VISCOSITY MEASUREMENT OF GLASS MELT BY A UNIFORM SPEED PENETRATION VISCOMETER IN THE RANGE OF 10(2)-10(8)-PA-CENTER-DOT-S

A new viscometer, uniform speed penetration viscometer, was constructe d with which the viscosity of glass melts can he measured in the range of 10(2)-10(8) Pa.s, a pin dipped in the melt was penetrated into the melt with a uniform speed and the viscous drag an the pin was measure d. A calibration curve between the viscous drag and viscosity was prep ared using NBS711 glass as a standard material. The viscosity of glass melt can be determined from the measured viscous drag and the calibra tion curve. It was ascertained that the viscosities of lead-silicate g lasses can be measured by this viscometer in the range of 10(2)-10(8) Pa.s, and that they agree well with the Littelton point measured by an other method. The limits of measurement at high and low viscosities we re analyzed and discussed basad on the interface phenomena between the pin and the melt.