TY - JOUR A1 - Blaeß, Carsten A1 - Müller, Ralf T1 - Master curve for viscous crack healing N2 - A novel method to generalize kinetic data of viscous crack healing in glasses is proposed. The method assumes that crack healing progress is proportional to the healing time, t, and indirect proportional to viscosity, n. This way, crack length and crack width data, normalized to the initial crack length and plotted versus t/n, allow to compare crack healing progress for different cracks and healing temperatures in a master curve. Crack healing experiments conducted in this study demonstrate the applicability of this method for a commercial microscope slide glass. KW - Crack healing KW - Glass KW - Master curve KW - Vickers indentation PY - 2018 U6 - https://doi.org/10.1016/j.matlet.2017.12.082 SN - 0167-577X SN - 1873-4979 VL - 216 SP - 110 EP - 112 PB - Elsevier AN - OPUS4-44300 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wisniewski, W. A1 - Thieme, C. A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Groß-Barsnick, S.-M. A1 - Rüssel, C. T1 - Oriented surface nucleation and crystal growth in a 18BaO·22CaO·60SiO2 mol% glass used for SOFC seals N2 - A glass of the composition 37BaO·16CaO·47SiO2 wt% produced on an industrial scale is crystallized at 970 °C for times ranging from 15 min to 2 h. The crystallization at the immediate surface as well as the crystal growth into the bulk are analyzed using scanning electron microscopy (SEM) including energy dispersive X-ray spectroscopy (EDXS) and electron backscatter diffraction (EBSD) as well as X-ray diffraction in the Θ–2Θ setup (XRD). The immediate surface shows the oriented nucleation of walstromite as well as the formation of wollastonite and an unknown phase of the composition BaCaSi3O8. All three phases also grow into the bulk where walstromite ultimately dominates the kinetic selection and grows throughout the bulk due to a lack of bulk nucleation. Walstromite shows systematic orientation changes as well as twinning during growth. A critical analysis of the XRD-patterns acquired from various crystallized samples indicates that their evaluation is problematic and that phases detected by XRD in this system should be verified by another method such as EDXS. KW - Glass KW - Surface nucleation KW - Orientation KW - EBSD PY - 2018 U6 - https://doi.org/10.1039/c7ce02008b VL - 20 IS - 6 SP - 787 EP - 795 PB - Royal Society of Chemistry AN - OPUS4-44405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Gaber, M. A1 - Reinsch, Stefan T1 - Thermal Analysis and Relaxation Phenomena in Oxide Glasses N2 - Wasser beeinflusst empfindlich eine Vielzahl von thermisch aktivierten Relaxationsphänomenen in Gläsern wie die Spannungsrelaxation, das unterkritische Risswachstum, innere Reibung, Viskosität, Sinterverhalten und Kristallisation. Thermische Methoden können dabei wesentliche Beiträge zum Verständnis dieser Phänomene liefern. Der Vortrag gibt einen Überblick über die Möglichkeiten der VakuumHeißExtraktion (VHE) zur Untersuchung des Wassergehalts, des Wasserabgabeverhaltens und der Wassermobilität sowie über den Einfluss des Wassers auf die innere Reibung (DMA). N2 - Dissolved water decisively influences numerous thermally activated relaxation phenomena in glasses like stress relaxation, sub-critical crack growth, internal friction, viscosity, sintering, and crystallization. Thermoanalytical methods can essentially help for better understanding of these phenomena. The lecture introduces the Vacuum Hot Extraction method (VHE) and illustrates its possibilities for measuring water content, degassing and mobility. As another thermoanalytical method, the Dynamic Mechanical Themoanalysis (DMA), allowing to study the effect of dissolved water on the internal friction in glasses, is introduced. T2 - Spring school DFG SPP 1594 CY - Hannover, Germany DA - 06.03.2018 KW - Wasser KW - Silicatglas KW - Relaxationsphänomene KW - Relaxation KW - Thermoanalytical Methods KW - Glass KW - Dissolved water PY - 2018 AN - OPUS4-45668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Deubener, J. A1 - Behrens, H. T1 - Wasser in Silicatglas N2 - Der Vortrag gibt einen Überblick über den Stand des Wissens zum strukturellen Einbau von Wasser in Silicat- und Boratgläsern, den Einfluss des gelösten Wassers auf deren Viskosität sowie zu den strukturellen Vorstellungen zum Wassertransport. T2 - 1. Fachsymposium der Glasapparatebauer CY - Munich, Germany DA - 19.04.2018 KW - Wasser KW - Glass KW - Struktur PY - 2018 AN - OPUS4-45669 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Glass Sintering with Concurrent Crystallization and Foaming N2 - Glass powders are promising candidates for manufacturing a broad diversity of sintered materials