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This study aims to evaluate the tribological properties of two protic ionic liquids (PILs) under different tribological conditions as a sustainable alternative for mineral oil-based neat lubricants. The synthesis of PILs in this study uses a relatively simple and less expensive method. The Fourier transform infrared (FTIR) spectroscopy results help validate the synthesised PILs' formation. Further, their physicochemical and tribological properties were investigated. The PILs as neat lubricants were tested on a ball-on-plate reciprocating tribometer using bearing steel–bearing steel and bearing steel–aluminium alloy friction pairs at 30 °C and 80 °C. The results show that the investigated PILs significantly reduced the coefficient of friction and wear. The dodecylamine-based PILs performed better in friction and wear reduction than the other investigated lubricants. The formation of the adsorption layer on the friction pairs was assumed to be the dominant friction and wear reduction mechanism. [ABSTRACT FROM AUTHOR]

The infrastructure construction process cannot be separated from construction machinery; it will inevitably produce wear and tear in the work. The level of wear and tear is severe and could cause mechanical accidents. There are safety hazards involved with wear and tear; thus, the study of the lubrication systems of construction machinery is crucial. This paper addresses the problems with the intelligent lubrication systems of construction machinery and establishes a performance evaluation index system for the intelligent lubrication systems of construction machinery by analyzing and selecting appropriate evaluation indexes. Based on the built evaluation system, a performance evaluation model was established based on the hierarchical analysis (analytic hierarchy process, AHP)–entropy weight method and a topological object element model. The feasibility of the model was tested using the example of an off-road mining dump truck. This model analyzes the performance strengths and weaknesses of smart lubrication systems and suggests improvement measures and recommendations for weak links. It also provides a reference for analyzing the performance of smart lubrication systems for other mechanical devices. [ABSTRACT FROM AUTHOR]

The flow field around the grinding wheel prevents grinding fluid from entering the grinding area, which deteriorates machining conditions and reduces the quality of the workpiece. MQL (Minimum Quantity Lubrication) grinding uses compressed gas to improve the ability of the grinding fluid to pass through the flow field of the grinding wheel so that a small amount of the grinding fluid can meet the cooling and lubrication requirements and reduce the cost of using grinding fluid. In this study, we investigated the flow field of grinding wheels under MQL conditions and obtain the rules that influence factors such as grinding fluid flow rate, grinding wheel linear speed and compressed gas pressure affect the flow rate of grinding fluid. The simulation method was used to simulate the flow field of the grinding wheel and the trajectory of the grinding fluid droplets. The simulation results show that these factors are important ones affecting the effective flow rate of grinding fluid. Meanwhile, the experimental results verify that these factors have the same influence pattern on the effective flow rate and grinding temperature. [ABSTRACT FROM AUTHOR]

Thin film formation of lubricant plays a key role in supporting lubrication and abating wear. During cold rolling of steel, esters, or film formers in rolling oil play an important role in the mixed lubrication regime. The property of the lubricant holds the key to achieving the mean film thickness during the mixed lubrication regimen. Band formation in cold rolling is often related to inadequate acid pickling. During cold rolling operation, the film formation between asperities plays an important role in controlling friction and coil temperatures. A well formulated lubricant ensures smooth transition of lubrication throughout the range of roll bite temperature and also across the lubrication regimes. A sudden spike in coefficient of friction (CoF) can often lead to increased wear and abnormal increase in coil temperatures resulting in band formation. The study highlights degradation of oil sample leading to the problem and the role of key lubricant properties in esters in mitigating the problem. [ABSTRACT FROM AUTHOR]

Oral processing is not only a dietary process, but also a pleasure seeking process. The texture of food perceived by people is a multidimensional sensory characteristic. At present, rheology is no longer able to characterize this complex sensory perception. Tribology objectively characterizes the sensory properties of food in oral processing by simulating the processing process of food in the mouth and the lubrication behavior of food when pressed onto the surface of the mouth by the tongue. Oral tribology has become an important tool for characterizing the lubrication behavior in food oral processing. This article reviews the application of oral tribology in food processing and research and development, focusing on the sensory perception and lubrication mechanism of food in oral processing, such as astringency and lubrication, with the aim of providing reference for future food design. [ABSTRACT FROM AUTHOR]

The main goal of this research is to compare the rheological behavior of hybrid nano lubricants (HNLs) with different composition ratios in a base oil. The purpose of the comparison is to determine the HNL with the best lubrication performance at the start of the vehicle. Theoretical methods have confirmed the non-Newtonian behavior in different laboratory conditions. HNLs with the composition ratio of 30:70 and 25:75 had the highest percentage of increase and decrease in viscosity, respectively 34.97% and − 1.85% at T = 55 °C, shear rate SR = 6665 s−1 and solid volume fraction SVF = 1% and T = 5 °C, SR = 3999 s−1 and SVF = 0.05%. To predict the viscosity of the desired HNL, in the RSM, a special model with an accuracy of R2 = 0.9997 has been used. The margin of deviation (MOD) is determined in the range of − 3.43% < MOD < 4.75%. Viscosity sensitivity analysis shows that the greatest sensitivity will result from SVF changes at high SVFs. The experimental results of this study will introduce the optimal nano polishing to the craftsmen, and the theoretical part of this study will save the researchers from spending time and excessive economic costs. [ABSTRACT FROM AUTHOR]

