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The polymeric additives prepared from renewable feedstock having multifunctional applicability attracted significant attention in the lubricant industry. The present research focuses on a comparative study of multifunctional polymeric additives MPA-1 and MPA-2 synthesized via copolymerizing the triglyceride of olive oil and a homopolymer of stearyl methacrylate, respectively, using benzoyl peroxide as a free radical initiator. The synthesized additives were characterized by routine spectroscopic techniques like FT-IR and NMR spectroscopy. In contrast, the molecular weight was determined by gel permeation chromatography (GPC), and thermal stability was analyzed by thermogravimetric analysis (TGA). The additives were also evaluated for rheological analysis using Anton Paar MCR-72 by formulating the additives into mineral base oil (N-150) in three different concentrations, viz. 0.5%, 1.0% and 1.5% w/v. The formulated lubricant was analyzed for physicochemical parameters like viscosity index and pour point by standard ASTM methods. It was observed that both the MPAs additive shows improvement in the physicochemical and rheological properties of the base oil. Thus, the polymeric additives synthesized and formulated with mineral base oil show multifunctional applications. [ABSTRACT FROM AUTHOR]

A simple and accessible method has been developed for the preparation of copper‐containing nanocomposites by thermolysis of a copper(II) complex with a Schiff base based on 3‐formyl‐4‐hydroxycoumarin and octadecylamine at 500 °C. The resulting nanoparticles with a particle size of up to 85 nm were used as additives to lubricants. It has been established that copper oxide nanoparticles with a concentration of 0.5 % and 1 % increase the anti‐wear and anti‐friction properties of the lubricant. [ABSTRACT FROM AUTHOR]

The limited dispersion stability of graphene in lubricating oils and the high cost of chemical deposition method to prepare SiO2/GO composite materials. The samples were analyzed by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, transmission electron microscopy, scanning electron microscope. The test results demonstrate the ideal anchoring of SiO2 materials on GO surfaces. The tribological properties of SiO2/GO nanomaterials as the base oil additive were investigated using a four-ball tribometer. The addition of SiO2/GO nanocomposites to the lubricating oil enhances its lubrication performance, resulting in a significant reduction of 38.6% and 29.7% in friction coefficient and wear scar diameter compared to the base oil. The prominent lubrication properties of SiO2/GO nanocomposites are attributed to their excellent dispersion and ultra-thin shape, which enable them to enter contact surfaces and act as protective films that prevent direct contact with each other. Compared with the previous research, the rheology was innovatively introduced, the rheological test of the lubricating oil was conducted, and its results were correlated with the friction data. The rheological data were fitted to analyze and understand the lubrication mechanism, providing a novel perspective for studying lubricating oils. SiO2/GO composites exhibited excellent performance due to their low cost and lubrication, which is the future direction of commercial lubricant development. It can be extensively utilized in the domains of automotive engines and heavy machinery, which exhibits promising potential applications. SiO2 nanomaterials were grown fully on the layered GO nanoflakes prepared by the sol–gel method, giving rise to a novel microstructure of SiO2/GO as additives materials for lubricating oil. The character of the SiO2/GO is easily deposition on friction interface. [ABSTRACT FROM AUTHOR]

Ti3C2Tx/TiO2 composite materials were successfully prepared by hydrothermal reaction method. The phase structure and morphology of the samples were analyzed by X-ray diffractometer and scanning electron microscope. The results show that TiO2 particles are evenly distributed between the layers and on the surface of Ti3C2Tx nanosheets. The prepared composite materials were added to PAO6 base oil, and the MDW-02 friction and wear testing machine was used to study the effects of material addition concentration, working load and working speed on the tribological properties of lubricating oil. The friction test results show that the introduction of Ti3C2Tx/TiO2 composite material can reduce friction, and the maximum reduction of friction and wear was achieved under additive concentration of 1.0 wt%. By scanning electron microscopy analysis of the wear scars, it was confirmed that the prepared nanocomposites repaired the scratched surface and formed a uniform lubricating film, which helped to improve the tribological properties of the base oil. [ABSTRACT FROM AUTHOR]

The MoO3/GO composites were synthesized via a hydrothermal method. The performance of these composites as lubricating oil additives was investigated by a multifunctional friction testing machine. And the lubrication mechanism of MoO3/GO in base oil was discussed based on SEM and EDS test data. The results demonstrate that MoO3/GO composites as additives exhibit excellent anti-friction and anti-wear properties. This is mainly due to the synergistic effect between the lubricating film formed by the composite material on the wear surface and the self-healing ability of nano-MoO3, which can effectively fill and repair wear scars while reducing friction and wear on the steel disc surface. [ABSTRACT FROM AUTHOR]

This paper has prepared a new type of MoSe2/SnSe2/SnSe@C heterostructure nanocomposites by one-step hydrothermal method and systematically studied by XRD, SEM, and XPS. Furthermore, the tribological behavior of MoSe2/SnSe2/SnSe and MoSe2/SnSe2/SnSe@C heterojunction in pure oil was extensively examined in a ball-on-disk tribometer. The effects of applied load and rotational speed were also investigated. Compared with MoSe2/SnSe2/SnSe nanocomposites, MoSe2/SnSe2/SnSe@C achieved better friction properties. Especially, when the mass ratio of MoSe2/SnSe2/SnSe@C in the base oil is 1.5 wt%, the friction coefficient reaches the minimum value of 0.1. The results show that the introduction of carbon material can significantly improve the wear reduction and anti-wear properties of the matrix in lubricating oil. Additionally, the construction and excellent tribological properties of MoSe2/SnSe2/SnSe@C heterojunction would be beneficial for the design of novel nano-additives with 2D/3D structure for enhancing friction reduction and anti-wear, which also would expand their actual applications in the industry and agriculture. [ABSTRACT FROM AUTHOR]

