A recent interest on emergency shoe braking in high speed trains stimulated the research on the damage due to sliding contact between brake blocks and wheel tread. Bi-disc tests, with rolling/sliding contact between specimens extracted from wheels and brake blocks, were previously performed in constant working conditions to reproduce the temperature of the wheel during stop braking. However, stop braking

The commonly used quasi-static model for angular contact bearings is enhanced by coupling the contact mechanics and bearing kinematic analyses with traction or friction behavior in ball-to-race contacts. The points of pure rolling in the contacts, which constitute the primary inputs in the kinematic equations, are determined by minimizing the frictional dissipations based on a prescribed elastohydrodynamic

One of the urgent problems that have yet to be addressed in the field of drilling engineering is how to further improve the working performance of rock bit journal bearings (RBJBs) and prolong its service life under complicated conditions of low speed, heavy load, and high temperature. Generally, reasonable surface texture parameters serve as an effective means for enhancing the lubrication and anti-wear

An innovative VCN coating with C element doped in VN matrix was developed on Inconel 718 and Si (100) substrates using a multi-arc ion plating technique. The micro morphology and microstructure of the as-deposited VCN coating were studied by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscope (XPS). The results show that the incorporation

Magnetron sputtered PVD thin-film TiB2 coatings were investigated to be a wear-resistant cam tappet coating which runs under the boundary lubrication regime in internal combustion engines (ICEs). A high negative biased AISI 52100 samples were coated at RF powers of 150, 170 and 190 W. Coatings were characterized via nanoindentation, SEM/EDX, XRD and Raman analysis. Friction and wear behaviors of these

Electroplated bolts have been widely used in the automotive industry for many decades. In the present work, for the first time, the role of each layer of the bolt coating (i.e., electroplating, passivate and topcoat layer) on the coefficient of friction of a bolted joint were experimentally and systematically investigated. The coefficient of total friction (μtot), coefficient of friction between threads

Copper and graphite are main compositions of copper-based brake materials commonly used in the field of high-speed train. Their interaction influenced the tribological performance of copper-based brake materials. In this paper, with copper and graphite as compositions, three kinds of layered samples were prepared as pins, which were tested against the disc made of H13 steel. Friction tests were conducted

Due to the unique redox characteristic of CeO2, addition of CeO2 in diesel fuel reduces diesel engine emissions; however, its influence on the friction and wear performance of the fuel injection system is not clear. In this work, CeO2 were synthesized and modified. CeO2-diesel fuel blends with different concentrates prepared. The dispersion stability of the CeO2 and modified CeO2 in diesel fuel blends

ABSTRACT A simple and inexpensive corrosion sensor has been manufactured to study the corrosion rate of new and water contaminated lubricating grease using a galvanic cell. The galvanic charge is developed between ENIG (electroless nickel immersion gold) and zinc, manufactured by selectively plating on a custom manufactured interdigitated PCB (printed circuit board). This paper shows the methodology

An abnormal phenomenal of rail corrugation was found in the transition and circular curve interval of the mountain city metro, in which the rail corrugation on the outer rail is more serious and earlier than that on the inner rail, and the wavelengths are also different. In the present paper, the frictional self-excited oscillation of the wheel-rail system and the feedback vibration of the rail corrugation

To reduce the irregular typewriter noise in main bearings of engine, a comprehensive experimental study about the effect of carbon black particles (CBPs) with different particle sizes, concentrations and standing times on noise in the oscillatory parallel plate squeeze oil film test apparatus has been carried out. The results show that the presence of CBPs can significantly reduce the generation of

This paper presents a numerical analysis of elastohydrodynamic lubrication (EHL) with grease in point contacts to predict the grease film thickness at low speeds, which can increase with decreasing the speed and exceed the base oil film thickness by orders of magnitude. The grease film thickness is obtained by solving the EHL problem, taking grease flow as a single-phase flow with a non-Newtonian viscosity

