Військовий інститут танкових військ НТУ "ХПІ"

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Corrosion properties of galvanic Fe–Mo(W), Fe–Mo–W coatings
(Науково-технологічний комплекс "Інститут монокристалів", 2019) Ved, M. V.; Sakhnenko, N. D.; Karakurkchi, A. V.; Pershina, K. D.; Yermolenko, I. Yu.
The methods of analysis of polarization dependences, the electrode impedance spectroscopy and gravimetry were used for the investigation of the corrosion properties of galvanic binary Fe–Mo(W) and ternary Fe–Mo–W coatings in the media of a different acidity. It was shown that the corrosion rate of Fe–Mo–W and Fe–Mo(W) alloys is decreased with an increase in the pH of the solutions and with the enrichment of the alloys by doping refractory components. The dependence of the control of corrosion process on the composition of electrolytic alloys has been specified. It was established that the corrosion resistance of binary alloys is 1.1 to 1.5 orders of magnitude higher in comparison with the parameters of substrate materials, in particular the mild steel. The corrosion resistance indices for the coatings applied using the ternary Fe–Mo–W alloys substantially prevail over those for mild steel, individual metals and binary Fe–Mo and Fe–W coatings. The corrosion resistance of Fe–Mo–W system is equal to 8300 Ohm·cm² and it is conditioned by the formation of the two-component layer film consisting of molybdenum oxides and tungsten oxides. Using the data of gravimetric investigations we constructed the diagrams "the corrosion depth index kh, mm/year – the composition" for the Fe–Mo–W system that allow us to define the metal content ratio for Fe–Mo(W), Fe–Mo–W alloys in order to provide an appropriate corrosion resistance depending on service conditions.
The electrochemical behavior of Fe³⁺ – WO₄²⁻ – Cit³⁻ and Fe³⁺ – MoO₄²⁻ – WO₄²⁻ – Cit³ systems
(Украинский государственный химико-технологический университет, 2017) Yermolenko, I. Yu.; Ved, M. V.; Karakurkchi, A. V.; Sakhnenko, N. D.; Kolupayeva, Z. I.
The kinetic parameters of electrochemical behavior of tungsten at the deposition of Fe–W and Fe–Mo–W alloys were determined using linear voltammetry and analyzing polarization relationships. In the presence of citrate ions the cathode process was shown to proceed with the participation of [FeHCitWO₄]⁻ clusters. An optimal concentration ratio of the components in electrolyte required for the Fe—W alloy deposition was defined as c(Fe³⁺):c(Cit³⁻):c(WO₄²⁻) = 1:1.5:0.3. The deviation from this ratio by an increase in the concentration of tungstate ions results in the formation of dimer forms W₂O₇²⁻ and [FeW₂O₇HCit]⁻ clusters; as a result the concentration of electrode active particles [FeWO₄HCit]⁻ diminishes and the cathode process is inhibited. A peculiar feature of the formation of electrolytic alloy Fe–Mo–W is a competitive reduction of molybdates and tungstates. Based on the analysis of the kinetic parameters and characteristic criteria of electrochemical reactions, we proposed the mechanism for the co-deposition of alloy containing iron with molybdenum and tungsten; this mechanism is a sequence of coupled reactions of irreversible reduction of intermediates with slow charge transfer stage and previous chemical step of the ligands release. The data of X-ray phase analysis show that the binary alloys Fe–W are solid solutions of tungsten in iron and ternary alloys Fe-Mo- W are X-ray amorphous.
Electroplating and functional properties of Fe-Mo and Fe-Mo-W coatings
(Украинский государственный химико-технологический университет, 2014) Ved, M. V.; Sakhnenko, N. D.; Karakurkchi, A. V.; Yermolenko, I. Yu.
Peculiarities of electrodeposition Fe-Mo and Fe-Mo-W coatings from citrate bath containing iron (III) on substrates of mild steel and cast iron are investigated. The utilization of iron (III) compounds significantly enhanced the stability and service life of electrolyte due to elimination redox reactions involving complexing and side anodic reactions. The effect of alloying components salt concentration and electrolysis mode on the quality, composition and properties of the alloys were determined. It is shown that alloys formed in nonstationary electrolysis have a uniform surface, composition and a lower content of impurities. Increased physical and mechanical properties as well as corrosion resistance of Fe-Mo and Fe-Mo-W coatings compared with the base metal are caused by the presence of propensity for passivation alloying components as well as by amorphous structure of electroplating alloys. Indicated coatings can be considered as promising in surface hardening technologies and repair of of worn items.

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