5 Werkstofftechnik
Filtern
Erscheinungsjahr
- 2021 (89) (entfernen)
Dokumenttyp
- Vortrag (56)
- Zeitschriftenartikel (10)
- Beitrag zu einem Tagungsband (10)
- Posterpräsentation (8)
- Buchkapitel (1)
- Corrigendum (1)
- Dissertation (1)
- Sonstiges (1)
- Forschungsdatensatz (1)
Sprache
- Englisch (89) (entfernen)
Referierte Publikation
- nein (89) (entfernen)
Schlagworte
- Corrosion (15)
- Additive Manufacturing (6)
- Additive manufacturing (5)
- Steel (5)
- CCS (4)
- Microstructure (4)
- Ontology (4)
- CO2 quality (3)
- Carbon capture storage (3)
- Crack growth (3)
- Crack tip opening displacement (3)
- Creep behavior (3)
- Fatigue (3)
- Geothermal (3)
- High-temperature corrosion (3)
- Impurities (3)
- Martensitic steel (3)
- Pipeline network (3)
- Recommendations (3)
- Thermoelectrics (3)
- Thermomechanical fatigue (3)
- Whole-chain CCS scenario (3)
- 316L (2)
- Agglomerates (2)
- Alkali ions (2)
- CCU (2)
- CO2 (2)
- Ceramics (2)
- Chemically complex alloy (2)
- Chromium oxide (2)
- Coatings (2)
- Corrosion fatigue (2)
- Creep (2)
- Dispersion process (2)
- EBSD (2)
- Environmental stress cracking (2)
- Fe-Al alloys (2)
- Glass fiber reinforced polymers (2)
- High alloyed steel (2)
- High entropy alloys (2)
- High-density polyethylene (2)
- High-entropy alloys (2)
- Hydrogen (2)
- Intermetallics (2)
- Inverted classroom (2)
- Iron aluminides (2)
- Manganese oxide (2)
- Mechanical properties (2)
- Microstrucrue Design (2)
- Microstructural analysis (2)
- Nano-powder (2)
- Oxidation (2)
- Oxidation behavior (2)
- PMD (2)
- Polyaniline (2)
- Protective coating (2)
- Residual Stress (2)
- SiO2 (2)
- Sibayak (2)
- Sintering (2)
- Sol-gel coating (2)
- Spectroscopy (2)
- Standardization (2)
- Tensile Test (2)
- Thermoelectric (2)
- Transmission electron microscopy (2)
- Wall thickness (2)
- AGIL (1)
- AISI 316L (1)
- AM (1)
- Additive Fertigung (1)
- Ageing (1)
- Al2O3 (1)
- Alkali zinc borate glass (1)
- Analytical services (1)
- Anisotropy (1)
- Binder Jetting (1)
- Bio-ceramic engineering (1)
- Blended learning (1)
- Borate glasses (1)
- Burst test (1)
- CALPHAD (1)
- CO2-storage (1)
- Cabon capture and storage (1)
- Carbon capture and storage (1)
- Catalogue of services (1)
- Centrifugal casting (1)
- Ceramic (1)
- Ceramic multilayer (1)
- Ceramics 3D printing (1)
- Characterization (1)
- Coating (1)
- Complex borides (1)
- Composite (1)
- Composite pressure vessels (1)
- Compositionally complex alloys (1)
- Contamination (1)
- Cooling simulations (1)
- Cow stress (1)
- Cr2O3 (1)
- Crystal Defects (1)
- Crystal plasticity (1)
- Crystallization (1)
- Damage (1)
- Damage Tolerance (1)
- Damage mechanisms (1)
- Deep learning (1)
- Defects (1)
- Defects phase diagram (1)
- Defects thermodynamics (1)
- Density-based Thermodynamics (1)
- Density-based model (1)
- Die casting (1)
- Dielectric breakdown (1)
- Dielectric strength (1)
- Diffraction (1)
- Digitization (1)
- Dislocation substructure (1)
- Diversity (1)
- EC4SafeNano (1)
- EDXRD (1)
- Electric field strength (1)
- Electron diffraction (1)
- European Centre (1)
- Fatigue performance (1)
- Fem (1)
- Ferritic Alloys (1)
- Fiber (1)
- First year students (1)
- Flipped classroom (1)
- Focussed ion beam growth (1)
- Fractography (1)
- Fracture behavior (1)
- Fracture surface (1)
- Full Notch Creep Test (1)
- Fungi (1)
- Gas storage (1)
- Gitterkonstanten (1)
- Glass fiber reinforced polymer (1)
- Glass fibre reinforced plastics (1)
- Glass forming (1)
- Glass structure (1)
- HEA (1)
- HV-Insulation (1)
- Hard machining (1)
- Hardness (1)
- Heat treatment (1)
- High Cycle Fatigue (1)
- High Temperature Corrosion (1)
- High alloyed steels (1)
- High entropy superalloys (1)
- High temperature (1)
- High-Temperature Corrosion (1)
- Hochentropie-Legierung (1)
- Hot pressing (1)
- In-situ (1)
- Interfacial Spinodal (1)
- Investment casting (1)
