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Showing papers on "Liquid metal published in 2006"


Journal ArticleDOI
07 Jul 2006-Science
TL;DR: X-ray measurements reveal a crystalline monolayer at the surface of the eutectic liquid Au82Si18, at temperatures above the alloy's melting point, notable, considering that AuSi does not form stable bulk crystalline phases at any concentration and temperature.
Abstract: X-ray measurements reveal a crystalline monolayer at the surface of the eutectic liquid Au82Si18, at temperatures above the alloy's melting point. Surface-induced atomic layering, the hallmark of liquid metals, is also found below the crystalline monolayer. The layering depth, however, is threefold greater than that of all liquid metals studied to date. The crystallinity of the surface monolayer is notable, considering that AuSi does not form stable bulk crystalline phases at any concentration and temperature and that no crystalline surface phase has been detected thus far in any pure liquid metal or nondilute alloy. These results are discussed in relation to recently suggested models of amorphous alloys.

174 citations


Journal ArticleDOI
TL;DR: In this paper, a silicon-nitride rod with a hole in one end was plunged into liquid aluminum to hold a known volume of air in contact with the liquid metal at a constant temperature.
Abstract: Entrained double oxide films have been held responsible for reductions in mechanical properties in aluminum casting alloys. However, their behavior in the liquid metal, once formed, has not been studied directly. It has been proposed that the atmosphere entrapped in the double oxide film defect will continue to react with the liquid metal surrounding it, perhaps leading to its elimination as a significant defect. A silicon-nitride rod with a hole in one end was plunged into liquid aluminum to hold a known volume of air in contact with the liquid metal at a constant temperature. The change in the air volume with time was recorded by real-time X-ray radiography to determine the reaction rates of the trapped atmosphere with the liquid aluminum, creating a model for the behavior of an entrained double oxide film defect. The results from this experiment showed that first oxygen, and then nitrogen, was consumed by the aluminum alloy, to form aluminum oxide and aluminum nitride, respectively. The effect of adding different elements to the liquid aluminum and the effect of different hydrogen contents were also studied.

104 citations


Journal ArticleDOI
TL;DR: In this article, a 3D transient heat transfer and fluid flow model was used to calculate the initiation time of liquid metal expulsion during laser spot welding of 304 stainless steel, and the size range of ejected metal droplets was determined by examining the interior surface of the tube after the experiments.
Abstract: During laser spot welding of many metals and alloys, the peak temperatures on the weld pool surface are very high and often exceed the boiling points of materials. In such situations, the equilibrium pressure on the weld pool surface is higher than the atmospheric pressure and the escaping vapour exerts a large recoil force on the weld pool surface. As a consequence, the molten metal may be expelled from the weld pool surface. The liquid metal expulsion has been examined both experimentally and theoretically for the laser spot welding of 304 stainless steel. The ejected metal droplets were collected on the inner surface of an open ended quartz tube which was mounted perpendicular to the sample surface and co-axial with the laser beam. The size range of the ejected particles was determined by examining the interior surface of the tube after the experiments. The temperature distribution, free surface profile of the weld pool and the initiation time for liquid metal expulsion were computed based on a three-dimensional transient heat transfer and fluid flow model. By comparing the vapour recoil force with the surface tension force at the periphery of the liquid pool, the model predicted whether liquid metal expulsion would take place under different welding conditions. Expulsion of the weld metal was also correlated with the depression of the liquid metal in the middle of the weld pool due to the recoil force of the vapourized material. Higher laser power density and longer pulse duration significantly increased liquid metal expulsion during spot welding.

