Surface Friction Research Articles

Preparation of In-Situ Reaction Particle-Reinforced Titanium Matrix Composites Layers by Friction Surfacing

Preparation of In-Situ Reaction Particle-Reinforced Titanium Matrix Composites Layers by Friction Surfacing

Influence of mode and design factors on the temperature condition of automobile drum brakes

The current state of the highway pavement makes it possible to implement prompt transportation operations. These circumstances lead to the movement of vehicles at high speeds, which is impossible without a braking system capable of ensuring high braking efficiency and optimal flow of the process from the standpoint of stability and controllability. One of the main requirements for a modern automatic transmission braking system is the stability of the initial parameters, that is, parametric reliability. Therefore, it is important to have data on the brakes' operating modes and energy consumption. Only with such data is it possible to create a braking system whose output characteristic will be sufficiently stable under conditions of high energy load. Therefore, it is no coincidence that the international methodology for testing the effectiveness of vehicle brakes (UNECE Rule 13) provides for Test I, which is characterized by cyclic braking (urban conditions), and Test II, which is characterized by prolonged braking (mountain conditions). The brake mechanism is the most unstable link of the brake system; one way to increase its efficiency is to ensure sufficient energy capacity, which is limited by the temperature of the friction surface. The object of the study is the question of the equivalence of the change in the drum radius and the width of the friction belt of the brake, taking the invariance of the temperature of the friction surface under the selected test mode as the criterion of equivalence. It is shown that the role of the drum's side wall on the brake's temperature mode under different test modes can also be evaluated on grid thermal models with the involvement of the "Fourier–2 x,y,z" software complex. The effect of the heat transfer coefficient on the temperature mode of the brake due to the consideration of the gap between the drum wall and the wheel rim is shown. Derived formulas for determining the friction belt's equivalent width under the equality of heat flows, masses, and cooling surfaces.

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.

Influence of fly ash and waste tire rubber particles on mechanical and tribological properties of composite brake linings

AbstractTo investigate the influence of waste tire rubber (WTR) and fly ash (FA) on mechanical and tribological properties of composite brake linings, 8 different formulations of 8–40 wt% FA and 10–12 wt% WTR were selected. The mechanical tests showed that high amounts of resin and FA result in the highest hardness. The inclusion of WTR, decreased hardness and internal shear strength; however, increased the acetone extraction and resistance to coefficient of friction (COF) fluctuations. With the use of WTR, steady COF fluctuations with the temperature changes are achieved. The tribological properties were evaluated with both a drum‐type and disc‐type dynamometer by the SAE‐J661 standard. Reduced COF fluctuations were observed in <15 wt% FA and 10 wt% WTR containing samples. The highest COF was obtained for the 14 wt% FA and the lowest wear rate for the samples containing 8 wt% FA. The brake composites exhibited consistent COF in the range of 0.34–0.52, and wear rates lower than 7 wt%. Two compositions containing 40 and 25 wt% FA (no WTR), and one containing 10 wt% WTR and 8 wt% FA provided the best results. Finally, four best compositions were selected and worn surfaces were analyzed with SEM after full‐scale dynamometer tests.Highlights Three composites with high waste percentage were successfully manufactured Fly ash and waste rubber are used without any post‐processing to cut costs Waste rubber increased resistance to COF fluctuations with temperature change Full‐scale dynamometer tests are performed for friction and wear properties Worn surfaces were analyzed with SEM method

Research on Oscillation Suppression Control Method for Contact Scanning Motion

Contact scanning sensors play a crucial role in certain detection equipment, enabling the precise identification and detection of structural degradation to effectively mitigate risks. However, these sensors face a challenge: during high-speed scanning, vibrations can occur due to surface unevenness and friction. These vibrations not only compromise the scanning accuracy but also expedite sensor wear and tear. To address this issue, this study introduces a control strategy. By precisely regulating the actuator’s output, we aim to adjust the sensor’s motion, minimizing vibrations and enhancing the detection system’s stability and accuracy. Simulation results demonstrate that this strategy significantly improves scanning quality and reduces vibrations, validating its effectiveness. These findings pave the way for future research and technological applications.

