Vol 52, No 9 (2016)

The problems of nucleation at electrocrystallization of metals and alloys are considered. The thermodynamics and kinetics of nucleation in stationary and nonstationary modes, the atomistic approach to the formation of nuclei and their growth (isolated and overlapped), the dependence of the nucleation rate on the adsorption of surfactants, the deposit grain size as a function of overpotential, and the grain size of eutectic alloys are discussed. Conclusions are drawn on the most important factors which should be taken into account during the analysis of processes of electrochemical nucleation and cluster growth.

The mechanism responsible for the inclusion of Al₂O₃ and SiC nanoparticles, the mixture of Nb₂N and Ta₂N (1: 1), MoS₂, Cr₂O₃, and SiO₂ with diverse electric conductivity, hydrophilicity, and resistance to solution components in chromium deposits from the sulfate–oxalate suspension solutions based on Cr(III) was studied. The main factors that determine the formation of chromium composite electrochemical coatings, their composition, and surface morphology were determined. The film on the surface of the growing deposit of the intermediates of the reduction of chromium ions plays the key role in the formation of composite coatings from Cr(III) and Cr(VI) sulfate–oxalate suspension solutions. The film can play the role of a structural mechanical barrier that hinders the incorporation of particles in the deposit, or it can fix the particles on the electrode surface by creating hydroxo bridges with chemisorbed hydroxide compounds on the particle surface.

The methodology of electrochemial impedance is used for finding the characteristic function of the random time of the first encounter with the boundary by a process of electrochemical stochastic diffusion in an equilibrium ac circuit containing a double layer capacitance and a noisy charge-transfer resistance. The Nyquist diagram of the characteristic function suggests that the method of the first random encounter with the boundary by electrochemical stochastic diffusion may prove to be useful in the noise diagnosis of objects and devices of electrochemical power engineering and also in comparative studies of electrochemical corrosion processes.

The method of molecular–level computer simulation at the temperature of 298 K was used to study the fundamental regularities of formation of electric properties of the hydrate shell of the Na⁺ cation in a planar model nanopore with hydrophilic structureless walls in contact with water vapors. Electric polarizability changes nonmonotonously: as consistent with the changes in the molecular structure of the system. Hydration within the pore occurs in several stages, from formation of chain structures, microdrop compaction and ejection of the ion from its own hydrate shell to encapsulation and absorption of the ion by the solvent preceding formation of nanoelectrolyte. Despite the significant differences in the energy of retaining hydrate shells for Na⁺ and Cl^─ ions, polarizabilities of the two systems are close and behave similarly under variation of conditions. Strong spatial anisotropy of the polarizability tensor of the ion–hydrate complex is due to the effect of the nanopore walls on multiparticle spatial correlations in the system.