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MXenes, a newly emerging class of layered two dimensional (2D) materials, are promising solid lubricants due to their 2D structure consisting of weakly-bonded layers with a low shear strength and ability to form beneficial tribo-layers. This work aims at evaluating for the first time MXenes lubrication performance and tribofilm formation ability on different metallic substrates (mirror-lapped Fe and Cu discs). After depositing MXenes via ethanol (1 wt%) on the substrates, pronounced differences in the resulting substrate-dependent frictional evolution are observed. While MXenes are capable to reduce friction for both substrates after the full evaporation of ethanol, MXenes lubricating effect on Cu is long-lasting, with a 35-fold increased lifetime compared to Fe. Raman spectra acquired in the wear-tracks of the substrates and counter-bodies reveal notable differences in the friction-induced chemical changes depending on the substrate material. In case of Fe, the progressive failure of MXenes lubrication generates different Fe oxides on both the substrate and the ball, resulting in continuously increasing friction and a poor lubrication effect. For Cu, sliding induces the formation of a Ti3C2-based tribofilm on both rubbing surfaces, enabling a long-lasting lubricating effect. This work boosts further experimental and theoretical work on MXenes involved tribo-chemical processes.

Three composite bronzes reinforced with steel dendrites from steels of different classes, which perform the function of a bearing surface in sliding friction, are studied. The chemical compositions of the dendrites and of the matrix are determined as a function of the heat treatment of bronze BrZhNOA 12-7-2-1. The fine structure of dendrites in bronze BrZhNKoA 9-4-1-1 is studied and the effect of the aging temperature in the intermetallic reinforcement of the dendrite with composition corresponding to maraging steel N23Yu1 is determined. The type of the crystal lattice of the dendrite is shown to affect substantially the tribological properties of bronze BrZhNKhA 12-9-3-1. © 2022, Springer Science+Business Media, LLC, part of Springer Nature.

Published research about brake shoe temperature assessments and the influences of temperature dependent brake Coefficient of friction (CoF) on train braking performance do not consider detailed train dynamics. This paper addresses this research gap by combining a brake shoe temperature model with a detailed Longitudinal Train Dynamics (LTD) model. A simplified one-dimensional (1D) Finite Element brake shoe temperature model was developed. Studies were conducted to assess brake shoe temperatures during cyclic air brakes and single-occurrence air brakes. Results show brake shoe temperatures at different positions of the train can be very different due to brake characteristics variations. During case studies, temperature dependent brake CoF increases train braking distances by 10.2 and 6.6% on down grade and flat tracks respectively. Emergency brake cases have the highest increases of brake distances by 11.3% on down grade tracks.

This study provides guidelines for the industrial machining of wood-plastic composites, focusing on their behaviour under friction, specifically when friction is caused by sliding contact with cemented carbide. Using the response surface method (RSM) to explore the correlation between the friction coefficient and the wood-plastic composite type, loading force, and reciprocating frequency, a series of frictional tests were performed. The significant contributions of each factor and their two-factor interactions were determined by analysis of variance (ANOVA), with a significance level of 5%, while trends in the variation of the friction coefficient were investigated by using a response surface methodology. The wood-plastic composite types had the greatest impact on the friction coefficient, followed by loading force and reciprocating frequency. A mathematical model (CoF = −0.10 + 0.09ω−0.02f+0.01Fn−0.01ωf+2.38×10−3ωFn−2.00×10−4Fnf+0.11ω2+2.96f2−1.04×10−4Fn2) was developed to accurately predict changes in the friction coefficient during machining of such composites. According to the results of the optimisation, wood-plastic composite with polypropylene should be machined with high-speed cutting, whereas those with polyethylene and polyvinyl chloride are recommended for low-speed machining, so as to ensure the lowest friction coefficient. Validerad;2023;Nivå 2;2023-06-30 (joosat);Funder: National Natural Science Foundation of China (31971594); Natural Science Foundation of the Jiangsu Higher Education Institutions of China (21KJB220009); the SelfMade Experimental and Teaching Instruments of Nanjing Forestry University in 2021 (nlzzyq202101); Technology Innovation Alliance of Wood/Bamboo Industry (TIAWBI2021-08); International Cooperation Joint Laboratory for Production, Education, Research and Application of Ecological Health Care on Home Furnishing

The seismic stability of geosynthetic structures incorporating soil-geomembrane interfaces depends largely on their response to dynamic loads caused by earthquakes or traffic. The present study investigates the dynamic shearing response of sand-smooth geomembrane interface through fixed block-type shake table tests. The influence of dynamic loading parameters, like sliding velocity, loading frequency, normal stress, displacement amplitude and the number of cycles, and relative density of sand on the shearing behavior of the sand-geomembrane interface, are examined. Results show that the peak cyclic shear stress is significantly influenced by normal stress, shear displacement amplitude, loading cycles, and relative density of sand. The dynamic coefficient of friction of the sand-geomembrane interface displays an increasing trend with an increase in loading frequency, shear displacement amplitude, and relative density of sand but decreases for the rest of the considered parameters. The shape of the hysteresis loops is dependent on the normal stress and displacement amplitude. The dynamic coefficients of friction are also compared with the corresponding values under static conditions. The results from the present study emphasize the importance of considering the design basis value of the dynamic coefficient of friction for each parameter during the design stage of geosynthetic structures involving sand and geomembrane.

