Preparation and Characterization of Ultra-Fine Cobalt Powder

Ultra-fine cobalt powder was prepared by liquid reduction method with Co(OH)(2) as raw material, ethylene glycol as solvent and reducing agent, and sodium dodecyl benzene sulfonate (SDBS) as dispersant. The effect of SDBS concentration on cobalt powder surface area, particle size and magnetic properties was studied. The obtained powder were characterized by specific surface area analysis, X-ray Diffraction (XRD), Fourier transform infrared spectrum (FTIR), vibration sample magnetometer (VSM), scanning electron microscopy (SEM). The result shows that specific surface area of the powder increases with the increase of SDBS dispersant concentration. When the concentration of SDBS is 7.5 g/L, the powder surface area is 8.1235 m(2)/g, and particle size is 0.5-0.6 mu m. It is uniform and nearly spherical without reunion; most are face-centered cubic (fcc) closest packing while few are hexagonal closest packing. Saturation magnetization, remanence magnetization and coercive field of powder decrease after adding SDBS dispersant, which are 39.52 and 132.93 A.m(2)/kg, 3.16 and 21.32 A.m(2)/kg, 15 302 and 23 347 A/m for powder with adding 7.5 g/L and without SDBS dispersant.