Sknar Y. Electrodeposition of iron group metals, iron group-based alloys and composites from methanеsulfonate electrolyte

The doctoral thesis is devoted to identifying the general regularities of electrodeposition of iron group metals and iron group-based alloys and composites from a methanеsulfonate electrolyte, to studying the influence of the electrolyte composition and electrolysis parameters on their composition, structure, physicochemical properties, and to the development of generalizing principles for the task-oriented adjustment of the main factors of their electrodeposition. The kinetic regularities of electrodeposition of the iron group metal ions from methanesulfonate electrolytes at solid and mercury electrodes have been revealed. It has been found that the electroactive particles are predominantly metal hydroxo-complexes in the region of low potentials, and metal aqua complexes in the region of high potentials. A mechanism of electrochemical reduction of the iron group metal ions has been proposed, which adequately describes the experimental data. The general regularities of codeposition of iron group metals have been revealed, which find an adequate explanation provided the electroactive particles in this process are hydroxo-complexes of the corresponding metals. A mechanism of the composite coating formation has been proposed, which takes into account the different rates of metal matrix electrodeposition at an electrode surface that is free from or conditionally occupied with particles. The reaction mechanism of the phosphorus formation during electrodeposition of the Ni-P alloy from the methanesulfonate electrolyte was established. It was found that an increase in the near-electrode layer pH due to the reactions of phosphorus formation leads to an increase in the concentration of electroactive hydroxo-complexes of nickel and to a decrease in the overpotential of nickel deposition into the alloy in comparison with the pure metal. A method for obtaining nanocomposites from true methanesulfonate electrolytes containing polyvalent metal ions has been proposed. The proposed method implies the formation of a nano-sized oxide-hydroxide disperse phase directly during electrolysis as a result of an increase in the near-electrode layer pH.