Engineering topics
Publications and source records attributed to Rhim, W. K..
New non-contact techniques of measuring electrical conductivity and surface tension are introduced.
Six thermophysical properties of both the solid and liquid zirconium measured using the high-temperature electrostatic levitator at JPL are presented.
Present capability of the High Temperature Electrostatic Levitator (HTESL) at JPL for the containerless materials processing is described. The capability includes the measurements of various thermophysical properties and the studies of undercooling and nucleation phenomena.
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.
Present capability of the High Temperature Electrostatic Levitator (HTESL) at JPL for the containerless materials processing is described. The capability includes the measurements of various thermophysical properties and the studies of undercooling and nucleation phenomena.
Molten aluminum and tin drops were levitated in a high vacuum by controlled electric fields, and they were systematically rotated by applying by a rotating magnetic field.
Five thermophysical properties of molten silicon measured by the High Temperature Electrostatic Levitator (HTESL) at JPL are presented. The properties measured are the density, the constant pressure specific heat capacity, the hemispherical total emissivity, the surface tension and the viscosity.
Six thermophysical properties of both the solid and liquid zirconium measured using the high-temperature electrostatic levitator at JPL are presented. These properties are: density, thermal expansion coeffiecient, constant pressure heat capacity, hemispherical total emissivity, surface tension and viscosity.
Shapes and stability of rotating molten metal drops carrying net surface electric charges are experimentally investigated, and the feasibility of measureing surface tension based on drop rotation is examined.
A non-contact technique of measuring the electrical conductivity (or resistivity) of conducting liquids while they are levitated by the high temperature electrostatic levitator in a high vacuum is reported.
Thermophysical properties of molten germanium such as the density, the thermal expansion coefficient, the hemisphereical total emissivity, the constant pressure specific heat capacity, the surface tension, and the electrical resistivity have been measured using the High Temperature Electrostatic Levitator at JPL.
Thermophysical properties of high temperature molten materials have not been determined accurately because of the experimental problems associated with taking measurements at high temperatures.
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Several thermophysical properties of molten silicon measured by the high-temperature electrostatic levitator at JPL are presented. They are density, constant-pressure specific heat capacity, hemispherical total emissivity, and surface tension. Over the temperature range investigated (1350 less than T(sub m) less than 1825 K), the measured liquid density (in g/cc) can be expressed by a quadratic function, pi(P) = p(sub m) - 1.69 x 10(exp -4)(T - T(sub m)) - 1.75 x 10(exp -7)((T - T(sub m))(exp 2) with T(sub m) and p(sub m) being 1687 K and 2.56 g/cc, respectively. The hemispherical total emissivity of molten silicon at the melting temperature was determined to be 0.18, and the constant-pressure specific heat was evaluated as a function of temperature. The surface tension (in 10(exp -3) N/m) of molten silicon over a similar temperature range can be expressed by sigma(T) = 875 - 0.22( T - T(sub m)).
The specific volumes and viscosities of the Ni-Zr liquid alloys as a function of temperature are determined by employing a digitizing technique and numeric analysis methods applied to the optical images of the electrostatically levitated liquid alloys.
The specific volumes of the Zr(41.2)Ti(3.8)Cu(2.5)Ni(10.0)Be(22.5) alloy as a function of temperature, T, are determined by employing an image digitizing technique and numerical calculation methods applied to the electrostatically levitated spherical alloy. The linear fitting of the volumes of the alloy in the liquid, V(sub l), glass, V(sub g) and crystalline V(sub c), states in the temperature ranges shown in parentheses are V(sub l)(T) = 0.1583 + 8.877 x 10(exp -6) T(cu cm/g) (700-1300 K);V(sub g)(T) = 0.1603 + 5.528 x 10(exp -6) T (400-550 K);V(sub c)(T) = 0.1583 + 6.21 x 10(exp -6)T(400-850 K). The average volume thermal expansion coefficients within the temperature ranges are determined to be 5.32, 3.39. and 3.83 x 10(exp -5) (1/K) for the liquid, glass, and crystalline states, respectively.
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Present capabilities of the High Temperature Electrostatic Levitator (HTSEL) for containerless materials processing are summarized. In studying high temperature materials, this technology utilizes electrostatic forces to isolate a sample material from the container walls in a high vacuum condition.