Effect of composition and structural factors on the viscosity of borosilicate glasses and melts

Abstract

on the temperature curve of the viscosity in the 10 10 -10 4 Pa × sec range were established. The important effect of phase separation processes -liquation and crystallizationon the viscosity indexes in the temperature region of the transition from the plastic to the liquid state was demonstrated.

Effect of B2O3/SiO2 molar ratio and B2O3 content on viscosity and structure of B2O3–SiO2–Al2O3–Na2O–TiO2 glass lubricant

“…In the past, the viscosity and structure relationships of B 2 O 3 -SiO 2 -based melts were investigated. [19][20][21][22][23][24][25] Shiraishi et al 20 found that the viscosity of Na 2 O-B 2 O 3 -SiO 2 (NBS) glass with SiO 2 /Na 2 O molar ratio of 1 or 2 first increased and then showed a decreased trend when B 2 O 3 content increased from 10 to 60 mol.% in the temperature range of 500-650 • C. This is due to the variations in amount of [BO 4 ] and [BO 3 ] in the glass melt. Zhang and Reddy 22 developed a viscosity model based on the melt structure to predict the NBS glass viscosity in the temperature range of 700-1200 • C. The model predictions were in good agreement with experimental data.…”

“…Furthermore, boron anomalies, which were an abnormal change in the boron coordination structure with an increased B 2 O 3 content, were observed when SiO 2 /Na 2 O molar ratio was larger than 1. Mlima and Monteiro 21 and Levitskii and Papko 23 investigated the viscosity of NBS-based glass melt in the temperature range of 600-950 • C. It was found that the phase separation phenomenon between liquid and crystalline phases occurred in the melt, which increased its viscosity by 1-2 magnitudes. Ke et al 24 investigated the effect of alkali oxides on the structure and viscosity of xR 2 O (R represents Na and K)-1.1CaO-12.2B 2 O 3 -(83.7 − x)SiO 2 glass in the temperature range of 1100-1550 • C. It was found that the increased amount of Si-O-B bond leads to a high degree of melt interconnectivity and also improved the chemical stability of the melt when Na 2 O was less than 4 mol.%.…”

“…This affects the smooth running of the extrusion process and the product surface quality after extrusion. In the past, the viscosity and structure relationships of B 2 O 3 –SiO 2 ‐based melts were investigated 19–25 . Shiraishi et al 20 .…”

“…Furthermore, boron anomalies, which were an abnormal change in the boron coordination structure with an increased B 2 O 3 content, were observed when SiO 2 /Na 2 O molar ratio was larger than 1. Mlima and Monteiro 21 and Levitskii and Papko 23 investigated the viscosity of NBS‐based glass melt in the temperature range of 600–950°C. It was found that the phase separation phenomenon between liquid and crystalline phases occurred in the melt, which increased its viscosity by 1–2 magnitudes.…”

Features of the production of glasses for claddings of rigid multimode optical fiber

“…19 that the liquation phase separation that develops in the process of heat treatment of glasses with an increased B 2 O 3 concentration results in an increase of the viscosity indices in the 10 9 -10 4 Pa sec range.…”