Liquid metal

About: Liquid metal is a research topic. Over the lifetime, 6947 publications have been published within this topic receiving 77785 citations. The topic is also known as: liquid alloy & liquid metal alloy.

Realization of switchable EIT metamaterial by exploiting fluidity of liquid metal

Abstract: Novel manipulation techniques for the propagation of electromagnetic waves based on metamaterials can only be performed in narrow operating bands, and this drawback is a major challenge for developing metamaterial-based practical applications. We demonstrate that the scattering of metamaterials can be switched and that their operating band can be tuned by introducing liquid metal in the design of functional metamaterials. The proposed liquid metal-based metamaterial is composed of a copper wire pair and a tiny pipe filled with a liquid metal, namely eutectic gallium-indium. The interference of the sharp magnetic resonance of the copper wire pair and the broad dipolar mode of the liquid metal rod lead to an electromagnetically induced transparency (EIT)-like spectrum. We experimentally demonstrate that this EIT-like behavior can be switched on or off by exploiting the fluidity of the liquid metal, which is useful for multi-frequency modulators. These findings will hopefully promote the development of fluid matter-based metamaterials for extending the operating band of novel electromagnetic functions.

On the nature of the armature-rail interface: liquid metal effects

Abstract: This is an experimental study of the nature of the armature-rail interface during hypervelocity launch in a railgun. It is part of a multidisciplinary modeling and experimental effort to improve the understanding of contact physics. Conditions that occurred at the interface are inferred from studies of the surfaces of recovered copper rails. Melt lubrication is observed at the armature-rail interface. Liquid aluminum metal from the contact faces of the solid aluminum armature forms at the armature-rail interface as a result of frictional and joule heating. The liquid aluminum is quenched by the relatively cool copper rail, and a quenched metal deposit is formed. Characterization of the deposit has shown a rapidly quenched microstructure. The mean grain size measured by transmission electron microscopy is 200 nm-the finest grain size reported for a melt quenched aluminum alloy film. The deposit thickness is less than 25 /spl mu/m and is rough with an oxidized surface. The thicker films crack, curl, and detach easily from the rail surface. The experiments were performed in a 25-mm square-bore railgun, with a ratio of interface current to armature contact width of 20-35 kA/mm. The liquid production rate by armature melting at the interface is found to be about 1 mg/C, We conclude that in solid armature railguns with sufficiently thick, liquid aluminum melt lubrication, the rail does not erode. Instead a deposit forms on the rail surface. Depending upon the film thickness and the quench stresses, the film detaches easily.

Magnetohydrodynamic flows in ducts with insulating coatings

Abstract: Effective insulation of the electrically conducting channel walls leads to a tolerable magnetohydrodynamic (MHD) pressure drop of liquid metal flows in self-cooled fusion reactor blankets. Such insulation prevents closed current circuits over conducting walls and reduces the total current, which determines the pressure drop and flow distribution caused by the interaction of the flowing liquid metal and the strong plasma-confining magnetic field. Several kinds of insulation are currently under development. One is the so-called flow channel insert technique, where the insulating ceramic is protected against the liquid metal by thin steel sheets. Recently, direct insulating ceramic coatings have been proposed which resist corrosion during the whole operation time of a fusion blanket. It is not necessary that these coatings provide perfect insulation. Even a finite coating resistance is enough to reduce the pressure drop by orders of magnitude. The aim of this paper is to provide material researchers and blanket designers with sufficient data on MHD insulation requirements. Changes in insulation properties occurring during the lifetime of the blanket due to impurities, corrosion, irradiation damage, or the presence of small cracks can be allowed up to a certain limit. The increase in the pressure drop and the change in flowmore » pattern are quantified, if the coating resistance falls below required limits.« less