Contactless Surface Tension Measurement of Molten Oxides Using Oscillating Drop Method in an Aerodynamic Levitator

Abstract

Aerodynamic levitation stands as a contactless method for thermophysical property measurement of molten oxides at high temperatures, offering the advantage of eliminating sample contamination and enabling surface tension measurement through the oscillating drop method. However, the presence of external forces can lead to deformation and rotation of the levitated drop, eventually resulting in oscillation mode splitting and an underestimation of surface tension. This work investigated the oscillating drop method for accurate surface tension measurement in an aerodynamic levitator, using Al2O3 as a representative of oxides. The second-order resonance frequency was measured directly by eliminating oscillation mode splitting. The surface tension was then calculated using the Rayleigh equation. Damped oscillation analysis was combined with the frequency scan, reducing measurement uncertainty from 2.6-2.8% to 1.1%-1.5%. Within the temperature range of 2336K to 2923K, the surface tension of molten Al2O3 was found to be γ=-(4.071±2.688)×10-5(T-2327)+(0.7465±0.074) N/m. Furthermore, the effects of oscillation mode splitting on the surface tension measurement were also discussed.

Keywords: Surface tension, aerodynamic levitation, oscillating drop method, oscillation mode splitting, Resonance Frequency