Friction Performance Research Articles

Research on the influence of titanium addition on the structure and frictional performance of laser clad tin bronze coating

Cu has a high infrared light reflectivity, which leads to the easy formation of defects such as pores in copper alloys during the laser cladding process. The purpose of this research is to reduce the porosity of tin bronze coatings during laser cladding by adding titanium elements with high infrared absorption. The porosity of the coating was characterized using scanning electron microscopy, metallographic microscopy, energy-dispersive spectroscopy, and x-ray diffraction. The research results indicate that as the content of titanium element increases, the porosity within the coating first decreases and then increases. When the titanium addition was 2%, the minimum porosity of the coating was 0.034%. The microhardness of the samples was tested using a semiautomatic Vickers hardness tester, and the reciprocating dry friction performance at room temperature was tested using a UMT-3 friction tester. The incorporation of titanium significantly enhances the microhardness and frictional properties of the laser-clad tin bronze coating. Therefore, this study provides experimental data support for controlling the porosity and frictional properties of laser-clad tin bronze coatings through elemental composition.

Study on the friction and wear performance of graphene/porous bronze composites

Abstract The porous surface of air bearings may suffer from surface scratching and wear issues during the start-stop processes or under extreme working conditions. To enhance the lubrication properties and improve the service life of the porous restrictors, the graphene/porous bronze composites were prepared by combining powder metallurgy (PM) and chemical vapor deposition (CVD) in this study. On this basis, studies on the friction and wear performance of porous composites were carried out. The prepared porous composites and the friction surfaces were described by various means such as friction coefficient, morphology scanning, surface roughness, SEM, and EDS, which revealed the friction and wear process of the composites. Moreover, during the composite generation, the flow rates of carbon sources were set to be 3, 6, 9, and 12 sccm, respectively, to investigate the effect of graphene content on the lubrication properties of the original porous matrix. The experimental results showed that the lubricating performance of the composite was optimized at a flow rate of 12 sccm. Compared to the original porous bronze, the friction coefficient was decreased by 8.4%, and the wear rate was reduced by 10.5%. Furthermore, the research findings indicated that the grown graphene also affects the sintering process of the porous matrix, leading to weak connections between powders and differences in the final pore structure. Thus, the final pore structure, along with the presence of graphene, jointly influences the friction and wear performance of the porous composites.

Friction and Wear Performance of Composite SiC-YAG Thermal Spray Coatings in Water-Based Lubricants for Maritime Applications

AbstractThe tribological performance of four different thermal spray coatings has been tested against five different polymer seal materials in a fully formulated water-based lubricant. Water-based lubricants have been proposed for a marine application due to their environmental acceptability and their potential benefits when they are used in oil-to-sea interfaces minimizing the issues related to seawater contamination. The effect of normal load and speed on friction was studied for all seal-coating candidates. Hydrogenated acronitrile–butadiene rubber (HNBR) and ethylene–propylene–diene rubber (EPR) seals resulted in higher coefficient of friction (CoF) compared to ultra-high molecular weight polyethylene (UHMWPE), aliphatic polyketone (PK) and synthetic woven fabric impregnated with phenolic resin (SWF) plastic seals. This was attributed to the higher real contact area generated by the softer rubber seals compared to the harder plastic seals at the same normal load. From the point of view of the tribosurfaces tested in this work (hardened steel, WC-CoCr, Cr3C2-NiCr and SiC-YAG), friction and wear were controlled by two different mechanisms depending on the type of tribosurface. For metallic surfaces, the friction modifiers in the lubricant were adsorbed on the metals and controlled the frictional performance. The hardened steel (100% metallic surface) showed the lowest CoF, followed by the two cermet coatings (21-23 vol.% of metallic binder). The SiC-YAG coating (ThermaSiC) showed the best friction and wear performance due to the formation of a hydrated film on the SiC phase (77 vol.% of the surface) despite not having any metal matrix.

