Wear application of co-tic cemented carbides for gas turbines

The work offers a solution of urgent theoretical and practical problem of increase of wear resistance of GTE blades top shrouds contact faces. Implementation of current research results may increase service life of turbines. For –TiC cemented carbides manufacturing TiC-powders of grain size -20…+0.5 m were used. This provided them with combined micro and macro hardening. High strength of an alloy helps it to resist plastic deformations arising due to action of friction force. Accompanied by generating of friction induced surface structure with positive gradient of mechanical properties provides to Co-TiC cemented carbides perfect wear resistance at elevated and high temperature operatio

Improvement of the quality of TiC-Co system plasma coating by laser treatment

The paper considers the possibility to improve the quality of a plasma coating by means of a laser treatment in the melting and thermal cycling modes. This method provides stronger adhesion of a coating to its base material as well as higher wear resistance. The regularities of the laser treatment in the melting and thermal cycling modes are determined, and a connection between the technological parameters and the quality characteristics is shown

System analysis of the properties of discrete and oriented structure surfaces

A complex study of the properties and characteristics of discrete structure surfaces with mechanically formed dimples has been carried out. It is shown that the combination of scientific research on friction and wear processes in different scientific and engineering areas, such as mathematical statistics, mechanics of contact, physics of surfaces and magnetism and hydrodynamics, provides a deeper explanation of the processes that take place on discrete surfaces of contact elements

Features of transition modes of friction surfaces with partially regular microrelief

Textured surfaces with partially regular micro relief (PRMR) are reported to be an effective means to control lublication. It was found they are good wear debris trap and suppliers of lubricant directly to the actual friction area. Their tribological properties depend on the clearance between mating surfaces, relative slip speed, direction of motion. These parameters change the lubrication regime, and vice versa changing geometry of PRMR it is possible to predict and control lubrication regime for given conditions. Application of micro textured surface is prospective for high precision sliding units – valve slides of oil and hydraulic systems, faces of gear pump gears, ring-to-cylinder interface of aircraft reciprocating engines etc. providing high service life. On other side, changing texture parameters it is possible to stop the leakage of fluid through the gap, what may be efficiently utilized in aircraft non-contacting mechanical (hydrodynamic and hydrostatic) seals of gas compressors and gear mechanisms. This paper discloses some peculiarities of transition lubrication regimes for textured surfaces in lubricated contact

Підвищення зносостійкості важконавантажених деталей трибомеханічних систем методом комбінованого лазерно-хіміко-термічного оброблення

