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 DO - 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 - Prewitz, M. A1 - Gaber, M. A1 - Müller, Ralf A1 - Marotzke, C. A1 - Holtappels, Kai T1 - Polymer coated glass capillaries and structures for high-pressure hydrogen storage: Permeability and hydrogen tightness N2 - The hydrogen tightness of high-pressure hydrogen storage is a Basic criterion for long-term storage. The H2 permeation coefficients of epoxy resin and a glass lacquer were determined to enable the geometric optimization of a glass capillary storage. It was found that the curing conditions have no significant influence on the H2 permeation coefficient of resin. The H2 permeation coefficient of epoxy resin is only about three orders of Magnitude greater than that of borosilicate glass. This suggests that the initial pressure of 700 bar takes about 2.5 years to be halved in capillary array storage. Therefore, a high-pressure hydrogen storage tank based on glass capillaries is ideally suited for long-term storage in mobile applications. KW - Permeability KW - Glass capillaries KW - Coating KW - Hydrogen storage KW - Long-term calculation KW - Epoxy resin PY - 2018 DO - https://doi.org/10.1016/j.ijhydene.2017.12.092 SN - 0360-3199 VL - 43 IS - 11 SP - 5637 EP - 5644 PB - Elsevier AN - OPUS4-44327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Körner, S. T1 - Dissolution and reprecipitation of silver in sintering silver-glass dispersions N2 - Electric contacts based on silver-glass dispersions are key components in optoelectronic microsystems and control modules for medical, information & communication and energy technology in our networked society. Driven by the complexity of modern production processes and ever shorter time-to-market requirements, the fast and specific development of tailored silver-glass dispersions has become a bottleneck of technology development. Nevertheless, the underlying mechanisms of silver dissolution, transport, and reprecipitation, and the resulting micro structure evolution during firing are poorly understood. The broad literature on the precipitation of colloidal silver particles and the related processes of silver dissolution and diffusion mostly refer to very small volume fractions of silver. Transferring these results to the sintering of glass-containing silver dispersions, is therefore highly questionable. In this case, silver dissolution, electrical contact between silver particles, transport and reprecipitation take place under special conditions. This includes short diffusion lengths (particle size < 10 μm), the presence of three-phase contacts silver - glass - sintering atmosphere, as well as silver reprecipitation at the sintering contacts as the driving force of silver transport. Here, a dynamic balance of the silver concentration can be expected to result from the ratio between silver dissolution and reprecipitation. The aim of the project is to gain basic insight into the mechanisms of dissolution, transport and reprecipitation of silver in sintering silver glass dispersions. In this context, the main focus is on gaining basic knowledge about the dissolution of metallic silver in low melting oxide glasses as the limiting factor of the sintering of silver-glass composites. In particular, we will strive to gain insight into the effect of the oxygen content of the sintering atmosphere, of the oxygen dissolved in the silver particles, of silver oxide on the surface of the silver powder, of the electric contact between the silver particles, as well as the basicity of the glass. Furthermore, we strive for insights into the silver mobility and the silver concentration that can be attained (silver solubility) in oxide glasses with a low melting point. Summing up all these aspects, a closed explanatory model for silver dissolution, transport and reprecipitation during the sintering of glass silver dispersions will be introduced. T2 - DFG Begutachtungskolloquium (PAK 949/1 und PAK 950/1) CY - Bonn, Germany DA - 07.03.2017 KW - Sintering KW - Silver KW - Glass KW - Solubility KW - Reprecipitation PY - 2017 AN - OPUS4-44228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Hochtemperaturlaserprofilometrie (HTLP) N2 - Der Vortrag stellt die an der BAM neu entwickelte Methode der Hochtemperatur-Laserprofilometrie (HTLP) vor und illustriert Anwendungsmöglichkeieten T2 - Seminar Instrumentelle Analytik, Fakultät III Prozesswissenschaften, Lehrstuhl Keramik TU Berlin CY - TU Berlin, Germany DA - 17.2.2017 KW - Sintern KW - Hochtemperaturformerkennung PY - 2017 AN - OPUS4-44210 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Volatile concentration and mobility measured by VHE-MS N2 - Der Vortrag schildert die Funktionsweise und einige ausgewählte Anwendungsmöglichkeieten der Vakuum-Heißextraktion an der BAM. T2 - Seminar Instrumentelle Analytik, Fakultät III Prozesswissenschaften, Lehrstuhl Keramik TU Berlin CY - TU Berlin, Germany DA - 17.2.2017 KW - Gehalt volatiler Spezies KW - Heißextraktion PY - 2017 AN - OPUS4-44212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Agea Blanco, Boris A1 - Meyer, Christian A1 - Müller, Ralf A1 - Günster, Jens T1 - Sand erosion of solar glass: Specific energy uptake, total transmittance, and module efficiency N2 - Surface roughness, R Z , normal transmittance, Τ N , total transmittance, Τ T , and photovoltaic (PV) module efficiency, η S , were measured for commercial solar glass plates and PV test modules identically sandblasted with different loads of quartz sand (200 – 400 μ m), impact inclination angles, and sand particle speed. Measured data are presented versus the specific energy uptake during sand blasting, E (J/m2). Cracks, adhering particles, and scratch ‐ like textures probably caused by plastic flow phenomena could be observed after sand blasting. Their characteristic size was much smaller than that of sand particles. After blasting and