There is a grinding fine grain layer of high-speed train wheel after machining treatment. In this paper, the influence of grinding fine grain layer on rolling contact fatigue (RCF) property is studied by GPM-30 fatigue tester. The results show that there is a 1μm thickness fine grain layer after grinding treatment. The grinding fine grain layer can improve the RCF life of wheel samples. The formation

The relatively high toughness, high adhesion to steel, and low internal stress of hydrogenated amorphous carbon (a-C:H) films containing Ag make them good candidate materials for various applications in sensors, tribology, and biomaterials; however, the relatively low hardness and poor tribological properties in oxidizing environments hinder their broad use. Incorporating a small amount of Si in Ag/a-C:H

In gear transmission systems, the reliability of lubrication is essential to its life. An approach to predict the reliability of gear elastohydrodynamic lubrication (EHL) under a random input torque is proposed in this paper. Firstly, a single-freedom nonlinear stochastic dynamic model that considers backlash, a time-varying mesh stiffness, and random loads is established to obtain the probability

The present work aims to investigate the sliding friction and wear behavior and related emissions of airborne particulate matter of Cu-free barite containing friction materials for vehicular brake pads. In particular, the effect of different concentrations of phenolic resin used as a binder has been considered. Tribological tests were conducted using a pin-on-disc laboratory tester. During running-in

The braking performance of copper-based brake pads containing Cu-coated SiO2 and uncoated SiO2 was tested on a reduced-scale dynamometer. Results showed that both the stability of the friction coefficient and the wear resistance are improved and the fade phenomenon of the friction coefficient is effectively alleviated during continuous emergency braking (350 km/h, 0.48 MPa) by introducing Cu-coated

Wet clutches are widely used in vehicle transmission systems to start and shift. The temperature field of the wet clutch components is influenced by friction and is closely related to the vehicle performance and service life. This work improves the numerical modelling of the temperature field by taking into account the groove cooling, the local heat dissipation and the time-varying friction coefficient

Water-miscible metalworking fluids (MWFs) are used in metal removal and forming operations. For end-use, formulation concentrates are diluted in water - providing conditions conducive to microbial growth and metabolism, and potentially causing fluid biodeterioration and microbiologically influenced corrosion. Microorganisms in the environment are highly diverse and bacteria and fungi had been recovered

The tribological performance of ceramic–polymer composites prepared by high-pressure (3 GPa) compression molding of silicon nitride (Si3N4) and polytetrafluoroethylene (PTFE) with epoxy resin (EP) binder was investigated under dry friction conditions. Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy, and energy-dispersive spectroscopy (EDS) were utilized to

The tribological behaviors of silicon nitride sliding upon sintered polycrystalline diamond (PCD) were explored via altering pH levels. High reductions in the friction and wear are achieved when sodium hydroxide solution is introduced at the contact interfaces. This reduction is found to depend on the pH value of the alkaline solution. The friction coefficient and wear loss of silicon nitride vary

This work presents an approach for modeling grease-lubricated bearing wear by coupling models for boundary-lubricated wear and bearing lubrication state. The lubrication model takes a mass balance approach, using previously developed models for pressure-driven side flow loss and centrifugally driven bleed supply mechanisms. These are combined with a contact model to determine the level of surface interaction

For over a decade, hard coatings have been providing wear resistance to cutting tools materials. The industrial prerequisites and advancements in hard coatings provide drastic improvements with respect to productivity and component lifetimes and hence reduce cost. However, selection of a desirable coating is often not straight forward, in view of the fact that the number of hard coating materials and

In complex operational environments, random shocks change the contact behavior of rough surfaces, resulting in time-dependent and uncertain characteristics, which further affect their friction, wear, and lubrication properties. However, in the currently available impact models, only deterministic shocks are considered at surfaces in contact and the evolution of contact behavior over time is ignored

