Materials Science UDC 621.793:621.357.7 Проаналізовано підходи щодо застосуван- DOI: 10.15587/1729-4061.2019.171787 ня електрохімічних покривів в технологіях поверхневої обробки. Показано, що спрямова- не модифікування поверхні дозволяє розшири- DETERMINING FEATURES ти функціональні властивості оброблюваного матеріалу, зокрема підвищити показники міц- OF APPLICATION ності, зносостійкості, корозійної тривкості, каталітичної активності. OF FUNCTIONAL Запропоновано спосіб поверхневої обробки нелегованих сталей та чавунів шляхом фор- ELECTROCHEMICAL мування тонкоплівкових покривів тернарни- ми сплавами заліза та кобальту з молібденом COATINGS IN і вольфрамом. Показано, що введення туго- плавких металів до 37 ат. % в поверхневий шар призводить до зміни фазової структури TECHNOLOGIES OF покриття. Виявлено, що це забезпечує підви- щення зносостійкості на 40 %, мікротвердості SURFACE TREATMENT у 2,5–3,5 рази, а також зменшення коефіцієн- ту тертя в 3–4 рази порівняно з матеріалом A. Karakurkchi підкладки. Сформовані матеріали можуть PhD, Senior Researcher бути використані для зміцнення і захисту Department of General and Inorganic Chemistry* поверхонь в різних галузях промисловості. E-mail: [email protected] Для модифікування поверхні поршневих M. Sakhnenko силумінів запропоновано використовувати ме- Doctor of Technical Sciences, тод плазмово-електролітичного оксидуван- Professor, Head of Department ня із формуванням керамікоподібних покривів. Department of Physical Chemistry* Показано, що в гальваностатичному режимі M. Ved із лужних розчинів електролітів, що містять Doctor of Technical Sciences, Professor солі мангану та кобальту, можливо одержу- Department of General and Inorganic Chemistry* вати рівномірні щільні з високою адгезією до основного металу оксидні покриви, допова- I. Yermolenko ні каталітичними компонентами, вміст яких Doctor of Technical Sciences, Senior Researcher варіюється в межах 25–35 ат. %. Показано, що Research Laboratory* морфологія та фазова структура поверхневих S. Pavlenko шарів змінюється із інкорпорацією металів- PhD, Associate Professor допантів. Сформовані покриви мають високий Department of Technical and Logistics** ступінь розвинення поверхні, що є передумо- V. Yevsieiev вою підвищення їх функціональних властивос- PhD, Deputy Head of Department тей. Запропонований підхід використано для Department of Special Tactics Preparation** модифікування поверхні поршня КамАЗ-740. Встановлено, що використання керамікоподіб- Ya. Pavlov них покривів поршня двигуна приводить до зни- PhD, Deputy Head of Faculty ження годинної витрати палива та кількості Faculty of Logistics** токсичних речовин з відпрацьованими газами, V. Yemanov що робить їх перспективними для використан- PhD, Head of Faculty ня у внутрішньоциліндровому каталізі Faculty of Logistics** Ключові слова: поверхнева обробка, елек- *National Technical University «Kharkіv Polytechnic Institute» трохімічний покрив, функціональні властиво- Kyrpychova str., 2, Kharkiv, Ukraine, 61002 сті, ремонтне виробництво **National Academy of the National Guard of Ukraine Zakhysnykiv Ukrainy sq., 3, Kharkiv, Ukraine, 61001 1. Introduction tion, deformation, application of protective layers, films and coatings in various ways. This allows forming surface Formation of functional coatings combining corrosion layers with desired properties directly on the treated mate- resistance, hardness, wear resistance and catalytic activity rial and obtaining characteristics that exceed those of the is a crucial problem in the creation of new materials, the use base metal [1, 2]. of which largely led to progress in many fields of modern Essential interest in a surface modification is due to the technology. In particular, surface engineering combines fact that characteristics of the surface layers in combination methods of directed changes of physicochemical properties with the properties of the base metal determine properties of of the surface layers of structural materials by modifica- products in general. This approach is also attractive from an 29 A. Karakurkchi, M. Sakhnenko, M. Ved, I. Yermolenko, S. Pavlenko, V. Yevsieiev, Ya. Pavlov, V. Yemanov, 2019 Received date: 10.06.2019 Accepted date: 24.06.2019 Published date: 30.06.2019 Eastern-European Journal of Enterprise Technologies ISSN 1729-3774 3/12 ( 99 ) 2019 economic point of view in comparison with known methods additional components. The combination of valuable proper- of changing the volume characteristics of structural materi- ties of alloying components makes it possible to obtain coat- als and finished products. ings with enhanced corrosion resistance, microhardness, Surface treatment of machine parts and mechanisms is wear resistance on low-alloy steel and cast iron parts [10, 11]. widely used to improve the