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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.

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This paper investigated the influence of various processing parameters of atmospheric pressure plasma jet (APPJ) on the etching behavior of PVA films. The etching rate increased as output power, and moisture regain increased. As the treatment time increased, the etching rate increased initially and then decreased. Atomic force microscopy (AFM) results showed that the surface roughness varied as the moisture regain (MR) (2.45%, 9.32%, and 78.31%, respectively) of PVA films changed during APPJ treatment. It was found that higher moisture regain and lower thermal conduction of underlayer had negative effect on the solubility of plasma treated PVA films.

The spindle or spherical cobalt oxalate powders were prepared by conventional precipitation in the presence of pulsed electromagnetic field (PEMF). The morphology and phase structure were characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The aspect ratio and surface fractal dimension of cobalt oxalate aggregate were calculated using Image tool software and Differential Box Counting (DBC) algorithm. The results indicate that the products prepared from ammonium oxalate and cobalt chloride give rise to the formation of β-CoC2O4∙2H2O. With the increase of pulsed time, the morphology of cobalt oxalate sample varies periodically from rod-like to spheroidic. For the sample treated for 60 s, the degree of sphericity is the highest. The surface fractal dimension is 2.096 and the corresponding fractal form is tight type.