Nanoadditive with multifunctional properties holds commercial importance in the lubricant industry. Herein, GO‐N‐PPDA was synthesised as nanoadditive by functionalizing graphene oxide (GO) using N‐phenyl‐p‐phenylenediamine and characterised by Fourier transform infrared spectroscopy, X‐ray diffraction analysis, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy analysis. The antioxidant behaviour of GO‐N‐PPDA was analysed by 2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate. The nanoparticles dispersed mineral base oil (N‐250) in 0.2%, 0.4%, 0.6% (w/v) concentrations were evaluated for tribological, rheological and thermophysical analysis by ASTM methods. The flow behaviour of the nanolubricant shows shear thickening behaviour with an increase in shear rate. In contrast, tribological results indicate a significant reduction in wear scar diameter and coefficient of friction to the base oil. Furthermore, GO‐N‐PPDA shows improved thermophysical properties compared with the mineral base oil. Thus, GO‐N‐PPDA shows multifunctional behaviour in terms of viscosity index, pour point, antioxidant activity, rheology and tribological properties. [ABSTRACT FROM AUTHOR]

Lubricating greases are an important class of lubricants to reduce wear and friction in moving components. SP [ sp [[1]] SP ] sp Greases consist of a thickener network which includes base oil and additives of typically low molecular weight. As expected, signals from base oil molecules, thickeners and the alkyl chains of additives were clearly detected in the SP 1 sp H-NMR spectra at 80 MHz. This reveals that additives have a strong influence on the interaction of base oil and thickener and might also affect the thickener and its structure. [Extracted from the article]

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]

The effects of applying external electric fields on the coefficient of friction of a selected elastomer during mechanical interaction with steel and copper surface oil (counter samples) immersed in a pin-on-disc setup were studied and investigated. The synthetic base oils used were PAG 68 and PAO 6. The elastomer selected for the study is commonly used in the manufacture of rotary lip seals. During the investigations, the viscosity of the oils tested was also experimentally determined in the temperature range of between 286 K and 393 K. It was found that the external electric field had a significant effect on the friction coefficient, depending on the type of base oil, the angular velocity of the load force, and the counterpart. It was observed that for both oils tested, the coefficient of friction values decreased by about 30% when an external DC electric field was applied. In addition, a simple numerical model of the friction interface was proposed and studied. The experimental results were complemented by molecular simulations to determine the interaction between the lubricant molecule and the metal surface. Furthermore, molecular models of the metal surface and lubricant molecules were simulated using ReaxFF and COMPASS force fields to determine adsorption energies. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the synergistic friction reduction and antiwear effects of lyophilized graphene loading nano-copper (RGO/Cu) as lubricating oil additives, compared with graphene. Design/methodology/approach: The friction performance of freeze-drying graphene (RGO) and RGO/Cu particles was investigated at different addition concentrations and under different conditions. Findings: Graphene plays a synergistic friction reduction and antiwear effect because of its large specific surface area, surface folds and loading capacity on the nanoparticles. The results showed that the average friction coefficients of RGO and RGO/Cu particles were 22.9% and 6.1% lower than that of base oil and RGO oil, respectively. In addition, the widths of wear scars were 62.3% and 55.3% lower than those of RGO/Cu particles, respectively. Originality/value: The RGO single agent is suitable for medium-load and high-speed conditions, while the RGO/Cu particles can perform better in the conditions of heavy load and high speed. [ABSTRACT FROM AUTHOR]

As an emerging two-dimensional material, MXene exhibits excellent anti-friction and anti-wear properties in lubrication systems. However, as an oil-based lubricant additive, their stable dispersion in base oil still faces great challenges. Optimizing the microstructure has been proved to be an effective strategy to improve the stable dispersion of MXene in base oil. In this work, catechol groups functionalized carbon dots are synthesized successfully by pulsed laser irradiation of tannic acid in acetone, and then they are grafted onto MXene surface to obtain MXene@CDs hybrids via chemical bond between catechol groups of carbon dots and Ti–OH of MXene surface. Carbon dots not only increase the layer spacing of MXene nanosheets, reduce self-weight stacking, but also make it easier to slide between layers. When used as oil based lubricating additives, MXene@CDs can reduce the coefficient of friction of PAO 10 from 0.58 to 0.1, and the wear volume is reduced by 91.3%. Due to the shear-induced and self-healing mechanism, the special intercalation structure of MXene@CDs is easily formed a protective film during the run-in period, which not only reduces the contact area of friction couples but also eliminates the polishing effect on the substrate surface, thus enabling synergistic lubrication. [Display omitted] • Catechol group functionalized CDs are synthesized by pulsed laser irradiation. • MXene@CDs hybrids are prepared by self-assembly of MXene and CDs. • MXene@CDs reduce the COF of PAO from 0.58 to 0.1, the wear volume decreased by 91.3%. [ABSTRACT FROM AUTHOR]

In order to improve the tribological properties of graphene, the synergistic anti-wear and friction reduction effects of alkylated graphene （LTRGO） and organic molybdenum additives was studied. The influence of the additive amount of LTRGO and MoDDP alone and compound on the tribological properties of the base oil was investigated by using the four-ball friction and wear test. The results showed that the compound addition of 0.012wt% LTRGO and 2.0wt% MoDDP had excellent synergistic anti-wear and friction reduction effects. Compared to Formosa Plastics 100N base oil, the average friction coefficient decreased by 38.26%, and the wear scar diameter decreased by 61.79%. In order to meet the requirements of China VI standard for diesel engine emissions, the diesel engine lubricating oil containing LTRGO/MoDTC and MoDTC was formulated, respectively. The results of four-ball test and engine bench test showed that the average friction coefficient and wear scar diameter of the containing LTRGO / MoDTC formulated oil were reduced by 53.49% and 8.84% compared with that of the containing MoDTC formulated oil, respectively, and they were the same as those of Shell CK-4 refined oil products. Under the rated power point condition of the diesel engine, the emissions of CO, HC, particulate matter and CO2 in the engine exhaust using the formulated oil were reduced by 11.76%, 17.39%, 12.93% and 3.46% compared with those of using CK-4 diesel oil, respectively, and only NO increased by 5.71%. It indicates that the synergistic anti-wear and friction reduction effects of LTRGO/MoDTC composite anti-wear additive is obvious, which promotes full fuel combustion and reduces engine emissions. [ABSTRACT FROM AUTHOR]

