5 Werkstofftechnik
Filtern
Dokumenttyp
- Zeitschriftenartikel (55) (entfernen)
Sprache
- Englisch (55) (entfernen)
Referierte Publikation
- nein (55) (entfernen)
Schlagworte
- Corrosion (8)
- Additive manufacturing (6)
- Additive Manufacturing (4)
- CCS (4)
- Steel (4)
- Corrosion Fatigue (3)
- High alloyed steel (3)
- Alkali zinc borate glasses (2)
- Aquifer (2)
- Binder Jetting (2)
- Carbon storage (2)
- Corrosion fatigue (2)
- Creep (2)
- Crystallization (2)
- Damage (2)
- Glass (2)
- Heat treatment (2)
- High Alloyed Steel (2)
- Layerwise Slurry Deposition (2)
- Lead borate glasses (2)
- Nanoparticles (2)
- Pitting (2)
- Solubility (2)
- X-ray diffraction (2)
- 150 Years (1)
- 2PP (1)
- 3D-printing (1)
- ATZ (1)
- Acid-leaching (1)
- Additive manufactured Ni-base superalloys (1)
- Adolf Martens (1)
- Advanced wastewater treatment (1)
- Agglomerates (1)
- Aging (1)
- Al2O3 (1)
- Alkali-activated materials (1)
- Alpha-tricalcium phosphate (1)
- Alumina toughened zirconia (1)
- Aluminosilicate glasses (1)
- Aluminum alloy (1)
- Amorphous silica (1)
- Annealing (1)
- Bio-ceramic engineering (1)
- Bioactive glass (1)
- Blended learning (1)
- Bond energy (1)
- Brown-rot fungi (1)
- CALPHAD (1)
- Cabon capture and storage (1)
- Carbidic austempered ductile iron (1)
- Carbon capture and storage (1)
- Ccs (1)
- Ceramic (1)
- Ceramic nano particles (1)
- Ceramics (1)
- Ceramics 3D printing (1)
- Co2-Storage (1)
- Coating (1)
- Composite (1)
- Coniophora puteana (1)
- Corrosion mechanism (1)
- Coulomb explosion (1)
- CrMnFeCoNi (1)
- Crack propagation (1)
- Critical energy release rate (1)
- Crystal lattice (1)
- Crystal plasticity (1)
- Cubical shape (1)
- Cytocompatibility (1)
- Defect detection (1)
- Density-based Model (1)
- Dentine (1)
- Diffusion (1)
- Diffusivity (1)
- Dispersion process (1)
- Diversity (1)
- Ductile iron (1)
- EBSD (1)
- Electrochemical deposition (1)
- Electron beam-induced fragmentation (1)
- Electron diffraction (1)
- Electron microscopy (1)
- Enamel (1)
- Endurance Limit (1)
- Environmentally assisted cracking (1)
- Fatigue (1)
- Fluoride nanoparticles (1)
- Fluorolytic sol−gel (1)
- Fourier transform infrared spectroscopy (1)
- Fracture mechanics (1)
- Fracture surface energy (1)
- Fragility (1)
- Functional fatigue (1)
- Gas flow assisted powder deposition (1)
- General Chemistry (1)
- Geometrical factors (1)
- Glass fiber reinforced polymer (1)
- Glass liner (1)
- Glass powder (1)
- Grain boundary engineering (1)
- High Cycle Fatigue (1)
- High entropy alloy (1)
- High-temperature corrosion (1)
- Hot isostatic pressing (HIP) (1)
- Hybrid Manufacturing (1)
- Hydrogen permeation (1)
- Hydrogen storage tank (1)
- IR spectroscopy (1)
- In-situ diffraction (1)
- Inconel 625 (1)
- Indentation hardness (1)
- Interface (1)
- Interfacial shear strength (1)
- Inverted classroom (1)
- Ionic porosity (1)
- Iron oxide (1)
- Kikuchi diffraction (1)
- Laser ablation in liquid (1)
- Laser-induced slip casting (1)
- Lattice misfit (1)
- Lattices (1)
- Lecture films (1)
- Lifetime prediction (1)
- Lithography-based technologies (1)
- Lorenz transmission electron microscopy (1)
- Martensitic steel (1)
- Mass transport (1)
- Materials Chemistry (1)
- Mechanical Engineering (1)