This paper reports an analysis of the state of tribological support in the aviation industry. The use of surface strengthening technologies to extend the resource of friction node parts has been prioritized. Modern combined technologies of nitriding and laser treatment of steel surfaces have been reviewed. The mechanism has been elucidated that damages steel 30H2NVFA in the jackscrew actuator of transport aircraft flaps, which occurs due to insufficient surface hardness of the material after a generally accepted heat treatment. Auger electron spectroscopy analysis revealed a high concentration of oxygen on the surface: up to 41.4 at. %; the friction surface carbonation has been detected, especially significant at the surface of the pitting damage. A comprehensive technology of surface strengthening by nitriding+laser selective hardening has been suggested. The radiation power was 1 KW, the diameter of the focus spot was 2.5 mm, and the pitch between the focus spot centers was 2.5 mm. The total area of laser processing was 70 %. The steel temperature exceeded Ас3 and corresponded to the hardening temperature range. The depth of the nitrided layer increased to 400 µm, the maximum hardness on the surface was 1,350–1,380 HV0.2. The formation of a solid nitrided layer with a thickness of 200‒250 µm was observed, as well as a transition zone composed of column-shaped iron nitrides, which are introduced into the matrix material. As a result, a sharp gradient in the mechanical properties disappears. The tests confirmed that the wear resistance of the comprehensively treated surface was 2.1 times higher under dry friction conditions, and 4.5 times higher when lubricated with the "Era" grease (RF), compared with the 30H2NVFA steel nitrided by the conventional technology. In addition, there was no fragile destruction of the surface; the interaction with oxygen reduced significantlyВыполнен анализ состояния трибологического обеспечения в авиационной отрасли. Установлена приоритетность использования технологий поверхностного упрочнения для повышения ресурса деталей узлов трения. Проведен обзор современных комбинированных технологий азотирования и лазерной обработки поверхностей сталей. Определен механизм повреждения стали 30Х2НВФА шарико-винтового подъемного механизма закрылков транспортного самолета, развивающийся вследствие недостаточной поверхностной твердости материала после общепринятой термической обработки. Оже-спектральным анализом установлена высокая концентрация кислорода на поверхности: до 41,4 % ат. Выявлено науглероживание поверхности трения, особенно значительное на поверхности питтингового повреждения. Предложена комплексная технология поверхностного упрочнения азотирование + лазерная дискретная закалка. Мощность излучения составила 1 кВт, диаметр пятна фокусировки – 2,5 мм и шаг между центрами пятен фокусировки 2,5 мм. Общая площадь обработки лазером составила 70 %. Температура стали превышала Ас3 и отвечала диапазону температур закалки. Глубина азотированного слоя увеличивается до 400 мкм, максимальная твердость на поверхности 1350-1380 HV0,2. Наблюдается образование сплошного азотированного слоя толщиной 200-250 мкм, и переходной зоны, состоящейиз нитридов железа столбчатой формы, внедренных в матричный материал. В результате исчезает резкий градиент механических свойств. Испытаниями подтверждено, что износостойкость комплексно обработанной поверхности в 2,1 раза более высокая в условиях сухого трения, и в4,5 раза– в условиях смазки консистентным маслом «Эра» (РФ) в сравнении с азотированной по общепринятой технологии сталью 30Х2НВФА. Кроме того, отсутствует хрупкое разрушение поверхности, значительно снижается взаимодействие с кислородомВиконано аналіз стану трибологічного забезпечення в авіаційній галузі. Встановлено пріоритетність використання технологій поверхневого зміцнення для підвищення ресурсу деталей вузлів тертя. Проведено огляд сучасних комбінованих технологій азотування і лазерної обробки поверхонь сталей. Визначено механізм пошкодження сталі 30Х2НВФА кульково-гвинтового підіймального механізму закрилків транспортного літака, що розвивається внаслідок недостатньої поверхневої твердості матеріалу після загально-прийнятої термічної обробки. Оже-спектральним аналізом встановлено високу концентрацію кисню на поверхні: до 41,4 % ат. Виявлено навуглецювання поверхні тертя, особливо значне на поверхні пітингового пошкодження. Запропоновано комплексну технологію поверхневого зміцнення азотування+лазерне дискретне гартування. Потужність випромінювання склала 1 КВт, діаметр плями фокусування – 2,5 мм і крок між центрами плям фокусування 2,5 мм. Загальна площа обробки лазером склала 70 %. Температура сталі перевищувала Ас3 івідповідала діапазону температур гартування. Глибина азотованого шару зростає до 400 мкм, максимальна твердість на поверхні 1350–1380 HV0,2. Спостерігається утворення суцільного азотованого шару товщиною 200–250 мкм, і перехідної зони, що складена з нітридів заліза стовпчастої форми, які проваджуються в матричний матеріал. Унаслідок цьогозникає різкий градієнт механічних властивостей.Випробуваннями підтверджено, що зносостійкість комплексно обробленої поверхні в 2,1 рази вища в умовах сухого тертя, і в 4,5 рази – в умовах мащення консистентним мастилом «Ера» (РФ) при порівнянні з азотованою за загальноприйнятою технологією сталлю 30Х2НВФА. Крім того, відсутнє крихке руйнування поверхні, значно знижується взаємодія з кисне