The use of vegetable oils as lubricants in automobiles is rapidly increasing due to the prevailing environmental aspects. Vegetable oils are also suitable for other applications because they come from renewable and sustainable natural sources and have high biodegradability and low toxicity. Nanoparticles have been extensively investigated for a long time as potential performance improvers of traditional antifriction and antiwear additives because of their inherent properties such as size and shape. The primary aim of the study is to investigate the use of jatropha oil mixed with graphite, molybdenum disulfide (MoS2), and titanium dioxide (TiO2) nanoparticles as a nanoparticle biolubricant. The nanoparticles of graphite, molybdenum disulfide, and titanium dioxide are added in varying weight percentages to jatropha oil and a tribological analysis is carried out using a pin-on-disc tribometer. The analysis is focused on tribological quantities, such as coefficient of friction, wear volume, and frictional force. The experiment was carried out for 5 minutes under varying loads at different disc speeds. At an optimum concentration of nanoparticles, the coefficient of friction, frictional force, and the wear rate were found to have the lowest values, but when the level of nanoparticles increases above the optimum level, the friction coefficient and wear rate seem to be increased. The pin-on-disc experiments revealed that nanographite powder mixed in jatropha oil gives better tribological performance than the other two tested nanopowders. Subsequently, multiple regression models are developed using input and output variables. A non-linear fit between the response and the corresponding significant parameters is considered.

In this present study the results for the tribo-testing of AISI 4140 steel specimens under fly ash nanoparticles based lubricating oils were interpreted. The results and graphical representation of coefficient of friction (COF) response for all the trails conducted under different sliding distance, sliding speed, load and concentration percentage of fly ash nanoparticles are presented this paper. The variation of COF with respect to sliding distance (SD) in each case was studied and discussed. Interpretation of the wear mechanism for the alloy steel with nano fly ash based lubricant was performed, using spectroscopy of the worn out sample pins of the AISI 4140 steel. The spectrum showed the formation of tribofilm due to the presence of oxygen in abundance, confirmed by the Scanning Electron Microscopy (SEM) and Electron Dispersive Spectroscopy (EDS) at all spectrums. Formation of tribofilm is the cause of the reduction in the wear in fly ash nanoparticles based lubricants. EDS results at the worn tip of the AISI 4140 sample has been discussed.

The mechanical properties of Al-Si alloys have been investigated. Abrasion wear resistance is an important analysis being used in various applications so there are many laboratory testing methods to determine it. In this article, we've looked at one of the ways to determine wear resistance using a scratch tester as a relatively easy, efficient, and fast test method. Materials used in the tests were: Al-Si (Al 94.30; Si 2.24, Fe 0.84) alloy. The coefficient of friction and wear of the samples were determined both by the methods of testing the wear and by investigating them in correlation with their mechanical properties.

Circular economy is still an imaginary field. In this manuscript, mild steel material is used to evaluate the coefficient of friction (COF) of cotton fabric. COF is evaluated to facilitate circular economy of textile industries. Scanning electron microscope (SEM), optical profilometer, mechanical profilometer and tribometer were used for AISI 52100 steel balls and cotton textile waste. The fabric surface was found distorted and damaged due to joggling, bobs, jerks, and pills surface defects. These defects produced due to physical and chemical treatments. The average coating surface roughness parameters were Rmax (0.35 µm), Rz (0.50 µm), and Rp (0.45). The dynamic coefficient of friction (COF) values was found 0.21 to 0.12 in warp and 0.17 to 0.10 in weft directions. The tensile strength and hardness values of mild steel 2600 MPa and 65 on HRC, respectively proved that metallic surface is smooth and soft. The smaller COF values and soft metallic surface produced low grip and cutting resistance due to damaged and distorted textile wastes. Based on COF values, deformation, wear and morphology evaluations, the mild steel machinery parts could be used operationally for recycling of textile wastes. for surface alterations of textile machinery parts. Furthermore, damaged, and distorted post-consumer textile wastes required hard, high strength and well finished machinery parts surfaces for its recycling.

Purpose The involvement of wear, friction and lubrication in engineering systems and industrial applications makes it imperative to study the various aspects of tribology in relation with advanced technologies and concepts. The concept of Industry 4.0 and its implementation further faces a lot of barriers, particularly in developing economies. Real-time and reliable data is an important enabler for the implementation of the concept of Industry 4.0. For availability of reliable and real-time data about various tribological systems is crucial in applying the various concepts of Industry 4.0. This paper aims to attempt to highlight the role of sensors related to friction, wear and lubrication in implementing Industry 4.0 in various tribology-related industries and equipment. Design/methodology/approach A through literature review has been done to study the interrelationships between the availability of tribology-related data and implementation of Industry 4.0 are also discussed. Relevant and recent research papers from prominent databases have been included. A detailed overview about the various types of sensors used in generating tribological data is also presented. Some studies related to the application of machine learning and artificial intelligence (AI) are also included in the paper. A discussion on fault diagnosis and cyber physical systems in connection with tribology has also been included. Findings Industry 4.0 and tribology are interconnected through various means and the various pillars of Industry 4.0 such as big data, AI can effectively be implemented in various tribological systems. Data is an important parameter in the effective application of concepts of Industry 4.0 in the tribological environment. Sensors have a vital role to play in the implementation of Industry 4.0 in tribological systems. Determining the machine health, carrying out maintenance in off-shore and remote mechanical systems is possible by applying online-real-time data acquisition. Originality/value The paper tries to relate the pillars of Industry 4.0 with various aspects of tribology. The paper is a first of its kind wherein the interdisciplinary field of tribology has been linked with Industry 4.0. The paper also highlights the role of sensors in generating tribological data related to the critical parameters, such as wear rate, coefficient of friction, surface roughness which is critical in implementing the various pillars of Industry 4.0.

This study investigates the influence of heating rate on the tribological and corrosion properties of 52100 bearing steel samples consolidated via spark plasma sintering. The consolidation was conducted at different heating rates of 50, 100, 200, 300, and 400 °C/min and the thermomechanical properties of the resulting samples were characterized. Ball-on-disc tribological tests and electrochemical techniques were used to evaluate the wear and corrosion resistance, respectively. The results showed that an increased heating rate positively affects the thermomechanical and tribological properties of 52100 bearing steel. The sintered samples exhibited a low coefficient of friction (between 0.4 and 0.56) and a low wear rate (between 1.4 and 1.8 × 10−6 mm3/Nm) at heating rates between 100 and 400 °C/min. Furthermore, the corrosion resistance of the samples gradually drops above the heating rate of 100 °C/min. The samples can be ranked in the order of decreasing corrosion resistance thus: 100 > 200 > 300 > 400 > 50 °C/min. The improved corrosion resistance of the sample sintered at 100 °C/min can be attributed to its refined crystal size and high density.

In order to improve the power selection of the drive unit for the shredding machines,theauthors determine the values of friction coefficients used in the cutting force models. These values consider the friction between steel and such wood-based materials as chipboard, MDF and OSB. The tests concern laminated and non-laminated external surfaces and surfaces subjected to cutting processes. The value of the coefficient of friction for the tested materials is in the range: for the static coefficient of friction 0.77-0.33, and for the kinetic coefficient of friction 0.68-0.25. The highest values of the static and kinematic coefficient of friction were recorded for MDF (non-laminated external surface) and they were equal respectively: 0.77 and 0.68. In turn, thesmallest values of the discussed coefficients were recorded for chipboard (laminated external wood-base surface), which were at the level of 0.33 and 0.25, resp.

The coefficient of friction plays a key role in the metalforming process, especially at high temperatures, to reduce the required energy for material forming. In this study, compression ring test w...

Aluminium alloys and their composites are often used in aerospace, automobile and biomedical applications. However, mechanical and surface properties of those alloys have not reached up to the expectation. This investigation focused to improve the wear resistance properties along with mechanical and surface properties of aluminium matrix composites. Here, novel aluminium matrix nanohybrid composites were developed using titanium oxide and graphite as reinforced via powder metallurgical route. The sintered samples were analysed by different tests such as, hardness, surface roughness, wear tests and other structural analyses. The obtained results showed that some new compounds formed during sintering were responsible for improved mechanical and surface properties for different applications. The wear test showed that there was rapid worn out of graphite from the composites having aluminium content more than 50 wt% due to the higher content of graphite (10 and 20 wt%, respectively). In addition, due to the increase of porosity in the different hybrid composites, there was an increase in coefficient of friction observed in some materials. The aluminium nanohybrid composite having 40 wt% titania and 10 wt% graphite showed best results compared with others. Therefore, the optimized hybrid composites with proper sintering condition would significantly help to get suitable structural, mechanical as well as tribological properties for many advanced applications.

Adhesion and friction of soft solids on hard surfaces are the important properties for a variety of practical applications. In the present study, Coulomb's law of friction is used for characterizing adhesive friction as well as normal stress-dependent dynamic friction of a gelatin hydrogel on a fixed glass surface. The experimental data, concerning normal stress-dependent dynamic friction of different shear velocity, are obtained from literature. It is observed that both components of friction increase with shear velocity. More importantly, the scaling law shows that adhesive stress varies almost linearly with corresponding coefficient of friction of the hydrogel. A dynamic friction model is also used to analyze the same experimental data to predict a negative normal stress at which dynamic friction reduces to zero, and this result matches closely with the experimental value.

The subject of the experiments was the tribological properties of typical brake pads and disc characteristics. For the experiment was used Grey Cast Iron brake disc and semi metallic, low steel quantity and ceramic brake pads. The breaking process was imitated. The experiment was conducted at 0.75, 1.25 and 1.76 m/s sliding speed using 0.85 MPa contact pressure. The experiments lasted 10 minutes. The results of the experiments showed that best tribological characteristics have ceramic brake pads, despite the fact that brake disc temperature rapidly increase the with ceramic brake pads, but the friction coefficient (and braking torque) was the best. Semi metallic and low steel braking pads had very similar friction coefficient values, but wear and disc temperature values were more dissimila

This research article deals with the comparative performance analysis of the nanocomposite SiC-Ni-P coating on the edge and chamfer parts of the brake pad. The coating is used to provide a smooth s...

Humidity can affect the bulk behavior of fine hygroscopic powders at multiple levels and fewer mitigation approaches are presently available to counter its adverse effects. This work reports these ...

The effect of dispersed particles of lamellar molybdenum, tungsten and vanadium oxides on the lubrication properties of mineral oil was investigated. It is shown that in the presence of particles of hexagonal molybdenum oxide the coefficient of friction falls two-fold (from 0.08 to 0.04) exhibiting further decrease under high mechanical load, i. e. molybdenum oxide behaves as an adaptive lubricant. The intercalation of benzotriazole into molybdenum oxide ensures additional reduction of mechanical wearing due to suppressing the tribocorrosion.