- Mechanics of Materials (1)
- Metals and Alloys (1)
- Microsegregation (1)
- Microstructure (1)
- Microstructure Design (1)
- Molecular Dynamics (1)
- Molecular dynamics (1)
- Nano CRM (1)
- Nano-ceramic-additive-manufacturing photoresin (1)
- Nano-powder (1)
- NanoCAM (1)
- Networking (1)
- Ni-Mn-Ga (1)
- Niobium alloying (1)
- Nucleation tendency (1)
- Particle morphology (1)
- Pattern matching (1)
- Permeability (1)
- Phase-field (1)
- Physical properties (1)
- Phytolith (1)
- Polyaniline (1)
- Polymer matrix composites (1)
- Polymer-ceramic mixtures (1)
- Porosity (1)
- Portfolio (1)
- Powder bed density (1)
- Powder-based processes (1)
- Powdered activated carbon (1)
- Process (1)
- Pull-out composite materials (1)
- Quality assurance (1)
- Raman spectroscopy (1)
- Reference nanoparticles (1)
- Resistance stress (1)
- Rhodonia placenta (1)
- Roughness (1)
- SAXS (1)
- SEM wood characterization (1)
- Scaffold (1)
- SchwarzP cells (1)
- Segregation Engineering (1)
- Sewage treatment plant (1)
- Shape-memory alloys (1)
- Single crystal superalloys (1)
- Sinter retardation (1)
- Sintering (1)
- Size (1)
- Sliding simulation (1)
- Slip-rolling (1)
- Slurry (1)
- Space (1)
- Steels (1)
- Superelasticity (1)
- Superlattice extrinsic stacking faults (1)
- Surface (1)
- Surface roughness (1)
- Surface-induced Melting (1)
- Technical Ceramics (1)
- Temperature (1)
- Thermo-mechanics (1)
- Thermoanalysis (1)
- Thermogravimetry (1)
- Thin tribofilm (1)
- Titanium oxide (1)
- Tooth wear (1)
- Transmission electron microscopy (1)
- Two-photon adsorption (1)
- Two-photon polymerization (1)
- Vacancies (1)
- Viscosity (1)
- Viscous sintering (1)
- Wood protection (1)
- Young’s Modulus (1)
- bioactive (1)
- biomaterials (1)
- bone (1)
- corrosion (1)
- high entropy alloys (1)
- hydrogen storage (1)
- oxidation (1)
- scanning electron microscopy (1)
- sulfidation (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (55) (entfernen)
The process of viscous flow sintering is a phenomenon that is closely linked to the surface properties of the glass particles. In this work, we studied the extreme case of acid-leaching of soda-lime-silicate glass beads of two different particle size distributions and its effects on non-isothermal viscous sintering of powder compacts. Depth profiling of the chemical composition after leaching revealed a near-surface layer depleted in alkali and alkaline earth ions, associated with concurrent hydration as mass loss was detected by thermogravimetry. Heating microscopy showed that acid treatment of glasses shifted the sinter curves to higher temperatures with increasing leaching time. Modelling of the shrinkage with the cluster model predicted a higher viscosity of the altered surface layer, while analysis of the time scales of mass transport of mobile species (Na+, Ca2+ and H2O) during isochronous sintering revealed that diffusion of Na+ can compensate for concentration gradients before sintering begins. Also, exchanged water species can diffuse out of the altered layer, but the depletion of Ca2+ in the altered surface layer persists during the sinter interval, resulting in a glass with higher viscosity, which causes sintering to slow down.