A first-principles calculations investigate the superlubricity and adhesion performance of structural superlubricity micro-components on polydimethylsiloxane surface

Adhesion and friction are crucial considerations in the design of microelectromechanical systems because they can directly influence the energy, dissipation and wear of the system. Current related studies are primarily conducted between graphite and hard materials, such as graphite, mica and gold, but lack the theoretical support of superlubricity on the surfaces of related flexible substrates, such as Polydimethylsiloxane (PDMS). Consequently, friction and wear at the flexible interface represent a significant challenge in the failure of microelectromechanical systems devices. In this paper, we use density functional theory to simulate the adhesion characteristics and friction behaviour of structural superlubricity micro-components on the surface of a flexible substrate in an atmospheric environment. The lower graphene layer of the structural superlubricity micro-components exhibits superior adhesion performance with the PDMS substrate. The increase in normal load is simulated by changing the spacing of layers. The interlayer bonding energy increases with increasing load. The transverse friction increases gradually with the increase in load, while the average friction coefficient decreases. Graphene can reach the superlubricity state on the PDMS substrate. The reliability of this phenomenon is verified by electrical performance. We also investigate the effect of tensile strain on the friction behaviour and electrical properties. These calculations should be combined with analysis of the mechanical properties to verify the reliability of the friction performance.

Numerical Study of Hydrothermal Enhancement of Two-Phase Flow in a Vertical Pipe by Using Modified Vortex Generators

The improvement in heat transfer and energy savings in two-phase (gas-liquid) flow in tubes occupies a wide area of research interest. In this work, the effect of modified twisted tape turbulators on heat transfer augmentation in vertical tubes is studied numerically by using the CFD technique. A vortex generator (twisted tape) was used as a passive method to raise the rate of heat transfer. The variants of the water flow rate, air flow rate, heat flux, and twisted ratio of a twisted tape tabulator were considered. This work provides a superficial water Re No. With ranges of 6300–10500, considering three different water and airflow rates. Additionally, the superficial gas Re range was 6000-16000. Three distinct twist ratios (TR) of 7.8, 3.9, and 2.6 were considered for the iron twisted tape to examine the impact of the twist ratio on the tube's thermo-hydraulic characteristics. The test section consisted of an insulated copper vertical tube subjected to three constant heat fluxes. This paper investigated three variants: the friction factor, Nusselt number, and performance evaluation factor. A strong turbulent vortex flow with an increase in secondary flow in the tube's radial direction was significantly intensified in the presence of the twisted tape inserted. Also, an increase in Reynold's number for both water and air and increased heat flux led to a proportional increase in heat transfer while the friction factor decreased. The presence of the modified twisted tape showed an improvement in the heat transfer and the pressure loss reduction when compared with the plain tape for all twisting ratios and for all cases where the highest value of the performance evaluation factor was two at the twisted ratio of 2.6 with an increase percentage of 81%. Conclusively, this investigation concludes that using modified twisted tape can greatly enhance the heat transfer rates and reduce pressure resistance, increasing the performance evaluation factor of heat exchanger systems.

Thermal oxidative aging behavior and lifetime prediction of fluoroether rubber

Fluoroether rubber's performance offers extensive application potential in harsh conditions. This article investigates the thermal-oxidative aging behavior and life prediction of fluoroether rubber using methods such as Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analyzer (TGA), Differential Scanning Calorimeter (DSC) and Compression Set. Results indicate that with prolonged aging, fluoroether rubber exhibits decreased heat resistance, damaged TAIC crosslink structures, and weakened characteristic peak intensities of main chains and side groups, leading to changes in rubber structure. Throughout the aging process, hardness, physical crosslink density, glass transition temperature, and compressive stress gradually increase, while mechanical properties decline. Using compression set as an indicator, service life at various temperatures was predicted, providing theoretical guidance for improving the reliability of fluoroether rubber seals and expanding their engineering applications.

Numerical Simulation and Experimental Investigation on Friction and Lubrication Behaviors of Chevron Micro-Textured Valve Plate/Cylinder Block Interface With Various Area Densities

Abstract As the critical friction pairs of swashplate-type axial piston pumps, the cylinder block/valve plate lubricating interface is the primary source of friction, wear, and leakage in axial piston pumps. Surface micro-texturing has been widely employed in cylinder block/valve plate conjunctions to ameliorate tribological performance. However, little research has been conducted to investigate the influence of chevron micro-texture area density on the tribological behaviors and lubricating properties of cylinder block/valve plate interface both experimentally and numerically. In this article, the chevron micro-textures with various area densities were manufactured on H62 brass by micro-milling and subsequently characterized with a laser scanning confocal microscope (LSCM). The friction and wear performance of H62 brass/38CrMoAl conjunctions were obtained via disc-on-disc tribological tests to simulate the cylinder block/valve plate lubricating interface. Moreover, the load-carrying capacity of untextured and chevron micro-textured samples was numerically investigated under hydrodynamic lubrication. It was found that the chevron micro-textured surface with an area density of 30.1% displayed the lowest friction coefficient and the shallowest wear depth. Although the load-carrying capacity of chevron micro-textured samples with a high dimple area density was larger, the severe stress concentration induced by the reduced micro-texture spacing caused the increment and large fluctuations of friction coefficient.

The Impact of Micro-texture Distribution on the Frictional Performance of Straight Bevel Cylindrical Gears

The Impact of Micro-texture Distribution on the Frictional Performance of Straight Bevel Cylindrical Gears

Exploring the wear mechanism of surface hardfacing Stellite 6 alloy on the cast iron over the wide temperature range

Abstract Cast iron is widely used as a heat-resistant material in the automotive industry, but it increasingly struggles to meet the demands of high-temperature friction applications. This study employs surface hardfacing with Stellite 6 alloy to improve the wear resistance of cast iron. By conducting sliding friction tests at various temperatures, we systematically investigate the friction behavior of both cast iron and hardfacing specimens over a broad temperature range. The results reveal that hardfacing-treated specimens exhibit exceptional wear resistance. At ambient temperatures, the hardfacing specimen shows a 65.5% reduction in wear loss compared to the cast iron specimen. This reduction increases to 83.8% at temperatures up to 600 °C. At room temperature, the wear mechanisms of cast iron include abrasive wear and fatigue wear. At medium temperatures, abrasive wear is the primary mechanism of cast iron. At high temperatures, the wear mechanisms of cast iron consist of abrasive wear, oxidative wear, and adhesive wear. In contrast, the wear mechanisms of the hardfacing specimens differ: at room and medium temperatures, abrasive wear is the predominant mechanism, while at high temperatures, the main mechanisms are abrasive wear and adhesive wear. The superior mechanical properties and enhanced resistance to high-temperature oxidation of the hardfacing specimens are the primary factors contributing to their improved friction performance across the temperature spectrum.

Effects of different interlayer bonding modes on the microstructure and properties of laser cladded In625

In this study, the effects of five different interlayer bonding modes on the microstructure, mechanical properties, friction, and wear resistance of In625 laser cladding were investigated. XRD, EDS, tensile, hardness, friction and wear tests were conducted. XRD analysis results have revealed that Nb6C5 was detected in rectangular ring mode and the long, wide and rectangular ring overlay mode, indicating that the rectangular ring mode may promote the formation of secondary phase. EDS analysis has indicated a slightly higher Nb content in the rectangular ring mode, while the long and wide direction overlay mode exhibited a more uniform grain distribution and smaller grain size. Tensile tests revealed ductile fractures in the long direction, wide direction, the long and wide direction overlay modes, while the rectangle ring mode and the long, wide, and rectangular ring overlay modes showed brittle fractures. The long and wide direction overlay mode had the highest average elongation (35.46 %), and the long, wide, and rectangular ring overlay mode had the highest tensile strength (957.13 MPa). Hardness test results showed that the rectangle ring mode had the highest hardness (325.1 HV (0.2)). Friction and wear tests indicated that the long and wide direction overlay mode exhibited the smallest wear volume (0.08899 mm3) and the best overall friction performance. These findings indicate that the properties of the cladding layer can be effectively tailored by selecting appropriate interlayer bonding modes to match the specific material requirements in distinct application scenarios.

