Materials Research in Reduced Gravity: Thermophysical Properties (Levitation)
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Solidification Committee, TMS: Process Technology and Modeling Committee
Program Organizers: Wilhelmus Sillekens, European Space Agency; Michael Sansoucie, Nasa Marshall Space Flight Center; Robert Hyers, Worcester Polytechnic Institute; Douglas Matson, Tufts University; Gwendolyn Bracker, DLR Institute of Materials Physics in Space
Thursday 2:00 PM
March 23, 2023
Room: 30B
Location: SDCC
Session Chair: Wilhelmus Sillekens, European Space Agency; Birte Riechers, Federal Institute of Materials Research And Testing (BAM)
2:00 PM
Melt Flow Sensitivity to Sample Properties and Changes in the Electromagnetic Field During Oscillating Drop Experiments in EML: Gwendolyn Bracker1; R. W. Hyers1; 1University of Massachusetts
The oscillating drop technique is used to measure the surface tension and viscosity of a melt in electromagnetic levitation; however, this technique is sensitive to flow effects, such as turbulence. During oscillating drop measurements, the frequency and damping of surface oscillations are captured to determine the surface tension and viscosity of the melt at a given temperature. However, turbulence in the melt can dominate the damping coefficient and give the turbulent viscosity of the melt, a property of the flow and not of the melt itself. Transient magnetohydrodynamic models are used to evaluate the flow within the drop and the flow’s response to changes in the EML force field. The response of the flow depends on several variables including sample size, melt viscosity, melt conductivity, strength of the magnetic field, and duration of the excitation pulse.
2:20 PM
Contactless Material Properties Measurement using AC or DC Magnetic Fields: Valdis Bojarevics1; 1University of Greenwich
Electromagnetic levitation of liquid droplets for noncontact liquid material properties measurements is investigated using the high accuracy spectral numerical technique and compared to the available detailed experimental measurements at the International Space Station. The long-term numerical simulation of the full measurement cycle gives a deeper insight into the mechanics and dynamic regimes of the interacting surface oscillation and the internal flow circulation generated by the electromagnetic force. The example of the nickel-based alloy LEK94 provides experimental results replicated by the numerical predictions. At the same time, the internal recirculation velocities reach 0.40 m/s, the oscillation frequencies experience predictable temperature-dependent shifts from the theoretical Rayleigh analytical estimates, and the damping rate matches the laminar viscosity measured experimentally. In addition to the AC magnetic levitation, new ideas using a purely DC magnetic levitation are demonstrated both in the terrestrial gravity and microgravity space experiment conditions.
2:40 PM
AC Calorimetry of Liquid Metals in Electromagnetic Levitation: Comparison of Procedures in Microgravity and Terrestrial Conditions: Romain Pons1; Annie Gagnoud1; Didier Chaussende1; Olga Budenkova1; 1UGA/CNRS/SIMAP
Coupling of the electromagnetic levitation with microgravity conditions is favourable because of the possibility of using nearly symmetric electromagnetic fields. Furthermore, decoupling of the inductive heating from the sample positioning, as realised in the levitation system at the ISS, allows one to retrieve the thermal properties of the material using the two-zone model. Under terrestrial conditions, the necessity to overcome the gravity implies the application of a stronger and non-symmetrical EM field that inevitably leads to the forced liquid flow in the sample as well as the strong heating of the latter. Nevertheless, measurement of some properties is still possible with the help of numerical simulations. In the work the numerical modelling of the AC calorimetry is performed for a system in microgravity and for a setup used by the authors in the Terrestrial conditions. Acknowledgement: The research is supported by CNES via the materials’ science in microgravity programme.
3:00 PM
Convection during Modulation Calorimetry Experiments in Electromagnetic Levitation: Gwendolyn Bracker1; R. W. Hyers1; 1University of Massachusetts
During containerless processing, modulation calorimetry can be used to measure the specific heat and thermal conductivity of a molten sample. In electromagnetic levitation (EML), the power input by the levitation coils is modulated and the temperature response of the sample is analyzed to determine the thermophysical properties. However, the forced convection driven by the magnetohydrodynamic system accelerates the distribution of heat throughout the molten sample and increases the relaxation rate of thermal gradients within the sample. Recent advances in multiphysics models have incorporated the magnetohydrodynamics, fluid flow, and heat transfer to determine the distribution of temperature within the melt. By applying a transient model, a correlation between the observed temperature response and the thermal conductivity was examined in various systems. The updated models are being used to reevaluate data in the NASA-PSI system taken during the MSL-1 campaign to improve the accuracy of the measured thermal conductivity in various materials.
3:20 PM
Containerless Thermophysical Property Measurement of Bulk Metallic Glasses in the Liquid State under Microgravity: Markus Mohr1; Yue Dong1; Hans Fecht1; 1Ulm University
Bulk metallic glasses are advanced materials with several superior properties, such as extremely high elastic limit and high hardness, making them interesting materials for a number of applications. For the development of process simulations and for the calculation of thermodynamic functions, describing crystal nucleation and its absence – glass formation, knowledge of thermophysical properties in the solid and liquid phase are necessary. New processes, such as 3D-printing, can easily achieve the critical cooling rate, and hence one of the limits for production of large glassy parts can be overcome. During the last years, a number of BMG materials were investigated in the electromagnetic levitator ISS-EML on board the international space station. That way, a number of thermophysical properties (surface tension, viscosity, specific heat, total hemispherical emissivity) were determined for these samples.We give an overview over the ISS-EML capabilities and the thermophysical properties measured for some bulk metallic glasses.
3:40 PM Break
4:00 PM
Thermophysical Properties of Ge- and Si-based Semiconductors: Birte Riechers1; Yuansu Luo2; Bernd Damaschke3; Konrad Samwer3; Robert Maaß4; 1Federal Institute of Materials Research And Testing (BAM); 2Georg-August-Universität Göttingen ; 3Georg-August-Universität Göttingen; 4Federal Institute of Materials Research and Testing (BAM), University of Illinois at Urbana-Champaign
The semiconductors Si and Ge have been the workhorses for electronic hardware production for a long period of time. High-precision measurements of thermophysical properties of these semiconductor materials such as density, thermal expansion, surface tension, viscosity, and electrical resistivity, are crucial especially for modelling processing conditions and compliance with applicational demands. Due to the strong reactivity of the high-temperature melts of pure Ge and Si1-xGex (x = 0.75, 0.5, and 0.25) alloys, a contactless approach is most suitable for high-quality measurements. Thus, measurements were performed under low-gravity conditions using an electromagnetic levitator on board of the International Space Station within the framework of the European Space Agency project “SEMITHERM” (Investigations of thermophysical properties of liquid semiconductors in the melt and the undercooled state under microgravity conditions).The measured thermophysical properties will be discussed with an emphasis on trends connected to the compositional variation of all probed alloys and pure Ge.
4:20 PM Concluding Comments