5 Werkstofftechnik
Filtern
Dokumenttyp
- Vortrag (431) (entfernen)
Sprache
- Englisch (332)
- Deutsch (96)
- Mehrsprachig (3)
Referierte Publikation
- nein (431) (entfernen)
Schlagworte
- Additive Manufacturing (38)
- Additive manufacturing (24)
- Microstructure (21)
- Corrosion (20)
- Glass (18)
- Ontology (17)
- Fatigue (13)
- Ceramics (12)
- LCF (11)
- 316L (10)
- Additive Fertigung (10)
- Creep (10)
- Ontologie (10)
- Transmission electron microscopy (10)
- Crack growth (9)
- Fraktographie (9)
- Sintering (9)
- Ceramic (8)
- Thermoelectrics (8)
- Diffraction (7)
- Fractography (7)
- Machine Learning (7)
- Particle size (7)
- Powder (7)
- Ti-6Al-4V (7)
- CCUS (6)
- DCB (6)
- Digitalisierung (6)
- EBSD (6)
- Glas (6)
- High entropy alloys (6)
- Low Cycle Fatigue (6)
- Mikrostruktur (6)
- Scanning electron microscopy (6)
- Zugversuch (6)
- 3D printing (5)
- AGIL (5)
- Aluminium (5)
- Anisotropy (5)
- Crystal plasticity (5)
- Crystallization (5)
- Glass fiber reinforced polymers (5)
- In situ (5)
- Microgravity (5)
- Oxidation (5)
- Slurry (5)
- VSSA (5)
- Water speciation (5)
- AISI 316L (4)
- Alloy 2618A (4)
- CALPHAD (4)
- CCS (4)
- CO2 (4)
- Coarsening (4)
- Creep behavior (4)
- Degradation (4)
- Droplet corrosion (4)
- EN AW-2618A (4)
- FAIR (4)
- FAIR data management (4)
- Fatigue crack growth (4)
- Fe-Al alloys (4)
- Foaming (4)
- High-temperature corrosion (4)
- In-space manufacturing (4)
- Intermetallics (4)
- Iron aluminides (4)
- Kriechen (4)
- Laser powder bed fusion (4)
- Layerwise slurry deposition (4)
- Martensitic steel (4)
- Mechanical properties (4)
- Nano (4)
- Nano powder (4)
- Neutron diffraction (4)
- Nickel-base superalloys (4)
- Non-destructive testing (4)
- Normung (4)
- Plattform MaterialDigital (4)
- Polymer matrix composites (4)
- Residual Stress (4)
- Semantic Web Technologies (4)
- Sulfidation (4)
- Supercritical/dense phase CO2 (4)
- TMF (4)
- Thermomechanical fatigue (4)
- Vickers (4)
- Wissensrepräsentation (4)
- Alkali ions (3)
- Alumina (3)
- Aluminium Alloy (3)
- Aluminium alloy (3)
- Betriebsfestigkeit (3)
- CCU (3)
- Carbon steels (3)
- Ceramic spring (3)
- Computed Tomography (3)
- Dielectric strength (3)
- Fracture surface (3)
- Full Notch Creep Test (3)
- Gassensorik (3)
- Geothermal (3)
- H2Safety@BAM (3)
- Heat treatment (3)
- High temperature corrosion (3)
- Keramik (3)
- Knowledge graph and ontologies (3)
- Lebensdauer (3)
- Mechanical behavior (3)
- Mechanical testing (3)
- Mikroplastik (3)
- Ni-Resist (3)
- PMD (3)
- Residual stress (3)
- S-phase (3)
- SEM (3)
- Scarf repairs (3)
- Semantic Interoperability (3)
- Silicate Glasses (3)
- Soda-lime silicate glass (3)
- Superaustenite steel (3)
- Tensile Test (3)
- Texture (3)
- Transmission electron microscopy (TEM) (3)
- Wasser (3)
- Water content (3)
- Welding (3)
- Wind turbine blades (3)
- X-ray diffraction (3)
- Zerstörungsfreie Prüfung (3)
- μ-gravity (3)
- Advanced ceramics (2)
- Alkali zinc borate glasses (2)
- Alterung (2)
- Analytische Zentrifuge (2)
- Bildanalyse (2)
- CLS (2)
- CO2 quality (2)
- CT (2)
- Calciumcobaltit (2)
- Calciummanganat (2)
- Carbon capture (2)
- Carbon capture storage (2)
- Carbon dioxide (2)
- Carbon steel (2)
- Characterization (2)
- Chemically complex alloy (2)
- Composite (2)
- Composites (2)
- Concrete (2)
- Copper (2)
- Crack tip opening displacement (2)
- Creep data (2)
- Dark-field transmission electron microscopy (2)
- Data Fusion (2)
- Data Interoperability (2)
- Data mapping (2)
- Datenbank (2)
- Dielectric breakdown (2)
- Diesel (2)
- Diffraction Elastic Constants (2)
- Diffusion (2)
- Digital image correlation (2)
- Digitaler Zwilling (2)
- Digitalization (2)
- Digitization (2)
- Digtial Representation (2)
- Diopside (2)
- Dislocation (2)
- EDXRD (2)
- Electron microscopy (2)
- Electron-beam-induced modification (2)
- Electronic Lab Notebook (2)
- Environmental Stress Cracking (2)
- Environmental stress cracking (2)
- Faser-Kunststoff-Verbunde (2)
- Faserkunststoffverbunde (2)
- Faseroptische Sensorik (2)
- Ferritic-martensitic steels (2)
- Fracture Toughness (2)
- Full-Notch Creep Test (FNCT) (2)
- Geführte Ultraschallwellen (2)
- Gitterkonstanten (2)
- Glass-ceramics (2)
- Hard machining (2)
- High Cycle Fatigue (2)
- High Entropy Alloy (2)
- High Temperature Corrosion (2)
- High temperature (2)
- High temperature mechanical properties (2)
- High-entropy alloy (2)
- High-entropy alloys (2)
- Hochentropie-Legierung (2)
- Hochtemperatur (2)
- Impurities (2)
- In-situ (2)
- Interoperability (2)
- Joined nickel-based alloys (2)
- L-PBF (2)
- Laser (2)
- Laser Powder Bed Fusion (2)
- Laser Powder Bed fusion (2)
- Laser beam melting (2)
- Layerwise (2)
- Leckdetektion (2)
- Lunar regolith simulant (2)
- ML (2)
- Material Digital (2)
- Material digital (2)
- Metrologie zur Wasserstoffspeicherung (2)
- Microplastics (2)
- Microstrucrue Design (2)
- Microstructural analysis (2)
- Microstructure Design (2)
- Mixed gas atmosphere (2)
- Modeling (2)
- Multilayer (2)
- Multilayer technology (2)
- Multilayertechnik (2)
- NDT (2)
- Nano particle (2)
- Nano screening (2)
- Nano-powder (2)
- Nanomaterial (2)
- Nanoparticles (2)
- Nanopulver (2)
- Notches (2)
- OECD TG 124 (2)
- Ontologien (2)
- Ontology development (2)
- Orientation (2)
- Oriented surface crystallization (2)
- Oxidation behavior (2)
- Oxide Glasses (2)
- Oxidglas (2)
- PBF-LB/M/316L (2)
- PE-HD (2)
- PMD Core Ontology (2)
- PMDco (2)
- Partikelgrößenverteilung (2)
- Phase-field simulation (2)
- Phasenidentifikation (2)
- Pipeline (2)
- Plattform Material Digital (2)
- Polyethylen (2)
- Polyethylen hoher Dichte (2)
- Polymer Matrix Composites (2)
