Noncontact Thermophysical Property Measurements of Refractory Metals Using an Electrostatic Levitator

The use of a containerless technique for materials processing has many technological and scientific advantages. The absence of a crucible allows the handling of chemically reactive materials such as molten refractory metals, alloys, or semiconductors, and eliminates the risk of sample contamination in overheated and in undercooled states (liquid phase below melting temperature). This offers excellent opportunities to characterize the structure of materials and to determine accurately their thermophysical properties in those states. The lack of a crucible also suppresses nucleation induced by the walls of a container (heterogeneous nucleation), thus increasing the possibility of producing new materials such as metallic glasses.

Several levitation methods, including acoustic, electromagnetic, aerodynamic, and electrostatic have been applied for thermophysical property measurements. The electromagnetic levitation method has been most popularly used for metal samples because instrumentation is rather simple and compatible with high vacuum. Density, surface tension, electrical resistivity, spectral emissivity, and thermal conductivity of conductive materials are currently measured using this method [1–4].