Chain continuously variable transmissions (CVTs) are attracting attention as the next-generation practical application, which utilize lubricated rolling/sliding contacts for transmitting the engine power. However, their flexible structure sometimes causes vibration and noise problems which need to be solved. In this study, friction tests were conducted for a rolling/sliding contact lubricated by test

Hybrid pump-controlled asymmetric cylinder drive systems are implemented for energy-saving purposes in applications that do not require fast responses. Under low-velocity and low-pressure conditions, the friction influence in the hybrid pump-controlled system is evident. Researchers have developed various models to describe friction. These friction models are implemented based on the relative motion

High-performance coatings with self-lubrication, superior wear and corrosion resistance are sought-after in modern industry. Here we reported a Cobalt-Nickel/Tungsten disulfide (Co-Ni/WS2) composite coating fabricated by a pulse electrodeposition approach. The codeposition of WS2 significantly affects the microstructure, hardness, tribological and electrochemical behaviors of the Co-Ni/WS2 composite

This article aims to investigate tribological properties of a surface modified by laser texturing under full oil lubrication as well as the effect of laser texturing on the abrasion resistance properties. Laser texturing was carried out to fabricate a spherical bulge texture on the surface of GCr15 bearing steel using an SPI fiber laser. Rriction and wear tests were performed to simulate the actual

The premature failure of cutting tools during machining of titanium alloys is primarily attributed to their low thermal conductivity and strain hardening. The coefficient of friction (CoF) at the tool-chip contact depends on the high stress-strain values, interface temperatures, and the velocity of the chip. In this work, a new tribometer is developed to overcome the drawbacks of the existing tribometer

The effects of ultra-high-molecular-weight polyethylene (UHMWPE) as a filler on the tribological and mechanical properties of two biocompatible epoxies were studied. SU-8 and Structalit 8801 (a trade name) were the two biocompatible epoxies selected for this investigation. UHMWPE powder (40–48 μm particle size) was added to the selected epoxies to tailor their mechanical and tribological properties

Numerical models for barrel-shaped rings with four textures were established using MATLAB and the corresponding specimens were fabricated by laser surface texturing. The performance was compared both theoretically and experimentally in order to investigate the effects of geometrical characteristics. The results of the theoretical analysis indicated that a microdimple texture on both sides of the ring

This work presents a tribological evaluation of the influence of graphite and bronze fillers in two commercial composites in a dry sliding pin-on-disc test at the same contact severity ( PVa parameter) and four testing conditions (varying both normal force and sliding velocity). Both fillers, in comparison to pure PTFE, significantly affected the coefficient of friction (COF) and the mass loss. The

(Ti,Mo)B2-(Ti,Mo)C-(Fe,Cr)7C3 particle-reinforced laser cladding coatings with different contents of Y2O3 were prepared on a hot forging die steel substrate. The microstructure and wear behaviors were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), block-on-ring room temperature wear testing, and ball-on-disc high-temperature wear testing. The results showed that rectangular-like

This study is a continuation of our previous work. It aims to characterize the tribomechanical and tribochemical behaviors of Ti3SiC2 in low-viscosity liquids. We found an interesting phenomenon in which the flowing and nonflowing states of ethanol are related to the tribological behavior of Ti3SiC2. Low friction and wear were obtained in flowing ethanol, which is due to the lubrication of the products

High-chromium cast iron with high nitrogen content (HNHCCI) was prepared using a vacuum induction barotropic furnace, and the erosion–wear behaviors of HNHCCI were investigated with a rotary erosion–wear tester. Results show that most of the nitrogen in HNHCCI dissolves into the matrix and some nitrogen forms carbonitride in the solidification process. The relative wear resistance of HNHCCI can reach

Arbitrary velocity vectors on two meshing surfaces in spiral bevel gears could generate large sliding velocity, which may cause a tremendous temperature rise, especially when surface roughness is involved. However, available studies are primarily concentrated on full-film lubrication without considering temperature rise and surface topography. The purpose of present study is to develop a mixed thermal

