5 Werkstofftechnik
Filtern
Erscheinungsjahr
- 2021 (168) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (71)
- Vortrag (71)
- Beitrag zu einem Tagungsband (11)
- Posterpräsentation (8)
- Dissertation (2)
- Sonstiges (2)
- Buchkapitel (1)
- Corrigendum (1)
- Forschungsdatensatz (1)
Schlagworte
- Corrosion (19)
- Additive manufacturing (10)
- Additive Manufacturing (8)
- Steel (8)
- EBSD (7)
- CCS (6)
- Microstructure (6)
- Fatigue (5)
- Mechanical properties (5)
- Residual stress (5)
- SEM (5)
- Carbon capture storage (4)
- Crack growth (4)
- Creep (4)
- Fraktographie (4)
- Geothermal (4)
- Laser powder bed fusion (4)
- Ontology (4)
- Sintering (4)
- Thermomechanical fatigue (4)
- Transmission electron microscopy (4)
- 316L (3)
- CO2 quality (3)
- Ceramics (3)
- Corrosion fatigue (3)
- Crack tip opening displacement (3)
- Creep behavior (3)
- Digitalisierung (3)
- Full Notch Creep Test (3)
- Glass fiber reinforced polymers (3)
- High alloyed steel (3)
- High-temperature corrosion (3)
- Impurities (3)
- Inverted classroom (3)
- Martensitic steel (3)
- Metallic glass (3)
- Microstrucrue Design (3)
- Oxidation (3)
- Pattern matching (3)
- Pipeline network (3)
- Recommendations (3)
- Thermoelectrics (3)
- Whole-chain CCS scenario (3)
- Wissensrepräsentation (3)
- Agglomerates (2)
- Aging (2)
- Al2O3 (2)
- Alkali ions (2)
- CALPHAD (2)
- CCU (2)
- CO2 (2)
- Carbon capture and storage (2)
- Characterization (2)
- Chemically complex alloy (2)
- Chromium oxide (2)
- Coatings (2)
- Composite (2)
- Crystal plasticity (2)
- Damage (2)
- Defects (2)
- Density-based Thermodynamics (2)
- Density-based model (2)
- Diffusion (2)
- Diopsid (2)
- Dispersion process (2)
- Electron diffraction (2)
- Environmental stress cracking (2)
- Fatigue performance (2)
- Fe-Al alloys (2)
- Fractography (2)
- Fracture surface (2)
- Fracture toughness (2)
- Glass (2)
- Glass forming (2)
- High entropy alloy (2)
- High entropy alloys (2)
- High-density polyethylene (2)
- High-entropy alloy (2)
- High-entropy alloys (2)
- Hydrogen (2)
- Intermetallics (2)
- Iron aluminides (2)
- Kikuchi diffraction (2)
- Manganese oxide (2)
- Microstructural analysis (2)
- Multilayertechnik (2)
- Nano-powder (2)
- Nanoindentation (2)
- Neutron diffraction (2)
- Nickel alloys (2)
- Nickel-base alloy (2)
- Nickel-base superalloys (2)
- Normung (2)
- Ontologie (2)
- Oxidation behavior (2)
- PMD (2)
- Phase-field simulation (2)
- Plasticity (2)
- Polyaniline (2)
- Protective coating (2)
- REM (2)
- Residual Stress (2)
- SIMS (2)
- Sample preparation (2)
- Semantic Web (2)
- Shear bands (2)
- SiO2 (2)
- Sibayak (2)
- Single-Crystal (2)
- Single-crystals (2)
- Sol-gel coating (2)
- Spectroscopy (2)
- Standardization (2)
- Superalloys (2)
- Tensile Test (2)
- Thermoelectric (2)
- Ti-6Al-4V (2)
- Transmission electron microscopy (TEM) (2)
- Viscosity (2)
- Wall thickness (2)
- Zugversuch (2)
- 3D REM (1)
- 3D etching (1)
- 3D printing (1)
- 3D-printing (1)
- 4-Dimensional scanning transmission (1)
- 9-12%Cr steel (1)
- AGIL (1)
- AISI 316L (1)
- AM (1)
- Additive Fertigung (1)
- Advanced high strength steels (1)
- Ageing (1)
- Al alloys (1)
- Al-Cu alloy (1)
- Alkali and alkaline earth silicate and borate glass (1)
- Alkali zinc borate glass (1)
- Analytical scanning electron microscopy (1)
- Analytical services (1)
- Anisotropy (1)
- Aquifer fluid (1)
- Atomistic simulations (1)
- Austenite-to-martensite phase transformation (1)
