Tungsten Carbide and Vanadium Carbide Nanopowders Synthesis in DC Plasma Reactor
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Tungsten Carbide and Vanadium Carbide Nanopowders Synthesis in DC Plasma Reactor A. V. Samokhin • N. V. Alekseev • S. A. Kornev • M. A. Sinaiskii Yu. V. Blagoveschenskiy • A. V. Kolesnikov
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Received: 25 June 2012 / Accepted: 11 March 2013 / Published online: 26 March 2013 Ó Springer Science+Business Media New York 2013
Abstract Air–methane and nitrogen–hydrogen DC thermal plasma confined flows were used to synthesize tungsten carbide and vanadium carbide nanopowders. The influence of input process parameters such as C/W and C/V molar ratio, plasma jet chemical composition, plasma jet enthalpy, and reactants flow rates on the average nanoparticle size, chemical and crystallographic phase compositions were investigated. During post heat treatment, the synthesized MeC1-x nanopowders were fully carburized to monocarbides WC and VC with particles size less than 80 and 40 nm correspondently. Keywords synthesis
High-temperature alloys Chemical vapour condensation Plasmachemical
Introduction Tungsten carbide–cobalt hard materials (WC–Co) are widely used for a variety of machining, cutting, drilling, and other applications. The manufacturing of cemented carbides is based on the compacting of tungsten carbide and cobalt powders with addition of grain growth inhibitors such as vanadium, chromium and tantalum. The properties of WC hard metals such as hardness, strength, toughness, thermal conductivity and abrasion resistance can be extensively varied by grain size. The microstructure and grain growth of cemented tungsten carbides affect the material’s mechanical and physical properties. The grain size and grain distribution will also affect the material’s wear resistance and fracture toughness.
A. V. Samokhin N. V. Alekseev S. A. Kornev M. A. Sinaiskii Yu. V. Blagoveschenskiy Baikov Institute of Metallurgy and Material Science, Russian Academy of Sciences, Moscow, Russian Federation A. V. Kolesnikov (&) Tshwane University of Technology, Pretoria, Republic of South Africa e-mail: [email protected]
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Plasma Chem Plasma Process (2013) 33:605–616
Very fine WC powders are attractive for use in hard metals because fine grained alloys exhibit higher hardness than coarser grained ones of the same composition, at the same toughness level [1]. Recently significant attention of researchers was attracted to the nanosized particles. Nanoscale particles (1–100 nm) usually have physical properties different from those of large particles (10–100 microns) or the molecular/atomic species. It has been found that nanoparticles exhibit a variety of previously unavailable properties, depending on particle size, including magnetic, optical, and other physical properties as well as surface reactivity [2–4]. Previous investigations [5–7] have shown that the reduction of tungsten carbide grain size provides a significant improvement in the mechanical properties. The sintered materials with ultrafine grain sizes have extremely high flexural strength. Hard alloys obtained from nanocrystalline WC powders have a higher micro
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