subsequent cleaning, the glass surface was still covered with adhering glass particles. These particles, cracks, and scratch ‐ like textures could not be removed by cleaning. For sand blasting with α = 30° inclination angle and E = 30 000 J/m2, normal transmittance, total transmittance, and relative module efficiency decreased by 29%, 2% and ∽ 2%, respectively. This finding indicates that diffusive transmission of light substantially contributes to PV module efficiency and that the module efficiency decrease caused by sand erosion can be better estimated from total than by normal transmittance measurements. KW - Transmittance KW - Efficiency KW - Photovoltaic modules KW - Roughness KW - Sand blasting PY - 2018 DO - https://doi.org/10.1002/er.3930 SN - 1099-114X SN - 0363-907X VL - 42 IS - 3 SP - 1298 EP - 1307 PB - Wiley & Sons, Ltd. AN - OPUS4-44157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Glasig-kristalline Werkstoffe für Schlüsseltechnologien - Prozessbegleitende Prüfung und Simulation N2 - Eigenschaftsprofile und Kennwertstreuungen keramischer und glaskeramischer Komponenten und Bauteile werden durch ihren Herstellungsprozess wesentlich mitbestimmt. Prozessbegleitende Prüf- und Simulationsmethoden gewinnen so wachsenden Einfluss auf die Erschließung neuer Applikationsfelder dieser Werkstoffe. Eine wichtige Rol¬le spielen hierbei oft thermokinetische Prozesse, die u. a. Wärmetransport- und Diffusionsvorgänge, Phasengrenzflächenreaktionen, das rheologische Verhalten heterogener Systeme sowie deren Gefügeevolution beim Sintern umfassen. Ziel des Vortrages ist es, diesen Trend anhand ausgewählter Bei-spiele aus der Arbeit des Fachbereichs Glas der BAM zu illustrieren. T2 - Deutsche Physikalische Gesellschaft, Vortragsreihe Gruppe 60+ der Physiker Berlin - Brandenburg CY - Berlin, Magnushaus, Germany DA - 5.4.17 KW - Prozessbegleitende Prüfung KW - LTCC PY - 2017 AN - OPUS4-44217 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Sintering and foaming of barium silicate glass powders N2 - The manufacture of sintered glasses and glass-ceramics, glass Matrix composites and glass-bounded ceramics or pastes is often affected by gas bubble formation. Against this background, we studied sintering and foaming of barium silicate glass powders used as SOFC sealants using different powder milling scenarios. Sintering was measured by means of heating microscopy backed up by XPD, DTA, Vacuum Hot Extraction (VHE) and optical and electron microscopy. Foaming increased significantly as milling progressed. For moderately milled glass powders, subsequent storage in air could also promote foaming. Although the powder compacts were uniaxially pressed and sintered in air, the milling environment significantly affected foaming. The strength of this effect increased in the order Ar >> N2 < air < CO2. Conformingly, VHE studies revealed that the pores of aerated samples predominantly encapsulated CO2, even for powders milled in Ar and N2. Results of this study thus indicate that foaming is caused by carbonaceous species trapped on the glass powder surface. Foaming could be substantially reduced by milling in water and 10 wt% HCl. T2 - 12th Pacific Rim Conference on Ceramic and Glass Technology CY - Waikoloa, Hawaii, USA DA - 21.5.2017 KW - Sintering KW - Gas bubble formation KW - Foaming PY - 2017 AN - OPUS4-44220 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Körner, S. T1 - Dissolution and reprecipitation of silver in sintering silver-glass dispersions N2 - Electric contacts based on silver-glass dispersions are key components in optoelectronic microsystems and control modules for medical, information & communication and energy technology in our networked society. Driven by the complexity of modern production processes and ever shorter time-to-market requirements, the fast and specific development of tailored silver-glass dispersions has become a bottleneck of technology development. Nevertheless, the underlying mechanisms of silver dissolution, transport, and reprecipitation, and the resulting micro structure evolution during firing are poorly understood. The broad literature on the precipitation of colloidal silver particles and the related processes of silver dissolution and diffusion mostly refer to very small volume fractions of silver. Transferring these results to the sintering of glass-containing silver dispersions, is therefore highly questionable. In this case, silver dissolution, electrical contact between silver particles, transport and reprecipitation take place under special conditions. This includes short diffusion lengths (particle size < 10 μm), the presence of three-phase contacts silver - glass - sintering atmosphere, as well as silver reprecipitation at the sintering contacts as the driving force of silver transport. Here, a dynamic balance of the silver concentration can be expected to result from the ratio between silver dissolution and reprecipitation. The aim of the project is to gain basic insight into the mechanisms of dissolution, transport and reprecipitation of silver in sintering silver glass dispersions. In this context, the main focus is on gaining basic knowledge about the dissolution of metallic silver in low melting oxide glasses as the limiting factor of the sintering of silver-glass composites. In particular, we will strive to gain insight into the effect of the oxygen content of the sintering atmosphere, of the oxygen dissolved in the silver particles, of silver oxide on the surface of the silver powder, of the electric contact between the silver particles, as well as the basicity of the glass. Furthermore, we strive for insights into the silver mobility and the silver concentration that can be attained (silver solubility) in oxide glasses with a low melting point. Summing up all these aspects, a closed explanatory model for silver dissolution, transport and reprecipitation during the sintering of glass silver