TY - JOUR A1 - Zietka, S. A1 - Deubener, J. A1 - Behrens, H. A1 - Müller, Ralf T1 - Glass transition and viscosity of hydrated silica glasses JF - European journal of glass science and technology / B N2 - The viscosity of silica glasses with different water contents was measured by penetration of sapphire microspheres in the range from 1012-1014·7 Pas at ambient pressure. Commercial silica glasses were used together with hydrous silica glasses, which were prepared by melting glass powder plus water in an internally heated pressure vessel at 2-3 kbar and 1350-1450°C. The temperature dependence of the viscosity of silica glasses with total water contents Cw of 5·4×10-4, 7·0×10-4, 1·00×10-2, and 1·55×10-2(Cw in mass fractions) can be described by Arrhenius equations. From the results, the linear dependence of the T12 isokom (K) with the logarithm of the water content was determined as T12=192-409 logCw. The analysis of the compositional dependence of the T12 isokom in the H2O-Na2O-SiO2 system reveals a temperature depression of up to 200 K for mixed water- and sodium-bearing glasses compared to H2O-SiO2 and Na2O-SiO2 glasses with same molar silica content. From these findings we conclude that protons may contribute significantly to the mixed alkali effect in glasses. KW - Wassergehalt KW - Silicatgläser KW - Viskosität PY - 2007 SN - 1753-3562 SN - 0017-1050 SN - 0031-9090 SN - 1750-6697 VL - 48 IS - 6 SP - 380 EP - 387 PB - Society of Glass Technology CY - Sheffield AN - OPUS4-18396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Rouxel, T. A1 - Behrens, H. A1 - Deubener, J. A1 - Müller, Ralf T1 - Vacuum crack growth in alkali silicate glasses JF - Journal of non-crystalline solids N2 - Crack growth velocity in alkali silicate glasses was measured in vacuum across 10 orders of magnitude with double cantilever beam technique. Measured and literature crack growth data were compared with calculated intrinsic fracture toughness data obtained from Young´s moduli and the theoretical fracture surface energy estimated from chemical bond energies. Data analysis reveals significant deviations from this intrinsic brittle fracture behavior. These deviations do not follow simple compositional trends. Two opposing processes may explain this finding: a decrease in the apparent fracture surface energy due to stress-induced chemical changes at the crack tip and its increase due to energy dissipation during fracture. KW - Silicate glass KW - Brittle fracture KW - Crack growth KW - Calculated intrinsic fracture toughness PY - 2021 DO - https://doi.org/10.1016/j.jnoncrysol.2021.121094 SN - 0022-3093 VL - 572 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-53144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Waurischk, Tina A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Kiefer, P. A1 - Deubener, J. A1 - Balzer, R. A1 - Behrens, H. T1 - Crack Growth in Hydrous Soda-Lime Silicate Glass JF - Frontiers in Materials N2 - Stable crack growth was measured for nominal dry and water-bearing (6 wt%) soda-lime silicate glasses in double cantilever beam geometry and combined with DMA studies on the effects of dissolved water on internal friction and glass transition, respectively. In vacuum, a decreased slope of logarithmic crack growth velocity versus stress intensity factor is evident for the hydrous glass in line with an increase of b-relaxation intensity indicating more energy Dissipation during fracture. Further, inert crack growth in hydrous glass is found to be divided into sections of different slope, which indicates different water related crack propagation mechanism. In ambient air, a largely extended region II is observed for the hydrous glass, which indicates that crack growth is more sensitive to ambient water. KW - Internal friction KW - Soda-lime silicate glass KW - Water content KW - Stable crack growth KW - DCB geometry KW - Stress intensity factor PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506829 DO - https://doi.org/10.3389/fmats.2020.00066 VL - 7 SP - Articel 66 AN - OPUS4-50682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Reinsch, Stefan A1 - Schadrack, Reinhard A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. T1 - Bestimmung der Glastransformationstemperatur wasserhaltiger Gläser T2 - Programm und Referate - 80. Glastechnische Tagung T2 - 80. Glastechnische Tagung CY - Dresden, Deutschland DA - 2006-06-12 PY - 2006 SN - 3-921089-46-8 SP - 1(?) EP - 5(?) PB - Verl. d. Dt. Glastechn. Ges. CY - Offenbach AN - OPUS4-12552 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinsch, Stefan A1 - Rössler, C. A1 - Bauer, Ute A1 - Müller, Ralf A1 - Deubener, J. A1 - Behrens, H. T1 - Water, the other network modifier in borate glasses JF - Journal of non-crystalline solids N2 - In the present study we have investigated whether the effect of water on properties of borate glasses resembles that of alkali oxide. Soda-lime-borate glasses with nominal compositions of x Na2O, 10 CaO, (90-x) B2O3 (x = 5, 15 and 25 mol%) were doped with up to 8 wt.