Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (60)
Referierte Publikation
- ja (60) (entfernen)
Schlagworte
- Glass (10)
- Sintering (8)
- Crystallization (7)
- Viscosity (6)
- EBSD (4)
- Vickers indentation (4)
- Water content (4)
- Crystal growth (3)
- Internal friction (3)
- LTCC (3)
- Soda-lime-silica (3)
- Bioactive glass (2)
- Crack healing (2)
- Diopsid (2)
- Foaming (2)
- Glass ceramic composites (2)
- Glass ceramics (2)
- Glass transition (2)
- Glasses (2)
- Incinerator ash (2)
- Infrared spectroscopy (2)
- Mechanical properties (2)
- NMR spectroscopy (2)
- Oxide glasses (2)
- Permeability (2)
- Sewage sludge ash (2)
- Silicates (2)
- Stress intensity factor (2)
- Viskosität (2)
- Water in glass (2)
- Water speciation (2)
- 3D etching (1)
- Additive manufacturing (1)
- Al2O3-inclusions (1)
- Alkali aluminosilicate glasses (1)
- Alkali and alkaline earth silicate and borate glass (1)
- Alkali silicates (1)
- Alumina dissolution (1)
- Aluminium phosphate (1)
- Aluminoborosilicate glass (1)
- Aluminosilicate glasses (1)
- Aluminum phosphate (1)
- Analytical scanning electron microscopy (1)
- Ash (1)
- Automated analysis (1)
- Batch reactions (1)
- Bioactive Glass (1)
- Borate (1)
- Borate glasses (1)
- Boratgläser (1)
- Borosilicate glass (1)
- Brittle fracture (1)
- Bubble formation (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)
- Corrosion (1)
- Crack growth (1)
- Crack growth in air (1)
- Cristobalite form (1)
- Crystal morphology (1)
- Crystal orientation (1)
- DCB (1)
- DCB geometry (1)
- DTA (1)
- Debindering (1)
- Densification (1)
- Diffusivity (1)
- Effective Viscosity (1)
- Efficiency (1)
- Elastic constants (1)
- Epoxy resin (1)
- Fluorescence properties (1)
- Fly ash (1)
- Fracture surface energy (1)
- Fragility (1)
- Fresnoite (1)
- Gas calibration (1)
- Glass Ceramic (1)
- Glass Matrix Composites (1)
- Glass capillaries (1)
- Glass ceramic (1)
- Glass crystallization stress (1)
- Glass forming melts (1)
- Glass manufacturing (1)
- Glass matrix composites (1)
- Glass powder (1)
- Glass-ceramic (1)
- Glass-ceramics definition (1)
- Hardness (1)
- High pressure (1)
- Hydrogen (1)
- Hydrogen diffusivity (1)
- Hydrogen gas (1)
- Hydrogen storage (1)
- Hydrous glass (1)
- Inclusions (1)
- Indentation (1)
- Indentation fracture toughness (1)
- Ion beam erosion Sectioning (1)
- Ionic porosity (1)
- Kinetic Modelling (1)
- Kinetik (1)
- Kristallisation (1)
- Kristallwachstumsgeschwindigkeit (1)
- Lithiumionen-Batterie (1)
- Long-term calculation (1)
- Luminescence (1)
- Mass spectroscopy (1)
- Master curve (1)
- Microhardness (1)
- Microindentation (1)
- Microscopy (1)
- Milling (1)
- Mixing (1)
- Modeling (1)
- Modelling (1)
- Nanoparticles (1)
- Nucleation (1)
- Nydrogen melting (1)
- Optical microscopy (1)
- Optical properties (1)
- Optical solids (1)
- Optical spectroscopy (1)
- Orientation (1)
- Phasenentwicklung (1)
- Phosphate (1)
- Photovoltaic modules (1)
- Porosity (1)
- Powder preparation (1)
- Powders (1)
- Precursor chemistry (1)
- Raman spectroscopy (1)
- Relaxation (1)
- Rheology (1)
- Rietveld analysis (1)
- Rigid Inclusion (1)
- Roughness (1)
- SEM (1)
- SOFC (1)
- Sample preparation (1)
- Sand blasting (1)
- Scaffolds (1)
- Scanning electron microscopy (1)
- Shaping (1)
- Shear thinning (1)
- Silicate glass (1)
- Silicatgläser (1)
- Silicoborate glasses (1)
- Silikatgläser (1)
- Silver metallization paste (1)
- Sintering glass composit bio material (1)
- Sintering kinetics (1)
- Slow crack growth (1)
- Soda lime silicate glass (1)
- Soda-lime silicate glass (1)
- Soda-lime-silica glass (1)
- Sodium ion batteries (1)
- Sol-gel (1)
- Solid-state reaction (1)
- Solubility (1)
- Stable crack growth (1)
- Stacking disorder (1)
- Steel (1)
- Strength (1)
- Stress intensity (1)
- Stress-corrosion (1)
- Structural relaxation (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)
- Titanium hydride (1)
- Toughness (1)
- Transmittance (1)
- Tridymite form (1)
- Ultrasonic relaxation (1)
- Unterschiedliche Atmosphären (1)
- Vacuum hot extraction (1)
- Wassergehalt (1)
- Wasserhaltige Gläser (1)
- Water (1)
- Water-bearing glasses (1)
- X-ray lithography (1)
Organisationseinheit der BAM
Oriented surface crystallization on polished diopside glass surfaces has been studied with scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy and laser scanning microscopy.
