Jkr. Weber et al., AEROACOUSTIC LEVITATION - A METHOD FOR CONTAINERLESS LIQUID-PHASE PROCESSING AT HIGH-TEMPERATURES, Review of scientific instruments, 65(2), 1994, pp. 456-465
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.