- Iron oxide nanoparticles (1)
- Kikuchi diffraction (1)
- Knowledge Graphs (1)
- Laser powder bed fusion (1)
- Layerwise Slurry Deposition (1)
- Lecture films (1)
- Lecture videos (1)
- Legierung mit komplexer Zusammensetzung (1)
- Lithography-based technologies (1)
- Low Cycle Fatigue (1)
- MEA (1)
- Metallic silver precipitates (1)
- Microbiologically influenced corrosion (1)
- Micromanipulation (1)
- Microstructural orientation (1)
- Missing acknowledgment (1)
- Monte-Carlo-Analysis (1)
- Multilayer (1)
- Multilayertechnik (1)
- Nano metal fluorides (1)
- Nano-landscape (1)
- Nano-safety (1)
- Nanomaterials (1)
- Nanoparticles (1)
- Net zero (1)
- Neutron Diffraction (1)
- Nickel-base alloy (1)
- Nickel-base superalloys (1)
- Nimonic 75 (1)
- Non-desired foaming (1)
- Normung (1)
- Online teaching (1)
- Ontology development (1)
- Optic (1)
- Orientation-dependent microstructure (1)
- Oxides (1)
- Particle size (1)
- Pattern matching (1)
- Phase separation (1)
- Phasenidentifikation (1)
- Pipeline (1)
- Platform Material Digital (1)
- Platform Material Digital (PMD) (1)
- Platform MaterialDigital (1)
- Pole figures (1)
- Polymer Matrix Composites (1)
- Polymer-Ceramic-Composite (1)
- Polymer-ceramic mixtures (1)
- Porosity (1)
- Portfolio (1)
- Powder bed density (1)
- Powder-based processes (1)
- Preparation (1)
- Pressure assisted sintering (1)
- Reference data (1)
- Reference material (1)
- Reference material BCR-425 (1)
- Refractory chemically complex alloys (1)
- Residual stress (1)
- SEM (1)
- SHM (1)
- SIMS (1)
- Sample preparation (1)
- Scarf joint repair (1)
- Scarf repairs (1)
- Screen printing (1)
- Semantic Web (1)
- Silver diffusion (1)
- Silver-glass-metallization-paste (1)
- Single-Crystal (1)
- Sintering atmosphere (1)
- Small angle x-ray scattering (1)
- Solid solution strengthening (1)
- Solidification (1)
- Solubility (1)
- Spinodal Decomposition (1)
- Spring constant (1)
- Standard (1)
- Strain rate dependence (1)
- Sulfidation (1)
- Superalloys (1)
- Supercritical CO2 (1)
- Superlegierung (1)
- Synchrotron radiation (1)
- Technical Ceramics (1)
- Temperature (1)
- Tensile test (1)
- Termites (1)
- Thermal stress (1)
- Thermo mechanical fatigue (1)
- Thermo-mechanical-loading (1)
- Thermo-mechanics (1)
- Ti-6Al-4V (1)
- Transmission electron microscope (TEM) (1)
- Transmission electron microscopy (TEM) (1)
- Two-photon adsorption (1)
- Viscosity (1)
- Wind turbine blade shell structures (1)
- Wood protection (1)
- XRD (1)
- Young´s Modulus (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (89) (entfernen)
Eingeladener Vortrag
- nein (56)
Laser powder bed fusion (LPBF) is an additive manufacturing process for materials which inherently tends to yield various degrees of metastable hierarchical microstructures, defects and high residual stresses in the as-built condition depending on the process parameters. The understanding of the evolution of these typical features during heat treatment and subsequent thermal and mechanical ageing is crucial for the wider acceptance for safety critical structures. A multi-disciplinary research project at BAM studying the development of the microstructure, defects, residual stresses typical of LPBF 316L and their evolution during thermal and mechanical ageing has led to insights into the stability of these inherent features. This presentation aims to give a broad overview of the project with a few specific cases of investigation. Firstly, the formation of residual stresses, the nature of the initial microstructure, the tensile properties and a modelling approach to understand the anisotropy will be presented. This will be followed by examples of studies of their evolution during heat treatment, long term thermal exposure, and room temperature and high temperature mechanical testing compared to a baseline of conventional wrought variant of the same alloy.
