Synthesis and characterization of WC-Co nanocomposites by novel chemical method

Nanocrystalline WC-Co cemented carbides containing different proportions of cobalt, i.e. 5, 10 and 15 wt.%, were prepared by chemical route. Another series of these composites containing 10 wt.% of cobalt with 5 wt.% Fe or Mn or Zn or Ni were also prepared by the same method. Polyacrylonitrile and tungestic acid were used as a source of carbon and tungsten, respectively. Phase composition, crystallite sizes and microstructure evaluation were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). The results revealed that the present chemical method is effective route to synthesize nanocrystalline WC-Co composites. By doping Co and/or Fe or Mn or Zn or Ni in WC-Co nanocomposite, nanocrystalline cemented carbide with inhibited grain growth were obtained. XRD showed peaks characterizing WC and Co in case of WC-15 wt.% Co, but showed addition peaks characterizing some oxides of tungsten and cobalt with W metal in case of WC-10 wt.% Co and/or 5 wt.% Fe of Mn or Zn or Ni. The crystallite size of the prepared WC-15 wt.% Co and heat-treated at 1000 degrees C was in the range of 1.1-7.4 nm, while it was 12-50 nm for WC-Co containing Fe or Mn or Zn or Ni as detected from XRD. On the other hand, the particle size was in the range of 200-400 and 300-500 nm, respectively, as detected from TEM and SEM. (c) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.