report a versatile method to make liquid metal composites by vigorously mixing gallium (Ga) with non-metallic particles of graphene oxide (G-O), graphite, diamond, and silicon carbide that display either paste or putty-like behavior depending on the volume fraction. Unlike Ga, the putty-like mixtures can be kneaded and rolled on any surface without leaving residue. By changing temperature, these materials can be stiffened, softened, and, for the G-O–containing composite, even made porous. The gallium putty (GalP) containing reduced G-O (rG-O) has excellent electromagnetic interference shielding effectiveness. GalP with diamond filler has excellent thermal conductivity and heat transfer superior to a commercial liquid metal–based thermal paste. Composites can also be formed from eutectic alloys of Ga including Ga-In (EGaIn), Ga-Sn (EGaSn), and Ga-In-Sn (EGaInSn or Galinstan). The versatility of our approach allows a variety of fillers to be incorporated in liquid metals, potentially allowing filler-specific “fit for purpose” materials.

Rotating thermal convection in liquid gallium: multi-modal flow, absent steady columns

2018 ◽  
Vol 846 ◽  
pp. 846-876 ◽  
Author(s):  
Jonathan M. Aurnou ◽  
Vincent Bertin ◽  
Alexander M. Grannan ◽  
Susanne Horn ◽  
Tobias Vogt
Keyword(s):  
Liquid Metal ◽  
Thermal Convection ◽  
Convective Flow ◽  
Laboratory Experiments ◽  
Liquid Metals ◽  
Low Frequency ◽  
Working Fluid ◽  
Liquid Gallium ◽  
Thermally Driven ◽  
Convective Motions

Earth’s magnetic field is generated by convective motions in its liquid metal core. In this fluid, the heat diffuses significantly more than momentum, and thus the Prandtl number$Pr$is well below unity. The thermally driven convective flow dynamics of liquid metals are very different from moderate-$Pr$fluids, such as water and those used in current dynamo simulations. In order to characterise rapidly rotating thermal convection in low-$Pr$number fluids, we have performed laboratory experiments in a cylinder of aspect ratio$\unicode[STIX]{x1D6E4}=1.94$using liquid gallium ($Pr\simeq 0.025$) as the working fluid. The Ekman number varies from$E\simeq 5\times 10^{-6}$to$5\times 10^{-5}$and the Rayleigh number varies from$Ra\simeq 2\times 10^{5}$to$1.5\times 10^{7}$. Using spectral analysis stemming from point-wise temperature measurements within the fluid and measurements of the Nusselt number$Nu$, we characterise the different styles of low-$Pr$rotating convective flow. The convection threshold is first overcome in the form of container-scale inertial oscillatory modes. At stronger forcing, sidewall-attached modes are identified for the first time in liquid metal laboratory experiments. These wall modes coexist with the bulk oscillatory modes. At$Ra$well below the values where steady rotating columnar convection occurs, the bulk flow becomes turbulent. Our results imply that rotating convective flows in liquid metals do not develop in the form of quasisteady columns, as in moderate-$Pr$fluids, but in the form of oscillatory convective motions. Thus, thermally driven flows in low-$Pr$geophysical and astrophysical fluids can differ substantively from those occurring in$Pr\simeq 1$models. Furthermore, our experimental results show that relatively low-frequency wall modes are an essential dynamical component of rapidly rotating convection in liquid metals.

