Oil Lubrication Research Articles

Particulates Distribution in the Dynamic Pressure Sliding Bearing under the Oil Lubrication Condition

In the dynamic pressure sliding bearing under the oil lubrication condition, the lubrication oil between the journal and the bearing bush maintains the normal operation of the bearing, which is affected by the complete oil film, the boundary lubrication and the mixed film. With the increase of oil input and journal speed, it is not uniform towards the dynamic pressure distribution inside the sliding bearing. At the same time, cavitation is occurring, causing that particulates fall off the bearing surface, as well as the increase of the improper noises, which reduce the service life of the sliding bearing. The experimental result shows that the wear particles in the oil film are affected by the rotation speed of the shaft journal, the external load of the bearing and the size of the wear particles, so the wear particles in the bearing oil film are concentrated at the working face of the bearing bush and the minimum thickness of the oil film by centrifugal motion. Therefore, the study of the physical and chemical characteristics, which are talked on wear particles in the lubricating oil film of dynamic pressure sliding bearings, will play an important role in the fault diagnosis and condition monitoring of sliding bearings in the mechanical field.

Tribological Behaviour and Lubricating Mechanism of Tire Pyrolysis Oil

The four-ball tester was used in this analysis to demonstrate the lubricity of tire pyrolysis oil (TPO). The tribological performance of the tire pyrolysis oil was compared with diesel fuel (DF) and their blends, DT10 (TPO 10%, Diesel 90%) and DT20 (TPO 20%, Diesel 80%). A scanning electron microscope (SEM) was used to investigate the wear scar. In contrast to diesel fuel, TPO demonstrated better antiwear behaviour in terms of higher load-carrying capacity. DT10, DT20, and TPO’s wear scar diameter (WSD) was 22.35%, 16.01%, and 31.99% smaller than that of diesel at 80 kg load, respectively. The scanning electron microscope micrographs showed that the TPO and DT10 had less wear than their counterparts.

Analysis of the tribological interaction of a polytetrafluoroethylene-lined radial lip oil seal, shaft and lubricant sample

To investigate the tribological interaction and wear mechanisms of polytetrafluoroethylene-lined radial lip oil seals in service, a sleeve, seal and lubricant sample taken off a rotating rig are studied. The test was terminated at 72 h, after severe leakage in the final 15 h of the test. All three components are studied using a coherence scanning interferometer and environmental scanning electron microscopy to investigate wear after testing. Results show a wear band on the aerospace grade case-hardened sleeve, appearing as a ‘polished in’ area by the seal. A study of the filler content of the polytetrafluoroethylene coating uncover glass fibres, calcium carbonate, carbon and graphite layers present, assumed responsible for the wear to the sleeve. The polytetrafluoroethylene coating is a 300 μm coating, distinct from the bulk elastomer. This finding is confirmed after observing this layer on both, the tested and new seal lip. Wear of the seal lip is measured and facilitated by comparison to the identical new seal. Lastly, debris from the seal and sleeve wear are found in the lubricant sample.

Sonication-assisted solvothermal synthesis of noncovalent fluorographene/ceria nanocomposite with excellent extreme-pressure and anti-wear properties

This work aims to improve the dispersion and lubrication properties of fully fluorinated graphene (FG) with little influence on its fluorine content. A simple sonication-assisted solvothermal method was used to improve FG's wear-resistance property and relatively low oil dispersion stability by preparing hierarchical-structured FG/ceria (FG/CeO2) nanocomposite. With the coaction of sonication and solvothermal treatment, the CeO2 nanoparticles are decently distributed over the FG nanosheets, and no noticeable decrease of relative fluorine content is observed after the treatment. The nanocomposite shows excellent synergistic effects in dispersibility and oil lubrication ability. Without influencing FG's original extreme pressure performance, the addition of CeO2 nanoparticles improves FG's oil dispersion stability and significantly enhances FG's anti-wear performance under the extreme working loads.

Tribological behaviors of novel epoxy nanocomposites filled with solvent-free ionic SiO2 nanofluids

A novel nanocomposite was prepared by uniformly dispersing synthesized solvent-free ionic SiO2 nanofluids (NFs) into epoxy resin (EP). Tribological performance of SiO2 NFs/EP composites were investigated when rubbing against bearing steel under base oil lubrication conditions. The results demonstrate that the addition of even low-loading SiO2 NFs greatly improves the tribological performance of EP. It is disclosed that a nanostructured tribofilm grows on the steel surface when sliding against the EP nanocomposite filled with SiO2 NFs. Comprehensive analyses of tribofilms’ nanostructures suggest that tribofilm growth is fed by the molecular species released from the EP nanocomposite. Formation of the load-bearing tribofilm is surmised essential for the enhanced tribological performance of the EP nanocomposite. This work paves a good formulation route for developing high-performance tribo-composites subjected to harsh lubrication conditions.

Technology Upgrades and Reliability Analysis of a Tribometer for Performance Evaluation of Cylinder Piston Rings

The design of existing tribometers mainly focuses on normal contact and lubricant conditions and aims to evaluate the effect of the load, speed, and environmental conditions on the rubbing pair properties. The effect of the contact angle and variable speed on the rubbing pair properties is often not considered. In this study, a multidirectional adjustment tribometer is developed to evaluate the tribological behavior of cylinder liner–piston rings under dry sliding or oil lubrication conditions. The dynamic, specimen clamping, measuring, and control systems are redesigned according to the structural characteristics of the SKODA-SAVIN tribometer and special requirements of research on the net texture effect on tribological properties. Using LabVIEW software, a man–machine interface is designed to achieve converter control, data acquisition, and other functions. A fail-safe analysis is performed through reproducibility, comparability, and sensitivity tests. From the experiments, it is proved that the tester can provide more detailed, abundant, and reliable data for the performance testing and development of cylinder liner–piston ring materials.

Study on hardness and wear resistance of shot peened AA7075-T6 aluminum alloy

AA7075-T6 aluminum alloy samples were shot peened at various shot peening pressures in the range of 10–70 psi to study their mechanical and tribological properties under dry and mineral oil lubrication conditions. The surface roughness of the shot peened AA7075-T6 samples apparently increased with increased shot peening pressure. The best bearing surface was obtained when the shot peening process was carried out at the highest shot peening pressure of 70 psi. It was found that the increased shot peening pressure increased the hardness and decreased the wear of the shot peened samples. The shot peened samples tested under the mineral oil lubrication condition also had lower wear for higher shot peening pressures due to the combined effects of their higher surface wear resistance and better bearing surfaces. The results clearly showed that using the mineral oil lubricant during sliding apparently decreased the wear of the shot peened samples as a result of the lubricating effect of the lubricant. It could be deduced that the tribological properties of the shot peened AA7075-T6 samples under the dry and lubrication conditions were affected by the shot peening pressure.

In-Situ Formed Al3Zr Compounds Reinforced Al Composites and Tribological Application

An Al3Zr-reinforced Al matrix composite using metal powders was fabricated via in-situ synthesis in vacuum; these were subjected to a pin-on-disc wear test with a SUS304 disc specimen under oil lubrication. The elemental mixture of Al and ZrH2 particles was sintered in vacuum for the in-situ-formed Al3Zr. ZrH2 particles were thermally decomposed in the reaction with the Al matrix to form hard Al3Zr intermetallic compounds. The friction coefficient and wear volume values of the Al–Al3Zr composites were significantly lower than those of the pure Al specimen. This is attributed to the uniform dispersion of Al3Zr particles in the Al matrix, which prevented the metallurgical bond from falling and blocked the direct contact between the Al matrix and SUS304 disc.

High temperature solid/liquid lubrication behaviours of DLC films

AbstractThe high temperature solid/liquid lubrication performances of DLC (diamond like carbon) films were investigated by a ball‐on‐disc tribometer under perfluoropolyether (PFPE) oil. The friction and wear behaviours of DLC films sliding against a Si3N4 ball at different friction pairs, sliding speeds and temperatures were evaluated systematically under dry friction. Moreover, tribological properties of DLC films were investigated under PFPE oils lubrication at elevated temperature. The experimental results show that the solid–liquid synergy lubrication is beneficial to improve the tribological properties of the steel‐related friction system and the tribological properties of the friction pair are significantly influenced by lubrication modes under PFPE oil lubrication, especially at high temperature. Tribotests show that the friction system exhibited low friction behaviours under PFPE oil due to the excellent thermal stability of PFPE oil. Coefficient of friction (CoF) of the friction system is as super low as 0.029 under PFPE oil.

Abstracts

New additives are under development to improve wear and tear properties of engine components, fuel efficiency and to reduce carbon emissions from cars and commercial vehicles by reducing friction. To prolong the lifetime and maintain the efficiency of exhaust car emission reduction devices, the modern engine oils must contain low sulphate dash, phosphorus and sulfur. This thesis describes the impact of adding lubricant additives on the visco-elastic and thermo-physical properties of engine oils. The engine oils used in automotive industry are one of the most widely used consumable entities. There has been an ever increasing demand to improve the performance of engine oil lubricants. For that purpose, performance enhancing additives have been added to engine oil lubricants since past few decades. Subsequently, there is an ever increasing need to show the contribution lubricant additives make towards the automotive industry, the consumer and the impact on the environment. Such additives encompass applications for lubrication of passenger car (diesel and gasoline engine) lubricants, truck, coach and bus diesel engine lubricants, heavy duty engine oil etc. The document demonstrates the contribution made by lubricant additives in these applications to the consumer, industry and the environment, through their ability to optimise desirable lubricant properties while suppressing unwanted ones.

