Oleksandr Tisov - Academia.edu (original) (raw)

Papers by Oleksandr Tisov

Materials

This paper studies the microstructure, phase composition and tribological response of BT22 bimoda... more This paper studies the microstructure, phase composition and tribological response of BT22 bimodal titanium alloy samples, which were selectively laser-processed before nitriding. Laser power was selected to obtain a maximum temperature just a little above the α↔β transus point. This allows for the formation of a nano-fine cell-type microstructure. The average grain size of the nitrided layer obtained in this study was 300–400 nm, and 30–100 nm for some smaller cells. The width of the “microchannels” between some of them was 2–5 nm. This microstructure was detected on both the intact surface and the wear track. XRD tests proved the prevailing formation of Ti2N. The thickness of the nitride layer was 15–20 μm between the laser spots, and 50 μm below them, with a maximum surface hardness of 1190 HV0.01. Microstructure analyses revealed nitrogen diffusion along the grain boundaries. Tribological studies were performed using a PoD tribometer in dry sliding conditions, with a counterpart...

Materials

This paper focuses on the microstructure and tribological properties of novel hardfacing alloy ba... more 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 carri...

METALLOFIZIKA I NOVEISHIE TEKHNOLOGII

Проаналізовано процеси фазової взаємодії, що відбуваються під час високошвидкісного плазмово-дуго... more Проаналізовано процеси фазової взаємодії, що відбуваються під час високошвидкісного плазмово-дугового напорошування (ПДН) між сталевою оболонкою і порошковим наповнювачем дроту (70B 4 C + 20(Cr, Fe) 7 C 3 + + 10Al % мас.). Встановлено спрямованість термодинамічних реакцій між компонентами дроту з утворенням нових фаз (бороцементиту, бориду заліза) із застосуванням методу диференційного термічного аналізу. Нанесення покриттів проводили за допомогою установки PLAZER 30PL-W, розробленої в Інституті електрозварювання імені Є. О. Патона, в середовищі інертного газу арґону. Дослідження фазового складу вихідних матеріялів і одержаних покриттів виконували за допомогою дифрактометра ДРОН-УМ1. Диференційний термічний аналіз проводили за допомогою установки ВДТА-8М в середовищі гелію. Мікроструктуру покриттів про

Powder Metallurgy and Metal Ceramics

The use of powder-cored wires as electrodes for electrospark deposition (ESD) of coatings onto qu... more The use of powder-cored wires as electrodes for electrospark deposition (ESD) of coatings onto quenched and low-tempered steel 45 was studied. An industrial PP-Np-PD80Kh20R3T powder-cored wire (PW) and a combined powder-cored wire with an MPG-7 graphite addition (PWG) were applied. The mechanical characteristics peculiar to the surface layer of electrospark-deposited coatings produced from the powder-cored wires (hardness HV, friction coefficient μ, elastic strain energy Aelast, and plastic strain energy Aplast) were quantified. The indenter loading and kinetic indentation depth curves were plotted. Variations in penetration depth Pd and recovery depth Rd of the indenter in scratch tests of the ESD coatings produced from the powder-cored wires were illustrated. Characteristic changes in the mechanical characteristics at a preset indenter penetration depth and the microstructure of the ESD powder-cored coatings subjected to scratch tests were examined. The wear rate of the ESD coatings deposited with PW and PWG electrodes was established as a function of specific loading, sliding speed, and testing time. Variations in roughness of the friction surfaces and temperatures in the contact area in dry sliding friction conditions were studied. The PWG coating showed 24% higher hardness than the PW coating did and 10% lower friction coefficient determined by indentation. The roughness of the PWG coating increased by 10% when loading changed from 3 to 7 MPa. The PWG coating (pin-on-disk friction test) had 2.5 times higher wear resistance than the PW coating did, and the disk (counterface) had 28% lower wear. A slight increase of temperature in the tribological contact area was not found to soften the coating or substrate (quenched and low-tempered steel 45) but promoted regeneration of the protective oxide layer and favorably influenced the friction process. Both materials produced from the powder-cored wires (PW and PWG) exhibited normal mechanochemical wear in experimental conditions. The high wear resistance of the ESD coatings produced from the powder-cored wires in dry friction conditions indicated that they would be beneficial for strengthening and improving the life of various machine parts and mechanisms in industrial mechanical engineering.

Materials

In this study, we analyzed the quaternary Fe-C-Mn-B system to create new eutectic cast alloys for... more In this study, we analyzed the quaternary Fe-C-Mn-B system to create new eutectic cast alloys for coating deposition and additive manufacturing. Experimental samples were fabricated via the wire arc manufacturing method with argon shielding using Kemppi Pro 5200 Evolution equipment. Annealing was performed in a vacuum electric furnace at 1273 K for 350 h. For phase analyses, Jeol Superprobe 733 equipment was used. Metallographic and differential thermal analyses were used to reveal the eutectic structure of the samples. Examinations of the quaternary Fe-C-Mn-B system demonstrated that several eutectic alloys existed in the system. Four isothermal pseudo-ternary sections of the Fe-C-Mn-B system were studied: “Fe3B”-Fe3C-“Fe3Mn”; Fe2B-“Fe2C”-“Fe2Mn”; “Fe3B”-Fe3C-“Fe1.2Mn”; “Fe23B6”-“Fe23C6”-“Fe23Mn”. Broad eutectic concentrations enabled us to overcome parameter fluctuations during additive manufacturing. In each isothermal section, two dissimilar phase regions were determined: one wi...

Journal of Materials Science and Chemical Engineering

Advances in Science and Technology Research Journal, 2017

Вісник двигунобудування, 2012

Advances in Science and Technology Research Journal, 2022

Authors have produced new polymer-based composite material DK-6(PT) for substitution of Moglice (... more Authors have produced new polymer-based composite material DK-6(PT) for substitution of Moglice (Diamant) polymer. We manufactured and used sliding-friction test apparatus (pin-on-disc) capable of testing three specimens simultaneously, much reducing time for the test. The monitoring of the material curing process and the Shore hardness test indicate minor diff erence from reference material. Measurements were carried out during the curing period, since it is important to know change in this parameter over time. The wear test proved that DK-6(PT) composite in the long-time test has good wear resistance: over 80 km of the friction path, the wear loss of both materials is approximately the same. Furthermore, the friction factor of DK-6(PT) is 5–10% less than that of Moglice. Thus, the studied new polymeric composite may compete with well-known material Moglice and signifi cantly cut the expenses for reconditioning of worn slide ways of metal working equipment.

The work offers a solution of urgent theoretical and practical problem of increase of wear resist... more 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 operation INTRODUCTION. Developments in aerospace engineering were always accompanied by increase of fuel combustion temperature, thus improving fuel efficiency or increasing thrust of the engine (ref. 1). But it also increases loading of turbine elements, especially of rotor blades and decreases service life o...

Tribology in Industry, 2021

Eastern-European Journal of Enterprise Technologies, 2021

This paper reports an analysis of the state of tribological support in the aviation industry. The... more 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...

In this work we propose a new view to natural composite materials - multicomponent eutectic alloy... more 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

Metals, 2022

This study discusses the effect of a duplex aging + nitriding process on the wear resistance of a... more 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 delami...

Objectives to investigate non-equilibrium states of eutectics ....... 2.2. Impact of cooling rate... more Objectives to investigate non-equilibrium states of eutectics ....... 2.2. Impact of cooling rate on the crystallization mechanism of eutectics .. 2.3. The growth of rapidly cooled eutectics .

Advances in Science and Technology Research Journal

The wear mechanism of textured dimpled in conditions of lubricated fretting-wear is established, ... more 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 ×10-3 g to 3.3 ×10-3 g.

Acta Mechanica et Automatica

Three types of sintered alloys were fabricated based on cobalt, nickel and high-temperature alloy... more 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 o...

Aviation

Textured surfaces with partially regular micro relief (PRMR) are reported to be an effective mean... more 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 compr...

Textured surfaces with partially regular micro relief (PRMR) are reported to be an effective mean... more 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.

Materials

This paper studies the microstructure, phase composition and tribological response of BT22 bimoda... more This paper studies the microstructure, phase composition and tribological response of BT22 bimodal titanium alloy samples, which were selectively laser-processed before nitriding. Laser power was selected to obtain a maximum temperature just a little above the α↔β transus point. This allows for the formation of a nano-fine cell-type microstructure. The average grain size of the nitrided layer obtained in this study was 300–400 nm, and 30–100 nm for some smaller cells. The width of the “microchannels” between some of them was 2–5 nm. This microstructure was detected on both the intact surface and the wear track. XRD tests proved the prevailing formation of Ti2N. The thickness of the nitride layer was 15–20 μm between the laser spots, and 50 μm below them, with a maximum surface hardness of 1190 HV0.01. Microstructure analyses revealed nitrogen diffusion along the grain boundaries. Tribological studies were performed using a PoD tribometer in dry sliding conditions, with a counterpart...

Materials

This paper focuses on the microstructure and tribological properties of novel hardfacing alloy ba... more 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 carri...

METALLOFIZIKA I NOVEISHIE TEKHNOLOGII

Проаналізовано процеси фазової взаємодії, що відбуваються під час високошвидкісного плазмово-дуго... more Проаналізовано процеси фазової взаємодії, що відбуваються під час високошвидкісного плазмово-дугового напорошування (ПДН) між сталевою оболонкою і порошковим наповнювачем дроту (70B 4 C + 20(Cr, Fe) 7 C 3 + + 10Al % мас.). Встановлено спрямованість термодинамічних реакцій між компонентами дроту з утворенням нових фаз (бороцементиту, бориду заліза) із застосуванням методу диференційного термічного аналізу. Нанесення покриттів проводили за допомогою установки PLAZER 30PL-W, розробленої в Інституті електрозварювання імені Є. О. Патона, в середовищі інертного газу арґону. Дослідження фазового складу вихідних матеріялів і одержаних покриттів виконували за допомогою дифрактометра ДРОН-УМ1. Диференційний термічний аналіз проводили за допомогою установки ВДТА-8М в середовищі гелію. Мікроструктуру покриттів про

Powder Metallurgy and Metal Ceramics

The use of powder-cored wires as electrodes for electrospark deposition (ESD) of coatings onto qu... more The use of powder-cored wires as electrodes for electrospark deposition (ESD) of coatings onto quenched and low-tempered steel 45 was studied. An industrial PP-Np-PD80Kh20R3T powder-cored wire (PW) and a combined powder-cored wire with an MPG-7 graphite addition (PWG) were applied. The mechanical characteristics peculiar to the surface layer of electrospark-deposited coatings produced from the powder-cored wires (hardness HV, friction coefficient μ, elastic strain energy Aelast, and plastic strain energy Aplast) were quantified. The indenter loading and kinetic indentation depth curves were plotted. Variations in penetration depth Pd and recovery depth Rd of the indenter in scratch tests of the ESD coatings produced from the powder-cored wires were illustrated. Characteristic changes in the mechanical characteristics at a preset indenter penetration depth and the microstructure of the ESD powder-cored coatings subjected to scratch tests were examined. The wear rate of the ESD coatings deposited with PW and PWG electrodes was established as a function of specific loading, sliding speed, and testing time. Variations in roughness of the friction surfaces and temperatures in the contact area in dry sliding friction conditions were studied. The PWG coating showed 24% higher hardness than the PW coating did and 10% lower friction coefficient determined by indentation. The roughness of the PWG coating increased by 10% when loading changed from 3 to 7 MPa. The PWG coating (pin-on-disk friction test) had 2.5 times higher wear resistance than the PW coating did, and the disk (counterface) had 28% lower wear. A slight increase of temperature in the tribological contact area was not found to soften the coating or substrate (quenched and low-tempered steel 45) but promoted regeneration of the protective oxide layer and favorably influenced the friction process. Both materials produced from the powder-cored wires (PW and PWG) exhibited normal mechanochemical wear in experimental conditions. The high wear resistance of the ESD coatings produced from the powder-cored wires in dry friction conditions indicated that they would be beneficial for strengthening and improving the life of various machine parts and mechanisms in industrial mechanical engineering.

Materials

In this study, we analyzed the quaternary Fe-C-Mn-B system to create new eutectic cast alloys for... more In this study, we analyzed the quaternary Fe-C-Mn-B system to create new eutectic cast alloys for coating deposition and additive manufacturing. Experimental samples were fabricated via the wire arc manufacturing method with argon shielding using Kemppi Pro 5200 Evolution equipment. Annealing was performed in a vacuum electric furnace at 1273 K for 350 h. For phase analyses, Jeol Superprobe 733 equipment was used. Metallographic and differential thermal analyses were used to reveal the eutectic structure of the samples. Examinations of the quaternary Fe-C-Mn-B system demonstrated that several eutectic alloys existed in the system. Four isothermal pseudo-ternary sections of the Fe-C-Mn-B system were studied: “Fe3B”-Fe3C-“Fe3Mn”; Fe2B-“Fe2C”-“Fe2Mn”; “Fe3B”-Fe3C-“Fe1.2Mn”; “Fe23B6”-“Fe23C6”-“Fe23Mn”. Broad eutectic concentrations enabled us to overcome parameter fluctuations during additive manufacturing. In each isothermal section, two dissimilar phase regions were determined: one wi...

Journal of Materials Science and Chemical Engineering

Advances in Science and Technology Research Journal, 2017

Вісник двигунобудування, 2012

Advances in Science and Technology Research Journal, 2022

Authors have produced new polymer-based composite material DK-6(PT) for substitution of Moglice (... more Authors have produced new polymer-based composite material DK-6(PT) for substitution of Moglice (Diamant) polymer. We manufactured and used sliding-friction test apparatus (pin-on-disc) capable of testing three specimens simultaneously, much reducing time for the test. The monitoring of the material curing process and the Shore hardness test indicate minor diff erence from reference material. Measurements were carried out during the curing period, since it is important to know change in this parameter over time. The wear test proved that DK-6(PT) composite in the long-time test has good wear resistance: over 80 km of the friction path, the wear loss of both materials is approximately the same. Furthermore, the friction factor of DK-6(PT) is 5–10% less than that of Moglice. Thus, the studied new polymeric composite may compete with well-known material Moglice and signifi cantly cut the expenses for reconditioning of worn slide ways of metal working equipment.

The work offers a solution of urgent theoretical and practical problem of increase of wear resist... more 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 operation INTRODUCTION. Developments in aerospace engineering were always accompanied by increase of fuel combustion temperature, thus improving fuel efficiency or increasing thrust of the engine (ref. 1). But it also increases loading of turbine elements, especially of rotor blades and decreases service life o...

Tribology in Industry, 2021

Eastern-European Journal of Enterprise Technologies, 2021

This paper reports an analysis of the state of tribological support in the aviation industry. The... more 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...

In this work we propose a new view to natural composite materials - multicomponent eutectic alloy... more 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

Metals, 2022

This study discusses the effect of a duplex aging + nitriding process on the wear resistance of a... more 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 delami...

Objectives to investigate non-equilibrium states of eutectics ....... 2.2. Impact of cooling rate... more Objectives to investigate non-equilibrium states of eutectics ....... 2.2. Impact of cooling rate on the crystallization mechanism of eutectics .. 2.3. The growth of rapidly cooled eutectics .

Advances in Science and Technology Research Journal

The wear mechanism of textured dimpled in conditions of lubricated fretting-wear is established, ... more 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 ×10-3 g to 3.3 ×10-3 g.

Acta Mechanica et Automatica

Three types of sintered alloys were fabricated based on cobalt, nickel and high-temperature alloy... more 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 o...

Aviation

Textured surfaces with partially regular micro relief (PRMR) are reported to be an effective mean... more 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 compr...

Textured surfaces with partially regular micro relief (PRMR) are reported to be an effective mean... more 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.