- Process monitoring (2)
- Push-out Test (2)
- REM (2)
- Reaction sintering (2)
- Residual Stresses (2)
- Ressidual stress (2)
- Rotor blade (2)
- Sandwich (2)
- Scale-bridging (2)
- Schadensanalyse (2)
- Schädigung (2)
- Selective Laser Melting (2)
- Semantic Representation (2)
- Semantic Web (2)
- Semantisches Web (2)
- SensRef (2)
- Silicon Carbide (2)
- Silver diffusion (2)
- Silver-glass-metallization-paste (2)
- Simulation (2)
- Sinter additive (2)
- Sintering additives (2)
- Sintern (2)
- Spannungsriss (2)
- Spectroscopy (2)
- Spray drying (2)
- Spring constant (2)
- Standard (2)
- Standardisierung (2)
- Standardization (2)
- Structural Health Monitoring (SHM) (2)
- Superlegierung (2)
- Surface energy (2)
- TED-GC-MS (2)
- TEM (2)
- Tensile Test Ontology (2)
- Tensile data (2)
- Tensile test (2)
- Thermo-Mechanical Fatigue (2)
- Thermoelectric (2)
- Ti64 (2)
- TiAl5V4 (2)
- Titan (2)
- Topographie (2)
- Topography (2)
- UV-irradiation (2)
- Ultrasound (2)
- Virtual experiments (2)
- Viscoplasticity (2)
- Viscosity (2)
- Wall thickness (2)
- Wind turbine blade shells (2)
- Windenergie (2)
- XANES (2)
- XRD (2)
- Zero-g (2)
- Zugeigenschaften (2)
- robotische Glasschmelzanlage (2)
- µ-gravity (2)
- 3D (1)
- 3D Druck (1)
- 3D REM (1)
- 3D Reconstruction (1)
- 3D glass structure model (1)
- 3D materialography (1)
- 3D-printing (1)
- 9-12% Cr ferritic-martensitic steels (1)
- 9–12%Cr steel (1)
- AFM based test methods (1)
- AM (1)
- Accelerated integration scheme (1)
- Acids (1)
- Active thermography (1)
- Additiv gefertigter Stahl (1)
- Adiabatic shear bands (1)
- Advanced manufacturing (1)
- Aerospace (1)
- Age hardening (1)
- Ageing (1)
- Agglomerates (1)
- Aggressive gases (1)
- Aging (1)
- Air-coupled ultrasonic testing (1)
- Airborne ultrasonic testing (1)
- Al-Li alloys (1)
- Alkali zinc borate glass (1)
- Aluminum (1)
- Aluminum alloys (1)
- Analyse (1)
- Analysis (1)
- Analytik (1)
- Annealing (1)
- Atmospheric plasma spraying (1)
- Aussonderugnsrate (1)
- Austenitic cast iron (1)
- Austenitic steel 316L (1)
- Automatable digital approach (1)
- Automation (1)
- BET (1)
- Biaxial strength (1)
- Binder jetting (1)
- Bioactive (1)
- Bioactive Glass (1)
- Bioceramics (1)
- Biodiesel (1)
- Blähen (1)
- Bond energy (1)
- Breakdown strength (1)
- Brinell hardness (1)
- Bruchflächen (1)
- Bruchflächenanalyse (1)
- Bruchflächenauswertung (1)
- Bundesoberbehörden (1)
- CFK (1)
- CO2-corrosion (1)
- Calcination (1)
- Calcium cobaltite (1)
- Calcium manganate (1)
- Calcium sulfates (1)
- Calibration (1)
- Cantor alloy (1)
- Capture (1)
- Carbon (1)
- Carbon steels (1)
- Carbon Capture (1)
- Carbon Capture, Utilization and Storage (CCUS) (1)
- Carbon Fiber Reinforced Plastics (1)
- Carbon Fibers (1)
- Casting (1)
- Centrifugal casting (1)
- Ceramic multilayer (1)
- Ceramic springs (1)
- Certification Standard 22 (1)
- Certified Referencematerial (1)
- Cetrifugal Liquid Sedimentation CLS (1)
- Chemically complex alloys (1)
- Chemo-mechanical coupling (1)
- Chromatography (1)
- Chromia (1)
- Chromium oxide (1)
- Co-firing (1)
- Co-segregation (1)
- Coatings (1)
- Complex borides (1)
- Complex loading (1)
- Component assessment (1)
- Composite testing (1)
- Compositionally complex alloys (1)
- Computed tomography (1)
- Condensation (1)
- Contamination (1)
- Continnum damage model (1)
- Cooling simulations (1)
- Cow stress (1)
- Cr2O3 (1)
- Crack (1)
- Crack Propagation (1)
- Crack evolution (1)
- Crack propagation (1)
- Creep anisotropy (1)
- Creep behaviour (1)
- Creep-Fatigue (1)
- Creep-fatigue (1)
- Crevice corrosion (1)
- Cross linking (1)
- Crystal Defects (1)
- Crystal Orientation (1)
- Crystal Plasticity Modelling (1)
- Cubical Iron Oxide (1)
- Cure process (1)
- Cycle jump (1)
- Cyclic R-Curve (1)
- Cyclic oxidation (1)
- Cyclic softening (1)
- DIN (1)
- DLS (1)
- Damage (1)
- Damage Behavior (1)
- Damage Tolerance (1)
- Damage behavior (1)
- Damage mechanisms (1)
- Dark-field transmission electron microscopy (DFTEM) (1)
- Data Exchange (1)
- Data Management (1)
- Data Structures (1)
- Data linking (1)
- Data management (1)
- Data pipeline concept (1)
- Data space (1)
- Data storage (1)
- Data structure (1)
- Datenökosystem (1)
- Deep learning (1)
- Defects (1)
- Defects phase diagram (1)
- Defects thermodynamics (1)
- Deformation behavior (1)
- Dehnungsfehler (1)
- Density (1)
- Density-based Thermodynamics (1)
- Density-based model (1)
- Density-based phase-field modelling (1)
- Dental (1)
- Destabilization (1)
- Die casting (1)
- Dielectric breakdown strength (1)
- Dielectric characterization (1)
- Diffraction Enhanced Imaging (1)
- Diffraction contrast (1)
- Diffusion coefficient (1)
- Digital representation (1)
- Digital workflow (1)
- Dislocation substructure (1)
- Dislocations (1)
- Disordered assemblies (1)
- Dispersion process (1)
- Dissimilar metal weld (1)
- Dissolved water (1)
- Distribution function (1)
- Driving physical mechanism (1)
- Dual-energy (1)
- Durchschlagfestigkeit (1)
- Dynamic mechanical analysis (1)
- Dynamic mechanical analysis (DMA) (1)
- Dynamisch Mechanische Analyse (1)
- EAC-1A (1)
- EASA (1)
- EDX (1)
- EN AW 2618A (1)
- Early oxidation (1)
- Eigenspannung (1)
- Elastic constants (1)
- Electric field distribution (1)
- Electric field strength (1)
- Electrical insulation (1)
- Electron Backscatter Diffraction (1)
- Electron Microscopy (1)
- Electron backscatter diffraction (1)
- Electron backscattered diffraction (EBSD) (1)
- Elektronisches Laborbuch (ELN) (1)
- Energy harvesting (1)
- Entwicklung (1)
- Environmental Stress Cracking (ESC) (1)
- Ermüdung (1)
- Ermüdungsriss (1)