Self-organization mechanisms of metastable dissipative structures during friction depending on base and oil functional additives for hypoid gears are considered. Research was conducted on a software-hardware complex with simulation of gears' operation in rolling with slipping conditions in start-stop mode. Indicators of formation of wear-resistant dissipative structures include the following: improvement of antifriction characteristics, lubricant boundary layers' formation, contact surfaces' strengthening, and formation of heterogeneous deformation microrelief with a fine-grained structure. The formation of chemically modified boundary layers on 90% of the contact area of tribo-coupling elements ensures an increase in the wear resistance of leading and lagging surfaces by 2 and 1.4 times, respectively. The sclerometry method was used to establish that the formation of dissipative structures when lubricating tribo-coupling elements with various transmission oils can reduce deformation processes in metal near-surface layers by 23%. Highly viscous flavored lubricant with distillate oil and additive composition ensures wear-resistant dissipative structures with active components, including oxygen, sulfur, and phosphorus. [ABSTRACT FROM AUTHOR]

The article describes the results of experimental studies of electrorheological (ER) properties of lubricating oils containing an admixture of an ionic liquid as the electrically active ingredient. The novelty of these studies consists of the use of selected ionic liquids as additives to hydrocarbon oils in order to obtain quasi-homogenous mixtures with electrorheological properties. So far, such studies have not been carried out. Basic research, which consisted in determining the rheological characteristics in the presence of an external direct electric field, was carried out on a specially designed and built stand, which used a modified Brookfield DV-III Ultra viscometer. The conducted research showed that the produced mixtures generated the ER effect in the presence of a direct electric field with an intensity of up to 0.2 kV·mm−1. The tested mixtures showed different electrorheological characteristics. The research was also carried out in the so-called dielectric spectroscopy using the Hewlett Packard HP4192A impedance analyzer. The mechanism of generating and decaying the ER effect was diagnosed by in situ microscopy using the Nikon Eclipse LV100D optical microscope. It was found that the course of the τ = f( γ ˙ ) characteristic of a mixture of hydrocarbon oil with a small admixture of an ionic liquid is mainly influenced by the so-called dielectric properties of the electrically active component, or rather their change as a function of the applied BIAS (DC) voltage. At the same time, the obtained results of the research gave grounds to state that the electrorheological characteristics also depend on many physicochemical properties of the mixture components and on the differentiation of their values e.g., from the difference in viscosity of the insulating base oil and the added ionic liquid, and also from the difference in the value of the surface tension of the base oil and the added ionic liquid. In these studies, it was found that the surface tension of the CJ001 ionic liquid at 25 °C was 26.032 mN·m−1. The surface tension of CJ008 was 28.099 mN·m−1 and that of PAO-6 oil was almost the same, i.e., 27.523 mN·m−1. The first mixture (GP1 + CJ001) showed Bigham characteristics and the second (PAO6 + CJ008) Newtonian, in the second mixture, the viscosity difference of the components was two times lower than in the first one (GP1—12.61 mPa·s, CJ001—552.42 mPa·s and PAO6—47.35 mPa·s, CJ008—327.24 mPa·s). [ABSTRACT FROM AUTHOR]

Purpose: Ball bearings in gas turbine have played a critical role in supporting heavy radial loads but with higher failure rates and repair costs. Therefore, the purpose of this study is to introduce and study a method for their failure analysis with an actual industrial example to guarantee operation reliability and safety. Design/methodology/approach: Spectrometric oil analysis was used as an early abnormal wear indicator, based on which emergent in-use oil replacement was carried out to reduce the wear rate. However, with wear deterioration, further wear failure investigation was conducted by LaserNet Fines and ferrography to detect the imminent wear failure. Finally, with the assistance of elemental analysis of the typical wear particles, the root cause and worn components were determined by scanning electronic microscope and energy-dispersive X-ray spectroscopy. Findings: The results have shown that an extraneous source led to wear failure, which later caused overheat between the outer bearing ring and ball. It is in accordance with visual inspection of the disassembled engine. Originality/value: This method has specified the occasion under which the suitable measurement can be taken. It can achieve the rapid wear condition assessment allowing for root cause and worn parts identification. In addition, wear rate reduction by change of oil can be efficient for most of the time to avoid premature disassemble, especially with the possibility of contamination. It has provided experience to address similar industry-level practical wear failure analysis problems. [ABSTRACT FROM AUTHOR]

Used aviation lubricating oil(UO) as the starting feedstock for the preparation of regenerated base oil by distillation・hydrofining・axlsorption. The properties of UO hydrorefined lubricating oil (HO) were characterized using GC・MS「H NMR and FTIR・ It was found that after the UO was hydrorefined, the viscosity index of HO was 122, and the saturated hydrocarbon content was mass fractions about 92. 26%, the colour code was 2.5, the color code of the regenerated base oil obtained only by the hydrotreating process alone not reached the standard・ Adding 10% clay and stirring at 140 °C for 1.5 h, the viscosity index of regenerated base oil was 125, and the saturated hydrocarbon content was mass fractions about 95%, the colour code was 0・ 3, the quality of the regenerated base oil reached the standard of the base oil VHVI5. The coloring substances in HO are mainly ketones and aldehydes. [ABSTRACT FROM AUTHOR]

The lubricating oil industry is widespread in the world, but getting rid of the used oils has become an environmental concern. Lubricating oils are used in industries and cars but potentially contaminate groundwater after use. This research uses montmorillonite clay to refine old oil treated with acetic acid. Compared to more conventional procedures, the suggested strategy for treating waste oil is more cost-effective due to the relatively inexpensive cost of the acid and the modest process conditions. Water content, sediment content, density, flash and fire points, viscosity, viscosity index, total acid and base number, pour points, and refractive index were among the physicochemical parameters of the treated oil that were examined as a result of this treatment. We analyzed the oils using Fourier transform infrared spectroscopy (FTIR) and atomic absorption spectrometry (AAS). New oil (10w 40), old oil, oil treated with acetic acid, and montmorillonite clay were all put through their paces in a battery of tests. The therapy's physical and chemical alterations were examined across all fields. The findings demonstrated the efficiency of montmorillonite clay due to the strength of the acid to separate the sludge and the lack of compounds hazardous to the environment. The process described here enables recycled oil to be reclaimed as base oil. [ABSTRACT FROM AUTHOR]