Effects of oil retention property for sinusoidal textures on tribological characteristics under scarcity oil supply

Continuous and proper oil lubrication between the friction pair can reduce wear and increase service life of mechanical components. In this paper, the friction experiment and finite element analysis method are combined to study the tribological properties and oil retention mechanism of sinusoidal textured under various width-depth ratios and oil supply. The results indicate that the sinusoidal texture can improve tribological property. ST-3 (the width-to-depth ratio is 1.35) has optimal oil retention property. Compared with untextured specimens (UT), the wear and friction coefficient of ST-3 are reduced by 74% and 7.7%, respectively. Furthermore, the maximum positive pressure is proportional to the non-friction area. This research provides a basis for the optimization design of texture.

A study on improvement of cold flow behaviour and thermal-oxidation stability of Camellia sinensis assamica (tea) oil lubricants as industrial lubricant

In recent years, vegetable oil based bio-lubricant has drawn attention due to its inherent eco-friendly characteristics such as non-toxicity and high biodegradability. Low thermal-oxidation stability and pour point temperatures limit large-scale industrial application of vegetable oil based lubricant. The present work studied improvement of pour point temperature and oxidation stability of Camellia sinensis assamica (tea) seed oil (CSO) with varying weight percentage of Camellia sinensis assamica deoiled cake derived bio-oil. Bio-oil was added with CSO at 5%, 10% and 15% concentration by weight. The results showed improvement of oxidation stability due to presence of alkylated phenols in bio-oil. The oxidation onset temperature was increased from 243.89°C to 274.55°C. The pour point of CSO also improved from initial temperature -4°C to -27°C.

The effect of use of biodiesel B30 from palm oil to degradation of oil lubrication in 1-cylinder diesel engine 4-stroke

New alternative fuels are needed to reduce the fossil fuels. Biodiesel from palm oil is one alternative fuel to replace fossil fuel. This is because Indonesia is the largest producer of palm oil in the world. There are several analyzes that the use of palm oil causes a significant decrease in the viscosity of lubricating oil. A research is carried out to evaluate the effect of B30 biodiesel from palm oil on the degradation of diesel engine lubricating oil. The method used is experiment with testing diesel engines endurance referring to the standards of the Engine Manufacture Association (EMA) to determine differences in lubrication degradation. As a result, B30 biodiesel from palm oil causes greater degradation in lubricating oil than using Dexlite diesel fuel. Biodiesel B30 causes lubricating oil to decrease its viscosity by 46.98%, increase the viscosity index by 7.84%, increase in the flash point, increase in the pour point some 3°C and decrease in the base number by 4.62% and 3.6026% less water content.

Enhancement of tribological behaviour and thermophysical properties of engine oil lubricant by Graphene/Co-Cr nanoparticle additives for preparation of stable nanolubricant

In the current study the tribological properties of Aluminum alloy (Al 25) with moment in time was examined by adding nanoparticles as additives. Nanoparticles exhibit high thermal conductivity, stable viscosity and can be dispersed well in oil. The purpose of this research is to determine the effect of Al2O3, TiO2, Graphene (G), Co-Cr, Ni nanoparticles on lubricity using linear wear testers under reciprocating sliding motion. SEM and EDX characterization techniques are used to study the composition and morphology on worn surfaces. The findings showed that the tribological properties of the substrate lubricant were significantly increased with the addition of nanoparticles. Friction and Wear are reduced with Graphene, Al2O3, TiO2, Ni & Co-Cr nanoparticles as additives for the same load value and can be used as multifunctional additives. Co-Cr at 0.03wt% has provided best performance among the other nanoparticles and can be used as Nano lubricant in the future.

Polysiloxane Nanofilaments Infused with Silicone Oil Prevent Bacterial Adhesion and Suppress Thrombosis on Intranasal Splints.

Like all biofluid-contacting medical devices, intranasal splints are highly prone to bacterial adhesion and clot formation. Despite their widespread use and the numerous complications associated with infected splints, limited success has been achieved in advancing their safety and surface biocompatibility, and, to date, no surface-coating strategy has been proposed to simultaneously enhance the antithrombogenicity and bacterial repellency of intranasal splints. Herein, we report an efficient, highly stable lubricant-infused coating for intranasal splints to render their surfaces antithrombogenic and repellent toward bacterial cells. Lubricant-infused intranasal splints were prepared by creating superhydrophobic polysiloxane nanofilament (PSnF) coatings using surface-initiated polymerization of n-propyltrichlorosilane (n-PTCS) and further infiltrating them with a silicone oil lubricant. Compared with commercially available intranasal splints, lubricant-infused, PSnF-coated splints significantly attenuated plasma and blood clot formation and prevented bacterial adhesion and biofilm formation for up to 7 days, the typical duration for which intranasal splints are kept. We further demonstrated that the performance of our engineered biointerface is independent of the underlying substrate and could be used to enhance the hemocompatibility and repellency properties of other medical implants such as medical-grade catheters.

Oxidative Stability of Vegetal Oil-Based Lubricants.

Lipids are widely distributed in nature and are one of the most important components of natural foods, synthetic compounds, and emulsions. To date, there is a strong social demand in the industrial sector for the use of sustainable products with a minimal environmental impact. Depending on their origin and composition, lipids can be employed as a plausible alternative as biodegradable lubricants in order to reduce the use of conventional mineral oil lubricants and mitigate their environmental impact. This perspective provides an overview of the advantages and constrains of vegetal oils under different lubrication regimes and the tribochemical reactions that can take place. Also, the different factors and pathways that influence their oxidation, the key role of moisture, and the changes of physical properties under pressure and temperature are reviewed. Special emphasis is devoted to the oxidation instability of fatty acids and vegetal oils and the physical and chemical approaches to improve oxidative and thermal stability are described in detail.

The effect of copper oxide nanoparticle additives on the rheological and tribological properties of engine oil

The rheological and tribological properties of 0.5%, 1.0%, 1.5% and 2% CuO nanoparticles by weight blended in engine oil were studied. Surfactants were used to ensure maximum possible dispersion of the nanoparticles in engine oil. Samples were tested for viscosity, stress, torque and shear rate to be compared with data for just engine oil. Characterization of the Copper Oxide nanoparticles was done using an XRD, FTIR, photoluminescence, UV-Vis spectroscopy and Particle Size Analyzer. Overall, nanoparticle additives seem to result in lower viscosity and lower torque. There was also a force of friction and wear test done on a pin-on-disk machine for all blends. The analysis revealed that 1 wt% CuO blend resulted in low wear and force of friction with improved lubricity of oil.

Nanomaterials Derived from a Copper Cinnamate Complex with 4′-Phenyl-2,2′:6′,2″-terpyridine as Antifriction and Anti-Wear Additives for Oil Lubricants

In the present study, a facile and easily accessible method for obtaining copper-containing nanomaterials by thermolysis of copper cinnamate complex with 4′-phenyl-2,2′:6′,2″-terpyridine at 300 °C was developed. The obtained nanomaterials were studied using X-ray diffraction, atomic force microscopy, scanning electron microscopy and energy dispersive analysis. Analysis of copper-containing nanomaterials as additives to lubricant (liquid paraffin) was carried out from the point of view of their tribological behavior using pin-on-disc and four ball friction machines. At optimum concentration of nanomaterials, the friction coefficient is the lowest. The mechanism of friction in the presence of the studied lubricant compositions is discussed.

Self-lubricating behavior of VN coating catalyzed by solute Ag atom under dry friction and oil lubrication

The development of hard-yet-tough ceramic coatings with self-lubricating behavior is an urgent technological requirement to reduce mechanical friction losses and energy consumption. However, traditional ceramics possessing the limited self-lubricating ability and poor toughness have limited their practical applications. To tackle the above-mentioned problems, we modified ceramic material vanadium nitride (VN) to prepare the catalytically active V-Ag-N solid solution coating by magnetron sputtering and realized high hardness, high toughness, and excellent self-lubricating performance under dry friction and oil lubrication conditions. Through detailed experimental investigations, we explain the enhanced mechanism of both hardness and toughness because of solute Ag; moreover, the solute Ag can trigger the appearance of lubricating silver vanadate phase in dry friction and result in a low coefficient of friction. Besides, it was confirmed that the solute Ag atom would induce effectively catalytic ability for in situ formation of self-lubricating onion-like-carbon structures (OLCs) scrolls from base oil at the sliding interface. The novel strategy would be to open a window for more efficiently catalyzing the in situ formation of silver vanadate and OLCs scrolls activated by solute Ag atoms and more significantly improving the hardness and toughness, thereby further improving self-lubricating behavior under dry friction and oil lubrication conditions.

INVESTIGATIONS ON WEAR AND FRICTION IN THE SI ENGINE VALVETRAIN

The engine valvetrain system operating under conditions of insufficient oil lubrication, caused by incorrect installation of the gasket between the block and the head, was tested. The aim of the analysis was to determine the wear intensity and resistance to motion in camshaft bearings. A model was developed that includes a camshaft, bearings, tappet-valve-spring subassemblies and a part of the lubrication system. It was used to determine the bearing loads and the amount of oil supplied. The volumetric wear of the camshaft journals and bearing covers was measured. For the estimated engine run, the wear rate and resistance to motion were compared for the cases of the engine with correct and incorrect lubrication.