AEROACOUSTIC LEVITATION - A METHOD FOR CONTAINERLESS LIQUID-PHASE PROCESSING AT HIGH-TEMPERATURES

A method for containerless liquid-phase processing was developed which has practical application in process and property research on virtual ly 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 stabiliz es the acoustic forces and allows acoustic positioning necessary to st abilize the aerodynamic levitation forces on molten materials. Beam he ating and melting at very high temperatures was achieved. Experiments were conducted on specimens with diameters in the range 0.25-0.4 cm, o f density up to 9 g/cm(3), at temperature up to 2700 K, and in oxygen, air, or argon atmospheres. Unique liquid-phase processing results inc luded deep undercooling of aluminum oxide, glass formation at exceptio nally small cooling rates, complete melting and undercooling of YBa2Cu 3Ox superconductor materials, direct formation of the YBa2Cu3Ox from t he liquid phase, and the vaporization of volatile constituents from a low-liquefaction point glass to form a refractory, high melting materi al. The application of rapid containerless batch processing operations to materials synthesis is discussed.