Search

To achieve the goal of developing high-performance lubricant additives for industrial lubrication. Herein, tetradecylphosphonic acid (TDPA) modified Ti3C2TX and graphene oxide (GO) were used as nanohybrid lubricant additives in the polyalphaolefins base oil (PAO6). The high-speed reciprocating friction and wear test shows that TDPA–Ti3C2/GO is an efficient friction-reduction and antiwear additive. The base oil mixed with 0.05 wt%TDPA–Ti3C2/0.05 wt% GO exhibits the lowest coefficient of friction (COF) and wear rate with the value of 0.09 and 4.4 × 10–6 mm3/Nm, decreased by 54.5 and 90.0% compared with pure PAO6 oil, respectively. Detailed characterization analysis shows that the tribological film of the modified TDPA–Ti3C2/GO nanohybrids oil-lubricated surface was mainly composed of PAO6, TDPA, GO, and iron oxide. This indicates that the friction-reduction and antiwear mechanism of TDPA–Ti3C2/GO in base oil lies in the adsorption of the two nanomaterials and the formation of a self-lubricating film on the rubbing interface. This study provides a new approach to the design of nanohybrid lubricant additives and creates new prospects for the application of nanomaterials in tribology. [ABSTRACT FROM AUTHOR]

In the analysis of tribological contacts, the focus is often on a singular question or result. However, this entails the potential risk that the overall picture and the relationships could be oversimplified or even that wrong conclusions could be drawn. In this article, a comprehensive consideration of test results including component and lubricant analyses is demonstrated by using the example of rolling contact. For this purpose, thrust cylindrical roller bearings of type 81212 with unadditized base oils were tested in the mixed-friction area. Our study shows that by using an adapted and innovative surface analysis, a deeper dive into the tribo-film is feasible even without highly sophisticated analytical equipment. The characterization of the layers was performed by the three less time-consuming spatially resolved analysis methods of µXRF, ATR FTIR microscopy and Raman spectroscopy adapted by Schaeffler. This represents a bridge between industry and research. The investigations show that especially undocumented and uncontrolled contamination of the test equipment could lead to surprising findings, which would result in the wrong conclusions. Simple substances, like hydrocarbons, are demanding test specimens. [ABSTRACT FROM AUTHOR]

Developing functional additive resistant to space atomic oxygen (AO) irradiation through simple molecular design and chemical synthesis to enhance the lubricating performance of multialkylated cyclopentanes (MACs) oil is a significant challenge. Herein, sulfur-containing polyhedral oligomere silsesquioxane (POSS) were synthesize via a click-chemistry reaction of octavinyl polyhedral oligomeric with alkyl sulfide. The reduce-friction (RF), anti-wear (AW) properties and anti-AO irradiation of POSS-S-R as MACs base oil additives in atmospheric and simulated space environments were systematically investigated for the first time. Results demonstrate that POSS-S-R not only possesses outstanding anti-AO irradiation capacity but also effectively improves the RF and AW of MACs in atmospheric or simulated space surroundings. This improvement is due to the excellent anti-AO irradiation properties of the POSS structure itself and the high load-carrying ability of silicon-containing and sulfur-containing compounds generated by tribo-chemical reactions, which effectively separates the direct contact of the friction interface. We believe that this synthesized POSS-S-R is a promising additive for space lubricants. [ABSTRACT FROM AUTHOR]

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

Due to their encouraging results, nanolubricants have been revolutionary in the field of lubrication. The degree, to which the new material may improve the tribology, energy savings, and durability, is a crucial consideration for any new additive to a conventional lubricant. The results of the earlier research on carbon, metal, metal oxide, and their composites and hybrid nanolubricants as well as their effects on tribology, are summarized in this review paper. The most popular measuring methodologies, the tribology results for lubricants with an oil base, biodegradable base, and a water base, as well as the reasons that explain these tribological advancements, are all included in this study. Finally, prospects for more study in this area are emphasized. [ABSTRACT FROM AUTHOR]

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

Abnormal wear of the cylinder liner and piston ring in a marine diesel engine will lead to the failure of the diesel engine and colossal energy loss. Using lubricating oil additive with good anti-friction and anti-wear properties effectively inhibits the abnormal wear of cylinder liner and piston rings in diesel engine. The potassium borate/graphene (PB/GN) nano-composite lubricant additive suitable for a marine diesel engine was prepared in this study. Its tribological properties in 500 N base oil were investigated using a pin-on-disk tribotester under various loads and temperature. The frictional surface was comprehensively analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), x-ray photoelectron spectroscope (XPS) and Raman to explore the lubrication mechanisms of the PB/GN nano-composite additive. The results indicated that the PB/GN nano-composite additive could substantially improve the tribological performances of 500N base oil. This could be attributed to the good thermal conductivity of graphene and the tribofilms composed of C, FeO, Fe2O3 and B2O3 formed on the worn surface. The synergy of PB and GN enhanced the tribological performances of base oil. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogel coatings have received great attention in the field of such as medical devices, water treatment membranes, flexible electronics, and marine antifouling. However, when it comes to lubrication of hydrogel materials, though it has great potential applications in the field of industrial and medical drag reduction, some restrained properties are urgently needed to overcome for releasing the practical potential. Durability of high lubrication was revealed from the sliding test during the long-term storage, as well as the long-distance sliding. Some variables which possibly affect the lubrication performance were examined to demonstrate that excellent lubricity of the coating would not be easily influenced by load, frequency, friction pair and temperature. The microstructure and mechanical characterization of the lubricative coating indicate that the resistance to harsh running conditions is premised on enough hydration extent and robustness. The formulae of Possion ratio and ball-on-disk contact stress which apply to soft matter were used for calculating contact stress values in tribology tests. Anti-swelling and bio-compatibility are also verified. This work found a route of achieving superior lubrication and coexisting with stability in lubrication, which can be used for drag reduction in medical devices and shipbuilding industry. [ABSTRACT FROM AUTHOR]