60 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated a novel method to significantly lower the chip temperature by using liquid metal with low melting point as the cooling fluid, and the results indicated that the temperature of the computer chip can be significantly reduced with the increasing flow rate of liquid gallium, which suggests that an even higher power dissipation density can be achieved with a large flow of liquid metal and large area of heat dissipation.
Abstract: With the improvement of computational speed, thermal management becomes a serious concern in computer system. CPU chips are squeezing into tighter and tighter spaces with no more room for heat to escape. Total power-dissipation levels now reside about 110 W, and peak power densities are reaching 400–500 W/mm2 and are still steadily climbing. As a result, higher performance and greater reliability are extremely tough to attain. But since the standard conduction and forced-air convection techniques no longer be able to provide adequate cooling for sophisticated electronic systems, new solutions are being looked into liquid cooling, thermoelectric cooling, heat pipes, and vapor chambers. In this paper, we investigated a novel method to significantly lower the chip temperature using liquid metal with low melting point as the cooling fluid. The liquid gallium was particularly adopted to test the feasibility of this cooling approach, due to its low melting point at 29.7 °C, high thermal conductivity and heat capacity. A series of experiments with different flow rates and heat dissipation rates were performed. The cooling capacity and reliability of the liquid metal were compared with that of the water-cooling and very attractive results were obtained. Finally, a general criterion was introduced to evaluate the cooling performance difference between the liquid metal cooling and the water-cooling. The results indicate that the temperature of the computer chip can be significantly reduced with the increasing flow rate of liquid gallium, which suggests that an even higher power dissipation density can be achieved with a large flow of liquid gallium and large area of heat dissipation. The concept discussed in this paper is expected to provide a powerful cooling strategy for the notebook PC, desktop PC and large computer. It can also be extended to more wide area involved with thermal management on high heat generation rate.

59 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of temperature and strain rate on the susceptibility of one of the most promising candidate materials for cladding and high temperature components for ADS, Ferritic/Martensitic steel (T91), to liquid metal embrittlement have been investigated in the temperature interval 150-450 °C, at strain rates between 1 x 10 -3 s -1 and 1 × 10 -6 s −1.

52 citations


Journal ArticleDOI
TL;DR: In this article, a solution to the magnetohydrodynamic (MHD) problem for the V-Li concept may be attainable using multi-layer coatings or a flow channel insert with vanadium in contact with the flowing Li instead of a ceramic insulating layer.

52 citations


Journal ArticleDOI
TL;DR: In this article, the authors evaluated the performance of jet impingement for high heat-flux cooling and showed that it is capable of accommodating a heat flux of about 20MW/m 2 over an area of 10 −4 ǫm 2.

52 citations


Journal ArticleDOI
TL;DR: In this article, the modified Stokes-Einstein formula was combined with the authors' model for the melting point viscosity to predict self-diffusivity of liquid metallic elements.
Abstract: By combining the modified Stokes-Einstein formula with the authors’ model for the melting-point viscosity, the authors present a model for accurate predictions of self-diffusivity of liquid metallic elements. The model is expressed in terms of well-known physical quantities and has been applied to various liquid metallic elements for which experimental data are available. The results of calculations show that agreement with experimental data is excellent; the uncertainties in the calculations of the self-diffusivities in various liquid metallic elements are equal to the uncertainties associated with experimental measurements. Also, the authors propose an expression for the temperature dependence of self-diffusivity in liquid metallic elements in terms of melting-point temperature. Using the model, self-diffusivity data are predicted for liquid iron, cobalt, nickel, titanium, aluminum, magnesium, silicon, and so forth.

48 citations


Journal ArticleDOI
TL;DR: In this paper, a high temperature, gamma, and neutron radiation resistant ultrasonic sensors that must operate continuously in a liquid Pb/Bi alloy up to a temperature of 450 degC was developed.
Abstract: This paper is devoted to the development of high temperature, gamma, and neutron radiation resistant ultrasonic sensors that must operate continuously in a liquid Pb/Bi alloy up to a temperature of 450 degC. The main problems are acoustic coupling of a piezoelectric element to a protector and wetting of the sensor by a heavy liquid metal. The piezoelement was attached to the sensor body by a gold to gold diffusion bonding process, monitored ultrasonically. Long-lasting wetting of the active surface of the sensors was achieved by coating the front face with a protective diamond-like carbon (DLC) layer. Due to the high radiation, only a limited number of materials could be used in the sensor design. The best performance was obtained using bismuth titanate piezoelectric elements, which showed no noticeable changes of pulse responses and transfer coefficients during irradiation and high-temperature tests. The housing of the sensors is made of stainless steel AISI 316 and is laser welded, and a high-temperature otimes 1-mm 15-m-long mineral cable is used. The ultrasonic velocity in the liquid Pb/Bi in the temperature range 160 degC-460 degC was measured using developed sensors, and the signal losses at various distances up to 0.8 m were evaluated

39 citations


Journal ArticleDOI
TL;DR: In this article, the surface tension of liquid Ni-Cu-Fe alloys has been measured over a wide temperature range, including the undercooled regime, using a noncontact technique.
Abstract: Density and surface tension of liquid Ni-Cu-Fe alloys have been measured over a wide temperature range, including the undercooled regime. A non-contact technique was used, consisting of an electrom ...

