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One fun thing you can do right away with the liquid metal alloy is make your own mirrors. All it takes is a piece of glass and a cotton swab.Dip the cotton swab in the vial, and twirl it around to coat it with the liquid metal alloy.Now rub the coated swab on the glass (in the phot we are using a glass microscope slide). The metal sticks to the glass, and makes an opaque reflective coating.More fun thingsThere are lots of things you can do with liquid metal: Make thermometers Make barometers Make tilt meter seismographs Make non-conductive objects conductive Make electrodes that conform to varying surfaces Experiment with magnetohydrodynamics Wiggle it with high frequency electricity Use it to conduct high energy sound Replace mercury in spinning telescope mirrors If you need a shiny surface, a dilute solution of hydrochloric acid can be placed on the surface, or you can use a light coating of mineral oil. Both will prevent the slow oxidation of the metal that occurs over time.How does it do that?Gallium is an element (atomic number 31, right below aluminum and just to the right of zinc in the periodic table of the elements). It starts out with a very low melting point already, but we can add some other elements to get an even lower melting point.Right below gallium in the periodic table isindium(element 49). Just to the right of indium istin(element 50).When these elements are combined, their atoms bind together into a compound. The molecules of that compound do not bind to one another as much as the atoms of the original metals bound to each other. This lowers the melting point.There are many ways to combine the three metals:Each combination will have a slightly different melting point. Which do you think has the lowest melting point? This might make a good science fair experiment.A mixture of 76% gallium and 24% indium melts at 16° Celsius (61° Fahrenheit). Both gallium and this combination can be supercooled. That means that once melted, they can stay liquid even though they are cooled well below their melting points. Eventually a small crystal forms, and starts the whole batch solidifying, but small amounts can be kept supercooled for quite a while.The gallium-indium alloy is more reflective than mercury, and is less dense, so it is being explored as a replacement for mercury in spinning liquid mirrors for astronomical telescopes.
The low melting point alloy series generally contains Bi, Pb, Sn, Cd, In, Ga, Zn, Sb, and other low melting point alloys, also known as "fusible alloys". It is generally believed that their melting points are all below 310°. According to the characteristics of its melting point, it can be divided into two categories: one is called eutectic alloy, and the other is non-eutectic alloy. The melting point of all low melting point alloys is lower than the melting point of any of the pure metals of the alloys formed. The melting point of the eutectic alloy is stable. The melting point (flow temperature) of the non-eutectic alloy varies depending on the test method, the quality of the alloy, the measurement position, the heating rate, and other factors.Thermal interface materials have the following characteristics:(1) High thermal conductivity;(2) High flexibility, ensuring that the material can fill the gap of the contact surface most fully under the condition of low installation pressure, and the contact thermal resistance between the thermal interface material and the contact surface is small;(3) Insulation;(4) Easy to install and detachable;(5) Wide applicability, can be used to fill small gaps, but also to fill large gaps.
Galinstan is a brand-name and a common name for a liquid metal alloy whose composition is part of a family of eutectic alloys mainly consisting of gallium, indium, and tin. Such eutectic alloys are liquids at room temperature, typically melting at +11 °C (52 °F), while commercial Galinstan melts at −19 °C (−2 °F).An example of a typical eutectic mixture is 68% Ga, 22% In, and 10% Sn (by weight) though proportions vary between 62–95% Ga, 5–22% In, 0–16% Sn (by weight) while remaining eutectic; the exact composition of the commercial product “Galinstan” is not publicly known.Due to the low toxicity and low reactivity of its component metals, galinstan finds use as a replacement for many applications that previously employed the toxic liquid mercury or the reactive NaK (sodium–potassium alloy).Physical propertiesBoiling point: > 1300°CMelting point: −19°CVapour pressure: < 10−8 Torr (at 500°C)Density: 6.44 g/cm3 (at 20°C)[3]Solubility: Insoluble in water or organic solventsViscosity: 0.0024 Pa·s (at 20°C)Thermal conductivity: 16.5 W·m−1·K−1Electrical conductivity: 3.46×106 S/m (at 20°C)Surface tension: s = 0.535 - 0.718 N/m (at 20°C, dependent on producer)Specific heat capacity: 296 J·kg−1·K−1Galinstan tends to be “wet” and adhere to many materials, including glass, which limits its use compared to mercury.UsesGalinstan is commercially used as a mercury replacement in thermometers due to its nontoxic properties, but the inner tube surface must be coated with gallium oxide to prevent the alloy from wetting the glass surface.Galinstan has higher reflectivity and lower density than mercury. In the field of astronomy it is considered as a replacement for mercury in liquid mirror telescopes.Galinstan may be used as a thermal interface for computer hardware cooling solutions, though major obstacles for widespread use are its cost and aggressive corrosive properties (it corrodes many other metals such as aluminium by dissolving them). It is also electrically conductive, and so needs to be applied more carefully than regular non-conductive compounds.It is difficult to use for cooling fission-based nuclear reactors, because indium has a high absorption cross section for thermal neutrons, efficiently absorbing them and inhibiting the fission reaction. Conversely, it is being investigated as a possible coolant for fusion reactors. Unlike other liquid metals used in this application, such as lithium and mercury, the nonreactivity makes galinstan a safer material to use.