% H2O by processing glass powder + distilled water in platinum capsules in an internally heated gas pressure vessel at 1523 K and 500 MPa. The water content of hydrous glasses was determined by Karl-Fischer titration and near-infrared spectroscopy. The glass transition temperature T-g. was derived from DTA and micropenetration experiments for which the effect of water loss at the surface of the hydrous glasses was studied. Heating glass samples at 10 K min(-1) in the DTA resulted in T-g values which are close to T-12 isokom temperatures confirming the equivalence of enthalpy relaxation and viscous relaxation for borate glasses. For all three glass series it is shown that T-g strongly decreases whereas the liquid fragility strongly increases upon the addition of water. These findings reveal that H2O primarily causes breaking of B-O-B bonds rather than supporting 4-fold coordinated boron as it is well-known for alkali oxides in this concentration range. (C) 2015 Elsevier B.V. All rights reserved. KW - Wasserhaltige Gläser KW - Viskosität KW - Boratgläser KW - Thermische Analyse KW - Viscosity KW - Borate glasses KW - Thermal analysis KW - Water-bearing glasses PY - 2016 DO - https://doi.org/10.1016/j.jnoncrysol.2015.10.010 SN - 0022-3093 VL - 432 SP - 208 EP - 217 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Deubener, J. A1 - Behrens, H. T1 - Internal friction of hydrated soda-lime-silicate glasses JF - The journal of chemical physics N2 - The internal friction of hydrated soda-lime-silica glasses with total water content (CW ) up to 1.9 wt. % was studied by dynamic mechanical analysis (DMA) using temperature-frequency sweeps from 723 K to 273 K and from 1 s-1 to 50 s-1. Total water content and concentrations of H2O molecules (CH2O ) and OH groups (COH) in the DMA specimens were determined by infrared spectroscopy. For low water contents (CW ≈ COH < 0.25 wt. %) two discrete internal friction peaks below the glass transition (α relaxation) were assigned to the low-temperature motion of alkali ions (γ relaxation) and cooperative movements of dissimilar mobile species under participation of OH at higher temperature (βOH relaxation). For large water contents (CW > 1 wt. %), where significant amounts of molecular water are evident (CH2O > 0.15 wt. %), however, internal friction spectra change unexpectedly: the βOH peak heights saturate and a low temperature shoulder appears on the β-relaxation peak. This emerging relaxation mode (βH2O relaxation) was assigned to the motions of H2O molecules. βH2O relaxation was found to be faster than βOH but slower than γ relaxation. Activation energy of the different relaxation modes increased in the order γ < βH2O < βOH < α. KW - Internal friction KW - Glass KW - Water content PY - 2013 DO - https://doi.org/10.1063/1.4828740 SN - 0021-9606 SN - 1089-7690 VL - 139 SP - 174506-1 EP - 174506-6 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-29698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Ralf A1 - Waurischk, Tina A1 - Behrens, H. A1 - Deubener, J. T1 - Crack growth in borate and silicate glasses: Stress-corrosion susceptibility and hydrolytic resistance JF - Journal of Non-Crystalline Solids N2 - A double cantilever beam technique in air equipped with ultrasound modulation was used to measure the crack velocity v in borate and silicate glasses. In all glasses v and the stress intensity KI followed the empirical correlation v ~ KIn. Indicated by its smallest KI at v = 1 μm s − 1, KI* = 0.27 MPa m0.5, the silicoborate glass containing 70 mol% B2O3 was found most susceptible to stress-corrosion enhanced crack growth. Contrarily, the sodium calcium magnesium silicate glass appeared least susceptible with KI* = 0.57 MPa m0.5. No clear correlation is evident between KI*, reflecting the stress-corrosion susceptibility, and the hydrolytic resistance for all glasses under study, but values of n obtained from the present study and taken from previous literature for 35 glasses tend to decrease with increasing network modifier ion fraction. Energy dissipation during stress-corrosion enhanced crack propagation is assumed to cause this trend. KW - DCB KW - Alkali and alkaline earth silicate and borate glass KW - Crack growth in air KW - Stress-corrosion KW - Stress intensity PY - 2021 DO - https://doi.org/10.1016/j.jnoncrysol.2020.120414 VL - 551 SP - 120414 PB - Elsevier B.V. AN - OPUS4-51393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. T1 - Impact of structure and relaxation on fatigue and micromechanical properties of oxide glasses: the role of volatiles and bonding state N2 - As subcritical crack growth (SCCG) can reduce tensile strength of glasses by many orders of magnitude, the potential for improvement of fatigue behaviour is most intriguing in developing ultra-strong glasses. An essential bottleneck is the basic understanding of the numerous interplaying pressure-, temperature- and water-affected relaxation phenomena at the crack tip and