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As the inner working surface of a diesel engine, the cylinder liner is subjected to a harsh frictional wear environment, which can lead to performance degradation and ultimately affect the engine's service life. Ceramic coatings can improve the wear resistance of the cylinder liner, thereby enhancing the reliability and stability of the diesel engine. In this study, Cr 2 O 3 –Y 2 O 3 ceramic composite coatings were deposited on the substrate of 304 stainless steel by atmospheric plasma spraying (APS). The influence of Y 2 O 3 content on the microstructure, porosity, phase composition, microhardness and wear performance of the composite coating was investigated. The results showed that the composite coatings exhibited a typical layered structure, and Y 2 O 3 and Cr 2 O 3 were dispersed relatively evenly. When the Y 2 O 3 content was 10 %, the coating had the lowest porosity rate of 5.41 % and the highest hardness of 1094.6 HV 1. As the Y 2 O 3 content increased, the coating exhibited an increase in porosity and a decrease in hardness. Under dry friction conditions, the friction coefficient curve underwent a rapid increase phase, followed by stabilizing within the range of 0.29–0.40. When the Y 2 O 3 content is 10 %, the coating exhibits the best wear resistance, including the lowest coefficient of friction, wear rate, and scratch depth. However, the composite exhibits the worst wear resistance when the Y 2 O 3 content reaches 50 %. The wear mechanism was altered by the addition of Y 2 O 3. At lower Y 2 O 3 content, the predominant wear mechanism was abrasive wear resulting from particle refinement. Conversely, at higher content, adhesive wear caused by wear transfer from the milling balls became more prominent. [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]

This article proposes using the Arrhenius model for estimating the viscosity of a mixture of two liquids in the quantitative assessment of the physicochemical properties of lubricating oils in the context of assessing the level of dilution of lubricating oil with diesel oil. Dynamic are made of mixtures of lubricating oil and diesel oil with known concentrations of 0, 1, 2, 5, 10, 20, 50, and 100% m/m of the diesel oil content in the mixture. Mixtures of the most popular oils (viscosity classes SAE 30 and SAE 40) with diesel oil that meet the requirements of the DMX of the marine distillate fuels category are prepared and tested. Viscosity measurements are performed at 40, 50, 60, 70, 80, 90, and 100 °C temperatures. The Arrhenius model is used to estimate the viscosity of the mixtures with an assumed diesel oil content and to estimate the diesel oil concentration in the mixtures with a known measured viscosity value. In both cases, the absolute estimation error is determined, and the accuracy of the estimation is assessed against the known concentration of diesel oil in the mixture with lubricating oil and the temperature at which the viscosity is measured. The estimated concentrations of diesel oil in mixtures with lubricating oil are useful to assess the condition of the lubricating oil (for concentrations of diesel oil lower than 5% m/m). The method is proposed to be used in practice to support standard laboratory oil analysis. [ABSTRACT FROM AUTHOR]

The current study is basically focused on investigating the possible ways to enhance the lubricating oil film performance and hence ship energy efficiency of marine journal bearings in general terms. For the intended purpose, a novel numerical Circumferential Grooved Bearing (CGB) model was developed to assess journal bearing operating conditions based on versatile simulation analyses. Prior to all conducted test trials, the model validation has been confirmed based on the conformity between numerical outcomes and those derived from experimental procedures depending on Universal Journal Bearing Test Rig. CGB performance was evaluated at slow speed variations from 25 rpm up to 125 rpm and different applied loads utilizing the two lubricant oil grades of 5W40 and 0W30. Reducing shaft rotational speed by 80% was found to incur a reduction in the maximum oil film pressure value by 1.17 bar and 0.97 bar for the two aforementioned lubricants respectively. Further, the increase of applied loads from 1079 N up to 1471 N at a constant speed of 75 rpm reduces the maximum oil film pressure ratio by 0.14 and 0.18 for the two oil grades subsequently. [ABSTRACT FROM AUTHOR]

Oil‐containing nanocapsules are prepared and used to solve the challenges arising from the low mechanical properties and high coefficient of friction (CoF) of epoxy resin (EP). The shell of the nanocapsules is amorphous carbon and the core is lubricating oil (ATF6, Automatic Transmission Fluid 6). The nanocapsules are uniform hollow spheres with an average particle diameter of 530 nm and a shell thickness of 60 nm. The mass content of the lubricating oil encapsulated in the nanocapsules can reach 64.88% upon vacuum impregnation. Enhancing with the oil‐containing nanocapsules, the tribological properties of EP composites are studied in detail. Compared with those of neat EP, the compressive strength of the EP composite with 7 vol% nanocapsules improves by 9.2%, and the CoF and wear rate reduce by 71.70% and 89.38%, respectively. During the friction process, the oil‐containing nanocapsules are crushed and the oil is released, which contributes to the antifriction property of EP composites. Moreover, the results are expected to open up new ideas for the research and development of self‐lubricating materials. [ABSTRACT FROM AUTHOR]

