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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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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 MoS2 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]

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]

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]

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]

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]

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]

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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.

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]

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]

This study investigates the enhancement of mechanical and tribological behavior in polymethyl methacrylate (PMMA) composites reinforced with graphene oxide (GO) as a solid lubricant filler for advanced biomedical applications, particularly dental implants. PMMA/GO composites were prepared with varying weight percentages of GO (0, 0.2, 0.5, 0.7, and 1 wt. %) to assess their impact on material performance. A noteworthy improvement in both tensile strength and Young's modulus was detected, reaching up to 141% and 10.6%, respectively, at optimized GO loadings of 1%. Microstructural analysis utilizing scanning electron microscopy for the worn surface revealed enhanced dispersion and interfacial adhesion between GO and the PMMA matrix, reinforcing mechanical coherence. Tribological properties also demonstrated enhancement, with PMMA composites containing 1 wt. % GO exhibiting optimal mechanical and tribological characteristics compared to lower weight fractions. Moreover, microscopic examination revealed a shift in the wear mechanism of the PMMA-GO composite, which was attributed to the lower friction coefficient obtained by GO integration. [ABSTRACT FROM AUTHOR]

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]

This study addresses the pressing need for enhancing the machining performance and hole quality of castamide by investigating the effects of solid lubricant addition and drilling parameters. Castamide, a highly crystalline polyamide synthesized via anionic ring‐opening polymerization, offers superior mechanical, physical, and chemical properties compared to conventional polyamide 6. However, its machining process, particularly drilling, remains a critical challenge due to its viscoelastic nature and sensitivity to heat generation. Using experimental investigations, thrust forces, drilling temperatures, hole geometry, and quality parameters are systematically analyzed and discussed. Notably, the study introduces Kestlub, a modified version of castamide with solid lubricant, and evaluates its drilling performance, a previously unexplored area in the literature. The research employs response surface methodology to model experimental data, considering both linear and quadratic effects of drilling parameters. Additionally, the significance of each parameter is assessed using ANOVA tables and Pareto charts, offering valuable insights into optimizing the drilling process for enhanced hole quality in castamide. It found that optimal drilling conditions occur at low rotational speeds and high feed rates, but thermal damage, influenced by factors like thermal conductivity and transition temperature, affects hole geometry and burr formation. Highlights: Drilling performances of solid lubricant reinforced castamides were investigated.Drilling temperatures were recorded with a thermal camera and differential scanning calorimeter and thermal gravimetric analyses were performed.Drilling properties were analyzed statistically according to the response surface method.It found that optimal drilling conditions occur at low rotational speeds and high feed rates. [ABSTRACT FROM AUTHOR]

The thermal chemical vapor deposition (CVD) process was utilized to fabricate 6H-structured SiC coating dies with carbon control. The carbon-rich clusters along the SiC grain boundaries acted as a pinning site to suppress irregular crystal growth and to homogenize the fine-grained structure. These massive carbon-supersaturated (MCSed) SiC dies with a thickness of 4 mm were utilized for upsetting pure titanium bars in dry and cold conditions. Under a stress gradient from the contact interface to the depth of the SiC coating, the carbon solute isolated from these carbon clusters diffused through the grain boundaries and formed free carbon agglomerates on the contact interface to the pure titanium bars. These in situ-formed free carbon agglomerates acted as a solid lubricant to sustain the friction coefficient at 0.09 at the hot spots on the contact interface and to protect the dies and bars from severe adhesive wearing. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide coatings, particularly Microseal 200-1, have been extensively used as dry film lubricants for actuating mechanisms in space applications. Although Microseal 200-1 has historically been a popular choice for space missions, recent assessments indicate a need for reexamination. This study evaluates sliding friction in air and dry gaseous nitrogen atmospheres at ambient temperatures with both linear reciprocating and rotary unidirectional tribo-tests. Measurements are performed for Microseal 200-1 applied on substrates and surface treatments commonly used in aerospace components, particularly stainless steel and a titanium alloy. Our findings indicate that the friction of stainless steel balls sliding on Microseal 200-1-coated disks is significantly influenced by the environment as well as the disk substrate material. The average friction coefficient ranges from 0.12 to 0.48 in air and from 0.04 to 0.41 in dry gaseous nitrogen, and the amount of friction is consistently much higher for the Microseal 200-1 on the stainless steel than on the titanium alloy. Microscopy and surface analyses, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray fluorescence, of the coatings on stainless steel substrates reveals that the coatings are sparse and relatively thin, likely a key factor contributing to their high friction. This insight underscores the substrate dependence of this widely used coating and highlights the importance of detailed tribological testing in accurately assessing the tribological performance of commercial dry film lubricants, a key step towards improving the reliability and effectiveness of actuating mechanisms for space applications. [ABSTRACT FROM AUTHOR]