Producing lubricating base oils from coal‐based chemicals is an alternative route for replacing the conventional petro‐based lubricants. Herein, we firstly reported the synthesis of high‐viscosity polyalkylphenanthrene oils derived from the coal‐based chemicals (phenanthrene, C6/C8‐olefins) by alkylation with acidic ionic liquid (Et3NHCl∙2AlCl3) as catalyst. Their primary physicochemical properties were studied in detail to reveal their structure–property relationships, the existence of the phenanthrene ring in their molecular structure led to some good property, such as high‐kinematic viscosity (12.6–30.2 mm2·s−1 at 100°C), better flash point (>230°C), high‐oxidative onset time (>230°C) and good polarity. Moreover, the tribological performances of the synthetic oils and the commercial PAO‐20 lubricating base oil were studied for comparison, these alkylated phenanthrenes, especially PHP‐3 and POP‐3, exhibited much higher load‐carrying capacity, reducing friction and anti‐wear property than that observed on PAO‐20. [ABSTRACT FROM AUTHOR]

In this study, new antioxidants were synthesized using (thiol-ene) click reaction where, octane and dodecane thiol were added to styrene which produced from plastic waste as (1:1) mole ratio at rate temperature to obtain the following antioxidant compounds: Octyl(2-phenylethyl) sulfane and Dodecyl(2-phenylethyl) sulfane respectively. Octane and dodecane thiol were also added to p-benzoquinone compound to obtain of the following antioxidant compounds, 2- (Octylthio) benzene-1,4-diol and 2-(Dodecylthio) benzene-1,4- diol respectively. These synthesized antioxidants were added to the lubricating oils such as, engine and hydraulic oils with base oil as a solvent, and then mixed well. Then the characterization of these synthesized antioxidant compounds were specified by using techniques such as, (FT-IR), (NMR) and mass spectroscopy. Then study their efficacy as an antioxidant compounds by using of (FT-IR) and (cyclic voltammetry) techniques. [ABSTRACT FROM AUTHOR]

In lubricated tribo-contacts, hydrogen ingress in steel is possible due to chemical reactions of lubricant components like base oils or additives, and/or contamination upon service particularly water, and/or corrosion processes, and/or electrostatic fields or current flow. Absorbed by the metal, atomic hydrogen may cause serious deleterious effects on the physical–chemical and mechanical properties, reducing the material's ability to withstand the design loads. The present research work is focused on analyzing the influence of electric field on lubricating oils in contact with steel surface. In order to evaluate the possibility of atomic hydrogen generation and permeation into the steel under cathodic polarization of lubricating oils the electrochemical permeation technique developed by Devanathan and Stachurski is used. The input cell of a Devanathan–Stachurski set up is appropriately modified by realizing a very close distance between the working electrode (steel membrane) and a Pt counter electrode with the oil between. This significantly increases the sensibility of the set up and allows the application of larger voltage and higher temperature to enable hydrogen generation from lubricating oils. The complex effects of cathodic polarization, temperature, additives and presence of water in model lubricating oils on atomic hydrogen permeation into steel is discussed. [ABSTRACT FROM AUTHOR]

In this work, TiO2 nanoparticles modified with octadecylamine and dodecyl mercaptan (DDM/ODA@PDA@TiO2 NPs) are uesd to improve the tribological properties of the white oil. The DDM/ODA@PDA@TiO2 NPs which are simply prepared by mussel inspired chemistry and the Michael addition reaction can be facilely dispersed in the white base oil. Tribological measurements showed that the dispersion of the white oil containing 3 wt% DDM/ODA@PDA@TiO2 NPs displays significant reductions in the friction coefficient and wear scar diameter at room temperature and 75°C. Further XPS investigation shows that the favourable tribological properties of DDM/ODA@PDA@TiO2 NPs are ascribed to the synergistic effect of tribofilm (Fe2O3, Fe3O4, FeS2, FeS and FeSO4) and TiO2 nanofluids. [ABSTRACT FROM AUTHOR]

This study is a continuation of analyses of the fluorometric index (FI), based on the fluorescence of substances of oil origin, as an indicator of oil in a seawater column. The effectiveness of the FI in the cold season (late autumn, winter and early spring) for the coastal water in the southern Baltic Sea was assessed. FI was tested for seawater polluted with a mixture of crude oils, lubricating oils and fuels. Laboratory analyses of oil–water systems for low (reaching the limit of detection) oil content in seawater were performed. The influences of the natural components of seawater that disrupt oil detection are discussed. The ability to detect oil in a seawater column regardless of the season was confirmed. [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]

[Display omitted] • AlCl 3 -based ILs with different organic ammonium salts were investigated for naphthalene alkylation. • The Et 3 NHCl-AlCl 3 ionic liquid exhibited better reusability in the alkylation reaction. • The deactivation was related to the protonation ability of ionic liquids. • The decompression treatment achieved the Et 3 NHCl-AlCl 3 ionic liquid for four runs. Lewis acidic ionic liquids as catalysts for alkylation reactions exhibited the potential for industrial application. Herein, the catalytic behavior of AlCl 3 -based ionic liquids with four organic ammonium salts was studied in the alkylation of naphthalene with n-octene for production of lubricating base oil, with special focus on the deactivation and recovery of ionic liquid. The Et 3 NHCl-AlCl 3 ionic liquid exhibited better catalytic performance than others due to its stronger interaction with naphthalene, as evidenced by the adsorption test of naphthalene over ionic liquids. To understand the deactivation mechanism, the deactivated catalysts were extensively characterized by FT-IR and UV–vis. The protonation effect of ionic liquids on polyalkylation products in the presence of HCl was found to aggravate the deactivation of ionic liquid. The negative effect is easily reversed by the decompression treatment on the reaction system before catalyst recovery, this method markedly enhanced the cycling durability of ionic liquids for industrial application. [ABSTRACT FROM AUTHOR]

Steady macroscale superlubricity was firstly achieved on epoxy resin coating lubricated by multiple base oils including nonpolar and polar oils. Hydroxylated tribofilm on counter balls lubricated by multiple base oils was observed by TOF-SIMS spectra. [Display omitted] • Steady macroscale superlubricity was achieved on epoxy resin coating lubricated by multiple base oils. • No obvious run-in stage to superlubricity for the steel/epoxy resin tribopairs lubricated by different base oils. • Soft epoxy resin coating performed superior wear resistance under oil lubrication. • Hydroxylated tribofilm on the counter balls lubricated by multiple base oils was observed by FTIR and TOF-SIMS spectra. Reducing the friction of base oils to a superlubricity state is highly expected at engineering scale. However, it still is a great challenge for the most of viscous base oils to achieve superlubricity on the conventional tribopairs up to now. Here we report the strategy of solid-oil composited lubrication constructed with an ultra-smooth epoxy resin (EP) coating and base oils for achieving superlubricity. Especially, the frictional results showed that the proposed strategy in this study could be suitable for multiple base oils, including nonpolar and polar base oils as lubricants. The friction coefficient of steel/EP tribopair lubricated by the base oils containing hydroxyl group can be as low as 0.001. Meanwhile, the composited lubrication system did not undergo an obvious running-in stage to achieve the superlubricity state regardless of the type of base oils. The surface hydroxylation of the steel counter ball sliding against EP coating was observed by time-of-flight secondary ion mass spectrometer, even when lubricated by nonpolar base oils without hydroxyl group. This could be a critical factor for the base oils to achieve superlubricity. This finding provides a new and facile approach to realize robust superlubrication for different base oils at engineering scale. [ABSTRACT FROM AUTHOR]

Lubricants are indispensable ingredients for alleviating friction and wear in mechanical components especially in automobile. However, due to its poor heat transfer capabilities, traditional lubricants are denatured under extreme working conditions, leading to lubrication failure during the friction process. Therefore, this study elaborately put forward to a novel MoS 2 /h-BN hybrid nanoparticle as efficient nano-additive for engine oil. The results of experiments and molecular dynamics simulation jointly show that compared with mono nanoparticles, hybrid nano-lubricants (NL) thermal conductivity was significantly improved than that of base oil owing to the synergistic effect. The corresponding mechanism for the improving heat transfer performance was suitably proposed based on the Mean Square Displacement (MSD) and Radial Distribution Function (RDF) results at the microscopic atomic level. [Display omitted] [ABSTRACT FROM AUTHOR]

Lubricating additives play a pivotal role in automobiles and industrial machines. The present work describes the design and synthesis of three copolymeric lubricating additives using alkyl acrylates (Ac) and simulated feed containing 33% long-chain α-olefins (LCAO) in n-paraffins. The alkyl acrylates (C6, C10, and C16Ac) and α-olefins are taken in a 1:1 molar ratio, and the three different polymers P1, P2, and P3 are synthesized in a solvent-free medium by the free radical polymerization using benzoyl peroxide (BPO) as initiator. The polymeric additives (P1, P2, and P3) are blended with base oils, and their performances, such as density, pour point, viscosity index (VI), and corrosion properties were studied. The synthesized polymeric additives are miscible with base oils excellently, and they do not change the density of base oil and depress the pour point of the base oils. All the polymeric additives are successful in depressing the pour points of base oils. The pour point of BO-1 is −21, and the use of P1 depresses the pour point to ≤ 27 at 4000 ppm. However, P3 exhibits the best performance even at low concentration (2000 ppm) by depressing the pour point value to ca. 12 °C and 15 °C in case of BO-2, BO-3, respectively. In terms of viscosity index, P1 shows the better results at 6000 ppm concentration by increasing the VI by 13.9% compared to P2 and P3, which is a maximum increase in VI among different base oils used for study. Increasing the concentration of polymeric additives in base oils reduces the corrosion as per the standard corrosion test method ASTM D130-12. Synthesis of the copolymeric additives composed of alkyl acrylates and LCAO under solvent-free conditions by the free radical polymerization, which shows a potential eco-friendly additive for base oils, was demonstrated. The alkyl acrylate and LCAO appendage on polymeric additive enabled better miscibility and transparency with base oils and without modifying the nature of base oils. Polymeric additive blended base oils show superior properties in terms of increasing the viscosity index, depressing the pour point and anticorrosion. This has the potential of exploration in pour point depressants in petroleum industry. [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]

The paper presents the results of research into the biostability of M-10 base oil samples with addition of protective additives for various purposes which are a part of the earlier composition of M-14В2 lubricating oil developed by us. It was established that despite the different nature of these additives (alkyl phenolates, dithiophosphates, sulfonates), all these samples are affected by microorganisms. It found that the introduction of 0,25% α-phenyl-β-nitroethene into the composition of these samples provides their long-term protection from microbiological damage. Based on the results obtained, a new biostable lubricating oil composition for marine, locomotive and stationary diesel engines was developed which does not lose its performance properties for a long time. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to propose a new strategy to functionalize zeolitic imidazolate frameworks (ZIF-8) to improve its dispersion stability and tribological properties in lubricating oil. Design/methodology/approach: Dialkyl dithiophosphate polydopamine ZIF-8 (DDP@PDA@ZIF-8) was prepared via mussel-inspired chemistry and the Michael addition reaction. The tribological properties of DDP@PDA@ZIF-8 as an additive in the white oil were evaluated with four-ball friction and wear tester at different temperatures. The worn surface was analyzed using X-ray photoelectron spectrum (XPS). Findings: The as-prepared DDP@PDA@ZIF-8 shows high dispersion stability in the white oil. Tribological results confirmed that the DDP@PDA@ZIF-8 exhibited a small wear scar diameter at 25°C. However, excellent friction reduction and anti-wear properties were observed at 75°C. The XPS result indicates that a series of tribochemical reactions occurred on the worn surface, forming the complex protective film. Originality/value: This paper provides a study of highly dispersed ZIF-8 as lubrication additives. [ABSTRACT FROM AUTHOR]

One of the major applications of zinc dialkyldithiophosphates (ZnDDPs) is their usage as an anti-wear additive in lubricants including greases, hydraulic oils, and motor oils. ZnDDPs also could be used as corrosion inhibitors and antioxidants. In this study, GC/MS with solid-phase extraction (SPE) pretreatment was used to effectively remove base oils in lubricants and qualitative and quantitative analysis method for ZnDDPs in automotive lubricants. As a pretreatment method, liquid–liquid extraction (LLE) and SPE were applied. The SPE method using mixed absorbent containing 1.0% of active carbon in silica gel base showed the best results in both recovery and reproducibility. The LOD and LOQ of the developed method were 2.2 µg/ml and 6.7 µg/ml, respectively. And this method showed very good reproducibility of less than 0.1% RSD for the standard sample analysis. The developed method was successively applied to qualitative and quantitative analyses of ZnDDP in various real automotive lubricant samples. [ABSTRACT FROM AUTHOR]

