The investigation and use of colloid-electrolyte baths from the time of first, publications had proceeded mainly in the field of working out highly efficient baths with low concentrations of electrolytes in connection with acute ecological necessity, saving energy and profit. We call briefly colloid-electrolytes such plating baths, where metal deposits are formed by reducing not only metal ions but also colloids and fine dispersions of this metal compounds. This dispersions in the field of the cathode (in the part of diffusion layer where the rate of stirring usually tends to zero) may be treated in certain optimal cases as the systems of mobile pores, giving rise to electrokinetic phenomena, equilibrium and nonequilibrium and thus to efficient stirring this part of diffusion layer, difficulties of the electrochemically reacting species transfer through which are the main obstacle for the cathode processes intensification. It results in reducing or eliminating the diffusion control and gives the essential rise of the limiting current densities. There was observed in some cases for chloride colloid electrolytes the correlation between decrease of polarization in comparison with conventional baths and degree of operating current densities increase. In chloride solutions colloids and fine dispersions, especially protected ones, are more stable than in solutions, where multi charged anions prevail. The polarization's decrease in chloride electrolytes was investigated also. We tend to explain the referred to phenomena by lessening the diffusion control in presence of mobile pore's systems of reducing to metal at the cathode colloids and fine dispersions of that metal's compounds.
The composition of the electrolyte-colloid was optimized by the method of mathematical planning of extreme experiments of Box-Wilson to obtain a composite electrochemical coating of nickel-nanodiamond. Polarization researches have shown a decrease in polarization in electrolytes containing diamond nanoparticles. The effect of the colloidal phase introduced into the electrolyte or formed during the electrolysis process on the electroplating process and the quality of precipitation was discussed. The wear resistance, microhardness, corrosion resistance of these deposits was investigated. These semi-bright and wear-and corrosion-resistant (Corrodcote-test) coatings are recommended as a substitute for electroplated chromium (better ecology). The morphology and surface of electroplating nanoparticles based on nickel were investigated using the «semi-contact» method on a PHYWE atomic force microscope. The leveling effect of diamond nanoparticles is shown.
The article presents the results of investigates of the effect of ultrafine additives (zirconium diboride, silicon carbide, diamond) on the physical and mechanical properties of composite electrochemical nickel deposits obtained from colloid-electrolyte baths. It was revealed that the most effective nanostructured additives are zirconium diboride and ultrafine diamond. Current efficiency and potentiostatic researches shew mutual participation of finely dispersed nickel hydroxide compounds in the formation of a composite electrochemical deposits and dispersed phase of zirconium diboride or ultrafine diamond that are attendant in the solution or formed during electrolysis and introduced into the electrolyte. It is shown that the optimal values of internal tensions and microhardness are associated with the hardening of the nickel matrix together with various nano-dispersed additives that are included in the deposit. These deposits can be used as an alternative to chrome deposits on parts of machinery.
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