Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (79)
- Vortrag (52)
- Beitrag zu einem Tagungsband (18)
- Beitrag zu einem Sammelband (13)
- Posterpräsentation (12)
- Buchkapitel (2)
- Forschungsbericht (1)
Sprache
- Englisch (113)
- Deutsch (61)
- Mongolisch (3)
Schlagworte
- Glass (26)
- Sintering (20)
- Crystallization (10)
- LTCC (9)
- Foaming (7)
- Glas (7)
- Sintern (7)
- Viscosity (7)
- Water content (5)
- Crystal growth (4)
- EBSD (4)
- Inclusions (4)
- Internal friction (4)
- Kristallisation (4)
- Permeability (4)
- Solubility (4)
- Vickers indentation (4)
- Degassing (3)
- Glass matrix composites (3)
- Glass powder (3)
- Hydrogen (3)
- Modeling (3)
- Ontologie (3)
- Robotic melting (3)
- SOFC (3)
- Simulation (3)
- Sintering kinetics (3)
- Soda-lime-silica (3)
- Water (3)
- Workflow (3)
- Aluminosilicate glasses (2)
- Bildanalyse (2)
- Bioactive glass (2)
- Crack growth (2)
- Crack healing (2)
- DCB (2)
- Data Space (2)
- Diffusion (2)
- Diffusion coefficient (2)
- Diffusivity (2)
- Digitaler Zwilling (2)
- Diopsid (2)
- Fatigue (2)
- Fracture surface energy (2)
- Fragility (2)
- Glasmatrixkomposite (2)
- Glaspulver (2)
- Glass ceramic composites (2)
- Glass ceramics (2)
- Glass transition (2)
- Glasses (2)
- Hydrogen storage (2)
- Incinerator ash (2)
- Infrared spectroscopy (2)
- Ionic porosity (2)
- Lösung (2)
- ML (2)
- Mechanical properties (2)
- Modelling (2)
- NMR spectroscopy (2)
- Ontology (2)
- Oxide glasses (2)
- Oxidglas (2)
- Powder (2)
- Powders (2)
- Relaxation (2)
- Reprecipitation (2)
- Sewage sludge ash (2)
- Silicate glass (2)
- Silicates (2)
- Silikatgläser (2)
- Silver (2)
- Soda-lime silicate glass (2)
- Stress intensity factor (2)
- Viskosität (2)
- Wasser (2)
- Wassergehalt (2)
- Water in glass (2)
- Water speciation (2)
- 3D High-temperature shape screening (1)
- 3D etching (1)
- 3D-Formerkennung (1)
- Acid-leaching (1)
- Additive manufacturing (1)
- Al2O3-inclusions (1)
- Alkali aluminosilicate glasses (1)
- Alkali and alkaline earth silicate and borate glass (1)
- Alkali silicates (1)
- Alkali zinc borate glasses (1)
- Alpha-cordierite (1)
- Alumina dissolution (1)
- Aluminium phosphate (1)
- Aluminoborosilicate glass (1)
- Aluminum phosphate (1)
- Analytical scanning electron microscopy (1)
- Ash (1)
- Automated analysis (1)
- Back-filling specimen mount technique (1)
- Barium and calcium silicate plass powders (1)
- Batch reactions (1)
- Bioactive Glass (1)
- Blähen (1)
- Bond energy (1)
- Borate (1)
- Borate glasses (1)
- Boratgläser (1)
- Borosilicate glass (1)
- Brittle fracture (1)
- Bubble formation (1)
- Bulk diffusion (1)
- Burst test (1)
- Calculated intrinsic fracture toughness (1)
- Carrier gas analysis (1)
- Chemical durability (1)
- Chemical properties (1)
- Chemical stabilization of high-temperature forms (1)
- Coating (1)
- Cordierite (1)
- Corrosion (1)
- Crack growth in air (1)
- Cristobalite form (1)
- Crystal lattice (1)
- Crystal morphology (1)
- Crystal orientation (1)
- DCB geometry (1)
- DTA (1)
- Debindering (1)
- Deformationen (1)
- Densification (1)
- Diopside (1)
- Dissolved water (1)
- Dynamic mechanical analysis (1)
- Dynamisch Mechanische Analyse (1)
- Effective Viscosity (1)
- Efficiency (1)
- Elastic constants (1)
- Embedded cavities (1)
- Epoxy resin (1)
- Finite Differenzen (1)
- Fluorescence properties (1)
- Fly ash (1)
- Formerkennung (1)
- Formmessung (1)
- Fresnoite (1)
- Gas bubble formation (1)
- Gas calibration (1)
- Gasabgabe (1)
- Gasgehalt (1)
- Gehalt volatiler Spezies (1)
- Glas Matrix Composites (1)
- Glasig-kristalline Sinterwerkstoffe (1)
- Glasmatrix-Komposit (1)
- Glasmatrixkomposit (1)
