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Tungsten Carbide (tungsten + carbide)
Selected AbstractsProcess Cost Comparison for Conventional and Near-Net-Shape Cermet Fabrication,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Yuhong Xiong Tungsten carbide,cobalt (WC,Co) is a widely used cermet that is generally fabricated into bulk parts via conventional powder metallurgy (P/M) methods. Because this material (and other cermets) is very hard and wear resistant, diamond grinding is generally required to fabricate complex parts. As an alternative, studies have shown the Laser Engineering Net Shaping (LENS) process to be a technically feasible method, allowing for fabrication of near-net-shape parts. The economic trade-offs, however, have not been previously characterized. In this work, technical cost modeling (TCM) is applied to compare the costs of fabricating WC,Co parts with the P/M process to those of the LENS process. Cost drivers are identified and sensitivity analysis is conducted. Results reveal that the uncertainty in functional unit has a significant effect on relative process costs, and the cost is sensitive to order size only if less than ten parts are produced. It is concluded that the LENS process is economically preferable if part size is small or part shape is complex. The P/M process is more suitable to produce large parts in simple shapes. [source] Effect of dentine smear layer on the performance of self-etching adhesive systems: A micro-tensile bond strength studyJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2010Pisol Senawongse Abstract This study aimed to evaluate the effect of the smear layer on the micro-tensile bond strength when two self-etching adhesives were used with different techniques. Flat dentine surfaces were prepared using either medium grit diamond burs or tungsten carbide burs. Ten specimens from each prepared surfaces were subjected for smear layer evaluation under SEM. Forty specimens from each of the prepared surfaces were further divided into two groups, bonded with either Clearfil SE Bond (SE) or Clearfil S3 Bond (S3) using one of four applications (as manufacturer's instructions, agitation, reapplication, and increased application time), restored with composites and subjected to a micro-tensile bond strength test. Smear layers created with diamond burs were thicker than those created with tungsten carbide burs. Surfaces prepared with tungsten carbide burs produced a higher bond strength than those prepared with diamond burs and the same type of adhesive resin. SE demonstrated a higher bond strength than S3 for all surfaces. S3 applied with the agitation technique demonstrated a higher bond strength to dentine prepared with tungsten carbide and diamond burs than that applied with other techniques. SE applied with increased time on dentine treated with carbide burs produced the highest bond strength. In conclusion, a thick smear layer decreased bond strength to dentine, and this might be improved by modification of application technique. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. [source] Quantitative misorientation characteristics of interphase boundaries in compositesJOURNAL OF MICROSCOPY, Issue 1 2006K. SZTWIERTNIA Summary Specific crystallographic correlations between neighbouring grains in composites were established by the use of selected area electron diffraction in the transmission electron microscope. However, it was the development of orientation mapping techniques that made it possible to obtain a quantitative description of the distribution of boundaries between the grains of both the same phase and different phases. This study shows that orientation topography measurements made by electron backscatter diffraction in the scanning electron microscope allowed determination of the crystallographic relationships between grains of different phases. An alumina-based composite with a content of 10 vol% tungsten carbide was chosen for investigations. Misorientation distribution functions were calculated to describe the distribution density of misorientations with respect to the nearest neighbouring measured point located in the grain of the second phase. The analysis of misorientation distribution functions permitted the evaluation of preferences for some special crystallographic correlations between the grains of composite matrix and inclusions as well as shares of interphase boundaries characterized by those correlations. [source] Plasma Synthesis of Tungsten Carbide Nanopowder from Ammonium ParatungstateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2009Taegong Ryu A thermal plasma process has been applied to the synthesis of nanosized tungsten carbide powder with ammonium paratungstate (APT) as the precursor. The reduction and carburization of vaporized APT produced nanosized tungsten carbide (WC1,x) powder, which sometimes contained a small amount of W2C phase. The effects of reactant gas composition, plasma torch power, the flow rate of plasma gas, and the addition of secondary plasma gas (H2) on the product composition and particle size were investigated. The produced tungsten carbide (WC1,x) powder was <20 nm in particle size. The synthesized powders were also subjected to a hydrogen heat treatment to fully carburize the WC1,x and W2C phases to the WC phase as well as to remove excess carbon. Finally, WC powder of particle size <100 nm was obtained. [source] Entwicklung hochverschleißbeständiger wolframschmelzkarbidbasierter Schichten auf Aluminiumbauteilen durch Plasma-Pulver-Auftragschweißen,MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 7 2007S. Kondapalli Dipl.-Ing. plasma transferred arc welding; wear-resistant coating; aluminium; composite coating; fused tungsten carbide Abstract Durch den Einsatz von Wolframschmelzkarbid können Funktionsflächen von Bauteilen mit stark abrasiven Beanspruchungen wirkungsvoll geschützt werden. Bereits seit vielen Jahren wird Wolframschmelzkarbid eingesetzt, um die Verschleißeigenschaften von Stahl zu verbessern. In diesem Artikel werden Ergebnisse von Untersuchungen zum Verschleißschutz von Aluminiumoberflächen mithilfe des Plasma-Pulver-Auftragschweißens von wolframschmelzkarbidbasierten Schichten vorgestellt. Die Wolframschmelzkarbid-Schichten werden mit zwei Methoden entwickelt, zum einen durch Dispergieren von Wolframschmelzkarbidpartikeln, zum anderen durch eine Kombination aus Dispergieren und Legieren von Verbundpulvern auf Wolframschmelzkarbidbasis. Die Schweißbarkeit der Pulversysteme wird für variierende Auftragschweißparameter und Karbidpartikelanteile untersucht. Im Anschluss erfolgt die Analyse der spezifischen Eigenschaften und der Verschleißbeständigkeit der entwickelten Schichten. Abschließend wird das Anwendungspotenzial am Beispiel von Führungsrollen dargestellt. Development of high wear-resistant FTC-based coatings on aluminium components using plasma transferred arc welding Nowadays, functional surfaces of components can be effectively protected from extreme wear with the help of fused tungsten carbide (FTC) coatings. The wear protection of steel components using FTC has been well known for many years. This paper presents the feasible study of improving the wear resistance of aluminium components with FTC particles using plasma powder arc welding. The FTC coatings are developed with two methods: one is the dispersion of carbide particles in aluminium and the other one is the combination of dispersing and alloying of FTC-based composite powders. In this research, coatings within a thickness range of a few millimeters are developed with varying process parameters and compositions of the filler materials. The developed coating systems are tested with regard to their specific properties and their wear resistance. Finally, their application potential is presented. [source] Microstructure Characterization of Tool Steel Claddings Co-Extruded on Low Alloyed Steel Substrates,ADVANCED ENGINEERING MATERIALS, Issue 5 2009Pedro Augusto da Souza e Silva Low-alloyed steel bars are hot extruded with pre-sintered tool-steel powders with or without the addition of tungsten carbides (W2C/WC) as hard particles. An extrudate is formed consisting of a wear resistant coating layer and a bulk steel bar as the substrate core. The microstructure at the interface between coating and substrate of different coatings is characterized using OM, SEM and EBSD. [source] |