HIPS-g-MAH compatibilizer and the other three compatibilizers were prepared and added to the polyamide 66/polyphenylene oxide (PA66/PPO) alloy. The FT-IR spectra showed that the maleic anhydride (MAH) had successfully undergone grafting on the high impact polystyrene (HIPS). The effect of the MAH ratio in the HIPS-g-MAH compatibilizer, the HIPS-g-MAH compatibilizer weight ratio, and the PA66/PPO ratio on the mechanical properties of PA66/PPO alloy was systematically studied. The results showed that the PA66/PPO alloy possessed the optimal mechanical properties when the HIPS-g-MAH compatibilizer weight ratio was 7% and the MAH ratio in HIPS-g-MAH compatibilizer ranged 4% ~ 8%. The fracture morphologies of PA66/PPO alloy with different HIPS-g-MAH compatibilizer weight ratios were characterized by scanning electron microscope (SEM). The PA66/PPO alloy without HIPS-g-MAH compatibilizer showed a typical brittle fracture. The mechanical properties of PA66/PPO alloys with the HIPS-g-MAH compatibilizer were improved. In addition, the crystallization temperature of PA66/PPO alloy decreased with the increase in the HIPS-g-MAH compatibilizer weight ratio. The PA66/PPO ratio also played an essential role in the PA66/PPO alloy properties. The coefficient of friction and wear rate both increased with the increase in the PPO ratio.

Some physical properties of palmyrah fruit were investigated in this study. The average values of major, medium, minor and geometric mean diameters of fresh whole palmyrah fruit were 11.54,10.45, 9.85 and 10.64 cm respectively at 47.34 % (w.b) moisture content whereas that of palmyrah nut were 8.59, 7.35, 4.99 and 6.79 cm respectively at 8% (w.b) moisture content. Sphericity, surface area and aspect ratio were found to be 91.94%, 359.17 cm2 and 0.90 for fruit and whereas that of nut were 79.19%, 145.16 cm2 and 0.86 respectively. The average mass of the individual palmyrah fruit and nut was 927.78 and 248.10 g whereas bulk density was 525.92 and 693.0 kg/m3 respectively. The coefficient of static friction on mild steel, glass and plywood surfaces were 0.27, 0.21 and 0.25 for palmyrah fruit and 0.36, 0.28 and 0.27 for nut respectively. The angle of repose of palmyrah fruit and nut were 30.77 and 44.03 respectively.

In this research work, the interaction of aluminum alloy (6061) and EN-31 steel is examined, and interaction is studied on the basis of tribological outcomes under dry sliding conditions at various ranges of temperature. The extrusion process is actually an intricate process, which depends on environmental temperature, sliding velocity with respect to the mating part, the type of external shape, wear and coefficient of friction. Here, variables which directly or indirectly influence the interactions are designed for this system in such a manner that the results can be co-related with another system that has equivalent working condition as there in hot forming and cold forming (up to 250°C) of material interactions. The current work is done on a pin which slides on a disc of aluminium alloy 6061 and EN-31 steel set-up. Experiments are carried out under different conditions by using the design of experiments (DoE) for each case. In the first case (Case-I), the disc is steel and the aluminum alloy works as a pin. In the second case (Case-II), the disc is aluminum alloy and steel works as a pin. Henceforth, frictional coefficient and difference in the weight or wear (volume loss) before and after experiment is achieved. Finally, experiments are designed with the help of design tool to optimize the results and execute the different parameters by involving the analysis of variance . Lower wear volume loss is observed in a steel disc compared to the aluminium alloy pin at room temperature.

The effect of the apex angle of triangular oil pockets created on a disc surface on friction was studied. Experiments were carried out using an Optimol SRV5 tribotester equipped with a pin-on-disc module under unidirectional lubricated sliding. Both the sample and counter sample was made of steel of 45 Hardness Rockwell C (HRC) hardness. Only 1 ml of oil was put to the inlet side of the contact area at the beginning of each test. All textured surfaces had the same pit-area ratio and an average depth of dimples. Oil pockets were positioned in the spiral array. It was found that the effect of the apex angle of triangular dimples on friction reduction was important. When the normal load was lower, the smallest coefficient of friction was achieved for the sliding pair with a disc apex angle of 60°. Under a larger normal load, a higher apex angle corresponded to a higher coefficient of friction.

Flexographic technology usage is increasing in recent years. Predicted growth in the technology usage intensifies the demand for improved quality. It is expected that flexographic printing will achieve greater results than ever before. Since this technique is used in the printing of shrink sleeve packaging, it is imperative to meet the technical and economic requirements of the shrink sleeve product. This is primarily to ensure gliding of the white printing material. The amount of white should be as small as possible, making the sliding of the material optimal and the quality of the print better. Therefore, the quality of the printing was measured by changing the conditions of slippage and white color. This research has established a correlation between the thickness of the white layer and the reduction of print quality over thin lines.

