Galinstan is a brand-name and a common name for any member of a family of liquid metaleutectic alloys whose composition is mainly consisting ofgallium, indium, and tin. Such eutectic alloys are liquids at room temperature, typically melting at, while commercial Galinstan melts at. Galinstan is composed of 68.5% Ga, 21.5% In, and 10.0% Sn. 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.
Name
The name “Galinstan” is a portmanteau of gallium, indium, and stannum. The brand-name “Galinstan” is a registered trademark of the German company Geratherm Medical AG, but “galinstan” is in common use for any eutectic alloy of gallium, indium, and tin.
Galinstan tends to be “wet” and adhere to many materials, including glass, which limits its use compared to mercury.
Uses
Galinstan 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 is also electrically conductive, and so needs to be applied more carefully than regular non-conductive compounds. Two thermal interfaces have already been developed: Thermal Grizzly Conductonaut and Coolaboratory Liquid Ultra, with thermal conductivities of 73 and 38.4 W/mK respectively. However, they must be carefully applied with a Q-tip, and cannot be used on aluminum heatsinks as aforementioned. Galinstan 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.
X-ray equipment
Extremely high-intensity sources of 9.25 keV X-rays for X-ray phase microscopy of fixed tissue, from a focal spot about 10 μm × 10 μm, and 3-D voxels of about one cubic micrometer, may be obtained with an X-ray source that uses a liquid-metal galinstan anode. The metal flows from a nozzle downward at a high speed, and the high-intensity electron source is focused upon it. The rapid flow of metal carries current, but the physical flow prevents a great deal of anode heating, and the high boiling point of galinstan inhibits vaporization of the anode.
