Rostislav Dudek

Registration of rheological properties of liquids by electromagnetic levitation

The presented paper is focused on possibilities of research of rheological properties of liquids with use of the device based on the principle of electromagnetic levitation. The device works on the principle of damping of the levitated body vibrations by the liquid. Levitation is ensured by feedback control of the magnetic field using an optical barrier. Vibrations are excited by controlled interruptions of electromagnetic field. Thanks to this principle it is possible to investigate the liquid of non-Newtonian character, as well as liquids susceptible to clinging on spindles of rotational viscometers. The equipment was calibrated using silicate oil standards and its performance was compared with commercially used models of viscometers Anton Paar FRS1600 (viscosity range 3 mPa s–20 Pa s, precision 0.5%, temperature range 300–1600°C) and Brookfield DV-III Ultra (viscosity range 1.4 mPa s–20 Pa s, precision 1%, temperature range 100–1600°C).

Modelling of Surface Properties of Selected Silicate System

Presented paper deals with investigation of selected ternary oxidic system with high content of silicates from the viewpoint of surface properties. Research was focused not only on experimental investigation, but mostly on theoretical modelling of surface tension. This approach was chosen due to absence of compact set of information from the area of heterogeneous processes at high temperatures. It is moreover very often difficult to access appropriate data. Surface propertieswere investigated by sessile drop method. Afterwards calculation was made with use of selected semi-empirical models and obtained outputs were confronted with experimentally obtained data. Modelling comprised also temperature dependence of surface tension and influence of SiO2 on its values.