5 Werkstofftechnik
Filtern
Dokumenttyp
- Vortrag (482)
- Zeitschriftenartikel (427)
- Posterpräsentation (118)
- Beitrag zu einem Tagungsband (77)
- Forschungsdatensatz (27)
- Buchkapitel (11)
- Dissertation (10)
- Forschungsbericht (7)
- Sonstiges (5)
- Sammelband (Herausgeberschaft für den kompletten Band) (3)
Sprache
- Englisch (1001)
- Deutsch (160)
- Mehrsprachig (9)
- Französisch (2)
- Russisch (1)
Schlagworte
- Additive Manufacturing (69)
- Additive manufacturing (66)
- Corrosion (57)
- Microstructure (45)
- Glass (42)
- Ontology (40)
- Creep (39)
- Transmission electron microscopy (31)
- Fatigue (30)
- EBSD (28)
Organisationseinheit der BAM
- 5 Werkstofftechnik (1173)
- 5.1 Mikrostruktur Design und Degradation (341)
- 5.2 Metallische Hochtemperaturwerkstoffe (286)
- 5.4 Multimateriale Fertigungsprozesse (222)
- 5.6 Glas (156)
- 5.3 Polymere Verbundwerkstoffe (133)
- 5.5 Materialmodellierung (119)
- 8 Zerstörungsfreie Prüfung (111)
- 9 Komponentensicherheit (100)
- 7 Bauwerkssicherheit (92)
- 5.0 Abteilungsleitung und andere (84)
- 8.5 Röntgenbildgebung (82)
- 6 Materialchemie (68)
- 7.6 Korrosion und Korrosionsschutz (45)
- 9.4 Integrität von Schweißverbindungen (39)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (31)
- 1 Analytische Chemie; Referenzmaterialien (28)
- 6.1 Oberflächen- und Dünnschichtanalyse (28)
- 9.6 Additive Fertigung metallischer Komponenten (27)
- 6.3 Strukturanalytik (26)
- 9.0 Abteilungsleitung und andere (23)
- 4 Material und Umwelt (21)
- 9.3 Schweißtechnische Fertigungsverfahren (19)
- 3 Gefahrgutumschließungen; Energiespeicher (18)
- 8.4 Akustische und elektromagnetische Verfahren (14)
- 6.6 Physik und chemische Analytik der Polymere (12)
- 8.0 Abteilungsleitung und andere (11)
- 4.2 Material-Mikrobiom Wechselwirkungen (10)
- 8.3 Thermografische Verfahren (9)
- 9.2 Versuchsanlagen und Prüftechnik (9)
- 1.2 Biophotonik (8)
- 3.1 Sicherheit von Gefahrgutverpackungen und Batterien (8)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (7)
- 7.4 Baustofftechnologie (7)
- 1.4 Prozessanalytik (6)
- 1.6 Anorganische Referenzmaterialien (6)
- 3.0 Abteilungsleitung und andere (6)
- 4.1 Biologische Materialschädigung und Referenzorganismen (6)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (6)
- 8.6 Faseroptische Sensorik (6)
- 6.2 Material- und Oberflächentechnologien (5)
- 6.7 Materialsynthese und Design (5)
- 7.7 Modellierung und Simulation (5)
- VP Vizepräsident (5)
- VP.1 eScience (5)
- 1.9 Chemische und optische Sensorik (4)
- 2 Prozess- und Anlagensicherheit (4)
- 2.1 Sicherheit von Energieträgern (4)
- 4.3 Schadstofftransfer und Umwelttechnologien (4)
- 6.0 Abteilungsleitung und andere (4)
- 6.4 Materialinformatik (4)
- 9.5 Tribologie und Verschleißschutz (4)
- 1.7 Organische Spuren- und Lebensmittelanalytik (3)
- 3.5 Sicherheit von Gasspeichern (3)
- 7.0 Abteilungsleitung und andere (3)
- 1.0 Abteilungsleitung und andere (2)
- 3.4 Sicherheit von Lagerbehältern (2)
- 4.0 Abteilungsleitung und andere (2)
- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (2)
- 7.1 Baustoffe (2)
- S Qualitätsinfrastruktur (2)
- 1.3 Instrumentelle Analytik (1)
- 1.8 Umweltanalytik (1)
- 2.0 Abteilungsleitung und andere (1)
- 3.6 Elektrochemische Energiematerialien (1)
- 7.2 Ingenieurbau (1)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (1)
- P Präsident (1)
- P.0 Präsident und andere (1)
- S.0 Abteilungsleitung und andere (1)
- S.1 Qualität im Prüfwesen (1)
Paper des Monats
- ja (11)
Transformers couple two sections of a circuit by electromagnetic induction. They are widely used to either transform alternating voltage levels or to transmit power or signals across galvanic isolation. Both of these functions are essential for the operation of sensors and controllers. Covering all aspects from idea to circuit performance and from design to manufacture, this paper presents the first comprehensive description of the making of miniaturized, rugged, up-to-100W transformers for embedding into multilayer circuit boards. For circular coils, the well-manageable Ampere-Laplace law is shown to yield reliable designs, predicting correctly the performance of manufactured hardware. This enables fast design without lengthy finite element modelling. In the low-power linear regime, basic relations describe how the device’s characteristics evolve from the material properties and device structure. While scattering Parameters are useful for the analysis of isolated transformers with their intrinsic parasitics, the interaction with the components of the final circuit and the aspects of power and efficiency are addressed by chain matrixes.