- Glass Ceramic (1)
- Glass Matrix Composites (1)
- Glass capillaries (1)
- Glass ceramic (1)
- Glass crystallization stress (1)
- Glass forming melts (1)
- Glass liner (1)
- Glass manufacturing (1)
- Glass-ceramic (1)
- Glass-ceramics definition (1)
- Goldcluster (1)
- Hardness (1)
- Heißextraktion (1)
- Heißgasextraktion (1)
- High pressure (1)
- High temperature laser profilometry (1)
- Hochtemperatur (1)
- Hochtemperaturformerkennung (1)
- Horizontaldilatometer (1)
- Hydrogen diffusivity (1)
- Hydrogen gas (1)
- Hydrogen permeation (1)
- Hydrogen storage tank (1)
- Hydrous glass (1)
- Indentation (1)
- Indentation fracture toughness (1)
- Indialite (1)
- Ion beam erosion Sectioning (1)
- Keramikherstellung (1)
- Kinetic Modelling (1)
- Kinetik (1)
- Komposite (1)
- Kontur (1)
- Kristallwachstumsgeschwindigkeit (1)
- LTCC multilayer (1)
- Laser (1)
- Laser profilometry (1)
- Lasermesstechnik (1)
- Lasertriangulationssensor (1)
- Lead borate glasses (1)
- Lithiumionen-Batterie (1)
- Long-term calculation (1)
- Low pressure lamination (1)
- Luminescence (1)
- Mass spectroscopy (1)
- Master curve (1)
- Material Digital (1)
- Melting (1)
- Metallnanocluster (1)
- Micro fluidics (1)
- Microhardness (1)
- Microindentation (1)
- Microscopy (1)
- Milling (1)
- Mixing (1)
- Multilayer-Technik (1)
- Nanoparticles (1)
- Nanophotonik (1)
- Nanopowder (1)
- Non-desired foaming (1)
- Nucleation (1)
- Nucleation tendency (1)
- Nydrogen melting (1)
- Oberflächenkeimbildung (1)
- Optical microscopy (1)
- Optical properties (1)
- Optical solids (1)
- Optical spectroscopy (1)
- Optische Eigenschaften (1)
- Orientation (1)
- Phasenentwicklung (1)
- Phosphate (1)
- Photovoltaic modules (1)
- Polymer coating (1)
- Porosity (1)
- Powder preparation (1)
- Precursor chemistry (1)
- Prozessbegleitende Prüfung (1)
- Pulvermethode (1)
- Raman spectroscopy (1)
- Relaxationsphänomene (1)
- Rheology (1)
- Rietveld analysis (1)
- Rigid Inclusion (1)
- Robotische Glasschmelzanlage (1)
- Roughness (1)
- SEM (1)
- Sample preparation (1)
- Sand blasting (1)
- Scaffolds (1)
- Scanning electron microscopy (1)
- Schwindungsinhomogenitäten (1)
- Schwindungsverhalten (1)
- Shaping (1)
- Shear thinning (1)
- SiO2 (1)
- Silicate glass powders (1)
- Silicate glasses and crystals (1)
- Silicatglas (1)
- Silicatgläser (1)
- Silicoborate glasses (1)
- Silver metallization paste (1)
- Sinter retardation (1)
- Sinterglaskeramik (1)
- Sintering Kinetics (1)
- Sintering glass composit bio material (1)
- Sintermodelle (1)
- Sinterung (1)
- Slow crack growth (1)
- Soda lime silicate glass (1)
- Soda-lime-silica glass (1)
- Sodium ion batteries (1)
- Sol-gel (1)
- Solid-state reaction (1)
- Stable crack growth (1)
- Stacking disorder (1)
- Standard material (1)
- Steel (1)
- Storage (1)
- Strength (1)
- Stress intensity (1)
- Stress-corrosion (1)
- Structural relaxation (1)
- Struktur (1)
- Subcritical crack growth (1)
- Surface crystallization (1)
- Surface energy (1)
- Surface nucleation (1)
- Surface plasmon resonance (1)
- Surfaces and interfaces (1)
- Synchrotron radiation (1)
- Thermal analysis (1)
- Thermische Analyse (1)
- Thermo gravimetry (1)
- Thermoanalytical Methods (1)
- Titanium hydride (1)
- Toughness (1)
- Transmittance (1)
- Tridymite form (1)
- Ultrasonic relaxation (1)
- Unterschiedliche Atmosphären (1)
- Vacuum hot extraction (1)
- Viscous sintering (1)
- Viskoses Sintern (1)
- Wasserhaltige Gläser (1)
- Water-bearing glasses (1)
- X-ray lithography (1)
- hydrogen storage (1)
- robotische Glasschmelzanlage (1)
Organisationseinheit der BAM
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.
