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

摘要

Nanocrystalline WC-Co cemented carbides containing different proportions of cobalt, i.e. 5, 10 and 15 wt. percent, were prepared by chemical route. Another series of these composites containing 10 wt. percent of cobalt with 5 wt. percent 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. percent Co. but showed addition peaks characterizing some oxides of tungsten and cobalt with W metal in case ofWC-10 wt. percent Co and/or 5 wt. percent Fe of Mn or Zn or Ni. The crystallite size of the prepared WC-15 wt. percent Co and heat-treated at 1000 deg 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.