Liquid metal-based nanocomposite materials: Fabrication technology and applications

Nanoscale ◽  
2021 ◽  
Author(s):  
Hiroki Ota ◽  
Nyamjargal Ochirkhuyag ◽  
Ryosuke Matsuda ◽  
Zihao Song ◽  
Fumika Nakamura ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Flexible Electronics ◽  
Liquid Metals ◽  
Nanocomposite Materials ◽  
Fabrication Technology

Research on liquid metals has been steadily garnering more interest in recent times because the properties of these metals are conducive to flexible electronics applications; further, these metals are in...

scholarly journals Liquid Metals: Liquid Metal Marbles (Adv. Funct. Mater. 2/2013)

2013 ◽  
Vol 23 (2) ◽  
pp. 137-137 ◽  
Author(s):  
Vijay Sivan ◽  
Shi-Yang Tang ◽  
Anthony P. O'Mullane ◽  
Phred Petersen ◽  
Nicky Eshtiaghi ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Liquid Metals

Unusual Wetting Behavior of Liquid Metals on Porous Layer Formed at Surface of Iron Substrate Prepared by Oxidation-Reduction Process

2007 ◽  
Vol 561-565 ◽  
pp. 1699-1701
Author(s):  
Nobuyuki Takahira ◽  
Takeshi Yoshikawa ◽  
Toshihiro Tanaka
Keyword(s):  
Liquid Metal ◽  
Porous Layer ◽  
Liquid Metals ◽  
Reduction Process ◽  
Surface Oxidation ◽  
Porous Iron ◽  
Normal Contact ◽  
Wetting Behavior ◽  
Oxidation Reduction ◽  
Oxidized Iron

Unusual wetting behavior of liquid Cu was found on a surface-oxidized iron substrate in reducing atmosphere. Liquid Cu wetted and spread very widely on the iron substrate when a droplet was attached with the substrate in Ar-10%H2 after the surface oxidation of the substrate. The oxidationreduction process fabricates a porous layer at the surface of the iron substrate. The pores in the porous iron layer are 3-dimensionally interconnected. Thus, liquid metals, which are contacted with the reduced iron samples, penetrate into these pores by capillary force to cause the unusual wetting behavior. It has been already confirmed that liquid Ag, Sn, In and Bi show this phenomenon onto surface-porous iron samples as well as liquid Cu. This unusual wetting behavior of a liquid metal has been correlated to the normal contact angle of the liquid metal on a flat iron substrate.

Suitability of Eutectic Field’s Metal for Use in an Electromagnetohydrodynamically-Enhanced Experimental Two-Phase Flow Loop

2012 ◽  
Author(s):  
A. Lipchitz ◽  
Lilian Laurent ◽  
G. D. Harvel
Keyword(s):  
Liquid Metal ◽  
Two Phase Flow ◽  
Nuclear Reactors ◽  
Liquid Metals ◽  
Metal Flow ◽  
Phase Flow ◽  
Laboratory Setting ◽  
Flow Loop ◽  
Fast Reactors ◽  
Two Phase

Several Generation IV nuclear reactors, such as sodium fast reactors and lead-bismuth fast reactors, use liquid metal as a coolant. In order to better understand and improve the thermal hydraulics of liquid metal cooled GEN IV nuclear reactors liquid metal flow needs to be studied in experimental circulation loops. Experimental circulation loops are often located in a laboratory setting. However, studying liquid metal two phase flow in laboratory settings can be difficult due to the high temperatures and safety hazards involved with traditional liquid metals such as sodium and lead-bismuth. One solution is to use a low melt metal alloy that is as benign as reasonably achievable. Field’s metal is a eutectic alloy of 51% Indium, 32.5% Bismuth and 16.5% Tin by weight and has a melting point of 335K making it ideal for use in a laboratory setting. A study is undertaken to determine its suitability to use in a two-phase experimental flow loop enhanced by magnetohydrodynamic forces. The study investigated its reactivity with air and water, its ability to be influenced by magnetic fields, its ability to flow, and its ease of manufacture. The experiments melted reference samples of Field’s metal and observed its behaviour in a glass beaker, submerged in water and an inclined stainless steel pipe. Then Field’s metal was manufactured in the laboratory and compared to the sample using the same set of experiments and standards. To determine Field’s metal degree of magnetism permanent neodymium magnets were used. Their strength was determined using a Gaussmeter. All experiments were recorded using a COHU digital camera. Image analysis was then performed on the video to determine any movements initiated by the magnetic field forces. In conclusion, Field’s metal is more than suitable for use in experimental settings as it is non-reactive, non-toxic, simple to manufacture, easy to use, and responds to a magnetic force.

