867 research outputs found
Se Nanopowder Conversion into Lubricious 2D Selenide Layers by Tribochemical Reactions (Adv. Mater. 42/2023)
No full textIn article number 2302076, Philipp G. Grützmacher, Manel Rodríguez Ripoll, Carsten Gachot, Ali Erdemir, Maria Clelia Righi, and co-workers demonstrate that when Se nanoparticles are sprinkled onto Mo or W metallic surfaces, friction comes down dramatically through the formation of transition metal dichalcogenides (TMDs) during sliding. Ab initio molecular dynamics simulations uncover the atomistic mechanisms responsible for the formation of these TMDs
BOOK OF ABSTRACTS of ECOTRIB 2019 7th European Conference on Tribology with the special event MaTri '19 4th Austria-India-Symposium on Materials Engineering and Tribology - Wien, Austria, 12-14 June 2019
No full textThe ECOTRIB congress pays special attention to economy and ecology (“ECO”) issues and possible answers that can be given by modern tribology science and technology. An explicit aim is, of course, to present R&D activities, both from academic and research institutions, as well from industry. The idea to install a regular Central and South European congress on tribology led to first formal preparations in 2005, the biennial conference cycle started 2007 in Ljubljana, Slovenia. Subsequently, the national tribology societies from Slovenia, Italy, Austria, and Switzerland formed the “ECOTRIB Consortium”.
A special event within ECOTRIB is the MaTri 2019. This conference is a collaboration between Austria and India with the topic on material research focussed on tribology applications, biannually organized in these two countries, brings together researchers form India and Europe.
The economic, social and political framework conditions have changed considerably over the last ten years, and it seems that these have also had a much stronger influence on the situation for research and technological progress than, conversely, research findings have been able to influence political and economical decisions. Thus, it is of great importance to repeatedly draw attention to the achievements of technical sciences, in particular of tribology. As tribologists we are aware to be able to make decisive contributions to answering urgent questions about energy problems, the design of sustainable products and the reliability and safety of technical devices and equipment. This will be even more effective the more we understand the specific micro- and nano-conditions and procedures of a tribocontact and how these “tribotopes” (term coined by AC2T for its peculiar research approach) interact with the macro conditions in a specific application.
It cannot be expected that tribology per se triggers hypes similar to those coined by the inflationary use of the catchwords nanotechnology, industry 4.0, graphene, digitalization or artificial intelligence. However, tribology – especially in the interpretation as the "generic science of friction and wear", again confirmed by P. JOST in 2016, – has a distinct application relevance, and it has always been understood as a science characterized by an interdisciplinary approach. It is therefore more than ever crucial to solve the respective tasks by incorporating relevant findings and methods from other fields of knowledge. And these tasks are currently characterized by a paradigm shift, especially in the field of mobility, energy conversion, and production processes. This automatically results in new challenges for tribology, but also in a wide variety of already existing and as well emerging working methods.
ECOTRIB 2019 offers a platform to present and discus actual research activities and results, which is important for the communication between scientist and engineers. Moreover, it is an excellent opportunity for the new generation of tribologist to become acquainted with the variety of tasks and approaches and have the chance to present their own research work
A Different Perspective on the Solid Lubrication Performance of Black Phosphorous: Friend or Foe?