like sintered glass-ceramics, glass matrix composites or glass bonded ceramics with tailored mechanical, thermal, electrical and optical properties and complex shape. Its wide and precise adjustability makes this class of materials a key component for advanced technologies. Processing of glass or composite powders often allow even more flexibility in materials design. At the same time, however, processing can have substantial effects on the glass powder surface and sinterability. Thus, mechanical damage and surface contamination can strongly enhance surface crystallization, which may retard or even fully prevent densification. Whereas sintering and concurrent crystallization have been widely studied, partially as cooperative effort of the TC7 of the ICG, and although glass powder sintering is predominantly applied for glasses of low crystallization tendency, sintering is also limited by gas bubble formation or foaming. The latter phenomenon is much less understood and can occur even for slow crystallizing glass powders. The lecture illustrates possible consequences of glass powder processing on glass sintering, crystallization and foaming. T2 - 7th Int Congress on Ceramics, Symposium Frontiers of Glass Science CY - Iguacu, Brazil DA - 17.06.2018 KW - Glass KW - Powder KW - Sintering KW - Foaming PY - 2018 AN - OPUS4-45670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina A1 - Balzer, R. A1 - Kiefer, P. A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Behrens, H. A1 - Deubener, J. T1 - Sub-critical crack growth in silicate glasses N2 - Environmental conditions are known to influence sub-critical crack growth (SCCG) that are released from microscopic flaws at the glass surface, leading to stress corrosion phenomena at the crack tip. The processes at the crack-tip are complex and water has been identified as a key component governing SCCG at low crack velocities (region I). In particular, the influence of humidity accelerating crack propagation is well studied for industrial soda-lime silicate glasses, which are practically free (< 1000 ppm) of dissolved water. To shed light on the corrosion process, the situation at the crack-tip is reversed in the present study as dissolved water in larger fractions is present in the glass and crack propagation is triggered in dry environment. For this purpose, water-bearing silicate glasses of up to 8 wt% total water were synthesized in an internally heated pressure vessel at 0.5 GPa and compared to dry glasses of standard glass manufacturing. SCCG was measured using the double cantilever beam technique and by Vickers indentation. For dry glasses, three trends in the crack growth velocity versus stress intensity curve were found. The slope in region I limited by environmental corrosion increases in the order sodium aluminosilicate < sodium borosilicate ≲ sodium lead silicate. The velocity range of region II reflecting the transition between corrosion affected and inert crack growth (region III), varies within one order of magnitude among the glasses. The KI region of inert crack growth strongly scatters between 0.4 and 0.9 MPam1/2. For hydrous glasses, it is found that those of low Tg are more prone to SCCG. As water strongly decreases Tg, it promotes SCCG. First results indicate that molecular water has a dominating influence on SCCG. T2 - ICG Annual Meeting 2018 CY - Yokohama, Japan DA - 23.09.2018 KW - DCB KW - Glass KW - Crack growth KW - Water speciation PY - 2018 AN - OPUS4-47164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Agea Blanco, Boris A1 - Blaeß, Carsten A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Behrens, H. T1 - Sintering and foaming of silicate N2 - Glass powders are promising candidates for manufacturing a broad diversity of sintered materials like sintered glass-ceramics, glass matrix composites or glass bonded ceramics with properties and complex shape. Powder processing, however, can substantially affect sinterability, e.g. by promoting surface crystallization. On the other hand, densification can be hindered by gas bubble formation for slow crystallizing glass powders. Against this background, we studied sintering and foaming of silicate glass powders with different crystallization tendency for wet milling and dry milling in air, Ar, N2, and CO2 by means of heating microscopy, DTA, Vacuum Hot Extraction (VHE), SEM, IR spectroscopy, XPS, and ToF-SIMS. In any case, foaming activity increased significantly with progressive milling. For moderately milled glass powders, subsequent storage in air could also promote foaming. Contrarily, foaming could be substantially reduced by milling in water and 10 wt% HCl. Although all powder compacts were uniaxially pressed and sintered in