- Erneuerbare Energien (1)
- Etching (1)
- Extensometer (1)
- FAIR Data Management (1)
- FAIR data (1)
- FCH JU (1)
- FIB (1)
- Fabrication method (1)
- Fahrrad (1)
- Failure test (1)
- Faser (1)
- Faseroptik (1)
- Faserverstärkte Kunstoffe (1)
- Fatigue Crack Growth (1)
- Fatigue Life Evaluation (1)
- Fatigue damage (1)
- Fatigue fracture (1)
- Fatigue of sandwich shell structures (1)
- Fatigue of sandwich structures (1)
- Fatigue performance (1)
- FeCr- alloys (1)
- Federkonstante (1)
- Feldspar (1)
- Fem (1)
- Ferritic Alloys (1)
- Ferroelectret (1)
- Ferroelektret (1)
- Fertigungstechnologie (1)
- Festigkeit (1)
- Fiber (1)
- Fiber reinforced polymer (1)
- Fiber reinforced polymers (1)
- Fine Powder (1)
- Finite element analysis (1)
- Finite elmenet simulation (1)
- Flowability (1)
- Fluorescence spectroscopy (1)
- Focused Ion Beam (1)
- Foliengießen (1)
- Force-distance diagram (1)
- Formerkennung (1)
- Fracture Mechanics (1)
- Fracture Surface Analysis (1)
- Fracture behavior (1)
- Fracture surface analysis (1)
- Fracture toughness (1)
- Freeze Drying (1)
- GC-MS (1)
- GD-OES (1)
- Gas storage (1)
- Gasabgabe (1)
- Gasgehalt (1)
- Gasturbinen (1)
- Gefüge (1)
- General Aviation (1)
- Geopolymers (1)
- Gitterfehlpassung (1)
- Glasmatrixkomposit (1)
- Glass Fibres (1)
- Glass composition (1)
- Glass fibre reinforced plastics (1)
- Glass melting (1)
- Glass powder (1)
- Glass screening device (1)
- Gold nanoparticle synthesis (1)
- Gold nanoparticles (1)
- Gradient-enhanced damage (1)
- Grain boundaries (1)
- Grain boundary engineering (1)
- Granules (1)
- Granulometrie (1)
- Graphic design (1)
- Grünfolieneigenschaften (1)
- HDPE Soprption (1)
- HEA (1)
- HIP (1)
- Hardness (1)
- Hartbearbeitung (1)
- Heat Treatment (1)
- Heat Treatments (1)
- Heißgasextraktion (1)
- Heißgaskorrosion (1)
- High Entropy Alloys (1)
- High Temperature Testing (1)
- High entropy alloy (1)
- High entropy superalloys (1)
- High-Temperature Corrosion (1)
- High-density polyethylene (1)
- Hochentropielegierungen (1)
- Hochspannungsprüfung (1)
- Hochtemperaturbrennstoffzelle (1)
- Hochtemperaturermüdung (1)
- Horizon 2020 (1)
- Hot Press (1)
- Hot isostatic pressing (1)
- Hot pressing (1)
- Hydrogen (1)
- Hydrogen permeation (1)
- Hydrogen sensor (1)
- Hydrogen sensors (1)
- Hyper-arid (1)
- IN 718 (1)
- IN738LC (1)
- IR (1)
- ISRU (1)
- Implant failures (1)
- Implants (1)
- In situ tensile test (1)
- In-Situ Testing (1)
- Inconel 686 coating (1)
- Inconel 718 (1)
- Infrastructure (1)
- Initial attachment (1)
- Injection (1)
- Interface (1)
- Interface Strength (1)
- Interfacial Spinodal (1)
- Internal friction (1)
- Inverse ostwald ripening (1)
- Investment casting (1)
- Iron oxide nanoparticles (1)
- Kalzinierung (1)
- Kavitation (1)
- Kennwertermittlung (1)
- Keramikfeder (1)
- Keramische Folien (1)
- Klebung (1)
- Kleinprobenprüfung (1)
- Knowledge Graphs (1)
- Knowledge Representation (1)
- Knowledge graph (1)
- Kontrastierung (1)
- Korrosion (1)
- Kriechversuche (1)
- Kristallisation (1)
- Kunststoffe (1)
- Kupfer (1)
- Kurzzeitfestigkeit (1)
- L-PBF 316L (1)
- LSD-print (1)
- LTCC (1)
- Laminography (1)
- Laser Poeder Bed Fusion (1)
- Laser Scanning Microscopy (LSM) (1)
- Laser cladding (1)
- Laser curing (1)
- Laser induced slipcasting (1)
- Laserbearbeitung (1)
- Laserscanningmikroskopie (LSM) (1)
- Lattice misfit (1)
- Layer depostion (1)
- Layer system (1)
- Layerwise Slurry Deposition (1)
- Legierung mit komplexer Zusammensetzung (1)
- Li-ion battery (1)
- Life cycle (1)
- Lightweight materials (1)
- Lightweighting (1)
- Lithium Ion Batteries (1)
- Localized plasmons (1)
- Long-term storage (1)
- Low cycle fatigue (1)
- Low-Cycle-Fatigue (1)
- Low-cycle-fatigue behaviour (1)
- Luftultraschall (1)
- Lunar habitat (1)
- Lösungsmittel (1)
- MEA (1)
- Manganese oxide (1)
- Manufacturing (1)
- Martensitic steel (1)
- Mat-o-lab (1)
- Material Life Cycle (1)
- Material defects (1)
- MaterialDigital (1)
- Materialcharakterisierung (1)
- Materialentwicklung (1)
- Materialmodell (1)
- Materials Data Space (1)
- Materials Modelling (1)
- Materials Science (1)
- Materials and Processes Data Reusability (1)
- Materials science (1)
- Materials testing (1)
- Materialwissenschaft (1)
- Matrix (1)
- Mechanical and thermal testing (1)
- Mechanische Eigenschaften (1)
- Mechanisches Verhalten (1)
- Mechanistic Modelling (1)
- Medium Entropy Alloys (1)
- Medium entopy alloy (1)
- Medium-entropy alloy (1)
- Melt pool boundary (1)
- Metadata schema (1)
- Metallic components (1)
- Metallic silver precipitates (1)
- Metallography (1)
- Metrologie (1)
- Micro-shrinkages (1)
- Microbiologically influenced corrosion (1)
- Microhardness (1)
- Micromechanical model (1)
- Microstructural characterization (1)
- Microstructural evolution (1)
- Microstructural orientation (1)
- Microstructure Characterization (1)
- Microstructure Evolution (1)
- Microstructure characterisation (1)
- Microstructure design (1)
- Microstructure evolution (1)
- Microstructure modification (1)
- Microstructure-property-correlation (1)
- Mid-Level Ontology for MSE (1)
- Mikro-Computertomographie (1)
- Mikrogravitation (1)
- Mikrostrukturentwicklung (1)
- Mindedestberstdruck (1)
- Mixed Ca-K-Na phosphates (1)
- Mn3O4 (1)
- Modell (1)
- Monte-Carlo Simulation (1)
- Mortar (1)
- Mortel (1)
- Multi-principal element alloys (1)
- Multiaxial stress state (1)
- NTE (1)
- Na and K rhenanites (1)
- Nano material (1)
- Nano-assemblies (1)
- Nanoparticle synthesis (1)
- Nanopartikel (1)
- Nanoplattform (1)
- Negative charged microparticle (1)
- Neutron Diffraction (1)
- New standards (1)
- Nickel-base superalloy (1)
