Aero-acoustic levitation: A method for containerless liquid-phase processing at high temperatures

Abstract

A method for containerless liquid‐phase processing was developed which has practical application in process and property research on virtually any material which is involatile at the melting point. It combines aerodynamic and acoustic forces to support and position the levitated material. The design provides forced convection control of the thermal boundary in the gas surrounding beam‐heated specimens, which stabilizes the acoustic forces and allows acoustic positioning necessary to stabilize the aerodynamic levitation forces on molten materials. Beam heating and melting at very high temperatures was achieved. Experiments were conducted on specimens with diameters in the range 0.25–0.4 cm, of density up to 9 g/cm³, at temperatures up to 2700 K, and in oxygen, air, or argon atmospheres. Unique liquid‐phase processing results included deep undercooling of aluminum oxide, glass formation at exceptionally small cooling rates, complete melting and undercooling of YBa₂Cu₃O_x superconductor materials, direct formation of the YBa₂Cu₃O_x from the liquid phase, and the vaporization of volatile constituents from a low‐liquefaction point glass to form a refractory, high melting material. The application of rapid containerless batch processing operations to materials synthesis is discussed.