The performance of surface-active additives, such as friction modifiers, depends on their interactions with surfaces. Their effectiveness thus hinges upon the surface conditions. In this work, the effect of cleaning methods of test substrates on the friction reduction capabilities of different organic friction modifier (OFM) additives was investigated. 52100 steel discs and balls were the test specimens

In order to study the tribological properties of PTFE modified by hard nanoparticles and soft polymer under dry friction conditions, the tribological properties of polytetrafluoroethylene (PTFE) filled with different volume contents of polyether ether ketone (PEEK) and nano-ZrO2 were investigated at a linear speed of 2 m/s, normal load of 200 N, and ambient temperature conditions for 60 min using a

Abstract Earlier studies have shown that the load-dependent friction behavior of various gear oils can affect their pitting performance; that is, low friction resulted in a long pitting life. These studies were limited, however, to test methods and running conditions quite different from those occurring in actual gear transmissions. In the present study, a more gear-like twin-disc machine with test

Carburizable martensitic stainless steels (MSSs) are attractive candidates for bearings due to their high corrosion resistance, high hardness, and high temperature performance. Wear performance in tribocorrosion applications is strongly influenced by the surrounding environment. Electrochemical testing was used to evaluate three different surface treatments on AMS 5930 steel developed for advanced

A 3D finite element (FE) model was developed to investigate the effects of refurbishing on rolling contact fatigue (RCF) behavior of through-hardened bearing steel in a circular contact. In this investigation, the material degradation due to fatigue in original and refurbished domains was modeled using continuum damage mechanics (CDM). Material damage, crack initiation, and propagation in a circular

This study investigates the performance of three ionic liquids (ILs), trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate, trihexyl(tetradecyl)phosphonium decanoate, and 1-butyl-3-methylimidazolium tetrafluoroborate, as lubricant additives in synthetic oil polyalphaolefin (PAO8) and bio-based oil trimethylolpropane trioleate (TMPTO). The ILs were added at 0.5, 1.0, and 1.5 wt% concentrations

An experimental study is conducted for friction systems introducing damping components consisting of different materials and different configuration. A number of experiments are performed on a pad-on-disc experimental test rig. Dynamic and tribological analyses are performed to evaluate the effects of different damping components on the stick–slip behavior. The obtained results indicate that friction

In some industrial devices, the use of a sliding contact to transmit power currents or communications signals is required. The physical and, in particular, tribological understanding of these electromechanical systems is therefore a major issue. Thus, this article reports a theoretical and numerical study accounting for the mechanical influences about the electric transport properties of a sliding

Both the mechanical properties and friction characterization of graphene–silicone rubber composites were investigated systemically. Graphene–silicone rubber composites were prepared by means of solution and flocculation process to improve the processing performance and avoid agglomeration. It was found that the tensile strength, elongation at break, and tear strength of graphene–silicone rubber composites

FeS-Cu copper-based self-lubricating bearing materials are prepared by mechanical alloying and powder metallurgy. The effects of ball milling time on the microstructure and properties of the material are analyzed. The dry friction properties of the material are tested on a pin–disc contact reciprocating test machine with the load of 200·N. The morphology and composition of the wear surface are observed

Tests were conducted to identify and understand the failure mechanisms that control a gear’s longevity during a loss of lubrication (LoL) event by tracking the physical and tribological changes experienced by the gear teeth from operating without oil. A total of five tests were performed using 28-tooth, eight-pitch spur gears made from AMS 6308 on a single-mesh test rig. A new set of gears was used

In this study, a rough-surface thermal elastohydrodynamic lubrication (TEHL) model, which is tailored for the simulation of high-speed and high-temperature contacts of relatively smooth surfaces, is introduced. The model uses the Modified-Carreau-Yasuda constitutive function to capture the non-Newtonian effects, and a limiting shear formulation to consider any lubricant-solid slippage. It is employed