air, foaming was significantly affected by different milling atmosphere and was found most pronounced for milling in CO2 atmosphere. Conformingly, VHE studies revealed that foaming is mainly driven by carbonaceous species, even for powders milled in other gases. Current results of this study thus indicate that foaming is caused by carbonaceous species trapped on the glass powder surface. T2 - ICG Annual Meeting 2018 CY - Yokohama, Japan DA - 23.09.2018 KW - Foaming KW - Glass KW - Powder KW - Sintering PY - 2018 AN - OPUS4-46474 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina A1 - Balzer, R. A1 - Kiefer, P. A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Behrens, H. A1 - Deubener, J. T1 - The influence of volatile constituents on mechanical properties of glasses N2 - Im Rahmen des Young Researcher Day des SPP1594 wurden die bisherigen Inhalte der Projekte zusammengefasst und vorgetragen. T2 - Annual Meeting and Young Researcher Day CY - Jena, Germany DA - 11.09.2018 KW - Glass KW - Crack growth KW - Vickers KW - DCB KW - Water speciation PY - 2018 AN - OPUS4-46728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tielemann, Christopher A1 - Kirzdörfer, Adrian A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - First hints on reorientation of surface crystals N2 - Up to now, the mechanisms of surface nucleation and surface-induced texture formation are far from being understood. Very few observations of crystal orientation were focused on separately growing surface crystals. In conclusion, no systematic studies on initially oriented crystal growth or nucleation from defined active surface nucleation sites exists. Therefore, the main objective of this just is to advance the basic understanding of the mechanisms of surface-induced microstructure formation in glass ceramics. As a first attempt, we focus on reorientation of separately growing surface crystals during their early growth. T2 - 92nd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meetings of the Czech Glass Society & the Slovak Glass Society CY - Bayreuth, Germany DA - 28. Mai 2018 KW - Glass KW - Crystallization KW - BCS PY - 2018 AN - OPUS4-47536 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Tielemann, Christopher A1 - Busch, R. A1 - Patzig, C. A1 - Müller, Ralf A1 - Höche, T. T1 - Oriented surface crystallization in 18BaO·22CaO·60SiO2 and MgO·CaO·2SiO2 glasses N2 - Up to now, oriented surface crystallization phenomena are discussed controversially, and related studies are restricted to few glasses. The vast majority of previous work does not consider possible effects of surface preparation and surrounding atmosphere. Moreover, very few observations of surface crystal orientation were made on separately grown crystals. The aim of our project is to advance the basic understanding of oriented surface crystallization, e.g. whether preferred orientation of surface crystals results from oriented nucleation or reorientation mechanisms during early crystal growth. In both cases, crystal orientation may reflect the orientation of the glass surface or that of anisotropic active surface nucleation sites. Therefore, we focus on orientation of surface crystals separately growing under controlled conditions. First results on diopside (MgCaSi2O6) and walstromite (BaCa2Si3O9) crystals growing from 18BaO·22CaO·60SiO2 and MgO·CaO·2SiO2 glass surfaces, respectively, indicate that different orientation mechanisms may occur. Neighbored walstromite crystals were found to gradually reorient themselves when they are going to impinge each other during stepwise isothermal treatments (log η = 4,5 Pa*s) of polished glass samples. Nevertheless, no preferred crystal orientation was evident for separate crystals. For diopside crystals growing from polished glass surfaces (1 μm diamond lapping foil), strong preferred orientation was observed for 3.5 to 85 min annealing at 850 °C. Electron Backscatter Diffraction (EBSD) studies showed that the c-axis of surface crystals is oriented parallel to the glass surface and that separated diopside crystals as small as 600 nm are already oriented. Studies on glass surfaces, polished with diamond lapping foils starting from 16 μm down to 1 μm grain, revealed that crystal orientation may scatter arround this preferential orientation and that this scatter progressively decreases with decreasing polishing grain size. T2 - 93rd Annual Meeting of the German Society of Glass Technology (DGG) in conjunction with the French Union for Science and Glass Technology (USTV) Annual Meeting CY - Nuremberg, Germany DA - 13.05.2019 KW - Surface crystallization KW - Orientation KW - Glass KW - Diopside PY - 2019 AN - OPUS4-48198 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -