Measurements of the Temperature-Dependent Total Hemispherical Emissivity Using an Electrostatic Levitation Facility

Abstract

Among the three fundamental processes of heat transfer (conduction, convection, and radiation), radiation is the most dominant at high temperatures. The total hemispherical emissivity is an important property that determines the amount of heat loss by radiation. Unfortunately, the emissivity, especially its temperature dependence \((\varepsilon (T))\), is unknown for most materials. Here, we demonstrate the feasibility of measuring \(\varepsilon (T)\) using an electrostatic levitation (ESL) technique that allows such measurements to be made on levitated solid and liquid samples in a contamination-free, high-vacuum environment. The \(\varepsilon (T)\) for solid Ni and liquid \(\hbox {Zr}_{60}\hbox {Al}_{10}\hbox {Cu}_{18}\hbox {Ni}_{9}\hbox {Co}_{3}\) from these measurements is consistent with the existing literature data.