Improving the lubricating properties of base oils through additives is a crucial objective of tribological research, as it helps to reduce friction and wear of materials. Molybdenum disulfide (MoS2) is a 2D nanomaterial with excellent tribological properties that is often used as a lubricant additive. Several studies have been conducted on the preparation and utilization of MoS2 and its nanocomposites as lubricant additives. This paper reviews the research progress on MoS2 nanomaterials as lubricant additives. It firstly introduces various synthesis methods of MoS2 nanomaterials while focusing on the preparation of nano-MoS2 as lubricant additives. It then summarizes the dispersion stability of nano-MoS2 in lubricating oils which has been paid extensive attention. Moreover, this paper reviews and discusses the tribological properties of nano-MoS2 and its various composites as lubricant additives. The possible anti-wear and friction reduction mechanisms of nano-MoS2 and its composites are also discussed. Finally, this paper presents the challenges faced by nano-MoS2 additives in the field of lubrication and the prospects for future research in view of previous studies. [ABSTRACT FROM AUTHOR]

In this study, willow catkins/MoS2 nanoparticles (denoted as WCMSs) have been prepared using a hydrothermal method. The WCMSs were modified with oleic acid (OA) to improve dispersion in base oil. The friction and wear properties of WCMSs in liquid paraffin (LP) for steel balls were investigated using a four-ball wear tester. The results have shown that at a high reaction temperature, willow catkins (being used as a template) and urea (being used as a nitrogen resource) can effectively decrease the wear scar diameters (WSDs) and coefficients of friction (COFs). At a concentration of 0.5 wt.%, the WSD and COF of steel balls, when lubricated using LP containing modified WCMS with urea, decreased from 0.65 mm and 0.175 of pure LP to 0.46 mm and 0.09, respectively. The addition of urea and hydroxylated catkins can generate a significant number of loose nano-sheets and even graphene-like sheets. The weak van der Waals forces, decreasing the shear forces that the steel balls must overcome, provide effective lubrication during rotation. On the other hand, the tribo-films containing MoS2, FeS, azide, metal oxides and other compounds play important roles in reducing friction and facilitating anti-wear properties. [ABSTRACT FROM AUTHOR]

MoS2 lithium-based grease is suitable for lubrication protection between bearings at high temperatures and loads due to its excellent tribological properties. However, there is little research on the influence of different addition methods of MoS2 additive on its tribology and corrosion properties. In this work, eco-friendly vegetable oil was selected as the base oil, with MoS2 powder as the additive to synthesize lithium-based grease. The effects of different adding modes of MoS2 on the tribology and corrosion properties of the grease were studied. The experimental results showed that adding 0.01 wt% MoS2 before thickening (Method D) was more conducive to improving the tribological properties of lithium grease. The average friction coefficient was reduced by 26.1%, and the average wear scar diameter was reduced by 0.16 mm. After grinding and adding (Method B) 0.01 wt% MoS2, the corrosion inhibition efficiency of the steel sheet was as high as 96.97%. The reason was that the tribochemical reaction of MoS2 evenly distributed throughout the grease during friction, forming a thin friction film, reducing friction and wear. The protective film formed by MoS2 and GCr15-bearing steel improved the corrosion inhibition performance of the grease. [ABSTRACT FROM AUTHOR]

The forthcoming revolution in mobility and the use of lubricants to ensure ecological friendliness intensifies the pressure on tribology for predictors in new life cycles, mainly addressing wear. The current paper aims to obtain such predictors by studying how the wear processes that occur in a standard FE8 bearing test rig under thin film lubrication are conducted by the properties of the lubricant rather than simple viscosity parameters. Assuming that the activity of a lubricant with respect to the temperature, surface, and chemicals is a matter of its chemical potential, the results show that the nature of the base oil is a key parameter, apart from the chemical structure of the additives. Moreover, it becomes clear that chemical predictors are changing by altering the conditions they are exposed to. As an important result, the lubricant is effective in the prevention of wear if it has the capacity to uptake and transmit electrical charges due to its polarisability during a wear process. [ABSTRACT FROM AUTHOR]

The current global warming challenges have drawn refrigerants with low Global Warming Potential (GWP). R32 (difluoromethane) is the most promising low-GWP refrigerant and is slightly flammable. The addition of a flame retardant to HFC-32 can improve its flammability. Trifluoroiodomethane (R13I1) is a flame retardant with an extremely low GWP that can be employed as a refrigerant component. This experimental study investigates the effect of dispersing aluminium oxide (Al2O3) nanoparticles in the compressor oil with varying concentrations of 0.045, 0.09, 0.135, and 0.18 vol% in the Polyol Ester (POE) oil on its thermal, tribological, and rheological properties as well as on the overall performance of a vapour compression air conditioning system using ultra-low GWP mixture refrigerants consisting of R32, R161, and R13I1 as the working fluid. The thermophysical properties of the mixture refrigerant have been calculated using REFPROP (NIST properties of fluid reference). The mixture refrigerant (R32/R161/R13I1) performed better in alumina nanolubricant and the comparison has been made with reference to the base lubricant (POE) in terms of power consumption, COP, coefficient of friction, and cooling capacity. The results showed that the coefficient of performance (COP) and cooling capacity increased by 32.6% and 11.7%, respectively. The maximum power saving is up to 16.1%, and the coefficient of friction is reduced by 32.4%. The highest recorded thermal conductivity reached 22.5% at 343.15 K and a volume concentration of 0.18%, compared to base oil at 303.15 K. The air conditioning system's performance showed improvement at an optimal concentration of 0.135 vol%. This study provides valuable insights into identifying energy-efficient and low-GWP refrigerant alternatives suitable for air conditioning systems. [ABSTRACT FROM AUTHOR]

An operando analysis method has been established for evaluating the interfacial structure of an adsorbed layer formed by an additive on a metal surface under fluid lubricated conditions. A parallel-face narrow gap viscometer installed in an energy-resolved neutron reflectometer is used to evaluate the change in the interfacial structure under high shear. The viscometer was designed to operate at a high shear rate while maintaining a µm-order constant gap between two parallel surfaces. When an additive-free base oil was sandwiched in the gap, the neutron reflectivity profiles without and with upper surface rotation were the same. This demonstrates that the reflectivity profiles can be accurately measured regardless of whether the upper surface is rotated. When a base oil containing a polymethacrylate-based additive was sandwiched in the gap, both the thickness and density of the adsorbed additive layer in the rotation (shear field) condition were lower than those in the non-rotation (static) condition. This demonstrates that the proposed method can be used to analyse the structural changes in the adsorbed layer formed by an oil additive on a surface. This combination of a neutron reflectometer and narrow gap viscometer is a promising approach to near-future tribological studies. [ABSTRACT FROM AUTHOR]

In this research, a diesel engine lubricant, modified with Multi-Walled Carbon Nanotubes (MWCNTs) was evaluated. Carboxylic group functionalized MWCNTs were dispersed in 15W40 mineral oil for Diesel engines and retaining ring and cylinder sleeve materials from F300 diesel engine were used for tribological tests. The Nanofluid (0.1 0.5 and 1% wt.) rheological behavior was characterized. Nanolubricants with 1% wt and base oil were evaluated on a Pin-on-Disk test. Results suggest both wear rate and coefficient of friction reduction when MWCNTs are used, while no significant rheological properties changes were observed. [ABSTRACT FROM AUTHOR]

This paper presents an analysis based on experimental data for pointing out the behavior of rapeseed oil when it is additivated with a modifier of friction and wear, the nano hexagonal Boron nitride. All tests are done on a four-ball machine, in mild regime. Test parameters were sliding velocity (0.38 m/s, 0.53 m/s, 0.69 m/s, corresponding to the spindle rotational speed of the four-ball machine of 1000 rpm, 1400 rpm, 1800 rpm (±10 rpm),), force (100 N – 300 N), test duration 1 h. There were calculated the average friction coefficient during the test and the average wear scar diameter (WSD) for each test. The same test parameters were done twice and the values in this paper are the average of these two tests. Wear was discussed for the same velocity range, in terms of WSD, but for comparing tests with different sliding velocity (implicitly, different sliding distances), there was used the wear rate of the wear scar diameter. The results on wear parameters, using additivated rapeseed oil, do not show spectacular results for the parameters tested in this study, but underline the “insensitivity” of the lubricants to the variation of the test regime (especially with respect to sliding speed), which is desirable for certain applications. [ABSTRACT FROM AUTHOR]

This study examines the effect of mining pollutants and wear products on the rheological and tribological properties of a lubricating grease working in the microclimate of the Polkowice-Sieroszowice mine belonging to the KGHM Polska Miedź Group (Polkowice, Poland). The material under investigation is a commercial lubricating grease thickened with complex lithium soap, based on mineral oil with a molybdenum disulfide (MoS2) addition. A sample of the grease was taken from one of the friction junctions of a self-propelled drilling jumbo operated in the mine. Comparative tests of the fresh grease and the spent grease were carried out. For the two greases, rheological tests, i.e., dynamic oscillation tests and tests in steady flow conditions, were carried out at a constant shear rate. The rheological tests were conducted using a rotational rheometer. Moreover, the tribological characteristics of the tested greases under different friction junction loads were carried out using a ball-on-disc tribometer. Besides friction resistance, the lubrication ability of the two greases was also evaluated through an analysis of the wear of the steel disks after the friction process. Contour and topographic maps of the wear traces of the discs together with their wear profiles were compared. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) and Tungsten disulfide (WS2) nanoparticles addition to castor oil produce nano lubricants of novel properties. These nanomaterial additives are dispersed thoroughly in the liquid phase and are intended to boost the base fluid's thermo-physical, rheological, and tribological properties. All these properties have been studied by varying concentrations of nanoparticles from 0.05 to 2.5%. The size of both nanoparticles are in the range of <20nm. The density of nano lubricants was found to change with respect to nanoparticle concentration and temperature. The density increases from 0.06 to 0.6% with respect to the increase in concentration and decreases by 4%, for increasing temperature from 25 to 100 o C. A significant (15 %) increase in thermal conductivity with MoS2 nanoparticles in lubricants could be observed while with WS2 nanoparticles only 8 % enhancement was observed. The rheological study suggests that nano lubricants have better dynamic viscosity and shear stress than neat castor oil. A tribology study showed improved lubrication properties of the nanolubricants as compared with base castor oil. The addition of MoS2 and WS2 nanoparticles in castor oil decreased the friction coefficient by 53 % and 42 %, respectively, and reduced the wear scar diameter by 24% and 20 %, respectively, as compared to base castor oil. This study was done to develop nonedible vegetable oil based nanolubricants exploring their potential as emerging lubricants. [ABSTRACT FROM AUTHOR]

Purpose: The evaluation of the haptics of water taps and wear-related changes during usage usually involves time- and cost-intensive testing. The purpose of this paper is to abstract the tribo-system between technical ceramic disks of water tap mixer cartridges to the model level and study the tribological behavior. Design/methodology/approach: The friction and wear behavior was studied by means of an alumina ball-on-original alumina disk setup at different temperatures as well as under dry conditions and under lubrication by different greases. Thereby, the frictional behavior was measured in situ, and the wear losses were analyzed by means of laser scanning microscopy. Findings: It was shown that friction and wear can behave in a contrasting way, whereby one grease might lead to low friction, that is, an easy-going movability of the water tap, but to increased wear losses. The latter, in turn, is an indicator for the usability and service life, which cannot be explained from friction alone. Thereby, the viscosity of the base oil, the grease consistency and additives were identified as relevant grease formulation parameters to allow for fluid film (re-)formation and removal of wear particles. Originality/value: To the authors' best knowledge, this is the first approach to systematically analyze the friction and wear behavior of technical ceramic disks of water tap mixer cartridges in dependency on the temperature as well as the used lubricating grease. This approach is relevant for developing screening test strategies as well as for the selection of lubricants for water tap applications. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0334/ [ABSTRACT FROM AUTHOR]

In this study, copper(II) oxide, titanium dioxide and yttrium(III) oxide nanoparticles were added to Group III-type base oil formulated with overbased calcium sulfonate. The nanosized oxides were treated with ethyl oleate surface modification. The tribological properties of the homogenized oil samples were tested on a linear oscillating tribometer. Friction was continuously monitored during the tribological tests. A surface analysis was performed on the worn samples: the amount of wear was determined using a digital optical and confocal microscope. The type of wear was examined with a scanning electron microscope, while the additives adhered to the surface were examined with energy-dispersive X-ray spectroscopy. From the results of the measurements, it can be concluded that the surface-modified nanoparticles worked well with the overbased calcium sulfonate and significantly reduced both wear and friction. In the present tribology system, the optimal concentration of all three oxide ceramic nanoadditives is 0.4 wt%. By using oxide nanoparticles, friction can be reduced by up to 15% and the wear volume by up to 77%. Overbased calcium sulfonate and oxide ceramic nanoparticles together form a lower friction anti-wear boundary layer on the worn surfaces. The results of the tests represent another step toward the applicability of these nanoparticles in commercial engine lubricants. It is advisable to further investigate the possibility of formulating nanoparticles into the oil. [ABSTRACT FROM AUTHOR]