While these design rules are similar for multilayer boards of different material (like epoxy, Teflon, ceramics), the manufacturing of ceramic board transformers is considered here in detail. Low-temperature-cofired ceramic (LTCC) boards being sintered at 900 °C are particularly suited for harsh environments with chemical or thermal stress as frequently found at sensor positions. The transformer performance usually benefits from or even requires an integrated ceramic core of higher permeability, a ferrite, to shape the magnetic flux. Methods to sinter ferrites inside a dielectric ceramic multilayerandto measure their performance are therefore described in detail.Asthe sintering behaviour of dielectricandmagnetic ceramics differs considerably, their simultaneous sintering is challenging.However, the sintering temperatures of the usefulMnZnand NiZnCu ferrites can be lowered to that of the dielectric material with only moderate loss of permeability by glass additives. Furthermore, thermal mismatch between materials causes catastrophic failure or at least stress and loss of magnetic performance during cooling to room temperature after sintering. This is avoidable by either adjusting the thermal expansion coefficient of the ferrite or by enclosing the ferrite between stressreleasing separation layers.We present the state of the art in materials development according to the first approach as well as fully functional devices made with the second technique.
Other applications not directly addressed but well related to this work are characterized by low load resistance in relation to the coil resistance of the transformer. Efficient power transmission then requires that technological solutions are applied to achieve the lowest possible resistive loss inside the coils by an enlarged conductor cross-section.
As this is particularly challenging for LTCC boards, a technique is discussed to fabricate conductor traces with a thickness larger than their width.
This contribution provides current findings regarding materials susceptibility for CCUS applications. Basing on results gathered in 2 German long-term projects (COORAL and CLUSTER) suitable materials are introduced as well as dominating impurities of the CO2 stream and corrosion mechanisms. Investigations cover the whole CCUS process chain and provide the following recommendations for certain parts. Commercially available carbon steels are suitable for compression and pipelines as long as moisture content and impurities are limited (water 50 to 100 ppmv, SO2 and NO2 ca. 100 ppmv).
Corrosion rates increase with increasing water content (0.2 – 20 mm/a).
Condensation of acids and therefore droplet formation is always possible, even at low water contents.
A low SO2 content within the CO2-stream might be more important than a low water content.
Cr13-steels showed a general susceptibility to shallow pitting and pitting. So, they seem to be not suitable for CCUS applications.
Low alloyed steels showed better corrosion behavior (predictable uniform corrosion).
For direct contact with saline aquifer fluids only high alloyed steels shall be used.
Stable crack growth was measured for nominal dry and water-bearing (6 wt%) soda-lime silicate glasses in double cantilever beam geometry and combined with DMA studies on the effects of dissolved water on internal friction and glass transition, respectively. In vacuum, a decreased slope of logarithmic crack growth velocity versus stress intensity factor is evident for the hydrous glass in line with an increase of b-relaxation intensity indicating more energy Dissipation during fracture. Further, inert crack growth in hydrous glass is found to be divided into sections of different slope, which indicates different water related crack propagation mechanism. In ambient air, a largely extended region II is observed for the hydrous glass, which indicates that crack growth is more sensitive to ambient water.
Early Stage of Corrosion Formation on Pipeline Steel X70 Under Oxyfuel Atmosphere at Low Temperature
(2020)
The early stage of corrosion formation on X70 pipeline steel under oxyfuel atmosphere was investigated by applying a simulated gas mixture (CO2 containing 6700 ppmv O2, 100 ppmv NO2, 70 ppmv SO2 and 50 ppmv H2O) for 15 h at 278 K and ambient pressure. Short-term tests (6 h) revealed that the corrosion starts as local spots related to grinding marks progressing by time and moisture until a closed layer was formed. Acid droplets (pH 1.5), generated in the gas atmosphere, containing a mixture of H2SO4 and HNO3, were identified as corrosion starters. After 15 h of exposure, corrosion products were mainly X-ray amorphous and only partially crystalline. In-situ energy-dispersive X-ray diffraction (EDXRD) results showed that the crystalline fractions consist primarily of water-bearing iron sulfates. Applying Raman spectroscopy, water-bearing iron nitrates were detected as subordinated phases. Supplementary long-term tests exhibited a significant increase in the crystalline fraction and formation of additional water-bearing iron sulfates. All phases of the corrosion layer were intergrown in a nanocrystalline network. In addition, numerous globular structures have been detected above the corrosion layer, which were identified as hydrated iron sulphate and hematite. As a type of corrosion, shallow pit formation was identified, and the corrosion rate was about 0.1 mma−1. In addition to in-situ EDXRD, SEM/EDS, TEM, Raman spectroscopy and interferometry were used to chemically and microstructurally analyze the corrosion products.