- Behmite (1)
- Binder Jetting (1)
- Bio-ceramic engineering (1)
- Bioactive glass (1)
- Blended learning (1)
- Borate glasses (1)
- Brittle fracture (1)
- Bruchflächen (1)
- Bruchflächenauswertung (1)
- Bulk metallic glasses (1)
- Bundesoberbehörden (1)
- Burst test (1)
- CO2-storage (1)
- Cabon capture and storage (1)
- Calculated intrinsic fracture toughness (1)
- Carbon dioxide (1)
- Carbon fibres (1)
- Carbon steel (1)
- Casing (1)
- Catalogue of services (1)
- Cellular substructure (1)
- Cement (1)
- Centrifugal casting (1)
- Ceramic (1)
- Ceramic multilayer (1)
- Ceramics 3D printing (1)
- Chemo-mechanical coupling (1)
- Coating (1)
- Complex borides (1)
- Composite pressure vessels (1)
- Composite recycling (1)
- Compositionally complex alloy (1)
- Compositionally complex alloys (1)
- Computed tomography (1)
- Contact mechanics (1)
- Contamination (1)
- Cooling simulations (1)
- Covid-19 (1)
- Cow stress (1)
- Cr2O3 (1)
- Crack growth in air (1)
- Crystal Defects (1)
- Crystallization (1)
- DCB (1)
- Damage Tolerance (1)
- Damage mechanisms (1)
- Datenbank (1)
- Datenmanagement (1)
- Deep learning (1)
- Defects engineering (1)
- Defects phase diagram (1)
- Defects thermodynamics (1)
- Deformation mechanisms (1)
- Densty-based Thermodynamics (1)
- Dental (1)
- Deposition microstructure (1)
- Die casting (1)
- Dielectric breakdown (1)
- Dielectric strength (1)
- Differential scanning calorimetry (DSC) (1)
- Diffraction (1)
- Digitization (1)
- Dislocation avalanches (1)
- Dislocation substructure (1)
- Diversity (1)
- Dry preparation (1)
- Drywood termite (1)
- EC4SafeNano (1)
- EDXRD (1)
- Elastic constants (1)
- Elastic energy (1)
- Elasticity (1)
- Electric field strength (1)
- Electrical insulators (1)
- Electron backscatter diffraction (1)
- Electron microscopy (1)
- Electron microscopy, transmission (1)
- Energy harvesting (1)
- Environmental Stress Cracking (1)
- Environmental stress cracking (ESC) (1)
- Ermüdung (1)
- Ermüdungsriss (1)
- European Centre (1)
- Eutectic (1)
- Failure mechanisms (1)
- Faser (1)
- Faser-Kunststoff-Verbund (1)
- Faser-Kunststoff-Verbunde (1)
- Fem (1)
- Ferritic Alloys (1)
- Fertigungsprozess (1)
- Fiber (1)
- Fibre/matrix bond (1)
- Fibre/matrix bonding (1)
- Finite element analysis (1)
- First year students (1)
- Flipped classroom (1)
- Flowability (1)
- Foaming (1)
- Focussed ion beam growth (1)
- Fracture (1)
- Fracture behavior (1)
- Fracture surfaces (1)
- Full notch creep test (FNCT) (1)
- Fullerite (1)
- Fungi (1)
- GFK (1)
- Gas storage (1)
- Gitterkonstanten (1)
- Glas (1)
- Glas fibre reinforced polymer (1)
- Glasmatrixkomposit (1)
- Glass Ceramic (1)
- Glass ceramic (1)
- Glass fiber reinforced polymer (1)
- Glass fibre (1)
- Glass fibre reinforced plastics (1)
- Glass powder (1)
- Glass structure (1)
- Glass-ceramics (1)
- Grain Boundary Phase Diagram (1)
- Grain boundary phase diagram (1)
- Grain boundary thermodynamics (1)
- HEA (1)
- HIP (1)
- HV-Insulation (1)
- Hard machining (1)
- Hardness (1)
- Heat accumulation (1)
- Heat treatment (1)
- Hertzian cracks (1)
- High Cycle Fatigue (1)
- High Temperature Corrosion (1)
- High alloyed steels (1)
- High entropy superalloys (1)
- High temperature (1)
- High temperature corrosion (1)
- High-Temperature Corrosion (1)
- Hochentropie-Legierung (1)
- Hochtemperaturbrennstoffzelle (1)
- Homogenization (1)
- Hot pressing (1)
- In-situ (1)
- In-situ process monitoring (1)
- Inter layer time (1)
- Interface (1)
- Interfacial Spinodal (1)
- Interfacial anisotropy (1)
- Interfacial free energy (1)
- Interfacial shear strength (1)
- Intermetallic (1)
- Investment casting (1)
- Ion beam erosion Sectioning (1)
- Iron (1)
- Iron oxide nanoparticles (1)
- Keramik (1)
- Kikuchi patterns (1)
- Knowledge Graphs (1)
- Korrosion (1)
- L-PBF (1)
- Laser beam melting (LBM) (1)
- Laser scanning microscopy (LSM) (1)
- Lattice parameters (1)
- Lattice structures (1)
- Layering misalignment (1)
- Layerwise Slurry Deposition (1)
- Lecture films (1)
- Lecture videos (1)
- Legierung mit komplexer Zusammensetzung (1)
- Lehrfilm (1)
- Lehrfilmformate (1)
- Liquid metal embrittlement (1)
- Lithography-based technologies (1)
- Long-term aging (1)
- Low Cycle Fatigue (1)
- Low strain (1)
- Lösungsmittel (1)
- MEA (1)
- Machine Learning (1)
- Martensite (1)
- Martensitic steels (1)
- Martensitic structure (1)
- Martensitic transformation (1)
- Materialmodell (1)
- Matrix (1)
- Mechanical anisotropy (1)
- Metallic glasses (1)
- Metallic silver precipitates (1)
- Microbiologically influenced corrosion (1)
- Micromanipulation (1)
- Microstructural orientation (1)
- Microstructure and texture (1)
- Milling (1)
- Misfitting precipitate (1)
- Missing acknowledgment (1)
- Molecular dynamics (1)
- Molten salt (1)
- Monte-Carlo-Analysis (1)
- Multilayer (1)
- Multilayers (1)
- Nano (1)
- Nano metal fluorides (1)
- Nano-composite (1)
- Nano-landscape (1)
- Nano-safety (1)
- Nanocrystalline alloys (1)
- Nanocrystalline structure (1)
- Nanomaterial (1)
- Nanomaterials (1)
- Nanoparticles (1)
- Nanopartikel (1)
- Net zero (1)
- Neutron Diffraction (1)
- Nickel-based superalloys (1)
- Nimonic 75 (1)
- Non-desired foaming (1)
- Oberflächenaktive wässrige Medien (1)
- Online (1)
- Online teaching (1)
- Ontologien (1)
- Ontology development (1)
- Optic (1)
- Optical criterion of brittleness (1)
- Orientation-dependent microstructure (1)
- Ostwald ripening (1)
- Oxides (1)
- Parametric modeling (1)
- Particle size (1)
- Phase field model (1)
- Phase separation (1)
- Phasenidentifikation (1)
- Pipeline (1)
- Pitting (1)
- Plasma nanocoatings (1)
- Platform Material Digital (1)
- Platform Material Digital (PMD) (1)
- Platform MaterialDigital (1)
- Plattform Material Digital (PMD) (1)
- Pole figures (1)
- Polyethylen hoher Dichte (1)
- Polyethylene (1)
- Polymer Matrix Composites (1)
- Polymer composite (1)
- Polymer-Ceramic-Composite (1)
- Polymer-ceramic mixtures (1)
- Porosity (1)
- Porous materials (1)
- Portfolio (1)
- Positron annihilation spectroscopy (1)
- Powder bed additive manufacturing (1)
- Powder bed density (1)
- Powder flow (1)
- Powder rheology (1)
- Powder-based processes (1)
- Power law (1)
- Precipitate shape (1)
- Precipitation (1)
- Preparation (1)
- Pressure assisted sintering (1)
- Principal stress components (1)
- Projekt AGIL - Alterung additiv gefertigter metallischer Materialien und Komponenten (1)
- Properties (1)
- Pull-out (1)
- Radon transform (1)
- Real-time deformation (1)
- Recycling (1)
- Reference data (1)
- Reference material (1)
- Reference material BCR-425 (1)
- Refractory chemically complex alloys (1)
- Residual strains (1)
- Residual stresses (1)
- Review (1)
- Rissheilung (1)
- S-phase (1)
- SEM micrography (1)
- SHM (1)
- Salzschmelzen (1)
- Sample holder (1)
- Scan strategies (1)
- Scarf joint (1)
- Scarf joint repair (1)
- Scarf repairs (1)
- Schadensanalyse (1)
- Schlickerdeposition (1)
- Schwingstreifen (1)
- Schädigung (1)
- Screen printing (1)
- Selective laser melting (SLM) (1)
- Self-organization (1)
- Semantisches Web (1)
- Sensorik (1)
- Shape memory alloy (1)
- Shape-memory alloys (1)
- Shear strain (1)
- Shear-band structure (1)
- Short-beam strength (1)
- Silicate glass (1)
- Silver diffusion (1)
- Silver-glass-metallization-paste (1)
- Sintering atmosphere (1)
- Size effect (1)
- Small angle x-ray scattering (1)
- Small-scale (1)
- Solid solution strengthening (1)
- Solidification (1)
- Solubility (1)
- Spinodal Decomposition (1)
- Spinodal decomposition (1)
- Spring constant (1)
- Standard (1)
- Standardisierung (1)
- Strain rate dependence (1)
- Stress intensity (1)
- Stress-corrosion (1)
- Sulfidation (1)
- Sulphidation (1)
- Supercritical CO2 (1)
- Superlegierung (1)
- Surface energy (1)
- Symbolik (1)
- Symmetric dwell periods (1)
- Synchrotron radiation (1)
- Synchrotron radiations (1)
- Technical Ceramics (1)
- Temperature (1)
- Tensile test (1)
- Termites (1)
- Tetragonal distortion (1)
- Thermal Cycling (1)
- Thermal expansion (1)
- Thermal stress (1)
- Thermo mechanical fatigue (1)
- Thermo-mechanical-loading (1)
- Thermo-mechanics (1)
- Thermoelektrischer Generator (1)
- Thermography (1)
- Thermomechanics (1)
- Thermomechanik (1)
- Thermoplastic matrix (1)
- Thermosetting resin (1)
- Thin films (1)
- Three-dimensional tomographies (1)
- Topographie (1)
- Transmission Kikuchi diffraction (1)
- Transmission electron microscope (TEM) (1)
- Triply Periodical Minimal Surface (1)
- Two-photon adsorption (1)
- Umgebungsbedingter Spannungsriss (1)
- Welding (1)
- Wind turbine blade shell structures (1)
- Wood protection (1)
- Work of adhesion (1)
- Wärmespeicher (1)
- X-ray tomographic (1)
- X-ray-diffraction (1)
- XRD (1)
- Young´s Modulus (1)
- Zirconia (1)
- Zyklische R-Kurve (1)
- electron microscopy (1)
- thermomechanische Beanspruchung (1)
- γ- и γ'-фазы, период кристаллической решетки (1)
- γ″ phase (1)
- θ′ phase (1)
- θ′-(Al2Cu) precipitate phase (1)
- высокие температуры (1)
- жаропрочные нике- левые сплавы (1)
- монокристалл (1)
- рентгеноструктурный анализ (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (168)
- 5.1 Mikrostruktur Design und Degradation (64)
- 5.2 Metallische Hochtemperaturwerkstoffe (39)
- 5.4 Multimateriale Fertigungsprozesse (28)
- 5.5 Materialmodellierung (23)
- 7 Bauwerkssicherheit (18)
- 5.0 Abteilungsleitung und andere (17)
- 5.3 Polymere Verbundwerkstoffe (17)
- 8 Zerstörungsfreie Prüfung (15)
- 5.6 Glas (14)
Eingeladener Vortrag
- nein (71)
Diese Untersuchung beschäftigt sich mit der Charakterisierung von Kurzrisswachstum in mittels Laser-Pulverbett-Verschmelzen (LPBF - Laser Powder Bed Fusion) hergestelltem rostfreien austenitischen Stahl. Spezifischer wird die Ermittlung zyklischer R-Kurven untersucht. Diese beschreiben den Aufbau des Widerstands gegen Ermüdungsrisswachstum - d.h. des Schwellenwertes - aufgrund von Rissschließeffekten bei physikalisch kurzen Rissen. Mit Hilfe der zyklischen R-Kurven kann die Fähigkeit eines Bauteils, physikalisch kurze Risse zu arretieren, charakterisiert werden. Wir verfügen damit über eine Schnittstelle zwischen klassischer Ermüdung und Bruchmechanik. Das ist gerade auch für additiv gefertigte (AM – Additive Manufacturing) Materialien von Interesse. Diese weisen prozessintrinsische Defekte auf, die als Initiierungsstellen kurzer Ermüdungsrisse agieren. Im Rahmen der experimentellen Untersuchungen wurden zyklische R-Kurven für konventionellen und LPBF AISI-316L-Stahl ermittelt. Insbesondere wurde der Einfluss verschiedener Wärmebehandlungen (WB1: 450°C, WB2: 800°C und WB3: 900°C) auf das Wachstumsverhalten physikalisch kurzer Risse im LPBF-Material untersucht. Aufgrund hoher Eigenspannungen war die Ermittlung des Kurzrisswachstumsverhaltens bei WB1 nicht möglich. Für WB2 und WB3 ergaben sich sehr unterschiedliche zyklische R-Kurven. Untersuchungen der Eigenspannungen, der Bruchfläche (insbesondere der Rauheit) und der Mikrostruktur sollen die Ursachen für das unterschiedliche Verhalten erklären. Die Ergebnisse werden mit den Verhältnissen in konventionellem Material verglichen.
Additive manufacturing (AM) processes allow a high level of freedom in designing and producing components for complex structures. They offer the possibility of a significant reduction of the process chain. However, the large number of process parameters influence the structure and the behavior of AM parts. A thorough understanding of the interdependent mechanisms is necessary for the reliable design and production of safe AM parts.
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.
Latente Wärmspeicher auf der Basis von NaCl-KCl-MgCl2 Mischungen stellen eine kostengünstige Option für die Energiespeicherung von Prozesswärme dar. Der Beitrag gibt einen Überblick über die materialwissenschaftlichen Herausforderungen im System Salz-Legierung, welche gelöst werden müssen, um diese Speichertechnologie industriell zu etablieren.
Phase diagrams are the roadmaps for designing bulk phases. Similar to bulk, grain boundaries can possess various phases, but their phase diagrams remain largely unknown. Using a recently introduced density-based model, here we devise a strategy for computing multi-component grain boundary phase diagrams based on available bulk (CALPHAD) thermodynamic data. Fe-Mn-Cr, Fe-Mn-Ni, Fe-Mn-Co, Fe-Cr-Ni and Fe-Cr-Co alloy systems, as important ternary bases for several trending steels and high-entropy alloys, are studied. We found that despite its solute segregation enrichment, a grain boundary can have lower solubility limit than its corresponding bulk, promoting an interfacial chemical decomposition upon solute segregation. This is revealed here for the Fe-Mn-base alloy systems. The origins of this counter-intuitive feature are traced back to two effects, i.e., the magnetic ordering effect and the low cohesive energy of Mn solute element. Different aspects of interfacial phase stability and GB co-segregation in ternary alloys are investigated as well. We show that the concentration gradient energy contributions reduce segregation level but increase grain boundary solubility limit, stabilizing the GB against a chemical decomposition. Density-based grain boundary phase diagrams offer guidelines for systematic investigation of interfacial phase changes with applications to microstructure defects engineering.
High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer Matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF).
Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated.
Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m−2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load.
The high-temperature corrosion behavior of the medium-entropy alloy Cr33Co33Ni33 (MEA) and the high-entropy alloy Fe20Cr20Co20Ni20Mn20 (HEA) in a mixed gas atmosphere of 10% H2O-2% O2 -0.5% SO2 + Ar as carrier gas [Vol.%] at 800 °C with duration times of t = 24h, 48h and 96h was investigated. Both alloys have a single-phase fcc microstructure. The oxidation kinetics of the HEA-CrMnFeCoNi roughly followed a linear rate law and a slow oxide growth was observable for the MEA-CrCoNi. The scale thickness of the corrosion layer in the quinary alloy increased with exposure time, while the scale thickness in the ternary alloy remained constant at around 1 µm. The MEA-CrCoNi developed a protective Cr2O3 layer with minor buckled parts. Co,Ni-chromite (Co,Ni)Cr2O4 was detected by XRD in minor amounts. The scale on HEA-CrMnFeCoNi displayed a triplex structure of a thin, continuous, inner Cr2O3 layer, a dense, intermediate Mn3O4 layer, and a thick, outer, porous layer consisting of Mn3O4 and MnSO4. Sulphides were only identified in the matrix of HEA-CrMnFeCoNi. Thermodynamic equilibrium calculations with FactSage (Log(S2) vs. Log(O2), ΔG of reactions) are in good agreement with these observations. The intense diffusion of Cr in the ternary alloy leads to an immediate formation of a protective Cr2O3 layer. The fast diffusion of Mn through the bulk HEA material and through the formed Cr2O3 layer compared to the other alloying elements is considered as the rate-limiting process.
Frass (fine powdery refuse or fragile perforated wood produced by the activity of boring insects) of larvae of the European house borer (EHB) and of drywood termites was tested as a natural and novel feedstock for 3D-printing of wood-based materials. Small particles produced by the drywood termite Incisitermes marginipennis and the EHB Hylotrupes bajulus during feeding in construction timber, were used. Frass is a powdery material of particularly consistent quality that is essentially biologically processed wood mixed with debris of wood and faeces. The filigree-like particles flow easily permitting the build-up of woodbased structures in a layer wise fashion using the Binder Jetting printing process. The Quality of powders produced by different insect species was compared along with the processing steps and properties of the printed parts. Drywood termite frass with a Hausner Ratio HR = 1.1 with ρBulk = 0.67 g/cm3 and ρTap = 0.74 g/cm3 was perfectly suited to deposition of uniformly packed layers in 3D printing. We suggest that a variety of naturally available feedstocks could be used in environmentally responsible approaches to scientific material sciences/additive manufacturing.
Kirkendall porosity that forms during interdiffusion in a diffusion couple of nickel-base superalloy CMSX-10 with pure nickel is investigated. The diffusion experiments are conducted at a temperature of 1250 °C, where the strengthening ƴ'-phase ist partially dissolved. The porosity is studied by X-ray sub-μ tomography with a spatial resolution of about 0.35³ μm³ at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. It is found that depending on the distance from the interface the Kirkendall pores take different shapes: octahedral, rounded pyramidal, drop shaped, dendritic, pear shaped, and joint shapes. Such a variety of pore morphologies indicates a complex multistage process of porosity nucleation and growth under vacancy supersaturation of different degrees. The experimental findings are interpreted on the basis of the results of diffusion modeling. It is shown that the kinetics of porosity growth is essentially influenced by the dissolution of the ƴ'-phase.
Ceramic springs combine attractive properties for applications in machinery, metrology, and sensor technology. They are electrically insulating, non-magnetic, provide a linear stress-strain behavior, and are stable at high temperatures and in corrosive environments. Generally, the precise dimensioning of a ceramic spring with respect to the spring constant is challenging. Different models are described, but many of these calculations do not match the actual spring properties. We demonstrate a reliable approach for the dimensioning and manufacturing of helical compression springs with a rectangular winding cross-section. Based on the German standard DIN 2090, which is referring to metallic springs, the spring constant can be calculated based on shear modulus, diameter, height, widths, and number of windings. Different ceramic springs were produced by milling of sintered hollow cylinders of zirconia, alumina and silicon nitride. The experimental spring constants are in very good agreement with the calculated values. Spring constants of zirconia springs were varied over three orders of magnitude between 0.02 N/mm and 5 N/mm by purposeful adaption of the spring geometry. The combination of dimensioning based on DIN 2090 and precise hard machining offers a reliable technology for the fabrication of tailored ceramic springs for special applications.