Lubricant additive plays an important role in reducing the friction and wear for base oil. MAX phase ceramics may have superior advantages for additive application due to their unique nanolayered structure. In this paper, Ti2SnC ceramic is prepared by sintering the elemental mixtures at 1250 °C. In addition, Cu-coated Ti2SnC ceramic is successfully prepared using a chemical plating method for the first time. It is confirmed that the Ti2SnC ceramic has good self-catalytic activity, and a layer of stacking Cu nano-particles can be deposited on the Ti2SnC surface without pretreatment. When the Cu-coated Ti2SnC ceramic powder is doped into PAO10 base oil, the oil can exhibit excellent lubrication properties, where the friction coefficient is as low as 0.095. A layer of tribo-film can be formed during the sliding process when the Cu-coated Ti2SnC ceramic is incorporated into PAO10 base oil, which can reduce the friction coefficient. The superior lubrication properties can be attributed to the synergistic lubrication effect of Ti2SnC ceramic and Cu nano-particles. [ABSTRACT FROM AUTHOR]

As technology progresses, lubricant additives are becoming more prevalent and expanding the application areas of modern tribology. This study aimed to investigate the tribological properties of recently used additive particles and their impact on worm gearbox power consumption. To achieve this, hazelnut oil was chosen as the base oil, and graphite, boric acid (BA), and hexagonal boron nitride (hBN) particles were added in certain proportions. The effect of each additive on the coefficient of friction and wear was investigated under different operating speeds and loads using a pin-on-disc tester. Optimal additive ratios for worm gearbox oils were utilized based on the previous studies, and oils using hazelnut oil as the base were prepared accordingly. The efficacy of the additives was evaluated using a worm gearbox test system. [ABSTRACT FROM AUTHOR]

Si 3 N 4 hybrid bearings are considered the most promising motor bearings due to their characteristics of electrical insulation, high speed, low friction coefficient, and wear resistance, which can better meet the requirements of driving motors of electric vehicles. However, the tribological mechanism between the ceramic-grease-steel complex interface is unclear. Three kinds of greases, namely lithium, polyurea, and calcium sulfonate complex grease, were synthesized from poly alpha olefin 40 as base oil. The effects of grease thickener morphology on the tribological properties of Si 3 N 4 /GCr15 contact surfaces at different slip speeds were investigated, and the vibration and friction torque performances in 6204 hybrid ceramic balls were evaluated. The results showed that the thickener could form physical deposition film and friction film to protect the worn surface at low speed. The friction and wear conditions were significantly improved at high speed under lithium grease and polyurea grease lubrication, being a mixed lubrication state. In presence of lithium grease, the tribological performance of the Si 3 N 4 /GCr15 interface and the vibration performance, impacted condition, starting torque, and friction torque of the hybrid ceramic ball bearings were all the best. Because lithium grease is subjected to continuous shear of the ceramic ball, which releases the base oil stably, and forms a thick oil film with the broken thickener in the center of the raceway, the bearing is in a mild lubrication state. Therefore, for Si 3 N 4 hybrid ceramic ball bearings, lithium grease is a lubricant with good application prospects. [ABSTRACT FROM AUTHOR]

Improving the frictional response of a functional surface interface has been a significant research concern. During the last couple of decades, lubricant oils have been enriched with several additives to obtain formulations that can meet the requirements of different lubricating regimes from boundary to full-film hydrodynamic lubrication. The possibility to improve the tribological performance of lubricating oils using various types of nanoparticles has been investigated. In this study, we proposed a data-driven approach that utilizes machine learning (ML) techniques to optimize the composition of a hybrid oil by adding ceramic and carbon-based nanoparticles in varying concentrations to the base oil. Supervised-learning-based regression methods including support vector machines, random forest trees, and artificial neural network (ANN) models are developed to capture the inherent non-linear behavior of the nano lubricants. The ANN hyperparameters were fine-tuned with Bayesian optimization. The regression performance is evaluated with multiple assessment metrics such as the root mean square error (RMSE), mean squared error (MSE), mean absolute error (MAE), and coefficient of determination (R2). The ANN showed the best prediction performance among all ML models, with 2.22 × 10−3 RMSE, 4.92 × 10−6 MSE, 2.1 × 10−3 MAE, and 0.99 R2. The computational models' performance curves for the different nanoparticles and how the composition affects the interface were investigated. The results show that the composition of the optimized hybrid oil was highly dependent on the lubrication regime and that the coefficient of friction was significantly reduced when optimal concentrations of ceramic and carbon-based nanoparticles are added to the base oil. The proposed research work has potential applications in designing hybrid nano lubricants to achieve optimized tribological performance in changing lubrication regimes. [ABSTRACT FROM AUTHOR]

