Measurement of surface tension of liquid nickel by the oscillating drop technique

摘要

The oscillating drop technique is a well-established method for the measurement of surface tension. In this work an electromagnetic levitation device is used to measure the surface tension of nickel by means of the oscillating drop technique. An electromagnetic levitation device employs an inhomogeneous radio-frequency electromagnetic field inside a levitation coil to heat and position the specimen. Induced eddy currents heat up the material into the liquid phase and exert a Lorentz force, pushing it towards regions of lower field strength. The levitating specimen is investigated by optical setups to provide a contactless measurement. Investigations of nickel have been carried out by the thermophysics and metalphysics group at TU Graz. The temperature dependence of the surface tension presented in this work is γ(T) = 1864 - 0.35·(T-1728) mN m~(-1) in the temperature range from 1700 K to 2020 K.