Wasser in Silicatglas
(2018)
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.
Glass-ceramics are noted for their unusual combination of properties and manifold commercialized products for consumer and specialized markets. Evolution of novel glass and ceramic processing routes, a plethora of new compositions, and unique exotic nano- and microstructures over the past 60 years led us to review the Definition of glass-ceramics. Well-established and emerging processing methods, such as co-firing, additive manufacturing, and laser patterning are analyzed concerning the core requirements of processing glass-ceramics and the Performance of the final products. In this communication, we propose a revised, updated definition of glass-ceramics, which reads “Glass-ceramics are inorganic, non-metallic materials prepared by controlled crystallization of glasses via different processing methods. They contain at least one type of functional crystalline phase and a residual glass. The volume fraction crystallized may vary from ppm to almost 100%”.
Glasses with compositions of 21Gd2O3-63MoO3-(16-x)B2O3-xTeO2 (mol%) (x= 0, 2, 4, 8) were prepared using a conventional melt quenching technique, and the crystallization behavior of ferroelastic β′-Gd2 MoO4)3 Crystals was examined to clarify the mechanism of self-powdering phenomenon and to design bulk crystallized glasses. It was found that the self-powdering phenomenon appeared significantly during the crystallization at temperatures near the crystallization peak temperature, but the phenomenon is suppressed in the crystallization at temperatures much higher than the glass transition temperature. It was also found that the substitution of TeO2 for B2O3 in the base glasses suppresses the self-powdering phenomenon and consequently bulk crystallized glasses were obtained in the glass with x=8 mol%. The densities at room temperature of the base glasses are d =4.755–4.906 g/cm3, being much higher than the value of d=4.555 g/cm3 for β′-Gd2(MoO4)3 crystal. It is proposed that the stresses in the inside of crystals induced by large density differences (i.e., large molar volume differences) between the glassy phase and crystals might be relaxed effectively in the glasses containing TeO2 with weak TeeO bonds and fragile character.
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.
In this review article, the impact of dissolved water on the viscous properties of soda lime silicate melts is addressed against the background of the upcoming switch from natural gas to hydrogen combustion. This change will lead to an increase in the total water content of the glasses by up to 0.4 mol%. In order to better define possible influences of water speciation, water-rich glasses were synthesised under increasing pressure up to the kbar range. It is shown that a distinction must be made between the influence of dissolved OH-groups and H2Omolecules in order to accurately reflect the dependence of isokom temperatures on water content. In addition, an increase of one order of magnitude in the tolerance to higher deformation rates was observed for the range of expected increased water contents during isothermal deformation processes, which is based on the timetemperature superposition principle, i.e. congruent flow curves were determined under isokomal conditions.
The permeation of hydrogen gas was studied in meta-aluminous (tectosilicate) glass powders of Li2O×Al2O3×SiO2 (LAS), Na2O×Al2O3×SiO2 (NAS) and MgO×Al2O3×SiO2 (MAS) systems by pressure loading and vacuum extraction in the temperatures range 210–310 °C. With this method, both the solubility S and the diffusivity D were determined, while the permeability was given by the product SD. For all glasses, S was found to decrease with temperature, while D increased. Since the activation energy of diffusion of H2 molecules exceeded that of dissolution, permeation increased slightly with temperature. When extrapolated to standard conditions (25 °C), the permeability of tectosilicate glasses was found to be only 10-22–10-24 mol H2 (m s Pa)-1, which is 8–10 magnitudes lower than most polymers. Thin glass liners of these compositions are expected to be the most effective barrier for tanks of pressurised hydrogen.