Lubrication Characteristics of a Warhead-Type Irregular Symmetric Texture on the Stator Rubber Surfaces of Screw Pumps

A theoretical model for the micro-texture on the inner wall of the stator rubber in screw pumps was developed. The finite element analysis method was employed. The pressure and streamline distributions for warhead-type, concentric circle-type, and multilayer rectangular-type textured surfaces were calculated. The effects of textured morphology, groove depth, groove width, and other parameters on the lubrication field were systematically investigated and analyzed. A nanosecond laser was employed to process the textured rubber surface of the stator in the screw pump. Subsequently, a micro-texture friction performance test was conducted on the rubber surface of the stator in actual complex well fluids from shale oil wells. Given the results of the simulation analysis and experimental tests, the lubrication characteristics of textured rubber surfaces with varying texture morphologies, rotational speeds, and mating loads were revealed. Furthermore, it indicated that the irregular symmetric warhead-type micro-texture exhibited excellent dynamic pressure lubrication performance compared with concentric circle-type and multilayer rectangular-type textures. The irregular symmetry enhanced the dynamic pressure lubrication effect, enhanced the additional net load-bearing capacity of the oil film surface, and reduced friction. As the groove depth increased, the volume and number of vortices within the groove also increased. The fluid kinetic energy was transformed into vortex energy, leading to a reduction in wall stress on the surface of the oil film, thereby affecting its bearing capacity. Initially, the maximum pressure on the wall surface of the oil film increased and then decreased. The optimal dynamic pressure lubrication effect was achieved with a warhead-type texture size of 3 mm, a groove width of 0.2 mm, and a groove depth of 0.1 mm. Well-designed texture morphology and depth parameters significantly enhanced the oil film-bearing capacity of the stator rubber surface, improving the dynamic pressure lubrication effect, and consequently extending the service life of the stator–rotor interface in the screw pump.

Investigating Influence of Mo Elements on Friction and Wear Performance of Nickel Alloy Matrix Composites in Air from 25 to 800 °C

Rapid developments in aerospace and nuclear industries pushed forward the search for high-performance self-lubricating materials with low friction and wear characteristics under severe environment. In this paper, we investigated the influence of the Mo element on the tribological performance of nickel alloy matrix composites from room temperature to 800 °C under atmospheric conditions. The results demonstrated that composites exhibited excellent lubricating (with low friction coefficients of 0.19–0.37) and wear resistance properties (with low wear rates of 2.5–28.1 × 10−5 mm3/Nm), especially at a content of elemental Mo of 8 wt. % and 12 wt. %. The presence of soft metal Ag on the sliding surface as solid lubricant resulted in low friction and wear rate in a temperature range from 25 to 400 °C, while at elevated temperatures (600 and 800 °C), the effective lubricant contributed to the formation of a glazed layer rich in NiCr2O4, BaF2/CaF2, and Ag2MoO4. SEM, EDS, and the Raman spectrum indicated that abrasive and fatigue wear were the main wear mechanisms for the studied composites during sliding against the Si3N4 ceramic ball. The obtained results provide an insightful suggestion for future designing and fabricating solid lubricant composites with low friction and wear properties.

Enhancement of friction and wear performance of polytetrafluoroethylene composites through the synergistic effect of hard fillers

AbstractThe Stirling engine is a high‐efficiency externally heating piston engine. The self‐lubricating properties of polytetrafluoroethylene (PTFE) are crucial for the operation of Stirling engines. Three PTFE composites filled with different contents of carbon fiber (CF), polyimide (PI) and nano‐zirconia (nano‐ZrO2) were prepared and their mechanical, friction and wear properties were investigated. The results showed that the density of CF‐containing PTFE composites was significantly reduced by 1.46% to 6.9% compared to neat PTFE. Meanwhile, the incorporation of fillers greatly enhanced the hardness by more than 21.4% over the hardness of neat PTFE. In addition, the friction coefficients of three PTFE composites were lower than those of neat PTFE, and the wear rate of these composites was three orders of magnitude lower than that of neat PTFE. In particular, the wear rate of PTFE filled with CF and PI at high pressure (2 MPa) and high velocity (4 m/s) was only 1.24 × 10–6 mm3/Nm. The wear morphology was also analyzed by scanning electron microscopy and energy‐dispersive x‐ray spectroscopy. It was found that the addition of CF and PI in PTFE has the most pronounced improvement on tribological performances. The synergistic effect of CF's mechanical reinforcement and PI's adhesive properties reduces the wear of the matrix, resulting in excellent wear resistance of PTFE composites.Highlights The compressive strength of PTFE was reinforced by CF and nano‐ZrO2. CF can lower the density and significantly enhance hardness of PTFE. Synergistic CF and PI enhance PTFE composites' friction & wear performance. Adhesive fillers & debris size key to forming uniform continuous transfer films.

