Ceramics-Silikáty 27, (4) 333 - 341 (1983)

The high-temperature oscillation viscometer constructed by the authors operates at up to 1 700 °C in the viscosity range from 0.1 to 1.5 Pa.s. The viscosity is calculated from the value of the logarithmic decrement obtained by measuring the time intervals of a moving beam using two fixed photodetectors. The output of the measuring device was connected 'on-line' to a programmable minicomputer which processed the measuring data. The bodies used in the viscosity measurements were either cylinders or cylinder with conical ends. The viscometer was tested on aqueous glycerine solutions using equations for movement of a cylindrical body in a viscous medium, whereas for the cylindrical body with conical ends the equation was corrected by calibration in glycerine solutions. The absolute error of the viscosity determinations was less than 3 %­. Viscosity measurements were carried out on melts having the compositions CaSiO₃, CaMgSi₂O₆ and Ca₂₂O₇ in the temperature interval 1 390 to 1630 °C.