Low melting zinc borate glasses awake interest to replace lead borate glasses in the silver metallization pastes for solar cells or microelectronics. In the current study, characteristic properties of alkali zinc borate glasses (X2O-ZnO-B2O3, X = Li, Na, K, Rb) were compared to an earth alkali zinc borate glass (CaO-ZnO-B2O3). Additionally, zinc oxide is partially substituted by lead oxide or cooper oxide in the borate glasses (Li2O-PbO-B2O3, Na2O ZnO CuO-B2O3). The alkali zinc borate glasses indicate less differences in Raman spectra, and thus in structural properties, in comparison to the Ca and Pb ions influence. LPbB (Tg = 401 °C) has a lower viscosity than LZB (Tg = 468 °C) and CaZB has the highest glass transition temperature (Tg = 580 °C). The Angell plot for the alkali zinc borate glasses shows a high fragility m = 80. Besides Tg, the density measured by means of the Archimedean principle, molar volume, and coefficient of thermal expansion (CTE) of the glasses were investigated. Trends could be found according to alkali ions or intermediate oxides. The density increases with decreasing alkali ion size from KZB (2.632 g/cm3) to LZB (2.829 g/cm3) and increases from LZB to LPbB (3.764 g/cm3). CTE ranges between 7.09 10-6 K-1 for CaZB and 11.5 10 6 K 1 for KZB and RZB. The differential thermal analysis (DTA) and X ray diffraction (XRD) indicate crystallization of various crystalline phases during heating with 5 K/min in most cases.
Ceramic multilayer technology is an attractive approach for the cost-effective fabrication of thermoelectric generators. Therefore, efforts are being made to co-sinter two promising thermoelectric oxides, namely calcium cobaltite and calcium manganate. In this study, calcium cobaltite, calcium manganate and release tapes were pressure assisted sintered. A major challenge here is the cracking of calcium manganate during cooling. A relationship between the properties of the release tape used in pressure-assisted sintering and the cracking behavior was observed experimentally.
To understand the origin of failure, formed reaction layers in the multilayer were analyzed by EDX and grazing incident XRD. Based on this analysis, bulk samples were prepared, and thermal expansion and Young's modulus and were determined thereon, if they were not known from the literature. The biaxial strength of the thermoelectric oxides was determined by the ball on three ball method.
The thermal stresses during cooling of different multilayer designs were estimated by finite element simulations. The stresses caused by the reaction layers turned out to be negligible. The FEM study indicated further, and a validation experiment proved, that the thickness of the release tape has the main effect on thermal stresses during cooling in single material. For best performance, the design of a thermoelectric multilayer generator needs to consider thermoelectric performance and thermal stresses during cooling.
CALM is software for determining the Bravais lattice type and the resulting lattice parameters from a single Kikuchi pattern. It requires the definition of 4 bands and a single bandwidth from which all other band positions as well as bandwidths are derived. For band detection, it uses the Funk transform, which allows detection of twice as many bands as usual. CALM works for any symmetry and requires low-noise patterns of at least 320x240 pixels. The resulting errors are <2% even for such small patterns, assuming good quality. The relative errors are <0.5%. However, this requires a projection centre position best derived from a sample of a cubic phase in CALM. However, this must have been recorded under identical conditions. Hundreds of Kikuchi patterns of phases with different symmetries were examined.
The Gibbs free energy of a grain boundary is a complex thermodynamic function of temperature, pressure, and composition. These complexities add to the intrinsic crystallographic and chemical constraints imposed by the adjacent bulk phase. Recently we have proposed a density-based model for assessing grain boundary thermodynamics that enables a CALPHAD-informed description of the grain boundary. As such, the Gibbs free energy of the grain boundary is directly linked with available CALPHAD thermodynamic data. In this talk, new aspects of interfacial segregation and phase transformation are revealed by benchmarking the current model for various experimental cases, including several steels, high-entropy alloys and aluminum alloys. The effects of elastic interactions on the grain boundary segregation and the application of the model to a nanocrystalline Pt-Au alloy, with numerous grain boundaries of various characters, will be discussed.