Fabrication and tribological behaviors of copper fiber and carbon fiber reinforced phenol‐formaldehyde resin‐based composite for sliding current collector

AbstractTo achieve new current collector (pantograph strip, electric brush) with easy industrialization and high strength‐toughness, carbon fiber and copper fiber reinforced phenol‐formaldehyde (Cuf/Cf/PF) composite is fabricated by over‐lapping and hot‐pressing processes. Cuf/Cf/PF composite has compact structure and good interfacial bonding between fibers and resin matrix. Cuf/Cf/PF composite is superior to carbon skateboard in terms of electrical conductivity, mechanical strength, and friction behavior. As the carbon fiber content increases, fracture failure mechanism of Cuf/Cf/PF composite transforms from plastic failure into brittle fracture. Wear mechanism is studied by combining electrical contacting and sliding friction, and appropriate arc discharge (2.48%) is benefit for the resin‐based composite to form a smooth tribolayer, but high arc discharge rate (4.83%) rapidly deteriorates wear condition on the worn surface.Highlights Carbon fiber and copper fiber mixing reinforce resin‐based composite. Cuf/Cf/PF composite has high strength‐toughness and low friction. Fracture failure mode changes to brittle fracture with increasing carbon fiber. Wear mechanism includes electrical contacting and sliding friction. Appropriate arc discharge improve friction performance of resin‐based composite.

Study on influence of friction conditions on the friction and wear performance of high-speed rail brake materials under high humidity environment

Purpose Using the multifunctional friction and wear testing machine independently developed by the research group, the friction and wear tests of different friction conditions (contact pressure and sliding speed) are conducted on the brake materials of high-speed trains with the ambient humidity of 95% and the initial temperature of the disk of 200°C. Design/methodology/approach Friction and wear. Findings The test results show that changing the friction conditions has a significant effect on the braking performance of high-speed trains. Originality/value YES. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0171/

Simulation analysis and experimental research of friction performance between wood and cemented carbide surface with different micro-textures

ABSTRACT Reasonable micro-pit texture has been proved to be able to improve the friction characteristics between wood and cemented carbide. In this paper, the finite element simulation analysis was used to simulate the friction surface stress, the simulation model was determined, and the simulation results were combined with the friction characteristics test to study the influence of different texture types on the friction coefficient of the wood surface. The results show that the friction coefficient and the stress magnitude of friction between cemented carbide and wood surface have a good linear correlation (R 2 = 0.9414), the finite element simulation can provide a reference for the study of friction behavior in the wood cutting process. The friction coefficient can be influenced by texture parameters such as texture type, the friction length, the width of micro-texture and the angle of micro-texture. Under the condition of the same texture area occupancy, the surface friction coefficient of the micro-pit texture is the smallest; the surface friction coefficient of the micro-groove texture is the largest, and the micro-grid texture has the smaller friction coefficient with the decrease of the texture angle. This is related to the actual contact area between the texture area of the friction area and the wood surface and the main braking force generated during contact.

Wear Friction and Corrosion Performance Assessment on IF, HSLA and DP600 Steels Subjected to Severe Vibratory Peening

Wear Friction and Corrosion Performance Assessment on IF, HSLA and DP600 Steels Subjected to Severe Vibratory Peening

Python-based machine learning estimation of thermo-hydraulic performance along varying nanoparticle shape, nanofluid and tube configuration