Nano-lubricants offer improved tribological properties in many applications, such as machines and engines. The presence of nanoparticles in the lubricating oil affects its wear, friction, thermal, chemical and physical properties in many ways. Titanium dioxide (TiO2) is a promising lubricant additive for enhanced engine efficiency. This article reports the effect of 10 W-30 pure base engine oil suspended TiO2 nanoparticles. Four different volume concentrations (0.01%, 0.025%, 0.050% and 0.075%) of TiO2 nanoparticles in the base lubricating oil are used for the analysis. The tribological tests were performed at ambient temperature as well as at 75 °C using a four ball tribometer. Scanning electron microscope (SEM) and Alicona Inginite Focus G5 microscope were used to analyze the worn surface. The results show that the surface-modified TiO2 nanoparticles can remarkably improve the load-carrying capacity, the friction reducing, and anti-wear abilities of the additive oil. The diameter of the wear trace and the coefficient of friction are the tribological properties analyzed for the nano-lubricant prepared at different volume concentration (VC). It was found that the diameter of the wear scar and the coefficient of friction increase with increasing VC of TiO2 nanoparticles in the lubricating oil. The main objective of the paper is to present the recent progress and, consequently, to develop a comprehensive understanding of the tribological behavior of engine oil mixed with TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

In this study, the rheological behavior and tribological properties of a nano-lubricant containing SiO2 nanoparticles in SAE40 engine oil are experimentally investigated. Nano-lubricant has been prepared with two-step method using an ultrasonic homogenizer. The rheological behavior of nano-lubricant checked out in all studied temperatures (ranging from 15˚C to 65˚C) and different solid volume fractions (ranging from 0 to 1%) and it shows non-Newtonian behavior (pseudoplastic). Also, an accurate correlation is presented for the prediction of nano-lubricant's viscosity based on experimental data. A pin-on-disk tribometer was performed to investigate the tribological behavior of nano-lubricant. Results revealed that in φ = 0.1%, the wear rate and friction coefficient have been decreased by 50% and 18.46%, respectively, compared with the base oil. In addition, the nano-lubricant with optimum concentration and base oil was tested in the operational condition of diesel engines at the same condition and the abrasive elements of these engine oils were analyzed. Other important factors including pour point and flash point were also determined which showed that the addition of SiO2 nanoparticles to the base oil in φ = 0.1% will cause a 3.8% improvement in flash point compared with the base oil. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to prevent the sharp decline in the load-carrying capacity of lubricating oil film under harsh conditions of abrupt changes in friction interface temperature, which is a major challenge in lubrication technology. Design/methodology/approach: In this paper, we synthesized a series of silver pyrazole methylpyridine complexes containing a high metal concentration and minimal supporting organic ligands (complex 1 [Ag(LMe)]2(BF4)2, complex 2 [Ag(Li-Pr)n](BF4)n and complex 3 [Ag(LMe)(NO3)]2). The thermal decompose behavior of as-prepared silver complex was investigated by thermogravimetric analysis and X-ray photoelectron spectrometry (XPS). Four-ball friction testers were used to evaluate the friction and wear properties of lubricating oil in the temperature ranges associated with the operation of modern heavy machinery. Findings: The complex decomposed silver particles at high-temperature, which could fill the pits on the friction surface, change the wear form of the friction pair and reduce the roughness of the friction surface. Reduction in both friction coefficients and wear scar diameters was obtained by adding silver complexes in oil. The lubricating oil, with the additive content of 1.5 Wt.%, has the best tribological performance, moreover, the lubricating performance of the silver complexes in oil were correlated with their concentration and thermal decomposed temperatures, respectively. Originality/value: As a result, a series of silver pyrazole methylpyridine complexes as oil additives can support friction and wear reduction under abrupt high-temperature conditions are intended to be a controllable backup lubricant additive. [ABSTRACT FROM AUTHOR]

As a nanoscale carbon material, carbon spheres (CS) are expected to achieve ideal lubrication performance by reducing direct contact between friction pairs and bearing loads. In this work, 2D Cu-MOFs surface modified (CS@Cu(BDC)) CS was added to the base oil, which exhibited a remarkable reduction in friction coefficient and wear rate (62.2%, 33.9%), the width of the friction pair wear marks was decreased by 30.8% relative to the base oil. The improvement in performance can be attributed to the polishing, repairing, filling and tribo-film forming effects of CS@Cu(BDC). This work provided an effective strategy for diversifying the surface structure of CS and opened new avenues for the development of a new generation of green and efficient lubricant additives. • Introducing 2D Cu-MOFs on the surface of carbon spheres as a nanoadditive for heavy-duty lubricants. • Composite nanoparticles present excellent dispersion stability in the base oil. • Form a stable tribofilm on the surface of the Fe substrate. • The synergistic effect of carbon spheres and MOFs shows significant anti-wear properties. [ABSTRACT FROM AUTHOR]

The interlayer coupling interaction of bentonite (BT) material behave superior performance and unique functionality by introducing guest functional molecules. As intercalation agents, ionic liquids (ILs) with high polarity and molecular structure regulation can provide excellent lubricity and multifunctionality. Herein, the novel IL-modified intercalation bentonite (IL-BT) were designed and prepared by functionalization of the imidazolium-based and phosphorus-based ILs. And ultra-thin lamellar structure morphology is obtained, which contributes to the enhanced dispersion and stability in base oils. For IL -BT, their strong interlayer slip can significantly improve lubrication properties. Besides, FIB-TEM results show that unique tribofilm is detected at the sliding asperity. The excellent tribological properties are attributed to the synergistic lubricity of interlayer slip, tribo-chemical reaction and repair effect during friction. [Display omitted] • Novel IL functionalized bentonite composite (IL-BT) was designed and prepared. • Ultra-thin lamellar morphology for IL-BT was obtained, as well as excellent dispersion stability. • Superior tribological properties can be noticed even at 2.74 GPa. • The synergistic lubricity and unique triboflim induced by IL-BT is explored on the metal surface. [ABSTRACT FROM AUTHOR]

In deep drilling, lubrication and cooling tremendously affect drill life and machining quality. In this work, we investigate on the cryogenic Minimum Quantity Lubrication (cMQL) with oil and liquid or supercritical CO 2. In the drilling process, both fluids are conducted through small flow channels inside the drill to the cutting edge. For a stable process, single-phase conditions are required. Systems of five different lubricants with carbon dioxide are investigated at 25 °C, 40 °C and 60 °C. Investigations are made optically in a view cell at pressures between 60 bar and 300 bar and quantitatively between 60 bar and 250 bar using the static-analytical method. For the application, information on the mixing kinetics of the oils and CO 2 is further required. To get an insight into the flow behavior under pressure, an optically accessible flow duct is presented that resembles the conditions in the real drilling process. [Display omitted] • Observation of phase behavior of ester base oils for MQL up to 300 bar. • Measurement of isotherms of mutual solubility of lubricant and CO 2 up to 250 bar. • Design of a transparent high-pressure flow cell for pressure up to 100 bar. • Observation of two-phase and single-phase flow behavior under variable conditions. • Evaluation of flow behavior and solubility with respect to drilling application. [ABSTRACT FROM AUTHOR]

Viscosity modifiers are inherent to many lubricating multigrade oils as they reduce the temperature dependence on the viscosity of the oil, thus increasing the viscosity index. However, direct evidence of physical mechanisms to which viscosity modifiers increase viscosity index is still lacking due to the lack of appropriate analysis tools. Here, we report a method using dynamic light scattering (DLS) to study the solution behavior and coil size change of ethylene-propylene copolymers as well as polyoctadecylmethacrylate at 1.0 wt. % in a polyalphaolefin oil. The usefulness and limitations of the DLS for monitoring polymer coil size and dynamic solution behavior in oil are discussed. [ABSTRACT FROM AUTHOR]

This paper discusses the potential of using palm-castor oil blends as lubricating oil in industrial applications. Laboratory experiments to measure kinematic viscosity, flash point, copper corrosion, demulsibility, pour point and total acid number were conducted and compared with commercial lubricating oils. Change in kinematic viscosity with temperature of different palm-castor blends were best fitted to the Arrhenius model with R2 value higher than 0.95 and AARD% is less than 1.5%. Addition of 40 and 50% of castor oil to 60 and 40% of palm oil resulted solutions with similar properties of Hydraulic68 and SAE30, respectively. [ABSTRACT FROM AUTHOR]

Cutting fluid has cooling and lubricating properties and is an important part of the field of metal machining. Owing to harmful additives, base oils with poor biodegradability, defects in processing methods, and unreasonable emissions of waste cutting fluids, cutting fluids have serious pollution problems, which pose challenges to global carbon emissions laws and regulations. However, the current research on cutting fluid and its circulating purification technique lacks systematic review papers to provide scientific technical guidance for actual production. In this study, the key scientific issues in the research achievements of eco-friendly cutting fluid and waste fluid treatment are clarified. First, the preparation and mechanism of organic additives are summarized, and the influence of the physical and chemical properties of vegetable base oils on lubricating properties is analyzed. Then, the process characteristics of cutting fluid reduction supply methods are systematically evaluated. Second, the treatment of oil mist and miscellaneous oil, the removal mechanism and approach of microorganisms, and the design principles of integrated recycling equipment are outlined. The conclusion is concluded that the synergistic effect of organic additives, biodegradable vegetable base oils and recycling purification effectively reduces the environmental pollution of cutting fluids. Finally, in view of the limitations of the cutting fluid and its circulating purification technique, the prospects of amino acid additive development, self-adapting jet parameter supply system, matching mechanism between processing conditions and cutting fluid are put forward, which provides the basis and support for the engineering application and development of cutting fluid and its circulating purification. [ABSTRACT FROM AUTHOR]

In this work, WS2 microspheres were synthesized through a facile hydrothermal route. The as-synthesized samples were characterized by powder X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive spectroscopy and scanning electron microscopy (SEM). The XRD spectrum of the sample is indexed to hexagonal WS2. SEM graphics of the products reveal that the WS2 microspheres with diameters of about 2-8 µm were synthesized. The tribological properties of WS2 microspheres as oil additives were tested on a ball-disk tribometer. Under the given experimental conditions, the friction coefficient of the oil containing WS2 is lower than that of the base oil. The formation of rolling friction between the friction pairs and the smooth friction film on the wear surface are considered to be the reason for the good lubricating effect of WS2 microspheres as an additive. [ABSTRACT FROM AUTHOR]

A correction to the article "The Thin-Layer Microchromatography (ITLC) and TLC--FID Technique as a New Methodology in the Study of Lubricating Oils" in a 2017 issue is presented.

Oils and grease have beneficial effects on moving parts such as connecting rod, gears, shafts, and engine to reduce wear and friction. The properties of lubricants such as tribological and rheological properties are an important role in oils and grease characterization. Nano additives on lubricant oils play an important role in anti-wear; reduce the coefficient of friction and enhance the rheological properties. The Tribological and rheological behavior of base oil 15W50 which have different concentrations of multi-wall Carbon Nanotubes (MWCNTs) (0.5, 1, 1.5, and 2 wt%), and constant amount of graphene nanosheets (GNSs) (0.5 wt%) were investigated. This research is the first one in studying the effect of hybrid nano additives of (MWCNTs) and (GNs) on the tribological and rheological properties of lubricant oils. Tribological characterization was carried out on four ball testing model under different loads (200, 400, 600, and 800 N). The kinematic viscosity, flash point, pour point, and thermal conductivity of nanofluid added 15W50 lubricant are estimated and compared with base oil. The results showed that nano additives improve the wear scar and coefficient of friction by 78% and 48%, respectively. The flash point, thermal conductivity, kinematic viscosity, and pour point, were improved by 15%, 77%, 76.8%, and 20%, respectively compared with the base oil. The hybrid addition of CNTs/GNs nanoparticles enhanced the properties of 15W50 engine oil. [ABSTRACT FROM AUTHOR]

