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  • 1
    Electronic Resource
    Electronic Resource
    Noncontact technique for measuring surface tension and viscosity of molten materials using high temperature electrostatic levitation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2796-2801 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new, noncontact technique is described which entails simultaneous measurements of the surface tension and the dynamic viscosity of molten materials. In this technique, four steps were performed to achieve the results: (1) a small sample of material was levitated and melted in a high vacuum using a high temperature electrostatic levitator, (2) the resonant oscillation of the drop was induced by applying a low level ac electric field pulse at the drop of resonance frequency, (3) the transient signals which followed the pulses were recorded, and (4) both the surface tension and the viscosity were extracted from the signal. The validity of this technique was demonstrated using a molten tin and a zirconium sample. In zirconium, the measurements could be extended to undercooled states by as much as 300 K. This technique may be used for both molten metallic alloys and semiconductors. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149797
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  • 2
    Electronic Resource
    Electronic Resource
    An electrostatic levitator for high-temperature containerless materials processing in 1-g (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2961-2970 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article discusses recent developments in high-temperature electrostatic levitation technology for containerless processing of metals and alloys. Presented is the first demonstration of an electrostatic levitation technology which can levitate metals and alloys (2–4 mm diam spheres) in vacuum and of superheating-undercooling-recalescence cycles which can be repeated while maintaining good positioning stability. The electrostatic levitator (ESL) has several important advantages over the electromagnetic levitator. Most important is the wide range of sample temperature which can be achieved without affecting levitation. This article also describes the general architecture of the levitator, electrode design, position control hardware and software, sample heating, charging, and preparation methods, and operational procedures. Particular emphasis is given to sample charging by photoelectric and thermionic emission. While this ESL is more oriented toward ground-based operation, an extension to microgravity applications is also addressed briefly. The system performance was demonstrated by showing multiple superheating-undercooling-recalescence cycles in a zirconium sample (Tm=2128 K). This levitator, when fully matured, will be a valuable tool both in Earth-based and space-based laboratories for the study of thermophysical properties of undercooled liquids, nucleation kinetics, the creation of metastable phases, and access to a wide range of materials with novel properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144475
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  • 3
    Electronic Resource
    Electronic Resource
    Laser-induced rotation of a levitated sample in vacuum (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4652-4655 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method of systematically controlling the rotational state of a sample levitated in a high vacuum using the photon pressure is described. A zirconium sphere was levitated in the high-temperature electrostatic levitator and it was rotated by irradiating it with a narrow beam of a high-power laser on a spot off the center of mass. While the laser beam heated the sample, it also rotated the sample with a torque that was proportional both to the laser power and the length of the torque arm. A simple theoretical basis was given and its validity was demonstrated using a solid zirconium sphere at ∼2000 K. This method will be useful to systematically control the rotational state of a levitated sample for the containerless materials processing at high temperature. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150127
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  • 4
    Electronic Resource
    Electronic Resource
    A noncontact measurement technique for the specific heat and total hemispherical emissivity of undercooled refractory materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 695-700 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A noncontact measurement technique for the constant pressure specific heat (cpl) and the total hemispherical emissivity (εTl) of undercooled refractory materials is presented. In purely radiative cooling, a simple formula which relates the post-recalescence isotherm duration and the undercooling level to cpl is derived. This technique also allows us to measure εTl once cpl is known. The experiments were performed using the high-temperature high-vacuum electrostatic levitator at JPL in which 2–3 mm diameter metallic samples can be levitated, melted, and radiatively cooled in vacuum. The averaged specific heats and total hemispherical emissivities of Zr and Ni over the undercooled regions agree well with the results obtained by drop calorimetry: cpl,av(Zr)=40.8±0.9 J/mol K, εTl,av(Zr)=0.28±0.01, cpl,av(Ni)=42.6±0.8 J/mol K, and εTl,av(Ni)=0.16±0.01.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145087
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  • 5
    Electronic Resource
    Electronic Resource
    A noncontact measurement technique for the density and thermal expansion coefficient of solid and liquid materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3175-3181 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A noncontact measurement technique for the density and the thermal expansion coefficient of refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2–3 mm diam samples can be levitated, melted, and radiatively cooled in vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045–1565 °C. The result for the liquid phase density can be expressed by ρ=8.848+(6.730×10−4)×T (°C) g/cm3 within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by β=(9.419×10−5) −(7.165×10−9)×T (°C) K−1 within 0.2% accuracy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147584
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  • 6
    Electronic Resource
    Electronic Resource
    Noncontact electrical resistivity measurement technique for molten metals (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 3628-3633 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A noncontact technique of measuring the changes in electrical conductivity (or resistivity) of conducting liquids is reported. The technique is based on a conducting drop that is levitated by the high-temperature electrostatic levitator in a high vacuum. This technique, which utilizes the principle of the asynchronous induction motor, measures the relative changes in torque as a function of temperature by applying a rotating magnetic field to the sample. Changes in electrical resistivity are related to the changes in measured torque using the formula developed for the induction motor. Validity of this technique was demonstrated using a pure aluminum sample around its melting temperature. When the measurement results were calibrated by a literature value of resistivity at the melting point, our resistivity data around the melting point could be expressed by rliq=24.19+1.306×10−2(T−Tm) μΩ cm over Tm∼1160 K, rsolid=10.77+1.421×10−2(T−Tm) μΩ cm over 700 K∼Tm, and the thermal conductivity as determined by the Wiedemann–Franz–Lorenz law from the resistivity data was given by κliq(T)=94.61+4.41×10−2(T−Tm) W m−1 K−1, κsolid(T)=211.13−7.57×10−2(T−Tm) W m−1 K−1. Both electrical resistivity and thermal conductivity are in close agreement with the literature, confirming the validity of the present technique. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149150
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  • 7
    Electronic Resource
    Electronic Resource
    Erratum: A noncontact measurement technique for the density and thermal expansion coefficient of solid and liquid materials [Rev. Sci. Instrum. 67, 3175 (1996)] (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 2597-2597 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148454
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  • 8
    Electronic Resource
    Electronic Resource
    Noncontact surface tension measurement by drop rotation (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 3572-3575 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Validity of the surface tension measurement technique that was proposed by Elleman et al. was experimentally verified. The technique was based on Brown and Scriven's work on the shape evolution of rotating drops. Molten tin and aluminum drops were levitated in high vacuum by the electrostatic levitator and rotated by applying a rotating magnetic field. This technique offers an alternative technique for those liquids where the drop oscillation technique cannot be used. As a demonstration, the technique was applied to a glass-forming alloy (Zr41.2Ti13.8Cu12.5Ni10.0Be22.5) and its surface tension was measured down to the lower temperature where the drop oscillation technique could not be applied due to its high viscosity. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1388215
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  • 9
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    Thermophysical and elastic properties of Cu50Zr50 and (Cu50Zr50)95Al5 bulk-metallic-glass-forming alloys (2006)
    American Institute of Physics
    Details
    Publication Date: 2006-12-11
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
    Published by American Institute of Physics
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  • 10
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    A noncontact measurement technique for the density and thermal expansion coefficient of solid and liquid materials (1996)
    American Institute of Physics
    Details
    Publication Date: 1996-09-01
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics
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