The following work deals with the quantitative fracture surface evaluation in damage analysis. So far, fracture surfaces have almost exclusively been evaluated qualitatively, i.e. the presence of fracture features is documented and their surface proportions are estimated, if necessary. Many years of experience are required, as well as an intensive comparison with defined comparative images from the literature. The aim of this work is the development of classifiers which can recognize fracture mechanisms or fracture features in scanning electron microscope images (SEM). The basis is 46 SEM images, which have been evaluated by fractography experts with regard to fracture features. The existing data set of images is expanded using augmentation methods in order to increase the variability of the data and counteract overfitting. Only convolutional neural networks (CNN) are used to create the classifiers. Various network configurations are tested, with the SegNet achieving the best results.
Reliable characterization of materials at the nanoscale regarding their physio-chemical properties is a challenging task, which is important when utilizing and designing nanoscale materials. Nanoscale materials pose a potential toxicological hazard to the environment and the human body. For this reason, the European Commission amended the REACH Regulation in 2018 to govern the classification of nanomaterials, relying on number-based distribution of the particle size.
Suitable methods exist for the granulometric characterization of monodisperse and ideally shaped nanoparticles. However, the evaluation of commercially available nanoscale powders is problematic. These powders tend to agglomerate, show a wide particle size distribution and are of irregular particle shape.
Zinc oxide, aluminum oxide and cerium oxide with particle sizes less than 100 nm were selected for the studies and different preparation methods were used comparatively.
First, the nanoparticles were dispersed in different dispersants and prepared on TEM-supported copper grids. Furthermore, individual powders were deposited on carbon-based self-adhesive pads. In addition, the samples were embedded by hot mounting and then ground and polished.
The prepared samples were investigated by scanning electron microscopy (including the transmission mode STEM-in-SEM) and Dynamic Light scattering. The software package ImageJ was used to segment the SEM images and obtain the particle sizes and shapes and finally the number-based particles size distribution with size expressed as various descriptors.
Additively Manufactured (AM) parts are still far from being used in safety-relevant applications, mainly due to a lack of understanding of the feedstock-process-propertiesperformance relationship. This work aims at providing a characterization of the fatigue behavior of the additively manufactured AISI 316L austenitic stainless steel and a direct comparison with the fatigue performance of the wrought steel. A set of specimens has been produced by laser powder bed fusion (L-PBF) and a second set of specimens has been machined out of hot-rolled plates. The L-PBF material shows a higher fatigue limit and better finite life performance compared to the wrought material, accompanied by an extensive amount of cyclic softening.
The phenomenon of expelling nanomaterial from microparticles of different materials, such as Au, WO3 or B2O3 under the influence of a convergent electron beam (CB) of a transmission electron microscope (TEM) was reviewed by Ignacio Gonzalez-Martinez [1]. Converging the e-beam in a TEM means that a high amount of energy enters the microparticle at a very local place and interact with the matter. Obviously, during the convergent beam protocol, no imaging with the electron beam is possible, but at the end, nanoparticles with different appearances lie down next to the microparticle while its size is reduced.
Hence, there is a blind spot in the observation, which we want to fill, as we want to help clarify the nature of the expelling phenomenon. One hypothesis that explains the phenomenon is the so-called damage (of the microparticle) induced by an electric field (DIEF). Within this theory, the material is ionized and expelled in form of ionic waves. Our aim is therefore to fabricate specimens with artificial microlandscapes, as schematically exemplified in figure 1a), using the focused ion beam (FIB) and micromanipulators, as experimental setups to follow the paths of the expelled material.
As a first step towards the fabrication of such specimen, we make experimental feasibility studies for each fabrication method, FIB structuring with Ga+ ion beam and micromanipulated microparticle deposition. Bridges (gray regions in Fig. 1) are created by milling a commercially available electron transparent membrane (silicon oxide or carbon) of a Cu-TEM grid. Platinum or carbon walls (blue features in Fig. 1) are built to stand on those bridges. Microparticles (yellow sphere in Fig. 1) of gold or other material are deposited in the center of the bridges.
Figure 2a) shows four square holes (black area) and between them the residual silicon oxide membrane bridges (dark grey). On top of the bridges, walls (light grey) are deposited. The width of the bridges is different, the walls overlap the holes as well as the distance between the walls is very small, so these and other parameters need to be optimized. Figure 2b) shows a square hole (black) with bridges (white) on the right side on top of a carbon membrane (grey). There are still some obstacles which needs to be eliminated. For instance, the deposition process of the walls is not reliable as visible at the wall on top where a hole arises instead of a wall.
These studies are still in progress and the results are further discussed in terms of the applicability for the DIEF experiment in the TEM.