High-temperature contactless viscosity measurements by the gas–film levitation technique: Application to oxide and metallic glasses

Abstract

In the field of thermophysical characterization of materials at high temperature, a crucial issue is to limit the effect of chemical or physical phenomena occurring at the interface between the sample and the container. Therefore, contactless techniques are well adapted to high-temperature measurements. The gas–film levitation method has recently proved to be applicable to viscosity measurements. Our purpose in this article is to derive viscosity values by the observation of the dynamical response of a perturbed levitating drop. We present here recent improvements in this technique, with particular attention paid to measurement accuracy issues and temperature calibration problems. Viscosity measurements performed on oxide and metallic glasses reveal that a gas–film levitation based viscometer is able to provide measurements with good accuracy (±10%) in a wide viscosity range, from very viscous (up to several kPa s, aperiodic relaxation of the drop) to fluid liquids (a few mPa s, damped oscillation of the drop).