dispersions will be introduced. T2 - DFG Begutachtungskolloquium (PAK 949/1 und PAK 950/1) CY - Bonn, Germany DA - 07.03.2017 KW - Sintering KW - Silver KW - Glass KW - Solubility KW - Reprecipitation PY - 2017 AN - OPUS4-44227 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wirth, Cynthia A1 - Müller, Ralf A1 - Günster, Jens A1 - Mühler, T. A1 - Görke, R. A1 - Heinrich, J.G. T1 - Submicrometer silica spheres generated by laser fuming N2 - The production of agglomerate-free SiO2 particles exhibiting a monomodal distribution of particle sizes of around 300 nm by means of direct laser fuming of micrometric SiO2 powders has been successfully demonstrated. With a 12 kW cw CO2 laser system, a production rate of up to 1 kilogram powder per hour was achieved. Almost ideal spherical amorphous SiO2 particles in a broad particle size distribution between 10 nm and several 100 nm (d50 ≈ 300 nm) were synthesized. Several observations suggest weak agglomeration forces between the particles. A temperature reduction of 200 °C for sintering powder compacts was observed. KW - Laser KW - SiO2 KW - Nanopowder PY - 2013 DO - https://doi.org/10.4416/JCST2012-00033 SN - 2190-9385 N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 4 IS - 1 SP - 11 EP - 18 PB - Göller CY - Baden-Baden AN - OPUS4-31423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ried, Peter A1 - Gaber, Martin A1 - Müller, Ralf A1 - Deubener, J. T1 - Hydrogen permeability of a barium-aluminoborosilicate glass - A methodical approach N2 - The H2 effusion from H2 saturated glass powders, H2 permeation through the wall of blown glass bulbs, and H2 permeation through the wall of glass capillaries were applied to evaluate the permeability of hydrogen gas in a barium-aluminoborosilicate (BABS) glass. To validate these methods, two commercial glasses (vitreous silica and borosilicate) were used as a reference. Permeation values obtained from the different experiments agreed within a factor of 3 or less. The H2 permeability of BABS glass at temperatures close to ambient was found to be at least 3 orders of magnitude below that of borosilicate and silica glasses. The powder method, which requires minimal sample preparation efforts, turned out to provide easy access to the measurement of H2 permeability of glasses down to P = 3.9 × 10- 21 mol s- 1 Pa- 1 m- 1. KW - Hydrogen gas KW - Permeability KW - Solubility KW - Diffusivity KW - Aluminoborosilicate glass PY - 2014 DO - https://doi.org/10.1016/j.jnoncrysol.2014.04.006 SN - 0022-3093 VL - 394-395 SP - 43 EP - 49 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-30720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fest, Sarah Ute A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Milling, sintering and crystallization of 11BaO-25CaO-64SiO2 glass powder N2 - The crystallization of 11BaO-25CaO-64SiO2 mol% glass powders and related effects of glass powder milling have been studied by X-ray diffraction (XRD), light and scanning electron microscopy (SEM) and differential thermal analysis (DTA). Glass powders were made by ZrO2 crushing with subsequent sieving or sedimentation or alternatively made by milling with agate, corundum and tungsten carbide. Although surface crystallization was detectable during late sintering, all powders fully sintered. Wollastonite was found as primary crystal phase followed by cristobalite and sanbornite precipitation. The latter crystallization steps caused a second DTA-peak for fine powders. DTA-peak temperatures shifted to lower temperature with decreasing particle size in any case. No significant effects of milling materials on DTA-peak temperatures were evident. As an exception, however, milling in agate caused strongly decreased temperatures of the second DTA-peak. This observation can be explained by the progressive mechanical damaging, which results from the required prolonged milling time with agate due to its small materials density, and the fact that diamond made scratches did promote surface crystallization of cristobalite. The present study thus shows that even for glass powders with excellent sinterability, milling can affect microstructure evolution. KW - Glass KW - Crystallization KW - Powder preparation KW - SOFC PY - 2014 UR - http://onlinelibrary.wiley.com/doi/10.1111/ijag.12080/full DO - https://doi.org/10.1111/ijag.12080 SN - 2041-1286 SN - 2041-1294 VL - 5 IS - 3 SP - 236 EP - 247 PB - Wiley-Blackwell CY - Hoboken, NJ [u.a.] AN - OPUS4-30807 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Glaspulver - Processing, Effekte, Möglichkeiten T2 - Festkolloquium der Universität des Saarlandes CY - Saarbrücken, Germany DA - 2013-03-23 PY - 2013 AN - OPUS4-30853 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Glas und Keramik für Schlüsseltechnologien - Prozessbegleitende Prüfung und Simulation T2 - Sommerkolloquium des GHI der RWTH CY - Aachen, Germany DA - 2012-06-21 PY - 2012 AN - OPUS4-30854 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Sintering and Crystallization of Glass Powders (invited) T2 - 3rd GlaCERCo Network-wide Workshop CY - Erlangen, Germany DA - 2014-10-08 PY - 2014 AN - OPUS4-30855 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Rate curve and induction time analysis of heterogeneous crystal nucleation in glass-ceramic systems T2 - 1st Joint Meeting of DGG - ACerS GOMD CY - Aachen, Germany DA - 2014-05-25 PY - 2014 AN - OPUS4-30850 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heunisch, Andreas A1 - Marzok, Ulrich A1 - Münchow, Marco A1 - Müller, Ralf A1 - Rabe, Torsten T1 - In situ characterization of the sintering behavior of LTCC laminates with embedded cavities by high temperature laser profilometry T2 - CICMT 2013 - IMAPS/ACerS 9th International conference and exhibition on ceramic interconnect and ceramic microsystems technologies CY - Orlando, FL, USA DA - 2013-04-23 KW - LTCC multilayer KW - Embedded cavities KW - High temperature laser