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

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

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

Evaluation of Wear Resistance of Functional Composite Polymeric Materials and Durability of Metal-Polymer Bearings

A method of tribological testing of models with such sliding friction using a simple pin-on-disc mechanism was presented. Wear resistance indicators of unfilled polyamides PA6, PA66 and composites based on polyamide PA6+30GF, PA6+30CF, PA6+MoS2, PA6 and oil coupled with steel C45 are determined. They, as polymeric materials with the property of self-lubrication, they are often used in metal-polymer dry friction bearings. Based on them, wear resistance characteristics of these polymeric materials at sliding friction are established. They are used as basic parameters for developed by authors mathematical model of material wear kinetics at sliding friction and analytical research method of metal-polymer sliding bearings research. For comparative assessment of wear resistance of the investigated polymeric materials, their wear resistance diagrams are constructed. Thef show the functional dependence of wear resistance on specific friction forces. It is proved that the wear resistance of materials nonlinearly depends on specific pressure, i.e., the specific friction forces. Qualitative and quantitative influence of the type and structure of fillers (which improve the tribological properties of the base polymer PA6) on their wear resistance has been established. The forecast estimation of durability of metal polymer bearings made of the specified polyamides by the author's method of calculation taking into account their various wear resistance, characteristics of elasticity and conditions of dry friction is carried out. The research results are presented graphically, which facilitates their understanding and analyses

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

Microstructure and Friction Response of a Novel Eutectic Alloy Based on the Fe-C-Mn-B System

This paper focuses on the microstructure and tribological properties of novel hardfacing alloy based on Fe-C-Mn-B doped with Ni, Cr, and Si. The 4 mm-thick coating was deposited on the AISI 1045 carbon steel by the MIG-welding method using flux-cored wires in three passes. The transition zone thickness between the weld layers was ~80 μm, and the width of the substrate-coating interface was 5–10 μm. The following coating constituents were detected: coarser elongated M2B borides, finer particles of Cr7C3 carbides, and an Fe-based matrix consisting of ferrite and austenite. The nanohardness of the matrix was ~5–6 GPa, carbides ~16–19 GPa, and borides 22–23 GPa. A high cooling rate during coating fabrication leads to the formation of a fine mesh of M7C3 carbides; borides grow in the direction of heat removal, from the substrate to the friction surface, while in the transition zone, carbides become coarser. The dry sliding friction tests using a tribometer in PoD configuration were carried out at contact pressure 4, 7, 10, and 15 MPa against the AISI 1045 carbon steel (water-quenched and low-tempered, 50–52 HRC). The leading wear phenomenon at 4 and 7 MPa is fatigue, and at 10 and 15 MPa it is oxidation and delamination

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

Wear Resistance of Spark Ignition Engine Piston Rings in Hydrogen-Containing Environments

We describe the external and internal hydrogen interaction on contacting surfaces in the “cylinder–piston rings” friction coupling. Under the influence of high temperatures and pressure, the oil in the combustion chamber at a temperature up to 1473 K decomposes and forms small amounts of water. External hydrogen (H2) is subsequently formed. Hydrogen removal from the piston rings reduces the heterogeneity of the structure, residual stresses, and uneven physical and chemical properties of the near-surface layers, which reduces the stress concentration and, as a consequence, results in an improvement in the performance characteristics of the surface layers of the friction couple “cylinder-piston rings” of the spark ignition engine