A comparative analysis of different surface tribological and electrochemical properties of TiAlN, TiAlSiN, and CrAlN thin film coatings in seawater

Abstract To reveal the wear mechanisms of TiAlN, TiAlSiN, and CrAlN coatings in a seawater environment, the changes in frictional surfaces and the electrochemical characteristics of these coatings were compared and analyzed in this paper. The coatings were deposited on 316L stainless steel surfaces. Tribological tests were investigated using a ball-on-disk tribometer with Si3N4 ceramic balls as the counter material. Although the friction coefficient of 316L stainless steel was the lowest at 0.34, the order of wear rates was 316L stainless steel (7.38×10-5)>TiAlN(5.31×10-6)>TiAlSiN(4.23×10-6)>CrAlN(1.10×10-6) and the electrochemical protective efficiencies of TiAlSiN and CrAlN were both greater than 97%. Seawater penetrated through the grain boundaries of the TiAlN coating, which led to corrosion and delamination failure. Conversely, the grain refinement in TiAlSiN and CrAlN coatings can significantly slow down the penetration of seawater into the coating under frictional pressure, and the oxide lubricating layer formed during the friction process can become an effective barrier to isolate seawater. Therefore, mechanical wear was the main wear form of these two coatings. Additionally, among the oxides formed in the friction, Cr2O3 showed the strongest corrosion resistance, making the CrAlN coating exhibit superior wear resistance and the lowest wear rate in seawater.

Lubrication performance of 5CB liquid crystal combined with different wear-resistant coatings on friction surface

Lubrication performance of 5CB liquid crystal combined with different wear-resistant coatings on friction surface

Removal of Surface Radioactive Uranium(Ⅵ) by Graphene Oxide Modified κ-carrageenan/Konjac Glucomannan Composite Hydrogel

Hydrogel is an effective surface decontamination technology. However, traditional colloid decontaminants face a long curing time and low decontamination rate. A peelable hydrogel coating composed of carrageenan, konjac glucan, and graphene oxide with excellent film-forming performance and decontamination efficiency was explored in this study. The results showed that the graphene oxide was effectively dispersed inside the hydrogel, improving the crosslink density and thermal stability of the hydrogel by forming hydrogen bonds with polysaccharide molecules. The graphene oxide can effectively enhance the decontamination performance of the hydrogel. For stainless steel, ceramic, glass, and rubber surfaces, the decontamination rates of the hydrogel for 30min were 96.95%, 87.6%, 96.27%, and 74.5%, respectively. The decontamination effect was stable to temperature. For cement surfaces, the hydrogel could reach a maximum decontamination rate of 70.68% after 24h. The decontamination efficiency of hydrogel was affected by porosity, surface roughness, and graphene oxide addition. The characterization results of XPS, FT-IR, and SEM/EDS showed that the decontamination process of the composite hydrogel may involve surface wetting, ion diffusion, electrostatic attraction, and physical entanglement.

Study of the surface texture evolution and friction degradation in asphalt pavements during wear process

Study of the surface texture evolution and friction degradation in asphalt pavements during wear process

A molecular dynamics study on microscopic mechanism of nano-polished single crystal copper

Molecular dynamics simulations are performed to investigate the microscopic mechanism of diamond abrasive grain (DAG) polishing on the surface of single crystal copper (SCC). In this paper, the polishing parameters including the incident angle and the polishing force applied to the DAG are varied to analyze the surface morphology, friction and subsurface damage state of the workpiece. The polishing process on scratched SCC surface was also investigated. It is found that variations in the incident angle and the polishing force have significant effects on the swarf formation and internal structure of the workpiece. At small incident angle, unstable DAG motion and obvious friction fluctuations is observed. As the incident angle becomes larger, the sliding of the DAG on the workpiece surface becomes stable, and the friction force undergoes transition from the rapid growth to the stabilization phase. However, the fluctuation of dislocation density increases with the incident angle. As the polishing force increases, the sliding distance required to reach the peak of dislocation density becomes longer. In addition, the friction as well as the dislocation density show different characteristics on the scratched surface compared to the smooth surface.

Analysis of geometrical parameter sensitivity and mechanism of flow loss in exhaust volute based on particle swarm optimization

To investigated the mechanism of flow loss occurs in gas-turbine exhaust volute, comprehensive analysis was conducted based on the traces of parametric optimizations. An original volute was parameterized by depicting the core-part with 6 parameters. Concerning the coefficients of total pressure loss and static pressure recovery, the volute was optimized, as a start of the investigation, by Particle Swarm Optimization (PSO) to generate 56 exhaust volute designs and 8 geometric parameter traces. The geometry evolution history was fully recorded by these traces during the optimization. Based on this, parameter sensitivity analyses were conducted by single, double and K-means-clustering-based comprehensive parameters. Furthermore, partial dependence plot (PDP) and individual conditional expectation plot (ICEP) were applied to enhance the expression of parameter sensitivity. This enables the detailed discussion of the mechanisms of flow loss occurs in exhaust volute. The results demonstrate that the Particle Swarm Optimization (PSO) algorithm is highly effective for optimizing the exhaust volute. After six rounds of optimization with eight particles per round, the total pressure loss coefficient at the exhaust volute outlet was reduced by 35%, while the static pressure recovery coefficient increased by 79%. The sensitivity analysis reveals that geometric parameters exhibit varying degrees of influence on aerodynamic performance, with diffuser length being the most critical factor. Notably, a shorter diffuser, constrained by the same external dimensions, tends to result in lower flow losses. Flow loss within the collector accounts for 71.7% of the total loss, which can be attributed to surface friction and turbulent dissipation. The latter is primarily driven by turbulent viscous dissipation, predominantly occurring in the collector section. Additionally, the size of large-scale vortices in the curved parts of the diffuser and collector, which contribute to turbulent dissipation, as well as the ratio of the average flow velocity to circulation speed in the collector, which affects wall friction, are key factors in flow loss generation.

Investigating the Acoustic Behavior of Polyurethane Foam Reinforced with Clay Nanoparticles

Introduction: Disturbing noise can cause physical and mental illnesses among workers; for this reason, it is necessary to restrain it, especially in workplaces. Using sound-absorbing materials with suitable acoustic properties has been a growing trend in mitigating noise. This study aimed to improve the acoustic properties of polyurethane foam (PUF) as a sound absorber. Material and Methods: In the present study, PUF was synthesized with different percentages of clay nanoparticles (0 -1.2 wt.%), and then the Sound Absorption Coefficient (SAC) of the synthesized PUF was measured by the acoustic impedance tube in the frequency range of 63 to 6400 Hz according to the ISIRI 9803 standard. The morphology of the foam was also investigated by Scanning Electron Microscope (SEM) Results: The results showed that the addition of clay nanoparticles to PUF improved the sound absorption behavior of the samples, and the best sound absorption behavior was for PUF with 1.2% weight of nanoparticles at low frequencies (500-2600 Hz). This increase in the absorption coefficient can be due to the increase in the number and smaller size of the pores with the increase in the amount of nanoparticles in PUF. Conclusion: This study illustrates that the incorporation of clay nanoparticles into PUF at varying percentages results in an enhanced absorption coefficient. The presence of clay nanoparticles leads to a reduction in cell size and an increase in the number of pores, consequently enhancing surface friction. The absorption coefficient was observed to increase with the growing concentration of clay nanoparticles in PUF.

Towards understanding the surface friction in rotational-vibration assisted incremental sheet forming

Towards understanding the surface friction in rotational-vibration assisted incremental sheet forming

Effect of oxidation of End-of-Life Tire Rubber as Aggregate Substitute in Cement Mortars.

In this paper the possible use of end-of-life tire rubber as a substitute for aggregate in cement mortars was explored. The aim of this paper was to investigate the effect of rubber surface modification by acidic treatment on the final properties of mortars. In fact, through treatment with sulfuric acid at moderate concentrations, a significant improvement in rubber wettability and interaction with cement has been observed. The compressive strength of mortars containing 15%w treated rubber as a replacement of natural aggregate is comparable to those of standard mortars. This suggests that surface modification of rubber plays a very important role in the possible integration of end-of-life tire rubber in mortar and concrete. The results presented in this paper confirm that recycling in mortar and concrete is a promising way for improving rubber waste management and sustainable innovation in the construction industry.

An Empirical Model-Based Algorithm for Removing Motion-Caused Artifacts in Motor Imagery EEG Data for Classification Using an Optimized CNN Model.

Electroencephalography (EEG) is a non-invasive technique with high temporal resolution and cost-effective, portable, and easy-to-use features. Motor imagery EEG (MI-EEG) data classification is one of the key applications within brain-computer interface (BCI) systems, utilizing EEG signals from motor imagery tasks. BCI is very useful for people with severe mobility issues like quadriplegics, spinal cord injury patients, stroke patients, etc., giving them the freedom to a certain extent to perform activities without the need for a caretaker, like driving a wheelchair. However, motion artifacts can significantly affect the quality of EEG recordings. The conventional EEG enhancement algorithms are effective in removing ocular and muscle artifacts for a stationary subject but not as effective when the subject is in motion, e.g., a wheelchair user. In this research study, we propose an empirical error model-based artifact removal approach for the cross-subject classification of motor imagery (MI) EEG data using a modified CNN-based deep learning algorithm, designed to assist wheelchair users with severe mobility issues. The classification method applies to real tasks with measured EEG data, focusing on accurately interpreting motor imagery signals for practical application. The empirical error model evolved from the inertial sensor-based acceleration data of the subject in motion, the weight of the wheelchair, the weight of the subject, and the surface friction of the terrain under the wheelchair. Three different wheelchairs and five different terrains, including road, brick, concrete, carpet, and marble, are used for artifact data recording. After evaluating and benchmarking the proposed CNN and empirical model, the classification accuracy achieved is 94.04% for distinguishing between four specific classes: left, right, front, and back. This accuracy demonstrates the model's effectiveness compared to other state-of-the-art techniques. The comparative results show that the proposed approach is a potentially effective way to raise the decoding efficiency of motor imagery BCI.