profilometry KW - Low pressure lamination KW - Micro fluidics PY - 2013 DO - https://doi.org/10.4071/cicmt-tha44 SP - 275 EP - 282 AN - OPUS4-35077 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Sintering and Foaming of Barium and Calcium Silicate Glass Powders T2 - IMAPS/ACerS 11th International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystem Technologies (CICMT 2015) CY - Dresden, Germany DA - 2015-04-20 PY - 2015 AN - OPUS4-35197 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Sintering and foaming of barium and calcium silicate glass powders T2 - Crystallization 2015 CY - Nagaoka, Japan DA - 2015-10-11 PY - 2015 AN - OPUS4-35198 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Behrens, H. A1 - Deubener, J. A1 - Müller, Ralf T1 - Impact of structure and relaxation on fatigue and micro-mechanical properties of oxide glasses: the role of volatiles and bonding state T2 - Kolloquium des DFG SPP1594 Ultrastrong Glasses CY - Jena, Germany DA - 2015-09-17 PY - 2015 AN - OPUS4-35203 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 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 - CHAP A1 - Müller, Ralf A1 - Reinsch, Stefan ED - Bansal, N. P. ED - Boccaccini, A.R. T1 - Viscous-phase silicate processing KW - Viskoses Sintern KW - Oberflächenkeimbildung KW - Glaspulver KW - Sintermodelle KW - Sinterglaskeramik KW - Glasmatrixkomposit PY - 2012 SN - 978-0-470-55344-2 IS - Chapter 3 SP - 75 EP - 144 PB - Wiley AN - OPUS4-27054 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Marzok, Ulrich A1 - Müller, Ralf A1 - Krauhausen, M. A1 - Burgstedt, F. A1 - Brode, W. T1 - Hochtemperatur shape screening keramischer Bauteile KW - Keramikherstellung KW - Sintern KW - Formmessung KW - Kontur KW - Lasermesstechnik PY - 2010 UR - http://edok01.tib.uni-hannover.de/edoks/e01fb12/685831345.pdf IS - Schlussbericht / Az: II D 5 - 25/06 SP - 1 EP - 54 CY - Berlin AN - OPUS4-28373 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Wirth, Cynthia A1 - Bernardo, E. A1 - Müller, Ralf A1 - Günster, Jens A1 - Colombo, P. T1 - LAS glass-ceramic scaffolds by three-dimensional printing N2 - Highly porous (>60% open porosity) glass–ceramic scaffolds with remarkable mechanical properties (compression strength of ~15 MPa) were produced by indirect 3D printing. Precursor glass powders were printed into 3D ordered structures and then heat treated to sinter and develop crystalline phases. The final glass–ceramic contained a β-spodumene solid solution together with a secondary phase of lithium disilicate. The precision of the printed geometry and the density of the struts in the scaffold depended on several processing parameters (e.g. powder size and flowability, layer thickness) and were improved by increasing the binder saturation and drying time. Two types of powders with different particle size distribution (PSD) and flowability were used. Powders with a larger PSD, could be processed within a wider range of printing parameters due to their good flowability; however, the printing precision and the struts density were lower compared to the scaffolds printed using the powder in a smaller average PSD. KW - Glass ceramics KW - Porosity KW - Shaping KW - Strength KW - Additive manufacturing PY - 2013 DO - https://doi.org/10.1016/j.jeurceramsoc.2012.12.012 SN - 0955-2219 SN - 1873-619X N1 - Geburtsname von Wirth, Cynthia: Gomes, C. M. - Birth name of Wirth, Cynthia: Gomes, C. M. VL - 33 IS - 9 SP - 1525 EP - 1533 PB - Elsevier CY - Oxford AN - OPUS4-28284 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winkel, A. A1 - Meszaros, R. A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Travitzky, N. A1 - Fey, T. A1 - Greil, P. A1 - Wondraczek, L. T1 - Sintering of 3D-printed glass/HAp composites N2 - We report the sintering of 3D-printed composites of 13-93 bioactive glass and hydroxyapatite (HAp) powders. The sintering process is characterized on conventionally produced powder compacts with varying HAp content. A numeric approximation of the densification kinetics is then obtained on the basis of Frenkel, Mackenzie–Shuttleworth, and Einstein–Roscoe models, and optimized sintering conditions for 3D-printed structures are derived. Fully isotropic sintering of complex cellular composites is obtained by continuous heating to 750°C at a rate of 2 K/min for a HAp content of 40 wt%. The approach can readily be generalized for printing and sintering of similar glass-ceramic composites. KW - Sintering glass composit bio material PY - 2012 DO - https://doi.org/10.1111/j.1551-2916.2012.05368.x SN - 0002-7820 SN - 1551-2916 VL - 95 IS - 11 SP - 3387 EP - 3393 PB - Blackwell Publishing CY - Malden AN - OPUS4-27053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marzok, Ulrich A1 - Müller, Ralf A1 - Schadrack, Reinhard A1 - Krauhausen, M. A1 - Burgstedt, F. A1 - Brode, W. A1 - Reetz, R. T1 - High-temperature laser profilometry for ceramic tapes N2 - Advanced ceramics are promising key components for microsystems engineering, communication Technology and medical engineering. Driven by steadiiy increasing demands on dimensional accuracy of components and Integration density, sintering has to be controlled at an unprecedented degree of precision. Being most crucial for components of complex shape, graded or heterogeneous-composed parts like LTCC multilayers for microsystems, precise control of sintering has a decisive influence on the dimensional accuracy, mechanical integrity and reliability of sintered components. Thus, permanent or temporary shape distortions or warping during sintering may result from spatially heterogeneous microstructure and temperature distribution, e.g. during the co-firing process of green multilayer Stacks printed with metallization and other functional pastes. Whereas permanent warping can be easily measured after sintering, temporary warping during firing is more difficult to measure. Nonetheless, this effect may cause latent failures