Liquid metals, such as alloys of bismuth, gallium and indium, potentially offer both low interfacial resistance and high conductivity. Several alloys of gallium with very low melting points have also been identified as potential liquid metal interface materials. Thermal performance of such an interface would be more than one order of magnitude greater than many adhesives typically in use.LMA alloys as a thermal interface material offer superior thermal performance due to their high thermal conductivities and low contact resistance, resulting from excellent surface wetting. Reworkability, ease of handling, and a lack of cure make this attractive in a high volume setting. The various failure mechanisms which have plagued the past and present LMA products will be mitigated by applying a multidisciplinary approach to the challenge. Liquid metals flow quite well. The solid structures or phases proposed for incorporation within the thermal interface address the basic problem of getting an LMA to stay put when in service. These structures increase the surface contact area with the LMA in the thermal interface. As long as the total solid-liquid interface energy is less than the interface energy of the liquid-gas and solid-gas interfaces it replaces, the LMA will minimize its surface energy by wetting the surfaces within the interface. The LMA may still wet the surface adjacent to the thermal interface if it is the same wettable surface used under the die, particularly when acted upon by an additional force. Additional forces will arise from shock, vibration, and CTE mismatches between the LMA and other components. Once the LMA has wet the surface adjacent to, but outside the thermal interface, it is doubtful surface tension alone will retain it within the interface when acted upon by external forces. Others have proposed to address this difficulty with gaskets to contain the LMA and fillers or non-eutectic (slushy) compositions to increase its viscosity. We have found that simply modifying the surface around the thermal interface so that the LMA will not wet it is sufficient to contain the LMA within the interface during shock, vibration, and temp cycling. It is conceivable that if excess LMA were incorporated during assembly, this excess could end up airborne from shock or vibration. Therefore, LMA TIM should be deployed in closed cavities where no opportunities for shorts or adverse reactions with other metals exist.
Galinstan is a brand-name and a common name for a liquid metal alloy whose composition is part of a family of eutectic alloys mainly consisting of gallium, indium, and tin. Such eutectic alloys are liquids at room tem`perature, typically melting at +11 °C (52 °F), while commercial Galinstan melts at −19 °C (−2 °F).An example of a typical eutectic mixture is 68% Ga, 22% In, and 10% Sn (by weight) though proportions vary between 62–95% Ga, 5–22% In, 0–16% Sn (by weight) while remaining eutectic; the exact composition of the commercial product “Galinstan” is not publicly known.Due to the low toxicity and low reactivity of its component metals, galinstan finds use as a replacement for many applications that previously employed the toxic liquid mercury or the reactive NaK (sodium–potassium alloy).Physical properties·Boiling point: > 1300°C· Melting point: −19°C· Vapour pressure: < 10−8 Torr (at 500°C)· Density: 6.44 g/cm3 (at 20°C)[3]· Solubility: Insoluble in water or organic solvents· Viscosity: 0.0024 Pa·s (at 20°C)· Thermal conductivity: 16.5 W·m−1·K−1· Electrical conductivity: 3.46×106 S/m (at 20°C)· Surface tension: s = 0.535 - 0.718 N/m (at 20°C, dependent on producer)· Specific heat capacity: 296 J·kg−1·K−1Galinstan tends to be “wet” and adhere to many materials, including glass, which limits its use compared to mercury.UsesGalinstan is commercially used as a mercury replacement in thermometers due to its nontoxic properties, but the inner tube surface must be coated with gallium oxide to prevent the alloy from wetting the glass surface.Galinstan has higher reflectivity and lower density than mercury. In the field of astronomy it is considered as a replacement for mercury in liquid mirror telescopes.Galinstan may be used as a thermal interface for computer hardware cooling solutions, though major obstacles for widespread use are its cost and aggressive corrosive properties (it corrodes many other metals such as aluminium by dissolving them). It is also electrically conductive, and so needs to be applied more carefully than regular non-conductive compounds.It is difficult to use for cooling fission-based nuclear reactors, because indium has a high absorption cross section for thermal neutrons, efficiently absorbing them and inhibiting the fission reaction. Conversely, it is being investigated as a possible coolant for fusion reactors. Unlike other liquid metals used in this application, such as lithium and mercury, the nonreactivity makes galinstan a safer material to use.
Significant manufacturing cost reductions can be realized with lower-temperature surface mount processing by increasing yields and using less expensive components and boards. A lower-melting-point solder alloy (nominal composition Sn-41.75Pb-8Bi-0.5Ag) has been developed that enables significant reductions in peak reflow temperatures during surface-mount assembly. The solder alloy is compatible with standard Pb-Sn surface finishes, melts within the temperature range of ~166-172°C, and has promising mechanical properties.After establishing an optimum ternary composition of Sn-42Pb-8Bi, quaternary additions were examined for additional beneficial effects on the melting character of the alloy. Silver additions were the most beneficial—peak thermal and mechanical benefits were obtained at ~0.5%Ag content. The solidus temperature of this alloy is ~166°C, the primary liquid temperature is ~172°C, and there is a very small (approximately 2-3%) residual amount of lead-rich solids that do not completely melt until 178°C. This melting character suggests that it may be feasible to lower peak reflow temperatures in surface mount assembly processes by as much as 10-15°C using the silver-doped alloy. Compositional fluctuations of silver below 0.2% are not effective in providing melting point depressions and silver contents in excess of 0.8% begin to form phases with melting points well beyond that of eutectic 63Sn-37Pb.Experiments with fully populated boards having greater local thermal masses are in progress to determine the lowest peak reflow temperatures for given applications. However, it does seem quite clear that surface mount soldering with a Sn-41.75Pb-8Bi-0.5Ag solder paste can be done at temperatures significantly lower than those currently in use in order to relieve many yield problems associated with moisture and temperature sensitivity in surface mount assembly.
The low melting point alloy and polymer composite can be used not only for the preparation of composite materials with high electrical conductivity, but also for the preparation of composite materials with high thermal conductivity. In Japan, high thermal conductivity plastics prepared by combining low melting point alloys with polymers have been successfully developed.Another form of polymer-based conductive composites that use a low melting point alloy as a conductive filler is an adhesive. In the electronics industry, in order to replace lead-containing solders, conductive adhesives composed of polymer collectives and conductive fillers such as silver sheets have been developed. However, such conventional conductive adhesives have high and unstable connection resistance and low impact strength. In order to improve it, a low-melting alloy was added to the conventional conductive adhesive to produce a new conductive adhesive. The connection structure of the new conductive adhesive was characterized by SEM, optical microscope, etc. The results showed that after the resin was cured, a metal connection was established between the conductive particles and between the conductive particles and the circuit. This new type of conductive adhesive has a much lower volume resistance than conventional conductive adhesives, especially the connection structure formed in the circuit has a lower initial continuous resistance, and a more stable connection resistance than using a conventional conductive adhesive, all in the conductive adhesive The use of a low melting point alloy as a conductive filler can reduce the adhesive resistivity and improve the connection conductivity. The combination of the low melting point alloy and the polymer can improve the processing property of the polymer. Under appropriate preparation conditions, the obtained composite material has high electrical conductivity and excellent mechanical properties. In other words, the price performance and performance of the material are perfectly unified. It is beyond any other filler system such as carbon black, carbon fiber, metal fiber, metal foil and so on. This shows that low melting point alloys are a very promising functional material.