In this work, the influence of polytetrafluoroethylene (PTFE) filler size and testing conditions (i.e., air, water, and lubricating oil) on the tribological properties of poly(arylene ether nitrile) (PEN) was systematically investigated. The results showed that the addition of PTFE was beneficial to improve the tribological properties of PEN‐based composites which was related to the easier formation of transfer film on the surface of friction pair. Samples which were tested in water demonstrated a relatively higher friction coefficient (μ) and wear loss when compared with those tested in dry air and lubricating oil scenarios, which was attributed to the fact that friction induced heat and wear debris could be timely removed by water. In addition, the infiltration of water further reduced the interaction between PTFE filler and PEN, which aggravated the wear loss of sample blocks. When tested in lubricating oil, pure PEN showed the lowest wear loss when compared with that of PEN/PTFE composites. At a given content (20 wt%) of PTFE fillers, PEN/PTFE1.5μm exhibited the lowest μ in lubricating oil whereas PEN/PTFE5μm demonstrated the lowest specific wear loss in air condition (1.18 × 10−6 mm3/N·m). This work provided some useful information for the design and application of PTFE‐containing polymer composites that can be targeted in different lubrication scenarios in industrial fields. [ABSTRACT FROM AUTHOR]

The need to cope with carbon dioxide abatement has prompted the development of innovative technologies for sustainable mobility. Meanwhile, these technologies consolidate, an important role will be played by internal combustion engines fed with non-fossil fuels such as hydrogen. Theoretically, the combustion of hydrogen should not produce carbon-based emissions. Nevertheless, particles can be found in the exhaust of hydrogen-fueled engines because of the lubricating oil. In this study, a thorough examination of the impact of the engine lubricant on the mechanisms leading to the formation of the particles and the high levels of hazardous pollutants was performed in this study. Experiments were carried out on a direct injection spark ignition engine fueled with hydrogen. The analysis was conducted at 2000 and 3000 rpm both low and full load. Number and size particle distribution were determined by means of on-line measurement on the diluted exhaust. Off-line chemical characterization through analytic techniques was realized on the condensed exhaust and on the particles collected on a filter. Experimental results pointed out that the extent of the particle size varies according to the engine speed and load, evidencing the different role of the oil ascribable to the environmental conditions. It was found that aromatic molecules and nanoparticles are present in the exhausts at all the investigated operating conditions, whereas soot aggregates are formed only at high engine speed. • Physical and chemical characterization of particles emitted by a SI engine fueled with hydrogen. • Role of lubricating oil on the mechanisms of particle formation for hydrogen fueling. • Impact of the operating condition, engine speed and load, on the particles emitted by a hydrogen-fueled SI engine. • Presence of PAH, alkyl-PAHs, oxy-PAHs and nanoparticles in the exhausts. • Soot formation at higher engine speed. [ABSTRACT FROM AUTHOR]

Xanthoceras sorbifolium Bunge oil exhibits favorable characteristics such as excellent low temperature fluidity, high flash point, and degradability. However, it also suffers from drawbacks including low kinematic viscosity at low temperatures and significant loss of kinematic viscosity at high temperatures. In view of these characteristics of X. sorbifolium oil, it was modified in this work with a combination of ethyl cellulose (EC), montmorillonite (MMT), and cetyltrimethylammonium chloride (CTAB). The effects of temperature, time, and additive content on the rheological properties of lubricating oil were studied. The kinematic viscosity of the prepared lubricating oil reached up to 433 mm2/s at 40 °C and 51.1 mm2/s at 100 °C. The coagulation point could be reduced to -25 °C, the friction coefficient was 0.026, and the average wear spot diameter was 0.81 mm, The anti-friction performance was enhanced, and the anti-wear performance decreased somewhat. The prepared lubricating oil had the characteristics of high kinematic viscosity at high temperature and excellent rheological properties at low temperature. It also met the energy and environmental application requirements of a green, environmentally friendly, and biodegradable sustainable development strategy. This study greatly broadens the application range of lubricating oil. [ABSTRACT FROM AUTHOR]

When exposed to high surface temperatures, engine lubricating oils degrade and may form solid deposits, which cause operational issues and increase shutdown time and maintenance costs. Despite its being a common issue in engine operation, the information available on the mechanics of this phenomenon is still lacking, and the experimental data and conditions must be updated to match the improvements in both lubricant stability and engine efficiency. To this end, an experimental apparatus has been developed to study the mechanisms that lead to the degradation and deposit formation of lubricants at high temperatures. The apparatus is designed to operate at pressures up to 69 bar, surface temperatures up to 650 °C, oil bulk temperatures up to 550 °C, and flow rates of <14 mL/min. In this apparatus, the oil is cycled through a heated test section, and deposits accumulate on the heated surface. The time required for deposits to start accumulating under the test conditions is determined based on the recorded temperature traces, and collected oil and deposit samples may be analyzed to determine changes in composition over time due to high-temperature exposure. The removable test section can be modified to accommodate different geometries, surface materials, and flow paths to adapt the instrument to a range of potential research directions. This paper presents the technical details of the new apparatus and the steps taken to characterize the experimental conditions. In addition, sample data are provided to show the unique capabilities of the new instrument, and an Arrhenius plot for Castrol Perfecto X 32 in the surface temperature range of 445–475 °C is presented as a demonstration of its use for quantifying the coking delay time. The new instrument detailed herein is the first such device to demonstrate a reliable, lab-scale technique for studying lube oil coke formation and deposition at temperatures and pressures of interest to power generation gas turbines. [ABSTRACT FROM AUTHOR]

Hydraulic systems are widely used in different industries, such as civil construction, aerospace, automotive, oil, among others. The hydraulic fluid or lubricating oil of these systems is an important source of information regarding the state of the machines. In this way, the analysis of lubricating oil proves to be an important and effective tool to monitor the condition of components of hydraulic systems. Since the emergence of predictive maintenance, researchers have been dedicated to developing methods of online monitoring of hydraulic fluids in order to prevent failures, increase safety and reduce maintenance costs. Therefore, the present work sought to carry out a discussion on the importance of monitoring the hydraulic fluid, bringing the main methods of analysis and the most recent advances. [ABSTRACT FROM AUTHOR]

