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Adding rubber made from waste tires to asphalt can promote sustainable development of resources on roads. Molybdenum disulfide, as a nanoscale layered solid lubricant, can enhance the compatibility of rubber-modified asphalt, effectively addressing the issues of high viscosity and poor construction performance of asphalt at elevated temperatures. However, molybdenum disulfide tends to undergo self-agglomeration within the polymer matrix. To address this issue, the present study employed a polyphenol bionic coating method. Modification of molybdenum disulfide was achieved through the codeposition of hydrochloric acid dopamine (DAh) and (3-Mercaptopropyl)trimethoxysilane (MT), resulting in the formation of a bionic coating on its surface (DAh-MT-MoS2). Subsequently, it is blended into the rubber and basic asphalt, followed by further research into the performance of the composite modified asphalt. Microtests validated the superior effectiveness of the bionic coating method, effectively alleviating the self-agglomeration phenomenon of molybdenum disulfide. The research results indicate that the addition of DAh-MT-MoS2 not only improved the temperature sensitivity of asphalt at high temperatures but also reduced the high-temperature viscosity. Furthermore, DAh-MT-MoS2 enhanced the viscoelastic properties of rubber-modified asphalt and helped decrease its deformation sensitivity under varying stress levels, thereby improving its resistance to deformation. Notably, at 46°C, the storage modulus and loss modulus of 0.09% DAh-MT-MoS2/terminal blend (TB) rubberized asphalt (TBRA) increased by 115.0% and 138.9%, respectively, compared with TBRA. The results from the bending beam rheometer and storage stability demonstrate that the addition of DAh-MT-MoS2 effectively enhances the crack resistance of asphalt at low temperatures and improves the storage stability of the asphalt. The addition of an appropriate amount of DAh-MT-MoS2 facilitates sulfur cross-linking reactions within rubber and asphalt, forming a three-dimensional spatial structure where rubber and asphalt are either continuous or intertwined (as observed through fluorescence microscopy). This enhances the bonding between rubber particles and asphalt, ensuring a closer connection. Simultaneously, this significantly retards the thermal decomposition process of asphalt (validated through thermogravimetric analysis), thereby enhancing the heat-resistance performance of rubberized asphalt under high-temperature conditions in summer. [ABSTRACT FROM AUTHOR] more...

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Tribological performance of epoxy (EP) composites reinforced with short glass fibers (SGF), graphite, polytetrafluoroethylene (PTFE), and B4C nanoparticles was investigated under oil lubrication. The effects of different types of SGF, graphite, PTFE, and B4C nanoparticles on the friction and wear properties of EP were examined using a ball-on-block machine. The worn surfaces were characterized using optical microscopy, SEM-EDX, XPS, and TEM. The anti-wear mechanisms were proposed based on the experimental observations and analysis. The results demonstrate that the addition of SGF significantly reduces wear and friction in the EP matrix. In contrast, the incorporation of B4C nanoparticles and other solid lubricants does not have a significant effect on friction and wear. The remarkable tribological properties observed in the SGF-reinforced EP composites can be attributed to the superior load-bearing capabilities and wear durability of SGF. These fibers effectively withstand the load and exhibit excellent durability during sliding, resulting in reduced wear and friction. [ABSTRACT FROM AUTHOR] more...

The use of composite coatings containing solid lubricants is widely reported in the literature, in particular thermally sprayed coatings containing silver. However, these coatings are often limited in their maximum operating temperature due to the melting point of silver and due to reactions between the components at temperatures above 500 °C. In this study, a novel coating is proposed, which consists of an MCrAlY-based matrix and the addition of components (Cu, Mo, and BaF2) to improve the wear resistance at elevated temperatures. The coatings were sprayed by high-velocity oxy-fuel, heat-treated at 1040 °C, and tribologically tested at room and elevated temperatures. Raman spectroscopy and scanning electron microscopy were used on worn and unworn regions of the coating to characterize the changes in microstructure caused by wear. The coatings were also exposed to oxidation and hot corrosion conditions to evaluate the resistance to high-temperature environments. The results have shown an improvement in wear rates of the coatings upon heat treatment and the formation of a smooth tribolayer at 300 °C. The as-sprayed coating was able to withstand the attack by molten salts without exposing the substrate, and minor weight gain was observed, indicating that the MCrAlY matrix was effective to protect the coating and the substrate against damages induced by salt penetration. [ABSTRACT FROM AUTHOR] more...

Due to the unique layered structure and relatively weak interlayer interactions, the MAX phase like Ti 3 AlC 2 shows attractive lubrication potential, but its mechanical properties and wear resistance are insufficient, which is a key factor limiting their widespread application as solid lubrication materials. In this study, the weak interlayer interactions can be strengthened by incorporating the similar crystal structure TiB 2 phase adjacent to the Ti 3 AlC 2 grains. A dense TiB 2 -reinforced Ti 3 AlC 2 composite ceramics were prepared by reactive spark plasma sintering. The coherent interface between the TiB 2 and Ti 3 AlC 2 could be formed, improving the interfacial bonding strength of Ti 3 AlC 2 /TiB 2 composites. Benefiting from the second phase strengthening and grain size refinement, the Ti 3 AlC 2 /TiB 2 ceramics exhibited exceptional high-temperature mechanical and friction properties, including high flexural strength (610 ± 34 MPa), hardness (805 ± 42 HV) and superior wear resistance (∼10−6 mm3/N.m) under loads exceeding 2 GPa at even 800 °C. This work provides an effective strategy for constructing high-strength and wear-resistant MAX-based high-temperature solid lubrication cermets. [ABSTRACT FROM AUTHOR] more...

The performance of a novel hard solid lubricant coating, CrAlNAg, in the face milling operation of AISI 1045 medium carbon steel under the modes of roughing and finishing was investigated. Dry machining was carried out using CrAlN coated inserts with varying silver (Ag) contents ranging from 0 to 16 at.%. The objective was to evaluate the performance of the developed coatings under different machining conditions, which could potentially result in (a) a high material removal rate (rough machining) and (b) high surface finish and dimensional accuracy (finish machining). An in-depth analysis of the cutting forces in face milling was performed to assess the impact of the coatings under these machining conditions. During machining, the force components in the X, Y, and Z directions were measured using a cutting force dynamometer attached to the workpiece. The components of these forces concerning the tool edge were calculated using geometrical characteristics and mathematical formulations, enabling the identification of the true cutting forces and the most sensitive force components relative to the cutting parameters. Apart from cutting forces, chip temperature, tool wear, surface roughness, and chip characteristics were evaluated for different coating compositions under both machining conditions. Owing to superior coating-substrate adhesion and tribological characteristics, the CrAlNAg9 coating with around 8.6 at.% of Ag was found to significantly reduce dominant forces and chip temperature under both machining conditions. Furthermore, the same coating exhibited remarkable resistance to flank wear compared to other compositions of CrAlNAg coatings. [ABSTRACT FROM AUTHOR] more...

Al2O3 with SiC, silver, and graphene nanoplatelets (GNPs) powder mixture was produced by ball milling using ethanol as dispersion media. The GNP-reinforced Al2O3-SiC-Ag ceramic–metal composites were densified by spark plasma sintering technology (SPS). A homogeneous dispersion of GNPs in Al2O3-SiC-Ag was observed from the sintered samples, and the GNPs were embedded between the grains, which resulted in increasing the contact area. The trans-granular mechanism of crack propagation becomes increasingly dominant by adding GNPs. The hardness reaches 27 GPa, as tested by the Vickers microhardness method, which reflects an increase of 11% compared to Ag-GNPs-free Al2O3-SiC. On the other hand, by adding Ag-GNP content, the improvement in density is limited. Wear mechanisms, as determined through ball-on-flat testing, including adhesion, abrasion, and microcracks, are observed and discussed. The composite demonstrated remarkable self-lubricating properties, exhibiting a lower coefficient of friction (COF) and wear rate in an air environment compared to monolithic Al₂O₃-SiC. This improvement is attributed to the formation of a self-lubricating film, enabled by the uniform distribution of Ag and GNPs within the Al₂O₃-SiC matrix. The findings of this study propose a novel material design approach for developing self-lubricating ceramic composites with hybrid solid lubricants. [ABSTRACT FROM AUTHOR] more...

This paper investigates the impact of a CNT-embedded textured tool on the thread-turning process. The study aims to optimize the efficiency and effectiveness of the thread-turning by utilizing this innovative tool. The experimental research explores the performance of the tool in terms of generated cutting forces. The findings contribute to understanding the potential benefits of integrating CNT-embedded textured tools in the manufacturing industry, particularly for thread-turning operations. This study demonstrates that the linear textured tool embedded with CNT solid lubricant exhibits a significant 36.8% reduction in cutting forces compared to conventional cutting inserts. [ABSTRACT FROM AUTHOR] more...

The present study aims to investigate the lubrication potential of the combination of Nickel-doped reduced graphene oxide (rGO-Ni; 0.5, 1.0, 1.5 and 2.0 wt pct) and Ag (10 wt pct) in Spark Plasma Sintered (SPS) Ni-alloy based composites by carrying out tests at 5N load and 0.5 m/s from room temperature (RT) to 800 °C for realizing low friction and low wear which is hitherto unexplored. The doping of rGO with Nickel has been done to improve its wettability with the matrix. Field emission scanning electron microscopy, 3D optical profilometry and X-ray diffraction analysis have been carried out on the worn surfaces to reveal the operating mechanisms of wear. The results indicate that the coefficient of friction (CoF) and wear rate decreased with increasing amount of rGO in the composites and the one having 2.0 wt pct rGO-Ni exhibited the lowest CoF (~ 0.42–0.47) and wear rate (~ 2.84–73.49 × 10−5 mm3/Nm) from RT to 600 °C due to cooperative synergy between the solid lubricants. However, both CoF and wear rate increased from 600 to 800 °C for the composites containing Ag and rGO-Ni due to the probable loss of assistive action between rGO and other lubricating species (silver molybdates or oxides). [ABSTRACT FROM AUTHOR] more...

Yttria-stabilized zirconia and flake graphite c omposite (C/YSZ) coatings were successfully prepared on a TC4 substrate by electrophoretic co-deposition and sintering at 1100 °C using YSZ nanopowder and flake graphite. The effects of the graphite content on the microstructure and friction-wear properties were investigated. The results indicated that flake graphite agglomerated in the C/YSZ coating. The YSZ coating with 0.6wt.% graphite exhibited the highest toughness with the plastic resistance index (H/E) of 0.0172, which was 6.8 % higher than that of the YSZ coating, and effectively inhibited the formation of coating cracks. However, an increase or a decrease in the graphite content led to a decrease in the toughness of the C/YSZ composite coating. The agglomerated graphite in the C/YSZ composite coating acted as a solid lubricant and affected friction and wear properties. The coefficient of friction (COF) of the 0.6C/YSZ sample was 0.45, which was 40 % lower than that of the YSZ sample. The reason for this was that graphite effectively inhibited the falling-off of debris from the coating surface and reduced abrasive wear. However, an excessive amount of graphite, i.e., in case of the 0.8C/YSZ coating, decreased the roughness of the wear surface, leading to a reduction in the H/E and COF by 24.4 % and 29.7 %, respectively. [ABSTRACT FROM AUTHOR] more...

In order to combine the anti-friction performance of micro-texture with the lubrication effect of solid self-lubricating phase, and further improve the tribological performance of the coating under dry friction conditions. Fe5/10%WC/5% MoS2 self-lubricating coating was prepared by laser cladding technology, and then elliptical micro-textures with different arrangement angles (0°, 45°, 90°) were processed on the surface of the coating by laser micro-texture technology. The friction and wear behavior of the micro-texture coating was investigated from the perspectives of friction coefficient, volume wear loss, and wear morphology. The improvement effect of micro-texture on the wear resistance of the coating was discussed, and the synergistic anti-friction mechanism of the self-lubricating coating and surface micro-texture was explored. The results show that the friction coefficient and volume loss of the 0° textured coating are the smallest under the external load of 70 N, and the wear mechanism is characterized by slight abrasive wear. The 45° textured coating exhibits local adhesive traces in addition to a few micro-cutting furrows, suggesting a combination of slight abrasive wear and adhesive wear. The friction coefficient and volume loss of the 90° textured coating are the largest and the volume loss is greater than that of the non-textured coating. The wear mechanism is dominated by fatigue wear, accompanied by slight abrasive wear and adhesive wear. During the friction and wear process, the elliptical micro-pits can promptly capture wear debris, reducing the continuous damage to the coating. Additionally, the solid lubricant (MoS2) stored in the micro-pits can provide continuous lubrication to the friction contact area and effectively decrease the friction coefficient. [ABSTRACT FROM AUTHOR] more...

During shearer operation, the piston rod is susceptible to wear from the invasion of pollutants, thus ruining the sealing ring in the hydraulic cylinder. This work attempts to conduct a systematic investigation of Cu-doped diamond-like carbon (Cu-DLC) film to improve the seal performance. The failure process of the cylinder was analyzed, and relevant parameters were determined. Several Cu-DLC films were deposited on the substrate of the piston rod in a multi-ion beam-assisted system, and their structures and combined tribological performances were investigated. The hardness of the film ranges from 27.6 GPa to 14.8 GPa, and the internal stress ranges from 3500 MPa to 1750 MPa. The steady-state frictional coefficient of the film ranges from 0.04 to 0.15; the wear rate decreases first and then increases, and it reaches its lowest (5.0 × 10−9 mm3/N·m) at 9.2 at.% content. a:C-Cu9.2% film presents optimal combined tribological performances in this experiment. The modification mechanism of Cu-DLC film for the seal performance may come from the synergistic effects of (i) the contact force and friction-heat-induced film graphitization, (ii) Cu doping improves the toughness of the film and acts as a solid lubricant, and (iii) the transfer layer plays a role in self-lubrication. [ABSTRACT FROM AUTHOR] more...

This paper presents possible modifications to the properties of grey cast iron by laser heat treatment. These modifications are analyzed especially with regard to wear properties as a result of graphite content, which is a well-known solid lubricant. Examples of applications of grey cast iron in cases where good wear resistance is required are presented. Laser hardening from the solid state, laser remelting, and laser alloying are characterized. In this study, changes in the surface layer caused by these treatments were analyzed (especially the influence on the microstructure—including graphite content—and wear properties). It was shown that all of these treatments enable the wear resistance of the surface layer to be enhanced, mostly due to the increase in the hardness and microstructure homogeneity. It was also proven that it is possible to retain the graphite phase (at least partially) in the modified surface layer, which is crucial in the case of friction wear resistance. In particular, laser hardening from the solid state does not eliminate graphite. Laser remelting and alloying cause the dilution of carbon from the graphite phase to the melted metal matrix, but, in the case of nodular cast iron, it is possible that not all of the valuable graphite in the surface layer is lost. [ABSTRACT FROM AUTHOR] more...

Though AlTiN coating has been intensively studied, there is still a need to develop AlTiN coating to meet the growing demand of industrial machining. One effective way to improve the performance of AlTiN coating is by adding alloying elements. In this study, AlTiN and AlTiMo coatings were deposited using multi-arc ion plating to investigate the influence of molybdenum addition on the structure, mechanical properties, and cutting performance of AlTiN coatings. Spherical droplets formed on the surfaces of both coatings, with the AlTiMoN coating exhibiting more surface defects than the AlTiN coating. The grazing incidence X-ray diffraction results revealed the formation of an (Al,Ti)N phase formed in the AlTiN and AlTiMoN coatings. Molybdenum doping in the AlTiMoN coating slightly reduced the grain size. Both coatings exhibited excellent adhesion to the substrate. The hardness (H), elastic moduli (E), H/E, and H3/E2 ratios of the AlTiMoN coating were higher than those of the AlTiN coating. The improvement in the mechanical properties was attributed to grain refinement and solution strengthening. Molybdenum doping improved the tribological properties and cutting performance of the AlTiN coatings, which was ascribed to the formation of MoO3 as a solid lubricant. These results show a path to increase the performance of AlTiN coating through molybdenum addition and provide ideas for the application of AlTiMoN coatings for cutting tools. [ABSTRACT FROM AUTHOR] more...

Highlights In the present work, the tribological as well as thermo‐mechanical properties of glass‐filled and carbon‐filled PTFE composites are investigated. Solid lubricants like molybdenum disulfide (MoS2) and graphite are also incorporated in such composites in order to achieve better friction and wear properties. When compared to virgin PTFE, both carbon‐filled PTFE and glass‐filled PTFE composites showed the lowest wear rate. Again, the specific wear rate of glass‐filled PTFE composite was lower as compared to carbon‐filled PTFE composite sample under all test speed. A novel combination of a reinforcing filler (glass fibers) and a solid lubricant (MoS2) incorporated PTFE composite sample [PTFE (90 wt%) + glass fibers (5 wt%) + MoS2(5 wt%)] exhibited the lowest wear rate of the order of 10−9 mm3/Nm which was reduced to around 100‐fold as compared to virgin PTFE under sliding speed of 6.28 m/s. The wear rate was reduced due to the reinforcement of fibers but fibers support the load preferentially, whereas MoS2 and graphite offers a good lubricating effect. The morphological, thermo‐physical and thermo‐mechanical characterization of such composite materials were also carried out using various techniques such as SEM, TGA, DSC, TMA, and DMTA. Such PTFE composites having very good thermo‐mechanical as well as tribological properties have potential to be used as seals, gears, bearings etc. in dynamic aerospace applications. This investigation relates to the PTFE composites to obtain good thermo‐mechanical as well as tribological properties Incorporation of a novel combination of glass fibers and MoS2 exhibited lowest wear rate of the order of 10−9 mm3/Nm The wear property was around 100‐fold lower as compared to virgin PTFE. Such PTFE composites could be used as seals, gears, bearings etc. in dynamic aerospace applications. [ABSTRACT FROM AUTHOR] more...

Cerium oxide (CeO 2) is a primary abrasive frequently used in quartz glass polishing slurry for facilitating glass surface planarisation. However, due to its exorbitant synthesis costs and extremely corrosive as well as toxic reagents in the system, the chemical modification of CeO 2 abrasives have limited practical applications. In this work, a novel chemical mechanical polishing slurry for quartz glass incorporating potassium oleate (KOL), deionised water (DIW), cerium dioxide and molybdenum disulphide (MoS 2) was developed in this paper to enhance the chemical mechanical polishing (CMP) performance of CeO 2 -based polishing slurry. KOL creates an alkaline environment for the system, further develops silicate insoluble substances on the quartz glass surface and boosts the material removal rate (MRR) in CMP. MoS 2 exhibits a two-dimensional layered nanosheet structure between the abrasive and quartz glass, and then acts as a solid lubricant to prevent excessive mechanical damage, thus increasing the abrasive's wettability. This characteristic helps avoid scratches and other defects on the quartz glass surface. Notably, when the content of KOL and MoS 2 in the system is 0.2 wt% and 0.3 wt%, respectively, the surface roughness of the quartz glass surface is 0.48 nm under the scanning area of 15 × 15 μm2 and the MRR is 24.03 μm/h following CMP. The synergistic interaction between CeO 2 and MoS 2 significantly enhances the abrasive performance on the glass substrate, offering a novel approach for developing polishing fluids that leverage the collaborative effects between abrasives and two-dimensional materials. [ABSTRACT FROM AUTHOR] more...

The ability to lubricate and resist wear at temperatures above 600 °C in an oxidative environment remains a significant challenge for metals due to their high-temperature softening, oxidation, and rapid degradation of traditional solid lubricants. Herein, we demonstrate that high-temperature lubricity can be achieved with coefficients of friction (COF) as low as 0.10-0.32 at 600-900 °C by tailoring surface oxidation in additively-manufactured Inconel superalloy. By integrating high-temperature tribological testing, advanced materials characterization, and computations, we show that the formation of spinel-based oxide layers on superalloy promotes sustained self-lubrication due to their lower shear strength and more negative formation and cohesive energy compared to other surface oxides. A reversible phase transformation between the cubic and tetragonal/monoclinic spinel was driven by stress and temperature during high temperature wear. To span Ni- and Cr-based ternary oxide compositional spaces for which little high-temperature COF data exist, we develop a computational design method to predict the lubricity of oxides, incorporating thermodynamics and density functional theory computations. Our finding demonstrates that spinel oxide can exhibit low COF values at temperatures much higher than conventional solid lubricants with 2D layered or Magnéli structures, suggesting a promising design strategy for self-lubricating high-temperature alloys. The authors develop an approach for enhancing the wear resistance and lubricity of metals at elevated temperatures of in oxidative environments, where traditional solid lubricants fail. By engineering surface oxidation in additively manufactured Inconel, they achieve low friction coefficients, between 0.10 and 0.32 at 600-900 °C, through the formation of a spinel-based oxide layer. [ABSTRACT FROM AUTHOR] more...

Various surface modifications to increase the lifespan of cobalt–chromium (CoCr) joint prostheses are being studied to reduce the wear rate in bone joint applications. One recently proposed modification involves depositing graphene oxide functionalized with hyaluronic acid (a compound present in joints) on CoCr surfaces, which can act as a solid lubricant. This paper analyzes the biological alterations caused by wear–corrosion phenomena that occur in joints, both from the perspective of the worn surface (in vitro model) and the particles generated during the wear processes (in vivo model). The analysis of the inflammatory response of macrophage was performed on CoCr surfaces modified with graphene oxide and functionalized with hyaluronic acid (CoCr-GO-HA), before and after wear–corrosion processes. The wear particles released during the wear–corrosion tests of the CoCr-GO-HA/CoCr ball pair immersed in 3 g/L hyaluronic acid were intra-articularly injected into the experimental animals. The hematological analysis in vivo was made considering a murine model of intra-articular injection into the left knee in male adult Wistar rats, at increasing concentrations of the collected wear particles dispersed in 0.9% NaCl. Non-significant differences in the inflammatory response to unworn CoCr-GO-HA surfaces and control (polystyrene) were obtained. The wear–corrosion of the CoCr-GO-HA disk increased the inflammatory response at both 72 and 96 h of material exposure compared to the unworn CoCr-GO-HA surfaces, although the differences were not statistically significant. The pro-inflammatory response of the macrophages was reduced on the worn surfaces of the CoCr modified and functionalized with graphene oxide (GO) and hyaluronic acid (HA), compared to the worn surfaces of the unmodified CoCr. The hematological analysis and tissue reactions after intra-articular injection did not reveal pathological damage, with average hematological values recorded, although slight reductions in creatinine and protein within non-pathological ranges were found. Some traces of biomaterial particles in the knee at the highest concentration of injected particles were only found but without inflammatory signs. The results show the potential benefits of using graphene in intra-articular prostheses, which could improve the quality of life for numerous patients. [ABSTRACT FROM AUTHOR] more...

Great efforts have been made to further reduce friction of atomically thin two-dimensional (2D) materials as solid lubricants due to their exceptional tribological properties and mechanical strength. In this work, the friction of atomically thin graphene is extensively and controllably reduced through pre-rubbing under high stress, resulting in a reduction of the friction coefficient by up to a factor of six compared to the pristine graphene. Also, this reduction can be reversed by reciprocating friction under moderate stress. Furthermore, high-stress pre-rubbing allows for patterning intentionally lubricating features on atomically thin graphene, such as nanometer-sized letters. This reduction in friction is attributed to the decreased sliding potential barrier yet increased contact stiffness, induced by the enhanced strength of graphene adhesion to the substrate due to interfacial charge transfer, as revealed by density functional theory (DFT) calculations. These findings present a practical methodology for optimizing and controlling the performance of 2D materials. This manuscript presents a method for reversible and controllable friction reduction in two-dimensional materials through high-stress pre-rubbing, driven by enhanced graphene adhesion strength to the substrate via interfacial charge transfer. [ABSTRACT FROM AUTHOR] more...

The accumulation of ice on surface has caused great harm to lots of fields such as transportation or aerospace. Nowadays, various equipment or tools used in low‐temperature environments, which face the risk of interface icing, usually have irregular shapes. Traditional rigid anti‐icing materials are difficult to meet practical application requirements. Thus, it is crucial to develop flexible anti‐icing materials that can be applied to various shape surfaces (curved surfaces, flat surfaces). In this paper, a photoelectric synergistic flexible solid slippery surface (FSSS) is prepared by using flexible basalt fiberglass cloth, flexible copper foil, flexible polyurethane/carbon nanotubes mixture, and flexible solid lubricant (the mixture of coconut wax and coconut oil). Even under harsh conditions of the temperature as low as −80 °C, the FSSS exhibits excellent all‐day anti/de‐icing performance whether on flat or curved surface. Moreover, the FSSS shows long‐term stability both on flat and curved surface: situated in air for 60 days, submerged in water for 60 days, kept in acid environment (pH 1) and base environment (pH 13) for 30 days. Besides, the FSSS can also achieve self‐healing function under −80 °C. This flexible surface provides a novel approach for de‐icing/frosting of multi‐shaped objects in the future. [ABSTRACT FROM AUTHOR] more...

Polytetrafluoroethylene (PTFE) is widely used in tribological applications. However, it faces challenges due to its high wear rate. Reinforcement of additives in PTFE reduces its wear rate by up to 10,000 times in dry conditions. Infusing metallic filler materials like Al, Cu, and Pb improves PTFE wear performance but increases the coefficient of friction (COF). However, it may not be suitable for corrosive environments due to potential metal reactivity. Reinforcing PTFE composites with carbon‐based materials reduces weight, improves wear properties, and lowers COF. Pre‐treated materials enhance bonding for improved anti‐friction and anti‐wear properties. PTFE and its composites are widely used in journal bearings, bearing pads, and ball bearings due to their excellent low‐speed, low‐load lubrication properties. They outperform Babbitt alloy in bearing pads, except in heat conductivity. PTFE can also be used as a solid lubricant and can be combined with additives for improved performance. Apart from it, achieving an optimal combination of properties for all forms of reinforcement can be challenging due to the difficulty in determining exact values for multiple properties with specific types of reinforcement. This article provides a comprehensive review that delves into the significant findings pertaining to reinforcement and its application in bearing technology. Highlights: Metals and carbon‐based fillers improve tribo‐properties.Polytetrafluoroethylene (PTFE) provides lubrication and thermal stability to the polymeric materials.Estimation of tribo‐thermal properties in combination is a challenge.Testing conditions greatly impact PTFE composites performance.PTFE as a solid lubricant suitable for low‐speed/load applications. [ABSTRACT FROM AUTHOR] more...

As an excellent solid lubricant in vacuum and inert gas environment, molybdenum disulfide (MoS2) is easy to be oxidized in high temperature, which leads to serious deterioration or even failure of lubricating performance. The introduction of doped phase or composite can improve the high temperature lubricating performance of MoS2-based lubricating coating to some extent. In this work, the effect of nano-particles zinc oxide (ZnO) and layered graphene oxide (GO) on the high temperature (400, 450 and 500 °C) tribological properties of MoS2-based composite lubricating coatings were studied. It was found that the tribological performance of MoS2-ZnO composite coating were the best for almost all test conditions, and the average friction coefficient and wear rate were about 0.25 ~ 0.27 and 4 ~ 6 × 10−5 mm3/Nm, respectively. The promising tribological performance of MoS2-ZnO composite coating was attributed to the ZnO that mitigated the oxidation of MoS2, and the formation of ZnS. It is the formed ZnS, nano-ZnO and a small amount of MoS2 that provided synergistic lubrication. However, the introduction of layered GO deteriorated the tribological properties of the MoS2-based composite coating, due to the high-temperature decomposition of GO and the formation of hard abrasive particles. The results can provide reference for the design and preparation of MoS2-based composite lubricating coating. [ABSTRACT FROM AUTHOR] more...

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

The physical mechanism of self-organization of a multilayer nanolaminated coating based upon non-equilibrium (TiAlCrSiY)N/(TiAlCr)N nitride on a cutting tool during high-speed (600 m/min.) dry cutting of N13 steel is established. Using a set of modern surface analysis methods coating degradation and tribo-oxidation are studied within the running-in and steady stages of wear. It is shown that during cutting, amorphous-nanocrystalline films of oxides similar to Cr2O3, TiO2, Al2O3 (sapphire) and Al2O3 · 2 (SiO2) (mullite) are formed within a wear crater. Using computer calculations by a finite element method, heat transfer is considered in the cutting zone during formation of protective tribo-oxides. It is found that among all tribo-oxides, mullite has the best thermal barrier properties. Oxidation is the main adaptation mechanism of a cutting tool under extreme mechanical and thermal shock during high-speed cutting. The topography of chip contact surface is studied at various cutting stages, which makes it possible to establish a change in plastic deformation mechanisms of treated metal and friction cutting modes. Quantum chemical calculations of the electron structure of mullite show the highest degree of its electron polarization and explain the radical drop in friction coefficient during film formation upon a wear surface. In this case, mullite acts as a solid lubricant. [ABSTRACT FROM AUTHOR] more...

This study highlights the impact of low amounts of MoS2 quantities on composite performance by examining the effects of ultrasonication exfoliated MoS2 at different loadings (0.1–0.5 wt%) on the mechanical and tribological parameters of epoxy composites. Even at low concentrations, the ultrasonication and exfoliation procedures greatly improve the dispersion of MoS2 in the epoxy matrix, enabling its efficient incorporation into the tribofilm during sliding. Optimum mechanical properties were demonstrated by the MoS2/epoxy composite at 0.3 wt%, including a modulus of elasticity of 0.86 GPa, an ultimate tensile strength of 61.88 MPa, and a hardness of 88.0 Shore D, representing improvements of 61.5%, 35.45%, and 16.21%, respectively. Corresponding tribological tests revealed that high sliding velocity (10 N load, 0.2 m/s) resulted in a 44.07% reduction in the coefficient of friction and an 86.29% reduction in wear rate compared to neat epoxy. The enhanced tribological performance is attributed to the efficient removal and incorporation of MoS2 into the tribofilm, where it acts as a solid lubricant that significantly reduces friction and wear. Even though an ultra-low amount of filler concentration was added to the composite, a unique finding was the high MoS2 content in the tribofilm at higher sliding speeds, enhancing lubrication and wear protection. This study establishes that even ultralow MoS2 content, when uniformly dispersed, can profoundly improve the mechanical and tribological properties of epoxy composites, offering a novel approach to enhancing wear resistance. [ABSTRACT FROM AUTHOR] more...

In Caribbean islands, the washing ashore of tons of pelagic Sargassum spp., consisting of two species Sargassum fluitans and Sargassum natans, has been regularly occurring since 2011. As green lubrication is a growing trend in the tribology industry, biochar is a promising alternative. Sargassum biochars, produced from Sargassum pelagic algae, are therefore being studied as solid lubricants. This study aims to explore their potential applications. Biochars from brown algae were pyrolyzed at 400 °C and then annealed at different temperatures (from 600 °C to 1500 °C). The Raman spectra collected on the different biochars showed that there was a structural organization of the biochars as the temperature increased. The tribologic properties of the biochars were studied and compared to a solid lubricant reference (exfoliated graphite). Raman spectroscopy analysis revealed a progressive structural reorganization with increasing temperature, leading to a 58% reduction in the coefficient of friction. The morphology and the structure of the tribofilm are investigated by profilometry, scanning electron microscopy, and Raman microspectrometry. Overall, these results can be considered as a first step for utilizing the biochar derived from brown algae Sargassum sp. as an additive in the lubricant industry, for the purpose of emission reduction. [ABSTRACT FROM AUTHOR] more...

Magnesium silicate hydroxides (MSHs) with granular, schistose, and tubular morphologies were separately incorporated to enhance the tribological properties of phosphate/MoS2 composite coatings. The nano-schistose MSH demonstrated superior tribological performance due to its effective interactions with the worn surface and frictional synergies with solid lubricants. Incorporation of nano-schistose MSH decreased the friction coefficient of composite coatings by about 34.7% and increased the anti-wear performance of composite coatings by about thirteen times. Nano-schistose MSH facilitated the formation of a friction-induced multi-layer heterogenous slipping structure with layered solid lubricants at the friction interface. Moreover, tribo-chemical reactions between nano-schistose MSH and worn surface promoted the in-situ formation of a cermet supporting film, and this also induced the gradual in-situ formation of a lubrication film on the top of worn surface. Consequently, the contact state between tribo-pairs was timely regulated and the invalidation of the nanocomposite slipping structure was effectively restrained during the friction process. As a result, the service life of the phosphate composite coatings was significantly extended and further abrasion on the worn surface was notably reduced. [ABSTRACT FROM AUTHOR] more...

The bonded MoS2 solid lubricant coating is an effective measure to mitigate the fretting wear of AISI 1045 steel. In this work, the amino functionalized MoS2ript> was protonated with acetic acid to make the MoS2 positively charged. The directional arrangement of protonated MoS2 in the coating was achieved by electrophoretic deposition under the electric field force. The bonded directionally aligned MoS2 solid lubricant coating showed high adaptability to various loads and excellent lubrication performance under all three working conditions. At a load of 10 N, the friction coefficient and wear volume of the coating with 5 wt% protonated MoS2 decreased by 20.0% and 37.2% compared to the pure epoxy coating, respectively, and by 0.07% and 16.8% than the randomly arranged MoS2 sample, respectively. The remarkable lubricating properties of MoS2 with directional alignment were attributed to its effective load-bearing and mechanical support, barrier effect on longitudinal extension of cracks, and the formation of a continuous and uniform transfer film. [ABSTRACT FROM AUTHOR] more...

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

Nowadays, AISI 304 stainless steel plays a crucial role in industry. However, stainless steel exhibits limited wear resistance as it is used in parts with relative motion. Laser treatment emerges as a promising approach to improve its superficial properties. Using a laser as a heat source presents unique properties for heating surfaces, as the first atomic layers of the material absorb the radiation from the laser beam. In this study, we used a low-cost 100 W CO2 laser with carbon black powder to treat the surface of AISI 304 steels. In addition, the reflectance of irradiation on steel is 90%. We used carbon black powder as a photo-absorbing material for radiation to overcome this obstacle. The characterization included field emission gun–scanning electron microscopy, energy dispersive x ray, microhardness, and pin-on reciprocation tribometer. The results showed a significant increase in surface hardness after laser treatment compared to the untreated substrate at a magnitude of 3.8 times. Elemental mapping analysis revealed carbon's presence on the substrate's surface. In addition to increasing surface hardness, we observed a decrease in the friction coefficient of the laser-treated samples compared to the reference substrate. Finally, it could be concluded that carbon black powder had a triple function; it acted as a photo-absorbent material, a carbon source to increase surface hardness, and a solid lubricant. These results show the predictions of using a low-cost CO2 laser with carbon black powder as an efficient, versatile, and fast alternative. [ABSTRACT FROM AUTHOR] more...

Solid lubricants are added to polymers to upgrade their tribological properties, especially in cases where adhesive and abrasive friction are valid. However, there are not enough studies on the effects of solid lubricants on particle erosion. This study investigated the effects on solid particle erosion behavior of three different well known solid lubricants (molybdenum disulfide, polytetrafluoroethylene, and graphite). These solid lubricants were added at three different ratios (5, 10, and 15 wt.%) to the two different type (rigid and toughened) epoxy resins. Garnet abrasive particles (180–400 μm) were blasted to the sample surface under 1.5 bar for 15 s to conduct solid particle erosion tests. The erosive wear mechanisms of neat and solid lubricant‐reinforced epoxy resins were investigated in relation to the epoxy type, solid lubricant type, and solid lubricant reinforcement ratio. Statistical analysis was performed according to response surface methodology to support the experimental results, and ANOVA tables were obtained. The wear and deformations that occurred on the surface after solid particle erosion were examined using a noncontact optical profilometer system and scanning electron microscopy, and a significant relationship was detected between the deformation on the surface and particle erosion. Analysis results showed that the factor causing the greatest erosion rate change was the epoxy resin type. Finally, it has been observed that all solid lubricants reduce the erosive wear resistance, and this resistance decreases as the weight ratio increases. Highlights: Investigations were conducted into the erosion behavior of two types of epoxy resins: rigid and toughened. The toughened epoxy resin exhibited greater resistance to erosion. Although it has the same type of content, on average, rigid epoxy worn 2–4 times more than toughened epoxy.The effect of adding polytetrafluoroethylene tended to increase the erosion rate of both rigid and toughened epoxy resin less than that of other solid lubricants.Graphite particles increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times, depending on the value of the reinforcement ratio.MoS2 increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times.Using a noncontact optical profilometer (for investigating surface topography), it was proven that there is a significant relationship between the erosion rate and roughness characteristics. Wear mechanisms were identified by SEM analysis. [ABSTRACT FROM AUTHOR] more...

MAX phase ceramics is a large family of nanolaminate carbides and nitrides, which integrates the advantages of both metals and ceramics, in general, the distinct chemical inertness of ceramics and excellent physical properties like metals. Meanwhile, the rich chemical and structural diversity of the MAXs endows them with broad space for property regulation. Especially, a much higher self‐lubricity, as well as wear resistance, than that of traditional alloys and ceramics, has been observed in MAXs at elevated temperatures in recent decades, which manifests a great application potential and sparks tremendous research interest. Aiming at establishing a correlation among structure, chemical composition, working conditions, and the tribological behaviors of MAXs, this work overviews the recent progress in their high‐temperature (HT) tribological properties, accompanied by advances in synthesis and structure analysis. HT tribological‐specific behaviors, including the stress responses and damage mechanism, oxidation mechanism, and wear mechanism, are discussed. Whereafter, the tribological behaviors along with factors related to the tribological working conditions are discussed. Accordingly, outlooks of MAX phase ceramics for future HT solid lubricants are given based on the optimization of present mechanical properties and processing technologies. [ABSTRACT FROM AUTHOR] more...

In this study, tungsten disulfide–zinc (WS2-Zn) composite films were generated on polyether ether ketone (PEEK) disks by an atmospheric pressure plasma jet (APPJ) equipped with a shrouding attachment. The friction and wear properties of the WS2-Zn coatings were intensively investigated by using a rotational ball-on-disk setup under dry sliding and ambient room conditions. In order to gain more information about the lubrication mechanism, the coating areas as deposited and the worn areas (i.e., in the wear track) were analyzed with a scanning electron microscope (SEM) with regard to their chemical composition in depth by energy-dispersive X-ray spectroscopy (EDS). X-ray photoelectron spectroscopy (XPS) was conducted to obtain precise chemical information from the surface. The results indicated that WS2-Zn coatings significantly improved the tribological properties, exhibiting a coefficient of friction (COF) of <0.2. However, the tribological performance of the coatings is strongly dependent on the plasma process settings (i.e., plasma current, dwell time of the powder particles in the plasma jet), which were tuned to reduce the oxidation by-products of WS2 to a minimum. The COF values achieved of the dry lubricant films were significantly reduced in contrast to the uncoated PEEK by a factor of four. [ABSTRACT FROM AUTHOR] more...

We studied the RbV3Sb5 kagome compound's structural, mechanical, thermal, and optoelectronic properties. Mulliken and Hirshfeld population analysis found ionic and covalent connections in RbV3Sb5. The Born stability criterion shows that pure RbV3Sb5 is mechanically stable. The precise measurement of 3.96 indicates that our sample has higher machinability at 20 GPa. Low anticipated hardness of RbV3Sb5 suggests it can be used as a soft solid lubricant. Hardness ratings rise with pressure, however there are exceptions. Pressure causes large nonmonotonic changes in RbV3Sb5′s anisotropic characteristics. A comparable 20 GPa Zener anisotropic value, RbV3Sb5 has the highest. The structure's projected Debye temperature at 0 GPa is 284.39 K, indicating softness. Dispersion curves with negative frequencies suggest ground state structural dynamical instability. The structure has no negative‐energy phonon branches under 10 GPa stress. From band structure and density of state analysis, the structure behaves metallically under hydrostatic pressure. Also, the structure has maximal ultra‐violet conductivity and absorption. The absorption coefficient, conductivity, and loss function plots show uniform patterns at all pressures. As pressure rises, these graphs’ peaks blue shift. [ABSTRACT FROM AUTHOR] more...

As it is known, Polytetrafluoroethylene (PTFE) is one of the most preferred polymeric materials for tribological applications. This study investigates the performance of PTFE and its composites under different tribological conditions. The effects of short glass fiber (GF), carbon particle (CP) and bronze particle (BP) reinforcement agents and their hybrid filling with molybdenum disulfide (MoS2) on sliding, erosive and abrasive wear were examined. Sliding tests were carried out with a ball‐on‐disc test apparatus, erosive wear tests were carried out with solid particle erosion and abrasive wear tests were carried out with a scratch test. It has been found that reinforcement agents improve sliding and abrasive wear resistance but worsen the erosion resistance. The hardness and contact angle of the samples were associated with their wear performances. Topographic and morphological analyzes of worn surfaces were performed using optical profilometer and scanning electron microscopy (SEM), respectively, and wear mechanisms were discussed. Highlights: Filling materials (glass fiber, carbon particle and bronze particle) increase the adhesion and abrasion resistance of PTFE, while decreasing its erosion resistance.The effect of hybrid addition of MoS2 solid lubricant on wear performances depends on the type of filler.There is a correlation between surface properties (hardness and contact angle) and wear performances.Optical profilometer and scanning electron microscopy were used to examine wear mechanisms. [ABSTRACT FROM AUTHOR] more...

Highlights In polymer‐based dental composites, wear is a three‐body wear system mainly abrasive, because of the food particles and wear products suspended in the oral cavity, which are transferred to the microcavities of the surface of the replacements. Due to this fact, the incorporation of nanodiamond as reinforcement in these polymer–matrix composites, which promotes the creation of a solid lubricant tribofilm surface could be advantageous. With the reinforcement of nanodiamonds, BisGMA/TEGDMA‐based composites increase their microhardness by 95%–420%. A maximum hardness exceeding 65 HV is achieved with a reinforcement of 3.2 wt%. The specific wear rate of neat BisGMA/TEGDMA is near 10−4 mm3/Nm and the Archard's coefficient is 2.6 × 105. The incorporation of a content of 1.6 wt% ND is enough to cause a diminution of ~78% in the friction coefficient and a reduction of the specific wear rate and Archard's coefficient of ~50%. Nevertheless, the addition of relatively high contents reduces the effectiveness of photoinitiation and photocuring, which is related to the scattering and absorption of light radiation by ND. This causes a significant decline in elastic properties starting at 50 μm from the surface. Photocuring polymer resin was successfully reinforced with nanodiamonds. Microhardness increases from 95% up to 420%, close to commercial composites. Friction coefficient and wear rate are reduced with 1.6 wt% nanodiamonds. High levels of reinforcement reduce the effectiveness of photocuring. [ABSTRACT FROM AUTHOR] more...

Enhancing tribological performance through nanostructure control is crucial for saving energy and improving wear resistance for diverse applications. We introduce a new electrochemical approach that integrates aluminum (Al) anodization, tin alternating current (AC) electrodeposition, and anodic MoS2 electrosynthesis for fabricating nanostructured Al2O3/Sn(S)MoS2 composite films on AlSiCu casting alloys. Our unique process uses Sn‐modified MoS2 deposition to form robust solid lubricant MoS2–SnS electrodeposits within the nanochannels and microsized voids/defects of anodic alumina matrix films on the base materials, resulting in a bilayered Al2O3/SnSMoS2 and MoS2–SnS–Sn composite film. The AC‐deposited Sn enhances conductivity in the anodic alumina matrix film, acts as catalytic nuclei for Sn@SnS@MoS2 core‐shell nanoparticles and a dense top layer, and serves as a reductant for the direct synthesis of hybrid solid lubricant MoS2–SnS from MoS3 by anodic electrolysis of MoS42− ions. The resulting nanocomposite film provides a two‐fold increase in lubricity (friction coefficient (COF) μ = 0.14 ⇒ 0.07) and a ten‐fold improvement in wear resistance (COF μ < 0.2) compared to conventional Al2O3/MoS2 film formed by anodizing and reanodizing. The effectiveness of the Al2O3/Sn(S)MoS2 composite is further validated through real automotive engine piston tests. [ABSTRACT FROM AUTHOR] more...

The present work epitomises extracting the graphite (Gr) solid lubricant from the corn stover. The extracted Gr was incorporated as reinforcement in the A356 alloy (Al-7Si), and the effect of the Gr particles on the mechanical and tribological properties was investigated. In spite of this, the input process parameters for the dry sliding wear test at room temperature against the EN31 steel disc were optimised through ANOVA analysis. The fabricated A359—X wt% (X = 0, 2.5, 5, 7.5) composite through bottom pouring stir casting techniques was analysed microstructurally by using XRD and FESEM analysis. The micro Brinell hardness and tensile strength were investigated per ASTME10 and ASTME8M standards. A wear test was performed for the composite pins against the EN31 steel disc according to ASTM G99 specifications. The XRD analysis results depict the presence of carbon (C), aluminium (Al), and silicon (Si) in all the wt% of the Gr reinforcement. However, along with the elements, the Al2Mg peak was confirmed for the A356—7.5 wt% Gr composite and the corresponding cluster element was confirmed in FESEM analysis. The maximum micro Brinell hardness of 92 BHN and U.T.S of 123 MPa and % elongation of 7.11 was attained at 5 wt% Gr reinforcement due to uniform Gr dispersion in the A356 alloy. Based on the ANOVA analysis, the optimal process parameters were obtained at 20 N applied load, 1 m/s sliding velocity, and 1000 m sliding distance for the optimal wear rate of 0.0052386 g/km and 0.364 COF. [ABSTRACT FROM AUTHOR] more...

The effect of an electrospun (ES) film on the reduction of micro-drilling cutting force required for SUS304 plate was investigated. ES films were fabricated using the electrospinning method with polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA) as raw materials. The results of ATR-FTIR spectroscopy showed that there was no difference in the composition of the raw polymers and the fabricated ES films, and that the polymers were not altered. The diameters of the PVA and PMMA nanofibers were approximately 0.069–0.30 and 7.2 μm, respectively. The drill thrust force and run-out when using the nanofiber ES films were lower than those on an uncoated JIS SUS304 plate during the drilling. High-speed camera images showed that PMMA nanofibers pulverized by the cutting process adhered to the drilling tool surface and were guided into the drilling hole. This suggests that ES films made of organic polymer compounds, such as PMMA, are promising candidates for stable drilling, as they suppress drill run-out and act as an excellent lubricant during cutting. more...

Due to their inherent lattice mismatch characteristics, 2D heterostructure interfaces are considered ideal for achieving stable and sustained ultralow friction (superlubricity). Despite extensive research, the current understanding of how interface adhesion affects interlayer friction remains limited. This study focused on graphene/MoS2 and graphene/PdSe2 heterostructure interfaces, where extremely low friction coefficients of ≈10−3 are observed. In contrast, the MoS2/PdSe2 heterostructure interfaces exhibit higher friction coefficients, ≈0.02, primarily due to significant interfacial interactions driven by interlayer charge transfer, which is closely related to the ionic nature of 2D material crystals. These findings indicate that the greater the difference in ionicity between the two 2D materials comprising the sliding interfaces is, the lower the interlayer friction, providing key criteria for designing ultralow friction pairs. Moreover, the experimental results demonstrate that interlayer friction in heterostructure systems is closely associated with the material thickness and interface adhesion strength. These experimental findings are supported by molecular dynamics simulations, further validating the observed friction behavior. By integrating experimental observations with simulation analyses, this study reveals the pivotal role of interface adhesion in regulating interlayer friction and offers new insights into understanding and optimizing the frictional performance of layered solid lubricants. [ABSTRACT FROM AUTHOR] more...

This literature review explores minimum quantity lubrication (MQL) machining, emphasizing its benefits over traditional dry and flooded cooling methods. MQL is vital in manufacturing, enhancing productivity and sustainability. Adding solid lubricants (SL) amplifies MQL's advantages. This article identifies challenges in MQL + SL machining and outlines future research opportunities. A comprehensive four-step review was conducted: identifying research gaps, determining databases and search terms, defining paper selection methods and performing bibliometric analysis. The review abstracted information from selected articles, offering in-depth discussions. Challenges in MQL machining involve forces, temperature, tool wear, roughness and lubricant performance. Studies show incorporating SL into base fluids mitigates these issues. Sustainability is a core focus in modern manufacturing, and MQL's eco-friendly reputation is deserved. MQL with SL, often in nanoparticle form, provides benefits like reduced friction, enhanced tool life, lower energy consumption and improved material disposal. In conclusion, MQL + SL machining offers a promising path to balance productivity and sustainability. Continued research and development are essential to overcome challenges and unlock its full potential. As manufacturing evolves, MQL + SL machining exemplifies innovation and sustainability, poised to reshape the industry's future. [ABSTRACT FROM AUTHOR] more...

Onion-like fullerenes (OLFs) have spherical and tunable shell structures that make them perfect solid lubricants, but their molecular mechanical properties are largely unknown as they are extremely difficult to measure. In this computational study, double-shelled OLFs C60@C180, C80@C180, C60@C240 and C80@C240 are subject to uniaxial elastic strains to obtain their mechanical response. Compressive and tensile elastic moduli are calculated using density functional theory with van der Waals correction. We found that the tensile elastic moduli of the single- and double-shelled fullerenes are always larger than the compressive ones by about 50% to 100%. Inserting C80 into C180 causes an increase in compressive elastic modulus from 96.8 GPa to 178.6 GPa, while inserting C60 into C240 cause much smaller increases. The key factor that determines the stiffening effects is the relative sizes of the inner and outer shells. [ABSTRACT FROM AUTHOR] more...