- Non-desired foaming (1)
- Nondestructive testing (1)
- Nucleation (1)
- Nucleation mode (1)
- OECD TG (1)
- Oberflächenaktive wässrige Medien (1)
- Online quality control (1)
- Ontologies (1)
- Ooxidation (1)
- Optic (1)
- Overaging (1)
- Oxide glass (1)
- P92 (1)
- P92 steels (1)
- PA6.6 (1)
- PPA (1)
- Parametric modeling (1)
- Particle size determination (1)
- Partikelgröße (1)
- Patent (1)
- Paving (1)
- Phase Diagrams (1)
- Phase Separation (1)
- Phase analysis (1)
- Phase diagram (1)
- Phase field simulation (1)
- Phase separation (1)
- Phase transformation (1)
- Phase transformations (1)
- Phase-Field Simulation (1)
- Phase-Field Simulations (1)
- Phase-field Simulation (1)
- Photon counting detector (1)
- Physically based material model (1)
- Physics-informed Neural Network (1)
- Pipeline network (1)
- Planetary surface (1)
- Platform Material Digital (1)
- Platform Material Digital (PMD) (1)
- Platform MaterialDigital (1)
- Platform MaterialDigital (PMD) (1)
- Plattform Material Digital (PMD) (1)
- Pole figures (1)
- Polyaniline (1)
- Polyethylene, PE-HD (1)
- Polymer (1)
- Polymer Matrix Composite (1)
- Polymerwissenschaften (1)
- Porcelain (1)
- Pores (1)
- Powder deposition (1)
- Power plant (1)
- Precipitates (1)
- Precipitation (1)
- Precipitation Analysis (1)
- Precipitation hardening (1)
- Preparation (1)
- Pressure assisted sintering (1)
- Pressure-assisted sintering (1)
- Probengrößeneffekt (1)
- Protective coating (1)
- Präparation (1)
- Pull-out (1)
- Pycnometry (1)
- Quantitative Precipitation Analysis (1)
- Quantitative image analysis (1)
- Rafting (1)
- Recommendations (1)
- Recycling (1)
- Reference data (1)
- Reference material (1)
- Referenzdaten (1)
- Refractory chemically complex alloy (1)
- Refractory chemically complex alloys (1)
- Regelwerke (1)
- Relaxation (1)
- Relaxation metallic glasses (1)
- Relaxationsphänomene (1)
- Repair of sandwich shell structures (1)
- Reproducibility (1)
- Research Data Management (1)
- Residual stress analysis (1)
- Residual stresses (1)
- Resistance (1)
- Restberstfestigkeit (1)
- Review (1)
- Rissentwicklung (1)
- Rissheilung (1)
- Risswachstum (1)
- Roboter (1)
- Robotic melting (1)
- Robotische Schmelzanlage (1)
- Rotorblattschalen (1)
- Roughness (1)
- Röntgen-Refraktion (1)
- Röntgenbeugung (1)
- Röntgenrefraktion (1)
- S355 steel sheet (1)
- SHM (1)
- SIMS (1)
- SLM (1)
- Safety assessment (1)
- Sailplane Development Panel (1)
- Salzschmelzen (1)
- Sample preparation (1)
- Sandwich structures (1)
- Scanning Electron Microscopy (SEM) (1)
- Scanning electron microscope (1)
- Scanning transmission electron microscopy (STEM) (1)
- Scarf joint repair (1)
- Schadensprävention (1)
- Schwerelosigkeit (1)
- Schwingbrüche (1)
- Schwingstreifen (1)
- Screen printing (1)
- Selective laser melting (1)
- Semantic Data (1)
- Semantic Interioerability (1)
- Semantic structuring (1)
- Semantic web (1)
- Semiconductor materials (1)
- Sensor (1)
- SiO2 (1)
- Sibayak (1)
- Silber (1)
- Silicatglas (1)
- Silver cluster (1)
- Silver metallization paste (1)
- Silver precipitates (1)
- Silver-glass metallization paste (1)
- Simulation of concrete (1)
- Single-Crystal (1)
- Single-crystals (1)
- Sintering atmosphere (1)
- Sintertemperatur (1)
- Sinterung (1)
- Size distribution (1)
- Slow Crack Growth (SCG) (1)
- Slow crack growth (1)
- Small-Angle X-ray Scattering (1)
- Soda-lime-silica glass (1)
- Sol-gel coating (1)
- Solar sintering (1)
- Solid solution strengthening (1)
- Space exploration (1)
- Spannungs-Dehnungs-Verhalten (1)
- Spark plasma sintering (1)
- Specific surface (1)
- Spezifische Oberfläche (1)
- Spinodal Decomposition (1)
- Split Hopkinson bar (1)
- Spring constant (1)
- Stainless steel (1)
- Stanzen (1)
- Steel (1)
- Storage (1)
- Strain rate dependence (1)
- Structure (1)
- Structured heating (1)
- Struktur (1)
- Subsurface defects (1)
- Sulfiding (1)
- Superalloy (1)
- Superalloy single crystals (1)
- Superalloys (1)
- Superaustenite steel (1)
- Supercritical/dense phase CO 2 (1)
- Superlegierungen (1)
- Surface (1)
- Surface Energy (1)
- Surface Nucleation (1)
- Surface crystallization (1)
- Surface nucleation (1)
- Symbolik (1)
- Symmetric dwell periods (1)
- Synchrotron CT (1)
- Synchrotron radiation (1)
- Synchrotronstrahlung (1)
- Syngle Crystal alloy (1)
- Synthetic air (1)
- Systematische Schadensanalysen, Prozeduren (1)
- TAHYA (1)
- TED (1)
- TMF experiments (1)
- Temperature (1)
- Temperature driven process (1)
- Temperaturschwankungen (1)
- Tempered Martensite Ferritic Steels (1)
- Tempered martensite ferritic steel (1)
- Tempered martensite ferritic steels (1)
- Tensile Properties (1)
- Tensile stress relaxation (1)
- Tensile testing (1)
- Texturation (1)
- Thermal degradation (1)
- Thermal stress (1)
- Thermische Analyse (1)
- Thermo mechanical fatigue (1)
- Thermo-mechanical fatigue (1)
- Thermo-mechanical-loading (1)
- Thermo-optical measurement (1)
- Thermoanalytical Methods (1)
- Thermoelectric generator (1)
- Thermoelectric oxide (1)
- Thermoelektrika (1)
- Thermoelektrischer Generator (1)
- Thermographie (1)
- Thermogravimetric analysis (1)
- Thermogravimetry (1)
- Thermomechanics (1)
- Thermomechanik (1)
- Thermomechanische Eigenschaften (1)
- Thermoset polymers (1)
- Thesaurus (1)
- Titanium (1)
- Tomography (1)
- Tools (1)
- Transmissionselektronenmikroskopie (1)
- Transparent ceramics (1)
- Two Photon Polymerization (1)
- Ultraschall (1)
- Umgebungsbedingter Spannungsriss (1)
- Under cyclic loading (1)
- Utilization (1)
- Utilization, and storage (CCUS) technology (1)
- VCSEL (1)
- Vacuum hot extraction (1)
- Vernetzung (1)
- Versetzungsstrukturen (1)