Convective Cooling of Compact Electronic Devices via Liquid Metals with Low Melting Points

2021 ◽  
Author(s):  
Guilin Liu ◽  
Jing Liu
Keyword(s):  
Heat Transfer ◽  
Melting Point ◽  
Liquid Metal ◽  
High Performance ◽  
Flow Resistance ◽  
Heat Dissipation ◽  
Liquid Metals ◽  
Electronic Devices ◽  
Convective Cooling ◽  
Heat Exchanger Design

Abstract The increasingly high power density of today's electronic devices requires the cooling techniques to produce highly effective heat dissipation performance with as little sacrifice as possible to the system compactness. Among the currently available thermal management schemes, the convective liquid metal cooling provides considerably high performance due to their unique thermal properties. This paper firstly reviews the studies on convective cooling using low-melting-point metals published in the past few decades. A group of equations for the thermophysical properties of In-Ga-Sn eutectic alloy is then documented by rigorous literature examination, following by a section of correlations for the heat transfer and flow resistance calculation to partially facilitate the designing work at the current stage. The urgent need to investigate the heat transfer and flow resistance of forced convection of low-melting-point metals in small/mini-channels, typical in compact electronic devices, is carefully argued. Some special aspects pertaining to the practical application of this cooling technique, including the entrance effect, mixed convection, and compact liquid metal heat exchanger design, are also discussed. Finally, future challenges and prospects are outlined.

Development of High Temperature Liquid Metal Heat Transfer Fluids for CSP Applications

2014 ◽  
Author(s):  
Gopinath R. Warrier ◽  
Y. Sungtaek Ju ◽  
Jan Schroers ◽  
Mark Asta ◽  
Peter Hosemann
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Liquid Metal ◽  
Liquid Metals ◽  
Research Effort ◽  
Structural Materials ◽  
Forced Flow ◽  
Oxygen Control ◽  
Ongoing Research ◽  
Heat Transfer Fluids

In response to the DOE Sunshot Initiative to develop low-cost, high efficiency CSP systems, UCLA is leading a multi-university research effort to develop new high temperature heat transfer fluids capable of stable operation at 800°C and above. Due to their operating temperature range, desirable heat transfer properties and very low vapor pressure, liquid metals were chosen as the heat transfer fluid. An overview of the ongoing research effort is presented. Development of new liquid metal coolants begins with identification of suitable candidate metals and their alloys. Initial selection of candidate metals was based on such parameters as melting temperature, cost, toxicity, stability/reactivity Combinatorial sputtering of the down selected candidate metals is used to fabricate large compositional spaces (∼ 800), which are then characterized using high-throughput techniques (e.g., X-ray diffraction). Massively parallel optical methods are used to determine melting temperatures. Thermochemical modeling is also performed concurrently to compliment the experimental efforts and identify candidate multicomponent alloy systems that best match the targeted properties. The modeling effort makes use of available thermodynamic databases, the computational thermodynamic CALPHAD framework and molecular-dynamics simulations of molten alloys. Refinement of available thermodynamics models are performed by comparison with available experimental data. Characterizing corrosion in structural materials such as steels, when using liquid metals, and strategies to mitigate them are an integral part of this study. The corrosion mitigation strategy we have adopted is based on the formation of stable oxide layers on the structural metal surface which prevents further corrosion. As such oxygen control is crucial in such liquid metal systems. Liquid metal enhanced creep and embrittlement in commonly used structural materials are also being investigated. Experiments with oxygen control are ongoing to evaluate what structural materials can be used with liquid metals. Characterization of the heat transfer during forced flow is another key component of the study. Both experiments and modeling efforts have been initiated. Key results from experiments and modeling performed over the last year are highlighted and discussed.

Sign in / Sign up

Export Citation Format

Share Document