Purpose The purpose of the present paper aims to, study the coefficient of friction and wear behavior of nickel based super alloys used in manufacturing of gas and steam turbine blades. In present paper, parametric study focuses on normal load, dry sliding velocity and contact temperature influence on coefficient of friction and wear of a nickel based super alloy material. Design/methodology/approach Experimental investigation is carried out to know the effect of varying load at constant sliding velocity and varying sliding velocity at constant load on coefficient of friction and wear behavior of nickel based super alloy material. The experiments are carried out on a nickel based super alloy material using pin on disk apparatus by load ranging from 30 N to 90 N and sliding velocity from 1.34 m/s to 2.67 m/s. The contact temperature between pin and disk is measured using K-type thermocouple for all test conditions to know effect of contact temperature on coefficient of friction and wear behavior of nickel based super alloy material. Analytical calculations are carried out to find wear rate and wear coefficient of the test specimen and are compared with experimental results for validation of experimental setup. Regression equations are generated from experimental results to estimate coefficient of friction and wear in the range of test conditions. Findings From the experimental results, it is observed that by increasing the normal load or sliding velocity, the contact temperature between the pin and disk increases, the coefficient of friction decreases and wear increases. Analysis of variance (ANOVA) is used to study the influence of individual parameters like normal load, dry sliding speed and sliding distance on the coefficient of friction and wear of nickel based super alloy material. Originality/value This is the first time to study effect of contact temperature on the coefficient of friction and wear behavior of nickel-based super alloy used for gas and steam turbine blades. Separate regression equations have been developed to determine the coefficient of friction and wear for the entire range of speed of gas turbine blades made of nickel based super alloy. The regression equations are also validated against experimental results.

In dry sliding, the coefficient of friction depends on the material pair and contact conditions. If the material and operating conditions remain unchanged, the coefficient of friction is constant. Obviously, we can tune friction by surface treatments, but it is a nonreversible process. Here, we report active control of friction forces on TiO2 thin films under UV light. It is reversible and stable and can be tuned/controlled with the light wavelength. The analysis of atomic force microscopy signals by wavelet spectrograms reveals different mechanisms acting in the darkness and under UV. Ab initio simulations on UV light-exposed TiO2 show a lower atomic orbital overlapping on the surface, which leads to a friction reduction of up to 60%. We suggest that photocontrol of friction is due to the modification of atomic orbital interactions from both surfaces at the sliding interface.

This work attempts to evaluate the correlation between the roughness parameters and different standardized methodologies for determining the coefficient of friction of ceramic floor tiles. Eight different types of ceramic tiles were evaluated, and each one was characterized for their coefficient of friction/slip resistance in accordance with the standards NBR 13818, ANSI A137.1, and AS 4586. The surfaces were also characterized in relation to surface roughness by means of contact profilometry. The measured friction and roughness parameters were correlated by means of analysis of variance. The results showed a correlation tendency according to a third-degree equation for tests performed in wet conditions. The study results showed that the roughness parameters influence the coefficient of friction with a confidence level of 95%. Considering the safe values indicated for the respective standards for the evaluated methods, a Rz value of 25 μm ensures that a tested surface can be considered safe in a wet-condition test, regardless of the method used to determine the coefficient of friction.

Summary of the scientific communication presented in the 11th Iberian Conference on Tribology IBERTRIB2022, held during 6 - 8 October 2022 in Setúbal, Portugal, Improvements regarding durable lubrication together with minimized wear are mandatory for obtaining long-term, functioning metallic joint prostheses. For this goal, CoCr surface was functionalized with Graphene Oxide (GO), characterized by FTIR and XPS, and tested at tribocorrosion. Deposition of graphene oxide was carried out by consecutive steps: alkalinization of CoCr; intermediate coupling via 3-aminopropyltriethoxysilane (APTES) which was cured at 45 °C for 24 h; and final assemble of GO layers at 60 °C for 24 h upon exposure with silane-coated CoCr. FTIR displayed C=C band confirming the assembly of GO on silane-coated CoCr surfaces. XPS elucidated reaction between primary amines of APTES and epoxy groups of GO, free -OH groups in APTES and carboxyl groups in GO, and reaction between APTES primary amines and -OH from carboxyl groups of GO. COF values for GO incubated on silane-coated CoCr disks show stationary values near 0.2. CoCr surfaces in as-reception state show higher COF values increasing at longer testing times.

Summary of the scientific communication presented in the 11th Iberian Conference on Tribology IBERTRIB2022, held during 6 - 8 October 2022 in Setúbal, Portugal, The effect of normal load and rotational rate on the coefficient of friction (COF) of CoCr sliding against alumina was evaluated using a pin on disk tribometer. Tribological tests were carried out by using CoCr disks of 38 mm diameter and alumina balls of 6 mm diameter as counterpart (pin). An aqueous solution containing 3g/L of HA, concentration equivalent of that found in the synovial fluid, was used as lubricant and it was in continuous recirculation throughout the test. The COF values for two normal loads, 1N and 5N, and two rotational rates, 60 rpm and 120 rpm, have been obtained for a constant sliding distance of 500 m. The tribological tests were performed in duplicate in order to verify the reproducibility of the results. The results show that the COF varies with the load and with the rotational rate, so that, for the same load, the COF increases as the rotational rate decreases. This effect is more significant at lower loads. Meanwhile, the COF values are higher for loads of 1N than for 5N regardless of the rotational rate. The wear tracks were observed by optical microscopy and the images revealed the widest tracks at 5N and 60 rpm.

Medical device-related pressure ulcers (PUs) (injuries) are a subclass of PUs, associated with pressure and/or shear applied by a medical device onto the skin. Clinical application of a cyanoacrylate liquid skin protectant (CLSP) under the contours of skin-contacting medical devices to shield an intact skin from the sustained mechanical loads that are applied by medical devices is a preventative option, but no computer modelling work has been reported to assess the biomechanical efficacy of such interventions. Here, we investigated the biomechanical protective effect of a polymerised cyanoacrylate coating using three-dimensional, anatomically realistic finite element models of the ear with oxygen cannula and the mouth with endotracheal attachment device, informed by experimental studies. We have compared tissue stress exposures under the devices at these facial sites between conditions where the cyanoacrylate skin protectant has been applied or where the device was contacting the skin directly, without the shielding of the cyanoacrylate coating. The CLSP considerably reduced the skin stress concentration levels and overall tissue stress exposures under the aforementioned medical devices. This demonstrates strong biomechanical effectiveness of the studied cyanoacrylate-based skin protectant in prevention of facial medical device-related injuries at small, curved and thereby difficult to protect facial sites.