Plain bearings, renowned for their versatility and simplicity, are extensively utilized in engineering design across various industries involving moving parts. Lubrication is vital to the functioning of these bearings, yet their usage is inhibited under dynamic load conditions, or at elevated or reduced temperatures due to this dependency on lubrication. This study introduces an innovative method to significantly mitigate friction and wear in plain bearings operating without lubrication. The plain bearings were constructed from steel–bronze pairs, where the steel shafts were alloyed with bismuth oxide via short-pulse laser treatment. MnO2 was utilized as a carrier to incorporate the bismuth oxide into the surface layers of the steel. Insights from transmission electron microscopy and X-ray photoelectron spectroscopy revealed a highly non-equilibrium state of matter, unattainable through conventional engineering methods. The tribological performance of the modified steel disks was assessed via a block-on-ring sliding test, demonstrating superior wear and friction performance without lubrication, as well as an ultra-low coefficient of friction. Remarkably, the modified friction pairs remained functional after 200 km of linear sliding at a load of 250 N (12.5 MPa) and a sliding speed of 9 m/s. To substantiate the technique's viability, we tested the performance of an internal combustion engine turbocharger fitted with a modified steel shaft. The turbocharger's performance validated the long-term effectiveness of the steel–bronze coupling operating without lubrication at 75,000 rpm. The simplicity and resilience of this technique for modifying steel–bronze pairs offer a ground-breaking and promising approach for a wide range of applications. [ABSTRACT FROM AUTHOR]

The service conditions of high temperature and heavy load of aero-engine require high-temperature self-lubricating composites with high strength, low wear and long life. Hence, the high-level objective of this study is to regulate the interface between the substrate and hexagonal boron nitride (h-BN) lubricant in GH4169 nickel-based high-temperature self-lubricating composites to improve the interfacial bonding strength and the overall performance. Electroless plating method was adopted to coat nickel on h-BN, and the dense high-temperature self-lubricating composites were fabricated through hot-pressing sintering. The effects of nickel coating on h-BN on the microstructure, mechanical properties and high-temperature tribological behaviors of composites were analyzed in detail, and the lubrication mechanism was also elucidated. The results illustrate the Ni@h-BN/GH4169 composites with addition of chemically modified lubricant particles have excellent mechanical properties and lubrication and wear reduction properties, compared to h-BN/GH4169 composites. This is mainly due to the introduction of nickel coating contributed to the distribution uniformity of h-BN in the matrix, and the wettability between h-BN and the substrate together with interfacial bonding strength were enhanced as well. This work provides an insight to overcome the challenges facing the technology when using GH4169 nickel-based self-lubricating composites in manufacturing of mechanical components in aerospace. [ABSTRACT FROM AUTHOR]

Phosphorene, a single layer of black phosphorus, is attracting interest for several applications, among which tribology. Here, we investigate its possible use as a solid lubricant for iron-based materials by comparing its friction-reduction properties with MoS 2 and graphene. Through first-principle calculations, we predict that phosphorene adheres more strongly to the native iron surface than the other considered 2D materials. The higher adhesion suggests that a stable and durable coverage of reactive surface regions can be obtained with phosphorene. Furthermore, our simulation uncovers the peculiar behavior of phosphorene to exfoliate into two atomic-thin layers upon interface intercalation. This capability makes phosphorene reduce the nano-asperity adhesion very efficiently thanks to the simultaneous passivation of the surface and countersurface. These results suggest that better performances could be obtained by phosphorene than other solid lubricants at low concentrations. [ABSTRACT FROM AUTHOR]

Rotary compressors are widely used in split air conditioning units and have a significant global market share. However, the atomization of lubricant in the rotary compressor during discharge from the cylinder can cause negative effects on both heat transfer performance and reliability. Therefore, it is crucial to deepen the understanding of the behavior of atomized oil in the form of small droplets in order to improve the system's performance. In this study, lubricant droplets were analyzed at different locations, operating frequencies, and pressures using shadowgraph imaging. The droplets were extracted using the Canny operator and corrected using a Convolutional Neural Network, and their sizes were analyzed statistically. The results reveal that the droplet characteristic mean diameters increase with frequency and pressure, with larger sizes observed in the outer region above the rotor/stator and constant sizes in the radial direction at the discharge tube level. Additionally, the droplet's volume fraction increases with frequency, with higher values observed in the outer region above the rotor/stator and above the rotor/stator clearance at the discharge tube level. These findings provide valuable experimental data for setting up the boundary conditions used in computational fluid dynamics (CFD) simulations. • An algorithm to identify oil droplets from images recorded in the rotary compressor. • Oil droplet size versus frequency, pressure, and locations are measured in-situ. • The volume fraction of oil droplets is experimentally quantified. [ABSTRACT FROM AUTHOR]

The controllable character of the melting point of deep eutectic solvents (DESs) makes it easy to realize lubricated state transitions and produce excellent lubricating properties during friction. In this work, a series of novel imidazole-based DESs were synthesized to present a room-temperature solid state by shifting its eutectic point. Tribological test results show that the wear volume of these DESs decreases as the alkyl chains of the hydrogen bond donors increase. A proper deviation of the eutectic point in DESs produces stable lubricating properties. The present work provides a novel and simple method to prepare solid lubricants and enriches the use of DESs as lubricants. Simultaneously, the method expected to replace the use of conventional cutting fluids. [ABSTRACT FROM AUTHOR]

Indication of the proper scope of application of high-speed steels (HSS) produced by conventional methods and powder metallurgy for cutting tool blades requires a thorough assessment of their properties in various cutting conditions. According to common knowledge, the properties of tools made of both types of steel are largely determined by the arrangement of carbide phases. It turns out, however, that the surface morphology of the cutting blades is at least as important for their operational properties. This was already indicated by the preliminary research of the authors of the article, in which it was found that the surface topography significantly affects their durability depending on the applied value of the cutting speed in dry machining conditions and in the presence of a cooling lubricant. As it turned out, contrary to the literature data, blades made of sintered HSS do not have better service properties in all cutting conditions than blades made by conventional methods (e.g., in forging and hot rolling processes). Hence, it was necessary to determine the justified range of use of both types of steel for cutting blades. Cutting blades with a similar chemical composition from conventional high-speed steel and those produced in the powder metallurgy process were tested. Wear curves were determined on the basis of the tests. On this basis, for the assumed value of the blunting index, the tool life of the cutting edges was determined during the cutting of selected structural steel, commonly used for high-strength machine parts. Tests of the cutting ability of the blades were carried out without and with the use of a cooling--lubricating liquid. In order to correctly interpret the obtained results of the wear and durability tests of the cutting edges, verification tests were carried out. A detailed analysis of the research material made it possible to determine the recommended range of applicability of conventional and sintered HSS for the tested case. [ABSTRACT FROM AUTHOR]

Introduction: Tablets are commonly produced by internally adding particulate lubricants, which are known to possibly lower the mechanical strength of tablets. This reduction is caused by the coverage of matrix forming components by lubricant particles, resulting in decreased interparticulate interactions. The known incompatibilities with some active compounds of the predominantly used lubricant, magnesium stearate, call for the in-depth characterization of alternative lubricants. Purpose: Investigation of the dispersion behavior of five commonly applied pharmaceutical lubricants by mathematically modeling the dispersion kinetics for short and extended mixing times. Methods: The dispersion behavior of five different pharmaceutical lubricants were examined by systematically varying lubricant concentration and mixing time of binary formulations and evaluating the kinetic of tensile strength reduction by theoretically estimating the surface coverage based on particle sizes. Results: For short mixing times, a unifying relationship between compactibility reduction and theoretical surface coverage was identified. Subsequently, for extended mixing times, distinct differences in the shear strength and dispersion kinetics of the investigated lubricants were found. Conclusions: The lubricant particle size controls the tensile strength reduction if short mixing times are applied. For extended mixing times, the investigated lubricants can be divided into two groups in terms of dispersion kinetics. Possible underlying reasons are discussed in detail in order to enhance the general understanding of lubricant dispersions in tablet formulations. [ABSTRACT FROM AUTHOR]

In this study, plastic oil (PO) as a potential lubricant was investigated. The base PO was incorporated with graphene nanoplatelets (GNP) and hexagonal boron nitride (hBN) nano additives in varying concentrations to form nano lubricants. Their viscosity, tribological, acidic/basic nature, thermal degradation and dispersion stability properties were investigated. It was observed that 1.5 wt% GNP and 1.0 wt% hBN added separately to the base PO, provided the lowest coefficient of friction (COF) and wear volume. Based on these lowest COF and wear volume insights, three nano lubricant mixtures were formulated by incorporating both GNP and hBN at different combinations using base PO. Positive synergistic behaviour was observed for COF (49%–60% reduced) and wear volume (90%–97% reduced) for two combination mixtures compared to the base PO. These improvements in the mixture were due to the polishing, mending mechanisms and tribofilm that protected the interacting surfaces. [ABSTRACT FROM AUTHOR]

Porous materials are widely used in friction pairs. The transient squeezing flow of the lubricant significantly affects the lubrication quality. The study found that the lubricant penetrates into the porous matrix in the contact area and exudes upward to the entrance of the contact area. The maximum stress occurs at the subsurface of the contact zone, and the maximum pressure occurs at the contact centre. In the early loading stage, the lubricant exudates, resulting in a higher liquid‐phase load. With the prolongation of the time, the average stress decreases and then increases gradually, whilst the average pressure has the opposite change. In the late loading stage, the load is completely borne by the solid phase. Increasing the load will increases the seepage velocity of the lubricant, which enhance the pumping effect of the friction interface. The findings can help for better understanding of the self‐lubrication mechanism of the porous materials. [ABSTRACT FROM AUTHOR]

To reduce the lubrication failure of water-lubricated bearings under short-term harsh conditions, preliminary experiments have shown that temporarily supplying a small amount of lubricating oil into a bearing as a secondary lubricant can improve the load capacity of the water film therein. However, the physical flow and diffusion state of this secondary lubricant (oil) in water are unclear. Therefore, a mixed lubrication model and a volume-of-fluid model are incorporated to study the diffusion behavior of a small amount of lubricating oil in a water-lubricated bearing. The results show that there is a backflow effect in the local area inside the bearing, where the fluid velocity is in the opposite direction to the linear velocity of the shaft. This backflow effect intensifies with increasing eccentricity ratio, which enlarges the oil-free zone in the middle part of the bearing. In the convergence area at the water inlet end of the bearing, the water supply pressure and backflow effect prevent the lubricating oil from escaping. Increasing the shaft speed has a positive effect on the diffusion of the oil and the load capacity of the fluid. To enhance the assisted lubrication effect of the oil, the oil injection port should be set in the loading zone to avoid the backflow zone. This research provides some fundamental data for reducing the friction and wear of water-lubricated bearings under harsh conditions. [ABSTRACT FROM AUTHOR]

The article substantiates the effect of the concentration of polymer thickener on such basic properties of the plastic lubricant as dripping temperature (td.p., ℃) and adhesive properties (ADG). It was defined that, unlike (td.p., ℃), the ADG indicator is more informative for defining the optimal concentration of the polymer thickener in plastic lubricants produced from secondary raw materials. Determination of the ADG indicator was performed in a laboratory centrifuge, based on the amount of plastic lubricant that remained on the metal plate after the study. This amount should be at the level of 50 % of the initial value. Experimental studies have shown that the optimal concentration in the composition of the lubricant is: in the case of HDPE, 5.0 % for SAE15W-40 oil, 4.3 % for SAE 75W-90 oil, 6.3 % for BP Energol CS68 and HLP-46 oil; in the case of LDPE, this concentration is equal to 7.0 % for SAE15W-40 oil, 5.2 % for SAE 75W-90 oil, 7.4 % for BP Energol CS68 and HLP-46 oil; in the case of PP, this concentration is equal to 7.5 % for SAE15W-40 oil, 6.2 % for SAE 75W-90 oil, 8.0 % for BP Energol CS68 and HLP-46 oil. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The machining ability and accuracy of a machine are determined by parameters such as the stiffness and load capacity of its spindle unit. In addition, the effectiveness and technique of lubrication and cooling can significantly affect the operational characteristics of the machine spindle. The current study investigated the effects of two different lubrication methods, grease and air-oil mixture, on the temperature which is generated at the spindle bearings of a Computer Numerical Control (CNC) machine. The temperature distribution and rise rate of the bearings were measured using a thermal imaging camera and thermocouples. The results indicated that the air-oil mixture method was more effective in dissipating heat and reducing the temperature of the bearings than the grease method, due to the direct cooling provided by the air-oil mixture to the bearing balls, resulting in improved lubrication efficiency and heat exchange with the environment. Compared to the grease lubrication method, the temperature of the bearings was lower by 7°C to 9°C depending on the position of the bearing on the CNC spindle. Therefore, it is recommended to use the air-oil mixture lubrication method, especially for high-speed processing on CNC machines. However, the discharge of oil particles from the ventilation system should be carefully controlled. Overall, the findings offer valuable insights into optimizing lubrication methods for CNC machines to enhance processing quality and reduce the impact of temperature on the bearing performance. [ABSTRACT FROM AUTHOR]

Preventing surface damage is crucial for optimal machine performance, with lubricants and additives playing a vital role in achieving this objective. This study specifically focuses on evaluating the influence of fly-ash additives on the wear resistance of machine components when incorporated into lubricant oil. The experiments were conducted following ASTM standard operating conditions, utilizing the four-ball wear test to measure the scratch width and weight loss of balls using different lubricant oil formulations, including 0, 0.1%, 0.5%, 0.75%, and 1% additive. The findings demonstrate that the inclusion of 0.5% fly ash additive in the lubricant oil results in a significant reduction in both scratch width and weight loss of the balls. However, it should be noted that higher additive ratios may lead to increased scratch width and weight loss due to the agglomeration of the fly ash particles on the sliding surfaces. To achieve optimal effectiveness in reducing friction and wear, it is recommended to carefully control the content of fly ash within an appropriate range. Furthermore, this study highlights the width of scratches on balls as a reliable indicator for assessing the anti-wear properties of oils. The insights gained from this research offer valuable guidance to manufacturers in the selection of suitable anti-wear oils for specific applications. Further investigations could explore the impact of different lubricants and additive ratios to identify the most appropriate lubrication parameters. Overall, this study contributes to a better understanding of the effects of fly ash additives on the performance of lubricant oil and provides practical guidance for optimizing lubrication strategies in diverse industrial contexts. [ABSTRACT FROM AUTHOR]