In today's fast, globalised world, lubrication has become essential in enhancing engine efficiency, including in the marine sector. While the number of fishing vessels increased, so did the environmental pollution issues, due to inefficient engines. An outboard engine oil's tribological, oxidation and thermal conductivity behaviour play a crucial role in improving the quality of an outboard engine's life. In this research, Ti3C2Tx MXene nanoparticles with different interlayer spacing were synthesised via an advanced microwave–hydrothermal approach. Later, the nanoparticles were dispersed in TC-W outboard engine oil to formulate the Ti3C2Tx MXene nanolubricant with different concentrations. The results show that nanolubricant with a 0.01 wt.% Ti3C2Tx MXene concentration with higher interlayer spacing reduced the coefficient of friction, and the average wear scar diameter by 14.5% and 6.3%, respectively, compared to the base oil. Furthermore, the nanolubricant with a 0.01 wt.% concentration of the Ti3C2Tx MXene nanoparticle showed an improvement of 54.8% in oxidation induction time compared to the base oil. In addition, MXene nanolubricant established a more than 50% improvement in thermal conductivity compared to the base oil. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to enhance the characteristics of TiO2 nanoparticles (NPs). Because these NPs stick together easily and are difficult to distribute evenly, they cannot be used extensively in lubricating oils. Altering TiO2 was recommended as an alternate way for making NPs simpler to disperse. Design/methodology/approach: Through dielectric barrier discharge plasma (DBDP)-assisted ball mill diagnostics and modeling of molecular dynamics, TiO2@PEG-400 NPs were produced using the DBDP-assisted ball mill. The NPs' microstructure was examined using FESEM, TEM, XRD, FT-IR and TG-DSC. Using the CFT-1 reciprocating friction tester, the tribological properties of TiO2@PEG-400 NPs as base oil additives were studied. EDS and XPS were used to examine the surface wear of the friction pair. Findings: Tribological properties of the modified NPs are vastly superior to those of the original NPs, and the lipophilicity value of TiO2 NPs was improved by 200%. It was determined through tribological testing that TiO2@PEG-400's exceptional performance might be attributable to a chemical reaction film made up of TiO2, Fe2O3, iron oxide and other organic chemicals. Originality/value: This work describes an approach for preventing the aggregation of TiO2 NPs by coating their surface with PEG-400. In addition, the prepared NPs can enhance the tribological performance of lubricating oil. This low-cost, high-performance lubricant additive has tremendous promise for usage in marine engines to minimize operating costs while preserving navigational safety. [ABSTRACT FROM AUTHOR]

In the present study, various properties, viz. physiochemical, rheological, tribological and thermal properties of polyolester (POE) lubricant, a widely used lubricant in household refrigerator compressor, is evaluated by loading it with alumina nanoparticles and also blending it with sesame oil (SESO)—an environment-friendly lubricant and the results are compared in order to visualize the effects. The mass fraction of alumina nanoparticles used is from 0.05 to 0.15% and the blend ratio of sesame oil is from 12.5 to 87.5%. The rheological properties were evaluated for the temperature ranges from 25 to 100 °C. High-frequency reciprocating rig is used to perform tribological studies. The results show that the values of viscosity, viscosity index, flash and fire point enhanced for all the synthesized lubricants with an increase in alumina nanoparticles proportion and the sesame oil ratio in the base POE oil and all of the synthesized lubricants showed Newtonian behaviour as well. The thermal stability (TGA results) of the POE + SESO blend and POE + Al2O3 nanolubricant was found increasing with the increase in the proportion of sesame oil and the alumina nanoparticles in the base POE oil. The contact angle and surface tension of the synthesized lubricants were initially found decreasing with the addition of sesame oil and alumina nanoparticles to the base POE oil and then increased, as the sesame oil and alumina nanoparticles proportion in the base oil approached the maximum limit. Among the POE + Al2O3 nanolubricants, the POE + 0.125%Al2O3 and among the POE + SESO blend 15POE + 25SESO exhibited much better results in tribological studies. The sesame oil-blended POE oil was found less toxic and more biodegradable when compared to the POE + Al2O3 nanolubricant. [ABSTRACT FROM AUTHOR]

Four oil‐soluble ionic liquids (ILs) with different structures were synthesised: N88816‐Doss (N/S), P88816‐Doss (P/S), N88816 phosphate (N/P) and P88816 phosphate (P/P). The effects of the four ILs synthesised with conventional lubricating additives isobutylene sulfide (T321), zinc dialkyl dithiophosphate (ZDDP) and tricresyl phosphate (T306) as PAO10 additives on the physicochemical properties of the prepared oil samples were systematically investigated at the same dosing rates. The antifriction and antiwear properties and extreme pressure performance of oil samples prepared by four ILs and three conventional additives were investigated by a four‐ball friction and a wear testing machine. The results showed that P/S improved the thermal stability of PAO10. The addition of N/S significantly improved the tribological performance of PAO10 at room temperature and under heavy loading. The coefficient of friction was reduced by 90%, the wear spot diameter is decreased by 28%, the last non‐seizure load PB is doubled, and the resistance to sintering did not improve. [ABSTRACT FROM AUTHOR]

The dispersion stability of carbon-based solid lubricants/lubricating oils remains a challenge to overcome. Recently, novel processing routes were developed to obtain 2D turbostratic graphite particles via solid-state reactions between B4C and Cr3C2 (GBC) and between SiC and Fe (GSF) that present outstanding tribological properties in a dry scenario, as well as functionalized graphene (GNH). This work investigated the suspension stability of GBC and GSF particles (0.05 wt.%) dispersed in a low-viscosity polyol ester lubricating oil and their tribological performance. Ammonia-functionalized graphene (GNH) particles were also used as a reference. In order to evaluate the dispersion stability, in addition to the classical digital image technique, a much more assertive, reliable, quantitative and rarely reported in the literature technique was used, i.e., the STEPTM (Space and Time-resolved Extinction Profiles) technology. Reciprocating sphere-on-flat tribological tests were carried out, in which before contact, 0.2 μL of pure oil and suspension (POE + 0.05 wt.% of solid lubricant) was applied on a flat surface. The results showed that the GBC particles remained remarkably stable and reduced the sphere wear rate by 61.8%. From the tribosystem point of view, the presence of GBC and GSF reduced the wear rate by 18.4% and 2.2%, respectively, with respect to the pure oil, while the GNH particles increased the wear rate by 4.2%. Furthermore, the wear rate was improved due to the highly disordered carbon tribolayer formation identified on both surfaces. [ABSTRACT FROM AUTHOR]

According to the redox ability of dopamine in a weak alkaline environment, silver nanoparticles were uniformly loaded on the surface of polydopamine-modified graphene oxide (Ag/PGO). The results show that the base oil containing Ag/PGO nanoparticles exhibits a better tribological property than base oil. The maximum decrease in wear rate and friction coefficient at different temperatures amounted to 68% and 53.6%, respectively. The tribofilm containing C, O, N, and Ag exists and plays an important role in reducing friction and increasing wear resistance. Molecular dynamics simulations show that the microscopic oil film composed of Ag/PGO and n-hexadecane has low shear deformation during the shearing process, and the oil film has low interaction energy with the upper and lower shear walls. [ABSTRACT FROM AUTHOR]

As one of the important friction pairs of a diesel engine, the cylinder-liner piston ring (CL-PR) faces a harsh high-temperature working environment. To explore the mapping relationship between the friction performance of the CL-PR and the change in temperature, the reciprocating-friction and wear-testing machine was used to analyze the friction performance and lubrication performance of four kinds of lubricating oil at different temperatures (room temperature, 60 °C, 90 °C, and 120 °C) from the friction coefficient, contact resistance and surface topography. The results show that the tribological properties of the four lubricating oils show different trends with the increase in temperature. The friction coefficient of the base oil first decreases and then increases with the increase in temperature; this shows that the friction property of the base oil is improved by a certain temperature rise, and the increase in temperature promotes the formation of an oxide film and reduces the friction coefficient. While the friction coefficient of other three lubricating oils with specific application scenarios increases first and then remains stable, the wear of the friction pair is the most severe at 120 °C. The wear forms are abrasive wear and adhesive wear. [ABSTRACT FROM AUTHOR]

In the boundary lubrication regime, the addition of long as well as straight alkyl chain containing additive exhibit a serendipitous impact on protecting various metallic surfaces or machinery components from friction and subsequent wear. In quest of environment-friendly, proficient friction-reducing, surface protective and cost-effective lubricant additives; herein, two diazomethine functionalised long-chain consisting organic molecules, namely (3E)-N-((E)-2-(octadecylimino)ethylidene)octadecan-1-amine (ODE) and (3E)-N-((E)-2-(dodecylimino)ethylidene)dodecan-1-amine (DDE) were synthesized through a one-pot condensation reaction. The surface protective film-forming, as well as wear and friction reducing properties of these organic additives on steel balls within paraffin oil (PO), were thoroughly explored using a four-ball tester with variation in time, load and speed. The addition of these additives showed a remarkable reduction of coefficient of friction (COF) and wear amount in compared to the pure base oil. ODE exhibited better performance with a ∼62% reduction in COF and ∼23% reduction in wear amount for steels in contact. Electronic level analysis for elucidating the tribofilm formation capability of the additives was rationalized using computational approaches such as density functional theory (DFT) and Fukui indices. Additionally, the molecular dynamics (MD) simulation which is an efficient computational approach was used to explore the spontaneous adsorption insight of additives; and also radial distribution function (RDF) were analysed to impressively explore the molecular-level interactions and adsorption mechanism of the additives with the metal atoms. Thereby, the mechanism of surface adhesive tribofilm formation and its metal protection capability has been explained in a comprehensive manner. Diazomethine functionalised organic molecules were synthesized with a variation of aliphatic chain length. Long aliphatic chain containing ODE additive showed enhanced surface protective performances in paraffin oil exhibiting lower COF value in comparison to DDE. Possible formation of ODE-based efficient tribofilm in metal-solution interface which exhibits enhanced surface adsorption property on the metal surface. Substantial decrease in wear upon addition of ODE in the base oil, which was confirmed by FE-SEM and 3D surface profilometer study. MD simulation has been used to investigate the adsorption competence of ODE and DDE on the iron surface. [ABSTRACT FROM AUTHOR]

With the EU aiming for net-zero greenhouse gas emissions by 2050, conventional production cycles must be transformed into cradle-to-cradle approaches. Spent coffee grounds are often dumped in landfills, with their potential as high-quality feedstock for biofuel or bio-lubricant production. Spent coffee grounds oil (SCGO) was investigated for its physicochemical properties while having more free acid groups compared to the reference polyalphaolefin 8 (PAO 8), which may cause faster oxidation. TGA results displayed comparable thermal stability of SCGO and PAO 8 for inert/oxidative atmosphere. The oil composition was characterized by ATR-FTIR, elemental analysis, and GC-EI-MS, where a higher oxygen content was found for SCGO, referring to functional ester/acid groups. The tribological behavior of SCGO was studied as lubricant base oil and as a 5% additive in PAO 8. The condition of fresh and tribologically used oils was investigated with High-Resolution-ESI-MS, and the worn surfaces were evaluated by light microscopy and topographic analysis. The results showed a superior friction coefficient of pure SCGO (μ = 0.092) to PAO 8 (μ = 0.129). The 5% SCGO additive in PAO 8 (μ = 0.095) could significantly reduce friction compared to pure PAO 8 on an unpolished 100Cr6 surface. [ABSTRACT FROM AUTHOR]

n the last few years, there is a general shift observable toward greener lubrication, fueled amongst others by policy initiatives such as the European Green Deal in consistency with the UN Sustainable Development Goals. At least 70 vol% of a lubricant is composed of a specific base oil, the rest is a variation of additives altering the lubricant properties (enhancing or suppressing existent base oil properties or adding new properties) to be operational for a particular field of application. So, in terms of sustainability, biodegradability, bioaccumulation, and toxicity the type of base oil plays a major role, which makes environmentally harmful petroleum-based lubricant formulations highly problematic for future applications. Hence, this leads to an ever-growing demand of environmentally friendly lubricant alternatives. Within the scope of this review lies the investigation of bio-based, bio-derived, and other sustainable lubricant components that could serve as promising replacements for conventional petroleum-based formulations, in accordance with the principles of green chemistry and tribology. As recycling is embraced by the term sustainability, waste-derived components of non-biological origin are also included in this work. An overview of studies on the tribological performance such as friction and wear properties of these sustainable and benign lubricant components is given. [ABSTRACT FROM AUTHOR]

To develop a high-performance additive that can meet different operating conditions, three liquid crystals (LCs) were developed as additives for a base oil. The structures and thermal stabilities of the obtained LCs were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, mass spectroscopy (MS), and thermogravimetric analysis (TGA). The effects of mesogenic-phase temperature ranges on tribological properties were analyzed using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). UMT-TriboLab friction and wear tester was used to study the friction-reducing properties of LCs. The width of wear marks was observed by a Contour GT-K 3D profiler to illustrate the anti-wear performance of LCs. The friction surface was characterized by scanning electron microscopy (SEM) and Raman spectroscopy. It was demonstrated that, in comparison with the base oil, the addition of LCs caused a remarkable reduction in the coefficient of friction (21.57%) and wear width (31.82%). In addition, LCs show better tribological abilities in the mesogenic-phase temperature ranges. According to the results, we demonstrated that LCs can be used as lubricant additives, especially for several operating conditions under specific temperatures. [ABSTRACT FROM AUTHOR]