The surface dynamic and static coefficient of friction of yarns is one of the most important means of characterizing the surface structure of yarns and can provide an important basis for yarn perfo...

The tribological properties of SnO2 nanofluids were investigated using ball-on-plate reciprocating sliding wear tests. It was found that the coefficient of friction was reduced by 34.9% using 3 wt% SnO2 nanoparticles. The wear width and wear depth were reduced by 42% and 50.1%, respectively, using 2 wt% SnO2 nanoparticles. In the orthogonal tests, the frequency had the greatest influence on the friction and wear loss. Additionally, the optimal working conditions were a normal load of 50 N, a motion frequency of 1 Hz, and a surface roughness of 500–600 nm. Additionally, the excellent tribological performance of SnO2 nanofluids could be attributed to the formation of a tribo-film with a low shearing resistance due to the oleic acid and a protective layer due to the embedment of SnO2 nanoparticles.

The effects of the coefficient of friction and coefficient of restitution on the static packing characteristics of a polydisperse spherical pebble bed are numerically investigated using the discrete element method. Several important static packing characteristics under different coefficients of friction and restitution are presented and discussed. The results show that the coefficients of friction and restitution impose opposite effects on the packing heights and global packing factor. Neither the coefficient of friction nor restitution affected the oscillation width of the wall, whereas their effects are primarily reflected in the oscillation amplitude of the radial local packing factor and the axial local packing factor distribution at the top of the pebble bed. In both the contact force distribution and coordination number distribution, a left-shifted phenomenon appearing as the coefficient of friction occurred, and only the magnitude of the maximum frequency is affected when the coefficient of restitution changed from 0.1 to 0.9. In all simulation cases, the effects of the coefficients of friction and restitution are similar to that of cross-impact.

Objective: The aim of this in vitro study was to evaluate the changes in friction between orthodontic brackets and archwires coated with aluminum oxide (Al2O3), titanium nitride (TiN), or chromium nitride (CrN). In addition, the resistance of the coatings to intraoral conditions was evaluated. Methods: Stainless steel canine brackets, 0.016-inch round nickel-titanium archwires, and 0.019 x 0.025-inch stainless steel archwires were coated with Al2O3 TiN, and CrN using radio frequency magnetron sputtering. The coated materials were examined using scanning electron microscopy, an X-ray diffractometer, atomic force microscopy, and surface profilometry. In addition, the samples were subjected to thermal cycling and in vitro brushing tests, and the effects of the simulated intraoral conditions on the coating structure were evaluated. Results: Coating of the metal bracket as well as nickel-titanium archwire with Al2O3, reduced the coefficients of friction (CoFs) for the bracket-archwire combination (p < 0.01). When the bracket and stainless steel archwire were coated with Al2O3, and TiN, the CoFs were significantly lower (0.207 and 0.372, respectively) than that recorded when this bracket-archwire combination was left uncoated (0.552; p < 0.01). The friction, thermal, and brushing tests did not deteriorate the overall quality of the Al2O3, coatings; however, some small areas of peeling were evident for the TiN coatings, whereas comparatively larger areas of peeling were observed for the CrN coatings. Conclusions: Our findings suggest that the CoFs for metal bracket-archwire combinations used in orthodontic treatment can be decreased by coating with Al2O3, and TiN thin films.

This article presents the mechanical, physical, and tribological properties of the boron carbide (B4C) reinforced epoxy matrix composites (BEMCs). The BEMC samples were prepared with various B4C concentration of 0%, 1%, 2%, 3%, and 5%. B4C particles were treated with a silane coupling agent to ensure efficient adhesion with epoxy. The influence of a range of parameters (particle loading, sliding speed, sliding distance, and normal load) on the wear and friction behavior of BEMCs were evaluated by conducting wear tests under dry sliding conditions on a pin-on-disc wear test set-up. The addition of B4C to the epoxy polymer improved the wear resistance of the composites. Maximum wear resistance and coefficient of friction were observed for the composite with the highest percentage of B4C (5%). The specific wear rate was reduced on increasing load and sliding distance and increased with the sliding velocity. Mechanical properties including compression strength, flexural strength, and impact energy, along with physical properties such as density and hardness, were also evaluated. B4C particles improved the hardness, density, flexural and compression strength, and impact resistance of the composites. Scanning electron microscope (SEM) analysis of the worn-out surfaces and flexural fractured surfaces was carried out to predict the possible wear and fracture mechanisms. Micro-ploughing, abrasion, and adhesion were the wear mechanisms in BEMCs. Under the flexural loads, particulate de-bonding, pull-out, and brittle fracture of the matrix were the governing failure mechanisms.

According to the requirements of the “Rules for industrial safety of cranes”, anti-theft devices must ensure that cranes under the influence of wind force stop at any point on the track, including at the junction of rails connected by side strips. Various types of anti-theft crane devices recommended for use have a number of disadvantages. Thus, the supply of anti-theft crane devices made in the form of lever grips interacting with the rail head with mechanisms for disengaging and converging grippers with electromechanical, electromagnetic, hydraulic or pneumatic drives complicates their design. There are also known anti-theft crane devices, in which the stopping of cranes on a rail track is carried out by a locking eccentric interacting with the surface of the rail head. The reliability of such devices is insufficient, since, due to the constant force of the spring, the adhesion force of the eccentric to the rail does not depend on the changing wind force. The paper proposes the basics of calculating the anti-theft crane device, representing the kinematic connection of two mechanisms – eccentric and thick-borne, which allows to solve a number of the above problems.