Microscopic analyses of the effects of ash on particulate matter oxidation are rather scarce. In this study, three different lubricating oils with varying ash contents were used to investigate their effects on the nanostructure of diesel particulate matter. The nanostructure and nanostructure parameters, including fringe length, fringe separation distance, and fringe tortuosity, were studied using high-resolution transmission electron microscopy. The results show that all samples obtained from blending with different lubricant oil present typical core–shell structures. The inner cores remain relatively unchanged, whereas the thickness of the outer shells increases with the increasing ash content in the lubricant oil under the same working conditions. The fringe length increases and the fringe separation distance decreases with the rising ash content in the lubricant oil operating in the same working conditions. The fringe tortuosity decreases when the ash content in the lubricant oil increases from 0.92% to 1.21%, but shows little change when the ash content in the lubricant oil increases from 1.21% to 1.92%. Based on the effects of ash on the nanostructure parameters, it can be inferred that the oxidation activity of particles decreases with increasing ash content in the lubricant oil. [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]

Lubricants are of paramount importance in protecting metallic contact surfaces and reducing friction. The viscosity of lubricating oil can be engineered by introducing long linear polymers, such as poly(lauryl methacrylate) (PLMA). In particular, the formation of adsorption films by using polymers with hydroxy or amino side groups has attracted much attention in recent years. In this study, copolymers with controlled structure were synthesised by SARA ATRP, which can be used in large scale production. A comparison of friction and wear under boundary lubrication was conducted using both statistical and block copolymers with low Ð. Friction test results using a reciprocating sliding machine (SRV) showed that the block copolymers were less likely to desorb from the metal surface than the statistical copolymers. In addition, the wear evaluation after the SRV test showed that the block copolymer had less wear and less wear debris. [ABSTRACT FROM AUTHOR]

It is well known that lubricating oils reduce the friction coefficient between two surfaces in contact. Since petroleum lubricants are toxic and have a low biodegradability, they are typically not appropriate for the environment. As a result, as public worries about a pollution-free environment grow, so does the demand for lubricants that are acceptable to the environment. The primary rationale for utilizing vegetable oils in forthcoming bio-lubricant formulations is their high lubricating performance, low toxicity, sustainable, and biodegradability. Plant oils hold great potential as a foundational fluid for bio-lubricants, since their synthetic and vegetable oil-based esters provide the most environmentally friendly option for creating lubricants. In this study, Jatropha and Jojoba raw oil were chemically modified via epoxidation followed by transesterification to produce bio-lubricants. Thus, the aim of this work is to develop a bio-lubricant from jatropha and jojoba methyl ester, further adding nanoparticles multiwalled nanotubes and titanium dioxide for improvement of tribological properties. The chemical modification of the jatropha and jojoba oil results in a decrease in iodine value, resulting in the breaking of carbon bonds. Viscosity tests were performed using the Anton Par MCR 92 Rheometer, with temperature ranging from 30°C to 80°C. Thermal stability measurements of bio-lubricants were performed using PerkinElmer’s Thermogravimetric analyzer-4000 instrument and thermal degradation temperature for Epoxidized Jatropha-sulfuric acid, Epoxidized Jatropha-hydrochloric acid, Epoxidized Jojoba-sulfuric acid and Epoxidized Jojoba-Hydrochloric acid samples are 238°C, 224°C, 230°C, and 244°C, respectively. The 94.68% and 79.85% reduction in wear was obtained for Epoxidized Jojoba with hydrochloric acid, titanium dioxide and epoxidized Jatropha with sulfuric acid, multiwalled carbon nanotubes in comparison with their epoxidized samples. The coefficient of friction of Epoxidized Jatropha with sulfuric acid, multiwalled carbon nanotubes and Epoxidized Jojoba with Hydrochloric acid, Titanium dioxide sample was found to be 0.061 and 0.059, respectively [ABSTRACT FROM AUTHOR]

Three kinds of 1,8-diazabicyclic [5.4.0] undecane-7-ene(DBU) derivatives fatty acid-based long-chain ionic liquids were designed and synthesized, the oil solubility, corrosion and anti-wear and antifriction properties of ionic liquids were investigated, the feasibility of these ionic liquids as lubricating oil additives was discussed. The results showed that the fatty acid ionic liquids derived from DBU had good oil solubility and no corrosion to copper sheet, at the same time, the anti-wear and anti-friction property of the oil can be improved. It provides a reference for the research and development of high quality additives. [ABSTRACT FROM AUTHOR]

Oil-air flow within an oil bath lubrication tapered roller bearing is essential for the lubrication and cooling of the bearing. In this paper, we develop a simulation model to investigate the flow field of tapered roller bearings with oil bath lubrication. The multiple reference frame (MRF) approach is used to describe the physical motion of the bearing, and the volume of fluid (VOF) two-phase flow model is used to track the oil-air interface in the flow field. The effects of mesh scale, geometric gap, and oil reservoir size on calculation time and convergence accuracy are examined in detail, and the effects of inner ring rotational speed and lubricant viscosity on frictional torque are systematically studied. The results of the numerical simulation indicate that as the gap distance between the raceway and the rolling elements decreases, the frictional torque is mainly generated by churning losses at the inner raceway and the rolling elements. The frictional torque increases with increasing inner ring speed and lubricating oil viscosity, with the rolling element contributing the largest portion at approximately 50% of the total. We demonstrate the effectiveness of a method to reduce frictional torque by optimizing the internal structure of the bearing to control oil flow. By optimizing the cage structure and reducing the roller halfcone angle, frictional torque can be reduced by 29.1% and 26.2%, respectively. [ABSTRACT FROM AUTHOR]