Nanoparticles agglomerate easily because of their high surface energy, which seriously reduces their tribological properties as lubricant additives. In this work, the core-shell nanoparticles Ag@polydopamine (PDA) were successfully prepared by the self-oxidation of dopamine hydrochloride on the surface of Ag nanoparticles and the dispersion of Ag nanoparticles in PAO6 was improved to promote anti-wear behaviors. The tribological properties of Ag@PDA nanocomposites as additives in poly alpha olefin (PAO) oil were studied under different concentrations, pressure and speed conditions by UMT-5 tribometer. It was demonstrated that the strong electrostatic repulsion of the PDA structure made the Ag nanoparticles better dispersed in PAO oil, thus playing a better lubricating role. When the concentration of the modified nanoparticles was 0.25 wt%, the friction coefficient of the lubricating oil decreased by 18.67% and no obvious wear was observed on the friction pair surface. When the Ag@PDA content was higher than 0.25 wt%, the tribological performance of the lubricating oil was weakened, which may be due to excessive Ag@PDA acting as an abrasive on the friction surface, thereby increasing friction and wear. The friction coefficient of the lubricating oil containing Ag@PDA decreased with the increase in load, but hardly changed with the increase in frequency. [ABSTRACT FROM AUTHOR]

The purpose of this work is to propose an advanced lubricant model of ILs used as additives to conventional oil. All-atoms molecular dynamics simulations are used to investigate the structure and tribology of oxidatively stable pure imidazolium-based ionic liquids (ILs), branched alkane low friction oil, and a mixture of ILs and oil confined between iron surfaces. Equilibrium and shear simulations are performed at a temperature of 450 K and undergo different applied loads and shear velocities to mimic engine operations. Density profiles reveal the formation of layered structures at the interface. The intensity and number of the density peaks vary according to the composition of the system and the applied pressure. Velocity profiles reveal the presence of no-slip conditions in the pure ILs system and very high slip for the oil. The presence of a stable IL layer at the surface of the mixed lubricant fully reduces the slip of oil. Overall, the mixture displays lower friction in comparison to pure ILs. The formed corrosion protective anion layer on the metal surface makes the mixture a potential candidate for a new generation of high-performance lubricants. [ABSTRACT FROM AUTHOR]

A potential, sustainable, and economical eco-friendly alternative to harmful petroleum-based lubricants is a big challenge for the 21st-century lubricant industry. The present study explores, for the very first time, polysaccharide gums like gum acacia (GA) and guar gum (GG) as additives (0.5–10 %w/w) to enhance the extreme-pressure (EP) performance of greases (based on vegetable oil and organoclay). The greases are evaluated on a four-ball tester for the standard EP test (ASTM D2596). Adding GA or GG to greases enhances EP performance significantly. The performance ameliorates with the gum's concentration showing impressive results at higher concentrations (up to ≈ 60% better than a commercial grease). The superior performance is attributed to an in-situ formed polymer-layered silicate nanocomposite tribofilm at the interface via chemisorption (for GA) or physisorption (for GG). The formulated greases are a possible replacement for existing mineral oil-based commercial greases. [Display omitted] [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) as an additive in fluid lubricants shows desirable features. However, the effects of structural defects in MoS2 on the tribology is ignored under high vacuum. We report that defect-rich MoS2 (DR-MoS2) was used as an additive in perfluoropolyether (PFPE) base oil. The results show that PFPE oil containing 1.0 wt.% DR-MoS2 exhibits significant improvements in reducing friction and anti-wear properties with the minimal friction coefficient (0.116) and wear scar diameter (538 μm) under high vacuum. This work provides a pathway for low-friction lubricants by developing defected 2D material systems. [ABSTRACT FROM AUTHOR]

This study conducted a tribological investigation of base oil (PAO6 and 5W 40) and ionic liquids (IL)-modified lubricants through a four-ball tribometer for 30 min. The lubricants were fabricated via a two-step method using stirring magnetic and ultrasonic dispersion. IL, base oil, and lubricants were, respectively, characterized by XRD and FTIR analysis. In addition, multiple characterizations such as EDS, 3D morphology, and SEM were carried out to evaluate the wear and friction performance of steel balls. Ultimately, the results showed that the coefficient of friction (COF) and wear scar diameter (WSD) of wear scar lubricated by IL-modified lubricants were greatly decreased than that by base oil. IL can well improve the tribological properties of PAO 6 oil and 5W-40 oil due to the tribo-film appearance on the friction surface of wear scar by the effective role of IL. Fascinatingly, this investigation comprehensively and elaborately put a new sight into the lubrication mechanism of how IL reacted with a base oil and enhanced the tribological characteristics. [ABSTRACT FROM AUTHOR]

Recently, energy and environmental crises have aggravated sharply, which results in the eco-friendly and high-efficiency polyethylene glycol (PEG) lubricating oils getting increasingly attention in lubrication. Advancing in PEG-based lubricating oils, especially their high-performance nano-additives is vitally important for energy conservation and reducing pollution. Therefore, a kind of surface and core dual-designed carbon dots (Zn,Cu,Fe-CDs -N) modified by ionic liquid groups ([AMIm][N(CF 3 SO 2) 2 ]) and doped by polymetallic atoms (Zn, Cu, and Fe) were first synthesized and creatively used as the nano-additives for the PEG200 base oil. Adding 1.0 wt% of Zn,Cu,Fe-CDs -N can endow the PEG200 base oil with optimal friction-reduction, anti-wear, and load-supporting performances, the maximal increase amplitudes of approximately 46.6 %, 66.3 %, and 125.0 %, respectively. Additionally, the tribological properties of Zn,Cu,Fe-CDs -N are without any weakening even under high load and long-time operating conditions, exhibiting good practicability and application prospects. Theoretical and experimental studies have illustrated the excellent tribological behaviors of Zn,Cu,Fe-CDs -N assigned to the synergy of film-forming and nano-lubrication effects. [Display omitted] • Polymetallic atom-doped carbon dots modified by ionic liquids were first prepared. • Zn,Cu,Fe-CDs -N as additives for PEG200 showed great tribological behaviors. • Great performance of Zn,Cu,Fe-CDs -N assigned to their multiple lubrication effect. [ABSTRACT FROM AUTHOR]