related toughening strategies. Therefore, the present project aims to advance the basic understanding of structural relaxation effects and local properties caused by increased water concentration and tensile stresses at the crack tip as they are a key for structural toughening designs to develop SCCG-free glasses and glass surfaces. Our first studies give clear evidence that glass structure and dynamics is strongly modified upon hydration of glasses. These changes are highly related to the nature of network formers but are affected as well by the counter ions (network modifier). Results of the 1st project part suggest that structural relaxation below glass transition temperature, i.e. overlapping of short-range (beta) and long-range (alpha) interactions can contribute to SCCG in water-free environments and that structurally dissolved water in the glasses can have decisive impact on this effect. In the 2nd project stage specific glasses compositions will be investigated to gain an improved understanding on the relation of sub-Tg relaxation and inert SCCG as well as to shed light to the related effects of dissolved water and its speciation. These glasses cover a broader range of different glass topologies and binding partners, whereby the coupling of alpha and beta relaxations is varied systematically by alkali-, alkaline earth ions and water species concentrations. Preparation of hydrous glasses (up to 8 wt% water) will be performed by high pressure syntheses. Structure will be resolved by NMR, Raman and IR spectroscopy while structural relaxation is accessed in the temperature and frequency domain using dynamic mechanical spectroscopy and ultrasonic damping. We will focus on measurements of inert SCCG (region III) conducting experiments in vacuum and dry gas atmospheres using indentation techniques and stressing of glass specimens in DCB geometry. Experimental data on SCCG will be provided to SPP groups, which deals with fatigue in metallic glasses and vice versa we will test theoretical predictions of ab-initio simulations of partner within SPP 1594 in order to quantify the effect of water on the crack tip. In summa topological factors controlling the subcritical crack growth with respect to water will be identified from which structural toughening designs for highly fatigue resistant-glasses can be derived. N2 - Subkritisches Risswachstum (SCCG) kann die Zugfestigkeit von Glas um viele Größenordnungen erniedrigen. Deshalb birgt die Verbesserung des Ermüdungsverhaltens ein hohes Potential für das topologische Design hochfester Gläser. Ein diesbezüglicher Engpass ist das Verständnis der zahlreichen interagierenden druck-, temperatur- und wasserbeeinflussten Relaxationsphänomene an der Rissspitze und hieraus abgeleitete Verstärkungsstrategien. Ziel des Projekts ist es daher, das grundlegende Verständnis der Effekte, die infolge erhöhter Wasserkonzentrationen und Zugspannungen an der Rissspitze entstehen, zu vertiefen, da sie als ein Schlüssel für künftige strukturelle Designprinzipien zur Entwicklung schadenstoleranter Gläser und Glasoberflächen gelten. Unsere ersten Studien zeigen, dass die Struktur und Dynamik von Gläsern nach einer Hydration stark verändert sind. Diese Modifikationen sind mit der Art der Netzwerkbildner stark verknüpft, aber auch von ihren Gegenionen (Netzwerkwandler) abhängig. Die Ergebnisse des ersten Projektabschnitts legen nahe, dass strukturelle Relaxation unterhalb der Glasübergangstemperatur, d. h. ein Überlappen von kurz-reichweitigen (beta) und lang-reichweitigen (alpha) Wechselwirkungen, zum subkritisches Risswachstum in wasserfreien Umgebungen beitragen kann und, dass strukturell gelöstes Wasser in Gläsern sich entscheidend auf diese Effekt auswirken kann. Im zweiten Projektabschnitt werden daher spezielle Glaszusammensetzungen untersucht, die zu einem besseren Verständnis der Verbindung zwischen sub-Tg Relaxation und SCCG führen aber auch den Einfluss von gelöstem Wasser und dessen Speziation näher beleuchten. Diese Gläser weisen eine großen Breite an verschiedenen Topologien und Bindungspartnern auf, wobei die Kopplung von alpha und beta Relaxation durch Veränderungen in den Gehalten von Alkali-, Erdalkalionen und der Wasserspezies systematisch variiert wird. Die Präparation hydratisierter Gläser (bis zu 8 Ma.