Research Terms
This procedure for measuring the surface tension of molten metals or alloys utilizes electrostatic levitation and resonance to derive the values with sufficient accuracy for designing reliable metallic 3D prints. The use of 3D printing in the metals industry is growing rapidly, and analysts expect the market for metal 3D printing to be worth $10 billion by 2030. Advancements in metallic 3D printing would improve resource utilization so that unneeded tools could be melted down for 3D reprinting as other tools. Such on-site manufacturing could reduce the amount of refined metal needed for many projects, including long-term space missions. Accurate measurement of thermophysical properties like surface tension is crucial for various manufacturing methods, such as metal 3D printing and crystal growth. Traditional procedures for surface tension measurement fail when measuring high-temperature materials because of their high surface reactivity. Electrostatic levitation of liquid droplets can facilitate accurate surface tension measurement via pulse-decay analysis, but this can prove inaccurate if the droplets are highly viscous or the levitation system is noisy.
Researchers at the University of Florida and NASA have developed a system that accurately measures the surface tension of oscillating liquid droplets at high temperatures. Resonance analysis of an electrostatically levitated molten metal droplet measures its surface tension value, which enables accurate calculation of the 3D printing speed of a metal in order to eliminate aberrations in prints. This measurement system will undergo tests in microgravity, which should demonstrate its ability to determine surface tension.
Highly accurate system to measure surface tension of molten metals that can improve the quality of metallic 3D printing and crystal growth processes
The process measures the surface tension of a molten metal droplet that is electrostatically levitated in a vacuum (at least 10-7 torr). A range of continuously applied electric field oscillations causes a maximum deformation of the droplet at two distinct modes of oscillation. The droplet’s resonance then allows determination of its surface tension value at a specific temperature. The system works with high viscosity materials and remains accurate in extreme high-temperature environments . The surface tension value determines the 3D printing speed of a metal, so increased measurement accuracy can reduce or eliminate aberrations. This will improve the potential for on-site manufacturing, which would reduce the mass of metals and processing energy needed in space.
This device that uses electrostatic oscillations can measure interfacial tension between liquids in extreme environments with accuracy. Understanding interfacial tension is important for production in many industries, such as the chemical, cosmetic, and automobile industries. Available technologies can be used to determine interfacial tension only under certain conditions. Previously, samples with high melting points, high viscosities, or samples with similar densities could not be tested. Researchers at the University of Florida have developed a system and device that will overcome these obstacles and allow companies to better compare the interfacial tension of their product to a theoretical value. This will allow products to be adjusted for optimal fit for a prescribed use, such as improved semiconductor crystals that could result in better devices.
System and device for more accurate measure of interfacial tension even in extreme environments
This system and device is capable of characterizing or measuring interfacial tension between layers of liquids through the use of electrostatic oscillation. A dish with multiple liquids can be positioned between electrodes; a constant voltage superimposed with an alternating voltage is then applied across the electrodes. The amplitude of the alternating voltage can be increased to determine the amplitude at which the interface between the liquids begins to deflect or Faraday waves are created. This amplitude can characterize the interfacial tension between the liquids and be compared to the theoretical value.
This heat transfer system removes heat in zero gravity through conductance using vibrations induced by an AC electrostatic force. Heat transfer in microgravity is limited in the absence of buoyancy-driven convection. The conventional heat transfer approaches on Earth utilize buoyancy-driven flow and do not work in space, particularly in closed-loop systems requiring external pumps. As high-powered electronics become smaller and more powerful, heat must dissipate. Current thermal management breaks into active or passive thermal control systems.
Active thermal control systems require power input to operate, while passive thermal control systems do not. In active systems, pumped fluid systems decrease sensitivity to pressure drops, increase flow rate control, and achieve more precise temperature control within allowable margins. However, prominent disadvantages of active systems are the associated mechanical pump, requiring an electrical input that consumes part of the spacecraft’s power budget, and the potential cavitation of pumped systems, introducing possible system failures. On the other hand, passive systems do not use mechanical pumps, lowering the risks of system failures, but have a minimum startup heat flux. Electrostatic resonance can enhance heat transfer in microgravity.
Researchers at the University of Florida have developed a heat transfer control system able to function in zero-gravity environments. It removes heat through conductance using vibrations induced by an AC electrostatic force, showcasing a substantial increase in heat flux. The dissipated heat is applicable for heating and converting to mechanical energy.
Active heat transfer system uses AC electrostatic resonance to remove heat in microgravity
This heat transfer management system composes two water baths, at the top and bottom of the device, held at a constant temperature. Between the water baths sits an aluminum electrode at the top boundary and an indium tin oxide (ITO) coated glass electrode at the bottom boundary. Both these electrodes are sapphire, an electric insulator, directing the electricity to flow through the fluids as intended. A voltage and frequency are applied across the electrodes, causing electrostatic fields to create wavelike patterns for increasing the heat flux. This device combines the reliability of active thermal management and the ability of passive thermal management to avoid cavitation and mechanical failure.