35 citations


Journal ArticleDOI
TL;DR: In this article, the current understanding of liquid metal embrittlement (LME) and the mechanism of failure in aluminium heat exchangers is reviewed. But this paper is restricted to the case of aluminum heat exchanger.

Journal ArticleDOI
TL;DR: In this article, the surface morphology of metal powders was studied on their surface morphology, and it was observed that shape of powder particles depends on apex angle, superheat of liquid metal, type of metal and particle size range within a powder collective.
Abstract: There are a number of process parameters which affect the characteristics of metal powders produced by free fall gas atomization. In the following work effects of various process parameters like apex angle of atomizer, focal length of atomizer, number of nozzles, diameter of nozzles, diameter of liquid metal delivery tube, superheat of liquid metal and type of metal etc. were studied on their surface morphology. It was observed that shape of powder particles depends on apex angle, superheat of liquid metal, type of metal and particle size range within a powder collective. Other parameters like focal length of atomizer, number of nozzles, diameter of nozzles and diameter of liquid metal delivery tube were found to have no effect on the shape of powder particles. However, Surface porosity and solidification shrinkage were observed on almost all types of metal powders.

Journal ArticleDOI
TL;DR: In this paper, a partial shrinkage model for selective laser sintering of a metal powder mixture that contains two kinds of metal powders with significantly different melting points is developed.

Journal ArticleDOI
TL;DR: In this article, the density of eutectic alloy of Pb-Li was measured in the condensed state in the temperature range from 360 to 880 K. The confidence error of the experimental results is 0.4% and 0.3% for the solid and liquid phases, respectively.
Abstract: The method of penetrating gamma-rays is used to measure the density of eutectic alloy of the Pb-Li system in the condensed state in the temperature range from 360 to 880 K. The confidence error of the experimental results is 0.4% and 0.3% for the solid and liquid phases, respectively. The experimental results for the density of lead-lithium eutectic are used to calculate the thermal expansion in the investigated temperature range. The investigation results are compared with the available literature data on the thermal properties of Pb-Li eutectic in the solid and liquid phases.

Journal ArticleDOI
TL;DR: In this article, a semi-empirical analysis of planar-flow melt spinning is presented, which provides a theoretical basis for a previously reported empirical stability window, and predicts an extension to the stability limits by adjusting the pressure outside the upstream meniscus relative to the pressure inside the downstream Meniscus.

Journal ArticleDOI
TL;DR: In this article, the authors provide qualitative and quantitative data on liquid metal free surface flow behavior under fusion relevant magnetic fields, which is a key feasibility issue for flowing liquid metal plasma facing component (PFC) systems, pertains to their magnetohydrodynamic (MHD) behavior under the spatially varying magnetic field environment.

Journal ArticleDOI
TL;DR: In this article, the transpiration method was used to investigate the equilibrium evaporation behavior of radionuclide polonium generated and accumulated in liquid lead-bismuth eutectic (LBE) coolers.
Abstract: Experimental study using the transpiration method investigates equilibrium evaporation behavior of radionuclide polonium (210Po) generated and accumulated in liquid lead-bismuth eutectic (LBE) cool...

Patent
18 May 2006
TL;DR: In this paper, a high temperature damper for a roller bearing having a long shelf life and capable of withstanding temperatures in a gas turbine engine shaft is presented, which includes a damping chamber formed between a stator housing and the outer race of the bearing, and is filled with a liquid metal such as Gallium.
Abstract: A high temperature damper for a roller bearing having a long shelf life and capable of withstanding temperatures in a gas turbine engine shaft. The damper includes a damping chamber formed between a stator housing and the outer race of the bearing, and is filled with a liquid metal such as Gallium that has a paste-like consistency at room temperature so as not to flow and leak from the damping chamber, and a liquid-like consistency at about 1,500 degrees F. in order to withstand the extreme temperatures of a gas turbine engine. Seals having a U-shape cross section are made of a high temperature metal like Hastalloy or Hynes and enclose the liquid metal within the damping chamber.