Quantification analysis of high-speed train aerodynamics with geometric uncertainty of streamlined shape

Purpose This study aims to get a better understanding of the impact of streamlined high-speed trains (HSTs) with geometric uncertainty on aerodynamic performance, as well as the identification of the key parameters responsible for this impact. To reveal the critical parameters, this study creates a methodology for evaluating the uncertainty and sensitivity of drag coefficient induced by design parameters of HST streamlined shapes. Design/methodology/approach Bézier curves are used to parameterize the streamlined shape of HSTs, and there are eight design parameters required to fit the streamlined shape, followed by a series of steady Reynolds-averaged Navier–Stokes simulations. Combining the preparation work with the nonintrusive polynomial chaos method results in a workflow for uncertainty quantification and global sensitivity analysis. Based on this framework, this study quantifies the uncertainty of drag, pressure, surface friction coefficient and wake flow characteristics within the defined ranges of streamline shape parameters, as well as the contribution of each design parameter. Findings The results show that the change in drag reaches a maximum deviation of 15.37% from the baseline, and the impact on the tail car is more significant, with a deviation of up to 23.98%. The streamlined shape of the upper surface and the length of the pilot (The device is mounted on the front of a train’s locomotive and primarily serves to remove obstacles from the tracks, thereby preventing potential derailment.) are responsible for the dominant factors of the uncertainty in the drag for HSTs. Linear regression results show a significant quadratic polynomial relationship between the length of the pilot and the drag coefficient. The drag declines as the length of the pilot enlarges. By analyzing the case with the lowest drag, the positive pressure area in the front of pilot is greatly reduced, while the nose tip pressure of the tail is enhanced by altering the vortices in the wake. The counter-rotating vortex pair is significantly attenuated. Accordingly, exerts the impacts caused by geometric uncertainty can be found on the wake flow region, with pressure differences of up to 900 Pa. The parameters associated with the shape of the upper surface contribute significantly to the uncertainty in the core of the wake separation region. Originality/value The findings contribute to a better understanding of the impact of streamlined HSTs with geometric uncertainty on aerodynamic performance, as well as the identification of the key parameters responsible for this impact. Based on this study, future research could delve into the detailed design of critical areas in the streamlined shape of HSTs, as well as the direction of shape optimization to more precisely and efficiently reduce train aerodynamic drag under typical conditions.

The tribological behavior of Cu-based brake materials against Cr3C2-NiCr coated steel disks with varying roughness

A high coefficient of friction (COF) and low wear rate are expected in the braking system for high-speed trains. For this purpose, we prepared coated steel disks by spraying Cr3C2-NiCr powders and slid them against Cu-based powder metallurgy pins. Pin-on-disk tests showed a significant increase in the COF with the Cr3C2-NiCr coated disk (roughness of 1.0 µm) reaching 0.514, compared to 0.366 for the uncoated steel disk. Additionally, there was a notable reduction in wear loss of the brake material, with the coated disk losing only 0.0088g, while the uncoated disk lost 0.0760g.The lower adhesion between the coating and the pin material, combined with the abrasive action of the harder coating on the disk surface, helps maintain the friction surface flat and virgin, thus avoiding the formation of thick friction films and fatigue cracks. As a result, a higher and more stable COF with lower wear was achieved when the coated disk slid against the pins.

Rheological and Tribological Properties of Konjac Gum-Lecithin Composite System: Effect of Incorporation of Saliva and Friction Surface Properties.

This research explored the development of composite systems using konjac gum (KGM) and soy lecithin at concentrations of 1% KGM-0.01% lecithin and 1% KGM-0.2% lecithin. The study investigated the influence of both oral and artificial saliva on the rheological and tribological properties of these systems, as well as the lubrication on different friction surfaces with varying characteristics. It has been found that different friction surfaces exhibited distinct morphological features and roughness values, significantly impacting surface wettability when treated with saliva. The viscosity of KGM-lecithin composite systems increased slightly compared to KGM hydrogel. However, adding oral or artificial saliva led to a noticeable decrease in viscosity. Lecithin did not significantly alter the viscoelastic properties of KGM gel, but the incorporation of artificial and oral saliva introduced some changes. CLSM images showed that the stability and distribution of lecithin within the composite system varied with lecithin concentration and saliva type, with artificial saliva ensuring a stable and even distribution, while oral saliva caused aggregation and irregular distribution. Furthermore, the study found that the lubrication performance of the KGM-lecithin system was influenced by the properties of the friction surface, with hydrophilic rough surfaces providing superior lubrication compared to rough surfaces. The addition of lecithin enhanced lubrication across all tested surfaces, and artificial saliva surpassed oral saliva in reducing friction coefficients. These findings offer valuable insights into the potential use of KGM-lecithin composite systems as fat mimetics, particularly in enhancing lubrication for various applications.

Study on the Effects of CeO2 on the Micro-Structure and Wear Resistance of CuCrZr Plasma Cladding Coatings

The electromagnetic railgun, a novel kinetic energy weapon, has found utility in military operations due to its enhanced safety features and superior precision. This study investigates the enhancement of wear resistance in CuCrZr rails through the plasma cladding of CuCrZr-CeO2 coatings with a varying Cerium dioxide (CeO2) content. To enhance the wear resistance of the CuCrZr track, plasma cladding of CuCrZr-CeO2 coatings with varying CeO2 content was investigated. The impact of CeO2 content (0%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%) on the microstructure, phase composition, and mechanical properties of the CuCrZr coating was assessed using scanning electron microscopy (SEM), X-ray diffraction (XRD), EDS(Energy Dispersive Spectrometer) surface scanning, friction and wear tests, and hardness analysis. The findings indicate that a CeO2 content of 0.15% leads to a transition in the coating’s microstructure from columnar to equiaxed crystals, with the densest grain structure. Beyond 0.15% CeO2, pore defects in the coating increase, compromising mechanical properties. The coating containing 0.15% CeO2 exhibits optimal performance, with a hardness of 75.3, representing a 5.31% increase compared to CeO2-free CuCrZr coatings. Under a 10 N load, the friction coefficient decreases by approximately 17.9% to about 0.64. Moreover, the minimum wear mass is reduced by 44.7% to 3.87 mg. The aforementioned research findings hold immense importance in extending the lifespan of the electromagnetic railgun and improving its operational efficiency.

Inactivation of deposited bioaerosols on food contact surfaces with UV-C light emitting diode devices.

The airborne transmission of infectious diseases and bioaerosol-induced cross-contamination pose significant challenges in the food, dairy, and pharma industries. This study evaluated the effectiveness of 279 nm UV-C LED irradiation for decontaminating bioaerosols, specifically containing microorganisms such as Escherichia coli (C3040- Kanamycin resistant), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973), on food contact surfaces. Borosilicate glass, silicon rubber, and stainless steel (316L) surfaces were selected for experimentation for their usage in the food industry. A 50 µL cell suspension was aerosolized at 25 psi pressure using a 4-jet BLAM Nebulizer within a customized glass chamber and then deposited onto the surface of the coupons. The serial dilution approach was used for the microbial enumeration, followed by duplicate plating. With a low Root Mean Square Error (RMSE) and high R2 values, the biphasic kinetic model for UV-C inactivation curves of all three pathogens demonstrated the excellent goodness of fit parameters. At a UV-C dose of 6 mJ cm-2, glass surfaces showed the maximum microbial inactivation (i.e., 2.80, 3.81, and 3.56 log CFU/mL for E. coli, Salmonella, and P. fragi, respectively). Stainless steel and silicon rubber surfaces showed significant microbial inactivation, but log10 reductions observed were consistently lower than glass surface. Our research indicates that UV-C LEDs (279 nm) can effectively disinfect bioaerosols on food contact surfaces.IMPORTANCEFood safety is a major public health concern, with contaminated food causing serious illnesses. UV-C light, used for germicidal action, is effective in disinfecting surfaces and is not subject to the same strict legal restrictions as chemical disinfectants, simplifying compliance with food safety regulations. In this study, we evaluated the efficacy of UV-C (279 nm) LED systems for inactivation of surface-deposited bioaerosols of kanamycin-resistant Escherichia coli (C3040), Salmonella Enteritidis (ATCC 4931), and Pseudomonas fragi (ATCC 4973). The research outcomes can be used to develop UV-based surface disinfection systems to minimize the risk of foodborne illnesses and enhance safety in high-traffic food preparation areas.