Tool surface texturing is a new sustainable method for machining hard-to-machine materials. The present study focuses on the new honeycomb texture (mimic of bee's honeycombs) containing hexagons forming between thin vertical walls. The important novelty in this work is the cutting performance of honeycomb texture on Inconel 713C was examined under cutting parameters and different cooling conditions: dry untextured (T1), dry textured (T2) tool, impregnated solid lubricant (hexagonal boron nitride (hBN)) textured tool (T3), MQL (coconut oil) with textured tool (T4), and NMQL (0.20 wt.% hBN + coconut oil) with textured tool (T5). Compared to plain tools, NMQL to honeycomb texture reduced flank wear by 53.2%, roughness by 43.2%, turning force by 27%, and cutting temperature by 47.7%. Honeycomb texture with MQL (T4) and NMQL (T5) reduces flank surface Ni element diffusion during turning. Nanofluid-textured inserts (T5) demonstrated higher shear angles, lower chip curl diameter, and shorter tool-chip contact length than other conditions. [ABSTRACT FROM AUTHOR]

The loosening or fracture of the prosthetic abutment screw is the most frequently reported complication in implant dentistry. Thin diamond-like carbon (DLC) films offer a low friction coefficient and high wear resistance, functioning as a solid lubricant to prevent the weakening of the implant–abutment system. This study evaluated the effects of DLC nanofilms on the reverse torque of prosthetic abutments after simulated chewing. Abutments with 8° and 11° taper connections, with and without DLC or silver-doped DLC coatings, were tested. The films were deposited through the plasma enhanced chemical vapor deposition process. After two million cycles of mechanical loading, reverse torque was measured. Analyses with scanning electron microscopy were conducted on three samples of each group before and after mechanical cycling to verify the adaptation of the abutments. Tribology, Raman and energy-dispersive spectroscopy analyses were performed. All groups showed a reduction in insertion torque, except the DLC-coated 8° abutments, which demonstrated increased reverse torque. The 11° taper groups experienced the most torque loss. The nanofilm had no significant effect on maintaining insertion torque, except for the DLC8 group, which showed improved performance. [ABSTRACT FROM AUTHOR]

Wind power gears will be excessively worn due to lubrication failure during operation. Herein, the tribological properties of rubbing pairs are improved by filling solid lubricants into surface texture. In texture design, three types of topological textures (Circle (C), Hexagon (H) and Circle/Hexagon (CH)) were obtained by cell topology optimization, and then three cases with 20%, 30%, and 40% density were designed for each texture. Next, SnAgCu and TiC were deposited in texture of AISI 4140 steel (AS) to obtain 9 kinds of self-lubricating surfaces. Among them, AS with 30% CH density (AS-CH30) exhibits excellent mechanical and tribological properties. Compared with AS-C and AS-H, the maximum equivalent stress of AS-CH was decreased by 10.86% and 5.37%, respectively. Friction coefficient and wear rate of AS-CH30 were 79.68% and 78% lower than those of AS. The excellent tribological performances of AS-CH30 can be attributed to the synergistic effect of topological surface and solid lubricants. Topological surface can not only reduce fluctuation of equivalent stress, but also promote the stored lubricants to be easily transferred at the contact interface to form a 200 nm lubricating film containing solid lubricants (mainly), oxides and wear debris. [ABSTRACT FROM AUTHOR]

Inspired by the scales on the surface of crucian carp, the biomimetic fan-shaped textures were designed and prepared on the TC4 contact surface and filled with solid lubricant SnAgCu-Nb2C (SACN). The coupling effects of fan-shaped textures and solid lubricants on the tribological properties of TC4 under variable frequency conditions were investigated. The results indicated that the fan-shaped textures could promote the precipitation of lubricants and provide sufficient lubricants for the worn surface, forming a uniform lubricating film on the worn surface, thus improving the tribological properties. In addition, at the low-frequency stage, the coupling of lubricants and textures had strong adaptability to frequency changes. [ABSTRACT FROM AUTHOR]

Modern engine bearing materials encounter the challenge of functioning under conditions of mixed lubrication, low viscosity oils, downsizing, start–stop engines, potentially leading to metal-to-metal contact and, subsequently, premature bearing failure. In this work, two types of polymer overlays were applied to the bearing surface to compensate for extreme conditions, such as excessive loads and mixed lubrication. Two different polymer overlays, created through a curing process on a conventional engine bearing surface with an approximate thickness of 13 µm, were investigated for their friction and wear resistances under a 30 N load using a pin-on-disc setup. The results indicate that the newly developed polymer overlay (NDP, PAI-based coating) surface has a coefficient of friction (COF) of 0.155 and a wear volume loss of 0.010 cm3. In contrast, the currently used polymer overlay (CPO) in this field shows higher values with a COF of 0.378 and a wear volume loss of 0.024 cm3, which is significantly greater than that of the NDP. It was found that, in addition to accurately selecting the ratios of solid lubricants, polymer resins, and wear-resistant hard particle additives (metal powders, metal oxides, carbides, etc.) within the polymer coating, the effective presence of a transfer film providing low friction on the counter surface also played a crucial role. [ABSTRACT FROM AUTHOR]

This investigation delves into the behavior of copper oxide (CuO) as a solid lubricant inside zirconia toughened alumina (ZTA) ceramic composites. The investigation starts with the preparation of ZTA through co-precipitation followed by powder metallurgy to develop CuO (1.5 wt. %)/ZTA composites. In all cases, hot isotactic pressing is applied for densification. The fully densified samples are thoroughly mirror-polished to investigate the mechanical and tribological properties. A 1.8% reduction in micro-hardness and 6% improvement in fracture toughness are observed with incorporation of CuO into the ZTA matrices. The analysis reveals that the presence of ionic copper at the grain boundary leads to the formation of copper-rich phases, causing a decrease in hardness. However, the softer CuO particles contribute to crack bridging and crack deflection, enhancing fracture toughness. Subsequent investigation into the tribological properties highlights the positive influence of the softer CuO phases acting as a secondary component within the ZTA matrix. A significant enhancement of 39.34% in the Coefficient of Friction (COF) is achieved by incorporating CuO into the ZTA matrix. This improvement can be attributed to the formation of a patchy layer through smearing and squeezing actions on wear debris during sliding. The uniform patchy layer results in smoother and more polished surfaces, leading to an improvement in both the COF and specific wear rate. Further wear analysis reveals various phenomena contributing to surface wear, including pullout of grain particles, micro-fracture, high abrasions, and laminar removal of grains. Overall, the introduction of CuO proves to be beneficial, showcasing improved mechanical and tribological properties in the developed composites, with application in dies, inserts, sparkplugs, etc. [ABSTRACT FROM AUTHOR]

This report deals with the development of a self-lubricated plasma sprayed YSZ/BaF 2 coating taking the following into account: (i) the compatibility of the solid lubricant BaF 2 with YSZ ceramic in terms of wettability, (ii) the homogeneous dispersion of lubricant in the ceramic matrix, and (iii) the measurement of weight fraction of lubricant phase finally retained in the coating microstructure using Rietveld refinement. The YSZ/BaF 2 mix demonstrated excellent flowability, and homogeneous distribution of BaF 2 with a dopant concentration of 15 wt%. The primary purpose of this work is to explore the influence of the spray parameters on BaF 2 phase retention in the YSZ/BaF 2 coatings, and its tribological performance at a high temperature. Under the given parametric conditions, a maximum of 3 wt% of BaF 2 was retained. The YSZ/BaF 2 coating reduced the coefficient of friction and wear rate of YSZ by 39% and 38%, respectively at a temperature of 600 °C. • Synthesis of BaF 2 doped YSZ powder using heterocoagulation technique. • With upto 15 wt% BaF 2 , the YSZ/BaF 2 powder exhibited good flowability. • Deposition of YSZ/BaF 2 composite coatings at different plasma spray parameters. • Retention of maximum 3 wt% of BaF 2 in YSZ/BaF 2 coating at the lowest temperature. • YSZ/BaF 2 coating offered 39% and 38% reduction in friction and wear at 600 °C. [ABSTRACT FROM AUTHOR]