- Vickers hardness (1)
- Virtueller Materialdatenraum (1)
- Viscose sintering (1)
- Viskoplastisch (1)
- Wandler (1)
- Waste water (1)
- Water-based (1)
- Weibull Distribution (1)
- Weibull distribution (1)
- Welding processing influences (1)
- Werkstoffdaten (1)
- Werkstoffprüfung (1)
- Whole-chain CCS scenario (1)
- Wind energy (1)
- Wind turbine (1)
- Wind turbine blade shell structures (1)
- Withstand voltage tests (1)
- Workshop (1)
- Wärmespeicher (1)
- X-Ray Diffraction (1)
- X-ray imaging (1)
- X-ray laminography (1)
- X-ray refraction (1)
- XRM (1)
- Zugversuchsontologie (1)
- Zyklische Belastung (1)
- Zyklische R-Kurve (1)
- alumina (1)
- arbon capture (1)
- carbon steel (1)
- ceramic (1)
- ceramics (1)
- condensate (1)
- corrosion (1)
- dental (1)
- dispersion (1)
- electrochemical characterization (1)
- impurities (1)
- microstructure analysis (1)
- multi scale testing (1)
- particle size determination (1)
- pitting corrosion (1)
- sample preparation (1)
- selective laser melting (1)
- thermomechanische Beanspruchung (1)
- utilization, and storage (CCUS) technology (1)
- volume resistivity (1)
- zertifizierte Referenzmaterialien (1)
- Öffentliche Sicherheit (1)
- Überblick (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (431)
- 5.2 Metallische Hochtemperaturwerkstoffe (115)
- 5.1 Mikrostruktur Design und Degradation (112)
- 5.4 Multimateriale Fertigungsprozesse (101)
- 5.3 Polymere Verbundwerkstoffe (52)
- 5.6 Glas (51)
- 8 Zerstörungsfreie Prüfung (46)
- 5.5 Materialmodellierung (45)
- 9 Komponentensicherheit (44)
- 8.5 Röntgenbildgebung (35)
Eingeladener Vortrag
- nein (431) (entfernen)
Substitution of lead oxide in low-melting glasses, e.g., for application in silver metallization pastes, is a current research goal. This work is focused on the investigation of silver diffusion in alkali zinc borate glasses (X2O-ZnO-B2O3, X = Li, Na, K, Rb). In addition, the redox state of silver (Ag) and thus the type of diffusing silver species were studied. For this purpose, a metallic silver coating was applied on glass cubes by means of sputtering. Heat treatment of the samples was performed close to the glass transition temperatures at 470 °C for 2 h under air and nitrogen atmosphere. Coating thickness was 1.8 µm after heat treatment, measured by a white light interferometer.
Silver diffusion profiles were measured by means of secondary neutral mass spectrometry. The silver diffusion coefficients are in the range of ~10-14 cm2/s and indicate no significant differences depending on the type of alkali ions in the glass. Dissolved Ag+-ions and [Agm]n+-clusters in the glasses were differentiated using fluorescence spectroscopy.
Precipitated metallic silver particles in the sodium containing glass were observed by means of transmission electron microcopy. Their mean particle diameter was ~6 nm.
Towards Interoperability: Digital Representation of a Material Specific Characterization Method
(2022)
Certain metallic materials gain better mechanical properties through controlled heat treatments. For example, in age-hardenable aluminum alloys, the strengthening mechanism is based on the controlled formation of nanometer sized precipitates, which represent obstacles to dislocation movement. Precise tuning of the material structure is critical for optimal mechanical behavior in the application. Therefore, analysis of the microstructure and especially the precipitates is essential to determine the ideal parameters for the interplay of material and heat treatment. Transmission electron microscopy (TEM) is utilized to identify precipitate types and orientations in a first step. Dark-field imaging (DF-TEM) is often used to image the precipitates and to quantify their relevant dimensions.
The present work aims at the digital representation of this material-specific characterization method. Instead of a time-consuming, manual image analysis, an automatable, digital approach is demonstrated. Based on DF-TEM images of different precipitation states of a wrought aluminum alloy, a modularizable digital workflow for quantitative precipitation analysis is presented. The integration of this workflow into a data pipeline concept will also be discussed. Thus, by using ontologies, the raw image data, their respective contextual information, and the resulting output data from the quantitative precipitation analysis can be linked in a triplestore. Publishing the digital workflow and the ontologies will ensure the reproducibility of the data. In addition, the semantic structure enables data sharing and reuse for other applications and purposes, demonstrating interoperability.
The presented work is part of two digitization initiatives, the Platform MaterialDigital (PMD, materialdigital.de) and Materials-open-Laboratory (Mat-o-Lab).
Ontologies that represent a map of the concepts and relationships between them, are becoming an effective solution for data standardization and integration of different resources in the field of materials science, as efficient data storage and management is the building block of material digitization. However, building a domain ontology is not a simple task. It requires not only a collaborative effort between ontologists and domain experts, but also the modeling approaches and tools play a key role in the process. Among all approaches, graphical representation of domain ontologies based on standard conceptual modeling languages is widely used because of its intuitiveness and simplicity. Various tools have been developed to realize this approach in an intuitive way, such as Protégé plugins and web visualization tools.