With the growth of the wind industry in the world and the commissioning of turbines with powers higher than 1 MW, higher loads and increased stresses have a strong effect on the durability of the bearings that equip the main shaft and the kinematic transmission of wind turbine gears. As a result, the wind industry is demanding greater durability of the bearings that equip the main shaft and the kinematic transmission with gears, and manufacturers are striving to come up with solutions for these requirements. The novelty in this work consists in the identification of some solutions, as well as improvements of the existing solutions for the construction of some mechanical systems for the existing wind turbines. We present below some constructive bearing solutions that are effective in the wind turbine industry. The research in the paper consists of: stress analysis of the loadbearing structure for the axial radial bearing with straight rollers with single ring, some aspects about lubrication of blade bearing in wind turbine and defects in blade bearings. [ABSTRACT FROM AUTHOR]

The growing awareness of reduced friction losses and new demands for electrical powertrains demand improved lubricants. Due to their unique properties, such as high thermal and electrical conductivity, graphene and its derivatives have been investigated for tribological applications, especially as lubricant additives. In this work, we investigated three commercially available graphene variants, one comprising a few layers and the other two comprising nanoplates, after functionalization as additives to lithium soap grease. The grease temperature dropping point increased by approximately 6 °C. Additionally, during the reciprocating friction test, friction increased with the test duration for the baseline grease, whereas it decreased for the ones containing graphene-based additives. On the test end, friction was reduced by 8% compared to the baseline grease. On a four-ball tribometer, the wear scar was reduced from 10 to 18% compared to the baseline grease. In general, no significant difference was seen between the three graphene-based variants. The promising results found with graphene nanoplates, a less expensive material than a few graphene layers, creates opportunities for a cost-competitive additive to commercial greases. [ABSTRACT FROM AUTHOR]

Optimizing input parameters not only improves production efficiency and processing quality but also plays a crucial role in the development of green manufacturing engineering practices. The aim of the present study is to conduct a comparative evaluation of the cutting performance and machinability process during the turning of AISI 4340 steel under different cooling conditions. The study analyzes cutting operations during turning using dry, minimum quantity lubrication, and nano- minimum quantity lubrication. As control parameters in the experiments, three different cooling types, cutting speeds (100, 150, 200 m/min), and feed rate (0.1, 0.15, 0.20 mm/rev) levels were applied. The experimental results show that the optimal output values are found to be Vb = 0.15 mm, Ra = 0.81µm, 88.1 dB for sound intensity and I = 4.18 A for current. Moreover, variance analysis was performed to determine the effects of input parameters on response values. Under dry, minimum quantity lubrication, and nano-minimum quantity lubrication processing conditions, parameters affecting tool wear, surface roughness, current by the motor shaft, and sound level were examined in detail, along with the chip morphology. The responses obtained were optimized according to the Taguchi S/N method. As a result of optimization, it was concluded that the optimum values for cutting conditions were nano-minimum quantity lubrication cooling and V = 100 m/min, f = 0.1 mm/rev cutting. Finally, it was observed that there was a 13% improvement in tool wear, 7% in current, 9% in surface roughness, and 8% in sound intensity compared to the standard conditions. In conclusion, it was determined that nano-minimum quantity lubrication with the lowest level of cutting and feed rate values provided the optimum results. [ABSTRACT FROM AUTHOR]

As nanotechnology has developed, some nano-additives have been employed to improve the performance of lubricants. The mechanisms of nano-additives still need to be investigated. The wear characteristics of Fe3O4 nano-additive lubricant were investigated in this study. Different diameters of Fe3O4 nanoparticles were mixed in basic oil using an ultrasonic mixer. The new lubricant was used for analytical tests at room temperature. The results showed that nano-lubricants with 20 nm nanoparticles increase the oil film strength. The coefficient of friction was reduced when 20 nm diameter 8 wt% Fe3O4 nanoparticles were mixed with lubricants. The effect of surfactants and nanoparticles in the base oil was measured using numerical simulation methods. The adsorption capacity of the lubricants was significantly improved by Fe3O4 nanoparticles, particularly when looking at the small relative atomic mass of the metal. The 8 wt% Fe3O4 lubricant exhibited optimal tribological properties when applied in micro-rolling tests. The results showed that the surface quality of the rolled samples was significantly improved, and the rolling force was dramatically reduced. At the same time, the shapes of the samples were effectively controlled in the rolling process. Therefore, Fe3O4 nanoparticles can improve the friction and wear characteristics of lubricants. [ABSTRACT FROM AUTHOR]