The main idea of this study was to utilize the pressure and heat produced in the friction process to make Mo nanoparticles mixed in lubrication oil into the multi-layered tribo-film. An in-house developed reciprocating wear rig was used for the tribo-film deposition and associated tribological tests. By design of experiment, the optimal deposition parameter was obtained. Results indicate that the multi-layered film consists of a Mo-based concrete structure layer and a carbon-based film. The carbon-based film was produced by the dehydrogenation and carbonization of the lubricating oil catalyzed with Mo nanoparticles. The consumption and deposition of the carbon-based film was dynamically balanced during the wear process, resulting in the outstanding tribological performance. [Display omitted] • A great amount of Mo nanoparticles were ultrasonically mixed in the base oil. • Film fabricated by utilizing the heat and pressure produced in friction process. • The film consists of Mo-based film mixed with amorphous carbide. • Realize carbon film formation and restoration in lubrication. [ABSTRACT FROM AUTHOR]

Lubrication has become essential in enhancing engine efficiency in the era of rapid globalising. The tribological, oxidation and thermal conductivity properties of an engine oil play a vital role in improving the quality of a vehicle's engine life. In this research, molybdenum disulfide (MoS2) nanoparticle was synthesised via a microwave hydrothermal reactor. Later, the nanoparticles were dispersed in SAE 20W50 diesel engine oil to formulate the nanolubricant. The results show that nanolubricant with 0.01 wt% MoS2 concentration showed the coefficient of friction, average wear scar diameter decreased by 19.24% and 19.52%, respectively, compared to the base oil. Furthermore, the nanolubricant with 0.01 wt% concentration of MoS2 nanoparticle showed an enhancement of 61.15% in oxidation induction time in comparison to the base oil. Furthermore, MoS2 addition within the base oil demonstrates a ~ 10% improvement in thermal conductivity compared to the base oil. [ABSTRACT FROM AUTHOR]

Elastomeric rotary shaft seals are a common seal type for various industrial applications. They are comparably cheap and easy to use and offer an overall good performance. But the wear behavior of these sealing systems is not fully understood and not predictable so far. If a lip seal fails, it causes high maintenance costs and environmental damage. In this article, various tribological conditions are considered. For this purpose, the sealing systems are tested with multiple operating conditions relevant to practice. Three test series are conducted with rotary shaft seals BAUM5X7 75FKM585 on plunge ground shafts. The tests are carried out with two different circumferential velocities of the shaft (4.2 and 10 m/s), three different oil sump temperatures (40, 80, and 120 °C), two different lubricant types (FVA 3 and PG 3), and five different test durations (between 100 and 625 h). For a complete acquisition of the system condition, all shaft surfaces are measured in 2D and 3D before and after the test runs and the wear of the sealing edges is evaluated with a recently developed laser line triangulation method on the complete circumference of the sealing rings. Results show large amounts of wear, depending significantly on the operating conditions. A strong correlation of the wear effects in the tribocontact area of the sealing system becomes evident. This article helps to understand and avoid critical operating conditions concerning abrasive wear. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to improve the dispersion of nanoserpentine modified with OA, KH550 and KH550/oleic acid in lubricating oil. The main aims are to analyze the influence of the dispersion and stability of nanoserpentine modified by different modifiers on the friction properties of lubricating oil. Design/methodology/approach: The nanoserpentine particles obtained by ball-milling were modified by silane coupling agent KH550, OA and KH550/OA, respectively. The dispersity and stability of nanoserpentine in base lubricating oil were characterized by the absorbance value method, centrifuge precipitation rate method and static observation method. The MMU-5G screen display friction and wear tester was used to evaluate the tribological properties of C45E4/C45E4 friction pairs in corresponding lubricating oils. The surface morphology of the friction pairs was observed by scanning electron microscopy and energy dispersive spectroscopy. Findings: The results showed that the dispersity and stability of nanoserpentine particles in lubricating oil were best modified by OA, followed by the KH550/OA and finally, the KH550. Nanoserpentine particles modified with oleic acid showed optimum tribological properties as lubricant additives. Originality/value: This study can improve the dispersion stability of nanoserpentine particles in lubricating oil, increasing the antiwear and antifriction performance of lubricating oil, which has great significance in economic and military aspects. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper reported the tribological behaviours of Cu nanoparticles as lubricant additives. Cu nanoparticles were prepared by an innovative technology called mass‐produced nanoparticles (MPNP). A SRV‐IV friction and wear tester was used to investigate the influence of load on the tribological performance of 0.1 ~ 2 wt% Cu nanoparticles. The results indicated adding 0.1 wt% Cu nanoparticles into PAO6 base oil and 10 W/40 CH‐4 commercial lubricant, reduce the average friction coefficient by 38% and 3%, and decrease the wear rate by 96% and 66% under 300 N, respectively, compared to the lubricants without nanoparticles. The excellent antiwear and antifriction effect could be attributed to the rolling effect caused by the ideal spherical shape and good dispersibility of the prepared Cu nanoparticles and form deposition film on the surface of the friction pair. Therefore, the Cu nanoparticles prepared by MPNP show excellent tribological performance and possess broad prospects in the fields of lubricant additives. [ABSTRACT FROM AUTHOR]

A Nd-YAG laser was used for texturing the Ti6Al4V surface with dimples of diameter 50 and 100 µm and centre-to-centre distance 100, 200 and 400 µm, defining the surface texture density. The tribological evaluation was conducted to analyse and compare the behaviour of un-textured and laser-textured samples under water in comparison to oil (PAO6) lubrication without and with the addition of MoS2 nanotubes into the lubricant. MoS2 nanotubes had a positive effect on friction in both media for laser-textured Ti6Al4V. Evaluation of friction and wear in water and PAO6 showed a comparable tribological response in water to oil for specific laser-textured configurations, proving the novel concept of green tribology for laser texturing in combination with MoS2 nanotubes/water lubrication. [ABSTRACT FROM AUTHOR]

Tribological properties of five anti-wear additives for a steel-copper contact were investigated. It was found that the tribological performances are closely related to the molecular structure of additives. The protic ionic liquid anti-wear additive AW316 exhibits the best tribological performance with the lowest mean friction coefficient of 0.082, and the smallest wear volume, which is more than one order of magnitude smaller than base oil. Transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) tests reveal that a 10–15 nm thickness uniform boundary lubrication film composed of oxides, phosphates, and cuprous oxide was formed on the copper disc, which was responsible for its outstanding tribological performances. [ABSTRACT FROM AUTHOR]