functional properties of materi- However, the number of such works is extremely limited, and als. Such technologies are highly efficient and resource-sav- the results are contradictory. ing. They are used in production and repair. In [12], Ni–Fe–Mo alloy coatings were obtained from The market of military and defense technologies puts a sulfate-citrate electrolyte on copper substrates. The forward very high requirements to structural materials used current efficiency was 10 %. The coatings with varying to manufacture models of weapons and equipment in general, thickness from 0.6 to 2.1 µm contain 25–40 wt. % Mo. their individual parts, components and assemblies. This is The resulting alloys have a crystal structure and exhibit due, above all, to harsh operating conditions, intense use, magnetic properties. need for rapid recovery of lost functions. Thus, surface mod- In a series of works on electroplating of multicompo- ification technologies, in which a coating with well-defined nent alloys of molybdenum and tungsten with metals of properties is formed on the treated surface are demanded. iron subgroup [13–17], the researchers propose a complex The scope of coatings of various functional purposes is very citrate electrolyte, рН 7.0–7.3 [13], to form Ni–Fe–Mo–W wide: corrosion protection, increase of strength, conductivi- coatings. The process is carried out using a rotating disk ty, heat and wear resistance, and so forth. electrode at a temperature from 25 to 60 ºС at a current Surface treatment methods can solve the issues of cor- density of 25–75 mA/cm2 [14]. The current efficiency of the rosion protection, increase of wear resistance, improvement alloy does not exceed 10 % [15]. According to the authors, co- of quality of machine parts, minimization of environmental precipitation of the components in the alloy occurs competiti- pollution, as well as many other problems [3–5], and can vely [16]. Analysis of surface morphology of the obtained be divided into several groups. These include modification, coatings based on SEM images suggests that they are uneven, application of films and coatings, combined methods, surface with a large number of irregular structures and cracks [17]. microtopography management. The coatings with a ternary Ni–Fe–Mo alloy of crystal The low consumption of the coating material and the in- structure with magnetic properties were obtained on copper creased surface characteristics of parts ensure prospects for substrates in the sulfate-citrate electrolyte [18]. The authors using special-purpose coatings and introducing them into draw attention to the change in molybdenum content in the manufacturing and repair practices [6, 7]. However, these coatings from 25 wt. % to 40 wt. % with a thickness of 0.6 to technologies are not widespread yet due to the significant 2.1 µm, respectively. cost and technological complexity. Of practical interest are the results of the authors’ stud- Therefore, the search for economically and technolog- ies [19] on the electrochemical synthesis of Fe–Co–W alloys ically available methods of surface modification of parts, with enhanced physicomechanical and anticorrosive proper- components and assemblies is a relevant practical task, the ties. The researchers note an increase in the microhardness solution of which will increase their operational properties of the coating up to 1,154 units (according to Vickers) with and expand the scope of application. the treatment temperature increase, and at T‒600 °C, the microhardness of the Fe–Co–W coating exceeds that of electrolytic chromium. 2. Literature review and problem statement The authors [20, 21] proposed binary Fe–Mo (W) and Fe–Cr alloy coatings with the content of alloying compo- Treatment technologies with the application of thin-film nents at the level of 3–7 %. For coating formation, sulfate coatings, in particular electrochemical, are quite common electrolytes of iron (II) with the addition of salts of alloying in the US defense industry. Manufacturing enterprises of components are used. The resulting coatings are character- military and civil equipment use electroplating with indi- ized by improved mechanical properties and can be used, in vidual metals (nickel, chromium, cadmium, silver, copper, particular, for hardening and restoration of valves and track- tin), anodizing of aluminum and its alloys, chemical precip- rod ends, as well as in repair. itation. The system of standards of the US Department of As for the parts made of valve metals and alloys on their Defense (MIL-SPEC) clearly regulates requirements to the basis, in particular aluminum, an effective method to form formation and properties (characteristics) of the obtained special-purpose coatings on them is plasma electrolytic thin-film materials