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AbstractIn this work, an improved 1D microslip model at the frictional joint interface considering the effect of surface topography is developed, which is further used to evaluate the fretting wear performance of the joint structure. The rough surface contact of the joint interface is characterized by the micro-asperity Greenwood and Williamson statistical contact model (GW model). A thin layer with elastic tangential stiffness, exhibiting equivalent properties to accord with the micro-asperity contact of the rough interface, is supposed to connect with the two components comprising the joint interface. The nonuniform clamping pressure distribution is considered and the resulted stick-slip transitions along the interface are derived using the continuum elastic beam model. The tangential stiffness of micro-asperities for rough surface contact is derived and incorporated into the continuum beam model to obtain the relative slip displacement along the interface. Fretting wear depth resulted from the cyclic microslip at the interface is evaluated based on the relative sliding distance and the Archard wear model. Results show that the minimum tangential force causing microslip motion increases with surface roughness and preload. The slip length increases with the tangential force whilst decreases with the increased surface roughness. The wear depth progressively increases from stuck region to slip region, and decreases as the surface roughness and preload increase. Experimental validation is performed and excellent agreement is observed between model predictions and experimental results. The developed model provides important new insights into the prediction of fretting wear and loosening behavior of the bolted joints. [ABSTRACT FROM AUTHOR]

Fretting degrades the inboard inner ring and the backing ring contact surfaces of axle journal roller bearings used in railway applications. This study attempts to prevent fretting wear between them as well as fretting wear particles from entering the axle bearing interior without introducing new bearing components. It has been reported that coating metallic surfaces with bonded solid film lubricants improves lubricity and wear resistance while reducing fretting wear. To evaluate the impact on fretting wear prevention, a full-size railway axle bearing that was coated a backing ring side face with a bonded solid film lubricant was rotated. The findings demonstrate that applying the bonded solid film lubricant to the backing ring side face does not prevent the axle bearings from fretting. The surface temperature probably exceeds the heat-resistant temperature of the solid film lubricant because of the fretting friction. [ABSTRACT FROM AUTHOR]

The TC4 alloy has become an ideal material for marine engineering due to its excellent corrosion resistance, high specific strength and light weight in seawater. However, components made from TC4 alloys often come into contact with parts such as propellers and turbine engine blades, leading to severe fretting wear during operation and significantly reducing their service life. In this study, the untreated TC4 alloy samples were used as the control group, and the samples after 240 min of surface mechanical attrition treatment (SMAT) were selected to investigate the fretting wear behavior under different load conditions in artificial seawater environment. The results show that the friction coefficient of TC4 alloy remains relatively unaffected by load variations, both before and after SMAT treatment. With the increase of load, the fretting regime gradually changed from gross slip to partial slip, and the wear depth, volume and wear rate increased. Under the same load, the wear volume of TC4 alloy after SMAT treatment is significantly reduced, indicating that its wear performance has been improved. [ABSTRACT FROM AUTHOR]

Heavy-duty gas turbine is the core equipment in energy and electricity systems. In the compressor of a heavy-duty gas turbine, the forces and torques are usually transmitted by the friction force of the annular flat contact interfaces between two adjacent discs. Aimed at the annular flat connection structure of the combined rotor in heavy-duty gas turbine, the distribution of fretting characteristics on the annular flat is analyzed. The wear depth was calculated on the contact interface based on the modified Archard's wear theory and finite element method. On the annular flat, the time-varying distributions of fretting characteristics with the progress of wear are investigated. The increase of fretting cycles increases the wear depth of the annular flat. Moreover, the effects of load conditions and disc geometrical parameters on the fretting characteristics are studied. The increase of tie rod preload force and transmitted torque will intensify the fretting wear on the annular flat. In addition, the decrease of the distance between the tie rod and the annular flat and the decrease of the width of the annular flat will exacerbate the fretting wear on the annular flat. A fretting wear experiment is conducted to verify the finite element model. The experimental results show the fitting curve of wear depth decreases from the inner radius to the outer radius, which aligns with the results obtained from the finite element simulation. Ultimately, the research of this paper will provide a reference for the design and engineering application of the annular flat contact interfaces. [ABSTRACT FROM AUTHOR]

