Papers by Keyword: Hard Metals

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Authors: Uilame Umbelino Gomes, C. de Souza, Francisca de Fatima P. Medeiros, A.G.P. Silva, C. Ciaravino, M. Roubin
Authors: L. Merz, S. Rath, Volker Piotter, Robert Ruprecht, Jürgen Haußelt
Authors: Per Lennart Larsson, Erik Olsson
Abstract: In the present study contact between elastic-plastic dissimilar spherical particles are investigated. The investigation is based on analytical and numerical methods and in the latter case in particular the finite element method. The results presented are pertinent to force-displacement relations at contact when elastic and plastic deformations are of equal magnitude. Especially, hard metal particles are considered with a typical application area being analysis of powder compaction.
Authors: James Sears, Aaron Costello
Abstract: Most materials produced today are monolithic structures that are heat treated to perform a particular function. Laser Powder Deposition (LPD) is a technology capable of modifying a metallic structure by adding the appropriate material to perform a desired function (e.g., wear and corrosion resistance). LPD offers a unique fabrication technique that allows the use of soft (tough) materials as base structures. Through LPD a hard material can be applied to the base material with little thermal input (minimal dilution and heat-affected-zone {HAZ}), thus providing the function of a heat treatment or other surface modifications (e.g., carburizing, nitriding, thermal spray and electroplating). Several materials (e.g., Stellite 6 &21, 316 SS, 420 SS, M4, Rex 20, Rex 121, 10V, AeroMet 100, CCW+, IN 625 and IN 718) have been deposited on to carbon steel (4140, 4340, 1566, 1018) substrates to provide various functions for a number of industrial applications. These surface modifications have been evaluated through standard wear testing (ASTM G-65), surface hardness (Rc), micro-hardness (vickers), and optical microscopy. The results from these evaluations will be presented along with several industrial application case studies.
Authors: Jairo A. Escobar Gutiérrez, Márcio Celso Fredel, Paulo A.P. Wendhausen, Aloísio Nelmo Klein
Authors: Akhilesh Kumar Swarnakar, S. Giménez, Sedigheh Salehi, Jef Vleugels, Omer Van der Biest
Abstract: The Impulse Excitation Technique (IET) is a non-destructive technique for evaluation of the elastic and damping properties of materials. This technique is based on the mechanical excitation of a solid body by means of a light impact. For isotropic, homogeneous materials of simple geometry (prismatic or cylindrical bars), the resonant frequency of the free vibration provides information about the elastic properties of the materials. Moreover, the amplitude decay of the free vibration is related to the damping or internal friction of the material. At present, IET is a well-established non-destructive technique for the calculation of elastic moduli and internal friction in monolithic, isotropic materials. Standard procedures are described in ASTM E 1876-99 and DIN ENV 843-2. IET can also be performed at high temperature (HT-IET) using a dedicated experimental setup in a furnace and constitutes a valuable tool in the field of mechanical spectroscopy. In the present work, the most recent advances in high temperature characterization using IET at K.U. Leuven are presented: the deformation behaviour of WC-Co hard metals, softening phenomena in TiB2, relaxation mechanisms in ZrO2 composites and “in-situ” monitoring of the damage evolution in uniaxially pressed metallic green compacts during delubrication.
Authors: Nikoloz Jalabadze, Lili Nadaraia, Levan Khundadze
Abstract: Due the rapid heating rate combined with high pressure by the Spark Plasma Sintering (SPS) technologies possible manufacture a wide range of novel materials with exceptional properties that cannot be achieved using conventional sintering techniques. Hard metals are, from a technical point of view, one of the most successful composite materials. An overview of the metallurgical reactions during the SPS sintering process of powder mixtures for the manufacture of hard metals is presented. The relatively complex phase reactions in the multi-component system TiC-Mo-W-Ni are discussed. There were elaborated a new technology for the fabrication of nanocrystalline hard metals of a new class assigned for the production of articles with high different characteristics. Elaborated materials are characterized by high melting temperature, hardness, wear-resistance, and satisfactory strength at high temperature and corrosive resistance. Through the use of developed technology and the appropriate structural condition gives possibility to achieve high physical-mechanical characteristics. Obtaining of composite materials via elaborated technology is available from the corresponding complex compounds and directly consisting elements too. In this case High-temperature Self-propagation Synthesis (SHS) and spark plasma sintering/synthesis (SPS) process are united and during a single operation it is possible to get not only the powder materials but at the same time obtain required details.
Authors: Cristina M. Fernandes, Ana Maria R. Senos, M. Teresa Vieira
Authors: Fernando A. Costa Oliveira, Bernard Granier, J.M. Badie, Jorge Cruz Fernandes, Luís Guerra Rosa, Nobumitsu Shohoji
Abstract: Synthesis of single-phase tungsten sub-carbide W2C was attempted by heating pellets made out of a source of carbon (graphite-G) and W powders with G/W atom ratio between 0.35 and 0.50 to two target temperatures, namely 1600°C and 1900°C in an argon atmosphere using a solar furnace at PROMES-CNRS in Odeillo (France). The results showed that synthesis of single-phase W2C phase was difficult at either target temperature yielding the W2C co-existed with free metallic W. It was noted that the thin top surface layer of the solar-synthesised tungsten carbide pellets heated to 1900°C was distinguishable from the rest of the bulk specimen showing localised growth of nano-meter scale WC whiskers over W2C grains. Detailed XRD (X-ray diffraction) results on the effect of both G/W ratio and temperature on W2C lattice parameters are discussed.
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