To mitigate carbon dioxide emissions CO2 is compressed and sequestrated into deep geological layers (Carbon Capture and Storage CCS). The corrosion of injection pipe steels is induced when the metal is in contact with CO2 and at the same time the geological saline formation water. Stainless steels X35CrMo17 and X5CrNiCuNb16-4 with approximately 17% Cr show potential as injection pipes to engineer the Northern German Basin geological onshore CCS-site. Static laboratory experiments (T = 60 ◦C, p = 100 bar, 700–8000 h exposure time, aquifer water, CO2-flow rate of 9 L/h) were conducted to evaluate corrosion kinetics. The anomalous surface corrosion phenomena were found to be independent of heat treatment prior to exposure. The corrosion process is described as a function of the atmosphere and diffusion process of ionic species to explain the precipitation mechanism and better estimate the reliability of these particular steels in a downhole CCS environment.
In this study, the thermomechanical damage behavior of a glass fiber reinforced polymer material is investigated. The coefficients of thermal expansion of the composite as well as the matrix are measured in a wide temperature range. Quasi-static experiments with neat resin, unidirectional and multidirectional laminates are performed as well as fatigue experiments in a temperature range from 213 K to 343 K. This study focusses on the matrix damage due to fiber-parallel loading. A correlation between matrix effort, the dilatational strain energy of the matrix and the damage state of the specimen is demonstrated. It is shown that a fatigue life assessment can be performed with the aid of a temperature-independent master fatigue curve.
Corrosion fatigue specimen with different surfaces (technical surfaces after machining and polished surfaces) of high alloyed martensitic stainless steel X46Cr13 (1.4043) and duplex stai nless steel X2CrNiMoN22 3 2 (1.4462) were compared at load amplitudes from 175 MPa to 325 MPa in the geothermal brine of the N orthern German Basin at 98 °C. Surface corrosion layers and pits reveal carbonate corrosion products on the surface such as FeCO 3 and FeOOH as the main precipitation phases with no dependence on the original surface roughness . At high stress amplitudes above 275 MPa technical surfaces (P50% at σa 300 MPa=5 × 10 5 ) resulted in more cycles to failure than polished (P50% at σa 300 MPa=1.5 × 10 5 ). The greater slope coefficient for technical surfaces k = 19.006 compared to polished surfaces k =8.78 demonstrate s earlier failure at given stress amplitude σa .
BAM is currently building up a platform of novel nanoRMs relying on iron oxide nanoparticles of different shape, size and surface chemistry. Iron oxide was chosen as a core material because of its relevance to the material and life sciences.
As a first candidate of this series, we present cubic iron oxide nanoparticles with a nominal edge length of 8 nm. These particles were synthesized by thermal decomposition of iron oleate in high boiling organic solvents adapting well-known literature procedures. After dilution to a concentration suitable for electron microscopy (TEM and SEM) as well as for small-angle X-ray scattering (SAXS) measurements, the candidate nanoRM was bottled and assessed for homogeneity and stability by both methods following the guidelines of ISO 17034 and ISO Guide 35.
The particle sizes obtained by both STEM-in-SEM and TEM are in excellent agreement with a minimum Feret of 8.3 nm ± 0.7 nm. The aspect ratio (AR) of the iron oxide cubes were extracted from the images as the ratio of minimum Feret to Feret resulting in an AR of 1.18 for TEM to 1.25 for SEM. Alternatively, a rectangular bounding box was fitted originating from the minimum Feret and the longest distance through the particle in perpendicular direction. This led to AR values of 1.05 for TEM and 1.12 for SEM, respectively. The results confirm the almost ideal cubic shape.
BAM! This issue of Advanced Engineering Materials celebrates 150 years of scientific and technical research at the interface between academia, industry and politics. Rooted in 1871 at the birth of the German Empire and at that time located in simple basements and barracks, the institutional development began around mechanical metallurgy of iron and steel and represents today a diverse portfolio of fore-front research that orients itself along tomorrow's societal challenges and long-term research horizons.
Spherical mesoporous bioactive glasses in the silicon dioxide (SiO2)-phosphorus pentoxide (P2O5)–calcium oxide (CaO) system with a high specific surface area of up to 300m2/g and a medium pore radius of 4 nm were synthesized by using a simple one-pot surfactant-assisted sol–gel synthesis method followed by calcination at 500–700°C. The authors were able to control the particle properties by varying synthesis parameters to achieve microscale powders with spherical morphology and a particle size of around 5–10 mm by employing one structure-directing agent. Due to a high Calcium oxide content of 33·6mol% and a phosphorus pentoxide content of 4·0mol%, the powder showed very good bioactivity up to 7 d of immersion in simulated Body fluid. The resulting microspheres are promising materials for a variety of life science applications, as further processing – for example, granulation – is unnecessary. Microspheres can be applied as materials for powder-based additive manufacturing or in stable suspensions for drug release, in bone cements or fillers.
Functional fatigue of shape-memory alloys is a considerable threat to the reliable service of actuation devices. Here, we demonstrate the essentially degradation-free cyclic phase-transformation behavior of Ni-Mn-Ga microcrystals up to one million stress-driven superelastic cycles. Cyclic dissipation amounts to about 1/5 of the bulk counterpart and remains unaffected during cycling, even after the introduction of dislocation structures via plastic straining. Plastic yielding and the transformation stress largely exceed the known bulk values. However, the transformation-stress is found to depend on plastic pre-straining, which suggests that the size-affected transformation stress is sensitive to the initial defect structure and that it can be tuned by a targeted introduction of dislocations. These findings demonstrate the high suitability of Ni-Mn-Ga as a robust shape-memory alloy in small-scale functional device engineering.
The use of high niobium alloyed cast iron alloys is a relatively new approach in which the niobium addition intends to improve the properties of the material by the precipitation of hard niobium carbides during solidification. Steels can be replaced by ductile cast iron in some rolling applications, such as gears and cams, in order to reduce material costs. The aim of this work is to evaluate ductile iron alloyed with 1 weight percent (wt.%) niobium for the as cast specimens and with 1.8 wt.% and 2.4 wt.% niobium for the austempered specimens under lubricated slip-rolling tests using mixed/boundary conditions in an Amsler-type machine. Austempered ductile iron (ADI) alloyed with 1 wt.% chromium, or Carbidic ADI, was tested for comparison. For the as cast conditions, the niobium addition resulted in an increase of wear resistance owing to the low contact pressure of these tests. However, for the austempered specimens, the best performance was found for unalloyed ADI. The main factor acting in the initiation and propagation of cracks in ductile iron is the presence of the graphite nodules. The coarse carbides also contributed to the initiation of cracks and spalling of the material.
The suitability of an Al2O3 coating for corrosion protection on X20Cr13 was evaluated in various artificial geothermal brines, focusing on the influence of different pH (4, 6 and 8) and their chemical compositions on the coating properties. All experiments were performed in the laboratory using autoclaves at 150 ◦C and 1 MPa in deaerated condition for 1 and 7 days. Results showed that the pH of geothermal waters is the most detrimental factor in the transformation of ɣ-Al2O3 and its protective abilities. Delaminations were found in the Coating exposed to geothermal brines with pH 4. FTIR spectra indicated a transformation of ɣ-Al2O3 to boehmite AlOOH after exposure to pH 4 and 6, and bayerite Al(OH)3 was formed after exposure to pH 8. Different Crystal structures of the hydrated Al2O3 also contribute to the stability of the coatings, observed by the SEM- EDX of the surface and cross-section of coatings. This study indicated that ɣ-Al2O3 sol-gel coating presents a promising aspect of corrosion protection in geothermal environment with a neutral pH.