Effect of TiO₂ on microphase development during phase separation and crystallization in Na₂O–B₂O₃–SiO₂ glass system

Abstract

This study examines the incorporation of TiO2 into sodium borosilicate glasses and its effect on the formation of glassy and crystalline microphases. Glasses in the composition range: 7Na2O–23B2O3–(70 ‐ X)SiO2–XTiO2 (where X = 0–14.6 mol.% TiO2) which exhibit phase separation were investigated. Raman studies confirm the formation of two different TiO2 coordinations depending on the molar content of TiO2. Thermal properties of glasses are unaffected by TiO2 addition. The domain size of microphase development in TiO2‐containing glass indicates competition between phase separation and crystallization. Enrichment of titanium on the interphase between glassy microphases reduces the mass transfer and consequently limits the growth rate of glassy phases. This competes with the formation of anatase for which a nucleation‐controlled mechanism is proposed.

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

“…Table 3 lists corresponding Raman spectra for different structure units, where Q n represents the Si‐related structural unit and n is the number of BO for each unit. Si–O symmetry vibration corresponds to the peaks in the range of 600–800 cm −130,38 and the stretching vibrations of [SiO 4 ] tetrahedron can be reflected by the peaks in the range of 800–1200 cm −1 25,30,39 . Figure 6A shows the variation of original Raman spectra.…”

“…Si-O symmetry vibration corresponds to the peaks in the range of 600-800 cm −130,38 and the stretching vibrations of [SiO 4 ] tetrahedron can be reflected by the peaks in the range of 800-1200 cm −1 . 25,30,39 Figure 6A shows the variation of original Raman spectra. A similar Raman spectroscopy pattern was observed for samples A1 and A2.…”

“…32 Figure 11D,E shows the four bands Q 0 , Q 1 , Q 2 , and Q 3 obtained by fitted peaks in the range of 800-1200 cm −1 according to the Raman spectral assigned bands. 25,30,33,39,43 Figure 11F shows the variations of the peak area fraction of Q n and the calculated X Si values based on Equations ( 2) and (3) induced by B 2 O 3 content change. The peak area of Q 3 reached a maximum value among the four glasses when B 2 O 3 content was 28.28 mol.% (B1), whereas the peak area of Q 2 was only slightly increased.…”

“…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.…”

“…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 .…”