An oscillating cup viscometer based on Shvidkovskiy algorithm for molten metals

In this paper, an oscillating cup viscometer based on Shvidkovskiy algorithm and time-resolved reflection measurement was described for the molten metals over a broad temperature range up to 1800 K. The viscosity of molten metals was automatically calculated from Shvidkovskiy formulae by obtaining the time period and the logarithmic decrement of the oscillations. The representative viscosity measurements using our homemade viscometer were performed for water at a room temperature and pure aluminum in a temperature range from its melting point to 1300 K. It was found that the obtained viscosity results showed good agreement with the previous reports for both water and aluminum, indicating its reliable viscosity measurement. In addition, the experimental uncertainty of the viscometer was also estimated by analyzing the errors propagation of the input parameters of Shvidkovskiy equation. The results showed that a very low uncertainty of 2.1% for the dynamic viscosity measurement, which attributed from the small errors of the logarithmic decrement and time period with highly accurate time-resolved reflection measurement. Therefore, the developed oscillating cup viscometer would be an effective tool for high temperature viscosity measurement in both basic research and industrial applications.