%) erfolgt mittels Hochdrucksynthesen. Die Glasstruktur wird durch NMR, Raman und IR Spektroskopie aufgeklärt während die Strukturrelaxation anhand dynamische mechanische Spektroskopie und Ultraschalldämpfung im Temperatur- und Frequenzraum erfasst wird. Im Fokus werden Messungen des inerten subkritischen Risswachstums (Region III) stehen, die Indenter-Experimente im Vakuum und trockenen Gasatmosphären sowie Verspannen von Glasproben in DCB Geometrie beinhalten. Experimentelle SCCG Daten werden Gruppen im Schwerpunktprogramm zur Verfügung stellen, die sich mit Ermüdung in metallischen Gläsern beschäftigen und im Gegenzug werden wir theoretische Vorhersagen aus ab initio Simulationen der Partner im SPP 1594 testen, um den Einfluss von Wasser auf die mechanischen Eigenschaften an der Rissspitze und deren Einfluss auf SCCG zu quantifizieren. In summa werden topologische Faktoren bezüglich Wasser, die SCCG kontrollieren, identifiziert, um daraus Designprinzipien für hoch ermüdungsresistente Gläser abzuleiten. T2 - Kolloquium des DFG-PP 1594 CY - Jena, Germany DA - 17.9.2015 KW - Glass KW - Fatigue PY - 2015 AN - OPUS4-38334 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. A1 - Reinsch, Stefan A1 - Bauer, Ute A1 - Rößler, C. T1 - Impact of structure and relaxation on fatigue and micro-mechanical properties of oxide glasses: the role of volatiles and bonding state N2 - As subcritical crack growth (SCCG) can reduce tensile strength of glasses by many orders of magni-tude, the potential for improvement of fatigue behaviour is most intriguing in developing ultra-strong glasses. An essential bottleneck is the basic understanding of the numerous interplaying pressure-, temperature- and water-affected relaxation phenomena at the crack tip and related toughening strat-egies. Therefore, the present project aims to advance the basic understanding of structural relaxa-tion effects and local properties caused by increased water concentration and tensile stresses at the crack tip as they are a key for structural toughening designs to develop SCCG-free glasses and glass surfaces. Our first studies give clear evidence that glass structure and dynamics is strongly modified upon hy-dration of glasses. These changes are highly related to the nature of network formers but are affect-ed as well by the counter ions (network modifier). Results of the 1st project part suggest that struc-tural relaxation below glass transition temperature, i.e. overlapping of short-range (beta) and long-range (alpha) interactions can contribute to SCCG in water-free environments and that structurally dissolved water in the glasses can have decisive impact on this effect. In the 2nd project stage specific glasses compositions will be investigated to gain an improved un-derstanding on the relation of sub-Tg relaxation and inert SCCG as well as to shed light to the relat-ed effects of dissolved water and its speciation. These glasses cover a broader range of different glass topologies and binding partners, whereby the coupling of alpha and beta relaxations is varied systematically by alkali-, alkaline earth ions and water species concentrations. Preparation of hy-drous glasses (up to 8 wt% water) will be performed by high pressure syntheses. Structure will be resolved by NMR, Raman and IR spectroscopy while structural relaxation is accessed in the temper-ature and frequency domain using dynamic mechanical spectroscopy and ultrasonic damping. We will focus on measurements of inert SCCG (region III) conducting experiments in vacuum and dry gas atmospheres using indentation techniques and stressing of glass specimens in DCB geometry. Experimental data on SCCG will be provided to SPP groups, which deals with fatigue in metallic glasses and vice versa we will test theoretical predictions of ab-initio simulations of partner within SPP 1594 in order to quantify the effect of water on the crack tip. In summa topological factors con-trolling the subcritical crack growth with respect to water will be identified from which structural toughening designs for highly fatigue resistant-glasses can be derived. T2 - Kolloquium des DFG-PP 1593 Ultrastrong Glasses CY - Jena, Germany DA - 17.9.2015 KW - Glass KW - Fatigue PY - 2015 AN - OPUS4-38335 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kiefer, P. A1 - Maiwald, M. A1 - Deubener, J. A1 - Balzer, R. A1 - Behrens, H. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Automated Analysis of Slow Crack Growth in Hydrous Soda-Lime Silicate Glasses JF - Frontiers in Materials N2 - To explore the impact of ambient and structural water on static fatigue, the initiation and growth of 3279 Vickers induced median radial cracks were automatically recorded and analyzed. We find that humidity is more efficient in initiating cracks and promoting their growth than water, which is dissolved in the glass structure. In particular for slow crack growth (< 3x10-6 m s-1), tests in dry nitrogen showed a considerable decrease in the crack growth exponent with increasing water content of the glasses. On the other hand, if tests were performed in humid air, the crack growth exponent was independent of the water content of the hydrous glasses, while stress intensity decreased slightly. These observations indicate that water promotes the processes at the crack-tip regardless of its origin. However, ambient water is more efficient. KW - Indentation fracture toughness KW - Slow crack growth KW - Automated analysis KW - Hydrous glass KW - Vickers indentation PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513085 DO - https://doi.org/10.3389/fmats.2020.00268 VL - 7 SP - 268 AN - OPUS4-51308 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -