Lubrication Technology Research Articles

Lubricant property evaluation of electrical conductive rice bran oil‐based lubricant with dioctyl ammonium oleate ionic liquid as an additive

AbstractThe growing environmental consciousness and research into green lubricant technology in various industries has drawn a lot of attention to vegetable oils. The major negative aspect of vegetable oil is its poor oxidation stability. Recent research in ionic liquids (ILs) showed its potential as a base fluid and additive for lubricant applications. These are organic salts that dissolve at temperatures below 100°C. Among the potential characteristics of ILs are their non‐volatility, high oxidation stability, non‐flammability, and high conductivity to heat and electricity. The present study synthesized a protic ionic liquid named dioctyl ammonium oleate (DAO). The optimum DAO percentage in rice bran oil (RBO) was then optimized based on the tribological properties. The electrical conductivity and basic lubricant properties, such as physicochemical, oxidation stability, corrosion stability, thermal properties, and extreme pressure capability of the optimized RBO‐DAO blend were evaluated and compared with RBO. The developed RBO‐DAO blend shows the potential to be used as a base fluid for electrical conductive lubricants due to its significantly enhanced electrical conductivity, better oxidation stability, and superior tribological properties. The optimum DAO weight percentage in RBO is 2 wt%. The results show the potential of electrical conductive lubricant developed to enhance the performance of electrical equipment, reduce static electricity in industrial machinery, and prevent lubricant degradation in the presence of electric current. The components of electric vehicles, such as bearings, pads, seals, and gear, also require electrical conductive lubricants to avoid premature failure and electromagnetic interference problems. The developed lubricant can be considered a potential alternative in various industries such as automotive, renewable systems, medical devices, robotics, high‐speed machining, and so forth.

Lubricant Inerting

The recent development of nitrogen concentrators that can filter a stream of almost pure nitrogen from air now makes it practicable to operate closed lubrication systems in an inert atmosphere to limit lubricant oxidation during use—so called “lubricant inerting.” This paper outlines previous work on this topic and indicates the possible benefits of lubricant inerting using nitrogen concentrators. Two important issues are then explored: whether existing lubricant additives can work effectively in a low oxygen environment and the extent to which inerting extends lubricant life in a tribological system. It is found that friction modifiers and extreme pressure additives work as effectively or better in the absence of oxygen compared to their performance in dry air with 21% oxygen (O2). Some ashless phosphorus antiwear additives function better when no oxygen is present, some are less effective in nitrogen than in air, and some appear indifferent to the presence or absence of oxygen. High temperature lubricant testing in a tribometer indicates that degradation, as measured by viscosity increase, Fourier-transform infrared spectroscopy (FTIR), and total acid number (TAN), is almost completely suppressed in nitrogen and is greatly reduced when only 2% O2 is present. The work carried out to date suggests that lubricant inerting has the potential to provide a step-change in lubrication technology, offering greatly extended lubricant lives, enabling much higher operating temperatures, and contributing considerably to sustainability.

Exploration of low-sulfonate lignin electrospinning conditions for the development of new renewable lubricant formulations.

This study explores the preparation of lubricating oleo-dispersions using electrospun nanofibrous mats made from low-sulfonate lignin (LSL) and polycaprolactone (PCL). The rheological and tribological properties of the oleo-dispersions were significantly modulated for the first time through the exploration of LSL/PCL ratio and electrospinning conditions such as applied voltage, distance between the tip and collector, flow rate, ambient humidity, and collector configuration. Adequate uniform ultrathin fibers and Small-amplitude oscillatory shear (SAOS) functions of the oleo-dispersions, with storage modulus values ranging from 102 to 105 Pa at 25 °C, were obtained with a flow rate of 0.5 ml h-1, an applied voltage of 15 kV, relative humidity 45% and a static collector. The LSL/PCL ratio directly affected the mechanical properties of the membranes, influencing stiffness and wear resistance. Higher PCL content enhanced membrane stiffness, reflected in increased SAOS values, but also led to higher friction coefficients (from 0.11 to 0.18) and more pronounced wear traces (measured by wear diameter: 440 to 860 μm). These interactions underscore the complex relationship between micro- and/or nano-structures and tribological performance. This study establishes a clear link between electrospinning conditions and the performance of oleo-dispersions, offering a versatile platform for the development of customizable, renewable lubricants. These findings contribute to the advancement of sustainable lubrication technologies, demonstrating the potential of tailor-made oleo-dispersions as alternatives to traditional lubricants.

Injection Of air control of propeller performance

With the rise of bubble lubrication technology in transport ships, the interaction between propellers and bubble flow has become increasingly important. On the basis of solving the Reynolds averaged equation and the volume fraction equation, a numerical model of the propeller in a water air mixed fluid was established using the sliding mesh technique. Based on verifying the numerical calculation model of the semi-immersed propeller, uncertainty analysis was conducted on the KP505 propeller flow numerical model, and the open water performance of the propeller was calculated to be affected by the injection position and injection volume. A linear model was established to describe the relationship between the open water performance of the propeller at the axis and the injection rate. The performance surface model was used to describe the effect of the air injection position moving towards the blade tip on open water performance at different air injection rates. The strength and dissipation of the tip vortex and hub vortex of propeller are affected by the radial air injection position. Air injection at the axis causes the hub vortex to expand and connects the tip vortex to form a vortex ring in the far field. The air injection position moves towards the blade tip, and the vortex system at the blade tip accelerates and rapidly dissipates.

Evaluation of Wear Resistance of a Modified Radial Bearing Design Taking into Account Compressibility and Viscosity of the Lubricant

Introduction. The challenge problem of the quality of lubricants has led to both large-scale and narrow-focused theoretical and applied studies that relate to the operational properties of lubricants. In particular, the authors of the publications are interested in the interaction of bearing and lubrication, since numerous types of machinery and equipment contain these elements. In the literature, the composites used to strengthen the bearing surface are compared, the most effective compositions are determined, and the advantages and disadvantages of the components are analyzed. Mathematical models have been proposed and tested for some of the processes of the interaction under consideration, and acceptable adequacy has been proved for some of them. However, the improvement of such solutions requires taking into account the specifics of the tribosystem. This issue has been poorly worked out, and the presented article is intended to fill this gap. When evaluating the wear resistance of a radial bearing, the compressibility of a high viscosity lubricant is taken into account.Materials and Methods. The study was based on the tribocontact scheme, which included the radius of the polymer-coated shaft, the radius of the bearing sleeve, the height of the lubrication groove, and the thickness of the lubricating layer. To create new mathematical models that took into account the compressibility of the lubricant, the authors used three equations: motion of the liquid lubricant, continuity, and state. To verify the model, the results of calculations and laboratory tests were compared. In the experiments, a bearing with a groove to preserve lubrication was used. Its rotation speed, loads and temperature conditions were changed. Friction was measured using traditional methods and modern instruments.Results. The bearing design was modified to take into account an additional factor — the compressibility of the lubricant. The new model predicted the bearing capacity of the part by 8–10% more accurately, and the coefficient of friction — by 7–9%. Fluctuations in the coefficient of friction up to 45 MPa (equivalent to a five-fold increase in load) were detected and explained. This was due to dynamic changes in the surface contact conditions and the effects of external parameters. Optimal applications of antifriction coatings based on hybrid composite materials were determined. The possibilities of practical use of calculation models of a journal bearing were expanded. Its critically important operational characteristics were evaluated in practice.Discussion and Conclusion. The scientific research results described in this article make it possible to establish the performance characteristics of the bearing at the design stage. The significant potential of this approach has been identified in terms of increasing the reliability and durability of the studied part, and this seems to be an important step in the development of bearing and lubricant technologies. In the future, the authors intend to study such factors as temperature conditions, dynamic loads, and interaction with various lubricants. This will allow us to improve bearing designs and expand their application areas.

Tribology in Germany: Latest Research and Development

Sixty-five years ago, in November 1959, the “Gesellschaft für Schmiertechnik” (GST, Society for Lubrication Technology), the predecessor organization of today’s German Society for Tribology, was founded in the form of a non-profit technical scientific association [...]

Effect of hydrostatic thrust bearing oil pad structure on performance

Background: The hydrostatic thrust bearing is a liquid lubrication technology based on the principle of hydrostatic pressure, characterized by high load-carrying capacity, low friction, and long lifespan. It has been widely applied in precision machinery and the spindles of high-speed, high-precision equipment. The oil pad of the hydrostatic thrust bearing is a crucial component, and its geometric structure significantly influences the bearing performance. During operation, the oil film of the hydrostatic thrust bearing is subjected to high loads and temperatures. If the oil film does not have sufficient strength, it can affect the normal operation of the bearing, leading to accidents. The oil pad structure is a key factor affecting the strength of the oil film. Therefore, the rational design of the oil pad structure is essential to ensure the performance of the hydrostatic bearing and prolong its service life. Objective: This study aimed to summarize the impact of different oil pad structures on the performance of hydrostatic thrust bearings, providing a basis for the future development of hydrostatic thrust bearings. Method: A search for journals, patents, conferences, and papers related to hydrostatic thrust bearings was conducted, and the impact of oil pad structures on hydrostatic thrust bearings was summarized and analyzed. Results: Based on the research findings of numerous scholars, this study summarizes the impact of oil pad structures on the performance of hydrostatic thrust bearings. It describes how the oil pad shape, oil pocket shape, oil pocket depth, and microtextures affect the overall performance of thrust bearings. The research methods employed are analyzed, and a concluding summary is provided regarding the influence of bearing oil pad geometric structures on bearing performance. Conclusion: This paper provides guidance for the design and optimization of the oil pad in hydrostatic thrust bearings. Finally, it outlines the future development trends of the oil pad in hydrostatic thrust bearings and provides prospects for future development trends and key areas of focus for hydrostatic thrust bearings.

Nanoparticle enhanced biolubricants: a study on thermophysical properties

This paper addresses the effect of CuO nanoparticle suspension on the physical and thermal properties of Pongamia pinnata oil and 20W50 motor oil. The obtained nanolubricants with CuO nanoparticles at concentrations of 0.01%, 0.02%, and 0.05% w/v were comprehensively tested for stability, viscosity, density, thermal conductivity, and specific heat capacity. The detailed studies on zeta potential reported that the nanolubricants of 20W50 motor oil were stable at 0.02%, whereas Pongamia pinnata oil established maximum stability at 0.01%. Viscosity studies at different temperatures revealed that viscosity decreases with an increase in temperature for both oils. However, it was noted that 20W50 motor oil was more viscous compared to Pongamia pinnata oil at all temperatures. From the results, it was witnessed that the incorporation of CuO nanoparticles showed an enhancement in thermal conductivity that was marked for Pongamia oil at higher temperatures but reduced specific heat capacity in both oils. The comparative study of the thermal and physical properties of a bio-based oil, Pongamia pinnata, with that of 20W50 commercial motor oil, infused with CuO nanoparticles, has not been reported so far. The detailed properties of nanolubricants regarding the different nanoparticle concentrations studied, along with the examination of Pongamia pinnata oil as an eco-friendly alternative to conventionally used motor oil, open new possibilities for bio-based nanolubricants. Besides, the performance for specific industrial applications, especially high-load machinery and systems under moderate temperatures, brings this work under a highly relevant framework for green lubrication technologies.

Research on surface roughness of high-speed milling 7075-T6 aluminum alloy using nanofluid/ultrasonic atomization minimal quantity lubrication system.

This study employed a self-developed nanofluid/ultrasonic atomization minimal quantity lubrication system. The use of ultrasonic cavitation can effectively improve the accumulation of nanofluids via van der Waals force bonding and enhance their efficiency. This system is a high-speed milling manufacturing innovation in lubrication technology. Two types of nanoparticles (multiwalled carbon nanotubes and MoS2 nanoparticles) were used to facilitate the mixing of nanofluids and their lubrication in the high-speed milling of 7075-T6 aluminum alloy. The surface roughness of each group of experimental results was used as the characteristic index. The surface roughness obtained from the optimization of the experimental results was 0.51 μm, while the worst group, which was based on the original orthogonal table, had a surface roughness of 1.05 μm, demonstrating an improvement of 51.43% in the quality characteristics. Results of comparative experiments demonstrated that using a nanofluid mixed with multiwalled carbon nanotubes and MoS2 nanoparticles exerted better effects on surface roughness, tool wear, and workpiece burrs than using only nanofluids with single nanoparticles. This finding can be attributed to the mixed nanofluid, which simultaneously possesses the good grinding capability of MoS2 and the excellent heat transfer property of multiwalled carbon nanotubes.

Mucus-inspired biomass-derived carbon dots-based solvent-free nanofluid with polyelectrolytes networks toward excellent green lubrication

Mucus-inspired biomass-derived carbon dots-based solvent-free nanofluid with polyelectrolytes networks toward excellent green lubrication

A general strategy for developing eco-friendly, harsh condition adaptive, and friction tunable supramolecular gel lubricants via hydrogen bonding interaction

A general strategy for developing eco-friendly, harsh condition adaptive, and friction tunable supramolecular gel lubricants via hydrogen bonding interaction

Study on Traction Characteristics of Point Contact State under Oil–Air Lubrication

Oil–air lubrication technology is commonly utilized in the lubrication design of traditional components to reduce friction between contact pairs. This study focuses on testing the point-contact friction pairs of two quantitative valves using a self-made oil–air lubrication traction force machine with a G95Cr18 disk and ball as the friction pairs. The test data are analyzed using a four-parameter exponential model. Additionally, a calculation model of the oil–air lubrication flow field is established, defining boundary conditions and conducting flow field simulation analysis. The results of the ball and disk test show that the traction coefficient increases with load and decreases with entrainment speed. Furthermore, when the air-speed is 12 m/s, the traction coefficient is lower for the oil supply of 6 mL/min than for the oil supply of 1.5 mL/min. According to CFD analysis, the volume fraction of the oil phase in the contact area increases with the increase of entrainment speed when the slip–roll ratio is 0.1. The theoretical values from the four-parameter exponential model align well with the experimental results, and the fitting accuracy is higher than 0.95.

K-means clustering optimization of various quantum dots and nanoparticles-added biofuels for engine performance, emission, vibration, and noise characteristics

K-means clustering optimization of various quantum dots and nanoparticles-added biofuels for engine performance, emission, vibration, and noise characteristics

Research on Tool Wear and Machining Characteristics of TC6 Titanium Alloy with Cryogenic Minimum Quantity Lubrication (CMQL) Technology

Titanium alloys are crucial in precision manufacturing due to their exceptional properties, but traditional machining methods lead to tool wear, deformation, and high costs. Conventional cooling fluids reduce heat but cause environmental issues, necessitating more sustainable solutions. Cryogenic Minimum Quantity Lubrication (CMQL) technology, using liquid nitrogen or carbon dioxide with minimal amounts of cutting fluid, offers an eco-friendly alternative that reduces machining temperatures and friction. This study tested the TC6 titanium alloy under conventional and CMQL conditions, focusing on tool wear, surface quality, and machining efficiency. Results showed that CMQL significantly decreased tool wear and surface roughness, with a 42% reduction in surface roughness during drilling and a 20–30% efficiency increase. The findings highlight CMQL’s potential to improve machining quality and efficiency while promoting environmentally friendly practices in the industry.

Superlubricity in solid lubricated sliding and rolling contacts

Superlubricity in solid lubricated sliding and rolling contacts

Optimization and influence of oil supply parameters on oil capture characteristics of radial oil scoop for high-speed bearings

Optimization and influence of oil supply parameters on oil capture characteristics of radial oil scoop for high-speed bearings

An oil‐on‐water minimum quantity lubrication technology for high‐quality grinding of carbon fiber reinforced thermoplastic composites

AbstractCarbon fiber reinforced thermoplastic (CFRTP) composites, known for their excellent mechanical properties and environmental sustainability, are highly sought‐after in aerospace, energy, and many other fields. Grinding could be used to realize the high‐accuracy and low‐damage machining of CFRTP components. However, due to the temperature sensitivity and water absorption of CFRTP, dry and flood lubrication grinding could cause thermal damage and hygrothermal aging, respectively. In addition, these methods could lead to dust and excessive cutting fluids harmful to the environment. Addressing these bottlenecks, this study is the first to propose using oil‐on‐water minimum quantity lubrication (OoW‐MQL) to grind CFRTP. Experiments including various lubricating conditions and grinding parameters were performed to investigate the grinding performance. Experimental results showed that OoW‐MQL with the oil–water proportion of 1:1 outperformed the other lubricating conditions, achieving the best surface quality with the lowest grinding forces and temperatures. The optimal oil–water proportion remained almost unchanged under different grinding parameters. Furthermore, importance analysis using the extreme gradient boosting (XGBoost) algorithm demonstrated that oil–water proportion was the most critical factor affecting surface roughness. This study proves the feasibility of OoW‐MQL and provides technical guidance for high‐quality grinding of CFRTP.Highlights Oil‐on‐water minimum quantity lubrication (OoW‐MQL) was proposed to grind carbon fiber reinforced thermoplastic (CFRTP) composites. The experimental results of grinding forces, grinding temperatures, surface roughness and surface morphologies were analyzed, which proved that OoW‐MQL with oil–water proportion (1,1) had outstanding lubricating and cooling capability. The effect of grinding parameters on the optimal oil–water proportion was proved to be negligible through comparative tests under grinding parameters of high force and high temperature. Quantitative analysis using the extreme gradient boosting (XGBoost) algorithm identified the oil–water proportion as the most critical factor influencing surface roughness.

Magnetohydrodynamic Darcy-Forchheimer flow of non-Newtonian second-grade hybrid nanofluid bounded by double-revolving disks with variable thermal conductivity: Entropy generation analysis

Magnetohydrodynamic Darcy-Forchheimer flow of non-Newtonian second-grade hybrid nanofluid bounded by double-revolving disks with variable thermal conductivity: Entropy generation analysis

The development status and future trends of lubricant additives technology: Based on patents analysis.

In order to reveal the current status and future trends of lubricant additives, this study analyzes the structured and unstructured data of 77701 lubricant additive patents recorded by Patsnap. The results show that China is the country with the largest number of patents in this field, and the United States is the main exporting country of international technology flow; the current research and development of lubricant additives is dominated by multifunctional composite additives; environmentally friendly additive compositions are the current research hotspot; and more environmentally friendly and economically degradable additives have more development potential in the future. Overall, this study provides a comprehensive understanding of the research and application of lubricant additives and contributes to the future development of the lubricant industry.

Preparation and Tribological Behaviors of Sulfur- and Phosphorus-Free Organic Friction Modifier of Amide–Ester Type

With the increasingly demanding engine conditions and the implementation of “double carbon” policies, the demand for high-quality lubricants that are cost-effective and environmentally friendly is increasing. Additives, especially high-performance friction modifiers, play an important role in boosting lubricant efficiency and fuel economy, so their developments are at the forefront of lubrication technologies. In this study, 1,3-dioleoamide-2-propyloleate (DOAPO), which incorporates polar amide, ester, and nonpolar alkyl chains, was synthesized from 1,3-diamino-2-propanol to give an eco-friendly organic friction modifier. Nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HR-MS), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA) were used to characterize the structure and thermal stability of DOAPO. Meanwhile, the storage stability and tribological behaviors of DOAPO in synthetic base oil were studied and compared with a commercial oleamide. The results show that DOAPO has better thermal stability and better storage stability in synthetic base oil. Additionally, 0.5 wt.% of DOAPO could shorten the running-in period and reduce the average friction coefficient (ave. COF) and wear scar diameter (ave. WSD) by 8.2% and 16.2%, respectively. The worn surface analysis and theoretical calculation results show that the ester bond in DOAPO breaks preferentially during friction, which can reduce the interfacial shear force and easily react with metal surfaces to form iron oxide films, thus demonstrating a better friction-reducing and anti-wear performance.