A novel flexure pivot tilting pad squeeze film air bearing (FPTP-SFAB) based on near-field acoustic levitation (NFAL) for a rotor is proposed in this article. The most important advantage of this structure is the suitability of the bearing for high-speed and light load conditions because the FPTP can adapt well to squeeze action during operation. The rotating orbit of the rotor can be adjusted according

B4C ceramics were fabricated by pressureless sintering, and the tribological behaviors of B4C ceramics without and with a postannealing treatment at different temperatures were investigated. It was found that the pores of B4C ceramics prepared by pressureless sintering might cause large fluctuations in the coefficient of friction but did not increase the coefficient of friction. A B2O3 layer was not

Helicopter drivetrain components depend on oil lubrication to maintain elastohydrodynamic lubrication between sliding surfaces and are susceptible to a loss of lubrication event. A loss of lubrication event starves the mechanical interfaces of oil, pushing them from elastohydrodynamic toward mixed and boundary lubrication regimes. In those regimes, scuffing initiation and thermal runaway occur, resulting

Calculation with the determined load is more useful for engineering applications because the external load is easier to obtain than the bearing eccentricity. However, the calculation method based on the determined load for a journal bearing with a complex structure is still difficult to meet requirement. This article presents a calculation method to seek proper bearing eccentricity with a determined

Fretting wear has a significant influence on wire rope fatigue life when in cyclic bending, particularly for crossed wire contacts, where the interfacial motion of the surfaces is complex and multi-axial. To simulate these contacts in a controlled manner, a laboratory-scale, crossed cylinder, reciprocating fretting wear test was developed. A broad range of contemporary lubrication technologies were

This work improves the tribological behavior via innovative surface designs for slipper pairs in seawater axial piston pumps. 316L stainless steel and carbon fiber/polyether ether ketone (CF/PEEK) were selected as friction pair matching materials due to their good corrosion resistance, self-lubrication, and wear resistance. One type of smooth surface and five different types of pit nonsmooth surfaces

A finger seal is a flexible and dynamic contact seal, and many researches and experiments have proved its application potential in aviation engines, gas turbines, and other equipment. However, the contradiction between hysteresis leakage and wear life in the design and initial installation condition of finger seals seriously affects the integrated performance design effect. A variable stiffness finger

No single lubricant can provide effective lubrication in various environments. In this study, both graphene (RGO) and WS2 were added to the Cu matrix to prepare self-lubricating composites that can adapt to different environments. Three kinds of Cu-based composites containing different volume ratios of lubricants were fabricated by a hot-pressing method. The physical and mechanical properties of the

Novel interpenetrating phase composites (IPCs) were produced by infiltrating ZA8 alloy into sintered 304 stainless steel fiber preforms through squeeze casting. Microstructural characteristics and dry sliding wear behavior of the IPCs at room and elevated temperatures under different applied loads were investigated. The results indicate that the microstructures and wear behavior of the IPCs exhibit

In this study, the effects of polytetrafluoroethylene (PTFE) thickness on the wear and friction properties of spin-coated PTFE and polydopamine (PDA)/PTFE coatings on stainless steel (SS) substrates were investigated. The PTFE coating thickness was varied by controlling the number of PTFE spin-coating deposition cycles. The PDA/PTFE coatings showed 1.4 to 4.9 times the wear life of that of the PTFE

In order to study the frictional behavior of a roller linear motion guide (RLMG) in mixed elastohydrodynamic lubrication (EHL), a micro–macro contact analysis is employed to analyze the contact parameters at the contact surface, such as the contact load and deformation, shear stress due to sliding effect, and shear stress of the lubricant. Then a friction model is developed via the combination of local

As-cast white cast iron specimens with chromium concentrations of 0, 2, and 4 wt% were prepared by melting and casting. Scanning electron microscopy and X-ray diffractometry results indicate that the composite phase consists of a hard phase (cementite) and a toughness matrix (pearlite) with a 28.8 ± 2% cementite volume fraction, which is a typical hypoeutectic structure. The cementite and pearlite