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Thermophysical properties measurement of NiBSi on-board of parabolic flights
Quentin Champdoizeau, Jonas Valloton and Hani Henein
A NiBSi sample was processed using the TEMPUS electromagnetic levitation facility on board of parabolic flights within the frame of the European Space Agency project NEQUISOL and THERMOLAB. Six cycles of melting and free cooling were analyzed to measure the density, surface tension and viscosity of the alloy using the oscillating drop method, with a few measurements obtained below the melting point ~1 230 mT C° . The density measurements are 5-6% lower on average than the ideal model for a Ni-2.2 wt% B-2.8 wt% Si alloy, indicating a positive excess volume. The surface tension results are lower than expectations for this Nickel-based system and show a positive temperature coefficient which could indicate contamination by oxygen. Fitting of an adsorption model to the measurements reveal that a contamination by 79±6ppm of oxygen suffice to explain the deviation. The viscosity results are significantly higher than expected for a Ni-based alloy. These viscosity results are potentially affected by the modulation of the oscillations due to nonlinearities and rotation of the sample despite the Reynolds number of the oscillations indicating a laminar internal flow.
Keywords: NiBSi, EML, microgravity, oscillating droplet, density, viscosity, surface tension
DOI: 10.32908/hthp.v54.2037