Optimization of Plasma Electrolytic Oxidation Technological Parameters of Deformed Aluminum Alloy D16T in Flowing Electrolyte

Abstract

The prospects of plasma electrolytic oxidation (PEO) technology applied for surface hardening of aluminum alloys are substantiated. The work aims to optimize the technological process of PEO for aluminum in flowing electrolyte. The design of the equipment and the technological process of the PEO for aluminum deformed alloy D16T in flowing silicate–alkaline electrolyte have been developed. Oxide coatings were formed according to various technological parameters of the PEO process. The properties of the oxide coatings were evaluated, respectively, by measurements of coating thickness, geometric dimensions of the samples, microhardness, wear tests, and optical and scanning electron microscopy. To study the influence of the technological parameters of the PEO process of forming oxide coatings on geometrical, physical, and mechanical properties, planning of the experiment was used. According to the results of the conducted experiments, a regression equation of the second order was obtained and the response surfaces were constructed. We determined the optimal values of the technological parameters of the PEO process: component concentration ratio (Na2SiO3/KOH), current density, flow rate, and electrolyte temperature, which provide the oxide coating with minimal wear and sufficiently high physical and mechanical properties and indicators of the accuracy of the shape of the parts. The research results showed that the properties of oxide coatings mainly depend on almost all constituent modes of the PEO process. Samples with Al2O3 oxide coating were tested during dry friction according to the “ring–ring” scheme. It was established that the temperature in the friction zone of aluminum samples with an oxide coating is lower compared to steel samples without a coating, and this indicates high frictional heat resistance of the oxide coating.

Analytical Model of Deformation of a Functionally Graded Ceramic Coating under Local Load

“…However, these intermetallics lead to microelectrochemical inhomogeneity of the alloy, which leads to pitting corrosion, intergranular corrosion or delamination. Therefore, deformed alloys of such a system are used clad with a layer of aluminum and/or subjected to PEO [7].…”

“…Thus, the composition will be destroyed by the cracking of the oxide layer. Therefore, deformed alloys of such a system are used clad with a layer of aluminum and/or subjected to PEO [7].…”

“…In particular, ceramic coatings are widely used in many industries due to their wear resistance, chemical resistance and thermal properties. Their fields of application vary from instrumental, energy and aviation engineering to medicine and semiconductor manufacturing [5][6][7]. In detail, we note that ceramic coatings include hard coatings, anti-corrosion coatings, wear-resistant coatings and heat-protective coatings, which are often used in engineering today [8].…”

The Tribological Properties of Plasma Electrolytic Oxidation Layers Synthesized on Arc Spray Coatings on Aluminum Alloys in Contact with Various Friction Materials

“…Its use makes it possible to obtain multifunctional layers (similar to ceramics) with a unique set of properties. PEO layers have high wear resistance, corrosion resistance and heat resistance, as well as electrical insulating and decorative properties [29][30][31][32][33][34]. Depending on the chemical composition of the aluminum alloys, PEO layers with different contents of α, γ, δ and η phases are formed on their surface.…”

Protection of AA2024 alloy against wear and corrosion by HVAF sprayed AlCuFe coating

“…However, the wear/friction behaviour and especially anti-corrosion performance of these alloys need to be further enhanced to increase the operational life of the aluminium products. The operational properties of the aluminium products can be improved by several surface modification techniques [1][2][3] that allow to produce the nitride [4], oxide [5,6], and intermetallic [7,8] coatings of high hardness, rigidity, and wear/corrosion resistance.…”