Journal ArticleDOI
TL;DR: In this article, the effect of an electric current supplied from outside on the natural convection of liquid metal under a uniform magnetic field was studied both experimentally and numerically, where two electrodes were inserted at the center of the hot and cold electroconductive sidewalls, respectively.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the viscosity of high-melting slags containing chromium oxides and found that adding chromium oxide into the slag decreases the visco-composition relation and the influence becomes weaker at high CrOx contents.
Abstract: In order to be able to understand and model the kinetics of heterogeneous reactions and transport phenomena it is necessary to have experimental data of physical properties like viscosity, surface energy and interfacial energy. In this study viscosity of high-melting slags containing chromium oxides were measured. Central results and observed relationships and modelling are described. The results showed that addition of chromium oxide into the slag decreases the viscosity but the influence becomes weaker at high CrOx contents. The viscosity–composition relation was evaluated by a modified Iida's model and a good agreement between the experimental and calculated results was observed.Interfacial phenomena between liquid metal and slag with gas bubbles entering through the metal–slag interface were investigated by X-ray transmission technique. Bubble behaviour at metal–slag interface and dispersion of metal droplets into the slag were measured as a function of interfacial tension, gas bubble size and slag viscosity. The effect of different parameters on metal entrainment is discussed.

Journal ArticleDOI
TL;DR: In this paper, an integrated model of the atomization of a liquid column perturbed by a flowing gas phase is proposed, termed Surface Wave Formation (SWF) algorithm, which is based on the concept of the formation of sinusoidal waves travelling along the surface of the liquid.

Patent
Cinotti Luciano1
19 Sep 2006
TL;DR: In this paper, a nuclear core is cooled with a liquid metal (for example, a heavy liquid metal, such as lead or lead-bismuth eutectic), of the type having a cylindrical inner vessel that divides a hot collector over a core from a substantially annular cold collector surrounding the hot collector.
Abstract: A nuclear reactor ( 1 ) is provided, in particular a nuclear reactor cooled with a liquid metal (for example, a heavy liquid metal, such as lead or lead-bismuth eutectic), of the type having a cylindrical inner vessel ( 15 ) that divides a hot collector ( 6 ) over a core ( 4 ) from a substantially annular cold collector ( 7 ) surrounding the hot collector; housed in the cold collector ( 7 ) is a plurality of integrated circulation and heat-exchange assemblies ( 20 ), each of which includes a pump ( 9 ), two heat exchangers ( 10 ) set at the sides of the pump, and a conveying structure ( 21 ) through which a primary fluid ( 8 ) for cooling the core passes from the pump to the heat exchanger, all of which are fixedly connected to one another to form a unitary structure; each integrated assembly has an inlet ( 26 ) connected to the hot collector ( 6 ) and two outlet sections ( 34 ) in the cold collector ( 7 ).

Journal ArticleDOI
Ze-Jun Xiao1, Gui-Qin Zhang1, Jianqiang Shan1, Xue-Song Bai, D Jia1 
TL;DR: In this article, the authors dealt with heat transfer with high temperature (300-700°C) and low Pe number (20∼70), and heat transfer in an annulus.

Journal ArticleDOI
TL;DR: In this paper, a series of experiments was performed to simulate the behavior of a solid particle bed in a liquid pool against pressure transients, and physical models and methods used in the code can reasonably represent the transient behaviors of pool multiphase flows with rich solid phases as observed in the experiments.
Abstract: In order to model the mobility of the postulated disrupted core in a core disruptive accident of a liquid metal faster reactor and to provide data for the verification of a reactor safety analysis code (SIMMER-III) a series of experiments was performed to simulate the behavior of a solid particle bed in a liquid pool against pressure transients. Experimental analyses using the SIMMER-III code show that physical models and methods used in the code can reasonably represent the transient behaviors of pool multiphase flows with rich solid phases as observed in the experiments. The validation of several key models of SIMMER-III was also discussed for treating transient behaviors of the solid-particle phase in multiphase flows.