Accidental crankcase explosions in marine diesel engines are presumably caused by the inflammation of lubricating oil in air followed by flame propagation and pressure buildup. This manuscript deals with the numerical simulation of internal unvented and vented crankcase explosions of lubricating oil mist using the 3D CFD approach for two-phase turbulent reactive flow with finite-rate turbulent/molecular mixing and chemistry. The lubricating oil mist was treated as either monodispersed with a droplet size of 60 μm or polydispersed with a trimodal droplet size distribution (10 μ m (10 wt%), 250 μ m (10 wt%), and 500 μ m (80 wt%)). The mist was partly pre-evaporated with pre-evaporation degrees of 60%, 70%, and 80%. As an example, a typical low-speed two-stroke six-cylinder marine diesel engine was considered. Four possible accidental ignition sites were considered in different linked segments of the crankcase, namely the leakage of hot blow-by gases through the faulty stuffing box, a hot spot on the crankpin bearing, electrostatic discharge in the open space at the A-frame, and a hot spot on the main bearing. Calculations show that the most important parameter affecting the dynamics of crankcase explosion is the pre-evaporation degree of the oil mist, whereas the oil droplet size distribution plays a minor role. The most severe unvented explosion was caused by the hot spot ignition of the oil mist on the main bearing and flame breaking through the windows connecting the crankcase segments. The predicted maximum rate of pressure rise in the crankcase attained 0.6–0.7 bar/s, whereas the apparent turbulent burning velocity attained 7–8 m/s. The rate of heat release attained a value of 13 MW. Explosion venting caused the rate of pressure rise to decrease and become negative. However, vent opening does not lead to an immediate pressure drop in the crankcase: the pressure keeps growing for a certain time and attains a maximum value that can be a factor of 2 higher than the vent opening pressure. [ABSTRACT FROM AUTHOR]

The rheology of a conventional lithium-12 hydroxystearate bearing grease changes significantly when it is subjected to mechanical shear. Often this shear energy–along with the consequent entropy–is measured and used in engineering and thermodynamic models, leading to grease life models for predicting bearing seizure due to insufficiently thick film or loss of lubricity of the base oil/grease. In this degradation process, the bonds between the individual molecules, consisting mainly of the fairly weak van der Waals bonds and/or hydrogen bonds, are broken during this shearing process. In this article, we show that only a very small portion of the shear energy is needed to break these bonds and that the vast majority is dissipated as heat due to the lubricant viscosity, also known as viscous dissipation. We model the thickener as rod-shaped fibers, wherein the grease viscosity is reduced by a factor of 5 when the length of a fiber is reduced by a factor of 2.5. The energy needed to break the bonds between the molecules to shorten these fibers is 6 to 7 orders of magnitude smaller than the energy applied by shear. Hence, it is very difficult to measure this fiber structure breakage energy from grease shear aging experiments directly. [ABSTRACT FROM AUTHOR]

The dynamic pressure effect of the clearance oil film of stepped hydrostatic thrust bearing is studied by taking the double rectangular cavity oil cushion as an example. According to the hydrodynamics theory, the dynamic pressure of lubricating oil film in different clearance height regions is theoretically deduced and calculated. The dynamic pressure effect of the clearance oil film in the stepped hydrostatic thrust bearing is studied through the combination of theoretical calculation, simulation, and experimental verification. It is found that the experimental value of the dynamic pressure is between the theoretical value and the simulated value, which is basically not affected by the load. In the speed range of 0 r/min–200 r/min, compared with the viscosity of lubricating oil, the speed is the main factor affecting the dynamic pressure of the oil film of the stepped hydrostatic thrust bearing. The dynamic pressure value of the clearance oil film increases in a stepped fashion along the radial direction of the double rectangular cavity oil cushion. The dynamic pressure value has an obvious upward trend at the junction of the circumferential right oil cavity and the sealing edge and then decreases to 0 after reaching the peak value. [ABSTRACT FROM AUTHOR]

This study presents a theoretical and experimental analysis to quantify the power losses generated by an oil jet lubricated angular contact ball bearing. The analysis is conducted for a moderate speed range (N∙dm product less than 10 6 ) and a limited applied load (<5% of the static capacity). The lubrication regime of each ball is studied through a theoretical model and varies from Iso-Viscous Rigid to Elasto-Hydrodynamic. Therefore, the hydrodynamic effects are considered in the power loss calculation. An experimental campaign is carried out and the influence of several parameters (applied load, oil injection temperature, speed, etc.) is studied. A good agreement is found between the developed model and the measurements. It is shown that the radial applied load has no influence on power losses, unlike speed and axial load. This can be explained by the load distribution and the hydrodynamic rolling contribution on the low loaded balls. [ABSTRACT FROM AUTHOR]

Two quantitative structure–property relationship (QSPR) models of hindered phenolic antioxidants in lubricating oils were established to help guide the molecular structure design of antioxidants. Firstly, stepwise regression (SWR) was used to filter out essential molecular descriptors without autocorrelation, including electronic, topological, spatial, and structural descriptors, and multiple linear regression (MLR) was used to construct QSPR models based on the screened variables. The two models are statistically sound, with R2 values of 0.942 and 0.941, respectively. The models' reliability was verified by the frontier molecular orbital energy gaps of the antioxidants. A hindered phenolic additive was designed based on the models. Its antioxidant property is calculated to be 20.9% and 11.0% higher than that of typical commercial antioxidants methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and 2,2′-methylenebis(6-tert-butyl-4-methylphenol), respectively. The structure–property relationship of hindered phenolic antioxidants in lubricating oil obtained by computer-assisted analysis can not only predict the antioxidant properties of existing hindered phenolic additives but also provide theoretical basis and data support for the design or modification of lubricating oil additives with higher antioxidant properties. [ABSTRACT FROM AUTHOR]

This paper addresses tribotechnical diagnostics, specifically by examining the properties of the engine oil (MO) type i-Sigma top MS; SAE 10W-40 used in the IVECO CROSSWAY bus with a higher number of total mileage from the intervehicle standard. In the abstract of the paper, the characteristics of the measured technique, tribodiagnostic instruments of measurement and a more detailed specification of the oil properties and the monitoring of its gradual degradation during long-term operation are presented. Long-term operation in the sense of the article means a continuous mileage run of more than 200 km (one race without stop) and a MO temperature in the range of 80 °C to 130 °C. All measurements were carried out in the tribodiagnostic laboratory of the Department of Mechanical Engineering of the Armed Forces Academy of General M. R. Štefánik (hereinafter referred to as „AOS") in Liptovský Mikuláš. [ABSTRACT FROM AUTHOR]

The work is devoted to the synthesis and study of new derivatives of alkylxanthateacetic acid, obtained by the interaction of potassium alkylxanthates with allyl ester of monochloroacetic acid. The structure of the synthesized compounds was confirmed by IR and 1H NMR spectroscopy data, as well as by the study of their physicochemical properties, including the determination of the refractive indices and specific gravity and the calculation of molecular refraction based on them, followed by their comparison. It has been established that the synthesized compounds have high extreme pressure properties in transmission oils, while esters of alkylxanthate acetic acid have anticorrosion properties, so they can be used to make prototypes of transmission oils used in various friction units. Using the example of allyl ester of ethylxsanthateacetic acid, the dependence of the yields of the synthesized compounds on the nature of the solvent was revealed. The dependence of the effectiveness of the lubricating properties of the synthesized compounds on the length of alkyl radicals has been revealed. [ABSTRACT FROM AUTHOR]

The numerical simulation method was used to investigate the deflection and deformation process of a circular lubricating oil jet in transverse shear airflow. The numerical model was compared and validated against the experimental data. The physical parameters of Mobil jet Oil II were utilized in this simulation with the nozzle diameter ranging from 0.5 to 2.5 mm, the maximum liquid/gas momentum ratios varying from 10.35 to 165.50, and the injection angle ranging from 0 to 30° in the opposite airflow direction. The results show that an increase in the nozzle diameter decreases the degree of jet deflection. The higher airflow velocity causes more fluctuations in the oil-jet trajectory, while the higher oil-injection velocity reduces fluctuations in the trajectory. The parabolic curve equations were used to derive the trajectory equations for the jet column's pre-disintegration under both vertical incidence and a small angle of reverse airflow. The nozzle diameter and maximum oil/air momentum ratio were used to obtain a formula for the trajectory curve of the lubricating oil. Additionally, a formula for fitting the trajectory curve of oil injected in the opposite airflow direction regarding the injection angle was developed. [ABSTRACT FROM AUTHOR]

Alternative wood preservative technology prevents wood damage and enhances wood service life for local construction in contact with the ground contact. Hence, the promotion of wood preservative technology and the evaluation of knowledge, attitude, and behavioral intention necessitate a causal effect relationship assessment in rural Ethiopia. Farmers were invited for the training in rural kebele, where subterranean termites highly affected local construction with ground contact. During the training, theoretical, demonstration, and group discussion were used as methods for technology transfer. Accordingly, the causal effect relationship of knowledge, attitude, and behavioral intention was evaluated using PLS_SEM using Smart PLS 4 version software. The study results show that, due to local experience, using used motor oil is better preferred over others chemical preservatives. The practical method demonstration influences the attitude of farmers toward future applications. The causal effect analysis result shows that knowledge directly influences attitude (ß = 0.609; P-value = 0.000), and subsequently, an attitude directly influences behavioral intention (ß = 0.822; P-value = 0.000). Thus, attitude mediates the causal effect relationship between the knowledge and behavioral intention of the farmers. Therefore, the study implies that expanding knowledge of local experience and practical training on technical skills for rural farmers should be given primary attention for forest product technology promotion in rural areas. [ABSTRACT FROM AUTHOR]

Nanofluid Minimum Quantity Lubrication (NMQL) is a resource-saving, environmentally friendly, and efficient green processing technology. Therefore, this study employs Minimum Quantity Lubrication (MQL) technology to conduct milling operations on aerospace 7050 aluminum alloy using soybean oil infused with varying concentrations of MoS2 and MWCNTs nanoparticles. By measuring cutting forces, cutting temperatures, and surface roughness under three different lubrication conditions (dry machining, Minimum Quantity Lubrication, and nanofluid minimum quantity lubrication), the optimal lubricating oil with the best lubrication performance is selected. Under the conditions of hybrid nanofluid minimum quantity lubrication (NMQL), as compared to dry machining and Minimum Quantity Lubrication (MQL) processing, surface roughness was reduced by 48% and 36% respectively, cutting forces were decreased by 35% and 29% respectively, and cutting temperatures were lowered by 44% and 40%, respectively. Under the conditions of hybrid nanofluid minimum quantity lubrication, the optimal parameter combination is cutting speed (Vc) of 199.93 m/min, feed rate (f) of 0.18 mm, cutting depth (ap) of 0.49 mm, and nanofluid mass fraction (wt) of 0.51%. The hybrid nanofluid can significantly enhance heat exchange capacity and lubrication performance, thereby improving machining characteristics. [ABSTRACT FROM AUTHOR]

