Synthesis of Spherical and Fine Cobalt Powders from Cobalt Oxalate

Spherical and fine cobalt powders were prepared by thermal decomposition of cobalt oxalate precipitated in the presence of pulsed electromagnetic field (PEMF). The morphology and phase structure were characterized by scanning electron microscopy (SEM), atomic force microscope (AFM) and X-ray powder diffraction (XRD). The aspect ratio was calculated by image tool software and the average size of cobalt particles was measured by laser particle size analyzer. The results indicate that both products prepared from cobalt oxalate with or without PEMF give rise to the formation of β-Co. The morphology of both products is similar to that of the precursors. The presence of PEMF plays an important role in formation of spherical and fine cobalt particles.

Characteristics of Pre-Alloyed Powders for Diamond Tools

In this paper, the fundamental attributes, phase composition of three pre-alloyed powders for diamond tools by water atomization were investigated. The density, hardness, bend strength and bending modulus of their sintered samples by hot pressing were examined under various temperatures. The results showed that the three pre-alloyed powders have excellent low temperature sintering characteristics. The physical and mechanical properties of the samples were found to be nearly the same as those of ultra-fine cobalt powders.