In this research article, a Python-based machine learning model prediction study was conducted based on the study results obtained from sudden expansion tubes containing different expansion angles, dimpled fin structures and nanofluids, whose thermo-hydraulic performance was previously examined. In the study, Artificial Neural Network and Ridge regression models were used to make predictions on the average Nusselt number (Nu), average Darcy friction factor (f) and performance evaluation criteria (PEC). Physical variations of the sudden expansion tube were taken into account and a detailed comparison of the results was made. A superior average Nu was acquired as 172.45 %, 22.05 %, 17.18 %, 13.65 %, and 7.76 % compared to Ag-MgO/H2O, Al2O3/H2O (blade), CoFe2O4/H2O, Al2O3/H2O (cylindrical), and Al2O3/H2O (platelet), respectively. The highest Performance Evaluation Criteria (PEC) for Re= 2000 based on Al2O3/H2O (platelet) shows an increase of 4.84 %, 12.08 %, 11.76 %, 66.05 %, and 148.94 % compared to Al2O3/H2O (cylindrical), Al2O3/H2O (blade), CoFe2O4/H2O, Fe3O4/H2O, and Ag-MgO/H2O, respectively. From the results obtained, it was determined that Python-based Machine Learning approach which facilitates custom optimizations showed a significant performance with small margins of error in predicting the heat transfer parameters. The lowest error rates of machine learning and polynomial ridge regression models ranged from 0.2 % to 5.4 % for the unseen test set and the application of Python-based algorithms provided considerable savings in calculation time compared to conventional methods. On the other hand, using machine learning models with feature engineering has been found to increase model performance by at least 30 %. In these years when studies on the predictions of thermo-hydraulic studies are very rare in the literature, this study is intended to facilitate scientists, engineers and academicians who will further study on this subject.

The Role of Functionalized CuO Additive in Enhancing Tribological Performance of Plastic Oil Lubricant

ABSTRACTThe study investigated the potential of waste plastic oil (PO) as an alternative to petroleum‐based lubricants, specifically mineral oil. The rheological properties, dispersion stability, friction, and wear performance of PO were examined and compared with mineral oil. Results showed that PO demonstrated similar lubrication performance to mineral oil. To enhance the lubrication performance of PO, the study incorporated various concentrations of nano CuO solid lubricant additives, resulting in the formation of CuO nano lubricants. These lubricants showed an improvement in friction and wear by 20% and 44% compared with PO. Furthermore, the CuO solid lubricant additives were functionalized and incorporated in the same concentrations into PO, resulting in the formation of functionalized nano lubricants, which further lowered the friction and wear by 28% and 91% compared with PO. The novelty of the paper is that a simple chemical functionalization process that not only helped in improving its dispersion stability of additives in the PO, but also enhanced the wear performance. The mechanisms behind the enhancement of friction and wear performance were discussed. Based on these findings, it can be concluded that incorporating functionalized nano additives in PO improve friction and wear performance in mechanical components, promoting wider utilisation of PO.

Effects of Intercalation on ML-Ti3C2Tz MXene Properties and Friction Performance.

Intercalation in two-dimensional (2D) materials can modify their physical, chemical, and electronic properties. This modification enables the tailoring of 2D material characteristics, enhancing their performance and expanding their applications in various fields. The friction performance of 2D materials such as MoS2 and graphite has a strong dependence on their interlayer spacing, and they exhibit an increase in d-spacing associated with a reduction in friction performance. The ability to control the interlayer spacing of Ti3C2Tz MXene has proven beneficial for energy storage applications such as batteries and supercapacitors, but no one has utilized this control of interlayer spacing for lubrication. In this study, we demonstrate that interlayer spacing of multilayer (ML) Ti3C2Tz MXene can be controlled through chemical intercalation and its direct effects on the electrical conductivity and friction performance. We observed a notable decrease in electrical conductivity in vacuum-filtered ML-Ti3C2Tz MXene films, which was attributed to an increased internal resistance resulting from the expansion of the interlayer gap. We also found a significant reduction in the coefficient of friction for ML-Ti3C2Tz MXene with an increased d-spacing. This reduction is attributed to a weakened attraction of individual ML-Ti3C2Tz MXene layers (intercalated). Under a tangential force, it becomes easier to slide within the larger interlayer gap with weakened van der Waals forces. This work provides insights into the tunability of MXene properties through interlayer spacing, offering potential applications requiring materials with specific electrical and friction characteristics.