Purpose This study aims to develop the Al-Si-Mg metal matrix composite, reinforced distinctly with lime stone powder (LSP; 12% by weight) and Al2O3 (12% by weight), and compare their mechanical properties and tribological performance. Design/methodology/approach The composites are fabricated through stir casting process. In view of the previous work, the Al-LSP composite with LSP reinforcement (12 Wt.%) shows enhanced mechanical properties and tribological performance, as compared with other weight percentages. Findings Though the Al-LSP composite is less expensive, it shows similar hardness, tensile strength and specific strength, when compared with Al- Al2O3 composite. However, the Al-LSP composite exhibits significant enhancement of above three properties, when compared with Al-Si-Mg metal. The systematic factorial design of experiments is obtained through Taguchi OA [L9]. The tribological performance is estimated through wear rate (WR-mm3/m) and coefficient of friction (CF) by varying the operating parameters of sliding distance (SD), load (L) and sliding velocity (SV). According to ANOVA results, the optimal condition of WR for all the tested materials is L1SD3SV1. Further, the optimal condition of CF is L1SD1SV3 for Al-LSP and Al-Si-Mg metal, while L2SD3SV2 is for Al-Al2O3 composite. The regression equation predicts the measured experimental values within error band of ± 8 percentage. Originality/value A comparison of two composite materials (Al-LSP and Al-Al2O3) with same weight fractions (12%) shows almost same trend in both the mechanical and tribological testing process. However, the developed Al-LSP composite exhibited better properties than the Al-Al2O3 and Al-base. Therefore, Al-LSP can be suggested for automotive applications (i.e., connecting rod, cylinder liners, camshaft) and structural applications (such as frames, over hanging supports), without compromising in desirable original with properties of constituents in the new material, which is achievable for looking to the end uses.

The present study has investigated the role of the addition of TiC nanoparticles on the microstructural, mechanical, physical, and metallurgical properties of the Cu-TiC nanocomposites. A Powder metallurgy route was used to fabricate the samples. Cold compaction of powders was done at 480 MPa which was followed by sintering at 950°C. Wt.% of TiC was varied from 0% to 20%. A Pin-On-Disc tribometer was used to carry out the wear and friction tests. SEM and EDS techniques were used to explicate the morphology and microstructures of worn surfaces and to comprehend the underlying wear mechanism. The fabricated samples were investigated against the applied normal load (10, 20, and 30 N), sliding speed (0.5, 1.0, and 1.5 m/s), and sliding distance (900, 1800, and 2700 m). The results revealed that the Hardness and tensile strength were improved by 88.76% and 37.26% respectively due to the addition of TiC and were maximum for Cu-20%TiC while the relative density shows the reverse trend. Further, it was found that wear resistance and coefficient of friction were improved by 87.18% and 51.85% respectively as a function of nano-TiC content. The presence of oxide layers and mechanically mixed layers are detected from worn surface analysis which modulates the tribological behavior of the contact.

In order to improve the friction and wear properties of Cu10Al–MoS2 coating, the addition of CeO2 is one of the present research hot spots. In this work, Cu10Al–MoS2 coatings with different CeO2 mass fractions were successfully fabricated on Q235 steel using a laser cladding. The microstructure and phase compositions of obtained coatings were analyzed using an ultra-depth of field microscope and X-ray diffraction, respectively. The friction-wear test was carried out under oil lubrication using a ball-on-disk wear tester, and the effects of CeO2 mass fraction on the microstructure, hardness, and friction-wear properties were studied, and the wear mechanism was also discussed. The results show that the laser cladded Cu10Al–MoS2 coatings with the different CeO2 mass fractions were mainly composed of Cu9Al4, Cu, AlFe3, Ni, MoS2, and CeO2 phases. The Vickers-hardness (HV) of Cu10Al–8MoS2–3CeO2, Cu10Al–8MoS2–6CeO2, and Cu10Al–8MoS2–9CeO2 coatings was 418, 445, and 457 HV0.3, respectively, which indicates an increase in hardness with the increase of CeO2 mass fraction. The average coefficients of friction (COF) and wear rates decrease with the increase of CeO2 mass fraction, presenting the outstanding friction reduction and wear resistance performances. The wear mechanism of Cu10Al–MoS2 coatings is changed from abrasive wear with slight fatigue wear to abrasive wear with the increase of CeO2 mass fraction.

Materials based on partially stabilized zirconia (ceramics and crystals) are distinguished by high values of mechanical strength, crack resistance, hardness, corrosion resistance, low coefficient of friction when operating in tandem with most metals, which makes them promising materials for a wide tribotechnical application in highly loaded friction units. An example of such a unit is the die mechanism, which is an integral part of the drawing die tool in the cable industry. These hard precision tools (drawing dies or wire dies) actually determine the ultimate success in the wire drawing process.

The possibility of introduction of antifriction and wear-resistant modifying agents into the matrix of a composite nickel-phosphorus coating to obtain effective composite coatings, is considered. The analysis of the possible influence of modifying additives in the form of ultrafine powders on the tribological properties of the developed coatings, is carried out.