Wear-friction properties of friction pairs in disc-pad brakes

This paper reports data on the dynamic coefficient of friction and wear of materials of different types of friction pads and brake discs obtained from experimental research during braking under bench conditions. It was established that on the basis of the chemical composition of the materials of the friction pads with codes, in the temperature range of 100–450 °C with a step of 50 °C, the ratio of the maximum to the minimum wear of the disc varies from 6.0 to 10.0. The value of the disc wear ratio at 800 and 1000 brakings, respectively, in the temperature range of 100–250 °C and 100–450 °C was 7.6 and 14.0. This indicates that for pad materials of type A, B, C, and D under the second thermal regime, the linear wear of the working surfaces of the discs is greater than under the first thermal regime. And for the pad materials of type E and F, the wear of the discs was the same. This indicates that the use of traditional pads is characterized by a higher thermal tension of the disc brake friction pair; the absolute temperature values are in the unfavorable zone of 400–700 °C. That, in turn, could lead to both phase changes and thermal fatigue aging of materials and, as a result, to the deterioration of their tribological and thermophysical characteristics in operation. Thus, the implementation of the method of selecting pad components could improve the performance of disc brake devices of car

WEAR APPLICATION OF Co-TiC CEMENTED CARBIDES FOR GAS TURBINES

The work offers a solution of urgent theoretical and practical problem of increase of wear resistance of GTE blades top shrouds contact faces. Implementation of current research results may increase service life of turbines. For –TiC cemented carbides manufacturing TiC-powders of grain size -20…+0.5 m were used. This provided them with combined micro and macro hardening. High strength of an alloy helps it to resist plastic deformations arising due to action of friction force. Accompanied by generating of friction induced surface structure with positive gradient of mechanical properties provides to Co-TiC cemented carbides perfect wear resistance at elevated and high temperature operatio

FUNCTIONAL PLASMA-DEPOSITED COATINGS

The paper focuses on the problem of low adhesion of plasma sprayed coatings to the substrate. The subsequent laser treatment modes and their influence on the coatingsubstrate interface were studied. This allows to decrease the level of met-stability of the coating, thus decreasing its hardness down to 11–12 GPa on the surface and to about 9 GPa on depth of 400 µm. The redistribution of alloying elements through solid and liquid diffusion improves mechanical properties and rises the adhesion up to 450 MPa after remelting and up to 90–110 MPa after laser-aided thermal cycling. At the same time, remelting of coating helps to decrease its porosity down to 1%. The obtained complex of properties also allows to improve wear resistance of coatings and to decrease friction factor

THE MECHANISM OF FRICTION BETWEEN SURFACES WITH REGULAR MICRO GROOVES UNDER BOUNDARY LUBRICATION

The results of researches related to the influence of partially regular microrelief parameters on the adhesion component of the friction factor under boundary lubrication have been given. A special ring-on tape test rig is proposed in order to avoid errors during running-in process. Special technique is used to form sinusoidal microgrooves what helped to create a partially regular microrelief on the surface with controlled contour and nominal contact areas. Fatigue and deformation components of wear process are considered. We proved that microtexturing with proposed parameters decreases the adhesion component of friction and reduces the probability of microwelding. It has been shown that under boundary friction micro grooves are effective on precision surfaces with low roughness when lack of film and probability of seizure appear

Experimental Estimation of Wear Resistance of Polyamide Composites, Reinforced By Carbon and Glass Fibres Used in Metal-Polymer Gearings

The method of model triboexperimental studies to determine the basic mathematical model parameters of materials wear resistance at sliding friction is considered. The quantitative relative experimental characteristics of wear resistance of glass fibre and carbon fibre reinforced polyamide used in metal-polymer gear couple have been determined. Wear resistance functions of these functional polymeric composites have been established as the basic ones in the tribokinetic mathematical model of material wear for sliding friction conditions. Also, according to the conducted researches, wear resistance diagrams were constructed. They may be used as graphical indicators of wear resistance in the required range of specific friction forces. The dependences that connect the characteristic functions of wear resistance of these materials (obtained by the developed mathematical tribokinetic wear model) with linear wear and gearing service life are presented