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Effect of water on structure and dynamics of sodium borosilicate glasses

  • Borosilicate glass has a wide range of technical applications due to its high chemical durability and thermal-shock resistivity. Here the effect of H2O on 16 Na2O, 10 B2O3,74 SiO2 glass is studied over a wide range of water contents from 0 to 8 wt.%. MIR spectra give evidence for the coexistence of strongly and weakly H-bonded hydrous species. Evaluation of NIR bands at 5200 cm-1 (molecular H2O), 4700 cm-1 (B-OH), and 4500 cm-1 (Si-OH) reveal that OH groups dominate up to ~6 wt.% H2O, with B-OH/Si-OH of ≈ 0.8. The incorporation of low amounts of H2O has strong impact on structure. NMR spectra of nominally dry glasses indicate a significant fraction (12 %) of 3-coordinated boron, but almost all boron is 4-coordinated after addition of 3 wt.% H2O. Raman spectra show that hydration results preferentially in transformation of Q4 to Q2 while Q3 remain unchanged, probably stabilized by bonding to BO4 tetrahedra. Viscosity measurements and differential thermal analysis give consistentBorosilicate glass has a wide range of technical applications due to its high chemical durability and thermal-shock resistivity. Here the effect of H2O on 16 Na2O, 10 B2O3,74 SiO2 glass is studied over a wide range of water contents from 0 to 8 wt.%. MIR spectra give evidence for the coexistence of strongly and weakly H-bonded hydrous species. Evaluation of NIR bands at 5200 cm-1 (molecular H2O), 4700 cm-1 (B-OH), and 4500 cm-1 (Si-OH) reveal that OH groups dominate up to ~6 wt.% H2O, with B-OH/Si-OH of ≈ 0.8. The incorporation of low amounts of H2O has strong impact on structure. NMR spectra of nominally dry glasses indicate a significant fraction (12 %) of 3-coordinated boron, but almost all boron is 4-coordinated after addition of 3 wt.% H2O. Raman spectra show that hydration results preferentially in transformation of Q4 to Q2 while Q3 remain unchanged, probably stabilized by bonding to BO4 tetrahedra. Viscosity measurements and differential thermal analysis give consistent results, confirming strong decrease of the glass transition temperature with addition of water from 849 K (dry) to 540 K (5 wt% H2O). An additional relaxation mechanism in hydrous glasses is inferred from dynamic mechanical analysis and is assigned to cooperative processes involving hydrous species. It is postulated that this relaxation mechanism plays an important role in crack growth kinetics.zeige mehrzeige weniger

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  • Behrens GOMD Hawaii 24-05-17.pdf
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Metadaten
Autor*innen:H. Behrens
Koautor*innen:Ute Bauer, Stefan Reinsch, Ralf Müller, E. I. Morin, J. F. Stebbins, P. Kiefer, J. Deubener
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Borosilicate glass; High water bearing glass; Sub-Tg relaxation; Water speciation
Veranstaltung:12th Pacific Rim Conference on Ceramic and Glass Technology including Glass & Optical Materials Division Meeting
Veranstaltungsort:Waikoloa, USA
Beginndatum der Veranstaltung:21.05.2017
Enddatum der Veranstaltung:26.05.2017
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:05.03.2018
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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