Minimizing the negative effects of the manufacturing process on the environment, employees, and costs while maintaining machining accuracy has long been a pursuit of the manufacturing industry. Currently, the nanofluid minimum quantity lubrication (NMQL) used in cutting and grinding has been studied as a useful technique for enhancing machinability and empowering sustainability. Previous reviews have concluded the beneficial effects of NMQL on the machining process and the factors affecting them, including nanofluid volume fraction and nanoparticle species. Nevertheless, the summary of the machining mechanism and performance evaluation of NMQL in processing different materials is deficient, which limits preparation of process specifications and popularity in factories. To fill this gap, this paper concentrates on the comprehensive assessment of processability based on tribological, thermal, and machined surface quality aspects for nanofluids. The present work attempts to reveal the mechanism of nanofluids in processing different materials from the viewpoint of nanofluids' physicochemical properties and atomization performance. Firstly, the present study contrasts the distinctions in structure and functional mechanisms between different types of base fluids and nanoparticle molecules, providing a comprehensive and quantitative comparative assessment for the preparation of nanofluids. Secondly, this paper reviews the factors and theoretical models that affect the stability and various thermophysical properties of nanofluids, revealing that nanoparticles endow nanofluids with unique lubrication and heat transfer mechanisms. Finally, the mapping relationship between the parameters of nanofluids and material cutting performance has been analyzed, providing theoretical guidance and technical support for the industrial application and scientific research of nanofluids. [ABSTRACT FROM AUTHOR]

The thermophysical, rheological, and tribological properties in lubricant are essential for preserving the engines, power steering systems, and engine components from damage caused by friction and wear. The incorporation of nano-sized particles into lubricating oils has been reported to enhance these properties. Therefore, this study explores the impacts resulting from the incorporation of graphene, multiwalled carbon nanotubes (MWCNT), doublewalled carbon nanotubes (DWCNT), and single-walled carbon nanotubes (SWCNT) at a quantity of 0.04 grams into the SAE 5W-30 base oil. These nanoparticles were synthesized using a two-step method, resulting in nanolubricants. The addition of carbon-based nanomaterials increases the density and decreases the viscosity of the base lubricant. The flow of nanolubricants exhibits non-Newtonian shear thinning behavior during the test at elevated temperatures. The results of the four-ball tribo-tester test reveal the increase of Coefficient of Friction (CoF) values and the extent of wear scar area. Further, the Scanning Electron Microscopy (SEM) analysis was employed to observe the wear morphology of the nanolubricants on the SKF RB-12.7/G20W ball bearing. Its results indicate a prevalence of groovetype wear as compared to conventional lubricants. [ABSTRACT FROM AUTHOR]

In general anesthesia surgery, endotracheal intubation is used to maintain the patient's airway smoothness, which may cause respiratory tract damage and cause postoperative sore throat. This project was initiated as a result of continuous complaints from patients regarding severe postoperative throat pain. After investigation, it was found that patients with endotracheal intubation under general anesthesia had a moderate to severe postoperative throat pain rate of 43.3%. A task force investigated the current situation and determined the main causes as endotracheal tube balloon fixation and monitoring operations not being standardized. Issues identified included: Anesthesiologists different perceptions of lubricant use during intubation; inadequate use of auxiliary tools and materials; a lack of auxiliary resources for health education; and a lack of audit and improvement mechanism. The methods implemented for improvement included: unifying airbag fixation and monitoring methods; obtaining a consensus on the use of lubricants; producing patient information leaflets; revising the safety operation process of endotracheal intubation; and developing an audit process on endotracheal intubation. After the execution of the improvement strategy, the occurrence of postoperative sore throat dropped from 43.3% to 30.0%, demonstrating effective improvement in the quality of anesthesia care. [ABSTRACT FROM AUTHOR]

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

While many injectable viscosupplementation products are available for osteoarthritis (OA) management, multiple hydrogel functional attributes may be further optimized for efficacy enhancement. The objective of this study was to functionally benchmark four commercially available hyaluronan-based viscosupplements (Ostenil, Ostenil Plus, Synvisc, and Innoryos), focusing on critical (rheological, lubricative, adhesive, and stability) attributes. Therefore, in vitro and ex vivo quantitative characterization panels (oscillatory rheology, rotational tribology, and texture analysis with bovine cartilage) were used for hydrogel product functional benchmarking, using equine synovial fluid as a biological control. Specifically, the retained experimental methodology enabled the authors to robustly assess and discuss various functional enhancement options for hyaluronan-based hydrogels (chemical cross-linking and addition of antioxidant stabilizing agents). The results showed that the Innoryos product, a niacinamide-augmented linear hyaluronan-based hydrogel, presented the best overall functional behavior in the retained experimental settings (high adhesivity and lubricity and substantial resistance to oxidative degradation). The Ostenil product was conversely shown to present less desirable functional properties for viscosupplementation compared to the other investigated products. Generally, this study confirmed the high importance of formulation development and control methodology optimization, aiming for the enhancement of novel OA-targeting product critical functional attributes and the probability of their clinical success. Overall, this work confirmed the tangible need for a comprehensive approach to hyaluronan-based viscosupplementation product functional benchmarking (product development and product selection by orthopedists) to maximize the chances of effective clinical OA management. [ABSTRACT FROM AUTHOR]

In recent years, the quest for effective lubrication in micro deep drawing (MDD) has seen promising advancements. In this study, the influence of TiO2 nanolubricants and graphene lubricants on the performance of 301 stainless steel foil in MDD is examined. The MDD undergoes an extensive evaluation of various lubrication conditions, including dry, TiO2 nanolubricant, graphene lubricant at concentrations of 2.5 mg/mL, 5.0 mg/mL, and 10.0 mg/mL, as well as combined applications of TiO2 and graphene lubricants. Utilising a 5.0 mg/mL graphene lubricant together with TiO2 nanolubricants led to a significant reduction in drawing force, highlighting the synergistic efficacy of this combined lubricant. A pronounced enhancement in the consistency of the produced microcups was also attained. These results emphasise the promise of TiO2 nanolubricant and graphene lubricants in optimising the MDD process. [ABSTRACT FROM AUTHOR]

In this study, we synthesized three low-sulfur and low-phosphorus ionic liquids (ILs). These were N88816P8, P88816P8, and P88816DOSS. The viscosity and thermal stability of the three ILs were analyzed. The tribological properties and lubrication mechanisms of the three ILs were investigated as lubricants for a carbide ball–Inconel 690 nickel-based alloy friction pair and compared at 50 °C and 150 °C. The wear spots of the carbide ball and nickel-based alloy disc samples were characterized using SEM and EDS. The experimental results revealed that P88816P8 had excellent tribological properties. The lubrication mechanism of P88816P8 as a lubricant for the carbide ball–Inconel 690 nickel-based alloy friction pair was investigated using XPS. The excellent friction reduction and anti-wear properties of P88816P8 could be attributed to the tribo-chemistry between P88816P8 and Inconel 690 as well as the formation of a tribo-film on the wear-spot surface. This high-performance IL, suitable for carbide ball–Inconel 690 contact, will be applied to a cutting process of Inconel 690. [ABSTRACT FROM AUTHOR]

The enhanced surface mobility in metallic glasses (MGs) has been a constant source of fascination due to its unique mechanical properties. We show experimentally that the mobile surface layer of MGs functions as a lubricating layer in friction experiments, which is evidenced by a reduction of a friction coefficient of 50% or less and suppression of dissipative stick-slip behavior with decreasing scratch depth down to nanoscale in the various MGs. The lubrication mechanism could be attributed to easier shearing of the mobile surface layer induced by homogeneous plastic flow. Importantly, the thickness of the self-lubricating layer is inversely proportional to glass transition temperature with a higher homologous temperature yielding a larger thickness. These results extend the fundamental understanding of the ubiquitous MG surface and present a path for the rational design of self-lubricating materials. [ABSTRACT FROM AUTHOR]

Nowadays, one of the most important challenges in the tribology field is to avoid the excessive consumption of soft metals such as Ag at elevated temperatures through the re-design of the self-lubricant films, to achieve the long-term lubricant under the temperature-cycling environments, for widely used in real industrial applications. This paper took up this challenge to develop a novel green film, by composing nano-particles Ag into the amorphous SiN x matrix using magnetron sputtering system, for achieving the long-term lubricant under the room temperature (RT)-500 °C temperature-cycling conditions. Results showed that the film exhibited a dual-phase of face-centered cubic (fcc) Ag and amorphous SiN x. An excellent RT-500 °C wear-resistance performance was observed for the films with the Ag content of 1.3–9.4 at.%, whilst the film at 15.8 at.% Ag exhibited the best anti-frictional performance (COF 0.3–0.5 for RT-500 °C conditions) at the cost of wear rate. The self-lubricant tribology behaviors under the RT-500 °C cycling conditions were mainly attributed by the synergism of: (1) mechanical properties, (2) excellent high-temperature chemical stability of SiN x matrix, and (3) the lubricant nature of Ag and its elevated temperature diffusion behaviors. [ABSTRACT FROM AUTHOR]