Manufacturing industries work towards the development of low toxic, eco-friendly, and sustainable alternatives to save the ecosystem from the harmful effects of traditional cutting fluids used for machining from long decades. The utilization of solid lubricants in machining is an advance alternative aimed at regulating the temperature in the machining zone without causing environmental pollution. The present study illustrates the machining performance of AISI 52100 steel employing solid lubricant-assisted machining (SLAM). The study evaluates the machining performance of SLAM with respect to cutting forces, vibration acceleration, tool wear, chip morphology, and surface roughness against dry machining (DM). The experimental findings indicate that utilizing SLAM leads to a notable decrease in cutting forces, ranging between 45% to 60%, a reduction in vibration acceleration by 14% to 29%, a decrease in tool wear by 11% to 17%, and a substantial improvement in surface finish ranging from 47% to 66% compared to DM. [ABSTRACT FROM AUTHOR]

Herein, MoS2 solid lubricant is introduced in the form of Mo‐coated MoS2 powder, to enhance the antifriction properties of sintered ferrous antifriction materials (FAMs). The microstructure, phase composition, and tribological properties of Fe–15Cu–0.8C–3.75 (Mo‐coated MoS2) (MC1) are investigated and compared with Fe–15Cu–0.8C (M0) samples, with a discussion on the wear mechanism at a wide temperature range of room temperature to 600 °C. The study reveals that the addition of Mo‐coated MoS2 powders effectively prevents the decomposition of MoS2 during sintering, enhances the bonding strength between MoS2 and the substrate, and significantly improves the hardness of the sintered Fe–15Cu–0.8C samples. In comparison with the sintered Fe–15Cu–0.8C samples, the sintered Fe–15Cu–0.8C–3.75 (Mo‐coated MoS2) samples exhibit good antifriction properties with a frictional coefficient of 0.23 at 600 °C and a wear rate of 6.3 × 10−7mm3 N m−1 at 300 °C. Introducing Mo‐coated MoS2 significantly reduces the average friction coefficient and wear rate of the sintered FAMs at elevated temperatures, attributed to the formation of FeMoO4. The antifriction performance of MC1 samples notably decreases with increasing test temperatures. The main wear mechanism is oxidative wear above 300 °C. [ABSTRACT FROM AUTHOR]

The computer‐aided analysis of microstructure evolution during the sintering process of self‐lubricating ceramic tools can unveil the underlying sintering mechanism and optimize experimental parameters. In this study, a novel self‐lubricating ceramic tool material, Al2O3/SiC/h‐BN@Al2O3, was fabricated with Al2O3 as the matrix, SiC as the reinforcement phase, and h‐BN@Al2O3 as the solid lubricant. The Monte Carlo (MC) method was employed to construct a model of self‐lubricating ceramic tool material, consisting of Al2O3/SiC/h‐BN@Al2O3. Subsequently, the sintering process was analyzed to investigate the influence of particle size and content of reinforced SiC, as well as the content of coated solid lubricant h‐BN@Al2O3, sintering pressure, and temperature on the microstructure of the tool. Optimal composition and sintering parameters were determined: 3 vol% for SiC additive amount with a particle size of 0.05 μm; 5 vol% for h‐BN@Al2O3 additive amount; and an optimal sintering temperature at 1650°C. The development of self‐lubricating ceramic tool materials, Al2O3/SiC/h‐BN@Al2O3, was realized through the employment of the aforementioned parameters. Their mechanical properties and microstructure were comprehensively characterized. The bending strength, fracture toughness, and Vickers hardness of the experimentally‐prepared Al2O3/3 vol%SiC/5 vol%h‐BN@Al2O3 self‐lubricating ceramic tool material were determined to be 722.42 MPa, 6.5 MPa·m1/2, and 20.65 GPa, respectively. [ABSTRACT FROM AUTHOR]