The article discusses the effect of epilamated coatings during mandrelling. The picture of the change in contact stresses in the DEFORM-3D system is presented. It was established that a decrease in the coefficient of friction from 0.9 to 0.6 leads to a decrease in the number of foci and areas of contact stresses, as well as temperature analysis showed that a decrease in the friction forces reduces heat transfer in the cutting zone by about 40 ° C.

A simple and affordable method for preparing copper-containing tribological nanomaterials by thermolysis of copper(II) stearate at 300°C was developed. The materials produced were studied by X-ray diffraction, atomic force microscopy, and sedimentation analysis. It was shown that the crystallite size does not depend on the thermolysis time. The tribological properties of lubricants with additives of the produced copper-containing nanomaterials (0.025–0.2%) were studied on an end-face friction test machine. At the optimum concentration of nanomaterials (0.05%), the coefficient of friction is the lowest.

This article presents experimental results for analysis of possibility to replace SCh24 cast iron with aluminum-based composite material produced by internal oxidation. The thermophysical properties of the materials, coefficient of friction, and wear intensity of the considered materials, as well as the temperature dynamics during braking, have been determined.

The aim of the research presented in this article was to determine the value of the friction coefficient using a simple tribological test and to build an empirical model of friction with the use of radial basis function artifi-cial neural networks. The friction tests were carried out on a specially designed friction simulator that allows a sheet metal strip to be drawn between two fixed dies. The test materials were sheets of Ti-6Al-4V titanium alloy with a thickness of 0.5 mm. The friction tests were carried out with variable contact forces of counter-samples with rounded surfaces and in various lubrication conditions. Mineral oils and bio-degradable oils with the addition of boric acid (5 wt %) were tested. Based on the results of friction investigations, neural models of friction were built using RBF artificial neural networks. The good properties of the RBF network 2:2-35-1:1 were confirmed by a high value of the determination coefficient R2 = 0.9984 and a low value of the S.D. ratio equal to 0.0557. It was found that the COF value was the highest for the average values of both the nominal pressure and kinematic viscosity. Over the entire range of nominal pressures applied, SAE10W-40 engine oil ensured the most effective reduction of the COF. The COF value was the highest for the average values of both the nominal pressure and kinematic viscosity.

The discovery of unique properties of the hyaluronic acid and learning about the role of this aid in pathophysiology of extracellular matrices resulted in using this substance in pharmacological support in cases of tissue dysfunction due to numerous disease units. Therefore, the products containing this substance are now widely used in medicine including dermatology and aesthetic medicine, ophthalmology, facial-mandibular surgery and orthopedics, being among the most effective products used in the treatment of numerous cases of function impairment and deformation of tissues and organs. There are applied in both post-traumatic and post-inflammatory conditions as well as in symptoms due to chronic conditions. Their therapeutic effects result from joint surface moisturizing, reduction of the coefficient of friction (COF) and good bio-tolerance and biocompatibility confirmed by a low percentage of side effects and biocompatibility. The introduction of hyaluronic acid hybrid complexes with high and low molecular mass (H/L-HA) has increased the clinical usefulness of hyaluronic acid products thanks to their increased viscoelasticity, increased anti-inflammatory and chondroprotective properties and thermodynamic stabilization of the product guaranteeing its half-life. Thanks to the above mentioned pro­perties it becomes more effective in the non-surgical treatment of osteoarthritis.

In this study, the effects of methyl jasmonate [MeJA (0.5 and 1.0 mmol L-1)] and modified atmosphere packaging (MAP) applications on the physical and mechanical properties of ‘Precoce de Thyrinthe’ apricot variety during cold storage were investigated. Fruit were stored at 0±0.5C and 90±5% relative humidity for 20 days. Physical properties of apricot such as geometric mean diameter, sphericity, surface area, bulk and fruit densities; mechanical properties such as puncture-compression forces and friction coefficient were determined. It was observed that MeJA application did not produce a significant difference on the size characteristics of apricot compared to the harvest period. Regarding the storage time, decreases were observed in the change of compression force results obtained from the X-, Y- and Z- axes according to the increase in the storage time. Effect on the puncture force on three axes showed a lower tendency to decrease in MAP application than in the harvest period compared to the application without MAP. The coefficient of friction on laminate and galvanized sheet surfaces was lower than PVC, plywood and rubber surfaces.

The circular economy is still a hypothetical field in Europe. Different shredding and manufacturing machinery parts in textile industries are presumed to enhance product quality and performance. The quality and performance of recycled textile products play a vital role in the development of textile recycling technologies. The quality is principally associated with the mechanical and tribological properties of machinery parts. In this article, TiCN Coating is used to determine the coefficient of friction of post-consumer cotton fabric. The scanning electron microscope, optical and mechanical profilometer, and tribometer were used for surface and tribological evaluations. The TiCN coating was found smooth and homogeneous. The average coating surface roughness parameters Rmax, Rz, Rp were 0.24 µm, 0.21 µm, and 0.20 µm, respectively. The dynamic coefficient of friction values was found 0.38 to 0.30 in the warp and 0.33 to 0.28 in weft directions. The increase in sliding distance is used for industrial applications and evaluations. The increase in distance deformed and fractured cotton fabric surface. The coefficient of friction and deformation becomes constant after 40 m of sliding distance. Based on coefficient of friction values, permanent deformation, fracture, and morphologies evaluations TiCN coatings could be used operationally for surface modification of textile machinery parts. The surface modification of textile machinery parts with TiCN coating can enhance the quality and performance of textile products.