Abstract. Problem. MAO technology is well developed for aluminum alloys. As for titanium alloys, the MAO technology of surface hardening for them requires further research. Goal. In order to improve the mechanical characteristics of titanium alloys it is necessary to establish patterns of influence of regimes and electrolyte composition during MAO process on the phase composition, microhardness and tribological characteristics of coatings obtained by microarc oxidation of VT3-1 and PT-3V titanium alloys. Methodology. X-ray structural analysis (DRON-3) in radiation Кα-Cu, microhardness measurement (PMT-3) with 100 gr load, measurement of coating thickness (vortex thickness gauge BT-10NTs), tribological tests (SMC-2) was used. Results. The MAO treatment of the alloys was carried out in an alkaline electrolyte (KOH) with the addition of sodium aluminate (NaAlO2), sodium hexametophosphate (NaPO3)6 and water glass (Na2SiO3, ρ ≈ 1.4 g/cm3). A metallographic study of the cross section of titanium alloys with MAO coating made it possible to establish that the coating has a two-layer structure consisting of a technological (porous) and main (dense, base) layers. The results of X-ray diffraction analysis showed that the main phases of the coating are the phases TiO2 – rutile, TiO2 – anatase, as well as compounds Al2TiO5 – aluminum titanate. The specific volume of the formed oxides exceeds the volume of the titanium base on which it is formed. So, for TiO2 Voх/Vmet. ≈ 1.8; for Al2TiO5 – 4.4; for mullite – 13.9. This factor contributes to the formation of continuous coatings. It was established that in order to achieve the highest hardness, the presence of the NaAlO2 component in the electrolyte is necessary. This made it possible to achieve a hardness of 11000 MPa of MAO coating on VT3-1 alloy using an electrolyte of 1.75 g/L KOH + 1 g/L Na2SiO3 + 2 g/L NaAlO2. For the PT-3V alloy, the use of an electrolyte of a similar composition can achieve a hardness of 7500 MPa. It is shown that the use of MAO processing of titanium alloys allows to reduce the dry friction coefficient in the VT3-1 – SCh20 system to 0.1. Originality. The structure, phase composition and properties are determined by electrolysis conditions and coating thickness. Practical value. The results obtained are a recommendation for surface hardening of PT-3V and VT3-1 titanium alloys for their further use in friction elements.

Аннотация. В работе исследованы структура и свойства покрытий на титановых сплавах ПТ-3В и ВТ3-1, сформированных в электролитах различных типов (с добавлением КОН, NaAlO2, NaОН, (NaPO3)6, Na2SiO3) при анодно-катодном режиме методом микродугового оксидирования (МДО). Показано, что достичь высокой твердости 9000–11000 МПа возможно при использовании алюмината натрия (NaAlO2) в качестве составной электролита. Фазовый состав такого покрытия включает анатаз, рутил и титанат алюминия. Использование МДО-обработки титановых сплавов позволяет уменьшить коэффициент сухого трения в системе «ВТЗ-1 - СЧ20» до 0,1.

Анотація. У роботі досліджено структуру та властивості покриттів на титанових сплавах ПТ-3В і ВТ3-1, сформованих в електролітах різних типів (з додаванням КОН, NaAlO2, NaОН, (NaPO3)6, Na2SiO3) в анодно-катодному режимі методом мікродугового оксидування (МДО). Продемонстровано, что досягти високої твердості 9000-11000 МПа можливо за умови використання алюмінату натрію (NaAlO2) як складової електроліту. Фазовий склад такого покриття містить анатаз, рутил і титанат алюмінію. Використання МДО-оброблення титанових сплавів дозволяє зменшити коефіцієнт сухого тертя в системі «ВТЗ-1-СЧ20» до 0,1.