In this study, we used a four-ball friction and wear testing machine to test the tribological properties of [HPy]BF4 ionic liquids (ILs), low-layer graphene (G), and IL and G compounds (IL/G) as lubricant additives at variousconcentrations, loads, and speeds. The morphology of the wear scar was characterized by a white-light interferometer and a scanning electron microscope (SEM). The results showed that the optimal concentrations of IL and G were 0.10 wt.% and 0.05 wt.%, respectively. When the IL concentration was 0.10 wt.%, the friction coefficient and the wear scar diameter (WSD) reduced by approximately 18% and 8%, respectively, compared to the base oil. When the concentration of G was 0.05 wt.%, the friction coefficient and WSD reduced by approximately 23% and 12%, respectively, compared to the base oil. After adding the optimal concentration of the IL/G composite additive under the same test conditions, the average friction coefficient of the steel ball reduced by approximately 30%, and the average WSD reduced by approximately 18%. IL/G nanoadditives could be easily attached to the pit area on the friction surface of the steel ball, which made the contact surface of the friction pair smoother and the area of the oil film bearing the load larger, compared to those using the base oil. These two combined phenomena promoted synergistic antifriction and antiwear effects, which significantly improved the frictional performance of the base oil. During the friction process, the graphene in the G/IL composite material slowly becomes flat from wrinkles, so that the graphene exists in the lubricating sample in an ordered state. The reason why the graphene in the G/IL composite material can be stably adsorbed on the friction interface is due to the π–π interaction between the ionic liquid and the graphene. The ionic liquid pins the graphene on the friction interface to suppress the friction of the graphene. The wrinkle effect in the process significantly improves the stability of the graphene adsorption film and the friction reduction effect of graphene. [ABSTRACT FROM AUTHOR]

Lubricants can significantly improve the anti-wear performance and prolong the service life of machines. It has been found that the introduction of additives can further enhance the performance of lubricating oil and meet harsh working conditions, such as high temperature, high speed, and high load. In this study, 1% by weight of CuO, WC, and WS2 nanoparticles were added to Polyalphaolefins (PAO) base oil to evaluate tribological response. The study focused on using different surfactants including Oleic acid (OA) and Polyisobutylene succinimides (PIBS), to determine their impact of agglomeration and the observed tribological response in the boundary lubrication regime. The results showed that adding 10% OA while sonicating the particles for 30 min reduced the agglomeration the most, and adding 1% OA while sonicating for 120 min produced a more uniform dispersion of the nanoparticles used in this study. Friction studies showed that the nanoparticles additives do not appreciably impact the friction compared to base oil. Wear resistance was improved by about 60% for CuO and WC with 1% OA and sonicated for 120 min. The study suggests that conditions that minimize agglomeration and promote high dispersion lead to favorable wear resistance under boundary lubricant conditions. [ABSTRACT FROM AUTHOR]

Advances in lubricants are vital to the pursuit of energy efficiency and sustainable development. It is well known that the essence of lubricating oil is lubricant additives, especially the friction-reducing and anti-wear additives. Carbon quantum dots (CQDs), a novel zero-dimensional carbon-based nanomaterial, have attained growing expectations in material and chemical sciences because of their extraordinary properties such as low toxicity and environmentally friendly, high chemical and thermal stability, and good designability. Since their discovery, CQDs have shown great potential in many applications including sensors, medicine, photovoltaic devices, biology, and tribology. The latest application of CQDs as the high-performance friction-reducing and anti-wear additives has garnered increasing attention. With the in-depth study, CQDs have gradually exhibited their excellent tribological properties, especially acted as additives in lubricating base oils. This paper has reviewed the progress in the research and development of CQDs-based lubricant additives by introducing lots of successful applications of CQDs-based additives in the present work and then highlighted the friction-reducing and anti-wear property, superiority, as well as the lubrication mechanism of CQDs as an additive, along with some discussion on challenges and perspectives in this significant and promising field. Finally, we offered a series of suggestions for developing the next-generation high-performance CQDs-based lubricant additives. This work presented the carbon quantum dots as the lubricant additives of lubricating base oils. [ABSTRACT FROM AUTHOR]

Tribological behavior of Si 3 N 4 ceramic/GCr15 steel components under lubrication of graphene was investigated and found that friction reduction and wear resistance of the sliding pairs were improved by 27% and 43%, respectively, after adding 0.075 wt% of graphene into the base oil. Herein, the lubrication mechanism of graphene nanoplates as oil additives was focused on to promote the practical application of graphene in hybrid ceramic bearings industry. In order to investigate the effect of oil film thickness on tribological properties, the viscosity of blended lubricating oil containing different concentration of graphene was measured and the oil film thickness between rubbing surfaces was calculated using a full numerical solution in point contacts. In addition, the rubbing surfaces were analyzed with combination of EDS and Raman technique. The results demonstrated that the viscosity of base oil and oil film thickness increased with addition of graphene. Graphene entered rubbing interface and prevented ceramic/steel pairs from mechanical contact. Lubrication mechanism including interlayer shearing, surface mending and protective film formation contributed to reduce the friction coefficient and worn scar diameter. [ABSTRACT FROM AUTHOR]

There is a large amount of information about the wear failure status in the particles, and the current wear failure status can be judged by monitoring them. In this paper, the main shaft bearing wear failure causes the change of metal particles in the lubricating oil and further causes the deterioration of the bearing condition. Based on the lubricating oil metal chip particle test system on the bearing testing machine, the particle size distribution change data in the bearing oil is obtained and the metal oil The main bearing fault prediction model with particle number and particle size as characteristic parameters realizes the fault diagnosis and condition evaluation of main shaft bearing wear based on the lubricating oil metal chip particle test, thereby effectively providing technical support for turboshaft engine fault diagnosis. [ABSTRACT FROM AUTHOR]

The review analyzes the published data on scientific, applied, and marketing studies on the development of modern synthetic bases of motor oils as marketable products. The conventional world-accepted classifications and performance characteristics of base oils are considered. The main trends in scientific research on the development of effective synthetic bases of motor oils and prospects for their further development are presented. The assessment of the state of the global and Russian motor oil markets according to major market indicators is given; the market development forecast for the coming years is presented. [ABSTRACT FROM AUTHOR]