176,537 research outputs found

    Structure and wear mechanisms of nano-structured TiAlCN/VCN multilayer coatings

    Get PDF
    Dry sliding wear of transition metal nitride coatings usually results in a dense and strongly adhered tribofilm on the worn surface. This paper presents detailed electron microscopy and Raman spectroscopy characterizations of the microstructure, a newly developed multilayer coating TiAlCN/VCN and its worn surface after pin-on-disc sliding wear against an alumina ball. The friction coefficient in a range of 0.38–0.6 was determined to be related to the environmental humidity, which resulted in a wear coefficient of the coating varying between 1017 and 1016 m3 N1 m1. TEM observation of worn surfaces showed that, when carbon was incorporated in the nitride coating, the formation of dense tribofilm was inhibited

    Transmission electron microscopy and energy dispersive X-ray spectroscopy on the worn surface of nano-structured TiAlN/VN multilayer coating

    Get PDF
    Nano-structured TiAIN/VN multilayer hard coatings grown by cathodic arc metal ion etching and unbalanced magnetron sputtering deposition have repeatedly shown low coefficients of friction and wear. In this paper, we employed the combined methods of cross-sectional ion beam milling sample preparation, conventional transmission electron microscopy, energy dispersive X-ray spectroscopy and quantitative spectrum analysis to give a comprehensive characterization of wear induced tribofilm, worn TiAIN/VN surface as well as wear debris. The major wear mechanism operating in the TiAIN/VN coating is the tribo-oxidation wear. A 20-50 nm thick tribofilm was observed on the TiAIN/VN worn surface, having inhomogeneous density, amorphous structure and multicomponent V-Al-Ti-O composition. Therefore the real sliding contact during the ball-on-disk test was a three-body sliding system including the tribofilm, in which the self-sintering and shearing deformation of the multicomponent oxide film played a significant role in determining the low friction coefficient. Owing to the low friction and high hardness, the TiAIN/VN worn surface retained good structural integrity without any crack, delamination or detectable deformation, resulting in minimized mechanical wear. (c) 2005 Elsevier B.V. All rights reserved

    Some Supplementaries to The Counting Semantics for Abstract Argumentation

    Full text link
    Dung's abstract argumentation framework consists of a set of interacting arguments and a series of semantics for evaluating them. Those semantics partition the powerset of the set of arguments into two classes: extensions and non-extensions. In order to reason with a specific semantics, one needs to take a credulous or skeptical approach, i.e. an argument is eventually accepted, if it is accepted in one or all extensions, respectively. In our previous work \cite{ref-pu2015counting}, we have proposed a novel semantics, called \emph{counting semantics}, which allows for a more fine-grained assessment to arguments by counting the number of their respective attackers and defenders based on argument graph and argument game. In this paper, we continue our previous work by presenting some supplementaries about how to choose the damaging factor for the counting semantics, and what relationships with some existing approaches, such as Dung's classical semantics, generic gradual valuations. Lastly, an axiomatic perspective on the ranking semantics induced by our counting semantics are presented.Comment: 8 pages, 3 figures, ICTAI 201

    Nuclear dependence asymmetries in direct photon production

    Get PDF
    We study the nuclear dependences of high-pTp_T jet cross sections in one photon and one jet production in proton-nucleus collisions. We find that there exist asymmetries between the outgoing jets and photons. A convincing reason responsible for those asymmetries are demonstrated in perturbative QCD. Significant nuclear enhancements are also found in the inclusive jet cross sections.Comment: 9 pages, LaTeX, 5 ps-figure

    Why Use a Hamilton Approach in QCD?

    Full text link
    We discuss QCDQCD in the Hamiltonian frame work. We treat finite density QCDQCD in the strong coupling regime. We present a parton-model inspired regularisation scheme to treat the spectrum (θ\theta-angles) and distribution functions in QED1+1QED_{1+1}. We suggest a Monte Carlo method to construct low-dimensionasl effective Hamiltonians. Finally, we discuss improvement in Hamiltonian QCDQCD.Comment: Proceedings of Hadrons and Strings, invited talk given by H. Kr\"{o}ger; Text (LaTeX file), 3 Figures (ps file