On the influence of crystallography on creep of circular notched single crystal superalloy specimens
(2020)
The present work contributes to a better understanding of the effect of stress multiaxiality on the creep behavior of single crystal Ni-base superalloys. For this purpose we studied the creep deformation and rupture behavior of double notched miniature creep tensile specimens loaded in three crystallographic directions [100], [110] and [111] (creep conditions: 950 °C and 400 MPa net section stress). Crystal plasticity finite element method (CPFEM) was used to analyze the creep stress and strain distributions during creep. Double notched specimens have the advantage that when one notch fails, the other is still intact and allows to study a material state which is close to rupture. No notch root cracking was observed, while microstructural damage (pores and micro cracks) were frequently observed in the center of the notch root region. This is in agreement with the FEM results (high axial stress and high hydrostatic stress in the center of the notched specimen). Twinning was observed in the notch regions of [110] and [111] specimens, and <112> {111} twins were detected and analyzed using orientation imaging scanning electron microscopy. The present work shows that high lattice rotations can be detected in SXs after creep fracture, but they are associated with the high strains accumulated in the final rupture event.
A new race for high performance structural materials has started since the discovery of high entropy alloys at the beginning of the 21st century. The possible combination of several elements in an, until then, unknown composition space opened the ground for discovering new materials. Solid solution strengthening remains the most prominent mechanisms that is active in this family of materials, but it is supported by all other strengthening mechanism on the path to better and better performing materials. Chemical, thermal and mechanical approaches are combined to optimize these alloys. Optimum performances can be reached by using a high number of different strengthening mechanisms, induced both by composition and processing. The most prominent with composition induced mechanism is precipitation hardening, and on the processing side it is cold working such as cold-rolling, torsion or extrusion. The contribution uses tensile test data at room temperature solely for comparison – high temperature and cryogenic data are omitted because it would lead beyond the scope of this manuscript.
Materialprüfung
(2019)
Die Materialprüfung dient der Analyse der Eigenschaften, der Qualität und der Sicherheit vonMaterialien undWerkstoffen. Die häufigsten Verfahren umfassen die Analyse der chemischen Zusammensetzung und der Mikrostruktur sowie die Ermittlung von Werkstoffkennwerten. Dazu zählt auch die Bestimmung des Materialverhaltens unter verschiedenen Beanspruchungen bis hin zu komplexen Beanspruchungen. Die Verwendung von Referenzmaterialien, Referenzorganismen und Referenzverfahren dient der Zuverlässigkeit und Richtigkeit von Messungen, Prüfungen und Analysen.
Hydrocarbons fuel our economy. Furthermore, intermediate goods and consumer products are often hydrocarbon-based. Beside all the progress they made possible, hydrogen-containing substances can have severe detrimental effects on materials exposed to them. Hydrogen-assisted failure of iron alloys has been recognised more than a century ago. The present study aims to providing further insight into the degradation of the austenitic stainless steel AISI 304L (EN 1.4307) exposed to hydrogen. To this end, samples were electrochemically charged with the hydrogen isotope deuterium (2H, D) and analysed by scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). It was found that deuterium caused a phase transformation from the original γ austenite into ε- and α’-martensite. Despite their low solubility for hydrogen, viz. deuterium, the newly formed phases showed high deuterium concentration which was attributed to the increased density of traps. Information about the behaviour of deuterium in the material subjected to external mechanical load was gathered. A four-point-bending device was developed for this purpose. This allowed to analyse in-situ pre-charged samples in the ToF-SIMS during the application of external mechanical load. The results indicate a movement of deuterium towards the regions of highest stress.
Accelerator magnets that can reach magnetic fields well beyond the Nb-Ti performance limits are presently being built and developed, using Nb3Sn superconductors. This technology requires reaction heat treatment (RHT) of the magnet coils, during which Nb3Sn is formed from its ductile precursor materials (a “wind and react” approach). The Nb3Sn microstructure and microchemistry are strongly influenced by the conductor fabrication route, and by the Phase changes during RHT. By combining in situ differential scanning calorimetry, high Energy synchrotron x-ray diffraction, and micro-tomography experiments, we have acquired a unique data set that describes in great detail the phase and microstructure changes that take place during the processing of restacked rod process (RRP), powder-in-tube (PIT), and internal tin (IT) Nb3Sn wires. At temperatures below 450 ° the phase evolutions in the three wire types are similar, with respectively solid state interdiffusion of Cu and Sn, Cu6Sn5 formation, and Cu6Sn5 peritectic transformation. Distinct differences in phase evolutions in the wires are found when temperatures exceed 450 °C. The volume changes of the conductor during RHT are a difficulty in the production of Nb3Sn accelerator magnets. We compare the wire diameter changes measured in situ by dilatometry with the phase and void volume evolution of the three types of Nb3Sn wire. Unlike the Nb3Sn wire length changes, the wire diameter evolution is characteristic for each Nb3Sn wire type. The strongest volume increase, of about 5%, is observed in the RRP wire, where the main diameter increase occurs above 600 °C upon Nb3Sn formation.