Liquid metals have a very large thermal conductivity, which allows them to achieve large heat transfer coefficients and achieve efficient energy exchange at low temperatures. Since this memory condition relies on efficient molecular energy transfer, large single-phase results can be obtained within simple geometries. In other words, a large increase in the heat transfer coefficient of liquid metal (3 to 20 times) is possible. The old one that significantly increased the heat transfer coefficient should allow higher heat flux during work, while maintaining a constant temperature This is a major limitation of the design of the former molten salt receiver. Therefore, in the receiver area, the liquid metal can also reduce the overall capital investment; in addition, higher receiving efficiency can be achieved by improving the heat transfer performance. Usually in a thermal power station, the ideal result is to have a higher temperature to achieve greater thermodynamic efficiency. The solar photovoltaic efficiency as a whole should also consider the impact of optical aspects and receiver performance. The state-of-the-art central receiving system is a subcritical steam Rankine cycle operated by nitrate. In general, when operating to a high steam temperature of 630 ° C, the overall photoelectric efficiency of wet and dry condensers increases by 8-12%. However, the higher temperatures required to implement this advanced power cycle cannot be achieved with molten salts at all, as their temperature is limited to 560 ° C. Direct application of solar thermochemical processes at high operating temperatures is feasible. The development of industrial processes in chemical reactors at high temperatures is necessary, and molten metal can stably perform the function of a thermal fluid.Application of high temperature liquid metal in heat engine cycle700 ° C ultra-supercritical steam turbine cycle: With the development of solar modules (receivers, storage systems, and solar modules) compared to other high-temperature concepts, the relatively low development demand for future 700 ° C ultra-supercritical steam power modules can be achieved through liquid Heat transfer provided. An outlet temperature of 700 ° C is necessary for such receivers, and nickel-based alloys can help overcome physical issues. In the temperature range corresponding to the receiving system and storage system, it is necessary to develop a steam cycle temperature exceeding 700 ° C. It can be seen that the main risks related to the feasibility of this concept are nickel welding problems and transient strains, as well as corrosion problems.Open gas turbine cycle: the lowest 600 ℃ gas in the combined cycle. The steam power module has been commercialized and can be improved on the basis of the advanced technology of current coal-fired and gas-fired power plants. Adopted-solar-gas turbines have significant advantages over other conventional Taigangneng power plants. Although there is no commercial scale, the concept of using compressed air as the heat sink receiver has been extensively studied.Closed Gas Turbine Cycle: In a closed cycle, it can be used to replace air with an optional inert gas, resulting in more efficient power conversion. Similarly, the high-temperature heat energy collected in an open cycle must be transferred by a heat exchanger or indirect or direct contact type. Direct contact heat exchangers are attractive from a cost reduction point of view, but practical issues involving pressure seals and Rankine-Steam delivery to steam turbines need to be addressed. Similar to the open gas turbine cycle, the closed cycle needs additional development. The main method to reduce costs is related to the partial load in the closed Brayton cycle.
Afusible alloyis ametalalloycapable of being easilyfused, i.e. easily meltable, at relatively low temperatures. Fusible alloys are commonly, but not necessarily,eutecticalloys. Sometimes the term "fusible alloy" is used to describe alloys with amelting pointbelow 183°C (361°F; 456K). Fusible alloys in this sense are used forsolder.IntroductionLow-melting alloys can be divided into the following categories:1. Mercury-containing alloys2. Only alkali metal-containing alloys3. Gallium-containing alloys (but neither alkali metal nor mercury)4. Only bismuth, lead, tin, cadmium, zinc, indium, and sometimes thallium-containing alloys5. Other alloys (rarely used)6. Some reasonably well-known fusible alloys are Wood's metal, Field's metal, Rose metal, Galinstan, and NaK.Applications Melted fusible alloys can be used as coolants as they are stable under heating and can give much higher thermal conductivity than most other coolants; particularly with alloys made with a high thermal conductivity metal such as indium or sodium. Metals with low neutron cross-section are used for cooling nuclear reactors.related articles:New composite material-low melting alloy
Liquid metal corrosion on the mechanism and the way is different from common chemical corrosion medium, generally no electrochemical reactions, but the erosion, cavitation and embrittlement phenomenon under the action of physical chemistry results it is easy to occur at between liquid metal and metal forming, caused by solid metal damage and contamination of liquid metal, the main corrosion means has the following kinds:1) Dissolution of liquid metal: this dissolution process is mainly controlled by the solubility of solid metal in liquid metal at a given temperature.2) Corrosion caused by contamination in liquid metals: the presence of oxygen in liquid metals may lead to oxidation of the surface.3) Grain boundary corrosion: corrosion caused by a selective reaction between a liquid metal and a solid material along the grain boundary.4) Transport and deposition of matter: in a liquid metal system, elements are dissolved at high temperatures due to temperature heterogeneity, and then deposited at low temperatures.5) Liquid metal embrittlement: this is a phenomenon, such as the embrittlement of austenitic stainless steel in the zinc environment.6) Erosion: mechanical erosion of liquid metal. Note: some physical processes, such as the physical dissolution of metallic materials in some liquid metals, may also be classified as metallic corrosion. Corrosion of metals in solution is an electrochemical reaction. Contact between metallic materials and liquid metals exists in many practical applications, such as welding, casting, brazing, hot dip plating, etc.In many cases, metal materials and the structures made from them, in the natural environment or under working conditions, due to chemical or electrochemical interaction with the environment medium caused by deterioration and destruction, this phenomenon is called corrosion.
