Synthesis and processing of nanocrystalline tungsten carbide: Towards cemented carbides with optimal mechanical properties |
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Authors: | V. Bonache,M.D. SalvadorD. Busquets,P. BurgueteE. Martí nez,F. Sapiñ aE. Sá nchez |
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Affiliation: | a Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022, Valencia, Spainb Institut de Ciència dels Materials de la Universitat de València, Apartado de Correos 2085, E-46071, València, Spainc Instituto de Tecnología Cerámica, Campus Universitario Riu Sec. Vicent Sos Baynat, s/n. E12006, Castellón, Spain |
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Abstract: | Nanocrystalline tungsten carbide has been obtained by reduction/carburization at low temperature from precursors obtained by freeze-drying of aqueous solutions. Nanocrystalline WC powders with a adequate content of carbon were mixed with submicrometric Cobalt powder (12 wt.%), obtained by same synthesis method, and sintered in vacuum furnace. The cemented carbides fabricated from experimental powders were compared with both commercial ultrafine and nanocrystalline WC-12Co mixtures consolidated by the same route. The synthesised powders were characterized by X-ray powder diffraction, elemental analysis and scanning and high resolution transmission electron microscopy. On the other hand, density, microstructure, hardness and fracture toughness together with X-ray diffraction analysis of the sintered materials were evaluated. The cemented carbides obtained from synthesised powders exhibited a WC platelet-based homogeneous microstructure. This anisotropic growth might be due to the presence of stacking faults parallel to the basal plane in the starting WC powder, which would promote the defect-assisted preferential growth. These materials showed excellent mechanical properties, with a superior hardness/fracture toughness combination compared to materials prepared from commercial mixtures. |
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Keywords: | Freeze-drying precursors Nanocrystalline WC Cemented carbides Platelets Mechanical properties |
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