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

Research on the properties of Co-TiC and Ni-TiC HiP-sintered alloys

Three types of sintered alloys were fabricated based on cobalt, nickel and high-temperature alloy ZhS32-VI matrix with titanium carbide strengthening phase. TiC content was in a range of 30–50 vol. %. The melting temperatures of alloys are higher than 1320°C, and they may undergo undamaged through all technological procedures together with turbine blades, including soldering and outgassing. DSC analyses indicates no additional thermal effects until melting, which confirms their structural stability. The examinations of microstructure revealed three types of constituents – TiC particles, matrix solid solution and blow outs – structural defects having negative effects on all the studied properties. It was found that heat resistance of nickel based sintered alloys at the temperature of 1100°C is superior as compared with the alloys based on cobalt and alloy ZhS32-VI. It has been established that wear resistance in conditions of fretting wear at temperatures of 20, 850, 950 and 1050°C of sintered alloy with ZhS32-VI matrix is mostly superior as compared with the other alloys. The properties of produced alloys allow to use them for manufacturing of components of friction couples operating in conditions of high temperature fretting wear, including protective pads of turbine blades top shrouds contact faces

Duplex Aging and Gas Nitriding Process as a Method of Surface Modification of Titanium Alloys for Aircraft Applications

This study discusses the effect of a duplex aging + nitriding process on the wear resistance of an aged double-phase titanium alloy, BT22. Nitriding was applied simultaneously with the heat treatment of the alloy, which is advantageous over the conventional heat and surface treatment methods applied to titanium alloys. According to the results, the thickness of the case depth of the nitrided samples was 40–50 μm. Moreover, nitrogen was uniformly dispersed in the substrate, which was indicated by the hardness tests. The average microhardness of the substrate material was 300 HV0.01, while the hardness of the top layer was 1190 HV0.01, which is an almost four-fold increase. The applied duplex treatment substantially affected the wear performance of the tested alloy. For the untreated alloy, the maximum coefficient of friction was 0.8, while in the surface-modified sample, the maximum fluctuations reached 0.6. The abrasive wear process was dominant in the nitrided samples, while delamination and adhesive wear were observed for the untreated specimens. The nitrided alloy exhibited double the wear resistance of the untreated samples. The proposed treatment does not require additional time or energy consumption, providing a substantial technological advantage over conventional methods. Though the alpha case reduces the mechanical performance of titanium, the nitriding of only the component sections intended to withstand friction will have a positive effect

Duplex Aging and Gas Nitriding Process as a Method of Surface Modification of Titanium Alloys for Aircraft Applications

This study discusses the effect of a duplex aging + nitriding process on the wear resistance of an aged double-phase titanium alloy, BT22. Nitriding was applied simultaneously with the heat treatment of the alloy, which is advantageous over the conventional heat and surface treatment methods applied to titanium alloys. According to the results, the thickness of the case depth of the nitrided samples was 40–50 μm. Moreover, nitrogen was uniformly dispersed in the substrate, which was indicated by the hardness tests. The average microhardness of the substrate material was 300 HV0.01, while the hardness of the top layer was 1190 HV0.01, which is an almost four-fold increase. The applied duplex treatment substantially affected the wear performance of the tested alloy. For the untreated alloy, the maximum coefficient of friction was 0.8, while in the surface-modified sample, the maximum fluctuations reached 0.6. The abrasive wear process was dominant in the nitrided samples, while delamination and adhesive wear were observed for the untreated specimens. The nitrided alloy exhibited double the wear resistance of the untreated samples. The proposed treatment does not require additional time or energy consumption, providing a substantial technological advantage over conventional methods. Though the alpha case reduces the mechanical performance of titanium, the nitriding of only the component sections intended to withstand friction will have a positive effect

Fretting-Wear Mechanism of Textured Surfaces

The wear mechanism of textured dimpled in conditions of lubricated fretting-wear is established, which, in contrast to others, takes into account possibility of removing deterioration products out of tribo-contact areas into dimples, preventing their action as abrasive material. Selection of optimal structural parameters of selectively dimpled areas allows to reduce duration of tribological couple running-in time. Depending on texture type, friction coefficient was reduced from 0.27 (for untreated furface) to 0.18, and wear loss – from 7.8 ×10–3g to 3.3 ×10–3g

Теоретичні основи та технології нанесення зносостійких евтектичних покриттів

In this work we propose a new view to natural composite materials - multicomponent eutectic alloys, which may be used for broad variety of applications - manufacturing and recovery of turbine blades, stator vanes, metallurgical furnaces, quick closing equipment, cutting tools etc. These wear resistant materials may be used for manufacturing or modification of heavy duty components, so significant part of current work is devoted to overview and development of efficient coating deposition technologies - plasma and gas spray, laser alloying and surface engineering. We also evaluate the effects of deposition processes parameters on microstructures, mechanical properties and wear resistance of coatings being investigated

Теоретичні основи та технології нанесення зносостійких евтектичних покриттів

In this work we propose a new view to natural composite materials - multicomponent eutectic alloys, which may be used for broad variety of applications - manufacturing and recovery of turbine blades, stator vanes, metallurgical furnaces, quick closing equipment, cutting tools etc. These wear resistant materials may be used for manufacturing or modification of heavy duty components, so significant part of current work is devoted to overview and development of efficient coating deposition technologies - plasma and gas spray, laser alloying and surface engineering. We also evaluate the effects of deposition processes parameters on microstructures, mechanical properties and wear resistance of coatings being investigated

Improving the Wear Resistance of Heavy-duty Elements in Tribomechanical Systems by A Combined Laser-thermochemical Processing Method

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 significantl