later, which often limit the applicability of ceramic components. PY - 2013 SN - 0173-9913 SN - 0196-6219 VL - 90 IS - 4 SP - E35 EP - E40 PB - Göller CY - Baden-Baden AN - OPUS4-28500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Agea Blanco, Boris A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Sintering and foaming of barium silicate glass powder compacts N2 - The manufacture of sintered glasses and glass-ceramics, glass matrix composites, and glass-bounded ceramics or pastes is often affected by gas bubble formation. Against this background, we studied sintering and foaming of barium silicate glass powders used as SOFC sealants using different powder milling procedures. Sintering was measured by means of heating microscopy backed up by XPD, differential thermal analysis, vacuum hot extraction (VHE), and optical and electron microscopy. Foaming increased significantly as milling progressed. For moderately milled glass powders, subsequent storage in air could also promote foaming. Although the powder compacts were uniaxially pressed and sintered in air, the milling atmosphere significantly affected foaming. The strength of this effect increased in the order Ar ≈ N2 < air < CO2. Conformingly, VHE studies revealed that the pores of foamed samples predominantly encapsulated CO2, even for powders milled in Ar and N2. Results of this study thus indicate that foaming is caused by carbonaceous species trapped on the glass powder surface. Foaming could be substantially reduced by milling in water and 10 wt% HCl. KW - Glass powder KW - Sintering KW - Foaming KW - SOFC PY - 2016 UR - http://journal.frontiersin.org/article/10.3389/fmats.2016.00045/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Frontiers_in_Materials&id=214488 DO - https://doi.org/10.3389/fmats.2016.00045 SN - 2296-8016 VL - 3 SP - Article 45, 1 EP - 10 AN - OPUS4-38303 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Sintering and crystallization of glass powders – effects, challenges and chances N2 - Chemical variability is a main strength of glass. Glass powders are therefore 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, even if it may not be obvious at first sight, a key component of advanced technologies. Manufacture and processing of initial glass powders often allow even more flexibility in materials design. At the same time, however, they can cause additional problems. The lecture illustrates possible consequences of glass powder processing upon glass crystallization and sintering as well as chances for targeted utilization. Simple kinetic models describing the effect of particle size distribution, surface crystallization and rigid inclusions on sintering as well effects of different milling and seeding on sinter crystallization are presented. T2 - Institutskolloquium CSIC CY - Madrid, Spain DA - 28.4.2016 KW - Glass KW - Powders KW - Sintering KW - Crystallization KW - SOFC KW - LTCC PY - 2016 AN - OPUS4-38333 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. 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 - CONF A1 - Müller, Ralf T1 - High-temperature laser profilometry N2 - Advanced methods for 3D green density characterization like computed tomography and 3D FE sinter modeling can be utilized for increasing the reliability of sintered components. The experimental in situ observation of sintering, however, is currently restricted to silhouette methods, i.e. heating microscopy. For complex shaped samples, in situ shape screening during shrinkage would allow much better validation of 3D sinter simulation models. Further, by revealing temporary sinter warpage, 3D high-temperature shape screening allows to locate potential defects of complex sintered components. Against this background, BAM developed a testing device for in situ 3D high-temperature shape screening for ceramic and glass-ceramic tapes up to 1000°C [1-3]. Current work is focused on dropping this restriction in sample shape and temperature. The poster illustrates the current state of this work and possible applications of the method e.g. in detecting sinter warpage of metallized glass-ceramic LTCC tapes. T2 - SGT Centenary Conference, & ESG 2016 CY - Sheffield, UK DA - 04. 09. 2016 KW - Laser profilometry KW - 3D High-temperature shape screening KW - Sintering PY - 2016 AN - OPUS4-38320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Glas an der Bundesanstalt für Materialforschung und -prüfung N2 - Im Vortrag wird ein kurzer Überblick über die BAM und die Aktivitäten zum Werkstoff Glas gegeben. T2 - 4. Glashüttentag der Jungen DGG vom 29.09.2016 bis 30.09.2016 in Berlin CY - Berlin, Germany DA - 29.09.2016 KW - Glas PY - 2016 AN - OPUS4-38331 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Hydrogen permeability of glass measured by VHE-MS powder methods N2 - Glasses are can serve as exceptionally tight hydrogen barriers e.g. used for hydrogen storage in micro glass containers or cover glasses in micro electronic systems. Respective glass development, however, requires precise measurements of minimal hydrogen permeability, PH2. Recent studies showed that PH2 can be measured down to 2 10-21 mol s-1 Pa-1m-1 by means of Vacuum Hot Extraction (VHE) powder methods [1]. In this respect the isothermal gas release from glass powder particles is fitted in terms of classical diffusion models assuming spherical particles of uniform size thus obtaining the hydrogen diffusion coefficient, DH2. PH2 is then given by D H2 × S H2, where hydrogen solubility, SH2, is obtained from VHE studies of glass powders exposed to hydrogen atmosphere for different exposure time and hydrogen pressure. Measurements of minimal values of hydrogen permeability, however, require a careful evaluation and error discussion of this method. Against that background, we modeled hydrogen degassing during heating and subsequent isothermal annealing of glass powder particles of different shape and particle size