The Characteristics of Electrochemically Produced Powder A General Discussion

3 The Characteristics of Electrochemically Produced Powder A General Discussion 

Comparative survey of powders obtained in potentiostatic and galvanostatic regimes of electrolysis is shown in Fig. 6.4. In spite of the fact that particles obtained by galvanostatic deposition are less dendritic than those obtained by potentiostatic deposition due to smaller overpotential at the end of the galvanostatic than the potentiostatic regimes [5], there is no any substantia] difference in the morphology of powder particles obtained between these two constant regimes of 

Due to the ionic equilibrium of the species in the CUSO4-H2SO4-H2O system (the most often employed electrolytes for the electrodepositiOTi of copper are sulfate ones), the shape of powder particles depends on CUSO4 and H2SO4 concentrations [32-34]. For a constant H2SO4 concentration, the ion concentration decreases with increasing Cu concentration that is manifested by the change of shape of powder particles from the cauliflower-like to dendritic (Mies. 

Of course, hydrogen evolution affects mechanism of formation of powder particles. The dendrites are formed without, as weU as with, a quantity of evolved hydrogen (the case of Cu) which was insufficient to achieve any effect on the hydrodynamic conditions in the near-electrode layer. Then, the electrodeposition process was primarily controlled by the diffusion of ions to the electrode surface, rather than the kinetic of the electrodeposition [5,6], The cauUflower-Uke particles are formed in the conditions of vigorous hychogen evoluticMi with the strong effect of evolved hydrogen on the hydrodynamic conditions in the near-electrode layer, and the concept of effective overpotential is proposed to explain formation of these particles [25, 35]. 

Finally, hychogen evolution becomes crucial factor determining the shape of powder particles of the group of the inert metals, and the concept of effective overpotential is applicable to explain the formation of these powder particles. Due to vigorous hychogen evolution, dendritic growth is almost completely inhibited. Analysis of the polarization curves for Co and Ni [12, 26, 30] showed that their 

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