Effect of Yttrium Oxide on the Viscosity and Crystallization of Borosilicate Glass at High Temperature

Effect of Y2O3 on the viscosity and Crystallization of of borosilicate glass at high temperature was investigated at high temperature. Melt viscosity as a function of temperature was determined by using a rotating spindle viscometer. Liquidus temperature was determined by the Gradient Furnace Method. The results show that the viscosity decreased as a function of Y2O3 content. The activation energy of glass without Y2O3 is about 110.3 kJ·mol-1 and the activation energy increases with the Y2O3 addition up to the 2 wt%. At 2 wt% Y2O3, the specimen shows the maximum activation energy value of 112.6 kJ·mol-1. As Y2O3 content increase, the activation energy decreases. The fiber-forming temperature of glass without Y2O3 is about 1342 oC and the fiber-forming temperature increases with the Y2O3 addition up to the 2 wt%. At 2 wt% Y2O3, the sample shows the maximum activation energy value of 1370 °C. When Y2O3 content increase, the fiber-forming temperature decreases. The liquidus temperature of glass decreases from 1313 °C to 1023 °C when Y2O3 content increases from 0 wt% to 6 wt%. The difference between the fiber-forming and the liquidus temperatures of glass increases from 30 oC to 336 °C when Y2O3 content increases from 0 wt% to 6 wt%.