Get PDFBlack phosphorous (BP), a promising 2D material with exceptional electronic andoptical properties, has shown remarkable potential in tribology as an additive inliquid lubrication and a composite in solid lubrication. However, its potential as thestandalone solid lubricant is still at its early stage. This study evaluates BP’s solidlubrication performance as deposited coating (by drop casting) on a variety ofmetallic substrates (polished AISI 52 100 steel, aluminum, copper, and iron) underdifferent contact pressures using a ball-on-disc linear-reciprocating test machine indry conditions. The results demonstrate that BP does not systematically reducefriction and wear. Depending on the contact pressure and the characteristic of thesubstrate material (particularly surface roughness), its friction and wear behaviorvary a great deal. The best results observed are a 33% reduction in friction withincreased surface roughness on iron and a 23% reduction in wear on aluminum.While no general trend is observed for contact pressure effects, increased substrateroughness proves beneficial, enhancing lubricant retention and exploiting BP’s lowinterlayer shear mechanism. Therefore, this study demonstrates that while promis-ing, BP’s solid lubrication performance is not exceptional. It also highlights theimportance of optimizing test conditions and materials for enhanced lubrication
Correction to: When terminology hinders research: the colloquialisms of transitions of control in automated driving (Cognition, Technology & Work, (2022), 10.1007/s10111-022-00705-3)
Get PDFIn the original article, author affiliation published with error. The correct affiliations are: Davide Maggi—Institute for Transport Studies, Leeds, UK. Richard Romano—Institute for Transport Studies, Leeds, UK. Oliver Carsten—Institute for Transport Studies, Leeds, UK. Joost C. F. De Winter—Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands. The original article has been corrected.Human-Robot Interactio
Transition metal carbo chalcogenides: A novel family of 2D solid lubricants
No full textTwo-dimensional (2D) layered materials such as transition metal dichalcogenides (e.g., MoS2, WS2) and MXenes (e.g., Ti3C2Tx), as well as hybrids of these materials are the focus of current research in solid lubrication due to their outstanding performance. Transition metal carbo-chalcogenides (TMCCs), consisting of an MXene core and a TMD-like surface, represent an inherent combination of TMDs and MXenes without the need to construct hybrids out of the individual layers. Due to their layered structure and surface chemistry, favorable tribological properties can be expected from these novel materials. Here, multilayer Ta2S2C and Nb2S2C TMCCs are deposited solely as a powder onto a steel substrate and their tribological properties under linear sliding against different counterbodies, i.e., Al2O3, SiC, 100Cr6, and polytetrafluoroethylene (PTFE) are discussed. Advanced materials characterization techniques are used to detect the presence of TMCCs inside the wear tracks and to reveal their 2D structure within the tribofilm. Finally, density functional theory (DFT) simulations are used to unravel the easy shearability of TMCCs at the nanoscale. The results demonstrate the great potential of this new 2D material family, which also offers many possibilities for defined tuning of the solid-solid interface
Mechanisms and Prediction of Abrasive Wear: Unveiling the Impact of Waviness and Oscillation
Get PDFAbrasiver Verschleiß ist ein kritischer Faktor für die Leistung wie auch die Lebensdauer von tribologischen Kontakten, wie sie in vielen technischen Anwendungsbereichen vorkommen. Grundlegendes Verständnis der komplexen Mechanismen des abrasiven Verschleißes ist essentiell, um die Lebensdauer von Maschinen zu verlängern und deren Energieverbrauch zu reduzieren. In dieser Dissertation wurde das tribologische Verhalten von Wälzlagerstählen (100Cr6, AISI 52100) in einem Stift-Scheibe-Tribometer mit Flächenkontakt untersucht. Um abrasiven Verschleiß zu induzieren, wurden den Experimenten Aufschlämmungen mit Al2O3-Partikeln unterschiedlicher Größen (5 und 13 µm) als Grenzflächenmedium hinzugefügt.
Die experimentellen Ergebnisse zeigen, dass ein geschwindigkeitsinduzierter hydrodynamischer Effekt auftritt. Dieser verändert das Reibverhalten bei den tribologischen Experimenten in welchen 5 µm große Al2O3-Partikel hinzugegeben wurde erheblich. Dieser Effekt ist weniger ausgeprägt bei der Zugabe von 13 µm großen Al2O3-Partikeln. Dieser geschwindigkeitsabhängige hydrodynamische Effekt kann zu einer Zunahme der Schmierfilmdicke um 14% und einer Abnahme der Reibung um etwa zwei Drittel führen, begleitet von einem Übergang von Zwei-Körper-Abrasion zu Drei-Körper-Abrasion und einer Änderung des Verschleißmechanismus von Mikroschneiden und -pflügen zu Oberflächenzerüttung.