Tribooxidation is the main mechanism to adapt the cutting tool to extreme mechanical and thermal loads during high-speed cutting. Wear and tribooxidation processes in the single layer TiAlCrSiYN and multilayer TiAlCrSiYN/TiAlCrN non-stoichiometric coatings on cutting tools after dry cutting with speed of 500 m/min on the running-in and steady wear stages were studied by the set of modern surface analysis methods. The reasonable preference of the multilayer coating comparing to the single layer one was demonstrated. It was established that oxide films with an amorphous-nanocrystalline structure are formed on the surface of the wear hole. Their composition is close to k Cr2O3, TiO2, Al2O3 (sapphire) and Al2O3 · 2(SiO2) (Mullite 1:2). Prospects of yttrium addition in the complex nitride were estimated by quantum chemical calculations, which has shown that such polyvalent metals as Ti+4, Cr+5,6, Y+4, Al+3 in a multicomponent nitride form a very complex spatially organized electronic structure of double and triple bonds with unoccupied π*-orbitals of nitrogen atoms. Quantum-chemical calculations of the oxidation susceptibility of these coatings with Y microadditions confirmed that this element is more inert than chromium and it is predominantly involved in the formation of interatomic bonds with Al, Ti, Cr affecting the mechanical properties of nitride coatings. [ABSTRACT FROM AUTHOR]

Conventional liquid lubricants prove inadequate for effective lubrication in conditions characterized by high temperatures and high vacuum environments. In such extreme scenarios, powder lubricants emerge as a more viable solution. The present study is to conduct a series of experiments using a reciprocating wear test setup and evaluate the capability of four different machine learning models in analysing the tribological attributes of metals when lubricated with three distinct powder types: zirconium dioxide, copper oxide, and molybdenum disulfide, specifically under conditions of elevated contact pressures and dry environments. The experiments were systematically carried out encompassing a range of load and temperature combinations. Four different machine learning models (MLP, KNN, extreme gradient boosting and light gradient‐boosting machine) were used for predicting the coefficient of friction of metals lubricated with different powders. Extreme gradient boosting machine learning model gives better result than the other models with mean absolute error, root mean squared error, R2 value and average absolute deviation percentage of 0.0215, 0.0278, 0.9962 and respectively. [ABSTRACT FROM AUTHOR]

This article provides an overview of micro-milling operation with a focus on cutting fluids and reviews and discusses dry machining, flood, cryogenic cooling, usage of minimum quantity lubrication (MQL) approach, nanoparticle suspensions, and vegetable oils. In conclusion, the article highlights the future trends and research gaps in field of micro-milling with cutting fluids. Based on works, it can be concluded that researchers explore substitutes for traditional cutting fluids in micro-milling, including vegetable oils, nanofluids, cryogenics, solid lubricants, and de-ionized water. Most cutting fluid studies have focused on micro-milling of aluminum, steel, and titanium, with surface roughness being the most measured output in micro-milling work involving cutting fluids. Overall, the article highlights the need for further research in various aspects of micro-milling operations with cutting fluids, including the development of new cutting strategies, the optimization of cutting fluid delivery methods, and the evaluation of various machinability parameters. [ABSTRACT FROM AUTHOR]

The behavior of a semi‐solid lubricant from insect leg joints is considered and numerical modeling of its tribological properties is performed. It is shown that elementary lubricant fragments, represented by relatively short cylinders, tend to form clots of different sizes and shapes. The simulation results demonstrate that tribosystem with semi‐solid lubricant is capable of maintaining stability and dynamic equilibrium. The importance of maintaining the relative size of clots and their balanced entry and exit from the tribosystem at an optimal level to ensure stable balance and performance of the joint is emphasized. The function of grooves extending from lubricant‐conducting pores is confirmed to facilitate the distribution of lubricant fragments over smooth contact surfaces where the pores are absent. [ABSTRACT FROM AUTHOR]

A solid-liquid composite lubrication coating capable of controlling friction and wear has received widespread attention among researchers. Here, a novel self-lubricating ceramic coating was created through a combination of thermal spraying, hydrothermal reactions, and vacuum impregnation. Its mechanical properties, tribological performance, and self-lubrication mechanism were thoroughly analyzed. The results indicate that the thermally sprayed ceramic coating contained carbon spheres and perfluoropolyether. As a result of the in-situ synthesis of carbon spheres, the coating exhibited enhanced mechanical properties. Compared to the single solid lubricant coating, the solid-liquid composite coating decreased the coefficient of friction by 46.7% to 0.112 and decreased the wear rate from 1.25 × 10−6 mm3/m N to 3.70 × 10−7 mm3/m N. It is proposed in this work that solid-liquid composite coatings can be prepared by utilizing the defects such as pores and microcracks inherent in thermal spray coatings for introducing solid lubricating phases and liquid lubricating phases. This strategy addresses the issue of degradation of the mechanical properties of conventional ceramic-based self-lubricating coatings due to their tribological design. [ABSTRACT FROM AUTHOR]