Electrostatic containerless processing system

Rulison, Aaron J.; Watkins, J.; Zambrano, Brian

doi:10.1063/1.1148208

Cited by 66 publications

(33 citation statements)

References 10 publications

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“…Electrostatic levitation is based on the Coulomb forces acting on an electrically charged sample in a quasi-static electrical field [86]. A sample with a surface charge q and a mass m is levitated against gravity within a static electrostatic field as: (30) is the unit vector in z direction, i.e., parallel to the electrostatic field.…”

Section: Electrostatic Levitationmentioning

confidence: 99%

Non-Equilibrium Solidification of Undercooled Metallic Melts

Herlach

2014

Metals

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Abstract:If a liquid is undercooled below its equilibrium melting temperature an excess Gibbs free energy is created. This gives access to solidification of metastable solids under non-equilibrium conditions. In the present work, techniques of containerless processing are applied. Electromagnetic and electrostatic levitation enable to freely suspend a liquid drop of a few millimeters in diameter. Heterogeneous nucleation on container walls is completely avoided leading to large undercoolings. The freely suspended drop is accessible for direct observation of rapid solidification under conditions far away from equilibrium by applying proper diagnostic means. Nucleation of metastable crystalline phases is monitored by X-ray diffraction using synchrotron radiation during non-equilibrium solidification. While nucleation preselects the crystallographic phase, subsequent crystal growth controls the microstructure evolution. Metastable microstructures are obtained from deeply undercooled melts as supersaturated solid solutions, disordered superlattice structures of intermetallics. Nucleation and crystal growth take place by heat and mass transport. Comparative experiments in reduced gravity allow for investigations on how forced convection can be used to alter the transport processes and design materials by using undercooling and convection as process parameters.

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Section: Electrostatic Levitationmentioning

confidence: 99%

Non-Equilibrium Solidification of Undercooled Metallic Melts

Herlach

2014

Metals

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“…The NASA Marshall Space Flight Center (MSFC) electrostatic levitation (ESL) laboratory uses non-contact measurement methods to provide materials property and processing data [8]. Typical properties provided are the temperature dependence of thermophysical properties (e.g.…”

Section: Experimental Esl Facility At Nasa Marshall Space Flight Centermentioning

confidence: 99%

“…Levitated specimens are free from contact with a container, which permits studies of deeply undercooled melts, and high-temperature, highly reactive materials. Containerless processing provides data for studies of thermophysical properties, phase equilibria, metastable state formation, microstructure formation, undercooling, and nucleation.https://ntrs.nasa.gov/search.jsp?R=20180003488 2019-04-02T09:56:42+00:00ZThe NASA Marshall Space Flight Center (MSFC) electrostatic levitation (ESL) laboratory uses non-contact measurement methods to provide materials property and processing data [8]. Typical properties provided are the temperature dependence of thermophysical properties (e.g.…”

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confidence: 99%

Experiments Using a Ground-Based Electrostatic Levitator and Numerical Modeling of Melt Convection for the Iron-Cobalt System in Support of Space Experiments

Lee¹,

SanSoucie

2017

JOM

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Materials research is being conducted using an electromagnetic levitator installed in the International Space Station. Various metallic alloys were tested to elucidate unknown links among the structures, processes, and properties. To accomplish the mission of these space experiments, several ground-based activities have been carried out. This paper presents some of our ground-based supporting experiments and numerical modeling efforts. Mass evaporation of Fe50Co50, one of the flight compositions, was predicted numerically and validated by the tests using an electrostatic levitator (ESL). The density of various compositions within the Fe-Co system was measured with ESL. These results serve as reference data for the space experiments. The convection inside a electromagneticallylevitated droplet was also modeled to predict the flow status, shear rate, and convection velocity under various process parameters, which is essential information for designing and analyzing the space experiments of some flight compositions influenced by convection. INTRODUCTIONSince 2015, several materials experiments have been performed using the materials science laboratory electromagnetic levitator (MSL-EML) aboard the International Space Station (ISS). More than 50 principal investigators from 13 different countries have been participating in this space program. Thermophysical properties, transport phenomena, and glass/quasicrystal formation of various alloys are being studied using MSL-EML. To increase the chance of success in the space experiments, the team has meticulously planned and prepared for their science experiments. The safety aspects, mass evaporation [1] and thermophysical properties [2-4] of each sample have been measured as part of the ground support program.The measurement of mass evaporation is important. Evaporation often causes composition shifts of tested alloys resulting from preferential evaporation of volatile species. Such composition shifts can be reduced by limiting superheating and time for thermal hold during property measurements. On the other hand, evaporated materials may end up as aerosols, which can be hazardous to the health of the astronauts. Otherwise the evaporated materials will deposit on the optics, obscuring measurements, or on the coils. Excessive coil deposition can cause flaking of deposited materials, cross-contamination, short circuiting, and arcing. Each batch has 18 samples, and the amount of mass evaporation of each sample is different depending on the composition and thermal history. After discussion among scientists, the thermal cycles of each samples are adjusted such that the total amount of mass evaporation does not exceed a designated value.For flight samples whose internal convection is of interest, numerical models were developed [5] and used [6]. The developed numerical models have been used to predict the convection status under an anticipated combination of process parameters. The status of convection affects phase selection during solidification of metal alloys which exhibit ...

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“…An advanced ESL is described by Rulison et al [5]. This instrument is installed at NASA's Marshall Space Flight Center in Alabama and used in ground-based research under containerless and high vacuum conditions.…”

Section: Electrostatic Levitation (Esl)mentioning

confidence: 99%