The fuel rod casing tube is a crucial component in pressurized water reactor (PWR) nuclear power plants. Flow-induced vibrations in the circulating water can result in complex alternating fretting wear between the casing tube and the positioning lattice frame. Existing research on fretting wear has primarily focused on unidirectional wear, with limited investigation into composite fretting wear under complex working conditions. This study conducted impact and tangential composite fretting wear tests on Zr-4 alloy tubes under varying constant and random impact loads to examine fretting wear behavior. The findings show that the peak friction coefficients in the impact and tangential composite fretting wear tests were consistent across the three constant load conditions, with higher peak friction coefficients observed under random load conditions and a longer time required to reach these peaks during micromotion tests. Comparative analysis revealed that random impact and tangential composite fretting wear caused the most severe damage. Under constant load conditions, wear damage became more severe with increasing load, transitioning from oxidized and adhesive wear to a peeling layer as the load intensified in the impact and tangential composite fretting wear tests. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article proposes a model of predicting the fretting wear lifetime of a low-friction coating. The proposed model incorporates multiple factors that influence the fretting wear damage of coatings: the imposed contact load, imposed average velocity, coating hardness, and initial surface roughness of counterparts. The fretting wear lifetime of coatings, defined as the number of cycles critical to friction coefficient evolution, was collected from the literature. For the purpose of identifying parameters in the model, experimental fretting wear lifetime data were analyzed. The results show that the fretting wear lifetime of a coating can be described by an inverse power law regarding the contact load, imposed average velocity, and initial surface roughness of counterparts. In contrast, the fretting wear lifetime of a coating was observed to increase with increased coating hardness. It was observed that the exponents of the inverse power law varied with respect to the type of coating. The proposed fretting wear lifetime model enables the prediction of coating lifetime under various fretting conditions. [ABSTRACT FROM AUTHOR]

Double-glow low-temperature plasma carburization (LTPC) was utilized to prepare a carburized layer (PC) on a 316L austenitic stainless steel (ASS) surface, and the fretting wear behavior was evaluated at various temperatures and frequencies. The friction coefficient curves could be divided into running-in, wear, and stable stages. With increasing temperature, the wear mechanism of 316L ASS changed from adhesive and abrasive wear to adhesive wear, accompanied by plastic deformation, fatigue peeling, and oxidative wear. The carburized layer had an adhesive wear, plastic deformation, fatigue peeling, and oxidative wear mechanism. As the frequency increased, 316L ASS showed an adhesive wear, fatigue peeling, and oxidative wear mechanism. With increasing frequency, the wear mechanism of PC changed from abrasive and adhesive wear to abrasive wear, adhesive wear, and fatigue peeling, accompanied by oxidative wear. The carburized layer generally showed lower frictional energy dissipation coefficients and wear rates than 316L ASS. This work demonstrated that plasma carburization could improve the fretting wear stability and resistance of 316L ASS. The rise in frictional temperature, the tribo-chemical reaction time, and the evolution of debris collectively influenced the wear mechanisms and wear morphologies of 316L ASS before and after plasma carburization. This could provide theoretical support for the fretting damage behaviors of ball valves under severe service conditions. [ABSTRACT FROM AUTHOR]

A self-developed tube-to-tube contact fretting wear tester was used to conduct fretting wear tests on Zr-4 fuel rods in pressurized water reactors of nuclear power plants under three fretting wear modes (tangential, radial, and dual-motion fretting) with different normal loads [Fn = 15–25 (20), 30–50 (40), and 45–75 (60) N]. The test results show that the normal load and fretting wear mode have a significant effect on the fretting wear behaviors of Zr-4 alloy tube. Comparing the different fretting wear modes, the contact surface is almost coordinated by elastic deformation under the radial fretting wear mode, with the slightest damage; for tangential fretting wear mode, the damage mechanism is mainly fatigue wear and delamination; the most severe damage was observed under the dual-motion fretting wear mode, where the wear mechanism consisted of a combination of delamination, abrasive wear, adhesive wear, and oxidative wear. [ABSTRACT FROM AUTHOR]

The steam generator is subjected to the action of high temperature and high-pressure steam， and the flow induced vibration phenomenon of its heat transfer tube is caused by the secondary lateral flow. At the same time， the periodic loads cause fretting wear and fretting fatigue in the Inconel 690 alloy tube heat transfer tube and 403SS anti-vibration bar， which makes the heat transfer tube crack or even rupture and fail， and affects the safe operation of the nuclear power system. The friction and wear test of Inconel 690 alloy heat transfer tube and 403SS anti-vibration bar under different normal loads and displacement amplitudes was carried out by using fretting wear testing machine under normal temperature air and high-temperature air. The surface wear morphology and oxidation components of Inconel 690 alloy heat transfer tube were analyzed to reveal the wear failure mechanism of the heat transfer tube of the steam generator. The results show that with the increase of normal load at room temperature， debris accumulation and delamination appear on the surface of worn scars， and the degree of oxidation gradually intensifies. The fretting wear mechanism is mainly friction oxidation， abrasive wear， and delamination. Under the condition of high-temperature air， the peak friction force and the depth of worn scars increase， and the width of worn scars decrease. The plastic flow on the surface of the material is obvious， and the degree of oxidation and delamination deepens under the condition of high-temperature air. The fretting wear mechanism is mainly friction oxidation and delamination.

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The fretting wear behavior of H62 brass against GCr15 steel under prestressed conditions was studied using a self-developed fretting wear device in this study. The effects of normal loads, prestresses, fretting frequencies, and fretting movement amplitudes were studied. Simultaneously, the changes in the coefficient of friction, depth of the wear scar, surface morphologies of the wear scar, and wear mechanisms were analyzed. Experimental results showed that the coefficient of friction decreased as the normal loads and prestresses increased and increased as the fretting frequencies and fretting movement amplitudes increased. The depth of the wear scars clearly increased as the normal loads and prestresses increased and decreased as the fretting movement amplitudes increased. The oxygen contents slightly increased in the annular area of the wear scars. The main wear mechanisms of H62 brass against GCr15 under different fretting parameters used in this study were abrasive wear, adhesion wear, and local spalling. [ABSTRACT FROM AUTHOR]

Ti–Al–C–N protective coatings were prepared using laser cladding on the TC4 in this work. MAX phase is generated in situ in the coating. Moreover, as an in-situ autogenous reinforcing phase, MAX phase has good compatibility with the substrate and good bonding force, which is conducive to the full realization of the cladding performance. The results show that the amount of MAX phase increased with the proportion of ceramic phase in the composition design. Among them, the best coating performance is achieved when the component ratio is TiAl: TiN: TiC = 1:1:1. The coating shows the highest hardness of 712–950 HV, which was about twice the hardness of the substrate. It also shows the best resistance to fretting wear at both room temperature and 400 °C. The analysis of the wear mechanism reveals that twins are formed in C1 coatings during fretting wear at both room temperature and 400 °C. The twins not only can rapidly relax the local stress concentration and maintain the plasticity of the material, but also can promote the continuation of slip, and play an obvious strengthening effect without causing serious stress concentration. This work can provide the theoretical basis and data support for the functional-structural integration of protection design of components under actual working conditions. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The influence of electric current pulses passing between parts during fretting wear of titanium alloys is examined. A description of the test bench and a description of the test methodology are given. [ABSTRACT FROM AUTHOR]

Fretting wear damage of high-strength titanium fasteners has caused a large number of disastrous accidents. Traditionally, it is believed that both high strength and excellent ductility can reduce fretting wear damage. However, whether strength and ductility are contradictory or not and their appropriate matching strategy under the external applied normal stress (Fw) are still confusing problems. Here, by analyzing the subsurface-microstructure deformation mechanism of several samples containing various α precipitate features, for the first time, we design strategies to improve fretting damage resistance under different matching relation between Fw and the tensile strength of materials (Rm). It is found that when Fw is greater than Rm or Fw is nearly equivalent to Rm, the deformation mechanism mainly manifests as serious grain fragmentation of β and αGB constituents. Homogeneous deformation in large areas only reduces damage to a limited extent. It is crucial to improve the strength to resist cracking and wear, but it is of little significance to improve the ductility. However, when Fw is far less than Rm, coordinated deformation ability reflected by ductility plays a more important role. The deformation mechanism mainly manifests as localized deformation of β and αGB constituents (kinking induced by twinning and spheroidizing). A unique composite structure of nano-grained/lamellar layer and localized deformation transition layer reduces fretting damage by five times compared with a single nano-grained layer. Only when the strength is great enough, improving the plasticity can reduce wear. This study can provide a principle for designing fretting damage resistant alloys. [ABSTRACT FROM AUTHOR]

In this work, the behavior of Zr-1Nb-1Sn-0.1Fe fuel rods was studied by subjecting them to physical tests aimed at reproducing the occurrence of fretting. For that, heat treatments were carried out on the surfaces of the fuel rods at different temperatures to modify the microstructure (a-Zr to ß-Zr) and improve the mechanical properties. Mechanical tests and microstructural characterization confirmed the improvement in the mechanical properties and the modification of the alloy microstructure. The fretting tests were carried out in equipment designed to induce horizontal displacements to the fuel rods in relation to spacer grid. It was verified, through confocal microscopy, that the fretting wear mechanisms observed in the fuel rods include abrasion, adhesion, and plastic deformation, and that the increase in the heat treatment temperature decreases the mass loss, indicating a mild fretting wear regime. [ABSTRACT FROM AUTHOR]

This study investigates the capability of WC/C coatings to protect bearing bores against fretting wear when there is a lack of lubrication, a typical failure mechanism in bearings subjected to vibrations. Linear pin-on-disc and rotary oscillating block-on-ring tribological tests were carried out reproducing fretting conditions to evaluate the tribological performance and fretting resistance of the developed WC/C coating in comparison with those of the two common coatings currently employed to prevent this type of bearing failure, i.e. thin-dense chrome and fluoropolymer coatings. The friction forces generated under fretting conditions were evaluated, and a deep surface analysis of the tribosystems was carried out through different microscopic techniques in order to identify the wear mechanisms prevailing in each coating. Results suggested that WC/C coatings could be promising candidates to mitigate fretting damage, as they combine a low friction coefficient with good wear resistance. Furthermore, WC/C coatings constitute a more sustainable solution compared to the currently employed PTFE and chrome-based coatings, paving the way to a greener society. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fretting wear is a phenomenon occurring in many engineering objects, including push fit connections. In view of a large number of factors conducive to wear development, it is difficult to describe the mechanism of wear initiation and development. Therefore, various methods are sought to limit wear development. The use of a lubricant may be one of those ways. The aim of this article is to present the results of testing the influence of a lubricant medium on the development of fretting wear in interference fit connections. As a lubricant medium, MoS2 and Whitmore greases were used. For that purpose, wear tests were first conducted on the shaft/sleeve tribological kinematic pair, and then observations and laboratory measurements were performed. The observations demonstrated the presence of fretting wear traces on all tested samples, irrespective of the tribological kinematic pair being tested. The main kind of damage consisted of material build-ups which, during operation, become oxidised and, while moving along the connection, caused local abrasion and micropits. The best results in restricting the development of fretting wear were achieved with Whitmore grease. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The metallic plate is used for bone fixation in biomedical applications, which causes health risks to the patient by leaching ion elements due to the formation of micro-motion between the plate and screw. Currently, the polylactic acid is favoured for replacing metal alloys in temporary implants due to the biodegradable property. However, polylactic acid has low mechanical properties compared to metal alloys and is not preferred as a fixation device. Therefore, the polylactic acid was printed using FDM technique under both horizontal and vertical orientations to improve the mechanical properties. After printing, the samples were post-heat treated at 60℃ for 24 h (B1) and 70℃ for 12 h (B2). Later, compression and fretting wear tests were performed for the printed and post-heat-treated samples to estimate the compression strength and fretting wear. The results indicated that the post-heat-treated horizontal sample B2 obtained a higher compression yield strength of 80.15 ± 3.53 MPa compared to printed and post-treated sample B1. This value lies within the range of bone fixation device. Moreover, a low coefficient of friction (1.34 ± 0.23) was obtained for sample B2 due to the improvement of yield strength. The worn morphology showed that the formation of cracks and spalling was more for the printed and B1 sample compared to the B2 [ABSTRACT FROM AUTHOR]