The Materials-open-Lab (MatOLab) project, which aims to develop ontologies and workflows in accordance with testing standards for the materials science and engineering domains, adopted a UML (Unified Modeling Language) approach based on the diagrams.net. It is a powerful, popular, open-source graphical editor. In practical case studies, however, many users’ needs could not be met, such as reusing ontology, conversion, and data mapping. Users must switch between different tools to achieve a certain step, and thereby invariably increase learning cost. The lack of validation also leads to incorrect diagrams and results for users who are not familiar with the ontology rules. To address these issues, we designed Ontopanel, a diagrams.net-based plugin that includes a set of pipeline tools for semantic modeling: importing and displaying protégé-like ontologies, converting diagrams to OWL, validating diagrams by OWL rules, and mapping data. It uses diagrams.net as the front-end for method modeling and Django as the back-end for data processing. As a web-based tool, it is very easy to expand its functionality to meet changing practical needs.
Following the new paradigm of materials development, design and optimization, the digitalization of materials and processes is the main goal which imposes a huge challenge. In this respect, the quality assurance of processes and output data as well as the interoperability between applications following FAIR (findability, accessibility, interoperability, reusability) principles are to be ensured. This includes storage, processing and querying of data in a preferably standardized form, also addressing the incorporation of standardization bodies. To meet the challenge to contextualize material data in a way that is consistent with all stakeholders, all necessary information on the condition of the material including production and application-related changes have to be made available via a uniform, machine-readable description. For this purpose, ontologies are to be used since they allow for machine-understandable knowledge representations and semantic conceptualizations that are needed for data management and the digitalization in the field of materials science.
With respect to this currently ever-growing topic of integration and reuse of data and knowledge from synthesis, production and characterization of materials, this presentation shows the efforts taken within the project Platform MaterialDigital (PMD, materialdigital.de) to store tensile test data in accordance with a standard-compliant ontological representation. The includes the path from developing an ontology in accordance with the respective standard, converting ordinary and arbitrarily selected data gained from standard tests into the interoperable RDF format, up to connecting the ontology and data, respectively. Finally, such data can be queried from a triple store.
In the field of material science and engineering (MSE), most mechanical test methods are standardized which serves as a valid basis for ontology development. Therefore, the well-known tensile test of metals at room temperature (DIN EN ISO standard 6892-1:2019-11) was selected to be considered as one of the first use cases in PMD. This consideration within the PMD features both, the ontological representation of such a tensile test in accordance with the standard as well as exemplary data generation. The semantic connection of the ontology and data leads to interoperability and an enhanced ability of querying.
Silber-Glas Wechselwirkungen spielen eine wichtige Rolle zum Beispiel in Glas-haltigen Silberpasten, die in der Photovoltaik oder Mikroelektronik verwendet werden. Um ein besseres Verständnis der Vorgänge zu erhalten, werden niedrig-schmelzende, bleifreie X2O ZnO B2O3 Gläser (X = Li, Na, K und Rb, Abk.: LZB, NZB, KZB and RZB) zur Untersuchung der Pasten verwendet.
Raman und Infrarot Spektroskopie zeigen, dass die Glasstruktur weitgehend vergleichbar ist, aber Unterschiede in der Bildung von Pentaboratgruppen in LZB und NZB oder Diboratgruppen in KZB und RZB auftreten. Die Anzahl an vierfach koordinierten Bor-Ionen (N4) sinkt mit zunehmendem Alkaliionenradius. Die Verringerung von N4 führt zu einer niedrigeren Glasübergangstemperatur in der Reihe LZB (472 °C) < NZB (465 °C) < KZB (460 °C) < RZB (449 °C).
Zur Herstellung der Pasten wurde kommerzielles Silber-Pulver mit 30 Vol.-% Glas und Organik gemischt. Das Sinterverhalten der gepressten Pulver wurde mittels Erhitzungsmikrospie untersucht. Der Sinterbeginn der Pasten ist vergleichbar und korrespondiert mit den geringen Unterschieden der Viskosität bei vergleichbarer Partikelgröße der Gläser. In den Ag-KZB- und Ag-RZB-Pasten ist die Schwindung durch die stärker einsetzende Kristallisation im Vergleich zu LZB und NZB verzögert.
The mechanical strength of wrought high-strength aluminum alloys is essentially based on precipitation hardening, possibly in combination with prior forming, e. g. by stretching. Important parameters for achieving an optimum combination of hardness, strength, ductility, toughness, and further properties such as corrosion resistance are age-hardening temperature and time.
During thermal (mechanical) treatment, nucleation and growth of precipitates takes place, leading to the desired degree of hardening. In aluminum alloys, precipitation sequences are usually passed through, i. e. a sequence of metastable precipitates is formed before the stable phase can precipitate. The optimum combination of properties is therefore based on a certain (optimum) microstructure, which can, however, change during the use of a component, since the microstructure is not stable. This happens in particular when the operating temperatures are close to the aging temperature and/or the operating times are sufficiently long. An external mechanical load may accelerate the processes. The presentation gives some examples for this.
The presentation shows the results of high cycle fatigue (HCF) tests from the aluminium alloy EN AW-2618A. This study investigates the mean stress influence in the T61 condition and the effect of overaging. For this purpose, axial HCF tests were carried out at room temperature and different stress ratios (R=-1, R=0.1) as well as with overaged conditions (T61+10h@230°C, T61+1000h@230°C). After completion of the tests, the fracture surfaces were examined to study crack initiation.
Der Vortrag gibt einen Überblick über die Materialklasse Keramik, insbesondere Technische Keramik. Nach einem kurzen Überblick über typische Anwendungen und Werkstoffe wird die keramische Prozesskette erläutert. Am Beispiel von Festigkeit wird der für Keramik typische, enge Zusammenhang zwischen Technologie, Mikrostruktur und Eigenschaften herausgearbeitet. Daraus werden Anforderungen für eine erfolgreiche Digitalisierung abgeleitet.
Entwicklung der Mikrostruktur der mechanischen Eigenschaften und der Eigenspannungen in L-PBF 316L
(2022)
Die additive Fertigung (AM) metallischer Werkstoffe mittels Laser Powder Bed Fusion (L-PBF) ermöglicht einzigartige hierarchische Mikrostrukturen, die zu Verbesserungen bestimmter mechanischer Eigenschaften gegenüber konventionell hergestellten Varianten derselben Legierung führen können. Allerdings ist das L-PBF-Verfahren häufig durch das Vorhandensein hoher Eigenspannungen gekennzeichnet, die es zu verstehen und zu mindern gilt. Daher ist das Verständnis der Mikrostrukturen, der Eigenspannungen und der daraus resultierenden mechanischen Eigenschaften entscheidend für eine breite Akzeptanz bei sicherheitskritischen Anwendungen. Die BAM hat ein multidisziplinäres Forschungsprogramm gestartet, um diese Aspekte bei LPBF 316L zu untersuchen. Der vorliegende Beitrag stellt einige der wichtigsten Ergebnisse vor: der Einfluss von Prozessparametern auf die Mikrostruktur, der Einfluss von Mikrostruktur und Textur auf die Festigkeit, Kriechverhalten und Schädigung und die Stabilität von Eigenspannungen und Mikrostruktur unter Wärmebehandlungsbedingungen.
