Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
- 2020 (615) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (311)
- Vortrag (169)
- Beitrag zu einem Tagungsband (35)
- Posterpräsentation (28)
- Sonstiges (25)
- Beitrag zu einem Sammelband (12)
- Forschungsdatensatz (8)
- Buchkapitel (6)
- Zeitschriftenheft (Herausgeberschaft für das komplette Heft) (6)
- Forschungsbericht (5)
Sprache
- Englisch (497)
- Deutsch (112)
- Mehrsprachig (3)
- Spanisch (2)
- Russisch (1)
Schlagworte
- Nanoparticles (39)
- Additive manufacturing (22)
- Korrosion (20)
- Corrosion (17)
- Fluorescence (17)
- Laser beam welding (15)
- Microstructure (15)
- Nanoparticle (15)
- Electron microscopy (14)
- Lifetime (14)
- Quantum yield (14)
- Additive Manufacturing (12)
- Dye (11)
- SAXS (11)
- Nano (10)
- Particle size distribution (10)
- Photoluminescence (10)
- Photophysics (10)
- Sensor (10)
- Welding (10)
- XPS (10)
- Computed tomography (9)
- Laser-induced periodic surface structures (LIPSS) (9)
- Nanomaterials (9)
- Quality assurance (9)
- Thermography (9)
- Coating (8)
- Mechanical properties (8)
- Mechanochemistry (8)
- Residual stress (8)
- X-ray diffraction (8)
- Additive Fertigung (7)
- Applications (7)
- Durability (7)
- EBSD (7)
- Lanthanide (7)
- Method (7)
- NIR (7)
- Nanomaterial (7)
- Particle (7)
- Porosity (7)
- Small angle scattering (7)
- Surface chemistry (7)
- X-ray refraction (7)
- Electrochemistry (6)
- Laser powder bed fusion (6)
- Laser processing (6)
- Measurement uncertainty (6)
- Quantification (6)
- Reference materials (6)
- Sample preparation (6)
- Simulation (6)
- Synthesis (6)
- TED-GC/MS (6)
- Upconversion (6)
- Wear (6)
- Zink (6)
- 316L (5)
- AFM (5)
- Degradation (5)
- Digitalisierung (5)
- High entropy alloys (5)
- Hot cracking (5)
- Laser Powder Bed Fusion (5)
- Laserstrahlschweißen (5)
- Nanocomposite (5)
- Nanostructures (5)
- Normung (5)
- Surface functionalization (5)
- TEM (5)
- Ti-6Al-4V (5)
- Tribology (5)
- UHPC (5)
- VAMAS (5)
- Wasserstoff (5)
- XANES (5)
- Aktivkohle (4)
- Aluminium (4)
- Architectural Concrete (4)
- Biofilm (4)
- Concrete (4)
- Crystal (4)
- Deckschichtbildung (4)
- Diffraction (4)
- Facade Elements (4)
- Geant4 (4)
- Gold (4)
- High-entropy alloy (4)
- Hydrogen (4)
- In-situ Monitoring (4)
- Korrosionsprüfung (4)
- LTCC (4)
- MCS (4)
- Machine learning (4)
- Microbiologically influenced corrosion (4)
- Microscopy (4)
- Microstructures (4)
- NanoDefine (4)
- Nanomaterial classification (4)
- Neutron diffraction (4)
- Oxygen evolution reaction (4)
- Polymer (4)
- Post weld heat treatment (4)
- Process monitoring (4)
- SEM (4)
- Scattering (4)
- Schweißen (4)
- Self-Cleaning Properties (4)
- Shape (4)
- Size (4)
- Small-angle X-ray scattering (4)
- Solidification cracking (4)
- Standardisation (4)
- Surface modification (4)
- Synchrotron (4)
- Traceability (4)
- AIE (3)
- Adsorption (3)
- Ageing (3)
- Aggregation (3)
- Aggregation-induced emission (3)
- Aging (3)
- AlSi10Mg (3)
- Alterung (3)
- Ammonium nitrate (3)
- Anerkennungen (3)
- Archaeometry (3)
- Artificial neural networks (3)
- Atmosphärische Korrosion (3)
- Automation (3)
- Betonfahrbahndecken (3)
- CCUS (3)
- Calcium sulfate (3)
- Carbon Fiber Reinforced Plastics (3)
- Ceramics (3)
- Crack evolution (3)
- Creep-resistant steel (3)
- Crevice corrosion (3)
- Data processing (3)
- Diffraction Enhanced Imaging (3)
- Diffusion (3)
- EBSD analysis (3)
- EXAFS (3)
- Element transport (3)
- Enhancement (3)
- Explosives (3)
- Fatigue (3)
- Festlegungen (3)
- Fluorescence standard (3)
- Forschungsdatenmanagement (3)
- Geant4-DNA (3)
- Geothermal (3)
- Grinding (3)
- High entropy alloy (3)
- High-pressure (3)
- High-strength steel (3)
- Hochfester Feinkornbaustahl (3)
- Hochfester Stahl (3)
- Hybrid laser-arc welding (3)
- Imaging (3)
- In situ tensile test (3)
- Inter-laboratory comparison (3)
- Intrinsischer Schwellenwert gegen Ermüdungsrissausbreitung (3)
- Kaltriss (3)
- Kriechen (3)
- Laser implantation (3)
- Laser metal deposition (3)
- Laser powder bed fusion (L-PBF) (3)
- Linearity (3)
- MAG-Schweißen (3)
- MSG-Schweißen (3)
- Machine Learning (3)
- Method development (3)
- Monte-Carlo simulations (3)
- Nano particle (3)
- Non-destructive characterisation (3)
- Numerical modelling (3)
- Numerical simulation (3)
- O-ring (3)
- Online NMR spectroscopy (3)
- Open data (3)
- Open science (3)
- Particle scattering simulations (3)
- Particle size (3)
- Polarity (3)
- Polymers (3)
- Prill (3)
- Process industry (3)
- Real-time process monitoring (3)
- Reproducibility (3)
- Residual Stress (3)
- Restlebensdauer (3)
- Rheology (3)
- Richtlinien (3)
- Risk assessment (3)
- SOP (3)
- SWIR (3)
- Selective laser melting (SLM) (3)
- Single particle (3)
- Single-source precursors (3)
- Solid state emission (3)
- Specific surface area (3)
- Stainless steel (3)
- Standardization (3)
- Stress relief cracking (3)
- Surface (3)
- Surface chemical analysis (3)
- Thermal treatment (3)
- TiO2 (3)
- Topas (3)
- Transmission electron microscopy (3)
- Tribologie (3)
- Ultrasound (3)
- Upconversion nanoparticle (3)
- X-ray scattering (3)
- Zonation (3)
- Zulassungen (3)
- 3D (2)
- 3D printing (2)
- AISI 316L (2)
- AM (2)
- ANFO (2)
- Absorption (2)
- Additiv gefertigter Stahl (2)
- Adhesive Pull-Strength (2)
- Adhesive strength (2)
- Aluminum alloys (2)
- Anisotropy (2)
- Artungleiche Werkstoffe (2)
- Assay (2)
- Atomic force microscopy (2)
- Auftragschweißen (2)
- Automated analysis (2)
- Automatisation (2)
- BDS (2)
- Bacteria (2)
- Bacterial adhesion (2)
- Bead (2)
- Biobrennstoff (2)
- Boehmite (2)
- Brightness (2)
- Bulge effect (2)
- Cancer (2)
- Capability (2)
- Carbon steel (2)
- Case studies (2)
- Catalysis (2)
- Cement (2)
- Cementitious materials (2)
- Characterization (2)
- Circumferential weld (2)
- Cocrystal (2)
- Coda Wave Interferometry (2)
- Complex oxides (2)
- Composite (2)
- Composition (2)
- Compositionally complex alloys (2)
- Compression Set (2)
- Compression set (2)
- Computed Tomography (2)
- Computertomographie (2)
- Condensed Matter Physics (2)
- Convolutional neural networks (2)
- Core-shell (2)
- Correlative ex-situ ellipsometric analysis (2)
- Corrosion resistance (2)
- Cr(III) (2)
- Creep (2)
- Cryogenic steel (2)
- Crystal structure (2)
- Crystallization (2)
- Deep penetration (2)
- Desintegracion radioactiva (2)
- Diffusible hydrogen (2)
- Digestion (2)
- Duplex (2)
- EC4SafeNano (2)
- EDS (2)
- EMPIR 18HLT01 MetVesII (2)
- EPDM (2)
- Eigenspannungen (2)
- Elastomer (2)
- Electron backscatter diffraction (2)
- Electron beam melting (2)
- Elektromagnetische Schmelzbadbeeinflussung (2)
- Ellipsometric operando investigation (2)
- End crater (2)
- Endkrater (2)
- Energy Engineering and Power Technology (2)
- Energy harvesting (2)
- Expansion joint (2)
- Extracellular vesicles (EV) (2)
- Extrusion (2)
- FAME (2)
- FEM (2)
- FIB (2)
- FTIR (2)
- Far-infrared spectroscopy (2)
- Faseroptische Sensorik (2)
- Fatigue strength (2)
- Femtosecond laser ablation (2)
- Fibres (2)
- Filler material distribution (2)
- Finite element method (2)
- Flame retardant (2)
- Flow cytometry (FCM) (2)
- Fluorescent particles (2)
- Fluoride (2)
- Fracture mechanics (2)
- Friction (2)
- Fuel Technology (2)
- Functionalization (2)
- Fügetechnologie (2)
- Gefahrgutregeln (2)
- Gelartige Elektrolyte (2)
- Glass (2)
- Glass transition (2)
- Grafting (2)
- Graphene (2)
- Graphene oxide (2)
- HIP (2)
- HR-CS-AAS (2)
- Hardness (2)
- Heizöl (2)
- High Entropy Alloy (2)
- High Entropy Alloys (2)
- High temperature corrosion (2)
- Hot stamping (2)
- Hydrogen economy (2)
- Hydrogen-assisted cracking (2)
- Hydrothermal treatment (2)
- ICP-OES (2)
- Image analysis (2)
- Image segmentation (2)
- Imaging XPS (2)
- Implant test (2)
- In-situ (2)
- Infrared thermography (2)
- Ink analysis (2)
- Integrating sphere spectroscopy (2)
- Interdisciplinary approach (2)
- Interfaces (2)
- Interlaboratory test (2)
- Iron (2)
- Iron oxide nanoparticles (2)
- Isotope analysis (2)
- Joint sealing (2)
- Kontrastierung (2)
- Korrosionswechselprüfung (2)
- L-PBF (2)
- LC-MS (2)
- LMD (2)
- LPBF (2)
- LTT weld filler materials (2)
- Laser (2)
- Laser metal deposition (LMD) (2)
- Laser-Pulver-Auftragschweißen (2)
- Laserhybridschweißen (2)
- Ligand (2)
- Lining (2)
- Lithium batteries (2)
- Load transfer (2)
- Localized laser dispersing (2)
- MALDI-TOF MS (2)
- Machining (2)
- Mass spectrometry (2)
- Matching ferritic welding electrode (2)
- Materialbearbeitung (2)
- Materials science (2)
- Mechanical mismatching (2)
- Mechanism (2)
- Medium Entropy Alloys (2)
- Mesoporous iridium oxides films (2)
- Metal matrix composite (2)
- Methanogen (2)
- Metrology (2)
- Microplastic (2)
- Microprinting (2)
- Microstructure-property relations (2)
- Mikroplastik (2)
- Mikroplastik-Massengehalte (2)
- Modeling (2)
- Modelling (2)
- Multiplexing (2)
- Método de Montecarlo (2)
- NMR (2)
- NMR spectroscopy (2)
- Nanocomposites (2)
- Nanosafety (2)
- Nanostructure (2)
- Nanotechnology (2)
- Neutron Diffraction (2)
- Neutron imaging (2)
- Nomenklatur (2)
- Nucleation (2)
- Optische Tomografie (2)
- PDF (2)
- Particle scattering simulation (2)
- Penetration depth (2)
- Peptide (2)
- Performance testing (2)
- Permethrin (2)
- Phase transition (2)
- Polylactide (2)
- Polymer matrix composites (2)
- Pore orientation (2)
- Preferred orientation (2)
- Präparation (2)
- Prüfverfahren (2)
- Quasicrystal (2)
- Radioactive decay (2)
- Radioactive nanoparticle (2)
- Reaction sintering (2)
- Reference material (2)
- Regulation (2)
- Renewable Energy, Sustainability and the Environment (2)
- Residual stresses (2)
- Rigid amorphous fraction (2)
- Ringversuch (2)
- Rubber (2)
- Rundnaht (2)
- SAXS/WAXS (2)
- SBA-15 (2)
- Scanning electron microscopy (2)
- Scanning kelvin probe force microscopy (2)
- Schadenstolerante Bauteilauslegung (2)
- Schmelzbadbeobachtung (2)
- Schweißnahtgeometrie (2)
- Selective laser melting (2)
- Sequential analysis (2)
- Shrinkage (2)
- Silver nanoparticle (2)
- Single crystal (2)
- Sintering additives (2)
- Software (2)
- Stability (2)
- Stahl (2)
- Stahl und Aluminium (2)
- Stainless Steel (2)
- Standards (2)
- Starch (2)
- Starch nanoparticle (2)
- Strain hardening (2)
- Strength (2)
- Stress exponent (2)
- Stress relaxation (2)
- Superlegierung (2)
- Surface area (2)
- Switch (2)
- Synchrotron Tomography (2)
- Synchrotron X-ray diffraction (2)
- TEKKEN (2)
- TMDSC (2)
- Texture (2)
- Thermal decomposition (2)
- Thermoanalytik (2)
- Thermodynamics (2)
- Thermoelectrics (2)
- Thermografie (2)
- Thermogravimetrie (2)
- Thin films (2)
- Transmission Kikuchi Diffraction (TKD) (2)
- Transport mechanism (2)
- Trinkwasser (2)
- Ultra-High Performance Concrete (2)
- Ultra-High-Performance Concrete (2)
- Ultrakurze Laserimpulse (2)
- Ultrasonic machining (2)
- Varestraint testing (2)
- Wasseraufbereitung (2)
- Weathering (2)
- Weld toe geometry (2)
- Welding thermal cycle (2)
- Werkstoffprüfung (2)
- Wood (2)
- X-ray photoelectron spectroscopy (2)
- XCT (2)
- Yb(III) complex (2)
- Zerstörungsfreie Prüfung (2)
- Zirconia (2)
- gelartige Elektrolyte (2)
- nanoparticula (2)
- μCT-analysis (2)
- 100Cr6 (1)
- 13CrMoV9-10 (1)
- 29Si (1)
- 2D (1)
- 2D chromatography (1)
- 2PP (1)
- 3D printing Polyamide 12 (1)
- 3D-Texturerfassung (1)
- 3D-printing (1)
- 89Y MAS-NMR (1)
- 9%Ni steel (1)
- A Greek palimpsest (1)
- A357-T6 cast aluminum alloy (1)
- A357-T6 casting (1)
- A4F (1)
- ACEnano (1)
- AIS (1)
- AISI 304L (1)
- AISI D2 (1)
- AKR (1)
- APTES (1)
- ATZ (1)
- Abbildende Ellipsometrie (IE) (1)
- Absolute (1)
- Acoustic Emission (AE) (1)
- Acoustic emission (1)
- Acoustic emission analysis (1)
- Adaptive remeshing (1)
- Additiv (1)
- Additive Manufacturing (AM) (1)
- Additive manufacturing (AM) (1)
- Additiver Fertigung (1)
- Adhesion (1)
- Adhesives (1)
- Adjustment calculation (1)
- Admixtures (1)
- Advanced Materials (1)
- Advanced Oxidation (1)
- Advanced calorimetry (1)
- Advanced high-strength steels (1)
- Affinity (1)
- Affinitätskonstante (1)
- Ag (1)
- Aggressive environments (1)
- Agricultural by-product (1)
- Alkali aluminosilicate glasses (1)
- Alkali-activated materials (1)
- Alkaline earth metal coordination polymers (1)
- Alloy 247 (1)
- Alloy 718 (1)
- Alloys (1)
- Alpha-tricalcium phosphate (1)
- Alumina (1)
- Alumina toughened zirconia (1)
- Aluminum hydroxide (ATH) (1)
- Amphiphilic polymer (1)
- Amplification (1)
- Amyloid (1)
- Analysis (1)
- Analysis area measurements (1)
- Angle dependency (1)
- Angle measurement (1)
- Annealing (1)
- Anodization (1)
- Antibacterial (1)
- Antibacterial polymer (1)
- Antibody (1)
- Antibody-gated indicator delivery (1)
- Antiquity (1)
- Application (1)
- Approximant (1)
- Aqueous quantum dot (1)
- Arrhenius (1)
- Artificial digestion (1)
- Artificial neural network (1)
- Artificial neural network modelling (1)
- Asphalt (1)
- Atmosphäre (1)
- Atom probe tomography (1)
- Atomic Forc Microscopy (1)
- Au (1)
- Au-nanocubes (1)
- AuNP (1)
- Aufheizrate (1)
- Auger Electron Spectroscopy (1)
- Auslagerungsversuche (1)
- Austenitic stainless steel (1)
- Austenitic stainless steels (1)
- Austenitic welding electrode (1)
- Autocorrelation function (1)
- Aza-BODIPY (1)
- BAMline (1)
- BET (1)
- BMDK (1)
- BODIPY (1)
- Backlight (1)
- Bacterial attachment (1)
- Bacterial second messenger (1)
- Bakterien (1)
- Bankia sp (1)
- Barcoding (1)
- Basic oxygen furnace slag (1)
- Bassanite (1)
- Batch testing (1)
- Batteries (1)
- Bead-based assay (1)
- Beanspruchung (1)
- Bending modulus (1)
- Beständigkeitsuntersuchungen (1)
- Betonfahrbahndeckentexturen (1)
- Betriebsfestigkeit (1)
- Bimetallic noble metal nanoparticles (1)
- Bimodal (1)
- Bimodal size distribution (1)
- Binder Jetting (1)
- Bio Ceramics (1)
- Bioactive glass scaffold (1)
- Bioconjugation (1)
- Biocorrosion (1)
- Biodiesel (1)
- Biofilm growth (1)
- Biofilm quantification (1)
- Biofuel (1)
- Bioinspiration (1)
- Biomimetic surfaces (1)
- Bionic materials (1)
- Biosensors (1)
- Biozide (1)
- Bismuth (1)
- Bonding strength (1)
- Bondline (1)
- Bone marrow-derived mesenchymal stem cell (1)
- Book production (1)
- Boronic acid (1)
- Boronic acid-functionalized 2D MoS2 (1)
- Bridge (1)
- Broadband Dielectric Spectrscopy (1)
- Bruch (1)
- Byzantine manuscript (1)
- C++ (1)
- C-di-GMP (1)
- C-dot (1)
- CEN (1)
- CEN/TC 352 Nanotechnologies (1)
- CO2 pipeline transport (1)
- CO2-corrosion (1)
- CT (1)
- CUINS2 nanocrystals (1)
- Cable (1)
- Cadmium and lead remediation (1)
- Calcium cobaltite (1)
- Calcium manganate (1)
- Cancer therapy (1)
- Capillary absorption (1)
- Capillary electrophoresis (1)
- Carbon Capture (1)
- Carbon Fibre (1)
- Carbon dioxide (1)
- Carbon dioxide emissions (1)
- Carbon dot (1)
- Carbon materials (1)
- Carbon nanotubes (1)
- Carboxyl group (1)
- Catalogue of Services (CoS) (1)
- Cathodic protection (1)
- Cell (1)
- Cell-repellent surfaces (1)
- Cellulose acetate (1)
- Cellulose synthase (1)
- Cement paste (1)
- Centrifugal Adhesion Testing (CAT) (1)
- Centrifugal adhesion testing (CAT) (1)
- Ceramic matrix composite (1)
- Ceramic matrix composites (1)
- Ceramic nano particles (1)
- Ceria (1)
- Chaboche model (1)
- Characterisation (1)
- Characterization method (1)
- Charge (1)
- Charge density (1)
- Chemical composition (1)
- Chemical processes (1)
- Chemischer Angriff (1)
- Chemisorption (1)
- Chemistry (1)
- Chloridinduzierte Lochkorrosion (1)
- Chromia (1)
- Chrystal orientation (1)
- Chunky graphite degeneration (1)
- Classification (1)
- Clay ISRU (1)
- Clustering (1)
- Cmake (1)
- Coaggregation (1)
- Coatings (1)
- Cocrystals (1)
- Codex Miscellaneus (1)
- Colloidal semiconductor nanocrystals (1)
- Columnar Liquid Crystal (1)
- Comparability (1)
- Comparison (1)
- Complementary methodology and metrology (1)
- Component assessment (1)
- Composite strength (1)
- Composite testing (1)
- Composites (1)
- Compound strength (1)
- Computed tomography (CT) (1)
- Computer vision (1)
- Computertomografie (1)
- Concentration (1)
- Concentrically braced steel frames (1)
- Cone calorimeter (1)
- Confined catalyst (1)
- Conservation (1)
- Consumer products (1)
- Contact resonance (1)
- Contour scan strategy (1)
- Controlled morphology (1)
- Cooling rate (1)
- Coordination chemistry (1)
- Coordination polymer (1)
- Coordination polymers (1)
- Copolymer (1)
- Copper (1)
- Coptic (1)
- Coptic studies (1)
- Core/shell particle (1)
- Correlation microstructure to properties (1)
- Correlative imaging (1)
- Corrosion products (1)
- Corrosion testing (1)
- Corrosivity (1)
- Covalent interactions (1)
- CrCoNi (1)
- CrMnFeCoNi (1)
- Crack (1)
- Crack initiation period (1)
- Crack propagation analysis (1)
- Cracks (1)
- Creep behavior (1)
- Creep behaviour (1)
- Creep deformation (1)
- Creep models (1)
- Creep resisting materials (1)
- Critical chloride content (1)
- Critical strain (1)
- Critical strain rate (1)
- Crosslinker (1)
- Crossreactivity (1)
- Cryogenic (1)
- Cryogenic cycling (1)
- Crystal engineering (1)
- Crystal growth velocity (1)
- Crystal orientation (1)
- Crystal plasticity (1)
- Crystal plasticity finite element modeling (CPFEM) (1)
- Crystallographic texture (1)
- Crystalstructure (1)
- Curing Monitoring (1)
- Cyclic R-Curve (1)
- Cyclic R-curve (1)
- Cyclic Voltammetry (1)
- Cyclic loading (1)
- DCB geometry (1)
- DED (1)
- DFG SPP 2005 (1)
- DFT calculation (1)
- DFT calculations of Raman spectra (1)
- DLO (1)
- Damage analysis (1)
- Damage detection (1)
- Damage mechanism (1)
- Damage repair (1)
- Dangerous goods (1)
- Data Fusion (1)
- Data corrections (1)
- Data correlation (1)
- Data curation (1)
- Data fusion (1)
- Data organization (1)
- Datenfusion (1)
- Debian (1)
- Decachlorotetrasilane (1)
- Decay kinetics (1)
- Deep learning (1)
- Defect detection (1)
- Definition (1)
- Defokussierung (1)
- Degradable polymer (1)
- Degradation signatures (1)
- Dehydrogenation heat treatment (1)
- Dendritic polyglycerol (1)
- Densty-based Thermodynamics (1)
- Dental materials (1)
- Depletion force (1)
- Desiccation (1)
- Design of experiment (1)
- Deuterium (1)
- Deviatoric (1)
- Die-casted aluminum (1)
- Diesel (1)
- Diesel particulates filter (1)
- Differential scanning calorimetry (1)
- Diffraction analysis (1)
- Diffraction elastic constants (1)
- Digital Detector Arrays (1)
- Digital Volume Correlation (1)
- Digital image correlation (1)
- Digitalisation (1)
- Digitalization (1)
- Dimensional accuracy (1)
- Direct laser interference patterning (1)
- Direct laser interference patterning (DLIP) (1)
- Directed Energy Deposition (1)
- Directed energy deposition (1)
- Discotic Liquid Crystals (1)
- Disinfectants (1)
- Disinfection (1)
- Dislocation density (1)
- Dislocations (1)
- Displacement (1)
- Dissimilar materials (1)
- Distortion upon baseplate removal (1)
- Distributed fiber optic sensing (1)
- Dosimetry (1)
- Double complex compound (1)
- Double notched creep specimen (1)
- Drinking water (1)
- Druckbehälter (1)
- Ductile cast iron (1)
- Duftstoffe (1)
- Duktilität (1)
- Dwell-time (1)
- Dynamic behavior (1)
- EDX (1)
- ELISA (1)
- EMPIR (1)
- EPMA (1)
- EU (1)
- Earth (1)
- Ectoine hydration (1)
- Eddy current testing (1)
- Effect of scanning strategies (1)
- Egypt (1)
- Eigenspannung (1)
- Eindringprüfung (1)
- Eisenaluminid (1)
- Elastic constants (1)
- Elastomer Dichtung (1)
- Electrical impedance (1)
- Electrocatalysis (1)
- Electrochemical impedance spectroscopy (1)
- Electrochemical treatment (1)
- Electrolysis (1)
- Electromagnetic field (1)
- Electromagnetic supported degassing (1)
- Electromagnetic theories (1)
- Electron beam cladding (1)
- Electron beam welding (1)
- Electron probe microanalysis (1)
- Electrospinning (1)
- Elektonenstrahlschweißen (1)
- Elektrochemie (1)
- Elektromagnetische Schmelzbadunterstützung (1)
- Elektronenmikroskopie (1)
- Elemental composition (1)
- Emission chamber (1)
- Emission enhancement (1)
- Emisssivity (1)
- Endothelial progenitor cell (1)
- Energy transfer (1)
- Engineered recycled mineral admixtures (1)
- Environmental Stress Cracking (ESC) (1)
- Epoxy (1)
- Epoxy Resin (1)
- Equivalent heat source (1)
- Er(III) (1)
- Ermüdung (1)
- Ermüdungsrisswachstum (1)
- Error sources analysis (1)
- Escherichia coli (1)
- Etalon feature (1)
- Etofenprox (1)
- Ettringen tuff (1)
- European Centre (1)
- European funding strategies (1)
- Exchange interaction (1)
- Experimental investigation (1)
- Explosionsgrenzen (1)
- Explosionsschutz (1)
- Explosivstoffe (1)
- FAT class approach (1)
- FAT class concept (1)
- FIB/SEM (1)
- FKM (1)
- Fab Fragment (1)
- Failure (1)
- Failure analysis (1)
- Failure pattern (1)
- False-positive results (1)
- Faserverbund (1)
- Fatigue Strength (1)
- Fatigue crack initiation (1)
- Fatigue striations (1)
- FeNi (1)
- Femtosecond laser processing (1)
- Femtosecond laser-processing (1)
- Fermi resonance (1)
- Ferrihydrite (1)
- Ferromagnetism (1)
- Festigkeit (1)
- Feuchte (1)
- Fiber optic sensors (1)
- Fiber toxicology (1)
- Fibre orientation (1)
- Fibre reinforced plastic (1)
- Fibre reinforced plastics (1)
- Field of View (1)
- Field sensor (1)
- Filler material (1)
- Filler wire (1)
- Finite Element Method (1)
- Fire following earthquake (1)
- Flammable gases (1)
- Flexible crystals (1)
- Flexural rigidity (1)
- Flow Model (1)
- Flow cytometry (1)
- Flow system (1)
- Fluorescence microscopy (1)
- Fluorescence quantum yield (1)
- Fluorescent glasses (1)
- Fluorescent probe (1)
- Fluorides (1)
- Fluorine coordination (1)
- Flüssigwasser (1)
- Force-distance curves (1)
- Forgery (1)
- Formaldehyde (1)
- Fractal (1)
- Fractional brownian motion (1)
- Fractographic observations (1)
- Fractography (1)
- Fracture Mechanics (1)
- Fracture Surface Analysis (1)
- Framework (1)
- Fre (1)
- Free polymer (1)
- Freibewitterung (1)
- Fräsbearbeitung (1)
- Fuel sorption (1)
- Full-Notch Creep Test (FNCT) (1)
- Functionalized graphene (1)
- GHS (1)
- GMA welding (1)
- GTN model (1)
- Gas flow assisted powder deposition (1)
- Gas metal arc welding (1)
- Gas sorption (1)
- Gastrointestinal barrier (1)
- Gasturbinen (1)
- Gated hybrid material (1)
- Gebindekonservierung (1)
- Gefahrgut (1)
- Gefahrstoff (1)
- Gekrümmte Oberflächen (1)
- General Aviation (1)
- Geothermie (1)
- Geringe Partikelfrachten (1)
- Geteilte Infrastruktur (1)
- Giant magnetoresistance (1)
- Git (1)
- Gitterkonstanten (1)
- Glas (1)
- Glass ceramic (1)
- Glue (1)
- Gnomonic projections (1)
- Gothic incursions (1)
- Gradient elution (1)
- Grain Boundary Segregation (1)
- Grain Boundary Spinodal (1)
- Grain boundary (1)
- Granules (1)
- Graphen Oxide (1)
- Graphitization (1)
- Gravimetry (1)
- Grooving (1)
- Gypsum' SAXS (1)
- HF (1)
- HNBR (1)
- Hastelloy X (1)
- Hazardous materials (1)
- Hazardous substances (1)
- Heat Treatment (1)
- Heat input (1)
- Heat transfer (1)
- Heat treatment (1)
- Heat-affected zone (1)
- Heizöl-20% Biodiesel-Blend (1)
- Heißrisse (1)
- Hematite (1)
- Heterodyning (1)
- Hexachlorodisilane (1)
- Hierarchical structures (1)
- High - temperature (1)
- High Strength Concrete (1)
- High density polyethylene (1)
- High pressure (1)
- High strength steels (1)
- High temperature oxidation (1)
- High-Entropy Alloys (1)
- High-density polyethylene (PE-HD) (1)
- High-entropy alloys (1)
- High-pressure high-temperature (1)
- High-strength low-alloy steel (1)
- High-temperature corrosion (1)
- High-temperature properties (1)
- Historical Developments (1)
- History (1)
- Hold time (1)
- Holzschutzmittel (1)
- Holzwerkstoffe (1)
- Homogeneous deposition (1)
- Hot crack (1)
- Hot isostatic pressing (1)
- Hot pressing (1)
- Hot stage microscopy (1)
- Hot tensile test (1)
- Hot working tool steel (1)
- Hybrid Manufacturing (1)
- Hybrid composite pressure vessel (1)
- Hybrid laser arc welding (1)
- Hybrid manufacturing (1)
- Hybridschweißen (1)
- Hydration (1)
- Hydrofluorination (1)
- Hydrogen diffusion (1)
- Hydrogen embrittlement (1)
- Hydrogen evolution reaction (1)
- Hydrous glass (1)
- Hygrometrie (1)
- I-TRIBOMAT (1)
- IC50 (1)
- IN718 (1)
- INCONEL 718 (1)
- IR (1)
- ISO (1)
- ISO/TC 229 (1)
- Identification (1)
- Imaging surface chemical analysis (1)
- Imaging techniques (1)
- Immunoassay (1)
- Immunoassays (1)
- Implant-Test (1)
- Implants (1)
- Impurities (1)
- In situ (1)
- In situ PXRD (1)
- In situ alloying (1)
- In situ measurement (1)
- In situ monitoring (1)
- In vivo imaging (1)
- In-situ Computed Tomography (1)
- In-situ ED-XRD (1)
- In-situ neutron diffraction (1)
- In-situ test (1)
- Inconel 686 (1)
- Inconel 718 (1)
- Incorrect classification (1)
- Indentation fracture toughness (1)
- Inelastic background (1)
- Inertisierung (1)
- Infrared spectroscopy (1)
- Ink (1)
- Insecticide (1)
- Instrument calibration (1)
- Instumented indentation test (1)
- Integrated analysis (1)
- Intelligent tribological material characterization (1)
- Intelligente tribologische Werkstoffcharakterisierung (1)
- Inter layer time (1)
- Interfacial strength (1)
- Interlaboratory comparision (1)
- Intermetallics (1)
- Internal friction (1)
- Intrinsic OER activity (1)
- Introduction (1)
- Ionic Liquids (1)
- Ionic liquid (1)
- Iridium compounds (1)
- Iron nanoparticles (1)
- Iron oxide (1)
- Iron reducing bacteria (1)
- Isothiazolinone (1)
- Joining technology (1)
- Kaltrisssicherheit (1)
- Kaltzähe Stähle (1)
- Keramik (1)
- Keyhole mode welding (1)
- Kikuchi diffraction (1)
- Kikuchi patterns (1)
- Kinetic study (1)
- Klebung (1)
- Kleine Partikel (1)
- Klimawechseltest (1)
- Klon A1.1.1 (1)
- Klon EW75C (1)
- Kokillenguss (1)
- Komposit (1)
- Korrosionsmonitoring (1)
- Korrosionssensoren (1)
- Kreuzreaktion (1)
- Künstliche Intelligenz (1)
- L-PBF IN718 material (1)
- LIBS (1)
- LIBS TIG welding (1)
- LLG (1)
- LTT (1)
- LTT filler metal (1)
- Lab-to-field up-scaling (1)
- Lab-to-field upscaling (1)
- Laboratory XµCT (1)
- Lack-of-fusion (1)
- Laminography (1)
- Lamé curves approximation (1)
- Landau Lifshitz equation (1)
- Lanthanides (1)
- Lanthanoide (1)
- Large-scale tests (1)
- Laser Metal Deposition (1)
- Laser Metal Deposition; Laser Beam Welding; Duplex; Stainless Steel (1)
- Laser Powder Bed Fusion (L-PBF) (1)
- Laser ablation (1)
- Laser beam melting (LBM) (1)
- Laser cladding (1)
- Laser hybrid welding (1)
- Laser powderbed fusion (1)
- Laser-Hybridschweißen (1)
- Laser-Pulver-Auftragschweißen; Laserstrahlschweißen, Duplex, Pufferschichten (1)
- Laser-induced micro- and nanostructures (1)
- Laser-induced periodic surface structures, LIPSS (1)
- Laser-induced x-ray emission (1)
- Laserimplantation (1)
- Lateral flow assay (1)
- Lateral flow test (1)
- Lateral resolution (1)
- Lattice misfit (1)
- Lattice rotation (1)
- Lattice structures (1)
- Lattices (1)
- Layer-by-layer deposition (1)
- Layered manganese oxide (1)
- Layerwise Slurry Deposition (1)
- Lead (1)
- Lead books (1)
- Lead ions (1)
- Legierung (1)
- Lehm (1)
- LiYF4 (1)
- Lichtwellenleiter (1)
- Ligandsubstitution (1)
- Light harvesting (1)
- Limnoria spp (1)
- Linux (1)
- Liquid chromatography (1)
- Liquid metal embrittlement (1)
- Literature survey (1)
- Lithium-ion battery (1)
- Load-bearing (1)
- Lorentz force (1)
- Low cycle fatigue (1)
- Low expansion (1)
- Low feed rates (1)
- Low temperature (1)
- Low transformation temperature (1)
- Low-cement concrete (1)
- Low-cycle-fatigue behaviour (1)
- Low-loading (1)
- Lubricants (1)
- Luminescence (1)
- Lunar regolith (1)
- Luorescence (1)
- MCC (1)
- MGS-1 regolith simulant (1)
- MIC (1)
- MID IR Spectroscopy (1)
- MS (1)
- MVT (1)
- MWIR (1)
- Macroscopic stress (1)
- Magnesium (1)
- Magnesium Alloy (1)
- Magnetic moment (1)
- Magnetic nanoparticles (1)
- Magnetohydrodynamics (1)
- Manuscript making (1)
- Manuscripts (1)
- Marine borers (1)
- Mars (1)
- Material and damage behaviour (1)
- Material properties (1)
- Material-binding Peptides (1)
- Materialkennwerte (1)
- Materials (1)
- Materials Informatics (1)
- Materials behavior (1)
- Materials database (1)
- Materialschaedigung (1)
- Materialschädigung (1)
- Materialwissenschaft (1)
- Mathematical modeling (1)
- Matrix residual stress (1)
- Matter reorganization theories (1)
- Mauerwerk (1)
- Measurement methodology (1)
- Mechanical-technological properties (1)
- Mechanicalproperties (1)
- Mechanische Eigenschaften (1)
- Mechanochemical synthesis (1)
- Medical implants (1)
- Medium entropy alloys (1)
- Medium-entropy alloy (1)
- Melt pool defects (1)
- Melt pool depth (1)
- Melt pool monitoring (1)
- Melting (1)
- Merocyanine (1)
- Mesoporous iridium oxide films (1)
- Mesoporous particles (1)
- Messunsicherheit (1)
- Metadata structuring (1)
- Metal (1)
- Metal and alloys (1)
- Metal cluster (1)
- Metal fluorides (1)
- Metal matrix composites (1)
- Metal nanoparicels (1)
- Metal vapor (1)
- Metall (1)
- Metallene Werkstoffe (1)
- Metallic glass (1)
- Metals (1)
- Metastable phases (1)
- Metasurface (1)
- Methane (1)
- Methode (1)
- Methodology (1)
- Micro computed tomography (1)
- Microbeam analysis (1)
- Microbiological Corrosion (1)
- Microcracking (1)
- Microdosimetry (1)
- Microfocus X-ray computer tomography (μCT) (1)
- Micromagnetism (1)
- Micromechanics (1)
- Microplastic analysis (1)
- Microplastic mass contents (1)
- Microplastic particles (1)
- Microstrucrue Design (1)
- Microstructure Characterization (1)
- Mikro-Computertomographie (1)
- Mikroplasik (1)
- Mikroplastik-Analyse (1)
- Mikrostruktur (1)
- Mild steel (1)
- Minimally-invasive parapatellar approach (1)
- Mining tailing (1)
- Mitochondria (1)
- Mixed conductors (1)
- Mn-oxides (1)
- Mn3O4 (1)
- Mobile anodisation (1)
- Modell der konstanten Flammentemperaturen (1)
- Modellierung (1)
- Modelling studies (1)
- Moisture (1)
- Molecular VOx catalysts (1)
- Molten pool dynamics (1)
- Molybdenum carbide (1)
- Monitoring Konzept (1)
- Monte-Carlo simulation (1)
- Moriscos (1)
- Multi-phase (1)
- Multi-scale measurements (1)
- Multilayer ceramic technology (1)
- Multiple crack propagation (1)
- Multiport (1)
- Mussel-inspired adhesives (1)
- Mustererkennung (1)
- Müller-Matrix Ellipsometrie (MM-IE) (1)
- NAP-XPS (1)
- NDT (1)
- NEXAFS (1)
- NFDI (1)
- NIR-II Imaging (1)
- NMR probe Development (1)
- Nafion 117 (1)
- Nano particles (1)
- Nano-ceramic-additive-manufacturing photoresin (1)
- Nano-characterisation (1)
- Nano-object (1)
- Nano-powder (1)
- Nano-related data (1)
- Nano-risk assessment (1)
- NanoCAM (1)
- Nanobiointerfaces (1)
- Nanocubes (1)
- Nanomaterial properties (1)
- Nanoparticle size distribution (1)
- Nanoparticle synthesis (1)
- Nanopartikel (1)
- Nanoplatform (1)
- Nanoplattform (1)
- Nanosafety services (1)
- Nanosensor (1)
- Nb3Sn (1)
- Near-field spectroscopy (1)
- Near-surface X-ray diffraction (1)
- Neutron Scattering (1)
- Neutron radiography (1)
- Neutron tomography (1)
- Ni-based austenitic welding electrode (1)
- Ni-based superalloy (1)
- Nickel (1)
- Nickel nanoparticles (1)
- Nickelbasis-Superlegierungen (1)
- Niobium (1)
- Niobium carbide (1)
- Nitroaromaten (1)
- Nitromoschus (1)
- Nnano particle (1)
- Non-destructive ambient analysis (1)
- Non-serrated inhomogeneous flow (1)
- Nonconformities (1)
- Noncovalent interactions (1)
- Nuclear magnetic resonance (1)
- Nucleus (1)
- Numerical Simulation (1)
- Numerical investigation (1)
- Numerical modeling (1)
- OOMMF (1)
- Oberflächenanalytik (1)
- Oberflächenintegrität (1)
- Oberflächenstrukturierung (1)
- Oberflächentexturierung (1)
- Object oriented micromagnetic framework (1)
- Octachlortrisilane (1)
- Online Process Monitoring (1)
- Ontologien (1)
- OpenScience (1)
- Operating Procedure (1)
- Optical detection (1)
- Optical flow (1)
- Optical measurement technique (1)
- Optical probes (1)
- Optical tomography (1)
- Optische Emissionsspektroskopie (1)
- Optische Konstanten (1)
- Oral uptake (1)
- Ordered mesoporous carbon (1)
- Organophosphonate (1)
- Orientation precision (1)
- Oscillating ball-on-disc test (1)
- Osmium (1)
- Osteochondral stifle joint defect (1)
- Oxidation (1)
- Oxyfuel (1)
- PCE-Based superplasticizer (1)
- PDT (1)
- PQQ (1)
- PVDF-Based membrane (1)
- PWHT (1)
- Packaging (1)
- Packing density (1)
- Palaeography (1)
- Parchment (1)
- Partial penetration welding (1)
- Particle architecture (1)
- Particle number concentration (1)
- Particle scattering (1)
- Particle, imaging (1)
- Path planning (1)
- Pattern matching (1)
- Peem (1)
- Peptide Library (1)
- Permeability tensor (1)
- Permittivity reduction (1)
- Pesticide (1)
- Phase Diagram (1)
- Phase diagrams (1)
- Phase transformation (1)
- Phase transformations (1)
- Phasenidentifikation (1)
- Phenothrin (1)
- Phosphorous flame retardant (1)
- Photoelectrochemistry (1)
- Photonic crystal (1)
- Physicochemical characterization (1)
- Physik (1)
- Piezoresistive cantilever (1)
- Pipeline (1)
- Pipeline steel of grade X120 (1)
- Piston alloy (1)
- Plasma treatments (1)
- Plasmonic nanofocusing (1)
- Plastic deformation (1)
- Plasticity (1)
- Plastics (1)
- Platinum (1)
- Platinum group metals (1)
- Platinum-ruthenium colloid (1)
- Plattform Material Digital (1)
- Polyaniline (1)
- Polycarbonate (1)
- Polycarbonate-co-dimethylsiloxane copolymer (1)
- Polychlorosilanes (1)
- Polyethylene (1)
- Polyethylene glycol (1)
- Polyioinic liquid (1)
- Polymer Matrix Composites (1)
- Polymer analysis/characterization (1)
- Polymer membranen (1)
- Polymer nanocomposite (1)
- Polymer-binding Peptides (1)
- Polymerwerkstoff (1)
- Polymerwerkstoffe (1)
- Polynorbornenes (1)
- Polynorbornes (1)
- Polyolefins (1)
- Polypropylene (1)
- Polysaccharides (1)
- Polyurethane (1)
- Polyurethane acetate vinyl acrylate (1)
- Polyvinyl formaldehyde foam (1)
- Pool dimensions (1)
- Pore size (1)
- Pore size distribution (1)
- Pore space (1)
- Pore structure (1)
- Pores (1)
- Porosification (1)
- Porosität (1)
- Porous carbons (1)
- Position of carboxylate group (1)
- Potassium ions (1)
- Potentiodynamic Polarization (1)
- Powder diffraction (1)
- Ppreheating temperature (1)
- Pprestressed bolt connection (1)
- Precipitation (1)
- Precision Profile (1)
- Preheating (1)
- Presshärten (1)
- Pressure vessel (1)
- Primer (1)
- Probe (1)
- Projection center (1)
- Propolis (1)
- Prostheses (1)
- Protection (1)
- Protein (1)
- Prozessüberwachung (1)
- Präzisionsprofil (1)
- Prüfgeschwindigkeiten (1)
- Prüfmethode (1)
- Pseudo-dynamic testing (1)
- Pseudo-translationalsublattices (1)
- Pufferschichten (1)
- Pull-off test (1)
- Pulse electric current sintering (1)
- Pulsed magnetic field (1)
- Pulverbettverfahren (1)
- Pyrethroid (1)
- Pyrotechnics (1)
- QUASES (1)
- Qualitätsicherung (1)
- Quantitative spectroscopy (1)
- Quantum dot (1)
- Quartzite mining tailing (1)
- Quecksilberporosimetrie (1)
- ROPPOC (1)
- Radiation protection (1)
- Radiation therapy (1)
- Rare earth elements separations (1)
- Rayleigh Rückstreuung (1)
- Reaction Sintering (1)
- Reactor conditions (1)
- Recyclable (1)
- Recycled mineral admixture (1)
- Redox (1)
- Reduced graphene oxide (1)
- Reference Material (1)
- Reference data (1)
- Reference nanomaterials (1)
- Reference standards (1)
- Referenzdaten (1)
- Referenzmaterial (1)
- Reflection spectroscopy (1)
- Refraction (1)
- Refractory alloys (1)
- Refractory chemically complex alloy (1)
- Regelwerke (1)
- Rejuvenation (1)
- Relative humidity (1)
- Relaxation (1)
- Relaxation metallic glasses (1)
- Reliable characterization (1)
- Renewable copolymers (1)
- Repelling surface coatings (1)
- Research data management (1)
- Residual stress in AM (1)
- Residual stress state (1)
- Resins (1)
- Resistance (1)
- Resistance spot welding (1)
- Resonance frequency (1)
- Retained Austenite (1)
- Review (1)
- Rheometry (1)
- Rhodiumcomplexes (1)
- Rice husk ash (1)
- Ring-opening polymerization (1)
- Ringversuche (1)
- Rissbildung (1)
- Risswachstum (1)
- Roadmap (1)
- Rosin (1)
- Roughness (1)
- Rubber seal (1)
- Röntgen-Refraktion (1)
- Röntgenrefraktion (1)
- Röntgenstrahlung (1)
- S-N curve (1)
- SBA-16 (1)
- SEC (1)
- SEM/EDS (1)
- SIF evaluation (1)
- SIMS (1)
- SMAW (1)
- SS316L alloy (1)
- STEM-in-SEM (TSEM) (1)
- Safety (1)
- Saline brine (1)
- Sample peparation (1)
- Sandstein (1)
- Sandsteine (1)
- Saponite (1)
- Saxs (1)
- Scaffold (1)
- Scanning Kelvin Probe Force Microscopy (1)
- Schadensanalyse (1)
- Schadenskunde (1)
- Schadenstolerante Bauteilauslegung, (1)
- Schadnesanalyse (1)
- Schallemission (1)
- Schichtdicke (1)
- Schimmel (1)
- Schutzgasschweißen (1)
- SchwarzP cells (1)
- Schweißnaht (1)
- Schweißsimulation (1)
- Schweißtechnik (1)
- Schwingfestigkeit (1)
- Schwingstreifen (1)
- Scythica Vindobonensia, (1)
- Seal (1)
- Seam geometry (1)
- Secondary ion mass spectrometry (1)
- Selbstdiagnose (1)
- Selective Laser Melting (SLM) (1)
- Selective laser beam melting (1)
- Selective oxidation (1)
- Self-assembly (1)
- Self-degrading (1)
- Self-organization (1)
- Semiconductor (1)
- Semiconductor quantum dot (1)
- Sensitization (1)
- Sensor molecules (1)
- Separation (1)
- Shared infrastruture (1)
- Shark profile (1)
- Sheep animal model (1)
- Shell (1)
- Ship building (1)
- Short Crack Propagation (1)
- Short crack propagation (1)
- SiGe (1)
- SiO2 (1)
- Silane (1)
- Silica (1)
- Silicon (1)
- Simulations (1)
- Single crystal Ni-Base superalloys (1)
- Single particle spectroscopy (1)
- Single-pass welding (1)
- Sintering (1)
- Size and size distribution (1)
- Size distribution (1)
- Size measurement (1)
- Slag (1)
- Slow crack growth (1)
- Slow crack growth (SCG) (1)
- Slurry (1)
- Small Data (1)
- Small-angle scattering (1)
- Small-area XPS (1)
- Small-spot XPS (1)
- Smartphone readout device (1)
- Smectite (1)
- Smouldering (1)
- Soda-lime silicate glass (1)
- Solar cells (1)
- Solid state NMR (1)
- Solid-binding Peptides (1)
- Solidification (1)
- Solubility (1)
- Solute atoms (1)
- Spannungsrelaxationsrisse (1)
- Spectral induced polarization (1)
- Spectrometry (1)
- Spectroscopic ellipsometry (1)
- Spectroscopy (1)
- Split-vacancy defect complexes (1)
- Spray drying (1)
- SrF2 (1)
- Stable crack growth (1)
- Staircase method (1)
- Standard Operation Procedures (1)
- Standard operation procedures (1)
- Standardarbeitsanweisung (1)
- Standardisierung (1)
- Statistical analysis (1)
- Statistischen Untersuchung (1)
- Steady-state weld pool (1)
- Steel (1)
- Steel corrosion (1)
- Steel fibre reinforced concrete (FRC) (1)
- Steel slag (1)
- Steel-concrete interface (1)
- Stochastic Landau Lifshitz Gilbert equation (1)
- Stofftransport (1)
- Strahlenschutz (1)
- Streifenlichtprojektion (1)
- Streifenlichtprojektionssystem (1)
- Stress concentration tensor (1)
- Stress distribution (1)
- Stress intensity factor (1)
- Strontium titanate (1)
- Structural Analysis (1)
- Structural Health Monitoring (1)
- Structural color (1)
- Structural dynamics (1)
- Structural health monitoring (1)
- Strukturüberwachung (1)
- Stumpfklebungen (1)
- Substructuring (1)
- Sulfates (1)
- Sulfidation (1)
- Superior sorbent (1)
- Superlegierungen (1)
- Supermartensitic steel (1)
- Supplementary cementitious material (1)
- Surface Activation (1)
- Surface analysis (1)
- Surface charge (1)
- Surface chemisttry (1)
- Surface coating (1)
- Surface group analysis (1)
- Surface plasmon polaritons (1)
- Surface roughness (1)
- Surface superconductivity (1)
- Surface texturing (1)
- Surface-initated grafting (1)
- Synchrotron Radiation (1)
- Synchrotron micro-tomography (1)
- Synchrotron tomography (1)
- Systematische Schadensanalysen, Prozeduren (1)
- Systems architecture (1)
- TEKKEN test (1)
- TGA (1)
- TGA-FTIR (1)
- TGA-MS (1)
- TNT (1)
- TOPAS (1)
- TOPAS-nBio (1)
- TTS (1)
- Targeted nanoparticle (1)
- Tauchwägung (1)
- Teilsättigung (1)
- Temperature (1)
- Temperature scaling (1)
- Teredo sp (1)
- Termites (1)
- Terpolymer (1)
- Test Improvement (1)
- Test method (1)
- Test setup (1)
- Testing procedure (1)
- Tetraethyl orthosilicate (1)
- Textile binder (1)
- Thermal analysis (1)
- Thermal cycles (1)
- Thermal cycling (1)
- Thermal desorption analysis (1)
- Thermal desorption mass spectrometry (1)
- Thermischer Ausdehnungkoeffizient (1)
- Thermoanalytische Verfahren (1)
- Thermodynamik (1)
- Thermoelectric properties (1)
- Thermographie (1)
- Thermophysikalische Eigenschaften (1)
- Thermoplastic prepreg (1)
- Thermoset composition (1)
- Thetaevolve (1)
- Thick-walled steel (1)
- Thickness (1)
- Thioimidazolium (1)
- Thixotropy (1)
- Three-dimensional Bone tissue engineering (1)
- Threshold (1)
- Thumor therapy (1)
- Ti-Nb alloy (1)
- Ti6Al4V alloys (1)
- TiB2 (1)
- TiC (1)
- TiN (1)
- Tiatanium (1)
- Time over threshold (1)
- Time-of-flight secondary ion mass spectrometry (1)
- Titanaluminid (1)
- Titania nanoparticles (1)
- Titanium aluminides (1)
- Titanium carbide (1)
- Titanium dioxide (1)
- ToF-SIMS (1)
- Tools (1)
- Topas-nbio (1)
- Torsional in situ fatigue testing (1)
- Total transmittance reflectance (1)
- Toughness (1)
- Toxic gases (1)
- Traceability derivation (1)
- Tragfähigkeit (1)
- Transformer (1)
- Transmission electron microscopy (TEM) (1)
- Transport packages (1)
- Transport regulations (1)
- Trends (1)
- Triazine (1)
- Tribo-Analytik (1)
- Tribo-analytics (1)
- Tribo-tests (1)
- Tribological data (1)
- Trinitrotoluol (1)
- Triobology (1)
- Triplet-triplet annihilation (1)
- Tunnelbauwerke (1)
- Two-photon polymerization (1)
- Type-I pyrethroids (1)
- UN Test N.5 (1)
- UN Test O.2 (1)
- UV-irradiation (1)
- Ultraschallunterstütztes Fräsen (1)
- Ultrashort pulse laser processing (1)
- Ultrasonic testing (1)
- Ultrasound gel (1)
- Unidirectional composites (1)
- V-notch impact toughness (1)
- VRFB (1)
- Validation (1)
- Validierung (1)
- Vanadium speciation (1)
- Varestraint test (1)
- Verbundwerkstoff (1)
- Vergleichsuntersuchungen (1)
- Verifizierung (1)
- Vernetzung (1)
- Verpressanker (1)
- Verzug (1)
- Vickers indentation (1)
- Vienna manuscript (1)
- Vinyl monomer (1)
- Virtueller Materialdatenraum (1)
- Vitrimer (1)
- Volatile organic compounds (1)
- Volatiles from thermosets (1)
- Volume changes (1)
- Volume specific surface area (1)
- Vorgehensweise (1)
- W-Cl Instandsetzungsprinzip (1)
- WAAM (1)
- Waste management (1)
- Wastewater (1)
- Water (1)
- Water content (1)
- Water speciation (1)
- Water stability (1)
- Water treatment (1)
- Water-bearing (1)
- Weibern tuff (1)
- Weld end crater (1)
- Weld fatigue (1)
- Weld metal (1)
- Weld root (1)
- Welding processing influences (1)
- Welding residual stresses (1)
- Welding simulation (1)
- Werkstoffauswahl (1)
- Werkstoffdaten (1)
- Werkstoffdatenbank (1)
- Werkstoffe (1)
- Werkstoffkennwerte (1)
- Werkzeugmodifikation (1)
- Wet chemical etching (1)
- White light interferometry (1)
- Wilhelm Conrad Röntgen (1)
- Wirksamkeit (1)
- Wärmebehandlung (1)
- X-Ray (1)
- X-Ray Refraction (1)
- X-Ray refraction (1)
- X-ray CT (1)
- X-ray Diffraction (1)
- X-ray Fluorescence (1)
- X-ray absorption spectroscopy (1)
- X-ray computed tomography (1)
- X-ray computed tomography (CT) (1)
- X-ray generation (1)
- X-ray instrumentation (1)
- X-ray refraction radiography (1)
- X-ray synchrotron tomography (1)
- X-rays (1)
- XAS (1)
- XRD (1)
- XRM (1)
- Yield stress (1)
- Yttrium silicates (1)
- ZFP (1)
- ZIF-8 (1)
- Zentrifugentechnologie (1)
- Zinc ferrite (1)
- Zinc oxide (1)
- Zinc phosphate (1)
- Zinküberzüge (1)
- Zirconia-toughened alumina (1)
- Zwischenlagenzeit (1)
- Zyklische Belastung (1)
- Zyklische R-Kurve (1)
- calibration (1)
- composites (1)
- contact resonance (1)
- dispersion (1)
- dye (1)
- fluorescence standards (1)
- nPSize (1)
- organic dyes (1)
- pH (1)
- particle size determination (1)
- photoluminescence (1)
- sample preparation (1)
- standardization (1)
- stress relaxation (1)
- surface group analysis (1)
- synthesis (1)
- µ-CT (1)
- Überlappbereich (1)
- ГИДРОДИНАМИКА (1)
- КОНВЕКЦИЯ (1)
- ЛАЗЕРНАЯ СВАРКА (1)
- МЕТОД КОНЕЧНЫХ ЭЛЕМЕНТОВ (1)
- СВАРОЧНАЯ ВАННА (1)
- ТЕМПЕРАТУРНОЕ ПОЛЕ (1)
- ТЕПЛОПРОВОДНОСТЬ (1)
- ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ (1)
Organisationseinheit der BAM
- 6 Materialchemie (208)
- 9 Komponentensicherheit (133)
- 5 Werkstofftechnik (95)
- 8 Zerstörungsfreie Prüfung (90)
- 7 Bauwerkssicherheit (87)
- 9.3 Schweißtechnische Fertigungsverfahren (69)
- 6.1 Oberflächen- und Dünnschichtanalyse (66)
- 1 Analytische Chemie; Referenzmaterialien (52)
- 8.5 Röntgenbildgebung (51)
- 6.3 Strukturanalytik (50)
Paper des Monats
- ja (7)
Eingeladener Vortrag
- nein (169)
Highly unrelaxed structural states of metallic glasses have often advantageous mechanical properties. Since metallic glasses continuously relax with time (age) or inherently are well relaxed after processing, methods to uniformly rejuvenate the material are needed. One approach that has received attention is the so-called cryogenic-cycling method, during which a metallic glass is repeatedly immersed into liquid nitrogen. In some cases, cryogenic cycling is truly efficient in increasing the stored excess enthalpy of metallic glasses, but it does not seem to be universally applicable to all alloys and structural states. The origins for these differences remain unclear due to our limited understanding of the underlying structural evolution. In order to shed more light onto the fundamental structural processes of cryogenic cycling, we pursue in-situ x-ray photon correlation spectroscopy (XPCS) to trace the atomic-scale structural dynamics of a Zr-based metallic glass in two different structural states (ribbon and bulk metallic glass). This method allows calculating the relaxation times as a function of time throughout the thermal cycling. It is found that the investigated glasses exhibit heterogeneous structural dynamics at 300 K, which changes to monotonic aging at 78 K. Cryogenic cycling homogenizes the relaxation time distribution for both structural states. This effect is much more pronounced in the ribbon, which is the only structural state that rejuvenates upon cycling. We furthermore reveal how fast atomic-scale dynamics is correlated with long-time average structural relaxation times irrespective of the state, and that the ribbon exhibits unexpected additional fast atomic-scale relaxation in comparison to the plate material. Overall, a picture emerges that points towards heterogeneities in fictive temperature as a requirement for cryogenic energy storage.
The hydrogen permeation current increase was noticed for carbon steel in 0.5 mol/L NaCl solution under strong anodic potentials, which is contrary to the common understanding. Hydrogen permeation under cathodic potentials has been widely studied because of possible hydrogen embrittlement failures of high strength steels in seawater, but investigations of anodic polarization on hydrogen permeation are fairly rare, as the hydrogen evolution reaction shall be retarded. To corroborate the observed phenomenon, experiments were conducted using both as-received and vacuum-annealed sheet specimens. It was verified that the observed phenomena originated from the released hydrogen in traps by metal dissolution under anodic polarization.
The feasibility of microbial hydrogen consumption to mitigate the hydrogen embrittlement (HE) under different cathodic potentials was evaluated using the Devanathan-Stachurski electrochemical test and the hydrogen permeation efficiency h. The hydrogen permeation efficiency h in the presence of strain GA-1 was lower than that in sterile medium. The cathodic potential inhibited the adherence of strain GA-1 to AISI 4135 steel surface, thereby reducing the hydrogen consumption of strain GA-1. The adherent GA-1 cells were capable of consuming ‘cathodic hydrogen’ and reducing the proportions of absorbed hydrogen, indicating that it is theoretically possible to control HE by hydrogen-consuming microbes.
Polymers that help tailoring rheological properties during the casting process have become inevitable constituents for all kinds of high-performance concrete technologies. Due to lacking industries, these typically crude-oil based admixtures are not readily available in many parts of the world, which limits the implementation of more sustainable high-performance construction technologies in these regions. Alternative polymers, which often demand for less processing, can be derived from local plant-based resources. The paper provides experimental data of flow tests of cement pastes with polysaccharides from Triumfetta pendrata A. Rich, acacia gum and cassava without and in the presence of polycarboxylate ether superplasticizer. The flow tests are amended by observations of the zeta potentials and the hydrodynamic diameters in the presence of and without calcium ions in the dispersion medium. The results show that in the presence of and without calcium ions all polysaccharides provide negative zeta potentials, yet, they affect flowability and thixotropy in different ways. Cassava starch, acacia gum, and the gum of Triumfetta pendrata A. Rich qualified well for robustness improvement, strong stiffening, and additive manufacturing, respectively. The reason for the different effects can be found in their average sizes and size distribution. Due to the promising results, a flow chart for local value chains is derived on the example of yet unused cassava wastes, which can be converted in parallel.
Non-conventional densely packed concrete mixtures are proposed and evaluated in this paper using engineered recycled mineral admixtures and recycled aggregates obtained from steel slag, quartz mining tailings, and quartzite mining tailings. High fines content sand-concretes containing coarser- and finer-than-cement recycled powders were designed to obtain blends with broader particle-size ranges and improved packing density. As a result, compressive strength up to 99 MPa, cement intensity up to 2.33 kg/m³/MPa, and consumption of recycled material up to 95 vol% were obtained. Compressive strengths up to 66 MPa and cement intensity up to 2.34 kg/m³/MPa were also obtained with the addition of coarse aggregates to such sand-concrete mixtures, with consumption of recycled material up to 96.5%. The results launch new insights on the role of recycled admixtures and aggregates on the mixture design of cement-based composites regarding efficiency improvement and technological performance.
Design : and use of engineered recycled mineral admixtures obtained from industrial and mineral waste are promising strategies to increase the range of materials suitable for use in cement-based composites. In this work, Portland cement-blended pastes containing mineral admixtures designed for improving particle packing were evaluated in the presence of low- and high-charge polycarboxylate-based superplasticizers. The powders were obtained from basic oxygen furnace slag, iron ore tailings, quartz mining tailings, and quartzite mining tailings. The zeta-potentials of the particles were obtained via electrophoretic mobility. The flow properties were evaluated by rheological tests performed in a Couette type rheometer. The hydration kinetics was evaluated by isothermal calorimetry and an adapted method based on the Vicat needle test. The high-charge PCE and the finer mineral admixtures produced more stable blends. Coarser mineral admixtures led to increased flowability and delayed hydration compared to finer ones. Steel slag powders presented the most significant plasticizer effects, but also the largest setting delays and segregation tendency. Quartz-rich superfines reduced the setting delays caused by the superplasticizers. In summary, both superplasticizers were effective in improving flow properties, but the high-charge PCE was effective in preventing segregation in pastes containing mineral admixtures coarser and heavier than cement.
The prediction of the properties of the materials used in the operation of components is of enormous importance, in order to accelerate the development process of new components. To evaluate new materials in terms of their performance (in a component), the development of new innovative methods is necessary. These methods can also be summarized under the term lab-to-field or materials – upscaling, meaning materials being characterised in a laboratory and their properties being upscaled to the component performance by means of e.g. simulation. i-TRIBOMAT is a EU funded project (H2020, GA Nr. 814494) aiming at building an Open Innovation Test Bed for tribological material characterization and offering corresponding services from tribological characterization of new materials to simulation models for predicting the performance of industrial components. By bundling the infrastructure, know-how for characterization and building a digital platform, i-TRIBOMAT becomes the world’s largest open innovation test bed for tribological material characterization.
Der Einsatz von hochfesten Stählen im Karosseriebereich des Automobilbaus hat während der letzten Jahre stark zugenommen. Hierzu zählen Dual- und Komplexphasenstähle, welche durch Kombination unterschiedlicher Gefügebestandteile auch deren Vorteile kombinieren, sowie TRIP (TRansformation Induced Plasticity) und Mangan-Bor Stähle, welche sehr gute Umformeigenschaften mit hohen Festigkeiten durch Martensitbildung bei der Umformung kombinieren. TWIP (Twinning Induced Plasticity) Stähle erreichen ähnliche Effekte durch forcierte Zwillingsbildung.
Die Ursachen für den Einsatz dieser Stähle liegen in dem Potential dieser Materialien zur Gewichts- und Kostenreduzierung, bei gleichzeitiger Erhöhung der Fahrgastsicherheit. Auf Grund der prinzipiell gegebenen Schweißeignung dieser Stähle, werden die klassischen Fügeverfahren im Karosseriebau wie das kostengünstige und effektive Widerstandspunktschweißen, das Metall-Schutzgas (MSG)-Schweißen oder das Laserschweißen angewendet. Allerdings treten teilweise Herausforderungen, beispielsweise durch Gefügeveränderungen in den Fügestellen auf, die zu ungewollten Aufhärtungen oder Erweichungen führen.
In diesem Projekt wird ein Verfahren entwickelt, mit welchem die lokalen Werkstoffeigenschaften von im Automobilbau typischen Werkstoffen und deren Fügestellen bestimmt werden können. Relevante Kennwerte sind in erster Linie das SpannungsDehnungs-Verhalten der verschiedenen Zonen einer Schweißverbindung; relevante Zonen wiederum sind neben dem Grundwerkstoff die Wärmeeinflusszone und das Schweißgut. Zu diesem Zweck wird das Verfahren der instrumentierten Eindringprüfung für den Einsatz bei hochfesten Stählen weiterentwickelt. Zunächst werden hierzu Zugversuche an einfachen Grundwerkstoffgeometrien durchgeführt. Im Anschluss wird die optische Dehnungsfeldmessung an stark taillierten, geschweißten Zugversuchsproben durchgeführt.
Die Taillierung dient dem Zweck, die WEZ auch mittels WPS über den gesamten Querschnitt der Probe erzeugen zu können, bzw. im Versuch auch Dehnungen in den relevanten Bereichen herbeizuführen.
Das im Projekt angewendete Auswerteverfahren, welches auf nichtlinearen Regressionsmodellen in Form von künstlichen, neuronalen Netzwerken beruht, ermöglicht die Vorhersage des Festigkeitsverhaltens des Werkstoffes anhand der gemessenen Krafteindringwegdaten.
Two types of cements were selected as the reference cement in the priority program 2005 of the German Research Foundation (DFG SPP 2005). A thorough characterization of CEM I 42.5 R has been made in a recent publication. In this paper, the characterization data of the other reference cement CEM III/A 42.5 N are presented from the aspects of chemical and mineralogical compositions as well as physical and chemical properties. The characterization data of the slag, which is the second main constituent of this specific cement besides the clinker, are presented independently. For all data received, the mean values and the corresponding errors were calculated. The data shall be used for the ongoing research within the priority program. Also, researchers from outside this priority program can benefit from these data if the same materials are used.
Supplementary cementitious materials (SCM) can reduce the total amount of Portland cement clinker in concrete production. Rice husk ashes (RHA) can be converted from an agricultural by-product to a high-performance concrete constituent due to a high amount of reactive silica with pozzolanic properties if they are burnt under controlled conditions. The way and duration of combustion, the cooling process as well as the temperature have an effect on the silica form and thus, the chemical and physical performance of the RHA. Various studies on the best combustion technique have been published to investigate the ideal combustion techniques. Yet, the process mostly took place under laboratory conditions. Investigating the difference between the performance of RHA produced in a rural environment and laboratory conditions is useful for the assessment and future enhancement of RHA production, and its application both as building material, for example in rural areas where it is sourced in large quantities, and as additive for high performance concrete. Thus, the paper presents a comparison between RHA produced under rudimentary conditions in a self-made furnace in the rural Bagamoyo, Tanzania and under controlled laboratory conditions at the Technical University of Munich, Germany, with different combustion methods and temperatures. In a second step, RHA was ground to reach particle size distributions comparable to cement. In a third step, cement pastes were prepared with 10%, 20% and 40% of cement replacement, and compared to the performance of plain and fly ash blended cement pastes. The results show that controlled burning conditions around 650 °C lead to high reactivity of silica and, therefore, to good performance as SCM. However, also the RHA burnt under less controlled conditions in the field provided reasonably good properties, if the process took place with proper burning parameters and adequate grinding. The knowledge can be implemented in the field to improve the final RHA performance as SCM in concrete.
Die additive Verarbeitung hochfester Feinkornbaustähle mittels Wire Arc Additive Manufacturing (WAAM) ist ein komplexes, aber zugleich auch effizientes Verfahren, bei dem Werkstoff, Bauteilgeometrie und Schweißprozess gezielt aufeinander abgestimmt sein müssen. Ziel dieser Studie war es, einen Zusammenhang zwischen den Prozessparametern und der generierten Schichtgeometrie zu ermitteln. Dazu wurden definierte Referenzkörper mit einem robotergestützten Schweißsystem additiv gefertigt und hinsichtlich Schichthöhe, Wandstärke und Mikrostruktur analysiert. Fokus der Untersuchung waren sowohl konventionelle als auch für die WAAM-Fertigung speziell entwickelte hochfeste Schweißzusatzwerkstoffe. Die geometrischen Eigenschaften additiv gefertigter Bauteile lassen sich insbesondere durch die Faktoren Drahtvorschubgeschwindigkeit und Schweißgeschwindigkeit gezielt einstellen. Jedoch können diese Parameter nicht beliebig variiert werden, auch aufgrund der rheologischen Eigenschaften der Zusatzwerkstoffe. Zu hohe Streckenenergien führen zu lokalen Überhitzungen und Fehlstellen in der generierten Schicht. Undefinierte Fließ- und Erstarrungsvorgänge im überhitzten Bereich erschweren die maßhaltige Fertigung. Deshalb wird bei speziellen WAAM-Schweißdrähten das Fließverhalten gezielt modifiziert, sodass es über einen größeren Temperaturbereich hinweg konstant ist. Erst die Kenntnis über die komplexen Zusammenhänge zwischen den Prozessparametern und der Bauteilgeometrie ermöglicht die Erzeugung exakter Schichtmodelle für die additive Fertigung. Dies bildet die Grundlage für die Bearbeitung weiterer Fragestellungen auf dem Gebiet der additiven Fertigung mit hochfesten Zusatzwerkstoffen und insbesondere deren Anwendung in modernen hochfesten Bauteilen.
Die Kenntnis von Materialeigenschaften spielt bei der Entwicklung oder Optimierung von Betonen und Bauweisen für den Straßenbau sowie der Qualitätssicherung eine bedeutende Rolle. Gleichermaßen bilden physikalische Materialkennwerte die Grundlage für die rechnerische Dimensionierung und die Restsubstanzbewertung von Betonfahrbahndecken. Eine relevante Kenngröße bei der Untersuchung thermisch induzierter Spannungs- und Verformungszustände stellt der thermische Ausdehnungskoeffizient dar. Im Zuge der systematischen Weiterentwicklung der rechnerischen Dimensionierung, aber auch im Zusammenhang mit der gezielten Verbesserung der Gebrauchseigenschaften von Betonfahrbahndecken gilt es zu hinterfragen, ob lastunabhängige Formänderungseigenschaften der verwendeten Betone aktuell ausreichend Beachtung finden, ob allgemeine Literaturwerte für die heutigen Fahrbandeckenbetone stets Gültigkeit besitzen und ob deren Implementierung in numerische Modelle zu realitätsnahen Vorhersagen führt. Für eine empirische Herangehensweise ist die Verfügbarkeit adäquater Prüfverfahren von entscheidender Bedeutung. In Deutschland existiert aktuell jedoch kein standardisiertes oder genormtes Verfahren für die prüftechnische Bestimmung des thermischen Ausdehnungskoeffizienten von Beton. Daher wurden unter Beachtung straßenbauspezifischer Gesichtspunkte zwei Prüfansätze entwickelt, die in diesem Beitrag vorgestellt sowie hinsichtlich möglicher Messunsicherheiten und Messungenauigkeiten diskutiert werden. Außerdem werden ausgewählte Ergebnisse aus Analysen an Bestandsbetonen aus dem BAB-Netz dargestellt. Im Ergebnis sollen die Untersuchungen einen Beitrag zur Schaffung der prüftechnischen Voraussetzungen für eine abgesicherte Quantifzierung der thermischen Dehnung von Fahrbahndeckenbetonen leisten.
Sulfate is abundant in the environment and, as a result, sulfate-containing minerals constitute a large and important focus of research. These minerals play an important role in many geochemical and industrial processes, including the sulfur cycle, the construction industry (e.g., plaster of Paris), fault tectonics, acid mine drainage, and even rare biominerals. Important to note are the abundant amounts of sulfate (minerals) located on the surface of Mars, and in meteorites, extending the relevance of this mineral group beyond the realm of our planet. In geological systems, sulfate minerals such as barite are also important for indicating certain sedimentation environments. In this regard, sulfate deposits can be used to evaluate the redox state of ancient oceans during early Earth time periods.
Es wurde im Rahmen dieser Arbeit eine neue Methode der Biokonjugation entwickelt, die es ermöglicht humane Antikörper ortspezifisch mit IgG-bindenden Peptiden zu konjugieren. Als Basis fungierte ein Peptid, welches für den Einsatz gezielt modifiziert wurde. So sollte am C-Terminus ein Biotin eingefügt werden, dass für die spätere Detektion der Biokonjugation genutzt werden kann, während am N-Terminus ein Cross-Linker für die kovalente Bindung zum Antikörper eingefügt wurde. Das Biotin wurde mittels Biotin-Lysin eingebaut. Dies hat den Vorteil, dass die modifizierte Aminosäure direkt in der SPPS genutzt werden kann. Auch der Cross-Linker soll schon während der SPPS in das Peptid integriert werden. Als Cross Linker wurden die zwei heterobifunktionellen Succinimidyl(3-bromoacetamid)propionate und Succinimidyl(4-iodacetyl)aminobenzoat untersucht. Die Aktivierung des Peptides mit dem SBAP-Cross-Linker erfolgte am besten im pH-Bereich zwischen 7,0 und 9,0. Die Modifizierung des Peptides mit dem Iodid-Cross-Linker SIAB unter den gleichen Bedingungen zeigte allerdings keine zufriedenstellenden Ergebnisse. Da das erste Peptid allerdings in den Folgeexperimenten sehr gute Ergebnisse zeigte, musste kein weiterer Linker getestet werden. Zusätzlich zu der Cross-Linker-Wahl sollte der Abstand zwischen dem Cross-Linker und dem Grundgerüst des Peptides auf den Einfluss der Bindung untersucht werden. Dazu wurden drei Kontrollpeptide synthetisiert, die entweder um zwei Aminosäuren zwischen dem ursprünglichen N-Terminus des Peptides und dem SBAP-Linker verlängert wurden, keinen SBAP-Linker beinhalten oder die Verlängerung ohne SBAP-Linker besaßen. Die erfolgreiche Synthese aller vier Peptide wurde mittels MALDI-TOF-MS bestätigt.
In 2019 over 30 000 people were killed or injured by explosions caused by explosives like TNT, PETN, HMX and RDX. Therefore, highly sensitive assays for the detection of TNT are needed. In this study we compared two commercially available TNT antibodies: A1.1.1 and EW75C with a highly optimized indirect competitive ELISA based on a BSA-TNA conjugate. As a result, a precision profile for both antibodies was determined with a LOD of 170 pmol L-1 for the clone A1.1.1 and a LOD of 3,2 nmol L-1 for the clone EW75C. The measurements showed that the clone A1.1.1 is a highly sensitive antibody for the detection of TNT while the clone EW75C does show medium performance at most.
In the cross-reactivity characterization of both antibodies many substances, closely related to the structure of TNT were tested. Both antibodies showed strong cross reactivity with trinitroaniline and trinitrobenzene. For the clone A1.1.1, which is known to originate from immunization of mice with an TNP-glycine-KLH conjugate, this has to be expected. Interestingly the clone EW75C, which was not characterized yet, showed similar behavior. This suggests a TNA-conjugate as immunogen for the EW75C antibody as well. None of both antibodies showed cross-reactions to the high explosives PETN, HMX and RDX. Also, the cross-reactions of nitro musks with the antibodies were investigated. Despite their prohibition, nitro musks are still used in Asia especially and are particularly popular in India. The overall superior clone A1.1.1 showed a significant cross-reactivity to musk ambrette. For practical reasons the influence of musk ambrette on this assay when used in natural environment should be investigated.
In further experiments, the highly sensitive TNT antibody A1.1.1 was digested with papain to obtain monovalent Fab-fragments. Due to its high stability against the digestion, a custom protocol for the IgG1 subclass of mice, to which the clone A1.1.1 belongs, was developed, resulting in a quantitative digestion of the intact antibody to Fab fragments. The success of the digestion was determined with MALDI-TOF-MS and SDS-PAGE. It was shown that this protocol worked for many different antibodies of IgG1 subclass as well.
CHG is very different compared to other graphite degenerations or defects;
Filigree, multi-branched string-like, 3d interconnected structure;
Morphology and volumetric amount of CHG cannot be accessed by stereological interpretation of 2d section data;
Field-tested, technically established method to quantify CHG in components not available;
Fatigue: CHG causes substantial reduction in fatigue limit and significant increase in crack growth rate;
Therefore: Avoid or exclude CHG!
High-entropy alloys containing up to 6 platinum group metals can be prepared by thermal decomposition of single-source precursors non requiring high temperature. We prepare the first example of a single-phase hexagonal high-entropy alloy. Heat treat- ment up to 1500 K and compression up to 45 GPa do not result in phase changes, a record temperature and pres- sure stability for a single-phase high-entropy alloy. The alloys show pronounced electrocatalytic activity in methanol oxidation, which opens a route for the use of high-entropy alloys as materials for sustainable energy conversion.
The Scythica Vindobonensia, the new fragments on Gothic incursions into Roman provinces in the Balkans in the middle of the third century AD that were revealed some years ago in a Greek palimpsest at the Austrian National Library in Vienna (ÖNB), are commonly considered as one of the most important additions of the last decades to the corpus of texts from classical Antiquity. Tere is a high degree of confdence among scholars in supposing that the fragments come from the lost work Scythica written in Greek by the third-century historian P. Herennius Dexippus (Δέξιππος) of Athens. The new fragments have hence also been called Dexippus Vindobonensis. In his Scythica, Dexippus recorded wars of the Romans with the Goths (and other tribes) whom he called Scythians.
The work had been hitherto known only from excerpts and quotes by later authors. Eight pages of a Byzantine manuscript copy of the ancient text have survived hidden underneath the visible surface of the last four parchment folios of the Vienna manuscript Historicus graecus 73, f. 192r -195v4. The copy is written in a Greek calligraphic minuscule which has been estimated by palaeographers to be of the middle or the second half of the eleventh century. In the thirteenth century, the text (on each of the eight pages arranged in one column, with 30 lines per page) was washed of the parchment and the valuable material made from animal skin was re-used for Christian texts. The new writing largely covered the faded remnants of the original text. It thus became hidden from the human eye for more than seven hundred years. Its discovery by Jana Grusková, a classical philologist specialized in the transmission of Greek texts, resulted from a systematic review of all Greek palimpsests kept at the Austrian National Library in Vienna at the beginning of the twenty-first century and a detailed examination of the four folios in 2007-20097.
High and medium entropy alloys gained increasing academic and industrial interest as novel materials for engineering applications. This project is aiming to clarify and compare the general and local corrosion properties of high entropy alloy CrMnFeCoNi and medium entropy alloy CrCoNi in different aqueous environments. The focus lies on the local corrosion processes that result either from microstructural imperfections (inclusions, defects at grain boundaries etc.) in the base material or processing related changes in the microstructure and/or local composition.
The corrosion behavior of the alloys was monitored via potentiodynamic polarization experiments and the local corrosion characteristics were further investigated by means of scanning electrochemical microscopy (SECM). Their passivation behavior was analyzed in three different electrolyte systems (NaCl, H2SO4 and NaClO4; c = 0.1M). The characterization of the surface morphology and composition of the passive film was performed by means of atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-Ray spectroscopy (SEM/EDX) and X-Ray photoelectron spectroscopy (XPS), respectively.
Considering long term corrosion effects, electrochemical work was supported with immersion tests and the analysis of corrosion products by SEM/EDX and XPS depth-profiling. Our results indicate that the medium entropy alloy CrCoNi has a significantly higher corrosion resistance in comparison to the high entropy alloy CrMnFeCoNi. The presentation will summarize some of our results on the mechanistical aspects of the observed high corrosion resistance.
In der Automobilindustrie stellt das Presshärteverfahren eine Schlüsseltechnologie zur ressourceneffizienten Herstellung sicherheitsrelevanter Karosserie-komponenten dar. Während der Umformoperation treten jedoch hohe Reibungs- und Verschleißerscheinungen an den interagierenden Werkzeug- und Werkstückwirkflächen auf, die sowohl die Bauteilqualität als auch die Maschinenstandzeit nachhaltig beeinträchtigen. Um die bestehenden Verfahrensgrenzen zu erweitern, wird daher eine Modifikation der Presshärtewerkzeuge mittels Laserimplantation angestrebt. Hierbei werden in die Werkzeugoberfläche keramische Hartstoffpartikel anhand eines gepulsten Laserstrahles eingebettet, infolgedessen kuppelförmige sowie höchstfeste Strukturen im Mikrometerbereich entstehen. Die Auswahl geeigneter Hartstoffmaterialien stellt jedoch ein entscheidendes und bisweilen limitierendes Kriterium dar, um defektfreie sowie verschleißresistente Oberflächenmodifikationen zu generieren. In diesem Zusammenhang wurden im Rahmen dieser Arbeit unterschiedliche titanbasierte Hartstoffpartikel auf presshärtespezifische Werkzeugstähle laserimplantiert und anschließend mittels modifizierten Pin-on-Disk-Tests hinsichtlich ihres tribologischen Einsatzverhaltens untersucht. Um die Wirksamkeit des Laserimplantationsverfahrens zu evaluieren, wurden zudem Verschleißuntersuchungen an unmodifizierten Werkzeugoberflächen durchgeführt und mit den erzielten Ergebnissen der lokal dispergierten Topographien verglichen.
Within the scope of this work, a laser implantation process has been used, in order to improve the tribological performance of hot stamping tools. This surface engineering Technology enables the generation of dome-shaped, elevated and highly wear resistant microfeatures on tool surfaces in consequence of a localized dispersing of hard ceramic particles via pulsed laser radiation.
As a result, the topography and material properties of the tool and thus the tribological interactions at the blank-die interface are locally influenced. However, a suitable selection of hard ceramic particles is imperative for generating defect-free surface features with a high share of homogenously disturbed particles. For this purpose, different niobium (NbB2 and NbC) as well as titanium-based (TiB2 and TiC) materials were embedded on hot working tool specimens and subsequently analyzed with regard to their resulting shape and mechanical properties. Afterwards, modified pin-on-disk tests were carried out by using conventional and laser-implanted tool surfaces, in order to evaluate the wear and friction behavior of both tooling systems.
While there is a permanent improvement of concrete pavement mixtures and pavement construction types over the last decades, the state-of-the-art joint sealing materials and joint constructions seem to stagnate on an antiquated empirical level. This status has been reaffirmed in the latest European standard. The consequences in the motorway network due to unsatisfying capability and durabilty of joint sealing systems are unacceptable. In addition, inadequate traffic performance (noise emissions, roll-over comfort) and traffic safety losses in the joint area of concrete pavements are existing challenges. These deficits and weaknesses reflect a demand for joint sealing materials and constructions whose approval requirements take functional aspects into account. Furthermore a sufficient analysis of decisive loads and a practice-oriented method to evaluate the requirements towards performance and durability is still missed. In this contribution decisive loads to German highways are analyzed. The design of test specimen for representative functional testing of joint sealing systems is discussed. The focus is on the geometry of the test specimens and the used concrete mixture. Finally, a new approach for a function-orientated test concept that considers representative load functions is presented. The potential of this approach to validate the durability and capability of various joint sealing systems is also presented using an example.
A set of some unexpected and interesting microstructures has put the so-called complex concentrated alloys (CCAs) in the eye of the scientific community. The AlMo0.5NbTa0.5TiZr refractory (r)CCA, aimed at substituting Ni-base superalloys in gas turbine applications, belongs to this alloy family. After a two-stage heat treatment, this rCCA morphologically resembles the typical a two-phase microstructure of the latter. The objective of this work consists in determining the effect of the two stages of the heat treatment on the microstructure of the AlMo0.5NbTa0.5TiZr alloy to eventually improve it in terms of homogeneity and porosity.
Die Bemessung von tragendem Lehmmauerwerk erfolgt in Deutschland auf Basis der Lehmbau Regeln. Das dort verankerte Nachweisverfahren beruht auf einem globalen Sicherheitskonzept, welches aus zuverlässigkeitstheoretischer Sicht nicht mehr dem Stand der Technik entspricht. Auf Grund dessen wird das Bemessungskonzept für Lehmmauerwerk vom Deutschen Institut für Bautechnik (DIBt) voraussichtlich 2023 außer Kraft gesetzt. Ein statischer Nachweis von tragenden Lehmbauten wäre in Deutschland dann ausschließlich mit einer Zustimmung im Einzelfall (ZiE) oder vorhabenbezogener Bauartgenehmigung (vBg) möglich. Beides ist mit erheblichem Mehraufwand und höheren Kosten verbunden, was für den Lehmmauerwerksbau einen entscheidenden Nachteil im Vergleich zum konventionellen Mauerwerksbau darstellt. Um eine unkomplizierte Praxisanwendung von Lehmmauerwerk zu ermöglichen, werden innerhalb eines Forschungsvorhabens, welches von der Bundesanstalt für Materialforschung und -prüfung (BAM), dem Institut für Massivbau der Technischen Universität Darmstadt sowie dem Ingenieurbüro ZRS durchgeführt wird, auf Basis der Produktnormen für Lehmsteine und Lehmmauermörtel Grundlagen für ein aktualisiertes Bemessungskonzept entwickelt. Im Rahmen des Projekts wird ebenfalls untersucht, inwiefern die Bemessungsregeln nach den vereinfachten Berechnungsmethoden für unbewehrtes Mauerwerk gemäß DIN EN 1996-3 / NA auf den Lehmmauerwerksbau übertragbar sind. Falls eine Anwendung des normativen Nachweisverfahrens bei Lehmmauerwerk möglich ist, wäre zukünftig eine Aufnahme von Lehmsteinen und Lehmmauermörtel in den nationalen Anhang des Eurocode 6 denkbar, was eine bedeutsame Erweiterung des Anwendungsbereichs von Lehmmauerwerk zur Folge hätte.
Diverse wissenschaftliche Untersuchungen konnten zeigen, dass bemessungsrelevante Festigkeits- und Verformungseigenschaften von Lehmmauerwerksbaustoffen stark von der vorherrschenden Materialfeuchte abhängen, welche im hygroskopischen Wassergehaltsbereich im Wesentlichen von der relativen Luftfeuchte (RLF) bestimmt wird. Auch die Zwischenergebnisse des laufenden Forschungsvorhabens zur Entwicklung eines Bemessungskonzepts für Lehmmauerwerk ergaben eine deutlich erkennbare Abhängigkeit zwischen der Materialfeuchte und den relevanten Festigkeits- und Verformungseigenschaften. Eine detaillierte Kenntnis des feuchteabhängigen Materialverhaltens von Lehmsteinen, -mörtel und -mauerwerk ist zwingend erforderlich, um ein konsistentes und zuverlässiges Bemessungskonzept für Lehmmauerwerk zu entwickeln. Im Rahmen des laufenden Forschungsprojektes werden deshalb umfangreiche Versuche zum Drucktragverhalten von Lehmsteinen und -mörtel sowie Lehmmauerwerk nach Konditionierung bei unterschiedlichen RLF durchgeführt und analysiert. Weiterhin werden auf Basis der experimentellen Ergebnisse numerische Modelle kalibriert, welche die detaillierte Analyse der Biegedrucktragfähigkeit von Lehmmauerwerk ermöglichen.
In diesem Beitrag werden zunächst die bisherigen Zwischenergebnisse bezüglich der experimentell ermittelten feuchteabhängigen Materialkennwerte von Lehmsteinen, -mörtel und -mauerwerk dargelegt. Darauf aufbauend werden numerische Untersuchungen zur Bestimmung der Systemtragfähigkeit von Lehmmauerwerk unter Feuchteeinflusses durchgeführt und erläutert.
The fracture mechanics-based IBESS approach is applied to the determination of FAT classes of butt welds with crack Initiation along the weld toe. The aim is an investigation of the effect of the geometrical parameters toe radius, flank angle, reinforcement and secondary notches such as roughness or undercuts. The influence of these parameters is discussed both individually and in combination; however, excluding statistical distributions of them and the material data. The results, when compared with conventional FAT classes for butt welds, are encouraging with respect to a potential contribution of IBESS to the discussion of more advanced quality criteria for welds. To that purpose, demands for further research are proposed.
Für die Bestimmung der Restlebensdauer zyklisch beanspruchter Bauteile kommt dem Schwellenwert für Ermüdungsrissausbreitung ∆Kth und dem sich anschließenden Schwellenwertbereich der da/dN-∆K-Kurve große Bedeutung zu. Dem stehen Unsicherheiten bei der Bestimmung und Analyse gegenüber. Der Aufsatz befasst sich mit der Ermittlung des sogenannten intrinsischen Schwellenwerts, der als robuster Eingangsparameter für eine „rissschließfreie“ Analyse der Restlebensdauer von entscheidender Bedeutung ist.
Monodisperse iron oxide nanoparticles as reference material candidate for particle size measurements
(2020)
In order to utilize and rationally design materials at the nanoscale the reliable characterization of their physico-chemical properties is highly important, especially with respect to the assessment of their environmental or biological impact. Furthermore, the European Commission’s REACH Regulations require the registration of nanomaterials traded in quantities of at least 1 ton. Powders or dispersions where 50% (number distribution) of the constituent particles have sizes ≤ 100 nm in at least one dimension are defined as nanomaterials. This creates a need for industrial manufacturers and research or analytical service facilities to reliably characterize potential nanomaterials. Currently, BAM is developing reference nanoparticles, which shall expand the scarce list of worldwide available nano reference materials certified for particle size distribution and will also target other key parameters like shape, structure, porosity or functional properties. In this respect, materials like iron oxide or titanium dioxide are considered as candidates to complement the already available silica, Au, Ag, and polystyrene reference nanoparticles.
The thermal decomposition of iron oleate precursors in high boiling organic solvents can provide large quantities of iron oxide nanoparticles that can be varied in size and shape.[1, 2] The presence of oleic acid or other hydrophobic ligands as capping agents ensures stable dispersion in nonpolar solvents. Such monodisperse, spherical particles were synthesized at BAM and pre-characterized by electron microscopy (TEM, SEM including the transmission mode STEM-in-SEM) and dynamic light scattering comparing cumulants analysis and frequency power spectrum.
1. REACH regulations and nanosafety concerns create a strong need for nano reference materials with diverse properties.
2. Iron oxide nanoparticles are under development as new candidate reference material at BAM.
3. Narrow particle size distribution confirmed by light scattering and electron microscopy.
A new approach towards performance-related design and scientific evaluation of joint sealing systems
(2020)
While there is a permanent improvement of concrete pavement mixtures and pavement construction types over the last decades, the state-of-the-art joint sealing materials and joint constructions seem to stagnate on an antiquated empirical level. This status has been reaffirmed in the latest European standard.
The consequences in the motorway network due to unsatisfying capability and durability of joint sealing systems are unacceptable. In addition, inadequate traffic performance (noise emissions, roll-over comfort) and traffic safety losses in the joint area of concrete pavements are existing challenges. These deficits and weaknesses reflect a demand for joint sealing materials and constructions whose approval requirements take functional aspects into account. Furthermore a sufficient analysis of decisive loads and a practice-oriented method to evaluate the requirements towards performance and durability is still missed.
In this contribution decisive loads to German highways are analyzed. The design of test specimen for representative functional testing of joint sealing systems is discussed. The focus is on the geometry of the test specimens and the used concrete mixture. Finally, a new approach for a function-orientated test concept that considers representative load functions is presented. The potential of this approach to validate the durability and capability of various joint sealing systems is also presented using an example.
As the most electronegative element, fluorine has a strong influence on material properties such as absorption behaviour or chemical and thermal stability. Fluorine can be easily integrated into coordination polymers (CPs) via a fluorinated acetate, here trifluoroacetate in Ba(CF3COO)2, or directly via a metal fluorine bond (BaF(CH3COO)). In the present study both possibilities of fluorine integration were tested and their effect on structure and properties of barium coordination polymers was investigated in comparison with the non-fluorinated barium acetate (Ba(CH3COO)2). In addition to the study of their thermal behaviour and their decomposition temperature, the CPs structures were tested for their application as possible anode materials in lithium ion batteries and for their sorption of water and ammonia. The properties of the CPs can be traced back to the individual structural motifs and could thus trigger new design ideas for CPs in LIBs and/or catalysis.
According to UN Test O.2, surprisingly, the polychlorosilanes hexachlorodisilane (HCDS), octachlorotrisilane (OCTS) and decachlorotetrasilane (DCTS) formally fulfill the criteria of the “test for oxidizing liquids”. This result is in contrast to the properties of polychlorosilanes that are described in the literature and those we have experienced in our own production.
By investigating the reaction products from the UN O.2 test reactor, using IR, Raman and XPS spectroscopy, it was shown that the results are not due to oxidizing properties of HCDS, OCTS or DCTS, but are caused by the specified test substance cellulose. To our knowledge, this is the very first substance class in which the reference substance oxidizes the test sample, instead of vice versa. This represents an important limitation of the internationally used UN Test O.2 for this substance class. The cause for this false-positive result is the known high degree of affinity of oxygen to silicon.
It is shown that the correctly executed UN Test O.2 produces false-positive results and that the polychlorosilanes do not have an oxidizing effect and, therefore, do not have to be classified as “oxidizing substances”.
Composition and microstructure stability of cement compound under cyclic hydrothermal condition
(2020)
There have been many researches focused on the performance improvement of ultra-high performance concrete (UHPC) by autoclaving treatment. The goal of autoclaving is to increase the pozzolanic reaction, and to densify the cement stone and the transition zone which originates from the incorporation of supplementary cementitious materials (SCMs), such as silica fume, fly ash and blast furnace slag. Due to the superior properties, UHPC can also be utilized under high mechanical load and aggressive condition, for example, the fabrication of water tanks for thermal storage which is of great significance for saving energy and reducing CO2 emission. It is known that mineral stability of the hydration products of an inorganic binder is highly related to the temperature and pressure of the environment. A certain stable composition at room temperature, however, may undergo a phase transformation at high temperature and the performance decrease under this severe condition will generally be more severe. In this way, the rationale behind this deterioration under long-term hydrothermal condition involving many cycles and long duration has to be clarified, and then appropriate optimizing methods will be performed in order to obtain a kind of construction with high durability under aggressive environment. For this purpose, different types and amounts of SCMs are introduced into the standard mixture of UHPC and the phase compositions after autoclaving at 200 °C and 15.5 bar are determined by combined X-ray diffraction and scanning electron microscope. Mercury intrusion porosimeter is used to characterise the microstructure of the samples. In order to establish the relationship between microstructure and macroscopic properties, compressive and flexural strength are also investigated.
Composition and microstructure stability of cement compound under cyclic hydrothermal condition
(2020)
There have been many researches focused on the performance improvement of ultra-high performance concrete (UHPC) by autoclaving treatment. The goal of autoclaving is to increase the pozzolanic reaction, and to densify the cement stone and the transition zone which originates from the incorporation of supplementary cementitious materials (SCMs), such as silica fume, fly ash and blast furnace slag. Due to the superior properties, UHPC can also be utilized under high mechanical load and aggressive condition, for example, the fabrication of water tanks for thermal storage which is of great significance for saving energy and reducing CO2 emission. It is known that mineral stability of the hydration products of an inorganic binder is highly related to the temperature and pressure of the environment. A certain stable composition at room temperature, however, may undergo a phase transformation at high temperature and the performance decrease under this severe condition will generally be more severe. In this way, the rationale behind this deterioration under long-term hydrothermal condition involving many cycles and long duration has to be clarified, and then appropriate optimizing methods will be performed in order to obtain a kind of construction with high durability under aggressive environment. For this purpose, different types and amounts of SCMs are introduced into the standard mixture of UHPC and the phase compositions after autoclaving at 200 °C and 15.5 bar are determined by combined X-ray diffraction and scanning electron microscope. Mercury intrusion porosimeter is used to characterise the microstructure of the samples. In order to establish the relationship between microstructure and macroscopic properties, compressive and flexural strength are also investigated.
Ultra high performance concrete (UHPC) is known for its high compressive strength of more than 150 MPa and its high durability. Thermal treatment at 90°C can accelerate the strength development so that the 28-days-strength can be achieved immediately after the treatment and an additional increase up to 30 % in some cases. The reason for the strength development is an accelerated hydration of the clinker minerals and an intensified pozzolanic reaction leading to a denser microstructure.
In previous research inhomogeneities in form of a zonation after unprotected thermal treatment were observed and analysed in respect to changes in the microstructure. This zonation is defined by a different microstructure in the core compared to the outer zone in the matter of porosity, mineral phase composition and a significant change in the potassium and sulphur concentration of the zones is measurable.
To isolate different transport mechanisms responsible for these element distributions UHPC samples were thermally treated at 90 °C and the microstructure was investigated under dry conditions and after immersion in water to investigate the influence of dehydration during and rehydration after the thermal treatment on the microstructure. Through durability testing via water absorption, water vapour diffusion, permeability testing and sulfuric acid resistance transport mechanisms like diffusion, migration, capillary suction are under investigation in correlation with the microstructure analysis. For the microstructure analysis measurements with µXRF, mercury intrusion porosity, XRD and SEM were conducted.
Ultra high performance concrete (UHPC) is known for its high compressive strength of more than 150 MPa and its high durability. Thermal treatment at 90°C can accelerate the strength development so that the 28-days-strength can be achieved immediately after the treatment and an additional increase up to 30 % in some cases. The reason for the strength development is an accelerated hydration of the clinker minerals and an intensified pozzolanic reaction leading to a denser microstructure.
In previous research inhomogeneities in form of a zonation after unprotected thermal treatment were observed and analysed in respect to changes in the microstructure. This zonation is defined by a different microstructure in the core compared to the outer zone in the matter of porosity, mineral phase composition and a significant change in the potassium and sulphur concentration of the zones is measurable.
To isolate different transport mechanisms responsible for these element distributions UHPC samples were thermally treated at 90 °C and the microstructure was investigated under dry conditions and after immersion in water to investigate the influence of dehydration during and rehydration after the thermal treatment on the microstructure. Through durability testing via water absorption, water vapour diffusion, permeability testing and sulfuric acid resistance transport mechanisms like diffusion, migration, capillary suction are under investigation in correlation with the microstructure analysis. For the microstructure analysis measurements with µXRF, mercury intrusion porosity, XRD and SEM were conducted.
Tetraethyl orthosilicate (TEOS) was used as a chemical precursor to deposit ultra-thin SiO x C y plasma polymer films onto mild steel surfaces for preventing the corrosion process. The structure–property relationships of the coatings were evaluated by X-ray Photo Spectroscopy (XPS), X-Ray Diffraction (XRD), Fourier Transform InfraRed spectroscopy (ATR-FTIR) and Energy Dispersive X-ray spectroscopy (EDX) completed with Scanning Electron Microscopy (SEM). The SEM micrographs confirmed a pinhole-free surface morphology of the low-pressure deposited plasma polymer films. The TEOS molecules become fragmented in the plasma by numerous collisions with energy-rich electrons and heavier particles. Recombination of fragments and condensation onto the steel substrate is responsible for the formation of organic SiO containing plasma polymer layers. Such thin layers consist of predominantly SiO x structures. Their properties are determined largely by the gap distance between the two samples used as electrodes in the plasma. The efficiency of the corrosion-protecting coating was compared with uncoated samples. The corrosion protection was determined by exposure of samples to 3.5% NaCl aqueous solutions. For this purpose, polarization and Electrochemical Impedance Spectroscopy (EIS) were used to monitor the corrosion. The optimal gap distance between the electrodes was determined for corrosion protection. The best protective efficiency reached more than 97% of the total protection as measured at room temperature.
The synthesis and optimization of superior and eco-friendly sorbents for Pb(II) pose a great challenge in the field of water treatment. The sorbent was developed by introducing graphene oxide (GO) into the matrix of polyvinyl formaldehyde (PVF) foam. The immobilization of GO in PVF results in significant increase in the maximum adsorption capacity (Qt) of GO powder for Pb(II), from ≈800 to ≈1730 mg g−1 in the case of GO/PVF foam. As compared with GO powder in Pb(II) aqueous solutions, PVF matrix keeps GO sheets stable without any agglomeration. The large surface area of GO sheet allows the abundant oxygenated functional groups on its surface to participate effectively in the Pb(II) adsorption process, leading to the huge increase of the Qt. Adsorption isotherms and kinetic studies indicated that the sorption process of Pb(II) on GO/PVF was done on heterogenous surface by ion-exchange reaction. The GO/PVF foam showed an excellent reusability for more than 10 cycles with almost the same efficiency and without any significant change in its physical properties.
Herein, two polyurethane oligomers were successfully synthesized using a prepolymer mixing process. The prepolymers were synthesized based on the step-growth addition polymerization of polypropylene glycol, Methylene diphenyl diisocyanate and 2-hydroxyethyl methacrylate or 2-hydroxyethyl acrylate. Isopropanol was functioned as the isocyanate blocking agent. Thereafter, different terpolymer emulsions were prepared by the emulsion graft copolymerization with the vinyl acetate monomer in presence of 2-ethylhexyl acrylate as a vinyl monomer. The chemical structures of the synthesized oligomeric monomers were probed by FTIR spectroscopy and found to vary with the content of acrylic monomer used in the oligomer synthesis phase (i.e.hydroxyethyl acrylate or hydroxyethyl methacrylate). The topography, thermal stability, and particle size of terpolymers were investigated by SEM, TGA, and zeta potential, respectively. The TGA results demonstrated marked enhancement in thermal stability of the synthesized terpolymers up to ca. 600°C, which was concurrent with enhanced surface homogeneity and film properties as evidenced by the SEM images. These terpolymers showed also property enhancement as binders for textile pigment printing in terms of rubbing resistance, color strength and fastness to washing when compared to the commercial binders.
These judgments would provide a new competent synthesis route by introducing polyurethane acetate vinyl acrylate as the binder for use in pigment printing of cotton fabrics.
We show how the combination of the spatial autocorrelation function and permeability calculations, applied to 3D X-ray computed tomography data, can yield quantitative information on the anisotropy of both meso-structure and fluid flow in Diesel Particulate Filter (DPF) materials, such as Cordierite and SiC. It was found that both the degree of anisotropy, and the orientation of the permeability and meso-structure are similar, but not identical. We confirm that the morphological anisotropy of cordierite materials is weak, and clearly influenced by the extrusion process that determines the main direction of anisotropy. Properties of the autocorrelation function are discussed and it is shown why estimating the characteristic length of real meso-structures (grain or ?pore? size) is not possible. Finally, we show that the autocorrelation function applied on grey-level images can give a good estimate of the degree of anisotropy even with limited resolution.
Elastomer seals are used in many industrial applications due to their excellent mechanical properties at a wide range of temperatures. Their high versatility and recovery potential under several load conditions make them well suitable for the application in containers designed for transport, storage and/or disposal of radioactive materials. In containers for low and intermediate level radioactive waste, elastomer seals are used as barrier seals, and as auxiliary seals in storage and transportation casks (dual purpose casks) for heat generating radioactive waste, such as spent fuel and high-level waste. While a seal exchange at defined intervals is typical in many conventional applications, it is impossible or at least hard to perform when principles of minimization of radiation exposure have to be considered and prohibit an unnecessary cask handling. An extensive knowledge of the change of the elastomer’s properties during aging and the availability of reliable end-of-lifetime criteria to guarantee the permanent safe enclosure of the radioactive material is mandatory. As BAM is involved in most of the national cask licensing procedures and in the evaluation of cask-related long-term safety issues, great efforts have been already made and are still planned to scientifically support this task.
Compression stress relaxation and compression set were identified as key indicators of elastomer long-term performance and quantitatively investigated in comprehensive test programs. Among other representative types of elastomers, specimens made from ethylene propylene diene rubber (EPDM) were tested before, during and after aging to capture the most important of their complex mechanical properties.
In the presented study, exemplary results were used to simulate the compression stress relaxation and the compression set of elastomer O-rings during aging. Regarding the influence of temperature, the time temperature superposition principle is applied in the relaxation analysis of elastomer O-rings. The proposed model is implemented in the commercial finite element software ABAQUS/Standard® [1] with a sequential temperature displacement coupling. Numerical results match the experimental compression stress relaxation measurements well. The prediction of compression set values after long-term aging shows a relatively good agreement with the experimental results. Nevertheless, all input parameters derived from the specimen tests, additional assumptions concerning boundary conditions and modeling strategy are discussed with regard to the identified slight discrepancies.
The possibility to extend the finite element model to represent the O-ring seal’s ability to recover after a (fast) partial release is taken into account
We demonstrate the potential of time-resolved luminescence spectroscopy for the straightforward assessment and in situ monitoring of the stability of upconversion nanocrystals (UCNPs). Therefore, we prepared hexagonal NaYF4:Yb3+,Er3+ UCNPs with various coatings with a focus on phosphonate ligands of different valency, using different ligand exchange procedures, and studied their dissolution behaviour in phosphate-buffered saline (PBS) dispersions at 20 °C and 37 °C with various analytical methods. The amount of the released UCNPs constituting fluoride ions was quantified by potentiometry using a Fluoride ion-sensitive electrode and particle disintegration was confirmed by transmission electron microscopy studies of the differently aged UCNPs. In parallel, the luminescence features of the UCNPs were measured with special emphasis on the lifetime of the sensitizer emission to demonstrate its suitability as Screening parameter for UCNP stability and changes in particle composition. The excellent correlation between the changes in luminescence lifetime and fluoride concentration highlights the potential of our luminescence lifetime method for UCNP stability screening and thereby indirect monitoring of the release of potentially hazardous fluoride ions during uptake and dissolution in biological systems. Additionally, the developed in situ optical method was used to distinguish the dissolution dynamics of differently sized and differently coated UCNPs.
Wood protection technology in the marine environment has changed over the last decades and will continue to do so. New active ingredients, newer formulations, and novel wood-based materials including physically- and chemically-modified wood, together with increasing concerns over environmental impacts of wood preservatives, urgently demand a major revision of EN 275 “Wood preservatives – Determination of the Protective Effectiveness against Marine Borers”, dated from 1992. This IRG document reports on the technical work in CEN TC 38 regarding the revision of this standard. A Task Group within WG 24 of CEN TC 38 was formed consisting of experts from different field of competence (e.g. wood preservatives industry, wood scientists, marine biologists, archaeologists and cultural heritage conservators). Starting by e-mail correspondence in 2014, and continuing with four physical meetings (Berlin 2x, Florence, Venice) with experts from Germany, Italy, Sweden, and UK were held so far. Significant items for revision in EN 275 were identified as: number of replicates, duration of the test, dimension of specimens, number of test sites, number of reference species, reference material including reference preservative, re-immersion of specimens after non-destructive periodical evaluation for longer periods of time vs higher number of replicates for successive destructive examinations without re-immersion, utilization of X- ray apparatus and specific software to ease evaluation, etc.
Furthermore, the task group is working on a standardized lab test for time-saving evaluation of different wood qualities for their potential to resist attack by limnorids. The suitability of this lab test will be determined by round robin tests as soon as safe face-to-face collaboration permits. The outcome will be published as a CEN TR (Technical Report) document, with a view to eventual adoption within the revised standard.
In diesem Beitrag werden am Beispiel von Gasturbinen Verfahren zur Charakterisierung des werkstoff-mechanischen Verhaltens sowie der Gefügeentwicklung von Bauteilen für Anwendungen bei hohen Temperaturen aufgezeigt. Gasturbinen sind technisch gesehen sehr interessante Systeme, die in der Energietechnik und in der Luftfahrt von hoher wirtschaftlicher Relevanz sind. Seit Jahrzehnten gelten Gasturbinen als klassische Innovationstreiber, für ihre Entwicklung wurden bereits maßgebliche Erneuerungen im Bereich der Aerodynamik und der Werkstofftechnik hervorgebracht.
Die Bereitstellung von zuverlässigen Werkstoffdaten stand für die Werkstoffprüfung seit dem 19. Jahrhundert in zentraler Stelle. Mit der zunehmender Digitalisierung unserer Gesellschaft gewinnt das Datenmanagement insbesondere im Hinblick auf die Modellierungs- und Simulationsaktivitäten an Bedeutung.
In unserem Beitrag beschreiben wir die gegenwärtigen Aktivitäten in Deutschland – insbesondere die NFDI-MatWerk und die BMBF-Initiative MaterialDigital – sowie in Europa und Übersee. Abschließend heben wir die Auswirkungen auf die technische und akademische Aus- und Weiterbildung.
In this presentation we discuss the online monitoring of metallic AM parts produced by the Laser Powder Bed Fusion (LPBF) process by using optical, thermographic and electromagnetic methods. In a first approach we present the detection of defects generated during the process and discuss how to improve these methods for the optimization of design and production of metallic AM parts.
The mechanical behavior of fiber reinforced composites with polymer matrix is governed by several mechanisms operating at different length scales. In this contribution we describe first non-destructive techniques which are adequate for the characterization of the fiber-matrix interphase at a microscopic level. In a second step we describe on a mesoscopic level the influence of manufacturing related elements on the mechanical properties of rotor blades for wind turbines. We concentrate on thermography, laminography and ultrasound in connection with mechanical testing systems. Finally we present methods for monitoring rotor blades by using embedded optical fibers.
Polymer nanocomposites (PNCs) with inorganic nanofillers dispersed in a polymer matrix have been widely studied from the 1990s, since the pioneering work by Toyota Central Research. The possibility of producing advanced tailor-made, light weight and low-cost materials, inspired academic and commercial research towards numerous potential applications, facilitating PNCs to become a billion-dollar global industry. The introduction of nanoparticles (NPs) to a polymer matrix is expected to result in improved properties. The outstanding performance of PNCs is determined not only by the characteristics of the used components but also by their phase morphology, including the dispersion of NPs and interfacial properties. Understanding of structure-property relationships is particularly important for polymer nanocomposites with high industrial significance, such as epoxy-based materials reinforced with inorganic nanofillers. These PNCs have been successfully adopted by the marine, automotive and aerospace industries, although they are still rarely studied on a fundamental level. Therefore, this thesis aims for a detailed understanding of the structure, molecular mobility and vitrification kinetics first, of two epoxy-based materials with different network structures and second, of the corresponding nanocomposites with different alumina-based nanofillers. The first system considered (EP/T-LDH) was based on bisphenol A diglycidyl ether (DGEBA) cured with diethylenetriamine (DETA) and taurine-modified layered double hydroxide (T-LDH) NPs. The taurine molecule bears additional functionalities that could enhance the interactions between the matrix and the nanofiller, improving the interphase formation. The seconds system (EP/BNP) was based on DGEBA and methyl tetrahydrophtalic acid anhydride (MTHPA) as a hardener, reinforced with boehmite nanoparticles (BNPs). The comparison of the two systems enables for a comparative study on the effect of different hardeners and the morphology and modification of the alumina-based nanofillers on the material behavior. The materials were investigated employing complementary techniques with different sensitivities and frequency windows. The following methodology was used: transmission electron microscopy (TEM), small – and wide – angle X-ray scattering (SAXS/WAXS), broadband dielectric spectroscopy (BDS), calorimetry in a form of conventional DSC and fast scanning calorimetry (FSC), as well as specific heat spectroscopy (SHS) in a form of temperature modulated DSC, temperature modulated FSC and static FSC by calculating the thermal relaxation rates from the cooperativity approach. The FSC method (based on adiabatic chip calorimetry to probe micrometer-sized samples) was successfully employed in this work, exploiting all its possibilities for the first time in literature for a PNC. Moreover, a systematic analysis technique was established to overcome the problem of vague glass transition regions observed for highly loaded PNCs in the heat flow and heat capacity curves.
First, TEM, SAXS/WAXS and indirectly BDS and SHS were employed to obtain the information about the approximate morphology of the PNCs. It was found that epoxy-based materials exhibit a structural heterogeneity in a form of regions with different average crosslinking density. This was indicated by multiple-peak scattering pattern of the polymer matrix and two distinct α-processes (dynamic glass transition) related to the cooperative fluctuation of the epoxy network found by BDS and SHS. This was described for the first time for epoxy-based materials. The two α-relaxations were evidenced differently for the two systems, which is related to different network structures and dipole moments due to the employed hardeners. Nevertheless, structural heterogeneity is an intrinsic feature of these materials, independent of the type of hardener used for the network formation and nanofiller. In addition, matrix inhomogeneities were more pronounced with increasing nanoparticle content. Furthermore, a powerful new technique was applied for X-ray scattering data, using Monte Carlo fits, to describe the NPs dispersion throughout the whole sample volume (as opposed to the local investigations performed by most researches). Additional structural information of the two systems was extracted by BDS and SHS, such as qualitative and quantitative estimation of polymer segments physically adsorbed and/or chemically bonded onto the nanoparticles. Due to the immobilized character of this interphase with respect to the cooperative segmental motions, it is denoted as a rigid amorphous fraction (RAF). For instance, on the contrary to EP/BNP, for EP/T-LDH a dielectrically active process was found, related to the localized fluctuations within RAF. Moreover, the amount of RAF in EP/T-LDH was reaching up to 40 wt % of the system, whereas in EP/BNP it ranged between 1-7 wt %. In the latter case the presence of NPs was found to simultaneously increase and decrease the number of mobile segments, due to the interphase formation and changes in crosslinking density. The difference between the two systems was ascribed to the presence of additional amine functionalities in the T-LDH nanofiller.
Second, employing BDS and SHS, a systematic study on the effect of NPs on the segmental dynamics was performed. For example, depending on the nanofiller, the α-processes related to regions with higher crosslinking density was found to shift to higher and lower temperatures with increasing T-LDH and BNPs concentration, respectively. The observed difference is due to the different synergism of the polymer matrix with the nanofiller.
Third, a detailed investigation of the vitrification kinetics was performed with DSC and FSC. The concentration dependence of the glass transition temperature was found, similar to the behavior of the α-processes. It was shown that, in parallel to the detected main glass transition, epoxy-based materials can exhibit an additional low temperature vitrification mechanism. As expected from the two distinct α-processes, this behavior was however not discussed in prior studies for an unfilled network former. This finding was correlated to the structural heterogeneity evidenced by other techniques.
This thesis, dealing with an in-depth research on the epoxy-based materials that are already successfully employed in numerous applications underlines the necessity of more fundamental research in this field. It shines light on the complexity of these systems and contributes to defining how the structure-property relationships can be determined by combining multiple experimental techniques and analytical methodology.
Micromechanical response of multi-phase Al-alloy matrix composites under uniaxial compression
(2020)
Aluminum alloys are extensively used in the automotive industry. Particularly, squeeze casting production of Al-Si alloys is employed in the conception of metal matrix composites (MMC) for combustion engines. Such materials are of a high interest since they allow combining improved mechanical properties and reduced weight and hence improve efficiency. Being a multiphase material, most MMCs show complex micromechanical behavior under different load conditions. In this work we investigated the micromechanical behavior of two MMCs, both consisting of a near-eutectic cast AlSi12CuMgNi alloy, one reinforced with 15%vol. Al2O3 short fibers and the other with 7%vol. Al2O3 short fibers + 15%vol. SiC particles. Both MMCs have complex 3D microstructure consisting of four and five phases: Al-alloy matrix, eutectic Si, intermetallics, Al2O3 fibers and SiC particles.
The in-situ neutron diffraction compression experiments were carried out on the Stress-Spec beamline and disclosed the evolution of internal phase-specific stresses in both composites. In combination with the damage mechanism revealed by synchrotron X-ray computed tomography (SXCT) on plastically pre-strained samples, this allowed understanding the role of every composite’s phase in the stress partitioning mechanism. Finally, based on the Maxwell scheme, a micromechanical model was utilized. The model perfectly rationalizes the experimental data and predicts the evolution of principal stresses in each phase.
Bei der Auslegung von Druckbehältern kommen, auf Grund ihrer hohen spezifischen Festigkeit, vermehrt Faserverbundwerkstoffe zum Einsatz. Durch eine hohe Streuung von Material- und Produktionsparametern sowie unterschiedlichster Belastungsszenarien gestaltet sich jedoch Aussagen über die Lebensdauer sowie eine Festlegung sinnvoller Prüffristen als schwierig. Im Fokus der Untersuchungen steht ein Behälterdesign mit metallischem Liner und einem kohlenstofffaserverstärkten Kunststoffverbund, wobei die Lebensdauer maßgeblich durch den im Metall vorherrschenden Eigenspannungszustand bestimmt wird. Mit Hilfe einer alterungsbegleitenden Eigenspannungsanalyse werden Eigenspannungsveränderungen erfasst und in einem erarbeiteten Betriebsfestigkeitsmodell berücksichtigt. Durch eine Nachstellung verschiedener Belastungsszenarien kann gezeigt werden, dass durch die Berücksichtigung einer veränderlichen Eigenspannung die Anzahl ertragbarer Lastwechsel bis zum Versagen sowie damit verbundene Überlebenswahrscheinlichkeiten mit einer erhöhten Genauigkeit abgeschätzt werden können.
Motivated by the tensile strength loss of 9%Ni steel arc welded joints made using Ni-based austenitic filler metals, the feasibility of maintaining the tensile strength using matching ferritic filler metal has been demonstrated. In comparison with shielded metal arc welded joint made using Ni-based austenitic electrode ENiCrMo-6, higher tensile strength comparable to that of the base metal was obtained using matching ferritic electrode. Besides, sufficient impact toughness energies with much lower mismatch were obtained for weld metal and heat-affected zone.
Welded joint with a lower mechanical mismatching is of considerable importance for achieving acceptable combination of tensile strength and impact toughness. A better combination of These mechanical properties is ensured by applying a post weld heat treatment.
To assess the clinical course of a sheep stifle joint model for osteochondral (OC) defects, medial femoral condyles (MFC) were exposed without patella luxation using medial parapatellar skin (3–4 cm) and deep incisions (2–3 cm). Two defects (7 mm diameter; 10 mm depth; OC punch) were left empty or refilled with osteochondral autologous transplantation cylinders (OATS) and explanted after six weeks. Incision-to-suture time, anesthesia time, and postoperative wound or impairment scores were compared to those in sham-operated animals. Implant performance was assessed by X-ray, micro-computed tomography, histology, and immunohistology (collagens 1, 2; aggrecan). There were no surgery-related infections or patellar luxations. Operation, anesthesia, and time to complete stand were short (0.5, 1.4, and 1.5 h, respectively). The wound trauma score was low (0.4 of maximally 4; day 7). Empty-defect and OATS animals reached an impairment score of 0 significantly later than sham animals (7.4 and 4.0 days, respectively, versus 1.5 days). Empty defects showed incomplete healing and dedifferentiation/heterotopic differentiation; OATS-filled defects displayed advanced bone healing with remaining cartilage gaps and orthotopic expression of bone and cartilage markers. Minimally-invasive, medial parapatellar surgery of OC defects on the sheep MFC allows rapid and low-trauma recovery and appears well-suited for implant testing.
Ni-based superalloys are well established in various industrial applications, because of their excellentmechanical properties and corrosion resistance at high temperatures. Despite the high development stage anda common industrial use of these alloys, hot cracking remains a major challenge limiting the weldability ofthe materials. As commonly known, the hot cracking susceptibility during welding increases with the amountof precipitation phases. Hence, a large amount of highstrength Ni-Alloys is rated as non-weldable. A newapproach based on electron beam welding at low feed rates shows great potential for reducing the hotcracking tendency of precipitation-hardened alloys. However, geometry and properties of the weld seamdiffer significantly in comparison to the common process range for practical uses. The aim of this study is toinvestigate the influence of welding parameters on the seam geometry at low feed rates between 1 mm/s and10 mm/s. For this purpose, 25 bead on plate welds on a 12 mm thick sheet made of Inconel 718 are carriedout. First, the relevant parameters are identified by performing a screening. Then the effects discovered arefurther studied by using a central composite design. The results show a significant difference between theanalyzed weld seam geometry in comparison to the well-known appearance of electron beam welded seams.
Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, chemistry, and their potential to enable advanced materials. To effectively understand and regulate the physico-chemical properties and potential adverse effects of nanoparticles, validated measurement procedures for the various properties of nanoparticles need to be developed. While procedures for measuring nanoparticle size and size Distribution are already established, standardized methods for analysis of their surface chemistry are not yet in place, although the influence of the surface chemistry on nanoparticle properties is undisputed. In particular, storage and preparation of nanoparticles for surface analysis strongly influences the analytical results from various methods, and in order to obtain consistent results, sample preparation must be both optimized and standardized. In this contribution, we present, in detail, some standard procedures for preparing nanoparticles for surface analytics. In principle, nanoparticles can be deposited on a suitable substrate from suspension or as a powder. Silicon (Si) Wafers are commonly used as substrate, however, their cleaning is critical to the process. For sample preparation from suspension, we will discuss drop-casting and spin-coating, where not only the cleanliness of the substrate and purity of the suspension but also its concentration play important roles for the success of the preparation methodology.
For nanoparticles with sensitive ligand shells or coatings, deposition as powders is more suitable, although this method requires particular care in fixing the sample.
Calcium alkali metal (potassium and sodium) double and triple phosphates have been synthesized in different ways. Was for the first time used reaction sintering to produce ceramics based on calcium alkali metal mixed phosphates and investigated the densification behavior of mixed phosphate-based multiphase materials during sintering by this method. Was presented the microstructure of polished surfaces of sintered samples differing in phase composition and determined the density of ceramics prepared using reaction mixtures differing in composition. The effect of reaction sintering on the porosity of the ceramics has been assessed. Using stereolithographic printing and reaction sintering, was produced macroporous mixed Calcium phosphate-based ceramic implants. Their compressive strength has been determined to be 0.78 ± 0.21 MPa for two-phase samples and 1.02 ± 0.13 MPa for three-phase samples.
In order to shorten time to market of products and to support new developments, the European Community is funding a HORIZON 2020 project called i-TRIBOMAT. In the field of tribology, renowned institutions combine their testing and analytical capabilities to provide the respective services. The later will be offered in Europe via a Single-Entry Point (SEP). Due to this combination of services, a testbed is created consisting of more than 100 tribometers. Thus, a large variety of testers exists, either commercially available or in-house built. Each tester is optimised to simulate a specific tribological contact situation. Currently, there is no standard available for the design of such testers. Especially, the way forces (normal load, friction force) and distances (e.g. stroke, linear wear) are measured, recorded and pre-processed differs from type to type. These forces and distances are essential for the determination of wear/ wear rates and coefficients of friction (COF), the core results of tribo-tests. This matter is complicated by the fact that e.g. for reciprocating motion, there are at least four different ways to determine COF. Depending on the testing conditions, these ways can lead to considerably different results. Currently, it is not obligatory to specify the method used for determining the COF.
In order to make data comparable, there is a need for measures which ensure that each tribometer is delivering similar, at best the same results under the same test conditions, irrespective of its manufacturer, design, location, determination method and even operator. The way forward are improved Round-Robin tests. First results and other challenges faced by creating comparable tribological data will be considered in the present contribution.
Composite Facade Elements with Self-Cleaning Surface made of Ultra-High-Performance Concrete (UHPC)
(2020)
In the framework of the European project H-House various concrete façade elements were developed with the aim to ensure a long service life by combining a very durable material with self-cleaning properties. The façade elements presented are made of a shell of UHPC filled with blocks of aerated autoclaved concrete as insulating material. Self-cleaning properties were realized amongst others by imprinting a microstructure into the surface during casting. The paper focuses on selected technological aspects of the manufacturing process of prototypes which had to be performed in two concreting sections. Furthermore the challenges faced when upscaling the self-cleaning properties are addressed and the strategy to assess the self-cleaning properties by measuring the contact and the roll-off angel is presented. The results show that a successfull upscalaing process requires detailed planning and that the best results can often be achieved with a moderate work effort or material use.
Composite Facade Elements with Self-Cleaning Surface made of Ultra-High-Performance Concrete (UHPC)
(2020)
In the framework of the European project H-House various concrete façade elements were developed with the aim to ensure a long service life by combining a very durable material with self-cleaning properties. The façade elements presented are made of a shell of UHPC filled with blocks of aerated autoclaved concrete as insulating material. Self-cleaning properties were realized amongst others by imprinting a microstructure into the surface during casting. The paper focuses on selected technological aspects of the manufacturing process of prototypes which had to be performed in two concreting sections. Furthermore the challenges faced when upscaling the self-cleaning properties are addressed and the strategy to assess the self-cleaning properties by measuring the contact and the roll-off angel is presented. The results show that a successfull upscalaing process requires detailed planning and that the best results can often be achieved with a moderate work effort or material use.
Irradiation with ultra-short (femtosecond) laser beams enables the generation of sub-wavelength laser-induced periodic surface structures (LIPSS) over large areas with controlled spatial periodicity, orientation, and depths affecting only a material layer on the sub-micrometer scale. This study reports on how fs-laser irradiation of commercially available Nb foil samples affects their superconducting behavior. DC magnetization and AC susceptibility measurements at cryogenic temperatures and with magnetic fields of different amplitude and orientation are thus analyzed and reported. This study pays special attention to the surface superconducting layer that persists above the upper critical magnetic field strength Hc2, and disappears at a higher nucleation field strength Hc3. Characteristic changes were distinguished between the surface properties of the laser-irradiated samples, as compared to the corresponding reference samples (non-irradiated). Clear correlations have been observed between the surface nanostructures and the nucleation field Hc3, which depends on the relative orientation of the magnetic field and the surface patterns developed by the laser irradiation.
Comprehensive Characterization of APTES Surface Modifications of Hydrous Boehmite Nanoparticles
(2020)
Hydrous boehmite (γ-AlOOH) nanoparticles (BNP) show great potential as nanoscale filler for the fabrication of fiber reinforced nanocomposite materials. Notably, the particle−matrix interaction has been demonstrated to be decisive for improving the matrix-dominant mechanical properties in the past years. Tailoring the surface properties of the nanofiller enables to selectively design the interaction and thus to exploit the benefits of the nanocomposite in an optimal way. Here, an extensive study is presented on the binding of (3-aminopropyl)triethoxysilane (APTES), a common silane surface modifier, on BNP in correlation to different process parameters (concentration, time, temperature, and pH). Furthermore, a comprehensive characterization of the modified BNP was performed by using elemental analysis (EA), thermogravimetric analysis (TGA) coupled with mass spectrometry (TGA-MS), and Kaiser’s test (KT). The results show an increasing monolayer formation up to a complete surface coverage with rising APTES concentration, time, and temperature, resulting in a maximal grafting density of 1.3 molecules/nm². Unspecific multilayer formation was solely observed under acidic conditions. Comparison of TGA-MS results with data recorded from EA, TGA, and KT verified that TGA-MS is a convenient and highly suitable method to elucidate the ligand binding in detail.
Online quality control of security relevant parts manufactured by Laser Powder Bed Fusion (LPBF) remains to be a challenge due to the highly complex process conditions. Furthermore, the influence of characteristic scan strategy parameters is not sufficiently clarified yet due to the commonly used method of single-track investigations. In this contribution, this topic is addressed by observing large 316L volume sections using in-situ melt pool monitoring by thermography in high temporal and spatial resolution. In detail, the influence of the scan angle on the melt pool geometry is investigated on. Characteristic melt pool features are extracted from the image data and analyzed using statistical methods data for altering scan angles. The results show significant changes in the melt pool dimensions and temperature distribution over the scan angle rotation. A first explanation approach is presented that connects the observed changes to phenomena of beam attenuation by metal vapor plume.
Fatigue failure of a component can occur at service loads considerably lower than the yield strength of the material. Under fatigue loading condition, the material in the vicinity of the tip of a propagating crack repeatedly deforms plastically, leaving microscopic marks on the crack surface, commonly known as fatigue striations. Counting and measuring fatigue striations is a method in estimating the number of loading cycles a component went through until fracture. Some studies suggest a one-to-one relation between the number of fatigue striations and the number of load cycles, but this relation is still debatable, given that there are many factors influencing the formation of those striations. The main purpose of this work is to analyze the influence of microstructure and mechanical strength on the formation of fatigue striations in structural steels, in order to understand how these material properties are related to the fatigue crack behavior. For such, standard Charpy-V samples were subjected to hardness, fatigue and impact testing. Metallography was performed to characterize the microstructure, and a fractographic analysis by using optical and scanning electron microscopy was carried out to investigate the fracture surface. This study shows that steels with higher ductility have a closer one-to-one relation than those with a higher tensile strength. Above a certain level of tensile strength, fatigue striations do form rarely or completely disappear.
The catalytic potential of bismuth subsalicylate (BiSub), a commercial drug, for ring-opening polymerization (ROP) of L-lactide was explored by variation of co-catalyst and polymerization time. Various monofunctional phenols or carboxylic acids, aromatic ortho-hydroxy acids and diphenols were examined as potential co-catalysts. 2,2´-Dihydroxybiphenyl proved to be the most successful co-catalyst yielding weight average molecular weights (uncorrected Mw values up to 185 000) after optimization of reaction time and temperature. Prolonged heating (>1-2h) depending on catalyst concentration) caused thermal degradation. In polymerization experiments with various commercial Bi(III) salts a better alternative to BiSub was not found. By means of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry a couple of unusual and unexpected transesterification reactions were discovered. Finally, the effectiveness of several antioxidants and potential catalyst poisons was explored, and triphenylphosphine was found to be an effective catalyst poison.
Segregation to grain boundaries affects their cohesion, corrosion, and embrittlement and plays a critical role in heterogeneous nucleation. In order to quantitatively study segregation and low-dimensional phase separation at grain boundaries, here, we apply a density-based phase-field model. The current model describes the grain-boundary thermodynamic properties based on available bulk thermodynamic data, while the grain-boundary-density profile is obtained using atomistic simulations. To benchmark the performance of the model, Mn grain-boundary segregation in the Fe–Mn system is studied. 3D simulation results are compared against atom probe tomography measurements conducted for three alloy compositions. We show that a continuous increase in the alloy composition results in a discontinuous jump in the segregation isotherm. The jump corresponds to a spinodal Phase separation at grain boundary. For alloy compositions above the jump, we reveal an interfacial transient spinodal phase separation.
The transient spinodal phenomenon opens opportunities for knowledge-based microstructure design through the chemical manipulation of grain boundaries. The proposed density-based model provides a powerful tool to study thermodynamics and kinetics of segregation and phase changes at grain boundaries.
The relationship between residual stresses and microstructure associated with a laser powder bed fusion (LPBF) IN718 alloy has been investigated on specimens produced with three different scanning strategies (unidirectional Y-scan, 90° XY-scan, and 67° Rot-scan). Synchrotron X-ray energy-dispersive diffraction (EDXRD) combined with optical profilometry was used to study residual stress (RS) distribution and distortion upon removal of the specimens from the baseplate. The microstructural characterization of both the bulk and the nearsurface regions was conducted using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). On the top surfaces of the specimens, the highest RS values are observed in the Y-scan specimen and the lowest in the Rot-scan specimen, while the tendency is inversed on the side lateral surfaces. A considerable amount of RS remains in the specimens after their removal from the baseplate, especially in the Y- and Z-direction (short specimen Dimension and building direction (BD), respectively). The distortion measured on the top surface following baseplate thinning and subsequent removal is mainly attributed to the amount of RS released in the build direction. Importantly, it is observed that the additive manufacturing microstructures challenge the use of classic theoretical models for the calculation of diffraction elastic constants (DEC) required for diffraction-based RS analysis. It is found that when the Reuß model is used for the calculation of RS for different crystal planes, as opposed to the conventionally used Kröner model, the results exhibit lower scatter. This is discussed in context of experimental measurements of DEC available in the literature for conventional and additively manufactured Ni-base alloys.
Development and characterization of starch film and the incorporation of silver nanoparticles
(2020)
Starch is one of the biopolymers being used for bioplastic synthesis. For production, starch can be combined with different plasticizers, starches from different plant sources and even with nanomaterials to improve or to add film properties. The challenge of adding these, e.g. in the form of silver nanoparticles (AgNp) is to determine the concentration so as to avoid impairing the properties of the film, agglomeration or altering the visual characteristics of the film. In this study, a starch film synthesis route and the incorporation of silver nanoparticles has been proposed in order not to alter the properties of the film while maintaining the transparency and a clear colour of the starch film. The results showed that the proposed synthesis route is promising, efficient, reproducible, fast and the film has good mechanical properties.
A powerful tool to understand, demonstrate and explain the limits of the pulsed technique in terms of detectability and localizability of AM keyhole pores has been assessed by comparing the active thermographic approach (both experimental and FEM simulations) to Computed Tomography results;
✓ µCT results demonstrate that the intended defect geometry is not achieved; indeed a network of voids (microdefects consisting of small sharp-edged hollows with a complicated, almost fractal, inner surface) was found;
✓ both Exp-PT and FEM results explains clearly why no indication of defect related to the thermal contrasts could be found during the investigation of an uncoated surface. However, the application of further data evaluations focusing on the thermal behavior and emissivity evaluation (PPT post data processing) enable the detection of some defects;
✓ coating facilitates a closer inspection of inner defects, but inhomogeneities of the coating could impair the spatial resolution and lead to the emergence of hotspots (the FEM simulation reached its limit with this extreme geometry where a 25 µm thin disc is considered at a 1 cm thick specimen in millisecond time resolution);
✓ both Exp-PT and FEM results allow the conclusion that very short pulses of 200 ms or shorter should be sufficient to detect these defects below, but near the surface; besides a short duration of the thermal phenomenon it should be emphasized, about 0.04 s (high frame rate camera);
Die geringe Zugfestigkeit von zementgebundenen Materialien kann durch die Zugabe von Fasern maßgeblich verbessert werden. Ziel eines gemeinsamen Verbundprojekts mit einem Industriepartner war die Erhöhung der Leistungsfähigkeit von kurzen Polymer- und Carbonfasern durch eine Verbesserung des Verbundes zwischen Faseroberfläche und Zementsteinmatrix.
Von der IONYS AG wurde dazu eine spezielle Funktionalisierung entwickelt, die über eine Hydrophilisierung der Faseroberfläche eine chemische Anbindung an die Zementsteinmatrix gewährleistet. Aufgabe der BAM war es, die Effizienz der neuen Beschichtung bezüglich der Erhöhung der Nachrissbiegezugfestigkeit und der Reduzierung der Schwindrissbildung während der Erhärtungsphase zu quantifizieren. Die Ergebnisse zeigen, dass die Funktionalisierung die Neigung zur Schwindrissbildung für die Carbonfasern und in noch stärkerem Maße für die Polymerfasern reduziert.
Eine Erhöhung der Nachrissbiegezugfestigkeit konnte dagegen nur für die deutlich steiferen Carbonfasern nachgewiesen werden.
Composite UHPC facade elements with self-cleaning surface: Aspects of technological manufacturing
(2020)
In the framework of the European collaborative project H-House, which was finished in 2017, large façade elements were developed consisting of a box shaped external shell of ultra-high-performance concrete (UHPC) with a functionalized surface and an insulation of autoclaved aerated concrete (AAC). The exposed concrete of the elements was further refined by adding self-cleaning properties to the surface through imprinting a microstructure in combination with chemical agents directly in the casting process. The paper focuses on selected technological aspects of the manufacturing process of large-scale prototypes. Presented are results of the upscaling process of functionalized surfaces from small specimen up to large UHPC composite facade elements produced for the construction of a demonstrator.
Thermomagnetic materials are a new type of magnetic energy materials, which enable the conversion of low temperature waste heat to electricity by three routes: Thermomagnetic motors, generators and microsystems. Taking our recent work on thermomagnetic generators as a starting point, in this talk we analyse the material requirements for a more energy and economic efficient conversion. We will describe the influence of magnetisation change and heat capacity on thermodynamic efficiency, as well as the consequences of thermal conductivity on power density. Our analysis will allow selecting the best thermomagnetic materials in Ashby plots and illustrate the substantial different properties compared to magnetocaloric materials. Supported by DFG, project FA 453/14)
To date, there are only very few technologies available for the conversion of low temperature waste heat to electricity. More than a century ago, thermomagnetic generators were proposed, which are based on a change of magnetization with temperature, switching a magnetic flux, which according to Faraday’s law induces a voltage. In this talk, we first describe the principle of thermomagnetic generators. Then we focus on the impact of topology of the magnetic circuit within thermomagnetic generators. We demonstrate that the key operational parameters strongly depend on the genus, i.e. the number of holes within the magnetic circuit. A pretzel-like topology of the magnetic circuit with genus =3 improves the performance of thermomagnetic generators by orders of magnitude. We will show that this technique is on its way to becoming competitive with thermoelectrics for energy harvesting near room temperature.
Additively manufactured metallic materials have already started to find application in safety-relevant components. However, this has only happened for certain materials and specific applications and loading conditions, since there is still an extensive lack of knowledge as well as of historical data regarding their mechanical behaviour. This contribution aims to address this lack of understanding and historical data concerning the creep behaviour of the austenitic stainless steel 316L manufactured by Laser-Powder-Bed-Fusion (L-PBF) and the low-cycle-fatigue behaviour of the titanium alloy Ti-6Al-4V manufactured by Laser-Metal-Deposition (LMD). Furthermore, it aims to assess their mechanical behaviour against their conventional counterparts. With that in mind, specimens from conventional and additive materials are tested and their mechanical behaviour analysed based on characteristic curves. To understand the damage behaviours the materials are characterized by destructive and non-destructive techniques before and after failure.
At the end of the sixteenth century, a number of relics and artefacts were discovered in Granada, Spain. They included what became known as the Lead Books of the Sacromonte, twenty-one written artefacts made of circular lead leaves engraved in archaic Arabic characters. The authorship was attributed to some Arab disciples of St James the Greater considered to be the first evangelisers of the Iberian Peninsula. The texts, the materiality and the circumstances of the discoveries fuelled a debate surrounding their authenticity that lasted more than two centuries, a debate so fierce and controversial that not even papal condemnation in 1682 was able to stop it. Soon after the discoveries were made public, scholars highlighted the many contradictions and errors of a historical, linguistic and theological nature present in the texts, identifying members of the local Morisco community as possible forgers. This article focuses on how the scholarly community of the sixteenth and seventeenth centuries handled these findings and looks at the methods employed by the scholars to evaluate the authenticity of the artefacts. It will also look at how the particular interests of the various authorities involved influenced the acceptance or dismissal of relevant academic results.
Die geringe Zugfestigkeit von zementgebundenen Materialien kann durch die Zugabe von Fasern maßgeblich verbessert werden. Ziel eines gemeinsamen Verbundprojekts mit einem Industriepartner war die Erhöhung der Leistungsfähigkeit von kurzen Polymer- und Carbonfasern durch eine Verbesserung des Verbundes zwischen Faseroberfläche und Zementsteinmatrix.
Von der IONYS AG wurde dazu eine spezielle Funktionalisierung entwickelt, die über eine Hydrophilisierung der Faseroberfläche eine chemische Anbindung an die Zementsteinmatrix gewährleistet. Aufgabe der BAM war es, die Effizienz der neuen Beschichtung bezüglich der Erhöhung der Nachrissbiegezugfestigkeit und der Reduzierung der Schwindrissbildung während der Erhärtungsphase zu quantifizieren. Die Ergebnisse zeigen, dass die Funktionalisierung die Neigung zur Schwindrissbildung für die Carbonfasern und in noch stärkerem Maße für die Polymerfasern reduziert.
Eine Erhöhung der Nachrissbiegezugfestigkeit konnte dagegen nur für die deutlich steiferen Carbonfasern nachgewiesen werden.
Composite UHPC facade elements with self-cleaning surface: Aspects of technological manufacturing
(2020)
In the framework of the European collaborative project H-House, which was finished in 2017, large façade elements were developed consisting of a box shaped external shell of ultra-high-performance concrete (UHPC) with a functionalized surface and an insulation of autoclaved aerated concrete (AAC). The exposed concrete of the elements was further refined by adding self-cleaning properties to the surface through imprinting a microstructure in combination with chemical agents directly in the casting process. The paper focuses on selected technological aspects of the manufacturing process of large-scale prototypes. Presented are results of the upscaling process of functionalized surfaces from small specimen up to large UHPC composite facade elements produced for the construction of a demonstrator.
Laser powder bed fusion (LPBF) of Ni-based superalloys shows great potential for high temperature applications, for example, as a burner repair application for gas turbines where the thin-walled structure is important. It motivates this work to investigate the evolution of microstructure and the anisotropic mechanical behavior when plate-like specimens are built with a thickness from 4 mm down to 1 mm. By performing texture analysis using neutron diffraction, a clear transition in fiber texture from <011> to <001> is indicated when the specimen becomes thinner. The residual stress shows no thickness dependence, and at the subsurface the residual stress reaches the same level as the yield strength. Due to the rough as-built surface, a roughness compensation method for mechanical properties of thin-walled structures is outlined and demonstrated. Tensile tests from room temperature up to 700 ◦C have been carried out. Anisotropic mechanical behavior is found at all temperatures, which is strongly related to the anisotropic texture evolution. Stronger texture evolution and grain rotations are discovered when the tensile loading is applied along the building direction. The mechanical behavior has been compared to a wrought material, where the high dislocation density and the subgrain structure of the LPBF material result in a higher yield strength. Combining the statistical texture analysis by neutron diffraction with mechanical testing, EBSD grain orientation mapping and the investigation of dislocation structures using transmission electron microscopy, this work illustrates the significance of texture for the thin-wall effect and anisotropic mechanical behavior of LPBF materials.
The hexapeptide hIAPP22–27 (NFGAIL) is known as a crucial amyloid core sequence of the human islet amyloid polypeptide (hIAPP) whose aggregates can be used to better understand the wild‐type hIAPP′s toxicity to β‐cell death. In amyloid research, the role of hydrophobic and aromatic‐aromatic interactions as potential driving forces during the aggregation process is controversially discussed not only in case of NFGAIL, but also for amyloidogenic peptides in general. We have used halogenation of the aromatic residue as a strategy to modulate hydrophobic and aromatic‐aromatic interactions and prepared a library of NFGAIL variants containing fluorinated and iodinated phenylalanine analogues. We used thioflavin T staining, transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS) to study the impact of side‐chain halogenation on NFGAIL amyloid formation kinetics. Our data revealed a synergy between aggregation behavior and hydrophobicity of the phenylalanine residue. This study introduces systematic fluorination as a toolbox to further investigate the nature of the amyloid self‐assembly process.
This is the repository of all experimental raw data used in the Scientific Reports publication "Specific adsorption sites and conditions derived by thermal decomposition of activated carbons and adsorbed carbamazepine" by Daniel Dittmann, Paul Eisentraut, Caroline Goedecke, Yosri Wiesner, Martin Jekel, Aki Sebastian Ruhl, and Ulrike Braun.
It includes
- overview_measurements.xlsx and overview_measurements.ods containing a list of all TGA experiments (TGA, TGA-FTIR, TED-GC-MS, and ramp-kinetics)
- TED-GC-MS.zip containing gas chromatography-mass spectrometry experimtent files for the Chemstation and OpenChrom
- TGA.zip containing thermogravimetric analyses raw data on evolved gas analyses experiments (TGA-FTIR and TED-GC-MS)
- TGA_kinetics.zip containing thermogravimetric analyses raw data on decomposition kinetic experiments (ramp-kinetics)
- TGA-FTIR.zip containing Fourier-transform infrared spectroscopy series files for OMNIC
- XRF.zip containing x-ray flourescence data on elemental composition
Dataset and Jupyter worksheet interpreting the (results from) small- and wide-angle scattering data from a series of boehmite/epoxy nanocomposites. Accompanies the publication "Competition of nanoparticle-induced mobilization and immobilization effects on segmental dynamics of an epoxy-based nanocomposite", by Paulina Szymoniak, Brian R. Pauw, Xintong Qu, and Andreas Schönhals.
Datasets are in three-column ascii (processed and azimuthally averaged data) from a Xenocs NanoInXider SW instrument. Monte-Carlo analyses were performed using McSAS 1.3.1, other analyses are in the Python 3.7 worksheet. Graphics and result tables are output by the worksheet.
This dataset is a complete set of raw, processed and analyzed data, complete with Jupiter notebooks, associated with the manuscript mentioned in the title.
In the manuscript, we provide a "systems architecture"-like overview and detailed discussions of the methodological and instrumental components that, together, comprise the "MOUSE" project (Methodology Optimization for Ultrafine Structure Exploration). Through this project, we aim to provide a comprehensive methodology for obtaining the highest quality X-ray scattering information (at small and wide angles) from measurements on materials science samples.
Moderne Segelflugzeuge sind voll-verklebte tragende FKV-Strukturen. Über die Schwingfestigkeit der Faser-Kunststoff-Verbunde (FKV) und die Lebensdauerabschätzung dieser Werkstoffklasse auf Basis verschiedener Lastspektren wurden insbesondere von Christoph Kensche verschiedenen Arbeiten durchgeführt und auch auf dem Symposium für Segelflugzeugentwicklung vorgestellt. Hingegen ist die Betriebsfestigkeit von Struktur-Klebungen im Anwendungsbereich der CS22 vergleichsweise wenig untersucht worden.
Über die Jahre wurden in verschiedenen Projekten immer wieder Probleme in Struktur-Klebungen (u.a. Betriebsbelastungsversuche an Versuchs-Holmen) identifiziert, analysiert und spezielle Prüfverfahren weiter entwickelt (Projekt „Tragflügel neuer Technologie für die allgemeine Luftfahrt“, FK SIF765). Im Rahmen des LuFo-Vorhabens GeAviBoo (General Aviation Booster) wurde in zwei Arbeitspaketen das Thema erneut aufgegriffen und Betriebsbelastungsversuche an Klebproben durchgeführt. Im Rahmen des Vortrages werden die Erkenntnisse der letzten 10 Jahre aufbereitet und die neusten Ergebnisse vorgestellt.
Motivated by the tensile strength loss of 9%Ni steel arc welded joints made using Ni-based austenitic filler metals, the feasibility of maintaining the tensile strength using matching ferritic filler metal has been demonstrated. In comparison with shielded metal arc welded joint made using Ni-based austenitic electrode ENiCrMo-6, higher tensile strength comparable to that of the base metal was obtained using matching ferritic electrode. Besides, sufficient impact toughness energies with much lower mismatch were obtained for weld metal and heat-affected zone.
Welded joint with a lower mechanical mismatching is of considerable importance for achieving acceptable combination of tensile strength and impact toughness.Abetter combination of These mechanical properties is ensured by applying a post weld heat treatment.
Development and characterization of starch film and the incorporation of silver nanoparticles
(2020)
Starch is one of the biopolymers being used for bioplastic synthesis. For production, starch can be combined with different plasticizers, starches from different plant sources and even with nanomaterials to improve or to add film properties. The challenge of adding these, e.g. in the form of silver nanoparticles (AgNp) is to determine the concentration so as to avoid impairing the properties of the film, agglomeration or altering the visual characteristics of the film. In this study, a starch film synthesis route and the incorporation of silver nanoparticles has been proposed in order not to alter the properties of the film while maintaining the transparency and a clear colour of the starch film. The results showed that the proposed synthesis route is promising, efficient, reproducible, fast and the film has good mechanical properties.
Eine kritische Aufgabe im Rahmen der Etablierung von Prozess-Struktur-Eigenschafts-Performance-Beziehungen bei der additiven Fertigung (AM) von Metallen ist die Ermittlung von zuverlässigen und gut dokumentierten Kennwerten zum Materialverhalten sowie das Schaffen von Wissen über die Struktur-Eigenschafts-Korrelation. Schließlich ist dies die Grundlage für die Entwicklung gezielterer Prozessoptimierungen und zuverlässigerer Lebensdauer-Vorhersagen. In diesem Zusammenhang zielt dieser Beitrag darauf ab, Daten und Erkenntnisse über das Kriechverhalten des austenitischen Edelstahls 316L zu liefern, der mittels Laser-Powder-Bed-Fusion (L-PBF) hergestellt wird. Um dieses Ziel zu erreichen, wurden Proben aus konventionellem warmgewalztem sowie AM-Material gemäß den bestehenden Normen für konventionelles Material geprüft und vor und nach dem Versagen mikrostrukturell charakterisiert. Die Probekörper wurden aus einzelnen Blöcken des AM-Materials gefertigt. Die Blöcke wurden mit einer Standard-Scan- und Aufbaustrategie hergestellt und anschließend wärmebehandelt. Das Kriechverhalten wird anhand der Kriechlebensdauer und ausgewählter Kriechkurven und Kennwerte beschrieben und vergleichend bewertet. Der Einfluss von Defekten und Mikrostruktur auf das Materialverhalten wird anhand von zerstörenden und zerstörungsfreien Auswertungen an ausgewählten Proben analysiert. Der AM-Werkstoff zeigt kürzere Kriechlebensdauern, erreicht das sekundäre Kriechstadium deutlich schneller und bei geringerer Dehnung und weist eine geringere Kriechduktilität im Vergleich zu seinem konventionellen Gegenstück auf. Das Kriechschädigungsverhalten des AM-Werkstoffs ist eher mikrostruktur- als defektgesteuert und ist durch die Bildung intergranularer Kriechrisse gekennzeichnet. Als kritische Merkmale werden die Versetzungsdichte sowie die Versprödung der Korngrenzen identifiziert. Die Mikro-Computertomographie (µCT) erweist sich als Alternative zur Metallographie, um die Kriechschädigung zu analysieren.
Many PhD students are interested in applying machine learning, AI, data science, etc., and there are many good reasons for this. However, there is a disconnect between mainstream data science and materials science, for example, when it comes to the sheer size of the data. This talk will highlight some of the unique challenges in materials informatics and present some interesting approaches to overcome them. Although the field is large, this talk will focus on cases that have some practical relevance to PhD students at BAM.
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.
Creep and fracture behavior of conventionally and additively manufactured stainless steel 316L
(2020)
A critical task within the frame of establishing process-structure-property-performance relationships in additive manufacturing (AM) of metals is producing reliable and well-documented material behavior’s data and knowledge regarding the structure-property correlation, including the role of defects. After all, it represents the basis for developing more targeted process optimizations and more reliable predictions of performance in the future. Within this context, this contribution aims to close the actual gap of limited historical data and knowledge concerning the creep behavior of the widely used austenitic stainless steel 316L, manufactured by Laser-Powder-Bed-Fusion (L-PBF). To address this objective, specimens from conventional hot-rolled and AM material were tested under application-relevant conditions according to existing standards for conventional material, and microstructurally characterized before and after failure. The test specimens were machined from single blocks from the AM material. The blocks were manufactured using a standard scan and build-up strategy and were subsequently heat-treated. The creep behavior is described and comparatively assessed based on the creep lifetime and selected creep curves and characteristic values. The effect of defects and microstructure on the material’s behavior is analyzed based on destructive and non-destructive evaluations on selected specimens. The AM material shows shorter creep lives, reaches the secondary creep stage much faster and at a lower strain, and features lower creep ductility compared to its conventional counterpart. The creep damage behavior of the AM material is more microstructure than defect controlled and is characterized by the formation and accumulation of single intergranular damage along the whole volume. Critical features identified are the grain morphology and the grain-boundary as well as the dislocation’s density. Micro-computed tomography (µCT) proves to be an alternative to metallography to analyze the creep damage.
Influence of the scanning strategy on the residual stress state in IN718 additive manufactured parts
(2020)
Laser Powder Bed Fusion (L-PBF) is an additive manufacturing technique enabling the design of complex geometries that are unrivalled by conventional production technologies. Nevertheless, L-PBF process is known to induce a high amount of residual stresses (RS) due to the high temperature gradients present during powder melting by laser. High tensile residual stresses are to be found the edges whereas the bulk material shows balancing compressive RS. Literature shows that the RS is highly sensitive to the process parameters. In particular, this study presents the characterization of the RS state in two L-PBF parts produced with a rastering scan vector that undergoes 90° or 67° rotation between subsequent layers.
Tuning and controlling the solid-state photophysical properties of organic luminophore are very important to develop next-generation organic luminescent materials. With the aim of discovering new functional luminescent materials, new cocrystals of 9-anthracene carboxylic acid (ACA) were prepared with two different dipyridine coformers: 1,2-bis(4-pyridyl)ethylene and 1,2-bis(4-pyridyl)ethane. The cocrystals were successfully obtained by both mechanochemical approaches and conventional solvent crystallization. The newly obtained crystalline solids were characterized thoroughly using a combination of single crystal X-ray diffraction, powder X-ray diffraction, Fourier-transform infrared spectroscopy, differential thermal analysis, and thermogravimetric analysis. Structural analysis revealed that the cocrystals are isostructural, exhibiting two-fold interpenetrated hydrogen bonded networks. While the O–H···N hydrogen bonds adopts a primary role in the stabilization of the cocrystal phases, the C–H···O hydrogen bonding interactions appear to play a significant role in guiding the three-dimensional assembly. Both π···π and C–H···π interactions assist in stabilizing the interpenetrated structure. The photoluminescence properties of both the starting materials and cocrystals were examined in their solid states. All the cocrystals display tunable photophysical properties as compared to pure ACA. Density functional theory simulations suggest that the modified optical properties result from charge transfers between the ACA and coformer molecules in each case. This study demonstrates the potential of crystal engineering to design solid-state luminescence switching materials through cocrystallization.
Amorphous calcium carbonate (ACC) is an important precursor in the biomineralization of crystalline CaCO3. In nature, it serves as a storage material or as a permanent structural element, whose lifetime is regulated by an organic matrix. The relevance of ACC in materials science is primarily related to our understanding of CaCO3 crystallization pathways and CaCO3/(bio)polymer nanocomposites. ACC can be synthesized by liquid–liquid phase separation, and it is typically stabilized with macromolecules. We have prepared ACC by milling calcite in a planetary ball mill. Phosphate “impurities” were added in the form of monetite (CaHPO4) to substitute the carbonate anions, thereby stabilizing ACC by substitutional disorder. The phosphate anions do not simply replace the carbonate anions. They undergo shear-driven acid/base and condensation reactions, where stoichiometric (10%) phosphate contents are required for the amorphization to be complete. The phosphate anions generate a strained network that hinders ACC recrystallization kinetically. The amorphization reaction and the structure of BM-ACC were studied by quantitative Fourier transform infrared spectroscopy and solid state 31P, 13C, and 1H magic angle spinning nuclear magnetic resonance spectroscopy, which are highly sensitive to symmetry changes of the local environment. In the first—and fast—reaction step, the CO32– anions are protonated by the HPO42– groups. The formation of unprecedented hydrogen carbonate (HCO3–) and orthophosphate anions appears to be the driving force of the reaction, because the phosphate group has a higher Coulomb energy and the tetrahedral PO43– unit can fill space more efficiently. In a competing second—and slow—reaction step, pyrophosphate anions are formed in a condensation reaction. No pyrophosphates are formed at higher carbonate contents. High strain leads to such a large energy barrier that any reaction is suppressed. Our findings aid in the understanding of the mechanochemical amorphization of calcium carbonate and emphasize the effect of impurities for the stabilization of the amorphous phases in general. Our approach allowed the synthesis of new amorphous alkaline earth defect variants containing the unique HCO3– anion. Our approach outlines a general strategy to obtain new amorphous solids for a variety of carbonate/phosphate systems that offer promise as biomaterials for bone regeneration.
n this work, three new pharmaceutical hydrated salts of ciprofloxacin with selected derivatives of benzoic acid, namely 4-hydroxybenzoic acid, 4-aminobenzoic acid and gallic acid, were obtained and systematically investigated by several solid-state analytical techniques. In situ Raman spectroscopy was applied to elucidate the alternative pathways of the solid forms' formation under mechanochemical conditions. Crystal structure analysis and a CSD survey allowed us to establish a distinct supramolecular motif formed by infinite columnar stacks of ciprofloxacin dimers arranged in the “head-to-tail” manner. An alternative “head-to-head” packing arrangement was only observed in the crystal of the hydrated ciprofloxacin salt with 4-aminobenzoic acid. In addition, the pH-solubility behavior of the solid forms was thoroughly investigated. Furthermore, a distinct structure–property relationship between the specific features of the supramolecular organization of the hydrated salts and their solubility was observed and discussed.
The shape of the parts, created by the technology of laser metal deposition (LMD), is influenced by various parameters, for example, the power and diameter of the laser source spot. The contribution of energy from the laser affects the temperature distribution in the formed layers. The changing temperature in the working area entails a change in the geometry of the layers and affects the stability of the process. In this paper, experiments on the measurement of temperature cycles in the DLMD process with different directions of the filling track are carried out. An infrared camera was used to measure thermal cycles. The calibration of the acquired data (i.e. correspondence table between the intensity of thermal radiation of the material and the absolute temperature) was done with help of two-color pyrometer ex situ and in situ measurements. The experiments are carried out on two materials 316L and Inconel 718. The effect of the maximum temperature on the layer height is shown, and thermal cycles in the formation of layers for different filling strategies are presented.