Lubricating oil is easily polluted by solid particles, causing it to deteriorate; therefore, solid particles must be separated from the oil. Furthermore, as conventional filtration devices cannot meet both filtration accuracy and service life requirements, an oil and solid separation method for multi-gradient filtration enhanced by an electric field is proposed. A numerical model for multi-gradient separation was established by coupling the governing equations of electric and flow fields, the particle-wall collision equation, and the discrete phase-tracking equation. Enhanced by an electric field, the characteristics of the multi-gradient filtration of solid particles in oil were investigated using finite element method. The effects of the main control parameters on the filtration performance were analyzed. The results indicate that using the electric field-enhanced multi-gradient filtration method can achieve highly efficient separation of solid particles from the oil. When the electric field strength was increased from 0 kV/mm to 2 kV/mm, the deposition concentration of particles was 2.5 times higher and filtration efficiency of the system increased to 97.46%. Additionally, the deposition concentration and filtration efficiency decreased from 0.15 m/s to 0.3 m/s, while gradually increased from 0.3 m/s to 0.5 m/s, for a particle size range of 10–40 µm. [Display omitted] • An oil and solid separation method for multi-gradient filtration enhanced by an electric field was proposed. • A numerical model for multi-gradient separation enhanced by an electric field was established. • Characteristics of electric field-enhanced multi-gradient of solid particles in oil were investigated. • The effects of the main control parameters on the filter efficiency were analyzed. [ABSTRACT FROM AUTHOR]

A transverse flux linear motor is a special type of linear motor with a high thrust force density, and it has broad application prospects in the field of linear direct-drive systems. In the process of oil production, the vibration of the linear motor poses a significant amount of harm to the system due to its special slender structure. This paper focuses on the electromagnetic vibration of a transverse flux permanent magnet linear submersible motor (TFPMLSM). Firstly, the no-load air gap flux density is calculated based on the field modulation principle. Secondly, the radial electromagnetic force (REF) of the TFPMLSM is calculated, and the finite element method (FEM) is used to analyze the time-space and spectral characteristics of the REF. Then, the influence of secondary eccentricity on the frequency spectrum of the REF is further concluded. Finally, the natural frequencies of each vibration mode are calculated using the modal superposition method and the influence of the REF on the motor vibration is obtained through magnetic-structural coupling analysis. The research results found that the motor does not cause resonance at low speeds, and the fundamental frequency of REF has the greatest impact on electromagnetic vibration. [ABSTRACT FROM AUTHOR]

In this study, dry sliding wear of AlSi0.75TiMnFeCux (x = 0, 0.25, 0.5) high-entropy alloy (HEA) produced through mechanical alloying (MA) and spark plasma sintering (SPS) was studied. The microstructure and phase evolution were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The wear behaviour of HEAs was assessed by reciprocating wear monitor under a dry air atmosphere. The findings demonstrated that AlSi0.75TiMnFeCux HEAs were multiphase body-centred cubic (BCC/B2) solid solution structured with complex µ-, L21, and Laves. It was discovered that the microhardness and wear behaviour of AlSi0.75TiMnFeCux were comparable to AlSi0.75TiMnFe HEA after the addition of Cu up to 0.25 molar ratio. The maximum hardness of the AlCu0-0.5FeMnTiSi0.75 HEAs reached around 1021–1035 HV. The tribology results show that an oxidative wear in AlSi0.75TiMnFe while the mixed adhesive-abrasive wear mechanism was prominent in the AlSi0.75TiMnFeCu0.25-0.5 HEAs. [ABSTRACT FROM AUTHOR]

Two-stroke, low-speed diesel engines are widely used in large ships due to their good performance and fuel economy. However, there have been few studies of the effects of lubricating oils on the vibration of two-stroke, low-speed diesel engines. In this work, the effects of three different lubricating oils on the vibration characteristics of a low-speed engine are investigated, using the frequency domain, time-frequency domain, fast Fourier transform (FFT) and short-time Fourier transform (STFT) methods. The results show that non-invasive condition monitoring of the wear to a cylinder liner in a low-speed marine engine can be successfully achieved based on vibration signals. Both the FFT and STFT methods are capable of capturing information about combustion in the cylinder online in real time, and the STFT method also provides the ability to visualise the results with more comprehensive information. From the online condition monitoring of vibration signals, cylinder lubricants with medium viscosity and medium alkali content are found to have the best wear protection properties. This result is consistent with those of an elemental analysis of cylinder lubrication properties and an analysis of the data measured from a piston lifted from the cylinder after 300 h of engine operation. [ABSTRACT FROM AUTHOR]