distribution by means of COMSOL Multiphysics® [2] and verified related effects on DH2 obtained by the VHE powder method. T2 - SGT Centenary Conference, & ESG 2016 CY - Sheffield, UK DA - 4.9.2016 KW - Glass KW - Hydrogen KW - Permeability KW - Storage PY - 2016 AN - OPUS4-38307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Crystallization in multicomponent systems. Glasses for LTCC T2 - Meeting 2008 des TC7 der ICG am Rande der 9th ESG Conf. with the Annual Meeting of the ICG Glass-The challenge for the 21st century CY - Trencín, Slovakia DA - 2008-06-22 PY - 2008 AN - OPUS4-18106 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Eberstein, Markus A1 - Deubener, J. A1 - Thiel, A. A1 - Schiller, Wolfgang Arno T1 - Effects of dispersed Al2O3 particles on sintering of LTCC N2 - The sintering of Low Temperature Co-fired Ceramics prepared from alumoborosilicate glass- and Al2O3 powders of similar small particle size was studied by dilatometry, heating microscopy, microstructure analysis, glass- and effective viscosity measurements. The steric effect of Al3O3 inclusions was studied using a gnon-reactiveh model composite. With increasing Al3O3 volume fraction (Φ ≤ 0.45), sintering decelerates and its final stage shifts to higher temperature. The attainable shrinkage is reduced as Al2O3 particle clusters bearing residual pores become more frequent. The kinetics of sintering could be described formally superposing the weighed contributions of differentially sized and randomly composed glass-crystal particle clusters and assuming a sintering rate controlled by the effective matrix viscosity, which increases with Φ and with progressive wetting of Al2O3 particles during densification. The "reactive" model composite shows significant dissolution of Al2O3 into the glass, which has two opposed effects on sintering: reducing Φ and increasing glass viscosity. For the present case (Φ = 0.25), the latter effect dominates and sintering is retarded by Al2O3 dissolution. Crystallization of wollastonite starts after full densification. Dissolution of Al2O3 was found to promote the subsequent growth of anorthite. KW - LTCC KW - Glass matrix composites KW - Al2O3-inclusions KW - Sintering kinetics PY - 2005 SN - 1022-6680 SN - 1662-8985 VL - 39-40 SP - 375 EP - 380 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-18441 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schiller, Wolfgang Arno A1 - Müller, Ralf A1 - Eberstein, Markus A1 - Reinsch, Stefan A1 - Rabe, Torsten T1 - Sintering of LTCC N2 - Low Temperature Co-fired Ceramic materials (LTCC) have attracted growing interest in recent years since they are promising candidates for highly integrated ceramic packaging. This paper surveys materials concepts of related glass ceramic composites (GCC) and discusses unsolved problems and challenges. The densification of GCC based on "viscous sintering" may be affected by steric effects and partial dissolution of dispersed crystal particles, crystallization and phase boundary reactions. KW - Sintering KW - Glass ceramic composites KW - Viscosity KW - Densification KW - Modelling PY - 2008 SN - 0173-9913 SN - 0196-6219 VL - 85 IS - 13 SP - 12 EP - 17 PB - Göller CY - Baden-Baden AN - OPUS4-19086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ried, Peter A1 - Gaber, Martin A1 - Beyer, Katrin A1 - Müller, Ralf A1 - Kipphardt, Heinrich A1 - Kannengießer, Thomas T1 - Thermo Analytic Investigation of Hydrogen Effusion Behavior - Sensor Evaluation and Calibration N2 - The well established carrier gas analysis (CGA) method was used to test different hydrogen detectors comprising a thermal conductivity detector (TCD) and a metal oxide semiconducting (MOx) sensor. The MOx sensor provides high hydrogen sensitivity and selectivity, whereas the TCD exhibits a much shorter response time and a linear hydrogen concentration dependency. Therefore, the TCD was used for quantitative hydrogen concentration measurements above 50?µmol/mol. The respective calibration was made using N2/H2 gas mixtures. Furthermore, the hydrogen content and degassing behaviour of titanium hydride (TiH2-x) was studied. This material turned out to be a potential candidate for a solid sample calibration. Vacuum hot extraction (VHE) coupled with a mass spectrometer (MS) was then calibrated with TiH2-x as transfer standard. The calibration was applied for the evaluation of the hydrogen content of austenitic steel samples (1.4301) and the comparison of CGA-TCD and VHE-MS. KW - Hydrogen KW - Steel KW - Vacuum hot extraction KW - Carrier gas analysis KW - Titanium hydride KW - Gas calibration PY - 2011 DO - https://doi.org/10.1002/srin.201000237 SN - 1611-3683 SN - 0177-4832 VL - 82 IS - 1 SP - 14 EP - 19 PB - Verl. Stahleisen CY - Düsseldorf AN - OPUS4-23202 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Sinterkinetik von Glasmatrixkompositen für LTCC Anwendungen T2 - DKG - Symp. Simulation und Modellierung von Fertigungsprozesen CY - Erlangen, Germany DA - 2010-11-30 PY - 2010 AN - OPUS4-22521 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Crystal growth kinetics in cordierite and diopside glasses in wide temperature ranges T2 - Intern. Congr. on Glass ICG2010, Annual Meeting TC7, ICG CY - Bahia, Brazil DA - 2010-09-20 PY - 2010 AN - OPUS4-22522 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Sinterability of Glass Powders T2 - Status Seminar, Programm for Developing the Supporting System for Global Mulitidisciplinary Engineering Establishment CY - Nagaoka, Japan DA - 2010-07-29 PY - 2010 AN - OPUS4-22519 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Overall Crystallization Kinetics of Glass Powders T2 - Status Seminar, Programm for Developing the Supporting System for Global Mulitidisciplinary Engineering Establishment CY - Nagaoka, Japan DA - 2010-07-29 PY - 2010 AN - OPUS4-22520 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Agea Blanco, Boris A1 - Blaess, C. A1 - Reinsch, Stefan A1 - Brauer, D. A1 - Müller, Ralf T1 - Sintering and foaming of barium and calcium silicate glass powders N2 - Sintering and foaming of barium and calcium silicate glass powder compacts have been studied for different powder milling. Sintering was measured by means of heating microscopy backed up by XRD, DTA, Vacuum Hot Extraction (VHE) and electron microscopy. Foaming intensity strongly increased with decreasing glass partiefe size. Although powder compacts were uniaxially pressed and sintered in ambient air, foaming was affected by the milling atmosphere and most intensive for milfing in C02. Conformingly, VHE studies revealed that foaming of fully sintered samples was mainly driven by C02, even for powders milled in technical air, Ar and N2. Prolonged storage of air milled barium silicate glass powders in ambient air before pressing and sintering caused further increase of foaming intensity. These findings indicate that carbonaceous species are preferentially trapped to or close beneath the powder surface during milling and later storage. The temperature range of C02 degassing from fully sintered barium and calcium silicate g/ass powder compacts fits the temperature ranges of decomposition of BaC03 and CaC03 mix-milled with the respective barium and calcium silicate glass powders. T2 - IMAPS/ACerS 11th International CICMT conference and exhibition CY - Dresden, Germany DA - 20.04.2015 KW - Sintering KW - Foaming KW - Silicate glass powders KW - Barium and calcium silicate plass powders KW - Degassing PY - 2015 SN - 978-1510804562 SP - 31 EP - 37 AN - OPUS4-35250 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prewitz, Marc A1 - Müller, Ralf A1 - Marotzke, Christian A1 - Holtappels, Kai T1 - Characterization of glass capillary storage modules considering permeability and mechanical stress via finite elements N2 - Glass capillaries are potential candidates for long term hydrogen storage under high pressure. Burst pressure strongly drops with surface damaging, a polymer coating is needed. The aim is to study stress distribution within single coated glass capillaries sealed to metal fittings T2 - 88. Glastechnische Tagung DGG – ACerS GOMD 2014 CY - Aachen, Germany DA - 25.05.2014 KW - Burst test KW - Hydrogen storage KW - Polymer coating PY - 2014 AN - OPUS4-35784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaber, Martin A1 - Müller, Ralf A1 - Höland, W. T1 - Degassing phenomena during sintering and crystallization of glass powders N2 - Degassing may cause trouble in manufacture of sintered glass-ceramics via the Formation of bubbles (deteriorate mechanical strength or surface Quality) T2 - 6th Int. Otto Schott Colloquium CY - Jena, Germany DA - 06.09.1998 KW - Bulk diffusion KW - Sintering KW - Crystallization KW - Melting PY - 1998 AN - OPUS4-35785 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Eberstein, Markus A1 - Müller, Ralf A1 - Schiller, Wolfgang Arno A1 - Schweiger, M. T1 - Lastabhängige Schwindung von Glaspulvern N2 - Glasig-kristalline Sinterwerkstoffe werden für vielfältige Anwendungen eingesetzt. Bei einem hohen Glasanteil ist ein Einfluss geringer Lasten auf das Schwindungsverhalten möglich, so dass es zu Fehlinterpretationen des Schwindungsverhaltens bei gebräuchlichen Horizontaldilatometer kommen kann. T2 - 75. Glasetechnische Tagung CY - Wernigerode, Germany DA - 21.05.2001 KW - Glasig-kristalline Sinterwerkstoffe KW - Schwindungsverhalten KW - Horizontaldilatometer PY - 2001 AN - OPUS4-35786 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marzok, Ulrich A1 - Müller, Ralf A1 - Schadrack, Reinhard A1 - Krauhausen, M. A1 - Reetz, R. T1 - Hochtemperatur-Laserprofilometrie für keramische Proben N2 - Das Hochtemperatur-Laserprofilometer der BAM4 ermöglicht eine 3D-Formerkennung an keramischen Folien oder anderen flachen Objekten während thermischer Behandlungen wie zum Beispiel bei laufenden Entbinderungs- oder Sinterprozessen. Mit dem Lasertriangulationssensor werden das Höhenprofil, die lateralen und axialen Schwindungen und andere charakteristische Maße der Probe wie die Folienbreite und -dicke, Abstände zwischen spezifischen Merkmalen oder Krümmungen bestimmt. Somit können insbesondere auch Deformationen und Verwerfungen der Objekte sowie Schwindungsinhomogenitäten an strukturierten Objekten erkannt und mit dem Herstellungsprozess verknüpft werden. T2 - DKG Jahrestagung 2012 CY - Nuremberg, Germany DA - 05.03.2012 KW - 3D-Formerkennung KW - Lasertriangulationssensor KW - Deformationen KW - Schwindungsinhomogenitäten PY - 2012 AN - OPUS4-35787 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balzer, R. A1 - Behrens, H. A1 - Schuth, S. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Fechtelkord, M. A1 - Deubener, J. T1 - The influence of H2O and SiO2 on the structure of silicoborate glasses N2 - To understand the impact of dissolved water on structure and properties, four boron-rich glasses of molar compositions 15-x Na2O x CaO 15 SiO2 70 B2O3 (with x=0, 7.5, 10) and 10 Na2O 15 SiO2 75 B2O3 were prepared and subsequently hydrated (up to 8 wt% H2O). Density measurements show a non-linear trend upon hydration implying large structural changes in particular at water contents<2 wt%. Near-infrared spectroscopy shows hydroxyl groups are the dominant species in all glasses upon the entire range of water content. Molecular H2O is detectable only at total water contents>2 wt%. 