Liquid phase sintering of glass bearing silver pastes used in photovoltaics and microelectronics is poorly understood. In particular, the role of different network modifiers acting in the glass component and the question of the most suitable atmospheric oxygen level during sintering are still under considerable debate. To tackle these issues, low-melting and lead-free X2O-ZnO-B2O3 glasses with X = Li, Na, K and Rb (LZB, NZB, KZB and RZB) were prepared. Infrared spectroscopy showed that the glass structure was similar to each other, while an increase of tetrahedrally coordinated boron with increasing field strength of the alkali was evident. In turn, the glass transition temperature (from differential thermal analysis) increased in the order: RZB (449 °C) < KZB (460 °C) < NZB (465 °C) < LZB (472 °C). Powders of each glass were mixed with organics to receive silver-glass-pastes containing 30 vol% glass and these were subjected to heating microscopy in air. Although similar onset temperatures of sintering were recorded for Ag-NZB and Ag-LZB glass pastes, and for Ag-RZB paste and KZB-Ag-paste, respectively, differences in the crystallization behavior and final densification were observed between the former and the latter group. These were translated in terms of differences in silver dissolution and reprecipitation among the two groups. Further, running the experiments in nitrogen gas showed that sintering of all pastes was considerably hampered. The slow-down of the sinter kinetics was found to be in line with the assumed lower oxidation and dissolution of silver ions into the glass-forming liquid.
Fully-reversed fatigue behavior of scarf joint repairs for wind turbine blade shell applications
(2022)
Due to manufacturing imperfections which can propagate to damage under in-service loads, wind turbine rotor blades, made primarily of glass fiber reinforced polymers (GFRP), often fail significantly before their design life. To enable a quick and cost-effective return to service, localized repairs can be executed by technicians in the field, directly accessing the blades by suspended roping. Scarf joint repairs, shown to be highly efficient with a smooth load transition across angled joint walls and a restored aerodynamic profile, are the focus of this study. The damage mechanisms of these structures were examined under fully-reversed mechanical cyclic loading with a load ratio R = -1, which was made possible on the coupon scale by a custom designed anti-buckling support. The number of cycles to failure were compared across load levels. While the scarf joint ratio was held constant at 1:50, known from industry and literature to be a good compromise between restored mechanical properties and repair size, the layup sequence was varied between small-to-large and large-to-small. Hereby the effect of the presence of resin pockets and fiber orientation mismatch between the parent and repair structure on the failure mechanism as well as fatigue strength of ±45° GFRP scarf joint repair structures was studied. Strain development across the joint length was measured to assess stiffness degradation in addition to the fatigue strength recovery of scarf joint structures with respect to pristine reference specimens. Grayscale analysis was used to monitor the damage state leading to fracture across the specimens. Post-mortem fractography analysis with light microscopy described the global failure mechanisms as well as local damage distribution within the structure, all of which provided insight to critical variables in scarf joint GFRP structures under fully-reversed mechanical cyclic loading, allowing for the tailoring of such repairs on wind turbine blade shells for maximum restoration of service life.
To reveal the corrosion resistance of casing steel/mortar interface in CO2 injection condition, sandwich samples were prepared and exposed up to 20 weeks in aquifer fluid under 10 MPa and 60 °C.
Cross section analysis revealed the crevice corrosion as main mechanism instead of pitting corrosion despite very high concentration of Cl in NGB.
EDS element line scan analysis of the 20-week-exposed metal/mortar coupon showed Chloride distribution, which still not reached the metal/mortar interface, explaining no pitting was observed.
It was confirmed that FeCO3 cannot protect the steel surface in CO2 saturated NGB.
To verify the protective possibility of passivation happened on casing steel/mortar interface, simulated pore solution was synthesized and used to passivate the steel for 42 days. OCP and EIS confirmed the formation of passive layer.
The 42 day passivated layer was broken during the first minute of exposure in CO2 saturated NGB.
However, due to high concentration of Ca2+, a new carbonate CaCO3 dense layer was formed, increased the corrosion resistance of steel surface.
Powder bed technologies are amongst the most successful Additive Manufacturing (AM) techniques. Powder bed fusion and binder jetting especially are leading AM technologies for metals and polymers, thanks to their high productivity and scalability.
The application of these techniques to most ceramics has been difficult so far, because of the challenges related to the deposition of homogeneous powder layers when using fine powders.
In this context, the "layerwise slurry deposition" (LSD) has been developed as a layer deposition method which enables the use of powder bed AM technologies also for advanced ceramic materials. The layerwise slurry deposition consists of the layer-by-layer deposition of a ceramic slurry by means of a doctor blade, in which the slurry is deposited and dried to achieve a highly packed powder layer. This offers high flexibility in the ceramic feedstock used, especially concerning material and particle size.
The LSD technology can be combined with binder jetting to develop the so-called “LSDprint” process for the additive manufacturing of ceramics.
The LSDprint technology combines the high-speed printing of binder jetting with the possibility of producing a variety of high-quality ceramics with properties comparable to those achieved by traditional processing.
In this presentation, the LSD process will be introduced and several examples of application ranging from silicate to high-performance ceramics will be shown.
Recent developments towards the scale-up and industrialization of this process will be discussed, alongside future perspectives for the multi-material additive manufacturing.
Spurenelemente spielen eine wichtige Rolle bei der Verfeinerung der Eigenschaften von komplexen Materialien. Diese Arbeit zeigt die Korrelation zwischen der Mikrostruktur, der Gitterfehlpassung und den Kriecheigenschaften. Die Legierung Al10Co25Cr8Fe15Ni36Ti6 (in at. %) mit komplexer Zusammensetzung wurde mit den Elementen Hf und W verstärkt. Die Zugabe von Hf bewirkt eine eckigere Form der würfelförmigen gamma'-Ausscheidungen und einen erhöhten Anteil der Heusler-Phase. Die Zugabe von W wiederum formt die Würfelchen rundlicher und löst die Heusler-Phase auf. Eine Mischung der beiden Spurenelemente zeigt einen Übergang zwischen den beiden Extremen, sowohl in Hinsicht auf die Form der Ausscheidungen als auch in Bezug auf die Gitterfehlpassung und die Kriecheigenschaften.
Early Material Damage in Equimolar CrMnFeCoNi in Mixed Oxidizing/Sulfiding Hot Gas Atmosphere
(2022)
The challenges to use more varied fuels at medium and high temperatures above 500 °C need to be addressed by tuning the materials towards a better resistance against increased corrosion. As a first step the corrosion processes need to be better understood, especially in the case of the unavoidable and highly corrosive sulfur-based gases. In this work oxidation/sulfidation of an equimolar CrMnFeCoNi high entropy alloy is studied at an early stage after hot gas exposure at 600 °C for 6 h in 0.5% SO2 and 99.5% Ar. The oxidation process is studied by means of x-ray diffraction, scanning and transmission electron microscopy and supported by thermodynamic calculations. It is found that the sulfur does not enter the bulk material but interacts mainly with the fast-diffusing manganese at grain boundary triple junctions at the alloy surface. Sub-micrometer scaled Cr-S-O rich phases close to the grain boundaries complete the sulfur-based phase formation. The grains are covered in different Fe, Mn and Cr based spinels and other oxides.
Thermoelectric generators can be used for energy harvesting by directly transforming a temperature gradient into a voltage. Multilayer generators based on ceramic multilayer technology are an interesting alternative to conventional π-type generators. They exhibit several advantages like high filling factor, possibility of texturing, co-firing of all materials in one single-step, and reduction of production costs due to the high possible degree of automation. But, co-firing of promising oxide thermoelectric materials, Ca3Co4O9 (p-type) and CaMnO3 (n-type), is very challenging due to the large difference in sintering temperature (300 K).
In this work we show the material development of Ca3Co4O9, CaMnO3, and insulation for multilayer generators co-fired under uniaxial pressure at 900 °C. The materials are tailored regarding their sintering behavior, electrical performance and coefficients of thermal expansion. Tape-casting and pressure assisted sintering are applied to fabricate textured Ca3Co4O9. Compared to conventional sintering, pressure assisted sintering increases the strength by the factor 10 and the power factor by the factor of 20. The combination of sintering additives and uniaxial pressure is used to decrease the sintering temperature of CaMnO3 to 900 °C while maintaining acceptable thermoelectric properties.
Different generator designs (unileg and pn-type) were fabricated and analyzed regarding microstructure and thermoelectric performance. A lower level of complexity is beneficial for co-firing and performance. The unileg demonstrators reach 80% of the simulated output power and the power output is highly reproducible between the different demonstrators (99%).
Turbine blades often contain cylindric holes used to generate an air film that protects the blade alloy from the hot gases. These cooling holes of diameter around one mm are drilled by laser through the thickness of the blades. Unfortunately, the resulting stress concentration and the drilling-induced damage are known to favor crack initiation from the holes. It is thus necessary to assess the impact of these cooling holes on the structural integrity of the blades. Since cracks initiate very readily, the fatigue life of the components is mainly controlled by the propagation of the cracks in the stress gradient induced by the holes.
For this purpose, displacement controlled high-temperature LCF (Low-Cycle-Fatigue) tests were performed with center hole specimens of a coarse-grained Nickel base Superalloy. The tests were stopped after a defined load drop. In addition, crack propagation tests with Double Edge Notch specimens were performed. Moreover, specimens with different hole surface finishes were investigated, which showed a detrimental effect of the hole surface roughness. In parallel, an evaluation of the LCF tests based on a fracture mechanics-based model (Madia et al., Eng. Fract. Mech., 2018) has been applied. Thereby, the specimen life is controlled by the crack propagation time until failure. Crack growth is controlled by a modified NASGRO equation accounting for large-scale yielding and a progressive build-up of crack closure. The initial crack size has been derived from the measurements of defects around the borehole. A reasonable agreement between predicted and measured lifetimes is observed if one keeps in mind the large uncertainty regarding the effective shape of the cracks.
Thermal spraying provides a rapid method for additive deposition of various ceramics as electrical insulation in applications where polymers are not suitable. New applications in complex shaped additive manufactured metal parts are emerging for example in large scale electrical devices. Microstructural and dielectric evaluation of coatings is crucial to the employment of such free-form processes. The properties and microstructure of the plasma sprayed alumina coatings are compared with dense reference samples of the same powder produced by spark plasma sintering (SPS). To obtain dense bulk samples from the coarse alumina powder for spray coating, SPS is used.
Samples are fabricated by atmospheric plasma spraying (APS) of commercially available alumina powder (d50 = 33 µm) on copper substrates and by SPS of the same powder. Microstructure and porosity were analyzed by optical microscopy and scanning electron microscopy (SEM). Phase compositions were determined by X-ray diffraction (XRD). Dielectric properties such as DC resistance, dielectric strength, dielectric loss, and relative permittivity were determined according to the standards. The microstructure and dielectric properties of the coating and bulk material are compared to assess whether the coating is suitable for use in electrical insulation application.
The scatter of fatigue crack growth data can become significant for coarse grained materials. By using a probabilistic description of crack propagation as the foundation of a lifetime prediction model, lifetime scatter of laboratory specimens can be reproduced. However, the lifetime of real components is subjected to additional scattering factors such as surface condition or uncertainty regarding direction and shape of emerging cracks. These factors need to be addressed in order to exploit the advantages of probabilistic description, i.e. the reduction of unnecessary conservatisms.
High temperature LCF (Low-Cycle-Fatigue) tests were performed with center hole specimens of a coarse-grained Nickel base Superalloy. In addition, crack propagation tests with Double Edge Notch specimens were performed. A procedure to detect the shape of the starting crack that combines the potential drop method and induction thermography was developed. The geometry and the number of notches were varied. Moreover, specimen with different hole surface finishes were investigated, which showed a detrimental effect of the roughness of the hole surface.
The results have been compared to predictions of a probabilistic tool for the estimation of lcf lifetime that has been calibrated beforehand on laboratory specimens with and without notches. In parallel, a fracture mechanics-based lifetime model was developed, which includes the initial crack size as a critical parameter. Thereby, the influence of the large grain size (>1mm), and the shape of the starting crack at the notch were considered.
Acknowledgements
The investigations are conducted as part of the joint research program COOREFLEX-Turbo in the frame of AG Turbo. The work is supported by Siemens AG and the Bundesministerium für Wirtschaft und Technologie (BMWi) as per resolution of the German Federal Parliament under grant number 03ET7071E.
Dielectric breakdown of insulators is a combined electrical, thermal, and mechanical failure. The exact breakdown mechanism in ceramics and the formulation of useful models are still subject of investigation. Recent studies highlighted that several experimental aspects of dielectric breakdown strength testing affect the test results, and thus impede the recognition of fundamental principles.
Excess field strength near the electrode can lead to premature breakdown in the insulating liquid. This would cause superficial damage to the test specimen and thus falsify the measurement results.
The field strength distribution is influenced by the ratio of permittivity of the sample and the surrounding insulating liquid. Premature breakdown depends on the breakdown strength of the liquid and the actual test voltage. The test voltage again depends on the specimen thickness.
To systematically investigate these relations, a numerical simulation study (FEM) of the electric field distribution in a typical testing rig with cylindrical electrodes was performed. The permittivity of the sample and the insulating liquid was parameterized, as well as the sample thickness. The electric field distribution was calculated for increasing test voltage. Field strength maxima are compared to experimental breakdown strength of typical insulating liquids and experimental breakdown locations on alumina. Strategies are discussed to adjust the insulation liquid and the sample thickness to reduce the influence of the testing setup on the dielectric breakdown strength results.