Viscosity-Temperature Characteristics and Application of High Borosilicate Glass

Abstract

Viscosity-temperature characteristics of high borosilicate glass were investigated in detail by means of rotor viscometer and dilatometer. The neck-down deformation process of glass tube was simulated by Polyflow software, and the simulation was verified by the secondary drawing of glass perform. The results showed that the high temperature viscosity of borosilicate glass is higher compared to that of ordinary optical glass. In the high temperature stage, the fitting curves of VFT, AV, AG and MYEGA models are all in good agreement with the tested curve. However, in the low temperature stage, only viscosity fitted by VFT model is close to the tested value. Based on Navier-Stokes equation, a mathematical model of neck-down deformation of glass tube during secondary drawing is established. It is found that viscosity is the key material intrinsic factor affecting neck-down process of glass tube. The distribution of inner and outer diameters of glass tube along the drawing direction is simulated and analyzed under different feeding and drawing rates. The deviation between the steady-state dimension simulated and that actually drawn is only ±0.06 mm.