An orientation preference of [001] parallel to the glass surface was detected for separately growing diopside crystals even as small as 700 nm in size. This finding shows that crystal orientation occurs in the outermost surface layer without crystal-crystal interaction and indicates that the crystal orientation is a result of oriented nucleation. Depending on surface preparation, monomodal crystal orientation distributions with [100] perpendicular to the surface or bimodal distributions with [100] and [010] perpendicular to the glass Surface were detected. It was also shown that the degree of crystal orientation increases with decreasing Surface roughness. The observed orientation of diopside crystals could be explained in terms of the interfacial energies of different crystal faces.
Lithium disilicate, leucite and apatite glass-ceramics have become state-of-the-art framework materials in the fabrication of all-ceramic dental restorative materials. The goal of this study was to examine the crack propagation behaviour of these three known glass-ceramic materials after they have been subjected to Vickers indentation and to characterize their crack opening profiles (δmeas vs. (a-r)). For this purpose, various methods of optical examination were employed. Optical microscopy investigations were performed to examine the crack phenomena at a macroscopic level, while high-resolution techniques, such as scanning electron microscopy (SEM) and atomic force microscopy (AFM), were employed to investigate the crack phenomena at a microscopic level. The crack patterns of the three glass-ceramics vary from fairly straightforward to more complex, depending on the amount of residual glass matrix present in the material. The high-strength lithium disilicate crystals feature a high degree of crosslinking, thereby preventing crack propagation. In this material, the crack propagates only through the residual glass phase, which constitutes 30%40% by volume. Having a high glass content of more than 65% by volume, the leucite and apatite glass-ceramics show far more complex crack patterns. Cracks in the leucite glass-ceramic propagate through both the glass and crystal phase. The apatite glass-ceramic shows a similar crack behaviour as an inorganicorganic composite material containing nanoscale fillers, which are pulled out in the surroundings of the crack tip. The observed crack behaviour and the calculated View the MathML source values of the three types of glass-ceramics were compared to the Kkic values determined according to the SEVNB method.
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.
Green compacts of ceramics, glass ceramic composites and sinter glass ceramics contain
different amounts of organic materials added as pressing aids or binders. Before sintering, these
organics have to burn out completely. In oxidising atmospheres, the debindering process is mostly
exothermic and therefore difficult to control. This uncontrolled heat production due to locally enhanced
debindering and respective gas release may cause damages in the green compact microstructure.
Therefore, debindering is usually operated with very low heating rates (< 3 K/min) which requires
long processing times of many hours. In this paper, we will show that it is possible to reduce
the processing time for debindering dramatically by using the decomposition rate of the organic
binder, detected by the weight loss of the sample, as a control factor of the furnace.
Sample preparation for analytical scanning electron microscopy using initial notch sectioning
(2021)
A novel method for broad ion beam based sample sectioning using the concept of initial notches is presented. An adapted sample geometry is utilized in order to create terraces with a well-define d step in erosion depth from the surface. The method consists of milling a notch into the surface, followed by glancing-angle ion beam erosion, which leads to preferential erosion at the notch due to increased local surface elevation. The process of terrace formation can be utilized in sample preparation for analytical scanning electron microscopy in order to get efficient access to the depth-dependent microstructure of a material. It is demonstrated that the method can be applied to both conducting and non-conducting specimens. Furthermore, experimental parameters influencing the preparation success are determined. Finally, as a proof-of-concept, an electron backscatter diffraction study on a surface crystallized diopside glass ceramic is performed, where the method is used to analyze orientation dependent crystal growth phenomena occurring during growth of surface crystals into the bulk.
Sand erosion of solar glass: Specific energy uptake, total transmittance, and module efficiency
(2018)
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.
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.
Thermally stimulated interactions between silver and glass, that is, silver dissolution as Ag+ and precipitation as Ag0 were studied in two glass series of molar target composition xAg2O–(19 − x)Na2O–28ZnO–53B2O3 with x = 0, 0.1, 0.5, 5 and (19Na2O–28ZnO–53B2O3)+yAg2O with y = 0.01, 0.05. These act as model for low-melting borate glasses being part of metallization pastes. The occurrence of metallic silver precipitates in melt-quenched glass ingots demonstrated that silver dissolved only in traces (< 0.01 mol%) in the glasses. The dissolved silver was detected by means of Raman spectroscopy and energy-dispersive X-ray spectroscopy. Increasing x in the batch could not lead to a significant increase of the silver ion fraction in the glass as possible in binary silver borate glasses. In situ observation of heated AgNO3 mixed with the base glass frit in a hot stage microscope showed that Ag0 precipitation occurs already at the solid state. At higher temperatures, small droplets of liquid silver were found to move freely within the melt, whereas coalescence caused a stepwise increase of their size.
These results contribute to the understanding of formation of silver precipitates in metallization pastes described in the literature.
The sintering of bioactive glasses allows for the preparation of complex structures, such as three‐dimensional porous scaffolds. Such 3D constructs are particularly interesting for clinical applications of bioactive glasses in bone regeneration, as the scaffolds can act as a guide for in‐growing bone cells, allowing for good Integration with existing and newly formed tissue while the scaffold slowly degrades. Owing to the pronounced tendency of many bioactive glasses to crystallize upon heat treatment, 3D scaffolds have not been much exploited commercially. Here, we investigate the influence of crystallization on the sintering behavior of several bioactive glasses. In a series of mixed‐alkali glasses an increased CaO/alkali metal oxide Ratio improved sintering compared to Bioglass 45S5, where dense sintering was inhibited.
Addition of small amounts of calcium fluoride helped to keep melting and sintering temperatures low. Unlike glass 13‐93, these new glasses crystallized during sintering but this did not prevent densification. Variation in bioactive glass particle size allowed for fine‐tuning the microporosity resulting from the sintering process.
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.