Improvement of the wear behaviour of highly-loaded components and tools by multi-combined surface treatment

This paper introduces a novel multi-combined surface treatment consisting of the individual treatments of plasma nitriding (PN), physical vapour deposition (PVD) and electron beam hardening (EBH). Using graded surface layers produced by such a combined surface treatment, it is possible to withstand the complex load conditions incurred by components and tools. It is shown, that the treatment sequences PN+EBH+PVD and EBH+PN+PVD are suitable for improving material properties. These multi-combined surface treatments lead to a significant improvement in load-supporting capacity. Critical load values of cohesive failure measured by scratch tests are tripled when compared to the individual treatment of PVD, and increased by at least 20% in comparison to the duplex treatments of EBH+PVD or PN+PVD. The metallurgical compatibility of the single treatments is essential for the success of combined treatments. Material-specific limitations are defined, which exclude failure due to crack initiation, the occurrence of retained austenite, and tempering effects. Based on the model wear-test assembly block-on-cylinder, it was proved, that the specific wear rate of multi-combined treated specimens is reduced about 20-50% while wear of counterpart components is decreased as well. The triplex surface heat treatment introduced opens up new prospects for highly-loaded components and tools

Improvement of the wear behaviour of highly-loaded components and tools by multi-combined surface treatment

This paper introduces a novel multi-combined surface treatment consisting of the individual treatments of plasma nitriding (PN), physical vapour deposition (PVD) and electron beam hardening (EBH). Using graded surface layers produced by such a combined surface treatment, it is possible to withstand the complex load conditions incurred by components and tools. It is shown, that the treatment sequences PN+EBH+PVD and EBH+PN+PVD are suitable for improving material properties. These multi-combined surface treatments lead to a significant improvement in load-supporting capacity. Critical load values of cohesive failure measured by scratch tests are tripled when compared to the individual treatment of PVD, and increased by at least 20% in comparison to the duplex treatments of EBH+PVD or PN+PVD. The metallurgical compatibility of the single treatments is essential for the success of combined treatments. Material-specific limitations are defined, which exclude failure due to crack initiation, the occurrence of retained austenite, and tempering effects. Based on the model wear-test assembly block-on-cylinder, it was proved, that the specific wear rate of multi-combined treated specimens is reduced about 20-50% while wear of counterpart components is decreased as well. The triplex surface heat treatment introduced opens up new prospects for highly-loaded components and tools

Leitfaden zur Bildverarbeitung in der zerstörungsfreien Prüfung

Der Fraunhofer Vision »Leitfaden zur zerstörungsfreien Prüfung mit Bildverarbeitung« (Band 18) gibt einen praxisorientierten Überblick über bildgebende Verfahren, die in der zerstörungsfreien Prüfung zum Einsatz kommen. Nach einem einführenden Überblick zur »Bildverarbeitung in der ZfP« werden ausgewählte Methoden ausführlich vorgestellt. Das Spektrum reicht dabei von »klassischen« Verfahren, wie Röntgen, Wärmefluss-Thermographie, Ultraschall, Terahertz-Messtechnik oder Wirbelstrom über neuere Verfahren wie Magnetresonanz, Magnetfeldbildgebung oder optische Kohärenztomographie hin zu Verfahren wie Ellipsometrie, Polarisation oder Hyperspectral Imaging. Beschrieben werden jeweils physikalische Grundlagen, Aufnahme- und Sensortechniken sowie Aspekte der Bild- und Signalverarbeitung. Daneben erhält der Leser anhand von Beispielapplikationen Hinweise für die praktische Einsatzfähigkeit der Prüfmethoden. Zur schnellen ersten Orientierung wird am Ende des Bands eine Übersicht angeboten, die wesentliche Technologien in tabellarischer Form auflistet und sie hinsichtlich ihrer typischen Einsatzgebiete und Anwendungsfelder sowie ihrer Vorteile und Einschränkungen kurz beschreibt

New results on light nuclei, hyperons and hypernuclei from HADES (HADES collaboration)

International audienceIn March 2019 the HADES experiment recorded 14 billion Ag+Ag collisions at √sNN = 2.55 GeV as a part of the FAIR phase-0 physics program. In this contribution, we present and investigate our capabilities to reconstruct and analyze weakly decaying strange hadrons and hypernuclei emerging from these collisions. The focus is put on measuring the mean lifetimes of these particles

Probing dense baryon-rich matter with virtual photons

International audienceAbout 10 μs after the Big Bang, the universe was filled—in addition to photons and leptons—with strong-interaction matter consisting of quarks and gluons, which transitioned to hadrons at temperatures close to kT = 150 MeV and densities several times higher than those found in nuclei. This quantum chromodynamics (QCD) matter can be created in the laboratory as a transient state by colliding heavy ions at relativistic energies. The different phases in which QCD matter may exist depend for example on temperature, pressure or baryochemical potential, and can be probed by studying the emission of electromagnetic radiation. Electron–positron pairs emerge from the decay of virtual photons, which immediately decouple from the strong interaction, and thus provide information about the properties of QCD matter at various stages. Here, we report the observation of virtual photon emission from baryon-rich QCD matter. The spectral distribution of the electron–positron pairs is nearly exponential, providing evidence for a source of temperature in excess of 70 MeV with constituents whose properties have been modified, thus reflecting peculiarities of strong-interaction QCD matter. Its bulk properties are similar to the dense matter formed in the final state of a neutron star merger, as apparent from recent multimessenger observation