AbstractViscous healing of cracks induced by the Vickers indentation in a soda lime magnesium silicate, a soda borosilicate, and a soda aluminosilicate glass (NAS) was studied by laser scanning microscopy. Plots of the crack length, width, and depth normalized to the initial crack length versus time over viscosity merge into single master curves of each of these quantities for each glass. Despite glass properties do not differ strikingly from each other, however, these master curves strongly differ among the glasses. This finding was attributed to a different interplay of various crack healing phenomena. Lateral cracks were found to be responsible for the bulging of the sample surface around the Vickers imprint, which in turn promotes radial crack widening as the main cause of healing delay. The most rapid healing of lateral cracks was observed in NAS in which bulging and crack widening were least pronounced.
Silicate glass fracture surface energy calculated from crystal structure and bond-energy data
(2023)
We present a novel method to predict the fracture surface energy, γ, of isochemically crystallizing silicate glasses using readily available crystallographic structure data of their crystalline counterpart and tabled diatomic chemical bond energies, D0. The method assumes that γ equals the fracture surface energy of the most likely cleavage plane of the crystal. Calculated values were in excellent agreement with those calculated from glass density, network connectivity and D0 data in earlier work. This finding demonstrates a remarkable equivalence between crystal cleavage planes and glass fracture surfaces.
Controlled oriented crystallization of glass surfaces is desired for high precision applications, since the uppermost crystal layer significantly influences the properties of the material. In contrast to previous studies, the data presented here deal with separated crystals growing at defect-free surfaces in four atmospheres with different degrees of humidity (ambient/dry air, argon and vacuum). A glass with the composition 2 BaO–TiO2–2.75 SiO2 was heat-treated at 825 °C until fresnoite (Ba2TiSi2O8) grew to a significant size. The crystal growth rate is found to increase with increasing humidity. The morphology of the crystals changes from highly distorted dendrites in the driest atmosphere (vacuum) to circular/spear-head-shaped crystals in the wettest atmosphere (ambient air), which we attribute to a decrease in viscosity of the glass surface due to water uptake. The least distorted crystals appear in the form of depressions of up to 6 µm. This has an influence on the observed crystal orientation, as measured by electron backscatter diffraction (EBSD). The pulled-in crystals change the orientation during growth relative to the flat glass surface due to an enrichment in SiO2 at the crystal fronts. This confirms that the orientation of crystals is not fixed following nucleation.
The process of viscous flow sintering is a phenomenon that is closely linked to the surface properties of the glass particles. In this work, we studied the extreme case of acid-leaching of soda-lime-silicate glass beads of two different particle size distributions and its effects on non-isothermal viscous sintering of powder compacts. Depth profiling of the chemical composition after leaching revealed a near-surface layer depleted in alkali and alkaline earth ions, associated with concurrent hydration as mass loss was detected by thermogravimetry. Heating microscopy showed that acid treatment of glasses shifted the sinter curves to higher temperatures with increasing leaching time. Modelling of the shrinkage with the cluster model predicted a higher viscosity of the altered surface layer, while analysis of the time scales of mass transport of mobile species (Na+, Ca2+ and H2O) during isochronous sintering revealed that diffusion of Na+ can compensate for concentration gradients before sintering begins. Also, exchanged water species can diffuse out of the altered layer, but the depletion of Ca2+ in the altered surface layer persists during the sinter interval, resulting in a glass with higher viscosity, which causes sintering to slow down.
This study investigates the sintering and crystallization behavior and kinetic of the bioactive glass (BG) 13–93 with nominal composition (in mol%): 54.6 SiO2 - 1.7 P2O3 - 22.1 CaO - 6.0 Na2O - 7.9 K2O - 7.7 MgO. Sintering and crystallization were investigated non-isothermally for various particle size fractions smaller than 315 μm as well as for bulk samples. Densification was not hindered by the presence of crystalline phases across all particle size fractions. Afterwards, wollastonite was found as the dominant crystal phase at higher temperature which resorb primary surface precipitation-like quartz crystallites. The growth direction shifts into volume when the sample surface is nearly covered. The crystal growth rate of wollastonite was calculated from the crystalline surface layer thickness measured during heating. The findings of this study are relevant for the high temperature processing of BG 13–93.
