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A comparative study of wear resistance, hardness and elastic modulus in samples of VT6 titanium alloy with a mineral coating created using low-temperature technological operations (local heating up to 80°C) and without coating was performed. The hardness and elastic modulus in nanoindentation mode were measured by applying a series of indentations with various maximum loads. The load was selected in a way that penetration depth of the tip into the material ranged from 500 nm to 4 μm with an estimated thickness of the modified layer of about 10 μm. The creation of a mineral layer increased the hardness of the surface of the titanium alloy sample by 45 -70 % and also caused a 2 -3 times increase of the roughness parameters of samples. Taking into account the specific features of measuring physical and mechanical properties of thin modified layers, wear resistance was measured using the method of multi-cycle friction with a sapphire sphere, while controlling the clamping force and deepness of the tip penetration into the sample. Wear resistance of the surface of the sample modified by minerals increased by 4 -5 times as compared to the wear resistance of the surface of the VT6 titanium alloy without a modification. By authors' opinion, the results of the studies reveal big potentials of using metal parts from titanium and titanium alloys with mineral coatings in various devices and mechanical assemblies. Проведено сравнительное исследование износостойкости, твердости и модуля упругости образцов из титаново-го сплава ВТ6 с минеральным покрытием, созданным при использовании низкотемпературных технологических операций (с локальным нагревом до 80°С), и без покрытия. Измерения твердости и модуля упругости в режиме наноиндентирования были проведены путем нанесения серии уколов с различной максимальной нагрузкой. Нагруз-ка подбиралась таким образом, чтобы глубина внедрения наконечника в материал составляла от 500 нм до 4 мкм при оценочной толщине модифицированного слоя около 10 мкм. Создание минерального слоя увеличило твердость поверхности образца из титанового сплава на 45 -70 %, а также увеличило параметры шероховатости образцов в 2 -3 раза. Корректность измерения определяется тем, что на малых глубинах влияние подложки на измеряемые величины мала, и поэтому ею можно было пренебречь. Разброс данных сопоставим с измеряемыми величинами, что, возможно, связано с относительно большой шероховатостью образцов. Учитывая особенности измерения фи-зико-механических свойств тонких модифицированных слоев, измерение износостойкости было выполнено мето-дом многоциклового трения сапфировой сферой с контролем силы прижима и углубления наконечника в образец. Использование такой системы измерения особенно важно при испытании тонких слоев, когда толщина слоя со-поставима с параметрами шероховатости поверхности. Износостойкость поверхности образца, модифицирован-ной минералами, увеличилась в 4 -5 раз по сравнению с износостойкостью поверхности титанового сплава ВТ6 без модификации. По мнению авторов, результаты исследования открывают бол...

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The work investigates some tribological parameters of the surfaces of friction pairs made of steel, with mineral layers. A comparative study of the friction coefficient of 18CrNiMo7-6 steel specimens with and without a mineral coating is performed. The lowest friction coefficient value was achieved for samples with mineral coating, without HFC hard surfacing before creating a mineral layer, and it was approximately 15% lower in comparison with the samples with HFC hard surfacing, but without mineral coating. The friction coefficient in the temperature range of 30…140 0 С, with constant displacement speed of samples with mineral coatings is practically unchanged for every sample type, the variation range does not exceed 0.02, as contrasted with the friction coefficient of the samples with hard surfacing, but without mineral coating. The value of the coefficient of volumetric wear of an aluminum oxide toroid during rotation with disks with some types of mineral coatings was at the level of detection limit (less than 1.2x10-9 mm 3 /Nm), which is significantly less than the coefficient of volume wear of a toroid during rotation with disks without coating (4-7)х10-8 mm 3 /Nm.

IntroductionThe core indicators of the quality of machine's parts, assemblies and mechanisms are reliability and lifespan, which are greatly defined by the properties of the surface layers of parts and junctions: wear resistance, corrosion resistance, friction rate, contact rigidity, seating stability, connection tightness. The reason for a short lifespan of parts and other structural components may be significantly associated with tear-and-wear and corrosive deterioration of their surface layers. To eliminate or slow down the processes taking place on the border between metal and environment, which have a negative effect on the operability of materials, various types of surface treatment are used. Besides multiple methods involving coatings, films and protective layers, there is a rapidly developing modern technology of changing physical and chemical properties of surface layers of metal parts by means of modification. In particular, industrial application of natural minerals for hardening surface layers of structural materials is finding its niche, due to the effects, combination of which leads to enhanced wear resistance, anti-friction, anti-corrosion and other specific properties of a friction pair.