The TC4 alloy has become an ideal material for marine engineering due to its excellent corrosion resistance, high specific strength and light weight in seawater. However, components made from TC4 alloys often come into contact with parts such as propellers and turbine engine blades, leading to severe fretting wear during operation and significantly reducing their service life. In this study, the untreated TC4 alloy samples were used as the control group, and the samples after 240 min of surface mechanical attrition treatment (SMAT) were selected to investigate the fretting wear behavior under different load conditions in artificial seawater environment. The results show that the friction coefficient of TC4 alloy remains relatively unaffected by load variations, both before and after SMAT treatment. With the increase of load, the fretting regime gradually changed from gross slip to partial slip, and the wear depth, volume and wear rate increased. Under the same load, the wear volume of TC4 alloy after SMAT treatment is significantly reduced, indicating that its wear performance has been improved.

Fretting wear is the main factor restricting the application of titanium alloy as compressor blades. Preparing a kind of high entropy alloy (HEA) coating is an effective way to improve the fretting wear resistance under high temperature conditions. Thus, in the present work, the FeCrAlMoxNby HEA coating was fabricated on a Ti-64 substrate by the laser cladding technology. The phase composition, microstructure and fretting wear resistance of the coating at high temperatures (200 °C, 300 °C and 400 °C) were investigated. It was demonstrated that the laser cladding FeCrAlMoxNby HEA coatings exhibited dense and uniform microstructures consisting of a BCC phase and a Laves phase (Cr2Nb). In addition, the changing trend of phase content of BCC and Laves phase is the same as the trend of atomic content of Mo and Nb respectively. The presence of the Laves phase increases the hardness of the coating. Due to its high hardness and the formation of a protective oxide layer, the coating demonstrated significantly superior resistance to high-temperature fretting wear compared to the substrate. The lowest wear rate is Mo0·5Nb0.5 coating at 300 °C, only 1.3 × 10−6 mm3/N·m. The current results provide a new method to protect titanium alloy's surface from fretting wear damage in high-temperature service environments.

This study investigates the fretting wear resistance of Inconel 718 fabricated by laser-powder bed fusion (L-PBF) based additive manufacturing (AM) process. A set of the L-PBF processed coupons were subjected to homogenization followed by double aging heat treatment cycles to achieve hardness comparable to wrought material. Material characterization using optical microscopy, scanning electron microscopy (SEM) and x-ray diffraction techniques revealed a fine grained and textured microstructure in AM as-built samples. Point contact (ball-on-flat) fretting wear tests conducted under ambient conditions showed that AM as-built samples had the least wear resistance with a wear coefficient of 15.64 × 10−9 MPa−1 and a higher average coefficient of friction (COF) of 0.75. The wear resistance of the AM samples was found to be improved after heat treatment with the reduced wear coefficient of 10.35 × 10−9 MPa−1 and COF ranged between 0.60 and 0.70. The fretting loops, COF plots and SEM analysis on worn surfaces show that when the applied normal load is low (1N), the operating regime is gross slip regime and the corresponding wear damage is abrasion for all samples. When the load increases to high level (3N), a combined wear mechanism of delamination, adhesion and abrasive wear operating under partial slip regime is predominant with a considerable amount of subsurface cracking. The effect of heat treatment is seen as beneficial in terms of reduction in wear, COF and sub-surface crack which is attributed to improved hardness. [ABSTRACT FROM AUTHOR]

Safety and reliability are the major challenges to face for the development and acceptance of hydrogen technology. It is therefore crucial to deeply study material compatibility, in particular for tribological components that are directly in contact with hydrogen. Some of the most critical parts are sealing materials that need increased safety requirements. In this study, the fretting behavior of several elastomer materials were evaluated against 316L stainless steel in an air and hydrogen environment up to 10 MPa. Several grades of cross-linked hydrogenated acrylonitrile butadiene (HNBR), acrylonitrile butadiene (NBR) and ethylene propylene diene monomer rubbers (EPDM) were investigated. Furthermore, aging experiments were conducted for 7 days under static conditions in 100 MPa of hydrogen followed by rapid gas decompression. Fretting tests revealed that the wear of these compounds is significantly affected by the hydrogen environment compared to air, especially with NBR grades. After the aging experiment, the friction response of the HNBR grades is characterized by increased adhesion due to elastic deformation, leading to partial slip. [ABSTRACT FROM AUTHOR]