Accurate wear debris detection is vital for diagnosing engine wear. However, due to uncertainties in debris behavior, size, and operating conditions, identifying different materials with a single sensor is challenging. To improve sensitivity and accuracy, we propose an integrated detection unit for wear debris in lubricating oil, emphasizing multifunction integration and active intervention. This unit includes a static mixer, a flared transition zone, and a sensor-equipped detection zone. Parametric analysis reveals that debris mixed in the static mixer tends to aggregate toward the center, forming three distinct distribution rings at the detection unit's outlet. A 90° blade angle and a 1:1 aspect ratio enhance the difference in debris quantity between inner and outer rings. To enhance detection reliability, installing capacitive sensors at the front and electromagnetic sensors at the rear of the detection zone can improve the accuracy of detecting different materials debris. This concept offers a multifunctional solution for precise wear debris detection, addressing complex wear scenarios in engines. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the effects of irregular groove textures on the friction and wear performance of sliding contact surfaces. These textures possess multiple depths and asymmetrical features. To optimize the irregular groove texture structure of the sliding contact surface, an adaptive genetic algorithm was used for research and optimization purposes. Design/methodology/approach: Using adaptive genetic algorithm as an optimization tool, numerical simulations were conducted on surface textures by establishing a dimensionless form of the Reynolds equation and setting appropriate boundary conditions. An adaptive genetic algorithm program in MATLAB was established. Genetic iterative methods were used to calculate the optimal texture structure. Genetic individuals were selected through fitness comparison. The depth of the groove texture is gradually adjusted through genetic crossover, mutation, and mutation operations. The optimal groove structure was ultimately obtained by comparing the bearing capacity and pressure of different generations of micro-convex bodies. Findings: After about 100 generations of iteration, the distribution of grooved textures became relatively stable, and after about 320 generations, the depth and distribution of groove textures reached their optimal structure. At this stage, irregular texture structures can support more loads by forming oil films. Compared with regular textures, the friction coefficient of irregular textures decreased by nearly 47.01%, while the carrying capacity of lubricating oil films increased by 54.57%. The research results show that irregular texture structures have better lubrication characteristics and can effectively improve the friction performance of component surfaces. Originality/value: Surface textures can enhance the friction and lubrication performance of metal surfaces, improving the mechanical performance and lifespan of components. However, surface texture processing is challenging, as it often requires multiple experimental comparisons to determine the optimal texture structure, resulting in high trial-and-error costs. By using an adaptive genetic algorithm as an optimization tool, the optimal surface groove structure can be obtained through simulation and modeling, effectively saving costs in the process. [ABSTRACT FROM AUTHOR]

An antimicrobial nanofiber membrane with high efficiency and low resistance for air filtration was prepared using the natural antimicrobial properties of chitosan (CS). To enhance the spinnability performance of CS, CS was treated with alkali to reduce its viscosity. CS/PVA nanofiber membranes were obtained by electrospinning technique using alkali-treated CS and polyvinyl alcohol (PVA) as raw materials. The filtration performance, antibacterial performance and oil-water separation of the CS/PVA fiber membranes were tested. The results show that the chemical structure of CS is not changed after alkali treatment, and the viscosity of CS solution decreases with the increase of alkali treatment time. When the alkali treatment time of CS is 12 h, the CS/PVA fiber membranes are obtained with high filtration efficiency (99.93%) and low filtration resistance (77 Pa), and shows good antimicrobial performance with more than 50% inhibition rate of Staphylococcus aureus. The CS/PVA fiber membrane was then applied to oil-water separation. In the oil-water system, the separation efficiency of the fiber membrane is 99.19%, 99.81% and 99.90% for edible oil, paraffin oil and n-heptane, respectively, and 90.82% for lubricating oil, and the oil-water separation efficiency remains more than 96% after 5 oil-water separation cycles. [ABSTRACT FROM AUTHOR]

Bio-based natural wastes could be considered eco-friendly alternatives to conventional fillers for enhancing the properties and reducing the cost of final rubber products. Thus, in the present research, EPDM/NBR rubber blend composites filled with kaolin and mixed with rice husk fibers (RHFs) were prepared. Homogeneity of the EPDM/NBR blends was improved by the incorporation of maleic anhydride (MAH) as a compatibilizing agent (1 phr), as evidenced by scanning electron microscopy (SEM). Of all EPDM/NBR blend ratios investigated, the 25/75 blend revealed good mechanical properties, thermal stability, and the least weight swell at equilibrium (Q%) in motor oil and brake fluid. EPDM/NBR/kaolin (25/75/30) blend vulcanizates containing RHFs at various loadings demonstrated a significant improvement in swelling resistance, primarily in motor oil and brake fluid, accompanied by a slight reduction in the mechanical properties at high RHFs content. That was complemented by the enhancement of thermal stability of the rubber blends, as demonstrated by TGA analysis. Among the filler types investigated (RHFs, silica ash (SA), rice husk silica (RHS), and kaolin), RHFs exhibited the best swelling resistance of the composite vulcanizates in motor oil and brake fluid. In addition, RHS could be used successfully as a supporting filler for carbon black-reinforced EPDM/NBR composite vulcanizates because it enhanced their thermal stability and swelling resistance in the motor oil. [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]

The Three-Piece Oil Control Ring (TPOCR) is becoming a viable option for heavy duty gas and hydrogen engines due to the low particle concentration in these engines. Although direct oil leakage from the gap is not likely to happen with the misalignment of the upper and lower rail gaps, there exist other less-apparent oil leaking mechanisms through the TPOCR. This work is targeted at understanding the oil leakage's source and destination through the rail and liner interfaces across the whole cycle. The 2D Laser Induced Fluorescence technique was applied on an optical engine to study the oil transport behavior. Combined with a TPOCR model for dynamics and lubrication, the mechanisms that cause rail twist and oil scraping by the upper rail were analyzed. It was found that the symmetrical rail can scrape the oil up in the up-strokes. The scraped oil first accumulates in the clearance between the upper rail and groove, as well as at the upper corner of the rail Outer Diameter before being transferred to both the third land and liner when the piston changes direction at Top Dead Center. Rails with an asymmetrical profile can reduce or enhance these effects depending the orientation of the rails. This study provides findings that could help design the engine to better control Lubricate Oil Consumption and properly lubricate the Top Dead Center's dry region at the same time. [ABSTRACT FROM AUTHOR]

