The development of the modern industry requires to develop high-performance, environmentally friendly methods for the production of light structural material surface coatings. The use of products and structures made of titanium and its alloys with high wear resistance and corrosion resistance prevails in many industries, in particular in the aerospace industry, shipbuilding, and transport engineering. Nowadays, the application of the plasma electrolytic oxidation method, a promising metal surface treatment method, is of increasing interest. Besides this method is called microarc oxidation. The objective of this work is to study the properties of oxide coatings obtained on titanium alloys under the influence of rapid pulsed effects of the plasma electrolytic oxidation process. Oxide composite coatings were obtained in various electrolyte solutions in this work. Oxide coatings are characterized by high wear resistance. It has been established in tribological tests that the wear resistance of the coating is increased by 2-15 times compared with an uncoated sample. The friction coefficient curves obtained for coated samples show that there is no destruction of the coating to the base. The breaking-in area is marked in the curves. The friction surfaces are adjusted to each other and go to a stable friction mode. The latter results in the friction coefficient decrease and wear rate decrease.

This paper studies the impact of rapidly flowing impulse effect of electrolytic plasma oxidation on physical and mechanical specifications of oxide coatings through the surface modification of VT1-0 titanium alloy. The present mode allows obtaining dense coatings with high mechanical properties. The electrolytic plasma oxidation process implementation leads to micro arc-discharge emergency in a short period through the small duration values of 250 µs anodic impulse. The achieved oxide coatings have high wearing features. Frictional testing resulted in wearing features increase in 4-15 times comparing to the sample off coating at to15 µm oxide layer thickness. Friction coefficient curves of oxide coating samples have shown no destruction of the coating to the bottom. A run-in area is recognized on the curves; sliding surfaces adapt to each other and pass to the stable friction regime. The later leads to the friction coefficient reduce and wear intensity reduction.

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The necessity and possibility of using nanoindentation in studying the physical and mechanical properties of plasma-hardened wheel steel are considered. The goal of the study is demonstration and substantiation of significant differences in the mechanical properties and behavior of the materials in nanoscale tests from those determined in traditional macroscopic tests. The method was implemented using a NanoHardnessTecter nanohardness tester. The electric field formed in the nanoscale hardness tester pressed on the indenter and the diamond tip of the indenter is immersed in the surface layer of the material under study. The characteristics of the surface layer are determined using the developed software. Knowledge of the physicomechanical characteristics of the material (hardness, Young’s modulus, elastic recovery, etc.) which affect the wear resistance of the surface layers, allows one to evaluate and select the optimal surface modification technology using plasma hardening. The credibility of determination depends on the parameters of measuring equipment and compliance with the requirements to the depth of the imprint depending on the thickness of the hardened layer. The studies were carried out on the samples cut from the rim and crest of a railway wheel subjected to surface plasma hardening on a UPNN-170 installation (Russia). It is shown that the hardness (according to Vickers HV and H) of the rim is greater, and Young’s modulus, on the contrary, is less than the corresponding characteristics of the crest. Moreover, the wear resistance of hardened structural steel increases after nanostructural friction treatment.

The use of structures made of titanium and its alloys, which have improved corrosion, physical and mechanical properties, are in demand in many industries. In this regard, the processes of modifying the surface of metals are of interest. One of the modern and promising methods of metal surface treatment is plasma electrolytic oxidation. Currently, there is a problem of widespread use of this process when DC modes are used in the implementation of the process. This is due to the large consumption of electricity. The purpose of this work is to study the morphological and corrosion properties of oxide coatings obtained in the pulsed anode-cathode mode on titanium alloys VT1-0 and VT5 in various electrolyte solutions. Modification of the surface of titanium alloys was carried out at the duration of the anode current pulse of 250 ± 25 microseconds, the duration of the cathode current pulse of 5 ± 0.5 ms, the repetition frequency of the anode and cathode pulses of 50 ± 0.5 Hz. Alkaline solutions served as electrolytes. Oxide coatings obtained in various electrolytes are characterized by different porosity and coating thickness. Coatings with a finely porous structure, with an average pore diameter from 0.09 microns to 0.4 microns, and larger pore sizes of 0.6 – 0.7 microns were obtained. The porosity of the coatings ranges from 6.12% to 12.2%. According to the data of energy dispersion analysis, it was found that the structure of oxide coatings includes both components of the processed metal and components of the electrolyte solution. The main components, in this case, are oxygen and processed metal, as well as other elements such as boron, phosphorus, aluminium, fluorine, sodium, silicon and others. Corrosion tests according to GOST 9.308-85 under the influence of neutral salt mist at a temperature of (35 ± 2) °C with 1500 hours in the Ascott CC 450 chamber, it was shown that there was no corrosion damage to the coatings.