Glasses stand out by their wide and continuously tunable chemical composition and large variety of unique shaping techniques making them a key component of modern high technologies. Glass development, however, is still often too cost-, time- and energy-intensive. The use of robotic melting systems embedded in an ontology-based digital environment is intended to overcome these problems in future. As part of the German research initiative MaterialDigital, the joint project GlasDigital takes first steps in this direction. The project consortium involves the Fraunhofer ISC in Würzburg, the Friedrich Schiller University Jena (OSIM), the Clausthal University of Technology (INW), and the Federal Institute for Materials Research and Testing (BAM, Division Glasses) and aims to combine all main basic components required for accelerated data driven glass development. For this purpose, a robotic high throughput glass melting system is equipped with novel inline sensors for process monitoring, machine learning (ML)-based, adaptive algorithms for process monitoring and optimization, novel tools for high throughput glass analysis and ML-based algorithms for glass design, including software tools for data mining as well as property and process modelling. The talk gives an overview how all these tools are interconnected and illustrates their usability with some examples.
Gläser zeichnen sich durch eine breite und kontinuierlich abstimmbare chemische Zusammensetzung sowie einzigartige Formgebungstechniken aus, was sie oft zur Schlüsselkomponente moderner Hochtechnologien macht. Die Glasentwicklung ist jedoch oft noch zu kosten-, zeit- und energieintensiv. Der Einsatz von robotergestützten Schmelzsystemen, eingebettet in eine Ontologie-basierte digitale Umgebung, soll diese Probleme in Zukunft überwinden. Im Rahmen der BMBF Forschungsinitiative MaterialDigital unternimmt das Verbundprojekt GlasDigital „Datengetriebener Workflow für die beschleunigte Entwicklung von Glas“ erste Schritte in diese Richtung. Das Projektkonsortium, an dem das Fraunhofer ISC in Würzburg, die Friedrich-Schiller-Universität Jena (OSIM), die Technische Universität Clausthal (INW) und die Bundesanstalt für Materialforschung und -prüfung (BAM, Fachgruppe Glas) beteiligt sind, will alle wesentlichen Basiskomponenten für eine beschleunigte datengetriebene Glasentwicklung zusammenführen. Zu diesem Zweck wird ein robotergestütztes Hochdurchsatz-Glasschmelzsystem mit neuartigen Inline-Sensoren zur Prozessüberwachung, auf maschinellem Lernen (ML) basierenden adaptiven Algorithmen zur Prozessüberwachung und -optimierung, neuartigen Werkzeugen für die Hochdurchsatz-Glasanalyse sowie ML-basierten Algorithmen zum Glasdesign, Data Mining sowie Eigenschafts- und Prozessmodellierung ausgestattet. Der Vortrag gibt einen Überblick darüber, wie all diese Komponenten miteinander verzahnt sind, und veranschaulicht ihre Nutzbarkeit anhand einiger Beispiele.
lasses stand out by their wide and continuously tunable chemical composition and large variety of unique shaping techniques making them a key component of modern high technologies. Glass development, however, is still often too cost-, time- and energy-intensive. The use of robotic melting systems embedded in an ontology-based digital environment is intended to overcome these problems in future. As part of the German research initiative MaterialDigital, the joint project GlasDigital takes first steps in this direction. The project consortium involves the Fraunhofer ISC in Würzburg, the Friedrich Schiller University Jena (OSIM), the Clausthal University of Technology (INW), and the Federal Institute for Materials Research and Testing (BAM, Division Glasses) and aims to combine all main basic components required for accelerated data driven glass development. For this purpose, a robotic high throughput glass melting system is equipped with novel inline sensors for process monitoring, machine learning (ML)-based, adaptive algorithms for process monitoring and optimization, novel tools for high throughput glass analysis and ML-based algorithms for glass design, including software tools for data mining as well as property and process modelling. The talk gives an overview how all these tools are interconnected and illustrates their usability with some examples.