On maritime vessels, external factors such as explosions, collisions, and grounding can cause the emulsification of lubricating oil by seawater pollution, which can affect the lubrication of a ship's thrust bearing. To explore the influence of the mixed emulsification of lubricating oil and seawater on the lubrication performance of thrust bearings, this study conducted an emulsification experiment, from which the viscosity equation of the oil–water mixture was obtained. A thermal hydrodynamic model (THD) of bearings considering oil–water mixed emulsification was established, and the Finite Difference Method (FDM) was used for analysis. The results show that according to the characteristics of the manifold, the mixture is divided into water-in-oil (W/O) and oil-in-water (O/W). In the W/O flow with higher viscosity, the film thickness becomes higher, but the power loss increases. In the O/W manifold with low viscosity, the thin film easily causes mixed friction. In the demulsification stage of the mixed liquid, the thickness loss of the film is huge, and the collision between the thrust-bearing pad and the inference plate may cause the pad to be ablated. The influence of specific heat capacity on temperature is greater than the temperature rise caused by viscosity. [ABSTRACT FROM AUTHOR]

Due to the large size of the bottom surface, the slipper pair of the large displacement piston pump (LDPP) will form a larger linear speed difference in the inner and outer positions of the slipper relative to the center of the swash plate during high-speed rotation. It is more likely to lead to the slipper overturning, which makes the slipper partially worn. To make improvements, the comprehensive performance of the slipper pair of the LDPP, the motion law of the slipper pair of the LDPP was explored. Firstly, a mathematical model of the oil film thickness of the slipper pair of the LDPP under the state of residual compression force is established, based on the consideration of the linear velocity difference formed by the high-speed rotation of the large bottom surface slipper and the theory of dynamics and thermodynamics. Secondly, the impact of rotational speed, piston chamber pressure and oil temperature on the oil film thickness of the slipper pair was simulated and analyzed. Finally, to measure the oil film thickness of the slipper pair, oil film thickness measuring equipment was created, and the accuracy of the mathematical model was verified. The study revealed the changing rules of the oil film thickness and tilt angle of the bottom surface of the slipper pair under various working conditions. The consistency of the simulation and test findings demonstrates that the mathematical model can accurately describe influencing elements and changing rules of the LDPP slipper pair's oil film lubrication characteristics. [ABSTRACT FROM AUTHOR]

In order to accurately and efficiently analyze the distribution law and motion status of lubricating oil in the spiral bevel gearbox of the electric multiple unit (EMU), a high-fidelity 3D CFD model of the spiral bevel gearbox of the EMU was established for the first time. The moving particle semi-implicit method was used to visualize the lubricating-oil flow field distribution characteristics of the gearbox. The distribution characteristics of lubricating oil in the gearbox with varying gear rotation speeds, initial lubricating-oil volume levels and oil temperatures were analyzed. It was found that the initial lubricating-oil volume is the factor with the largest influence, while the influences of gear rotation speed and oil temperature are relatively small. By analyzing the churning loss under various simulation conditions, it was found that the churning loss is positively correlated with the gear rotation speed and initial oil volume, and is more affected by the initial oil volume. The churning loss is negatively correlated with the oil temperature, and both are nonlinear relationships. The proportion of churning loss related to the driven gear is higher compared to that of the driving gear. These results can provide a theoretical basis for the subsequent optimization of the gearbox. [ABSTRACT FROM AUTHOR]

Oil–air lubrication has proven to be very effective for high-speed bearings because the oil supply in the form of droplets can be precisely controlled. This work uses optical interferometry to study the mechanism of lubricating film formation in rolling point contact with oil droplet lubrication. The effect of a double oil drop pair, where two oil droplets are positioned in mirror images about the central axis of the lubricated track, is examined. The process by which pairs of oil droplets approach and lubricate a bearing contact is analysed. This study also covers the effect of multiple oil droplets supplied in a tailored or a random dispersion pattern. Additionally, the effects of oil viscosity, entrainment velocity, and droplet distribution on starvation are also investigated. [ABSTRACT FROM AUTHOR]

This paper examines the difference between the effects of anti-wear additives on vegetable and hydrocarbon-based oils. Knowledge of the specific influence of additives on the anti-wear properties of vegetable oils is necessary to increase the efficiency of the development of biodegradable lubricating oils. In addition, this is interesting from the point of view of clarifying the mechanism of action of AW/EP additives. The effect of non-toxic additives—adipic acid monoester and hexadecanol—on hydrocarbon hydrocracking oil and vegetable oil was compared. The comparison was carried out in rolling contact with sliding, sensitive to the separating ability of the oil. It was found that in hydrocarbon oil, the additive affects the parameters of the hydrodynamic friction regime. When adding an additive to vegetable oil, the hydrodynamic parameters do not change. The additive acts in the same way in both oils during mixed and transient modes. The obtained results are compared to available data, and an explanation of the difference is proposed based on the AW/EP mechanism of action. It is concluded that there is little chance of enhancing vegetable oil properties for hydrodynamic bearings. Search criteria for additives that effectively influence the antifriction and anti-wear properties of vegetable oils in mixed and boundary friction modes are proposed. [ABSTRACT FROM AUTHOR]