Desweiteren wurde der Einfluss der, oft übergangenen, Faktoren wie die Scheibenwelligkeit und die Oszillation der Kontaktflächen (aufgrund der Neigung der Scheibe in der Befestigung) untersucht. Diese führen zu inkonsistenter Reibung und ungleichmäßigem Verschleiß, selbst wenn diese Faktoren minimiert und kontrolliert wurden. Die Ergebnisse erlauben zwei wichtige Erkenntnisse: (1) Selbst geringfügige Welligkeiten (2 µm Höhendifferenz entlang einer 132 mm langen Verschleißspur) können den Reibungskoeffizienten signifikant erhöhen (um bis zu 91%); (2) Bereiche mit einem Abfall in der Oszillation scheinen die höchesten Reibkoeffizienten hervorzurufen. Durch die Analyse wichtiger Merkmale der Scheibenwelligkeitsprofile und der Oszillation wurde der “Hochreibungs-Indikator” entwickelt. Dieser identifiziert die Sektoren der Verschleißspur, in denen die Reibung wahrscheinlich höher ist als in anderen Sektoren. Diese Dissertation gibt erste Richtlinien zur Anpassung der Oberflächenstruktur und der Oberflächenneigung, um die gewünschten tribologischen Eigenschaften zu erreichen
Primjena lasera za obradu površine
No full textWith a new and increasing technological demands come new solutions. This is how laser
treatment found its way into material processing. As a main field in material processing, laser
surface treatment is the main focus of this paper. As it involves laser, in the first, theoretical
part, laser, their principle of working, types and their characteristics alongside with laser light
and its physics are described. In the second part, basic categorization and description of laser
surface treatment is given. The third part involves one of the processes described more
thoroughly; laser cladding. It gives practical problems and examples regarding repairing
technology in aerospace industry and sets up ground for a possible future experiment. At the
end, tests, which are recommended to be utilized to check the results of the future experiment,
are slightly described.S novim i rastućim tehnološkim zahtjevima dolaze nova rješenja. Tako je laserska obrada
pronašla svoj put u obradi materijala. Kao glavno polje u laserskoj obradi materijala, glavna
tema ovog rada je laserska obrada površine. Kako ono uključuje laser, u prvom, teorijskom
dijelu, opisan je upravo laser, njegovo načelo rada, tipovi lasera te karakteristike vezane za
lasersko svjetlo i osnovnu fiziku iza nje. U drugom dijelu dana je osnovna kategorizacija i
opis postupaka laserske obrade površine. Treći dio je fokusiran na jedan od bitnijih postupaka
primijenjen u laserskoj obradi površine; lasersko oblaganje. Prikazani su praktični problemi i
primjeri vezani s tehnološkim remontom u svemirskoj industriji te su postavljeni temelji za
budući eksperiment. Na kraju se ukratko opisuju česta ispitivanja koja se mogu provesti kako
bi se pomno provjerili i zabilježili rezultati budućeg eksperiment
Theodor Storm's novelle ''Carsten Curator': An evaluation of the terms "Befreiungsdichtung" and "das Peinliche".
No full textThis thesis undertakes an analysis of two interrelated aspects of Theodor Storm's later prose writing. The Novelle Carsten Curator (1877) has been selected since this work constitutes the most significant example of both "Befreiungsdichtung" and "das Peinliche". A definition of "Befreiungsdichtung" - the artistic projection of personal experience as an act of 'self-liberation' - and the way this is revealed in a series of earlier works is the subject of the first chapter. The following three chapters offer a study of the genesis of Carsten Curator and show by an investigation into Storm's relationship with his eldest son (Chapter 2) the extent of the autobiographical content in the Novelle (Chapter 4) and Storm's awareness of its 'confessional' nature while writing it (Chapter 3). The second part of the thesis concerns itself with artistic problems which thereby arose for Storm. The creative process conditioned Storm's treatment of the thematic complex of heredity, alcoholism and paternal responsibility in Carsten Curator and brought with it a degree of realism which the author and his more sensitive critics found 'unpoetic' and thus 'offensive' (Chapter 5). This constitutes "das Peinliche", which Storm believed detracted from the 'tragic' nature of the central conflict. The following two chapters assess Carsten Curator in the light of Storm's theoretical definitions of "das Tragische" and draw the conclusion that the Novelle is a prime example of his mature tragic art. Chapter 8 discusses the implications of "das Peinliche" for a study of Storm's later Novellen (1877 - 1888), including the development of his realism, the effects of literary censorship on his later treatment of the central themes of Carsten Curator and his knowledge of Naturalist literature, showing the absence of any direct influence where these themes are concerned. The thesis concludes that Storm's continuing preoccupation with the themes of Carsten Curator after 1877 can be attributed only to their 'confessional' nature