Proceedings ArticleDOI
01 Jan 2006
TL;DR: In this article, a prototype bismuth propellant feed and control system was constructed and tested, and an electromagnetic pump was used to provide fine control of the hydrostatic pressure, and a new type of in-line flow sensor was developed to provide an accurate, real-time measurement of the mass flow rate.
Abstract: A prototype bismuth propellant feed and control system was constructed and tested. An electromagnetic pump was used in this system to provide fine control of the hydrostatic pressure, and a new type of in-line flow sensor was developed to provide an accurate, real-time measurement of the mass flow rate. High-temperature material compatibility was a driving design requirement for the pump and flow sensor, leading to the selection of macor for the main body of both components. Post-test inspections of both components revealed no cracks or leaking in either. In separate proof-of-concept experiments, the pump produced a linear pressure rise as a function of current that compared favorably with theoretical pump pressure predictions, with a pressure of 10 kPa at 30 A. Flow sensing was successfully demonstrated in a bench-top test using gallium as a substitute liquid metal. A real-time controller was successfully used to control the entire system, simultaneously monitoring all power supplies and performing data acquisition duties.

Journal ArticleDOI
TL;DR: In this article, a response surface model of the luminous flame emissivity of sodium pool fire has been proposed for use in safety analysis computer codes of a liquid metal fast reactor, which can be easily employed in the sodium fire analysis codes because it is a simple quadratic expression.

Journal ArticleDOI
J. Murai1, T. Marukawa1, T. Mima1, Shigeo Arai1, K. Sasaki1, Hiroyasu Saka1 
TL;DR: In this paper, it was shown that the interfacial energy between the substrates and liquid metals depends on the size of liquid metal clusters and changes significantly at around 20 µm.
Abstract: Crystalline clusters of Bi and Sn with the diameters ranging from 100 to 5 nm were prepared by in situ evaporation on to different kinds of substrates in a transmission electron microscope. These metal clusters were then heated to the molten state and behaviour of the metal liquid clusters observed in situ in the transmission electron microscope. The contact angle of liquid clusters of Bi and Sn on different kinds of substrates changes as a function of the size of liquid metal clusters. It was concluded that the interfacial energy between the substrates and liquid metals depends on the size of liquid metal clusters and changes significantly at around 20 nm.

Journal ArticleDOI
TL;DR: In this article, a mathematical model for heat transfer and fluid flow in thin films of molten metal during nanosecond pulsed laser irradiation was developed, which includes the highly nonlinear dependence of evaporative flux on local interfacial temperature and positive disjoining pressure due to free electrons in the metal.
Abstract: A mathematical model has been developed for heat transfer and fluid flow in thin films of molten metal during nanosecond pulsed laser irradiation. Heat conduction in the substrate is modeled using the finite-difference approach, while description of heat transfer and viscous flow in the film is based on the assumption of the large ratio of laser beam radius to film thickness and involves numerical solution of a partial differential equation for the thickness. The model includes the highly nonlinear dependence of evaporative flux on local interfacial temperature and positive disjoining pressure due to free electrons in the metal. Thermo-capillary stresses which result from radially nonuniform heating are identified as the main mechanism of removal of liquid metal from the irradiated area. Characteristic times of the process, as well as shapes of the molten surface, agree with experimental observations.

Book ChapterDOI
01 Aug 2006
TL;DR: In this article, a mixture of Al and Hg in a closed chamber under high pressure was released, leading to vaporization of the mercury at the melting temperature of aluminium and to the formation of a foam.
Abstract: Introduction Liquid foams are collections of gas bubbles uniformly dispersed in fluids and separated from each other by self-standing thin films. If the distance between bubbles is comparable to the bubble size one prefers to speak of bubble dispersions. In foams, bubble arrangements are usually disordered and gas volume fractions are high. If a liquid foam is solidified, a solid foam is obtained. Solid foams show many interesting properties which is the reason for their wide use, e.g. in civil engineering, chemistry or the food industry. Any liquid matter should be foamable and so is liquid metal. The prospect of being able to make light durable metallic foams already triggered research more than half a century ago. In 1943 Benjamin Sosnick attempted to foam aluminium with mercury. He first melted a mix of Al and Hg in a closed chamber under high pressure. The pressure was released, leading to vaporisation of the mercury at the melting temperature of aluminium and to the formation of a foam. Less hazardous processes were developed in the mid-1950s when it was realised that liquid metals could be more easily foamed if they were pre-treated to modify their properties. This could be done by oxidising the melt or by adding solid particles.

Journal ArticleDOI
TL;DR: In this article, a pure diffusion model was used to describe the helium transport by the Li film, and it was found that such model predicts a diffusion coefficient of (2.8± 0.6) −10 −11 ǫm 2 /s, based on the experimental retention measurements.