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Understanding how nanoparticles deform under compression not only is of scientific importance but also has practical significance in various applications such as tribology, nanoparticle-based probes, and the dry grinding of raw materials. In this study, we conducted compression tests on model brittle glassy nanoparticles using molecular dynamics simulations. We found that during the early stages of plastic deformation, shear bands formed in a similar pattern regardless of the nanoparticle size. However, as the deformation continued, dominant cracks emerged in large nanoparticles while being suppressed in smaller ones. This size-dependent brittle-to-ductile transition can be explained by a simple model based on Griffith's theory. We also investigated the effect of the surface stress state on fracture using thermally tempered nanoparticles. We observed that the presence of compressive surface stress strengthened the nanoparticle by suppressing crack formation, even when a pre-notch was present. On the other hand, tensile surface stress had the opposite effect. Interestingly, nanoparticles with both tensile and compressive surface stress promoted shear deformation, which could potentially compromise the mechanical performance of tempered glass despite delayed crack formation. [ABSTRACT FROM AUTHOR]

Ceramic particle reinforced medium entropy alloys (MEAs) coatings have attracted considerable attention because of their excellent hardness and wear resistance. In this study, (CoCrNi) 94 Al 3 Ti 3 MEA coating and (CoCrNi) 94 Al 3 Ti 3 -cBN MEA composite coating were prepared by high-speed laser cladding. The phase constituents, microstructure，hardness and wear mechanisms of the two coatings were investigated using XRD, Raman spectra, SEM, EDS, and TEM. Results show that (CoCrNi) 94 Al 3 Ti 3 comprises only simple FCC phase because of the high-entropy effect. However, the addition of cBN transforms the phase from FCC to FCC + BCC, but also generates micron-scale TiN and CoCr, as well as nanoscale TiN and CrB. In addition, part of the cBN is converted to hBN with lubricating effect under high energy laser. As for the properties, compared with (CoCrNi) 94 Al 3 Ti 3 coating, (CoCrNi) 94 Al 3 Ti 3 -cBN coating exhibits increased hardness by 2.2 times, increased wear resistance by 5.6 times, and decreased friction coefficient from 0.58 to 0.47. It is expected that this research will provide research ideas for the preparation coating of friction reduction and wear resistance performances on titanium alloy surfaces. [ABSTRACT FROM AUTHOR]

The tribological performance of C/C–SiC paired semi-metallic brake pads suitable for automobiles was investigated in this study. Factors on tribological properties of semi-metallic brake pads such as the contents of phenolic resin, copper fibers, steel fibers and MoS 2 were tested by the orthogonal experimental. According to the SAE-J2522 test procedure, an optimized compositional formulation was derived based on the brake test results combined with fuzzy comprehensive evaluation. The wear mechanism of brake pairs was discussed, and the compositional formulation of the brake pad was further optimized after the analysis of the friction surface morphology before and after braking. The results showed that copper fibers had the greatest effect on the friction performance of brake pads. Copper fibers contributed to stabilization of the coefficient of friction (COF) and effectively improved the wear resistance. However, at higher braking speeds (≥120 km/h), the copper fibers were converted from fibrous to flaky and softened, acting as a solid lubricant on the friction surface, resulting in a low COF of brake pads. The tribological performance of brake pads could be improved by reducing the content of copper fiber and increasing the content of hard particles. [ABSTRACT FROM AUTHOR]

Mineral oil–based lubricants play an important role to serve industrial lubrication and cooling requirements. However, these oils are environmentally unacceptable due to their negative impact on human health and environmental ecology. The current research focuses on generating an eco-friendly oil which has enhanced lubrication properties. In this work, a four-ball tribometer was employed for friction and wear evaluation of a palm oil-commercial grade oil (PO-CGO) blend, which consisted of various weight fractions of functionalized multiwall carbon nanotubes (FMWCNTs) to lubricate steel-steel contacts of ball specimens mounted in tribometer. The specimens were lubricated by using 0.1 wt.% FMWCNT blended PO-CGO oil showed about 38% and 35% reduction in wear scar diameter and wear volume respectively compared to CGO lubricated test samples. Furthermore, roughness values of specimens obtained from atomic focal microscope (AFM) by using 0.1 wt.% nanomaterial blended lubricant showed about 88% lower values than that of CGO lubricated specimens. Raman spectroscopy and SEM/EDS results revealed the details of tribofilm formation and corresponding chemical composition on sliding contact surfaces of ball specimens subjected to PO-CGO and FMWCNT-blended oil lubrication. [ABSTRACT FROM AUTHOR]

This article presents the results of pilot studies on the lubrication of the blankholder zone in sheet metal forming using a pressurised lubricant. The authors invented a method and built a special tribometer for pressure-assisted lubrication. This approach reduces friction in sheet metal forming processes compared to conventional lubrication. Moreover, the artificial neural network approach combined with a force-directed Fruchterman-Reingold graph algorithm and Spearman's correlation was used for the first time to analyse the relationships between the friction process parameters and the output parameters (the coefficient of friction and the resulting surface roughness of the sheet metal). The experimental tests were conducted utilising strip drawing on four grades of steel sheets known to be outstanding for deep-drawing quality. Different oils, oil pressures and contact pressures were used. Artificial neural network models were used for the first time to determine these relationships in a strip drawing test where every parameter is represented by one node, and all nodes are connected by edges with each other. R Software version 4.2.3 was used to construct the network using the 'qgraph' and 'networktools' packages. It was found that friction conditions had a highly significant negative correlation with coefficient of friction (COF) and a moderately significant negative correlation with the final surface roughness. However, the initial surface roughness of the as-received sheets had a negative correlation with the COF and a positive one with the resulting surface roughness of the sheet metal. The parameters most related to the COF are the strength coefficient, the ultimate tensile strength and the friction conditions (dry friction or pressurised lubrication). Spearman's correlation coefficients showed a strong correlation between the kinematic viscosity and the friction conditions. [ABSTRACT FROM AUTHOR]

The current investigation delved into the friction and wear characteristics of abrasive-finished Inconel 718 alloys fabricated by additive manufacturing and casting methods. Silicon carbide balls were used as counter-body materials for all tribology tests. Variable loads of 10 N, 20 N, and 30 N were applied, along with frequencies of 5 Hz and 15 Hz, while maintaining a 1 mm stroke length for 30 min. Cast samples showed an increase in coefficient of friction (COF) when the load increased from 10 to 20 N at 5 Hz. COF value was decreased from 0.28 to 0.25 when the load was increased from 20 to 30 N while the frequency was maintained at 5 Hz. At the same frequency of 5 Hz, additively manufactured samples displayed a constant increase in COF from 0.19 to 0.35 as the load increased from 10 to 30 N. Consistent COF values were determined at 15 Hz for cast and additively manufactured samples. The COF for cast samples at a frequency of 15 Hz was 0.26, 0.25, and 0.25 for loads of 10 N, 20 N, and 30 N, respectively. For the same loads and frequencies, COF values of 0.23, 0.24, and 0.24 were reported in additively manufactured samples. At 15 Hz, both cast (7.25 × 10–6 mm3/N.m to 9.91 × 10–6 mm3/N.m) and additively manufactured (5.80 × 10–6 mm3/N.m to 6.18 × 10–6 mm3/N.m) samples exhibited constant increasing trends of specific wear rates when the loads increased from 10 to 30 N. [ABSTRACT FROM AUTHOR]

In recent years, bio-lubricants have received a growing interest for industrial applications. Still, a full-scale implementation in machinery lubrication requires a thorough evaluation of their performance through tribological and operational tests to stand upon their performance. Additionally, the promising outcomes achieved by nanoadditives in improving the performance of synthetic lubricants have prompted research efforts to identify suitable nanoadditives for bio-grease. This paper introduces a bio-grease from a hybrid vegetable oil and glycerol monostearate as a thickener for the lubrication of rolling bearings. Activated carbon nanoparticles (ACNPs) as nanoadditives were synthesized, characterized, and incorporated into the bio-grease at concentrations of 0.5, 1, and 2% by weight. Tribo-tests were conducted on these bio-grease blends, and running tests were carried out using 6006 ball bearings on a custom test rig. Throughout a 30-min test run under a radial load of 10% of the bearing's dynamic load rating, mechanical vibrations and power consumption were measured and analyzed for each bearing. The bio-grease with ACNPs exhibited a substantial reduction in wear scar diameter (WSD) and coefficient of friction (COF), achieving improvements of up to 73.6 and 65%, respectively, in comparison to lithium grease. Furthermore, the load carrying capacity was enhanced by 200%. The study revealed a strong correlation between measured vibration amplitudes and the viscosity of the bio-grease. The absence of high frequency resonant bands in vibration spectra indicated that the test grease samples satisfied the conditions of elastohydrodynamic lubrication, and these findings were corroborated through calculations of the minimum oil film thickness. [ABSTRACT FROM AUTHOR]

The present study aimed to improve and assess the electrical discharge coating (EDC) factors with aluminium 7075 alloy as a substrate. The results of input variables like current, composition, and compaction load on EDC responses, including material deposition rate (MDR), tool wear rate (TWR), and surface roughness (Ra) were studied. Taguchi's L9 experiment design was employed with GRA (grey relational analysis), ARAS (Additive Ratio Assessment), and preference value (Ki) was measured. The experiments determined the best parametric setting for more MDR, less TWR, and less Ra. The level of contribution of the process parameters to the response was evaluated by a statistical test known as ANOVA, wherein current appeared as the most noteworthy parameter, followed by composition and compaction load. The results of GRA and ARAS were compared with a prominent MCDM method known as TOPSIS, which substantiated the outcomes of both methods. Successfully attained rates for material deposition, tool wear, and average surface roughness were 0.385 mg/min for material, 4.37 mg/min for tool wear, and 2.101 µm for surface roughness. Finally, a sensitivity study is used to validate the hybrid model's constancy with a strong correlation. The topography of the deposited surface was analyzed by SEM, wherein base material, deposition, and interface were distinctly visible with the occurrence of a few micro-cracks. The XRD contour of the coating exhibited peaks of Al, Al2Cu, Cu, and SiC. Additionally, the pin-on-disc wear result yielded a substantial drop in the wear of the coated samples as compared to the substrate material. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the performance of bio-based lubricants (BBL), namely, palm mid-olein (PMO) enriched with an antioxidant agent, tertiary-butylhydroquinone (TBHQ) and a viscosity improver, ethylene-vinyl acetate (EVA), in journal bearing (JB) applications. Design/methodology/approach: Samples of the BBL were prepared by blending it with TBHQ and EVA at various blending ratios. The oxidative stability (OS) and viscosity of the BBL samples were examined using differential scanning calorimetry and a viscometer, respectively. Meanwhile, their performance in JB applications was evaluated through the use of a JB test rig with a 0.5 length-to-diameter ratio at various operating conditions. Findings: It was found that the combination of PMO + TBHQ + EVA demonstrated a superior oil film pressure and load-carrying capacity, resulting in a reduced friction coefficient and a smaller attitude angle compared to the use of only PMO or VG68. However, it was observed that the addition of TBHQ and EVA to the PMO did not have a significant impact on the minimum oil film thickness. Practical implications: The results would be quite useful for researchers generally and designers of bearings in particular. Originality/value: This study used PMO as the base stock, and its compatibility with TBHQ and EVA was investigated in terms of its OS and viscosity. The performance of this treated BBL was evaluated in a hydrodynamic JB. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2023-0363/ [ABSTRACT FROM AUTHOR]

[Display omitted] Over the years, reducing friction and wear-induced deformation, damage and/or removal of material at various contact interfaces has always aroused significant interests due to the substantial benefits for impaired machinery components, as well as the efficiencies in energy and economy. Among numerous advanced nanomaterials, carbon nanotubes (CNTs) have been recognized as solid lubricants, or additives in the liquid/solid material systems (coatings, composites and lubricants) to effectively reduce friction and wear. This is well-motivated by CNTs' hollow tubular nanostructure and outstanding physicochemical properties which can potentially support them with many favorable frictional mechanisms, such as filling/mending effect, sliding/rolling effect, and tribofilm-forming effect. Despite the enormous efforts pertaining to CNTs for tribological optimizations, discussing them across the nano-scale to macro-scale for the understanding of critical interactions between the CNTs and contact objects remains rarely explored. In this review, the state-of-the-art advances in computational tribology research of the CNTs and their significant nano/macro-tribology mechanisms in related systems are methodically provided, beginning with a brief overview of CNTs on their manufacturing, structural properties, and functionalization. Additionally, we present a condensed summary of the encouraging findings, accompanied by some valuable recommendations for the sustaining prosperity of CNTs in tribology. [ABSTRACT FROM AUTHOR]

Recently, aiming for the enhanced dispersibility of graphene-based nanomaterials in lubricating oil matrices to serve as highly efficient lubricant additives, numerous modification approaches have been extensively studied. However, these previous modification routes usually involve a tedious multistep modification process or multitudinous toxic reagents, restricting their extensive practical application. In this work, novel graphene oxide (GO) nanoadditives (RGO-g-BO) featuring excellent durable dispersion capability and remarkable tribological performance were successfully prepared via an environmentally friendly one-step approach consisting of surface grafting of long-chain bromooctadecane (BO) and in situ chemical reduction. Benefiting from the greatly improved lipophilicity (resulting from the introduction of hydrophobic long-chain alkane groups and chemical reduction), along with the miniaturization effect, RGO-g-BO exhibits superior long-term dispersion stability in the finished oil. Moreover, the tribological properties results demonstrated that the finished oil filled with RGO-g-BO nanolubricants achieved an outstanding friction-reducing and antiwear performance. Particularly, under the optimum content of RGO-g-BO (as low as 0.005 wt%), the friction coefficient as well as the wear volume of the composite finished oil were greatly reduced by 13% and 53%, respectively, as compared with nascent finished oil. Therefore, in view of the advantages of low-cost, one-step facile synthesis, desirable dispersion capability, and remarkable tribological performance, RGO-g-BO holds great prospects as a highly efficient lubrication additive in the tribology field. [ABSTRACT FROM AUTHOR]

As an excellent solid lubrication material, the poor high-temperature tribological properties of diamond-like carbon (DLC) films severely limit their applications. In this study, tungsten (W) was incorporated into Si-doped DLC films fabricated via reactive magnetron sputtering. The effect of the W content ranging from 0 to 13.12 at.% on the film structure, bonding states, mechanical and high-temperature tribological properties of Si and W co-doped DLC (Si–W-DLC) films has been investigated. The results show that a small amount of tungsten incorporation (4.45 at.%, Si– W L -DLC) increases the mechanical properties of the Si– W L -DLC film without a significant decrease in the fraction of sp3 content. The incorporation of 4.45 at.% W improves the wear resistance and stabilizes the friction coefficient curves at temperatures up to 4 0 0 ∘ C. The high residual stress caused by the highly distorted C–W bond and the low friction coefficient attributed to the formation of WO3 on the sliding surface should be responsible for the excellent tribological performance of the Si– W L -DLC film. It is believed that the Si and W co-doped DLC film can provide another strategy for expanding the high-temperature application of DLC films. [ABSTRACT FROM AUTHOR]

This study explores the feasibility of tribological self‐lubricating over a wide temperature range by doping Si and Sn solid solution components on the A‐sites of Ti3AlC2 to adapt to the severe circumstances. The specimens were sintered at 1450°C for 120 min under a pressure of 30 MPa in a vacuum environment, and their dry sliding tribological capabilities against Al2O3 at temperatures ranging from ambient temperature to 800°C were investigated using a rotational ball‐on‐disk tribo‐tester. The findings demonstrated a constantly decreased friction coefficient of Ti3Al0.8Si0.2Sn0.2C2 throughout the temperature range and admirable antifriction at higher temperatures where wear rates were 1–2 orders of magnitude lower than those at room temperature, which was superior to earlier reported Ti3AlC2. The predominant friction surface self‐adaptability mechanisms after solid solution treatment were determined to be tribo‐oxidation wear and tribo‐chemical reactions that played a vital role by examining the microstructural evolutions and tribo‐chemical phase composition on friction surfaces at various temperatures. The tribo‐oxidation‐induced generated lubricant film consisting of TiO2, Al2O3, SnO2 mixture oxide phases, and aluminosilicates was responsible for the decreased friction coefficient and wear rate. [ABSTRACT FROM AUTHOR]

To investigate the tribological properties of polycrystalline diamond compact (PDC), different additives including graphene, molybdenum disulfide (MoS 2), and a combination of graphene + MoS 2 were utilized. The microstructure and chemical reactions of PDC were analyzed using techniques such as atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The focus was on the formation and degradation of the friction film. The findings revealed that both graphene + MoS 2 exhibit excellent lubrication properties, forming a protective friction film on the surface of PDC. Furthermore, the combined use of graphene + MoS 2 demonstrated a synergistic effect, resulting in enhanced wear resistance of PDC compared to the individual use of graphene or MoS 2 alone. [ABSTRACT FROM AUTHOR]

Herein, we present the results of an experimental study on the mechanical properties of Fe-C alloys with different carbon contents (0.2, 0.45, and 0.8%) in a wide range of deformation rates (10−3–103 s−1) and abrasive wear resistance, which underwent combined laser thermal (laser surface hardening—LSH) and laser shock wave (Laser Shock Peening—LSP) processing. The combined treatment modes included a different sequence of exposure to laser thermal and laser-induced shock pulses on the material. The amplitude and duration of laser-induced shock waves were measured using a laser Michelson interferometer. The mechanical properties of steel samples were studied under conditions of uniaxial tension under static loads on a standard universal testing machine, the LR5KPlus, and under dynamic loading, tests were carried out on a specialized experimental complex according to the H. Kolsky method using a split Hopkinson rod. The abrasive wear resistance of hardened surfaces was studied using the Brinell–Haworth method. Studies have shown that the use of a combination of LSH and LSP treatments leads to an increase in both the mechanical properties of steels and abrasive wear resistance compared to traditional laser hardening. It has been established that in the combinations considered, the most effective is laser treatment, in which LSP treatment is applied twice: before and after LSH. Thus, after processing steels using this mode, an increase in the depth of the hardened layer was recorded—by 1.53 times for steel 20, by 1.41 times for steel 45, and by 1.29 times for steel U8—as well as a maximum increase in microhardness values by 22% for steel 20, by 27% for steel 45, and by 13% for U8 steel. The use of this mode made it possible to obtain the maximum strength properties of the studied materials under static and dynamic loading, which is associated with an increase in the volume fraction of the strengthened metal and high microhardness values of the strengthened layer of traditional LSH. The dependences of abrasive wear of the studied steels after various combinations of LSP and LSH impacts were established. It is shown that the greatest wear resistance of the studied steels is observed in the case when the LSH pulse is located between two LSP pulses. In this case, abrasive wear resistance increases by 1.5–2 times compared to traditional LSH. [ABSTRACT FROM AUTHOR]

In recent studies concerning walking robots, there has been a notable emphasis on investigating tribological phenomena and elucidating the role of capillary forces in tangential resistance. However, majority of these investigations have been restricted to specific geometric shapes, primarily spherical domes. In this research, we propose a novel approach based on the finite element method to address broader challenge of wet adhesion applicable to objects of various shapes. Additionally, we investigate the role of distributed domes on a soft foot in quantifying the tangential capillary force, which plays a crucial role in enhancing the performance of walking robots on wet surfaces. Through the optimization application, we identify that our designed foot (measuring 20 mm × 14 mm, comprising 78 domes with a radius of 0.5 mm and a distance of 1.5 mm between the two nearest domes) maximizes the value of the tangential capillary force. Moreover, we develop a finite element method using the Simulation Open Framework Architecture (SOFA) to model the interaction between wet liquid on a solid object's curved surface, enabling the calculation of wet adhesion force and capillary forces. Finally, to demonstrate the effectiveness of our proposed morphology-changeable soft pads foot, we conduct a presented a demonstration of a hexapod robot walking on different dry/wet condition of the surface. The obtained results are expected to pave a way to morphological design of soft pads for facilitating locomotion in various conditions. Supplementary video URL: [ABSTRACT FROM AUTHOR]

Friction and wear phenomena are common problems in sliding equipment, so materials with excellent antifriction and wear resistance properties are getting increasingly more attention. Two-dimensional (2D) materials, such as graphene and molybdenum disulfide, have always been the research hotspots on account of their special structures and excellent tribological properties. In 2011, MXene, an important member of the 2D material family, was launched. With excellent properties such as ultra-high strength, rich surface end groups, and relatively low cost, MXenes have great potential as lubricant additives. Although these properties have proved to be the reason why MXenes are impressive, the preparation of MXenes composites and the understanding of their mechanical and tribological mechanisms remain to be further investigated. In addition, the abundant surface end groups of MXenes nanosheets make them relatively easy to be functionalized, which has attracted widespread attention. This review aims to comprehensively understand the tribological properties of MXenes nanolayers and to summarize and sort out recent research progress. First, the preparation of MXenes is reviewed, and then the latest research progress of MXenes in liquid lubrication, solid lubrication, and solid–liquid hybrid systems since the advent of MXenes is summarized. Finally, some current problems are presented and an outlook on the development of MXenes is given. [ABSTRACT FROM AUTHOR]

This reports the tribological behavior of sintered aluminum composite with bio-oil as lubricant. The composite is fabricated by powder metallurgy route, and the aluminum is reinforced with the particles V2O5 and B4C. The bio-lubricant oil is Pongamia, Jatropha, and blended Pongamia with Jatropha of equal volume. The wear test was carried out at the sliding speed of 3m/s and load ranging up to 180 N, and the wear behavior of Al–xV2O5–2B4C composite. Then the composite’s friction coefficient and weight loss were tested on a pin-on-disc tribometer. Further, pinworn surfaces were analyzed by Scanning Electron Microscope. The mix of Pongamia with Jatropha of equal volume resulted in a good change in specific wear rate and coefficient of friction of composites. [ABSTRACT FROM AUTHOR]

Friction, wear, and the consequent energy dissipation pose significant challenges in systems with moving components, spanning various domains, including nanoelectromechanical systems (NEMS/MEMS) and bio-MEMS (microrobots), hip prostheses (biomaterials), offshore wind and hydro turbines, space vehicles, solar mirrors for photovoltaics, triboelectric generators, etc. Nature-inspired bionic surfaces offer valuable examples of effective texturing strategies, encompassing various geometric and topological approaches tailored to mitigate frictional effects and related functionalities in various scenarios. By employing biomimetic surface modifications, for example, roughness tailoring, multifunctionality of the system can be generated to efficiently reduce friction and wear, enhance load-bearing capacity, improve self-adaptiveness in different environments, improve chemical interactions, facilitate biological interactions, etc. However, the full potential of bioinspired texturing remains untapped due to the limited mechanistic understanding of functional aspects in tribological/biotribological settings. The current review extends to surface engineering and provides a comprehensive and critical assessment of bioinspired texturing that exhibits sustainable synergy between tribology and biology. The successful evolving examples from nature for surface/tribological solutions that can efficiently solve complex tribological problems in both dry and lubricated contact situations are comprehensively discussed. The review encompasses four major wear conditions: sliding, solid-particle erosion, machining or cutting, and impact (energy absorbing). Furthermore, it explores how topographies and their design parameters can provide tailored responses (multifunctionality) under specified tribological conditions. Additionally, an interdisciplinary perspective on the future potential of bioinspired materials and structures with enhanced wear resistance is presented. [ABSTRACT FROM AUTHOR]

With the development of the shipbuilding industry, it is necessary to improve tribological properties of polyether ether ketone (PEEK) as a water-lubricated bearing material. In this study, the sulfonated PEEK (SPEEK) with three distinct chemical structures was synthesized through direct sulfonated polymerization, and high fault tolerance and a controllable sulfonation degree ensured the batch stability. The tribological and mechanical properties of SPEEK with varying side groups (methyl and tert-butyl) and rigid segments (biphenyl) were compared after sintering in a vacuum furnace. Compared to the as-made PEEK, as the highly electronegative sulfonic acid group enhanced the hydration lubrication, the friction coefficient and wear rate of SPEEK were significantly reduced by 30% and 50% at least without affecting the mechanical properties. And lower steric hindrance and entanglement between molecular chains were proposed to be partially responsible for the lowest friction behavior of SPEEK with methyl side groups, making it a promising and competitive option for water-lubricated bearings. [ABSTRACT FROM AUTHOR]

For the tribological properties of nanoparticle-modified PTFE, a more comprehensive study has been conducted, but there is still some room for research on tribology behavior, tribofilm formation and structure evolution of polytetrafluoroethylene (PTFE) filled with α-Al2O3 and SiO2 nanoparticles during sliding against steel counterparts under different loads. At the same time, it establishes the linkage and mechanism between the maintenance of mechanical strength and the tribological application of polymers in service and provides corresponding scientific data and theoretical guidance for the long-lasting application of polymer lubrication materials. It is found that both composites exhibit good wear resistance across the pressure of 1 MPa to 10 MPa, with the α-Al2O3/PTFE composite demonstrating better performance stability compared to the SiO2/PTFE composite. The high wear resistance is attributed to the formation of tribofilms at the friction interface. For the α-Al2O3/PTFE, an island-like tribofilm is formed with a thickness ranging from 100 to 200 nm, while the tribofilm of the SiO2/PTFE composite is thinner, measuring approximately 50 to 100 nm, and manifests a striped pattern. The chemical composition, both at the surface and subsurface levels, as well as the morphology of the tribofilms, were studied using FTIR spectrometry, X-ray photoelectron spectroscopy (XPS), and FIB-TEM. It is found that the difference in thickness and microstructure of the tribofilms for the two composites is mainly due to the tribochemistry of the nanoparticles. The α-Al2O3 nanoparticle plays a "cohesion" role during the formation of the tribofilm, which facilitates the formation of a thicker, more uniform, and stronger adhered tribofilm on the metallic counterpart, making it more robust against higher shear stress. [ABSTRACT FROM AUTHOR]

Polyamide 11 (PA11) and copolyester (TPC-E) were compounded through melt extrusion with low levels (below 10%) of expanded graphite (EG), aiming at the manufacturing of a thermally and electrically conductive composite resistant to friction and with acceptable mechanical properties. Thermal characterisation showed that the EG presence had no influence on the onset degradation temperature or melting temperature. While the specific density of the produced composite materials increased linearly with increasing levels of EG, the tensile modulus and flexural modulus showed a significant increase already at the introduction of 1 wt% EG. However, the elongation at break decreased significantly for higher loadings, which is typical for composite materials. We observed the increase in the dielectric and thermal conductivity, and the dissipated power displayed a much larger increase where high frequencies (e.g., 10 GHz) were taken into account. The tribological results showed significant changes at 4 wt% for the PA11 composite and 6 wt% for the TPC-E composite. Morphological analysis of the wear surfaces indicated that the main wear mechanism changed from abrasive wear to adhesive wear, which contributes to the enhanced wear resistance of the developed materials. Overall, we manufactured new composite materials with enhanced dielectric properties and superior wear resistance while maintaining good processability, specifically upon using 4–6 wt% of EG. [ABSTRACT FROM AUTHOR]

Structural superlubricity, one of the most important concepts in modern tribology, has attracted lots of interest in both fundamental research and practical applications. However, the underlying model, known as the Prandtl–Tomlinson (PT) model, is oversimplified and not for real processes, despite its prevalence in frictional and structural lubricant studies. Here, with a realistic system, cholesteric liquid crystals confined between two atomically smooth surfaces, we measure both the surface torque during rotational friction and the molecular rotation from the commensurate to incommensurate configuration at the onset of structural lubricity. Furthermore, by changing the surface potential or the strain, the Aubry transition is confirmed. The results agree well with the description by a quasi-one-dimensional version of the PT model and provide molecular evidence for rupture nucleation during static friction. Our study bridges the gap between theories and experiments and reinforces the connection between friction and fracture. [ABSTRACT FROM AUTHOR]

In this work, the Metal Inert Gas (MIG) welding process is used for depositing the Inconel 718 over the base substrate of Stainless steel 321. The optimal welding conditions like 50% overlap, Direct Current (DC) plus mode with a pulse on time (1–5 s), frequency (0.25–1 Hz), peak current (120 A), base currents (60% of peak current), and speed (150–350 mm/min) are used for the successful hard-facing. The quality of the hard-facing is analyzed by conducting microstructural studies, tensile tests, microhardness, wear behavior, and electrochemical studies. Post-processing for wear and electrochemical studies is done by Scanning Electron Microscope SEM–EDX analysis. Microstructural studies revealed the presence of columnar dendrites and equiaxed at the top of the hard-faced layer. Hard-faced layer depicts the highest ultimate tensile strength of 772 N/mm2 with an elongation of 31.50% due to the support of Nickel components. The presence of the voids and dimples is identified from the SEM fractography. The maximum hardness value of 212 HV 0. 5 is measured at the top of the hard face layer. The microhardness of the hard-faced layer increased by 17.77% higher than its base substrate. Because of the hard precipitates and higher microhardness made by the weld thermal cycle, the hard-face layer showed maximum Co-efficient of Friction (CoF) of 0.540. Debris and grooves are found with the SEM examination of the wear specimens. Higher impedance offers better corrosion resistance to the hard-faced layer Inconel 718. The EDX analysis confirms the presence of Chromium, Molybdenum, and Niobium contents at the hard-faced layer. These elements silently support better corrosion resistance compared to the base substrate of Stainless steel 321. [ABSTRACT FROM AUTHOR]

Nanostructures as an inert additive to the lubricant act as a tiny friction reduction element by providing asperity filling, polishing, and film formation mechanism at the nanoscale dimension under the boundary layer regime. Here, we explore the synthesis and tribology application of iron‐carbon‐based nanoparticles encapsulated multiwall carbon nanotubes (Fe‐C‐CNTs). Three Fe‐C nanoparticles phase that is, Fe3C‐CNTs, Fe3C‐Fe‐CNTs, and Fe‐CNTs are synthesised. In particular, the emphasis here is on the effect of nanoparticle phase variation on the tribology property. The tribology property of the prepared nanomaterials is studied by dispersing it in commercially used Servo gearbox oil. The coefficient of friction and wear is found reduced in all dispersions compared to the base gearbox oil confirming the manifestation of nanoscale mechanisms at the tribo‐interface. It is revealed that the phase variation shows more impact on the alteration of friction coefficient compared to the dispersion concentration variation analysed using ANOVA two‐way technique. Further, the diameter and composition analysis of the wear scar is used to comprehend the underlying mechanism of the encapsulated particle phase variation. The findings suggest that the Fe‐CNTs dispersions are efficient in reducing friction to a larger extent but also promote the interface oxidation leading to enhanced wear and roughness whereas, Fe3C‐CNTs and Fe3C‐Fe‐CNTs are chemically stable providing smooth sliding and less wear. [ABSTRACT FROM AUTHOR]

Three types of polyimide/polyamide imide/epoxy resin (PI/PAI/EP) coating materials filled with different amounts of WS2 and ZnO were designed, and the coatings were prepared on the surface of 1010 steel substrates using liquid spray coating technology. The mechanical and tribological characteristics of these coatings were investigated. The CoFs (coefficients of friction) of these coatings were lower than those of the copper alloy proposed to be replaced under dry sliding wear and water lubrication. The lowest CoF of 0.237 was achieved with 7.35 wt% WS2, and the highest CoF of 0.251 was observed for 4 wt% ZnO. However, the coating with 7.35 wt% WS2 had the lowest hardness and poorest load-bearing capacity under water lubrication. The coating with 4 wt % ZnO had the best load-bearing capacity and the lowest wear rate. The agglomeration of the coating on the substrate was influenced by the content of ZnO. The CoF of the coating was influenced by both the transfer film formed by WS2 and the amount of ZnO floating on the surface of the coating. The embedding of sand into the coating surface during friction increased the surface roughness, which led to an increase in the CoF. [ABSTRACT FROM AUTHOR]

The necessity of increasing the efficiency and reducing the carbon foot-print of machines is pushing centrifugal compressor bearings design to higher and higher peripheral speed and lower oil consumptions especially in the new energy transition fields, resulting in an increase in the bearing temperatures. Therefore, the bearing thermal management starts to play a major role in extending the machine operability and reducing the maintenance frequency. A full three-dimensional (3D) parametric conjugate heat transfer computational fluid dynamic (CFD) model for tilting pad journal bearings (TPJBs) is introduced in this paper to address the temperature aspects of oil-film bearings. The parametric geometry of the model and the automatic mesh update, allow the equilibrium position search to be obtained without adopting any dynamic mesh algorithms. The tilting pad and rotating shaft equilibrium position are automatically calculated with a Newton-Raphson algorithm. The static performance of the TPJB is investigated for different journal diameters, bearing clearance, and operating conditions. The numerical results obtained are compared with experimental data from compressor mechanical running tests to demonstrate the reliability of the model presented. The 3D distributions of the oil pressure, velocity, and temperature given by the CFD model, can be locally optimized to face the new energy transition challenges. [ABSTRACT FROM AUTHOR]

Abradable environmental barrier coatings (EBCs) are used to reduce clearances between blades and casings in the hottest parts of aero gas turbines, increasing the overall efficiency of the turbine, however, research into the mechanical performance of such coatings is limited. The aim of this work was to better understand the relationship between microstructure and erosion and wear performance in abradable EBCs, since publicly available literature regarding such coatings is scarce and the potential efficiency gains in gas turbines are significant. In this study, ytterbium disilicate abradable EBCs containing three different porosity levels (determined by fugitive polyester phase addition) were deposited using atmospheric plasma spraying with porosity levels of 8, 15 and 21.5% by area. These coatings were then characterised in numerous ways; the porosity was quantified, the thermal conductivity was measured, the superficial hardness and erosion resistance were measured, and finally, the coatings were subjected to a rig test designed to simulate in-service cutting mechanisms against a tipped turbine blade. The results show that increasing the level of porosity via increasing the amount of pore forming phase in the feedstock, led to reduced erosion resistance and improved cutting by a turbine blade. [ABSTRACT FROM AUTHOR]

Tribological characteristics of fine-grained dual-phase high-entropy carbide/boride ceramics were investigated using the ball-on-flat dry sliding method in air, applying linear reciprocation motion with SiC counterpart. Detailed fractographical analyses were used for the characterization of the deformation and damage mechanisms. The investigated system with composition (Ti 0.14 Zr 0.2 Nb 0.2 Hf 0.2 Ta 0.26)C + (Ti 0.38 Zr 0.18 Nb 0.22 Hf 0.115 Ta 0.105)B 2 showed density with value 8.72 g/cm3 and very high hardness of HV1 29.4 ± 2.0 GPa. The friction coefficient at the test with 5 N was 0.56 and during the test with 10 N and 25 N loads were 0.48 and 0.5, respectively. The effective wear rates at the loads of 5 N and 25 N were very similar with values of 7.93 × 10−7 mm3/Nm and 6.63 × 10−7 mm3/Nm. At load 50 N the effective wear rate is significantly higher with a value of 9.11 × 10−6 mm3/Nm. Detailed fractography revealed that the dominant wear mechanisms at loads of 5 N and 25 N were an oxidation-driven tribochemical reaction and tribo-layer formation in boride grains and mechanical wear in carbide grains and at the load of 50 N fracture of boride and carbide grains and formation of chemically complex tribolayers. [ABSTRACT FROM AUTHOR]

Digital technologies sustain today's world. Every part of the world is working towards digital technologies, which none of us can eliminate. Enormous growth is achieved only by unexpected acceleration by digital technologies, including the Internet of Everything (IoE), Artificial Neural Networks (ANN), Machine Learning (ML), Internet of Things (IoT), Artificial Intelligence (AI), Deep Learning (DL), and many more. These technologies started occupying all the engineering sectors, including manufacturing. This paper focuses on tribology analysis related to manufacturing concerning various digital manufacturing technologies. The paper narration includes Tribology using digital technologies wherein the journals and patent landscape analysis abet them. In trend, Tribology utilizes all these technologies today and envisages its growth with the predominant technological invention in the border view. The survey of various literature reveals that only three digital technologies, including AI, ML, and ANN, are used by tribologists around the globe. Other Technologies like Evolutionary Algorithm (EA), Support Vector Machine (SVM), and Adaptive Neuro-Fuzzy Interference Systems (ANFIS) are not used predominantly. [ABSTRACT FROM AUTHOR]

Highlights A hybrid of halloysite nanotubes decorated with titanium dioxide nanoparticles (HNTs@TiO2) was synthesized by the sol–gel method and then mixed with ultra‐high molecular polyethylene (UHMWPE) by melt compounding to enhance its wear resistance properties. The incorporation of HNTs@TiO2 increased the crystallinity as well as the hardness of UHMWPE nanocomposites, which benefited less prone to plastic deformation during the friction process. In addition, the UHMWPE/HNTs@TiO2 maintained a high ductility character with a slight decrease in tensile strength compared to pure UHMWPE. With the addition of 3 wt% HNTs@TiO2, the UHMWPE nanocomposite achieved a remarkably low friction coefficient of 0.073 and a reduced wear rate of 6.67 × 10−6 mm3/N·m. These values represented a 32.4% decrease in friction coefficient and a 43.9% decrease in wear rate compared to pure UHMWPE. The improvement in wear resistance was due to the dislodged TiO2 and HNTs had good synergistic rolling effects at the counterface. Furthermore, the wear scan morphology observation revealed that the transferred HNTs@TiO2‐based materials could help to improve the quality of the tribofilms, which alleviated the abrasive wear from the metallic counterpart. This work offers a feasible way to enhance the wear resistance of UHMWPE nanocomposite without sacrificing the high ductility for expanding its engineering applications. TiO2‐decorated halloysite nanotubes were synthesized by the sol–gel method. The addition of HNTs@TiO2 maintained the high ductility character of UHMWPE. The UHMWPE composite with 3 wt% HNTs@TiO2 had the best wear resistance. [ABSTRACT FROM AUTHOR]

This paper presents the results of research on the microstructure, mechanical, and tribological properties of Cu/0.5 wt.% MWCNT (multi-walled carbon nanotube) sintered composite materials produced by powder metallurgy. The purpose of this research was to investigate the impact of carbon nanotube modifications on the uniformity of their dispersion and the effectiveness of their bonding with the matrix. The MWCNTs were modified by chemical oxidation. Additionally, a modification of the ingredient mixing method utilizing ultrasonic frequencies was employed. The tests were carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers hardness tests, static compression tests, and wear tests using the pin-on-disc method. Furthermore, mechanical properties and strain distribution analyses of the micro-specimens were conducted using the Micro-Fatigue System (MFS). The implemented modifications had a positive effect on the dispersion of MWCNTs in the copper matrix and on the mechanical and tribological properties of the sinters. [ABSTRACT FROM AUTHOR]

The growing demand for modern steels showing corrosion and tribological resistance has led to their increased use in the production of medical devices. This study analyzed the effect of shot peening on wear resistance in 0.9% NaCl solution of 17-4PH steel produced by direct laser metal sintering (DMLS) technology. The study's novelty relies on revealing the effect of shot peening (SP) surface treatment on the wet sliding wear resistance of 17-4PH steel produced with DMLS. Moreover, in the context of 17-4PH steel application for medical devices, the 0.9% NaCl tribological environment were selected, and SP processes were conducted using steel CrNi shot and ceramic (ZrO2) beads. The up-to-date scientific literature has not identified these gaps in the research. DMLS technology makes it possible to obtain products with complex architectures, but it also faces various challenges, including imperfections in the surface layer of products due to the use of 3D printing technology itself. The chemical and phase composition of the materials obtained, Vickers hardness, surface roughness, and microscopic and SEM imaging were investigated. Tribological tests were carried out using the ball-on-disc method, and the surfaces that showed traces of abrasion to identify wear mechanisms were subjected to SEM analysis. The XRD phase analysis indicates that austenite and martensite were found in the post-production state, while a higher martensitic phase content was found in peened samples due to phase transformations. The surface hardness of the peened samples increased by more than double, and the post-treatment roughness increased by 12.8% after peening CrNi steels and decreased by 7.8% after peening ZrO2 relative to the reference surfaces. Roughness has an identifiable effect on sliding wear resistance. Higher roughness promotes material loss. After the SP process, the coefficient of friction increased by 15.5% and 20.7%, while the wear factor (K) decreased by 25.9% and 32.7% for the samples peened with CrNi steels and ZrO2, respectively. Abrasive and adhesive mechanisms were dominant, featured with slight fatigue. The investigation showed a positive effect of SP on the tribological properties of DMSL 17-4PH. [ABSTRACT FROM AUTHOR]

The complex dynamics of tribofilm formation on boundary-lubricated steel surfaces were investigated in real time by combining in situ measurements of the temporal variation of the coefficient of friction and contact voltage. Sliding experiments were performed with various blends consisting of base oil, zinc dialkyl dithiophosphate (ZDDP) additive, and two different dispersants at an elevated oil temperature for a wide range of normal load and fixed sliding speed. The evolution of the transient and steady-state coefficient of friction, contact voltage, and critical sliding distance (time) for stable tribofilm formation were used to evaluate the tribological performance of the tribofilms. The blend composition affected the load dependence of the critical sliding distance for stable tribofilm formation. Tribofilm friction was influenced by competing effects between the additive and the dispersants. Among various formulations examined, the tribofilm with the best friction characteristics was found to be the blend consisting of base oil, a small amount of ZDDP, and a bis-succinimide dispersant treated with ethylene carbonate. The results of this study demonstrate the effectiveness of the present experimental approach to track the formation and removal of protective tribofilms under boundary lubrication conditions in real time. [ABSTRACT FROM AUTHOR]

In this work, epoxy composites filled with flake graphite of various size (less than 10 μm and less than 45 μm) were produced. The aim of the research was to develop a self-lubricating material with favorable tribological properties, i.e., reduced friction coefficient compared to unfilled epoxy resin and limited abrasive wear. The research material was produced using technical epoxy resins based on bisphenol A. The detailed process of composite production was described, and typical technological problems were considered. The addition of graphite led to an increase in dynamic viscosity, which positively limits the phenomenon of sedimentation, but an increase in the filler content also led to an increase in the porosity of the material. A series of tests have shown that the addition of graphite above 5% by weight allows for a reduction in the friction coefficient from 0.6 to 0.4 and significantly reduces the material's tendency to abrasive wear. [ABSTRACT FROM AUTHOR]

For 20 years now, the French machining activities have been federated around the Manufacturing'21 group. The activities of this group cover all the issues related to mechanical manufacturing of machines, robots, tool path, and analysis of the cutting process.. This review article is interested in this last part: the analysis of the cutting process. The article tries to make a review of the machining activities made during the past years by focusing on several points. The first one is the behaviour of materials by addressing the cutting process in the primary zone, the tribology in machining and the surface integrity. Secondly, this article reviews the work on tool wear analysis. This section begins with the work that explains wear phenomena. This is followed by work on tool wear, and finally by models. This article ends with a part in which the cutting assistance is discussed where the laser assistance, the high pressure and the cryogenic assistance are exposed. [ABSTRACT FROM AUTHOR]

The objective of the research is to analyze the impact of the ultrasonic vibration assistance on the wear resistance due to the topography enhancement caused on Ti6Al4V cylindrical samples after surface modification through a ball burnishing process. The process parameters considered for this study are the burnishing force, the number of passes, and the addition of a 40 kHz ultrasonic assistance, which are thought to enhance the surface topography and increase the hardener effect in terms of depth. A complete screening design of 3 factors was performed, revealing that the number of passes and the vibration assistance are the most important parameters for minimizing the wear volume loss, being 170 N of burnishing force, 3 passes, and the addition of the vibration assistance as the best combination found. However, no significant difference in the friction force was observed. The topography results show that there is a decrease in the average roughness from 1.50 to 0.45 μm with optimal burnishing conditions. It was also analyzed the microstructure originated after the turning, the conventional ball burnishing, and the vibration-assisted ball burnishing, being the last optimal in terms of depth affectation to the microstructure. Therefore, these results confirm an improvement in terms of wear enhancement, friction reduction, and topography results when vibration assistance is added to a conventional ball burnishing process. [ABSTRACT FROM AUTHOR]

Friction and wear are two critical tribological factors that instigate unavoidable failures of moving components in the mechanical system. Additionally, these factors have a huge impact on global energy consumption, economy, and CO 2 emissions. Minimization of friction and wear in mechanical systems is rather challenging, however, significant advancement has been achieved in the development of new techniques to mitigate these tribological issues. Surface coating is one of the most commonly used techniques to reduce/eliminate tribological failures. Though a wide range of hard and anti-wear coating materials (metallic alloys, carbon, metallic glasses, polymers, ceramics, and composites) have been developed in the last few decades, however, ceramic coatings have always been a prime interest to researchers owing to their outstanding hardness, wear resistance, corrosion resistance, and damping capacity. Specifically, nitride ceramic coatings have been passed a long journey as hard and wear-resistance protective coatings in multiple industries such as manufacturing, automobile, aerospace, etc. This article reviews the journey of the development of nitride coatings for tribological applications. These developments include first-, second-, and third-generation nitride ceramic coatings, which include binary, ternary, multi-elemental as well as multi-layered coating compositions. This review paper sheds light on the available literature, merits, demerits, and applications of all nitride ceramics coatings for tribological applications. Recently, an innovation in nitride ceramic coatings has been reported, which is the utilization of the high entropy concept in these coatings, which has been reported to improve their tribological properties tremendously. This review paper also delivers a comprehensive review of high-entropy nitride ceramic coatings (both equimolar and non-equimolar compositions) for tribological applications, which is the latest and hot topic for researchers working on ceramics coatings and tribology. At last, this review paper identifies the gaps and provides the future possibilities of research in this area. [ABSTRACT FROM AUTHOR]

Society of automotive engineers (SAE) 52100 (100Cr6) steel, used in manufacturing bearings and shafts, deserves attention due to wear and corrosion problems that cause machine losses in the industry. To solve these problems, heat treatments such as quenching and tempering are adopted to reduce wear mechanisms. However, in this work, the effect of these previous heat treatments on the final properties of plasma nitrided steel at three different temperatures (400, 450, and 500 °C) is evaluated. Surface hardness, tribological behavior, and corrosion resistance are evaluated. In the results of Vickers hardness, wear, and electrochemical analysis, it is shown that performing plasma nitriding at 400 and 450 °C on previously heat‐treated SAE 52100 steel provides better mechanical resistance and chemical integrity in a corrosive environment, making the studied steel more comprehensive for important industrial applications. [ABSTRACT FROM AUTHOR]

Cold spray (CS) technology has proven a great potential in the production of composite coatings, enabling the production of materials with superior qualities such as enhanced tribological behavior. This study aims to investigate the tribological properties of CS Al-based composite coatings reinforced by quasicrystalline (QC) particles. Two different Al alloys were used as the matrix, AA 6061 and AA 2024, and mixed with Al-based QC particles (Al-Cr-Fe-Cu) at different Al/QC ratios. A room-temperature ball-on-disc test was then used to evaluate the wear resistance of the composite CS coatings in air and compared to those of the non-reinforced Al alloy CS coatings as well as a cast counterpart (AA 6061-T6). We have demonstrated that CS could be employed to produce thick and dense Al-QC composites that can retain up to about 50 wt.% QC reinforcement in the structure. The incorporation of the QC particles increased the wear resistance by a factor of 7. [ABSTRACT FROM AUTHOR]

A previous study on the pull-off testing of metallized carbon fiber-reinforced polymers (CFRPs) via cold spray showed that better adhesion strengths could be obtained when features such as carbon fibers or surfacing elements were present, by providing potential mechanical interlocking features. In this work, a first approach to determining the effect of the fiber orientation on the deposition and bonding of the metallic coating to the thermoplastic composite substrate is explored. Pure Sn powder was cold sprayed onto two thermoplastic Polyether–Ether–Ketone (PEEK) CFRP substrates, containing carbon fibers with different orientations: one had fibers in the plane of the substrate (unidirectional tape), while the other had fibers mostly perpendicular to the substrate (ZRT film). Characterization of the coatings was performed via scanning electron microscopy (SEM) and confocal microscopy, and some aspects of mechanical testing (namely wear and scratch testing) were carried out to assess the effect of the substrate on the properties of the coatings. A slight improvement of the coating deposition was observed on the sample with the ZRT film, and this was associated with deeper penetration of tin into the substrate, around the carbon fibers, for improved mechanical interlocking. Wear testing did not seem to reveal any differences between both samples. Finally, scratch adhesion tests were performed to qualitatively assess the bonding mechanism at the coating-substrate interface, and while adhesive failure seems to be the main failure mechanism, the coating of the Z sample seems to co-deform with the substrate during testing, which could highlight better adhesion strength. [ABSTRACT FROM AUTHOR]

This study investigated the potential of inedible mustard oil (MO) (Brassica juncea) as a suitable bio-lubricant for enhanced thermal, oxidative stability, and tribological performance. To improve the MO's oxidative stability, it was subjected to a chemical epoxidation reaction, forming epoxidized mustard oil (EMO). The MO and EMO were evaluated for viscosity, functional groups, wettability, oxidative stability, thermal stability, friction, and wear performance. The epoxidation process resulted in nearly doubling the oxidative stability, as well as improving the thermal stability of the MO. Results showed that the EMO exhibited better lubricating properties than the MO, including lower friction and wear. To further improve the lubrication performance of the EMO, solid lubricant additives (SLAs) were incorporated in various concentrations. These SLAs were graphene nanoplatelets (GNP) and hexagonal boron nitride (hBN). The GNP and hBN nano lubricants reduced friction by 31% and 13% compared to the EMO. The same nano lubricants also lowered wear by 73% and 51% relative to the EMO. The underlying mechanisms behind the improvement in the friction and wear performance were discussed. The EMO can be considered as a suitable base stock for renewable and sustainable energy applications. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to study the synergistic lubrication effects of Sn–Ag–Cu and MXene–Ti3C2 to improve the tribological properties of M50 bearing steel with microporous channels. Design/methodology/approach: M50 matrix self-lubricating composites (MMSC) were designed and prepared by filling Sn–Ag–Cu and MXene–Ti3C2 in the microporous channels of M50 bearing steel. The tribology performance testing of as-prepared samples was executed with a multifunction tribometer. The optimum hole size and lubricant content, as well as self-lubricating mechanism of MMSC, were studied. Findings: The tribological properties of MMSC are strongly dependent on the synergistic lubrication effect of MXene–Ti3C2 and Sn–Ag–Cu. When the hole size of microchannel is 1 mm and the content of MXene–Ti3C2 in mixed lubricant is 4 wt.%, MMSC shows the lowest friction coefficient and wear rate. The Sn–Ag–Cu and MXene–Ti3C2 are extruded from the microporous channels and spread to the friction interface, and a relatively complete lubricating film is formed at the friction interface. Meanwhile, the synergistic lubrication of Sn–Ag–Cu and MXene–Ti3C2 can improve the stability of the lubricating film, thus the excellent tribological property of MMSC is obtained. Originality/value: The results help in deep understanding of the synergistic lubrication effects of Sn–Ag–Cu and MXene–Ti3C2 on the tribological properties of M50 bearing steel. This work also provides a useful reference for the tribological design of mechanical components by combining surface texture with solid lubrication. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0381/ [ABSTRACT FROM AUTHOR]

Molybdenum disulfide is an effective solid lubricant, but it suffers from oxidation and moisture absorption issues, resulting in insufficient wear resistance and a shortened lifespan. This study introduces an innovative approach, integrating graphitic carbon nitride with molybdenum disulfide via advanced microwave‐assisted synthesis, offering precise control over synthesis parameters. The research assesses the tribological performance, comparing it with conventional hydrothermal synthesis. The study extensively investigates the morphology, microstructure, and tribology of a g‐C3N4/MoS2 nanocomposite created through novel microwave (g‐C3N4/MoS2‐MW) and hydrothermal techniques (g‐C3N4/MoS2‐HT). MoS2 exhibits a flower‐like structure, while graphitic carbon nitride has a layered structure, as confirmed by elemental analysis via energy‐dispersive X‐ray spectroscopy. X‐ray diffraction identifies g‐C3N4 peaks at 13.0° (100) and 27.5° (002) and hexagonal MoS2 peaks at 14° (002), 32.7° (100), 35.8° (102), and 58.3° (110). The Fourier‐transform infrared spectrum reveals peaks at 1237.4 and 808 cm−1 (aromatic and triazine ring breathing modes in g‐C3N4), 1407.1 and 1638.9 cm−1 (C=N and C−C heterocyclic structures), and 3432 cm−1 (vibrations due to −NH and −OH). The coefficients of friction for microwave‐assisted and traditional hydrothermal synthesized nanocomposites are 0.22 and 0.34, respectively. The wear depths are 98 microns and 141 microns, with a wear scar diameter of 2.87 mm for g‐C3N4/MoS2‐MW and 3.45 mm for g‐C3N4/MoS2‐HT, indicating superior lubrication with the microwave‐assisted coating. [ABSTRACT FROM AUTHOR]

Organic coatings containing solid lubricants effectively prevent contact between recycled aluminum alloy surfaces and molds, thereby preventing damage caused by impurities. PVB-based easily removable coatings show promise in the stamping industry, but there is scarce research on the interactions of various lubricating additives within easily removable binder systems and their lubrication effects. This paper primarily concentrates on the synthesis of PVB-based composite coatings containing PTFE and MoS2. It delves into the synergistic lubrication mechanism of MoS2 and PTFE on mold steel, as investigated through cupping and tribological tests. The results show that the compounded coating exhibits superior dispersion, lubrication performance, tribological properties, and can withstand higher stamping loads compared to single-component coatings. MoS2 demonstrates exceptional extreme pressure performance and enhances the transfer capability of the coating. PTFE reduces the friction coefficient while minimizing coating adhesion to the die surface. This study provides a theoretical foundation for selecting solid lubricants in organic thin coatings for stamping lubrication. [ABSTRACT FROM AUTHOR]

The main aim of this study was to assess the impact of the environment on the mechanical and tribological properties of glass-carbomer cements used in dentistry. The properties of the Glass Cements Polyalkene (GCP) Glass Fill material, belonging to glass-polyalkene cements, were tested after placing it in various environments: air, distilled water, artificial saliva simulating a neutral environment (pH = 7), and simulating inflammation (pH = 4). The research material included four samples and a two-year reference material. The analysis of volumetric consumption and the assessment of the impact of solubility on the stability of glass-carbomer cements were carried out using tribological measurements and Vickers hardness measurements. In addition, microstructural characterization of the materials was performed using scanning electron microscopy (SEM). It was observed that the lowest wear (0.04%), the most stable microstructure, and the lowest average hardness (21.52 HV 0.1) were exhibited by the material stored in artificial saliva simulating a neutral environment (pH = 7). The least stable microstructure and statistically the highest hardness (77.3 HV 0.1) was observed in the test sample, which was stored in air for two years and then in distilled water. The highest consumption (0.11%) was recorded in the case of cement placed in artificial saliva simulating inflammation (pH = 4). The results obtained in this study indicate specific trends in the influence of the environment in which the tested cement is located, such as air, distilled water, air/distilled water, artificial saliva simulating a neutral environment, and simulating inflammation, on its structure, hardness, and wear. [ABSTRACT FROM AUTHOR]