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Structural relaxation mechanisms in hydrous sodium borosilicate glasses

  • Borosilicate glasses (16Na2O–10B2O3–74SiO2, NBS) with water contents up to 22 mol% H2O were prepared to study the effect of water on structural relaxation using DTA, viscometry and internal friction measurements. The results show that the glass transition temperature Tg of DTA and the isokom temperature T12, of viscometry are in excellent agreement, confirming the equivalence of enthalpy and viscous relaxation for NBS glass. Combining Tg data with water speciation data demonstrates that OH groups are mainly responsible for the decrease of Tg with increasing hydration, while molecular water plays only a minor role. Internal friction spectra at 7.125 Hz confirm the decisive influence of water on mechanical relaxation. The temperature range of α-relaxation (glass transition) strongly decreases while two β-relaxation peaks (sub-Tg) progressively appear with increasing water content. A high temperature β-relaxation peak, attributed to the presence of OH groups, shifts from 670 to 450Borosilicate glasses (16Na2O–10B2O3–74SiO2, NBS) with water contents up to 22 mol% H2O were prepared to study the effect of water on structural relaxation using DTA, viscometry and internal friction measurements. The results show that the glass transition temperature Tg of DTA and the isokom temperature T12, of viscometry are in excellent agreement, confirming the equivalence of enthalpy and viscous relaxation for NBS glass. Combining Tg data with water speciation data demonstrates that OH groups are mainly responsible for the decrease of Tg with increasing hydration, while molecular water plays only a minor role. Internal friction spectra at 7.125 Hz confirm the decisive influence of water on mechanical relaxation. The temperature range of α-relaxation (glass transition) strongly decreases while two β-relaxation peaks (sub-Tg) progressively appear with increasing water content. A high temperature β-relaxation peak, attributed to the presence of OH groups, shifts from 670 to 450 K as total water content increases from 0.01 to 5 wt%. A low temperature β-relaxation peak, attributed to molecular water, appears at 380 K and 330 K in glasses containing 3 and 5 wt% H2O, respectively. These findings suggest that relaxation mechanism of different hydrous species at low temperature may contribute to fatigue of stressed glasses.zeige mehrzeige weniger

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Metadaten
Autoren/innen:H. Behrens, U. Bauer, Stefan Reinsch, P. Kiefer, Ralf Müller, J. Deubener
Dokumenttyp:Zeitschriftenartikel
Veröffentlichungsform:Verlagsliteratur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Journal of Non-Crystalline Solids
Jahr der Erstveröffentlichung:2018
Organisationseinheit der BAM:5 Werkstofftechnik
5 Werkstofftechnik / 5.6 Glas
Verlag:Elsevier B.V.
Jahrgang/Band:497
Erste Seite:30
Letzte Seite:39
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Borosilicate glass; Glass transition; Internal friction; Relaxation; Water
Themenfelder/Aktivitätsfelder der BAM:Material
Material / Degradation von Werkstoffen und Materialien
DOI:https://doi.org/10.1016/j.jnoncrysol.2018.05.025
URL:http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=CCC&DestLinkType=FullRecord;KeyUT=CCC:000438479200005
Verfügbarkeit des Volltexts:Volltext-PDF im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:30.07.2018
Referierte Publikation:Ja
Datum der Eintragung als referierte Publikation:30.07.2018