11B MAS NMR spectra show that the abundance of BO4 species is mainly controlled by ratio of (Na2O+CaO)/B2O3 while incorporation of water plays a minor role. Compared to borate glasses, the efficiency of formation of BO4 tetrahedra is favored by crosslinking of the network by SiO4-units. The glass transition temperatures, determined by differential thermal analysis, decreases continuously with water content due to breakage of B-O-B bonds by hydrolysis. However, compared to Silicates and aluminosilicates, the effect of dissolved water is less pronounced which can be explained by weaker B-O-B bonds in comparison to Si-O-Si bonds. KW - High pressure KW - Water speciation KW - Silicoborate glasses KW - Infrared spectroscopy KW - NMR spectroscopy PY - 2019 DO - https://doi.org/10.1016/j.jnoncrysol.2019.05.030 VL - 519 SP - 38 EP - 51 PB - Elsevier B.V. AN - OPUS4-48748 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Waurischk, Tina A1 - Müller, Ralf T1 - Subcritical crack growth in hydrous soda-lime silicate glass N2 - Glass strength and fatigue is limited by surface cracks. As subcritical crack growth (SCCG) is governed by ambient humidity, stress corrosion at the crack tip is widely accepted to be the underlying mechanism. However, as water is known to have decisive effect on glass properties and can rapidly enter the crack tip near glass region, SCCG could be affected by such water related phenomena. We tried to mimic these effects studying water dissolution and speciation, mechanical properties, and SCCG in water-bearing glasses. For this purpose, glasses up to 8 wt% water have been prepared by means of high-pressure melting of glass powder - water mixtures. As part of this effort, SCCG in dry and hydrous commercial micros¬cope slide glass (CW = 6 wt%) was studied in double cantilever beam (DCB) geometry and sub-Tg relaxation was measured by Dynamic Mechanical Analysis (DMA). For SCCG in ambient air (24% r.h.), SCCG was promoted by the presence of 6wt% bulk water with respect to the dry glass. On the other hand, stress intensity values, KI, required to cause slow crack growth (v < 10-6 ms-1) resemble literature findings for float glass of similar composition in liquid water, which might represent the maximum possible promoting effect of ambient water on SCCG. For SCCG in vacuum (10-3 mbar), dissolved bulk water causes even more pronounced effects. Most strikingly, it strongly decreases the slope of the log v(KI)-curve, which is a measure of dissipated energy during fracture. A strong increase of sub-Tg relaxation with increasing water content was confirmed by DMA. As a consequence, slow crack growth occurs at KI values as measured in the dry glass whereas fast crack growth occurs at much larger KI than that of the dry glass. Kinks and shoulders shown by the inert log v(KI)-curve indicate that bulk water does not simply affect bulk mechanical properties. T2 - 9th Otto Schott Colloquium CY - Jena, Germany DA - 09.09.2019 KW - Internal friction KW - Soda-lime silicate glass KW - Crack growth KW - Water content KW - DCB PY - 2019 AN - OPUS4-49534 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kiefer, P. A1 - Balzer, R. A1 - Deubener, J. A1 - Behrens, H. A1 - Waurischk, Tina A1 - Reinsch, Stefan A1 - Müller, Ralf T1 - Density, elastic constants and indentation hardness of hydrous soda-lime silica glasses N2 - The effect of structural water on density, elastic constants and microhardness of water-bearing soda-lime-silica glasses of up to 21.5 mol% total water is studied. It is found that the Poisson ratio and the water content are positively correlated, while density and the elastic moduli decrease with increasing water content. Vickers hardness decreases by approximately 27% from the dry to the most hydrous glass. For water fractions <3 mol%, the dependencies are non-linear reflecting the non-linear change in the concentrations of OH and H2O molecules dissolved, whereas for water fractions >3 mol% linear dependencies are found. To distinguish the effect of structural water and environmental water, indentations were performed in toluene, nitrogen gas and air. Timedependent softening was evident for testing dry glasses in humid atmospheres as well as for tests of hydrous glasses in dry atmospheres. This indicates that the response times of dissolved water species are effectively equal in both scenarios. KW - Elastic constants KW - Soda-lime-silica KW - Glass KW - Water content KW - Microhardness PY - 2019 DO - https://doi.org/10.1016/j.jnoncrysol.2019.119480 SN - 0022-3093 SN - 1873-4812 VL - 521 SP - 119480 PB - Elsevier B.V. AN - OPUS4-48758 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Ralf A1 - Behrens, Harald A1 - Ageo-Blanco, Boris A1 - Reinsch, Stefan A1 - Wirth, Thomas T1 - Foaming Species and Trapping Mechanisms in Barium Silicate Glass Sealants N2 - Barium silicate glass powders 4 h milled in CO2 and Ar and sintered in air are studied with microscopy, total carbon analysis, differential thermal Analysis (DTA), vacuum hot extraction mass spectroscopy (VHE-MS), Fourier-transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary-ion mass spectrometry (TOF-SIMS). Intensive foaming of powder compacts is evident, and VHE studies prove that foaming is predominantly caused by carbonaceous species for both milling gases. DTA Shows that the decomposition of BaCO3 particles mix-milled with glass powders occurs at similar temperatures as foaming of compacts. However, no carbonate at the glass surface could be detected by FTIR spectroscopy, XPS, and TOF-SIMS after heating to the temperature of sintering. Instead, CO2 molecules unable to rotate identified by FTIR spectroscopy after milling, probably trapped by mechanical dissolution into the glass bulk. Such a mechanism or microencapsulation in cracks and particle aggregates can explain the contribution of Ar to foaming after intense milling in Ar atmosphere. The amount of CO2 molecules and Ar, however, cannot fully explain the extent of foaming. Carbonates mechanically dissolved beneath the surface or encapsulated in cracks and micropores of particle aggregates are therefore probably the major foaming source. KW - Milling KW - Foaming KW - Glass powder KW - Sintering PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-531227 DO - https://doi.org/10.1002/adem.202100445 SN - 1438-1656 VL - 24 IS - 6 SP - 2100445-1 EP - 2100445-13 AN - OPUS4-53122 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -