Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
- 2019 (229) (entfernen)
Dokumenttyp
Sprache
- Englisch (202)
- Deutsch (26)
- Mehrsprachig (1)
Schlagworte
- Mechanochemistry (14)
- Nanoparticles (13)
- Boehmite (12)
- Surface functionalization (12)
- Laser-induced periodic surface structures (LIPSS) (10)
- Nanocomposites (10)
- SAXS (10)
- In situ (9)
- TED-GC-MS (9)
- Applications (7)
- Epoxy (6)
- Femtosecond laser (6)
- Femtosecond laser ablation (6)
- Microplastics (6)
- Atomic Force Microscopy (AFM) (5)
- Corrosion (5)
- Cyclization (5)
- Electron microscopy (5)
- MALDI-TOF MS (5)
- MIC (5)
- Nanoparticle (5)
- Polylactide (5)
- Rigid amorphous fraction (5)
- Broadband dielectric spectroscopy (4)
- Catalysis (4)
- Klebfestigkeit (4)
- Laser-induced X-ray emission (4)
- Laser-induced periodic surface structures, LIPSS (4)
- Mikroplastik (4)
- Nanocomposite (4)
- Polymers of intrinsic microporosity (4)
- Radiation protection (4)
- Reference materials (4)
- Simulation (4)
- Specific heat spectroscopy (4)
- Thin films (4)
- Traceability (4)
- Ultrashort laser material interaction (4)
- XRD (4)
- Absorption edge tomography (3)
- Additive manufacturing (3)
- Analytik (3)
- Analytische Zentrifuge (3)
- AuNP (3)
- Bending modulus (3)
- Carbon nanotubes (3)
- Catalyst (3)
- Cement (3)
- Corrosion monitoring (3)
- Crosslinking (3)
- Dielectric spectroscopy (3)
- Discotic Liquid Crystals (3)
- Dosimetry (3)
- EPMA (3)
- Flash DSC (3)
- Geant4 (3)
- Haftfestigkeit (3)
- Harmonisation (3)
- Inter-laboratory comparison (3)
- LLG (3)
- MCS (3)
- MOF (3)
- Microdosimetry (3)
- Micromagnetism (3)
- Monte-Carlo simulation (3)
- Mueller-Matrix imaging ellipsometry (3)
- Nanofibers (3)
- OOMMF (3)
- Particle size distribution (3)
- Polycarbonate (3)
- Polymer (3)
- Polymer blends (3)
- Polymers (3)
- Polyurethane (3)
- Rigidity (3)
- Small-angle scattering (3)
- Spectroscopic ellipsometry (3)
- Spectroskopic Imaging (3)
- Synthesis (3)
- X-ray scattering (3)
- XPS (3)
- AFM (2)
- ALD-Hybridprozesse (2)
- Acoustic levitation (2)
- Additive Manufacturing (2)
- Adhäsion (2)
- Adsorbed layer (2)
- Al2O3-Schichten (2)
- Atomic Layer Deposition (2)
- BAMline (2)
- BDS (2)
- Biofilm (2)
- Biofilmbildung (2)
- Brechungsindex (2)
- C3A (2)
- CAT-Technologie (2)
- Copolymer (2)
- Corrosion inhibition (2)
- DNA (2)
- DNA damage (2)
- Delayed addition (2)
- EOS (2)
- EU FP7 project NanoValid (2)
- Early hydration (2)
- Electron probe microanalysis (EPMA) (2)
- Ellipsometrie (2)
- Energy deposit (2)
- Exchange interaction (2)
- Ferromagnetism (2)
- Glass transition (2)
- Haftvermittler (2)
- High-pressure (2)
- Interphase (2)
- Iridium-titanium mixed oxides (2)
- Kleb- und Haftfestigkeit (2)
- LEE (2)
- Landau Lifshitz equation (2)
- Laserschutz (2)
- Localised corrosion (2)
- Magnesium alloy (2)
- Magnetic moment (2)
- Materialbearbeitung (2)
- Mehrprobenprüfung (2)
- Mesoporous thin films (2)
- Metal–organic frameworks (2)
- Microstructure (2)
- Mikroskaliert (2)
- Molecular masses (2)
- Monte Carlo (2)
- Müller-Matrix-Ellipsometrie (2)
- NEXAFS (2)
- NanoSIMS (2)
- Nanocharacterisation (2)
- Nanomaterialien (2)
- Nanomechanics (2)
- Nanoplastics (2)
- Nanoskaliert (2)
- Nanostructure (2)
- Normung (2)
- OH radicals (2)
- Oberflächenenergie (2)
- Oberflächengeometrie (2)
- Object oriented micromagnetic framework (2)
- Oxidation (2)
- Polycarboxylate ether (PCE) (2)
- Polyethylene (2)
- Polymer bilayer coatings (2)
- Polymer nanocomposites (2)
- Radiationtherapy (2)
- Radioactive decay (2)
- Resonance frequency (2)
- Röntgenemission (2)
- Sekundärstrahlung (2)
- Silica nanoparticles (2)
- Silicon (2)
- Small angle scattering (2)
- Small-angle X-ray scattering (2)
- Software (2)
- Standardisation (2)
- Stochastic Landau Lifshitz Gilbert equation (2)
- Structural anomalies (2)
- Structural inhomogenities (2)
- Surface modification (2)
- Synchrotron (2)
- Synchrotron tomography (2)
- TMDSC (2)
- Temeprature scaling (2)
- Thermal degradation (2)
- Thin polymer films (2)
- Thin polymeric films (2)
- UV degradation (2)
- Ultrakurze Laserpulse (2)
- VAMAS (2)
- VSSA (2)
- Verbundfestigkeit (2)
- X-ray and electron diffraction (2)
- X-ray diffraction (2)
- low energy electrons (2)
- particle scattering (2)
- 2,6-diaminopyridine (1)
- 3D coherence scanning interferometry (CSI) (1)
- 3d structuring (1)
- AEROSIL® OX50 (1)
- AET (1)
- AFM-IR (1)
- AISI 304L (1)
- Acrylamide (1)
- Additiv (1)
- Additives (1)
- Admixtures (1)
- Advanced Materials (1)
- Advanced materials (1)
- Ageing (1)
- Alite (1)
- Alkoxysilanes (1)
- Alpha (1)
- Analysis (1)
- Anatase (1)
- Antibacterial (1)
- Antifouling surface coatings (1)
- Antifriction coefficient (1)
- Antiviral activity (1)
- Artificial weathering (1)
- Atomic force microscopy (1)
- Atomic fraction (1)
- Automation (1)
- Bacterial adhesion (1)
- Ball milling (1)
- Beamline (1)
- Bestimmung der Messunsicherheit (1)
- Beta decay (1)
- Biofunctional Molecules (1)
- Bloch wall (1)
- Boehmite alumina (1)
- Boehmite nanoparticles (1)
- Brachytherapy (1)
- Broadband dielectric microscopy (1)
- Bulk material (1)
- Bulk temperature (1)
- Bundesoberbehörden (1)
- Böhmit (1)
- C-C coupling (1)
- C3S (1)
- COK-12 (1)
- Cancer (1)
- Cancer treatment (1)
- Carbon fibers (1)
- Catalysts (1)
- Catechol (1)
- Cationic photocuring (1)
- Cell size (1)
- Cement admixtures (1)
- Cement hydration (1)
- Centrifugal Adhesion Testing (1)
- Centrifugal Adhesion Testing (CAT) (1)
- Centrifugal Force (1)
- Certified reference materials (1)
- Certified standards (1)
- Cluster (1)
- Co (1)
- Co-crystal (1)
- Cobalt (1)
- Cobalt and zinc oxides (1)
- Cocrystal (1)
- Coherent exchange (1)
- Comparability of Measurement Results (1)
- Compressive Stress (1)
- Conference (1)
- Coupled corrosive and mechanial load (1)
- Coupled corrosive/mechanical load (1)
- Cristobalite frameworks (1)
- Crosslinking density (1)
- Curie temperature (1)
- Curing (1)
- Curved surfaces (1)
- Cyclic (1)
- Cycloaliphatic epoxy oligosiloxane (1)
- Cycloalyphatic epoxy oligosiloxane (1)
- DIN EN ISO/IEC 17025:2018 (1)
- DRIFTS (1)
- Damping factor (1)
- Definition of nanomaterial (1)
- Degradation (1)
- Density Functional Theory (1)
- Deuterium (1)
- Diffraction (1)
- Dispersion of nano materials (1)
- Domain wall (1)
- Double complex salts (1)
- Dynamic heterogeneity (1)
- Dünne Schichten (1)
- EC4SafeNano (1)
- EMPIR (1)
- Electrical conductivity (1)
- Electrochemical deposition (ECD) (1)
- Electrochemical sensing (1)
- Electromagnetic radiation (1)
- Electromagnetic scattering (1)
- Electrospun fibers (1)
- Elemental composition (1)
- Ellipsometric porosimetry (1)
- Ellipsometry (1)
- Energetic Materials (1)
- Energiedissipation im Kontakt (1)
- Epoxy conversion degree (1)
- Epoxy-Anhydrid Duroplast (1)
- Europium (1)
- Exchange length (1)
- Exposed metal sites (1)
- FTIR (1)
- FTIR spectroscopy (1)
- Facilitated activation (1)
- Fast scanning calorimeter (1)
- Fast scanning calorimetry (1)
- Fast scanning calormetry (1)
- Fe (1)
- Fe-Ni (1)
- Fiber Bragg grating (FBG) (1)
- Filters (1)
- Fluid-flow (1)
- Fluorescence (1)
- Forschungsstrategie (1)
- Friction (1)
- Fully aromatic frameworks (1)
- Functionalized nanographene (1)
- GUM-compliance (1)
- Gamma (1)
- Gas separation membranes (1)
- Geant4-DNA (1)
- Geology (1)
- Ggraphene polymer nanocomposite (1)
- Glucose (1)
- Gold (1)
- Gold Nanoparticle (1)
- Gold Nanoparticles (1)
- Graphene (1)
- Graphene Oxide (1)
- Graphene polymer nanocomposite (1)
- Grating (1)
- Grenzfläche als Material (1)
- Hamonisierung (1)
- Heating oil tanks (1)
- High specific surface area (1)
- High-entropy alloys (1)
- Human umbilical cell adhesion (1)
- Hydration (1)
- Hydrogen (1)
- Hydrothermal synthesis (1)
- Härte (1)
- IIT (1)
- IR spectroscopy (1)
- ISO (1)
- ISO 14577 (1)
- ImAFM (1)
- Infrared nano AFM (1)
- Instrumented Indentation Testing (1)
- Instrumentierte Eindringprüfung (1)
- Instrumentierte Eindringprüfung (IIT) (1)
- Inter-laborator comparison (1)
- Interfaces (1)
- Intermodulation (1)
- Intermodulation AFM (1)
- Intermodulation-AFM (1)
- Introduction (1)
- Iron (1)
- Kinetics (1)
- Knoevenagel condensation (1)
- Kompaktierbarkeit (1)
- Kompressibilität (1)
- Korrosion (1)
- Korrosionsüberwachung (1)
- Kunststoff (1)
- LC / MALDI-TOF-MS coupling (1)
- LC x ESI-TOF-MS (1)
- LC-MS (1)
- LCCC (1)
- LEVASIL 50/50 (1)
- LL equation (1)
- Lactide (1)
- Landau Lifshitz Gilbert equation (1)
- Large-pore (1)
- Laser processing (1)
- Laser-induced nanostructures (1)
- Laser-modified surface (1)
- Layer-by-layer deposition (1)
- Leichtbau (1)
- Levitation (1)
- Linear polyglycerol (1)
- Liquid Crystals (1)
- Liquid crystals (1)
- Luminescence (1)
- MALDI TOF MS (1)
- MOF-74 (1)
- MPI (1)
- MPLS (1)
- Magnet coupling (1)
- Magnetic Nanoparticles (1)
- Magnetic anisotropy (1)
- Magnetic interacion (1)
- Magnetic nanoparticle (1)
- Magnetic nanoparticles (1)
- Magnetic swimmers (1)
- Magnetization dynamics (1)
- Magnetocoloric (1)
- Martensite (1)
- Mass spectrometry (1)
- Mass spectrometry of polymers (1)
- Material Science (1)
- Material characterization (1)
- Materials Science (1)
- Materials science (1)
- Mehr-Proben-Prüfverfahren (1)
- Melting (1)
- Mesoporous Silica (1)
- Mesoporous iridium-titanium mixed oxides (1)
- Mesoporous mixed metal oxide films (1)
- Messtechnik (1)
- Messunsicherheit (1)
- Metal carbides (1)
- Metal organic framework (1)
- Metal phosphonates (1)
- Metal reducing bacteria (1)
- Metal-organic-frameworks (1)
- Methanogens (1)
- Metrology (1)
- Microanalysis (1)
- Microbeam analysis (1)
- Microbial (1)
- Microbiologically Influrenced Corrosion (MIC) (1)
- Microbiologically influenced corrosion (1)
- Microencapsulation (1)
- Microplastic (1)
- Microwave synthesis (1)
- Milling (1)
- Mixed-linkers (1)
- Modelling (1)
- Moisture (1)
- Molecular mobility (1)
- Monte-Carlo (1)
- Mueller-Matrix Ellipsometry (1)
- Multiphoton laser structuring (1)
- Multivariate data analysis (1)
- Mussel-inspired adhesives (1)
- NP (1)
- Nano (1)
- Nano particle (1)
- Nano screening (1)
- NanoValid (1)
- Nanocasting (1)
- Nanoconfinement (1)
- Nanokomposit (1)
- Nanomaterial Properties (1)
- Nanomechanical properties (1)
- Nanometrology (1)
- Nanoparticle Characterization (1)
- Nanoparticle size measurement (1)
- Nanoparticular TiO2 (Anatase) (1)
- Nanoporous (1)
- Nanorods (1)
- Nanoscale (1)
- Nanosecond laser (1)
- Nanosecond laser irradiation (1)
- Nanostructure quantification (1)
- Nanotechnologie (1)
- Neel wall (1)
- Neuartige Materialien (1)
- Ni (1)
- Nickel (1)
- Niedrigenergie-Polymeren (1)
- Nitrene[2+1]cycloaddition (1)
- Nitrides (1)
- Non-destructiv testing (1)
- Non-destructive testing (1)
- Non-destructuve testing (1)
- Non-spherical shape (1)
- Nonclassical crystallization (1)
- Oberflächenanalytik (1)
- Oberflächenmesstechnik (1)
- Oberflächenpotential (1)
- Oberflächensteifigkeit (1)
- Oberflächentechnik (1)
- Optical fibers (1)
- Optical near field (1)
- Ordered mesoporous silica (1)
- Oxocobaltates (1)
- Oxygen Evolution Catalyst (1)
- Oxygen evolution reaction (1)
- Oxygen evolution reaction (OER) (1)
- Oxygen reduction reaction (1)
- P25 (1)
- PC characterisation (1)
- Pair Distribution Functions (1)
- Paramagnetism (1)
- Particle (1)
- Particle accretion (1)
- Particle size (1)
- Phase mask (1)
- Phase transition (1)
- Phosphinine (1)
- Phosphonates (1)
- Phosphorus (1)
- Photocuring (1)
- Photooxidation (1)
- Plasmon resonance (1)
- Plasmonic nanofocusing spectroscopy (1)
- Plastikstrategie (1)
- Polarization spectroscopy (1)
- Polyethylene glycol (1)
- Polymer aging (1)
- Polymer-based nanocomposites (1)
- Polymeric membrane (1)
- Polypropylene (1)
- Pore size tailoring (1)
- Post-modification by L-cysteine (1)
- Practical aspects (1)
- Pre-standardisation (1)
- Prediction (1)
- Protein (1)
- Proton cunductor (1)
- Prüftechnik (1)
- Qualitätssicherung (1)
- ROPPOC (1)
- Radiation damage (1)
- Radioactive NP (1)
- Real-time infrared spectroscopy (1)
- Reconstructed ion chromatograms (1)
- Recycling (1)
- Recycling-by-design (1)
- Reference Nanomaterials (1)
- Regulation (1)
- Resonance (1)
- Rh-Ir alloys (1)
- Rietveld (1)
- Ring-expansion polymerization (1)
- Ring-opening polymerization (1)
- Risstrajektorie (1)
- Rosin (1)
- SEC (1)
- SEM (1)
- SEM/EDS/STRATAGem (1)
- SIMS (1)
- SKPM (1)
- Salicylate (1)
- Scanning electrochemical microscope (SECM) (1)
- Scattering (1)
- Self-lubricating coating (1)
- Service life (1)
- Shape-controlled (1)
- Si-Ge (1)
- Silane (1)
- Single-source precursors (1)
- Size distribution (1)
- Small-angle x-ray scattering (1)
- Sonochemical synthesis (1)
- Specific Surface Area (BET) (1)
- Spectroscopic Imaging (1)
- Spektrale Ellipsometrie (SE) (1)
- Spin (1)
- Spontaneous emulsification (1)
- Stand der Normung (1)
- Standardization (1)
- Standardization of Ellipsometry (1)
- Steel (1)
- Stereocomplex (1)
- Stimuli-responsive polymers (1)
- Stochastic Landau Lifshitz equation (1)
- Structural defects (1)
- Structures under extreme conditions (1)
- Struvite (1)
- Sulfidation (1)
- Sulfur (1)
- Superparamagnetism (1)
- Surface Chemical Transformation (1)
- Surface characterization (1)
- Surface charge (1)
- Surface structures (1)
- Suzuki-Miyaura coupling (1)
- Synchrotron CT (1)
- Synchrotron radiation (1)
- TGA-FTIR (1)
- Tara Mediterranee (1)
- Temperature effects (1)
- Temperature modulated differential scanning calorimetry (1)
- Tensile Stress (1)
- Thermal extraction-desorption gas chromatography mass spectrometry (1)
- Thermo-responsive polymers (1)
- Thermogravimetry (1)
- Thermoplastics (1)
- Thin film systems (1)
- TiO2 (1)
- TiO2 nanoparticle (1)
- Tin(II)octanoate (1)
- Titanium dioxide (1)
- ToF-SIMS (1)
- Topometry (1)
- Topotactic phase transitions (1)
- Total scattering analysis (1)
- Toxicity (1)
- Transformation pathways (1)
- Tribology (1)
- Two-Photon Polymerization (1)
- Two-dimensional hexagonal boron nitride(h-BN) (1)
- UCST polymers (1)
- UV Weathering (1)
- Ultrafast scattering (1)
- Ultrashort laser pulses (1)
- Uncertainty budget (1)
- Uncertainty budgets (1)
- Wastewater (1)
- Wear (1)
- Weißlichtinterferenzmikroskopie (WLIM, 3D) (1)
- White light interference microscopy(WLIM) (1)
- X-Ray Imaging (1)
- X-Ray imaging (1)
- X-ray Absorption Spectroscopy (1)
- X-ray Photoelectron Spectroscopy (XPS) (1)
- X-ray absorption spectroscopy (1)
- X-ray imaging (1)
- X-ray spectroscopic techniques (1)
- X-ray spectroscopy (1)
- XAFS (1)
- XANES (1)
- Zeolitic Imidazolate Frameworks (1)
- Zeta potential (1)
- Zinc oxide (1)
- attraktive Wechelwirkung (1)
- beta particle (1)
- clustered nanoparticles (1)
- dielectric spectroscopy (1)
- gamma ray (1)
- gas separation membranes (1)
- mechanical properties (1)
- molecular mobility (1)
- nanoindentation (1)
- performance test (1)
- polymers (1)
- polymers of intrinsic microporosity (1)
- polynorbornenes (1)
- product specification (1)
- radiolysis (1)
- shape control (1)
- temeprature dependent exchange length (1)
- uncertainty (1)
- µ-XRF (1)
Organisationseinheit der BAM
- 6 Materialchemie (229) (entfernen)
Eingeladener Vortrag
- nein (95)
To arrive to sustainable hydrogen-based energy solutions, the understanding of water-splitting catalysts plays the most crucial role. Herein, state-of-the-art hypotheses are combined on electrocatalytic active metal sites toward the oxygen evolution reaction (OER) to develop a highly efficient catalyst based on Earth-abundant cobalt and zinc oxides.
The precursor catalyst Zn0.35Co0.65O is synthesized via a fast microwaveassisted approach at low temperatures. Subsequently, it transforms in situ from the wurtzite structure to the layered γ-Co(O)OH, while most of its zinc leaches out. This material shows outstanding catalytic Performance and stability toward the OER in 1 m KOH (overpotential at 10 mA cm−2 ηinitial = 306 mV, η98 h = 318 mV). By comparing the electrochemical results and ex situ analyses to today’s literature, clear structureactivity correlations are able to be identified. The findings suggest that coordinately unsaturated cobalt octahedra on the surface are indeed the active centers for the OER.
Das Fügeverfahren Kleben bietet viele Vorteile, wie z.B. das Verbinden unterschiedlicher Materialklassen, geringe thermische Belastung (und damit ggf. verbundene Strukturveränderung/-schwächung) der Fügeteile und eine Lastverteilung über den gesamten Fügebereich. Die Auswahl an verfügbaren Klebstoffen und Vorbehandlungsoptionen sind dabei - wie die Applikationen auch - vielfältig. Es werden vier Applikationsbeispiele zu Referenzklebverbunden aus Edelstahl, zur Plasmaaktivierung von Niedrigenergie-Polymeren, zur Bestimmung der Haftfestigkeit von Lackierungen auf GFK und zur Wirkung von Primern vorgestellt. Einige Polymere weisen z.B. Eigenschaften auf, die eine Herstellung von festen und dauerhaft beanspruchbaren Kleb-verbindungen erschweren. Im Allgemeinen geht dies mit geringen Oberflächenenergien einher. Mittels Oberflächenvorbehandlung, z.B. durch Plasmafeinreinigung bzw. Plasmaaktivierung, können die Grenzflächen solcher Polymere - bezogen auf die Eignung als Fügeteile (Klebfestigkeit) oder als Substrat (Haftfestigkeit) – optimiert bzw. die Oberflächenenergie erhöht werden. Schnelle, zuverlässige und statistisch abgesicherte Prüfverfahren zur Ermittlung von Verbund-eigenschaften sind dabei unverzichtbar.
Das Fügeverfahren Kleben bietet viele Vorteile wie z.B. das Verbinden schwieriger Materialklassen, geringe thermische Belastung (Strukturveränderung/-schwächung) der Fügepartner und eine Lastverteilung über den gesamten Fügebereich. Die Auswahl an verfügbaren Klebstoffen und Vorbehandlungsoptionen ist dabei ebenfalls vielfältig. Einige Polymere weisen darüber hinaus Eigenschaften auf, die eine Herstellung von festen und dauerhaft beanspruchbaren Klebverbindungen erschweren. Mittels Oberflächenbehandlung, z.B. durch Plasmafeinreinigung bzw. –aktivierung, können die Grenzflächern solcher Polymere - bezogen auf die Eignung als Fügeteilpartner – optimiert werden. Schnelle Prüfverfahren zur Ermittlung von Verbundeigenschaften sind somit erforderlich.
Das Messprinzip Centrifugal Adhesion Testing Technologie verwendet die radial gerichtete Zentrifugalkraft als Belastungsgröße des zu testenden Verbunds, die durch Variation der Drehzahl gesteuert wird. Bei Erreichen der kritischen Beanspruchung trennt sich ein aufgeklebter Prüfstempel vom Substrat. Zeitgleich wird ein positionsbezogenes IR-Signal aus dem drehenden Rotor an das Basisgerät gesendet und zusammen mit der Drehzahl an die PC-Software übertragen. Für jede Probe wird die Bruchkraft berechnet und in Echtzeit angezeigt. Der Adhesion Analyser LUMiFrac® untersucht bis zu acht Prüfkörper unter identischen Bedingungen. Das neue Messprinzip erfüllt die Anforderungen von DIN EN 15870, DIN EN 14869-2, ISO 4624 sowie DIN EN 13144.
Die Multiprobentestung ermöglicht schnelle Charakterisierungen von Klebverbindungen. So kann der Effekt einer Plasmabehandlung von Bauteilen auf die Verbundfestigkeit zeitsparend bestimmt werden. Die gezielte Veränderung unterschiedlicher Plasma-Parameter, wie beispielsweise, die Plasmazusammensetzung, der Abstand vom Plasmabrenner zur Oberfläche oder die Verweildauer unter dem Brenner, beeinflußt die Festigkeit des Klebsystems und ist dem LUMiFrac direkt quantifizierbar.
Neben der Festigkeitsbestimmung von Klebverbindungen ist die Haftung von Schichtsystemen ein wichtiger Anwendungsbereich. Ergebnisse für Zug- und Scherbeanspruchung, realisiert mit unterschiedlichen Prüfkörper-Geometrien, werden vorgestellt. Ferner werden verschiedene festigkeitsbeeinflussende Faktoren, wie Prüfgeschwindigkeit oder Substratverformung bei Beanspruchung untersucht
Using magnetic materials for energy conversion as an example, this lecture shows how X-ray tomography investigations can contribute to structure elucidation in composites and solid samples. The components are tested non-destructively in order to characterize cracks, pores and other defects and their influence on the functional properties three-dimensionally and in good time in the life cycle of the material. If you combine microtomography with other methods of magnetic material characterization, you can make unique statements about the structure and the functional properties.
Using magnetic materials for energy conversion as an example, this lecture shows how X-ray tomography investigations can contribute to structure elucidation in composites and solid samples. The components are tested non-destructively in order to characterize cracks, pores and other defects and their influence on the functional properties three-dimensionally and in good time in the life cycle of the material. If you combine microtomography with other methods of magnetic material characterization, you can make unique statements about the structure and the functional properties.
Functional materials for energy conversion are important technology drivers needed for the implementation of low carbon energy. Therefore, researchers commonly focus on improving the intrinsic properties of a functional material. However, for applications, the extrinsic properties are at least as important as the intrinsic ones. Consequently, it is important to investigate and understand the external and internal structure of semi-finished products and especially defect dependent properties. The extrinsic properties may change during application and the life cycle of the material as well as through processing and molding steps.
Our studies show how X-ray tomographic (XCT) investigations can contribute to structure investigations in composites and massive samples using the example of magnetic materials for energy conversion. The components are tested non-destructively in 3D in order to localize and characterize cracks, pores, inclusions as well as other defects and their influence on the functional properties and also “in-time” during the life cycle of the material. Exsitu and in-situ experiments performed with non-destructive XCT are predestinated to follow damaging mechanisms of materials under certain load conditions, atmospheres or liquids, e.g. went through several working cycles of a functional material. By combining microtomography with other methods of magnetic and classical material characterization, unique statements about the structure and the functional properties can be made.
From the applications point of view, sometimes complex, three-dimensional geometries are needed to fully exploit the functional properties of the materials, e.g. to ensure a high surface area for heat exchange. Since many functional materials are brittle and difficult to form, shaping is often a big challenge. In principle, additive manufacturing processes offer the possibility to produce complex, porous components from poorly formable alloys.
If all stages of additive manufacturing are accompanied by X-ray tomographic imaging, the process of finding the optimal parameters for material processing can be significantly accelerated.
Based on the quality control of the initial powder material used and also investigations of the shape and arrangement of defects within the molten structure and their relationship with the melting path scanning strategy, Xray tomography has proven to be an ideal tool for additive manufacturing, even for functional materials. Overall, tomographic methods are important tools for the development of functional materials to application maturity.
The industrial use of ultrashort laser pulses has made considerable progress in recent years. The reasons for this lie in the availability of high average powers at pulse repetition rates in the several 100 kHz range. The advantages of using ultrashort laser pulses in terms of processing precision can thus be fully exploited. However, high laser intensities on the workpiece can also lead to the generation of unwanted X-rays. Even if the emitted X-ray dose per pulse is low, the accumulated X-ray dose can become significant for high-repetition-rate laser systems so that X-ray exposure safety limits must be considered. The X-ray emission during ultrashort pulse laser processing was investigated for a pulse duration of 925 fs at 1030 nm wavelength and 400 kHz repetition rate. Industrially relevant materials such as steel, aluminum and glass were treated. Tungsten served as reference. X-ray spectra were recorded, and X-ray dose measurements were performed for laser treatment in air. For laser intensities > 2 × 10^13 W/cm2, X-ray doses exceeding the regulatory exposure limits for members of the public were found. Suitable X-ray protection strategies are proposed.
The industrial use of ultrashort laser pulses has made considerable progress in recent years. The reasons for this lie in the availability of high average powers at pulse repetition rates in the several 100 kHz range. The advantages of using ultrashort laser pulses in terms of processing precision can thus be fully exploited. However, high laser intensities on the workpiece can also lead to the generation of unwanted X-rays. Even if the emitted X-ray dose per pulse is low, the accumulated X-ray dose can become significant for high-repetition-rate laser systems so that X-ray exposure safety limits must be considered. The X-ray emission during ultrashort pulse laser processing was investigated for a pulse duration of 925 fs at 1030 nm wavelength and 400 kHz repetition rate. Industrially relevant materials such as steel,aluminum and glass were treated. Tungsten served as reference. X-ray spectra were recorded, and X-ray dose measurements were performed for laser treatment in air. For laser intensities > 2 × 10^13 W/cm2, X-ray doses exceeding the regulatory exposure limits for members of the public were found. Suitable X-ray protection strategies are proposed.
Ultrashort laser pulse micromachining features a high precision. By increasing the repetition rate of the applied laser to several 100 kHz, laser processing becomes quick and cost-effective and make this method attractive for industrial applications. Upon exceeding a critical laser intensity, hard X-ray radiation is generated as a side effect. Even if the emitted X-ray dose per pulse is low, the accumulated X-ray dose becomes significant for high-repetition-rate laser systems so that radiation safety must be considered.
Water as side effect of reinforcing boehmite filler Local changes in anhydride cured epoxy resin
(2019)
Nanocomposites offer wide opportunities for lightweight constructions and enable reduction of weight and volume. Beside macroscopic toughening nanoparticle reinforced polymers show a soft interface around boehmite (AlOOH) filler nanoparticles. A related strong interaction between boehmite and the anhydride cured resin system is widely suspected in literature but not determined by structural Analysis. Determination of the molecular structure is important to allow simulations approaching the real system and predict future reinforcing effects.
DRIFT (diffuse refletance infrared fourier transformed) spectra of the boehmite reinforced anhydride cured epoxy show significant changes in the molecular structure compared to the neat polymer. Further investigations of the interactions between the single components of the resin system and the boehmite filler pointed out reactions between released water released from the boehmite filler and the anhydride hardener or amine accelerator. This leads to the discussion of competing polymerisation mechanisms that highly influence the polymer properties. Ongoing experiments and literature research approve that this impact of water is able to locally change the stoichiometrie, alter the curing mechanism or support an inhomogeneous crosslink density.
Visualisierung von mikro- und nanoskalierten Oberflächenstrukturen mittels abbildender Ellipsometry
(2019)
In den letzten Jahren hat die Einbindung der abbildenden Ellipsometrie in die Gruppe der optischen Verfahren zur Oberflächencharakterisierung ein enormes Potential bei der Analyse von topologischen Strukturänderungen gezeigt. Der dabei abgebildete Kon-trast wurde typischerweise auf Änderungen im Brechungsindex, Absorptionseffekte oder Schichtdickenänderungen zurückgeführt. In späteren Studien wurde festgestellt, dass auch andere Faktoren, wie etwa die Krümmung der Oberfläche oder Kanten von Struktu-ren einen signifikanten Einfluss auf die Messung der ellipsometrischen Paramater haben. Um diese Effekte aus der ellipsometrischen Messung extrahieren zu können, wird auf die Analyse der Müller-Matrix zurückgegriffen.
In dem hier vorliegenden Beitrag wird gezeigt, wie die Müller-Matrix-Imaging Ellipsomet-rie (MM-IE) zur Charakterisierung von Oberflächenstrukturen verwendet werden kann. Dazu werden mikro- und nanoskaliert gekrümmte Oberflächen zunächst mit verschiede-nen Referenzmethoden, wie Rasterelektronenmikroskopie (SEM), Lichtmikroskopie (OM), Weißlichtinterferenzmikroskopie (WLIM) und Rasterkraftmikroskopie (AFM) vali-diert erfasst. Der anschließende Vergleich mit den Ergebnissen der Müller-Matrix-Ima-ging-Ellipsometrie ermöglicht eine Korrelation der zugrunde liegenden Strukturphäno-mene mit den ellipsometrischen Daten. In diesem Artikel wird das Prinzip an drei industriell relevanten Strukturgruppen demonstriert: Sub-Mikropartikel, Mikropartikel und sub-mikroskalierte Vertiefungen.
Visualisierung von mikro- und nanoskalierten Oberflächenstrukturen mittels abbildender Ellipsometrie
(2019)
In den letzten Jahren hat die Einbindung der abbildenden Ellipsometrie in die Gruppe der optischen Verfahren zur Oberflächencharakterisierung ein enormes Potential bei der Analyse von topologischen Strukturänderungen gezeigt. Der dabei abgebildete Kon-trast wurde typischerweise auf Änderungen im Brechungsindex, Absorptionseffekte oder Schichtdickenänderungen zurückgeführt. In späteren Studien wurde festgestellt, dass auch andere Faktoren, wie etwa die Krümmung der Oberfläche oder Kanten von Struktu-ren einen signifikanten Einfluss auf die Messung der ellipsometrischen Paramater haben. Um diese Effekte aus der ellipsometrischen Messung extrahieren zu können, wird auf die Analyse der Müller-Matrix zurückgegriffen.
In dem hier vorliegenden Beitrag wird gezeigt, wie die Müller-Matrix-Imaging Ellipsomet-rie (MM-IE) zur Charakterisierung von Oberflächenstrukturen verwendet werden kann. Dazu werden mikro- und nanoskaliert gekrümmte Oberflächen zunächst mit verschiede-nen Referenzmethoden, wie Rasterelektronenmikroskopie (SEM), Lichtmikroskopie (OM), Weißlichtinterferenzmikroskopie (WLIM) und Rasterkraftmikroskopie (AFM) vali-diert erfasst. Der anschließende Vergleich mit den Ergebnissen der Müller-Matrix-Ima-ging-Ellipsometrie ermöglicht eine Korrelation der zugrunde liegenden Strukturphäno-mene mit den ellipsometrischen Daten. In diesem Artikel wird das Prinzip an drei industriell relevanten Strukturgruppen demonstriert: Sub-Mikropartikel, Mikropartikel und sub-mikroskalierte Vertiefungen.
View into the depths of copolymer microstructure by a special approach of LC-MS data evaluation
(2019)
It is a well-known story that copolymers beside their molar mass distribution (MMD) can exhibit a functionality type distribution (FTD), a copolymer composition distribution (CCD), a monomer sequence distribution (MSD) and additionally different topologies within one sample. This is and will remain a challenge for analysts.
First a very short overview will be given concerning the common liquid separation techniques for polymers (SEC, LAC, LCCC, GELC) coupled to soft ionization mass spectrometric methods like MALDI and ESI-MS with focus on their limitations. For very broadly distributed samples or chemical very similar species the superposition of different separation mechanisms in chromatography is unavoidable or the separation efficiency cannot be optimized.
Different ionization probabilities and species of the same nominal mass with completely different structures are just two problems of mass spec of complex polymer mixtures.
Subsequently, different examples will be shown how these limitations in some cases could be outsmarted.
First example will be the separation of statistical EO-PO copolymers of different chemical compositions by end group functionality and the quantification of end group fractions over the whole CCD. Here an UP-LCCC / ESI-TOF-MS coupling is applied.
Further for different kinds of polymers it will be shown how it could be realized to obtain information on small isobaric/isomeric topological heterogeneities by coupling UP-SEC / ESI-TOF-MS.
All results are based on the data processing of reconstructed ion chromatograms of single mass traces of complex ESI-MS spectra.
Thermosetting materials are gaining increasing attention in many structural composite applications. However, the incorporation of inorganic nanoparticles (NPs) into polymer matrix is a promising approach to enhance their functional characteristics, and thus, to enable the development of thermosets advanced application. It has been shown that Boehmite Alumina (BA) used as nanofillers can improve different parameters of polymers. This NPs can be easily tailored enabling desirable interactions with a big range of polymers. However, the overall effect of nanofiller depends on many factors, therefore, making it hard to predict the resulted performance of nanocomposites. In the current contribution we would like to discuss the impact of Boehmite NPs on two different epoxy resin nanocomposite systems with the focus on the possible influence mechanisms of this nanofiller.
As the first system, UV curable Cycloaliphatic-Epoxy Oligosiloxane (CEOS) resin/Boehmite nanocomposites were investigated by FTIR, TGA, DSC and T-SEM. It was observed that incorporation of BA leads to the reinforcement of glass transition (Tg) and overall thermal stability indicating the attractive interactions between BA and CEOS network. In addition, an increase in epoxy conversion of CEOS was concluded for nanocomposites assuming that particles are involved in UV polymerisation processes.
The second epoxy/Boehmite nanocomposite is based on the bisphenol-A-diglycidyl ether (DGEBA) cured with methyl tetrahydrophtalic acid anhydride (MTHPA). Thermomechanical as well as nanomechanical properties of this material were investigated by DMTA and IR spectroscopy and the advanced Intermodulation AFM, respectively. In contrast to the first system, it was found that BA leads to a decrease of Tg and crosslink density of the polymer while the young’s modulus of the composite and local stiffness of polymer matrix increase significantly.
As a result, the versatile role of Boehmite was detected depending on the investigated systems. Based on the obtained results, the parameters indicating property-efficient epoxy/Boehmite system are suggested.
The coherent exchange of optical near fields between two neighbouring dipoles plays an essential role in the optical properties, quantum dynamics and thus the function of many naturally occurring and artificial nanosystems. These interactions are challenging to quantify experimentally. They extend over only a few nanometres and depend sensitively on the detuning, dephasing and relative orientation (that is, the vectorial properties) of the coupled dipoles. Here, we introduce plasmonic nanofocusing spectroscopy to record coherent light scattering spectra with 5 nm spatial resolution from the apex of a conical gold nanotaper.
The apex is excited solely by evanescent fields and coupled to plasmon resonances in a single gold nanorod. We resolve resonance energy shifts and line broadenings as a function of dipole distance and relative orientation. We demonstrate how These phenomena arise from mode couplings between different vectorial components of the interacting optical near fields, specifically from the coupling of the nanorod to both transverse and longitudinal polarizabilities of the taper apex.
The transformation of a base-catalyzed, mechano-assisted Knoevenagel condensation of mono-fluorinated benzaldehyde derivatives (p-, m-, o-benzaldehyde) with malonodinitrile was investigated in situ and in real time. Upon milling, the para-substituted product was found to crystallize initially into two different polymorphic forms, depending on the quantity of catalyst used. For low catalyst concentrations, a mechanically metastable phase (monoclinic) was initially formed, converting to the mechanically stable phase (triclinic) upon further grinding. Instead, higher catalyst concentrations crystallize directly as the triclinic product. Inclusion of catalyst in the final product, as evidenced by mass spectrometric analysis, suggests this complex polymorphic pathway may be due to seeding effects. Multivariate analysis for the in situ Raman spectra supports this complex formation pathway, and offers a new approach to monitoring multi-phase reactions during ball milling.
We here explore how ball-mill-grinding frequency affects the kinetics of a disulfide exchange reaction. Our kinetic data show that the reaction progress is similar at all the frequencies studied (15–30 Hz), including a significant induction time before the nucleation and growth process starts. This indicates that to start the reaction an initial energy accumulation is necessary. Other than mixing, the energy supplied by the mechanical treatment has two effects: (i) reducing the crystal size and (ii) creating defects in the structure. The crystal-breaking process is likely to be dominant at first becoming less important later in the process when the energy supplied is stored at the molecular level as local crystal defects. This accumulation is taken here to be the rate-determining step. We suggest that the local defects accumulate preferentially at or near the crystal surface. Since the total area increases exponentially when the crystal size is reduced by the crystal-breaking process, this can further explain the exponential dependence of the onset time on the milling frequency.
Im Vortrag wird die Problematik Mikroplastik eingeführt und ein Probenset aus dem Mittelmeer mit ersten Ergebnissen besprochen. Die Alterung von Polymeren im Umweltkontext sowie Möglichkeiten der Analyse von Polymeralterungsfortschritten werden diskutiert. Die thermoanalytische Methode mit Zersetzungsgasanalytik (TED-GC-MS) wird eingeführt und deren Einsatzmöglichkeiten in der Thematik umrissen.