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.

A general approach to composites containing nonmetallic fillers and liquid gallium

Abstract: 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.

Vacuum-filling of liquid metals for 3D printed RF antennas

Abstract: This paper describes a facile method to fabricate complex three-dimensional (3D) antennas by vacuum filling gallium-based liquid metals into 3D printed cavities at room temperature. To create the cavities, a commercial printer co-prints a sacrificial wax-like material with an acrylic resin. Dissolving the printed wax in oil creates cavities as small as 500 μm within the acrylic monolith. Placing the entire structure under vacuum evacuates most of the air from these cavities through a reservoir of liquid metal that covers a single inlet. Returning the assembly to atmospheric pressure pushes the metal from the reservoir into the cavities due to the pressure differential. This method enables filling of the closed internal cavities to create planar and curved conductive 3D geometries without leaving pockets of trapped air that lead to defects. An advantage of this technique is the ability to rapidly prototype 3D embedded antennas and other microwave components with metallic conductivity at room temperature using a simple process. Because the conductors are liquid, they also enable the possibility of manipulating the properties of such devices by flowing metal in or out of selected cavities. The measured electrical properties of fabricated devices match well to electromagnetic simulations, indicating that the approach described here forms antenna geometries with high fidelity. Finally, the capabilities and limitations of this process are discussed along with possible improvements for future work.

Melt conditioning by advanced shear technology (MCAST) for refining solidification microstructures

Abstract: MCAST (melt conditioning by advanced shear technology) is a novel processing technology developed recently for conditioning liquid metal prior to solidification processing. The MCAST process uses a twin screw mechanism to impose a high shear rate and a high intensity of turbulence on the liquid metal, so that the conditioned liquid metal has uniform temperature, uniform chemical composition and well-dispersed and completely wetted oxide particles with a fine size and a narrow size distribution. The microstructural refinement is achieved through an enhanced heterogeneous nucleation rate and an increased nuclei survival rate during the subsequent solidification processing. In this paper we present the MCAST process and its applications for microstructural refinement in both shape casting and continuous casting of light alloys.

Characteristics of a gallium liquid metal field emission ion source

Abstract: Discusses the emission of positive ions from liquid metals under the action of high electric fields. High brightness sources are being developed with a variety of applications in mind. The basic principles of such sources are discussed and the design and experimental behaviour of a gallium source are described in detail. Measurements of the current-voltage characteristics of the source, together with the angular distribution of the beam are presented. The current-voltage behaviour is found to be in agreement with the predictions of a simple space charge model. Field ion creation mechanisms require liquid metal emitting features of submicron dimensions and this does not appear to be consistent with space-charge considerations and the best available microscopic observations. This apparent paradox can be resolved if a highly mobile emitting feature is assumed to exist.

Flow of molten slag and iron at 1500 °C to 1600 °C through packed coke beds

Abstract: The blast furnace dripping zone is of great importance to the mass transfer of elements such as sulfur, carbon, and silicon, to and from the liquid metal phase. To understand mass transfer in the dripping zone, not only mass-transfer reactions and kinetics should be known, but the flow phenomena and process dynamics should be understood as well. The flow of hot metal and slag in the dripping zone was studied in experiments, in which liquid slag and metal trickled through a packed coke bed at 1500 °C to 1600 °C. The results indicate that slag and iron flow concurrently in a funicular type of flow. The iron flows through the core of the voids in the bed and is enveloped by slag, which flows filmwise in between the coke and the iron. This mode of flow allows for a large contact area between slag and iron, through which mass can be transferred. While flowing, the liquid can only pass and access a void, if and when the fluid capillary pressure at the void neck can be overcome. As a result, liquid droplets collect into rivulets. These rivulets flow down, along the accessible voids, using only a part of the available volume. The residence times of the fluids in the bed depend partly on the length of the pathway and are a function of the bed structure, the void neck distribution, and the stochastics of the flow. During flow, slag may react with coke, thus changing the distribution of the slag composition, and its sulfur capacity. In addition, the residence time distribution of the slag and the liquid holdup change as a result of these reactions. Holdup and residence time distribution of the liquids as measured in the experimental setup could not be modeled quantitatively, most likely due to the doubly distributed nature (in space and in time) of the model parameters, induced by reactions between slag, coke, and liquid metal.