Study of the influence of laser surface texturing on the tribological properties of hardmetal parts
Get PDFAusgangspunkt dieser Arbeit sind vorangegangene Untersuchungen zu oberflächenoptimierten Maschinenelementen, insbesondere laserstrukturierte Führungsleisten in Honwerkzeugen. Aufgrund der Tatsache, dass Führungsleisten aus besonders harten Werkstoffen bestehen, bietet die Lasertexturierung eine effiziente Möglichkeit spezifische Strukturen in der Oberfläche zu erzeugen, um die tribologische Performance der Führungsleisten zu verbessern. In dieser Arbeit werden die Auswirkungen von vier linienförmigen Lasertexturen auf Hartmetall-Oberflächen aus tribologischer Sicht untersucht. Geprüft werden parallellaufende Riefen und Kreuzschraffuren mit 90° und 45° zueinander. Die Texturen wurden durch Laserpulse im Pikosekundenbereich mit Hilfe der Direkten Laser-Interferenzstrukturierung (DLIP) erzeugt. Für die Versuche wird ein Schmierstoffprüfgerät nach Brugger so umgebaut, dass ein Linienkontakt zwischen dem WC-Co-Prüfling und dem rotierenden Ring aus Einsatzstahl (16MnCr5) besteht. Zusätzlich ist eine Messeinheit integriert, um die Reibung beim Gleitreibungsversuch aufzuzeichnen. Neben der Analyse des Reib- und Verschleißverhaltens wird im Zuge dieser Arbeit auch die Topografie der Strukturen vor und nach den Tests mit einem Laserscanning-Mikroskop vermessen und mit Rauheitsparametern beschrieben. Zusätzlich wird die Oberfläche mit Hilfe von Rasterelektronenmikroskopie, Raman-Spektroskopie und Röntgendiffraktometrie analysiert. Die aufgezeichneten Messergebnisse der einzelnen Versuche zeigen eine Regelmäßigkeit untereinander auf. Somit liefert der Versuchsstand Daten auf Basis derer man das Reibverhalten der Prüflinge bestimmen kann. In Bezug auf Reibung zeigt sich, dass die Textur mit parallellaufenden Linien und senkrecht dazu laufender Gleitrichtung einen geringeren Reibwert gegenüber der polierten Referenzoberfläche erreicht. Gleichzeitig werden die Spitzen dieser Textur stärker abgetragen. Demgegenüber steht die Textur mit Kreuzschraffur von 90°, die höhere Reibung aufzeigt, deren Höcker aber weniger stark verschlissen sind. Die chemischen Oberflächenanalysen zeigen, dass sich Eisenoxidpartikel des Grundkörpers am Rand der Kontaktzone in den Laserstrukturen ansammeln, kaum aber in der Kontaktzone.The starting point of this thesis is preliminary investigation about optimization of machine elements regarding their surfaces, in particular the laser-textured guiding stones for honing processes. Due to the fact, that guiding stones are made of hard materials, laser surface texturing offers an efficient way to implement specific textures on surface in order to improve their tribological performance.In this work, the influence of four different laser textures on cemented carbide surfaces will be investigated from a tribological point of view. The textures are parallel line patterns and two cross patterns with induced angle of 90° and 45°. The textures have been produced by direct laser interference patterning (DLIP), using picosecond laser pulses. For the tribotests, a Brugger tribometer is modified in order to conduct a line-contact between the guiding stone (WC-Co) and the rotating ring (16MnCr5). In addition, a measuring unit is implemented to obtain the frictional force. Besides the friction and wear behaviour, also the topography of the surfaces is measured. Furthermore, chemical analyses by using SEM, Raman spectroscopy, and XRD are carried out.The frictional results of the individual tests show consistent behaviour, indicating that the modified Brugger tribometer provides reliable data for further analyses. Regarding friction, the line patterns with perpendicular sliding show a lower friction coefficient compared to the polished references; however, the same textures suffer more from wear. The cross pattern 90 ° shows a higher coefficient of friction, but its texture experiences less wear than the line pattern. The chemical analyses show that iron oxide particles accumulated mainly at the boundary of the wear tracks
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