Polyimide (PI) is a high-performance engineering plastic used as a bearing material. A superlubricity system using Si3N4/PI as the friction pair and nematic liquid crystals (LCs) as the lubricant was designed. The superlubricity performance was studied by simulating the start-stop condition of the machine, and it was found that the superlubricity system had good reproducibility and stability. In the superlubricity system, friction aligned with the PI molecules, and this alignment was less relevant compared to which substance was rubbing on the PI. Oriented PI molecules induced LC molecule alignment when the pretilt angle was very small, and the LC molecules were almost parallel to the PI molecules due to the one-dimensional ordered arrangement of LC molecules and low viscosity, which is conducive to the occurrence of the superlubricity phenomenon. [ABSTRACT FROM AUTHOR]

Conventional lubrication systems are used in grinding operations to reduce friction and defects produced during machining. Mineral-based oils, commonly used as conventional lubricants, were observed to produce greenhouse wastes that are hazardous to the environment. The minimum quantity lubrication (MQL) system, an eco-friendly, economical, and less hazardous lubrication technique, is affirmed to be an efficient substitute for these conventional lubricants. Nevertheless, the pure vegetable and synthetic oils used in MQL systems have lower tribological and thermal evacuation properties compared to conventional lubricants. Many adjustments and improvements have been introduced into the MQL system such as the introduction of nanofluids, cryogenic air, ionic fluids, and electrostatic atomization. This study aims to come up with an extensive review and analytical assessment of the trends and developments of the MQL system in grinding operations. Firstly, the different advances ranging from fluid types, additives, and redesigns of the MQL systems are discussed. Likewise, the results obtained from using different types of lubricants and nanofluids in the MQL system were discussed. Moreover, a detailed comparative assessment of the grinding performances between the MQL systems, dry grinding, and conventional lubrication was provided. It was found that the nanofluid MQL system produced 60% lower surface roughness and reduced the grinding forces by 30% compared to flood cooling systems. Lastly, the area of focus for research on grinding with MQL system for future advancements was proposed. The various advancements include the introduction of nanofluid varieties and the overall modification of the grinding system. [ABSTRACT FROM AUTHOR]

An aero-engine's cost, weight, and complexity can be greatly reduced if fuel is used for lubrication instead of oil. However, there are not many published works about the effect of fuel lubrication on the rolling element bearings' motion. This research analytically investigates the effects of kerosene lubrication on the cage slip, heat generation, and temperature of a cylindrical roller bearing. We developed an in-house program composed of a simplified quasi-static model to predict the cage slip and a thermal network model to predict the bearing's heat generation and temperature. The in-house program was verified with respect to data from previous researches. Four types of lubrication were investigated using the in-house program: under-race lubrication by oil, under-race lubrication by fuel, jet lubrication by oil, and jet lubrication by fuel. We conducted a parametric study by changing the bearing's rotational speed, lubricant flowrate, and inlet lubricant temperature to compare the kerosene lubrication of an imaginary aircraft engine bearing to conventional oil lubrication. [ABSTRACT FROM AUTHOR]

In the present work, the functionalisation of austenitic stainless steel, AISI 316L surfaces via nanosecond Nd:YAG laser texturing in order to modify the surface morphology with crosshatch and dimple patterns is presented. A tribological analysis under lubrication with sunflower and jojoba oil with and without the addition of a solid lubricant, MoS2 nanotubes, was performed. In conjunction with friction/wear response laser-textured surface wettability, oil spreadability and oil retention capacity were also analysed. It was shown that the crosshatch pattern generally exhibited lower friction than the dimple pattern, with the addition of MoS2 nanotubes not having any significant effect on the coefficient of friction under the investigated contact conditions. This was found in addition to the better oil spreadability and oil retention capacity results of the crosshatch-textured surface. Furthermore, texturing reduced the wear of the stainless-steel surfaces but led to an approximately one order of magnitude larger wear rate of the steel counter-body, primarily due to the presence of hard bulges around the textured patterns. Overall, the crosshatch pattern showed better oil retention capacity and lower friction in combination with different vegetable oils, thus making it a promising choice for improving tribological performance in various environmentally friendly applications. [ABSTRACT FROM AUTHOR]

The present study reports the tribological performance of a novel hybrid nano-lubricant for bronze/AISI 4340 alloy-steel tribopair. The hybrid nano-additive used in the present study helps to improve the lubricity and can sustain under extreme conditions. Initially, friction and wear properties are recorded by varying concentrations of Al2O3 (0.5, 0.8, 1.0, and 1.5 wt. %) and GNP (0.05, 0.1, 0.2, and 0.5 wt. %). Based on the results, an optimum hybrid concentration (OHC) is prepared by adding 0.8 wt. % of Al2O3 and 0.2 wt. % of GNP which resulted in 83.84% and 79.75% reductions in coefficient of friction (COF) in comparison to optimum Al2O3-based and GNP-based lubricants, respectively. However, the wear volume (WV) for OHC lubricant indicated 98.28% and 75% reduction in comparison to the above-mentioned lubricants, correspondingly. Extreme pressure (EP) tests were carried out and OHC lubricant reported improved weld point for hybrid nano additive-based lubricant. [ABSTRACT FROM AUTHOR]