Yermolenko I. Scientific Basics of Electrochemical Technology For Applying Coatings Consisting of Ternary Iron Alloys with Refractory Metals

The subject of this research is chemical and electrochemical processes in the electrolyte and on the interphase boundaries during the formation of ternary alloys of iron and cobalt with tungsten or molybdenum. The research objective is the development of scientific basics for electrochemical technologies used for the application of functional coatings consisting of ternary iron and cobalt alloys combined with molybdenum and tungsten. Research methods ‒ linear voltammetry, X-ray fluorescence and energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, electrode impedance spectroscopy, atomic force microscopy. As the result of theoretical and bottom line it has been established the mechanism and kinetics of co-deposition of iron and cobalt with tungsten and/or molybdenum into ternary alloys. The variation schemes of electrochemical processes were suggested and these allow for the deposition of Fe-Mo-W and Fe-Co-W(Мо) coatings depending on their practical application with the combined realization of improved corrosion resistance, microhardness, electrocatalytic activity and magnetic properties in surface layers. The novelty is The hypothesis as for the competitive reduction of iron ternary metals with refractory components when co-deposition into ternary alloys preconditioned by the mutual interaction of thermal-&-dynamic and crystal-&-chemical characteristics of the alloy-forming metals and the kinetic parameters of cathode process and it was proved experimentally. The influence of composition of electrolytes and modes of electrolysis on elemental, phase composition and surface morphology of the obtained coatings has been determined. The possibility of controlling the composition and morphology of multicomponent coatings on the basis of iron and cobalt by varying the composition of the electrolyte (the ratio of component concentrations, the ratio of ligand and complexing agent), and by used of galvanostatic and pulsed electrolysis regimes with a ranging of current density 2.5 ‒ 6.5 A/dm2, and durations pulse/pause 5 ‒ 10 / 5 ‒ 20 ms, has been proved. The realization degree consist of the experimental items with developed coatings and electrolyte compositions pilot test in Joint Stock Company «Kharkov Tractor Plant», PJSC «UKRNDICHIMMASH», the Department for Metals and Semiconductors Physics at the Education and Science Institute for Engineering and Physics NTU «KhPI» and at the Metrology Center of Military Standards of the Armed Forces of Ukraine. The branch of this research application is the technical process of electrochemical production, Research Studies Institutes and а training process.