Papers by Author: M.G. Pavlović

Abstract: In this paper the morphology of Ni-Co powders electrodeposited from ammonium sulfate-boric acid containing electrolyte is investigated as a function of alloy powder composition. Composition of the electrolyte, i.e. the ratio of Ni2+/Co2+ concentration is found to influence both, the alloy phase composition and the morphology of Ni-Co alloy powders. At the highest ratio of Ni2+/Co2+ ions concentration, typical 2D fern-like dendritic particles were obtained. With decrease of Ni2+/Co2+ ions ratio among 2D fern-like dendrites, 3D dendrites and different agglomerates of a size of about 100 μm, being either compact (typical for pure Co powder) or composed of a large number of small 3D dendrites on their surface were obtained. According to the X-ray analysis, with decreasing Ni2+/Co2+ concentration ratio the amount of f.c.c. β-Ni phase was found to decrease, while the amount of h.c.p. α-Co phase was found to increase being accompanied by the appearance of the f.c.c. Co phase at Ni2+/Co2+ = 0.33.

Abstract: The surface structure of powder particles, which allows free flow of copper powder, was examined. It has been shown that a sufficiently dense surface structure which permits free flow will be obtained if apparent density is higher than 2.2 – 2.3 g/cm3. Such a surface structure can be obtained by reversing current electrodeposition of powder at considerably lower apparent densities of powder due to selective dissolution of subparticles during anodic time of reversing current wave. The surface structure of copper powder particles is discussed and correlated with the lowest apparent density at which the copper powder can still flow.