Investigation of the Tribological Behavior of Mineral Lubricant Using Copper Oxide Nano Additives

Photothermal COFs with donor-acceptor structure for friction reduction and antiwear

For the first time, a novel donor-acceptor structured COF with excellent photothermal conversion and mono-dispersity in various oils without any further modification is reported; it realized responsive friction reduction, excellent antiwear and long-time lubrication.

Investigation of Thermal and Tribological Behaviour of Oil Dispersed Oleic Acid-Functionalized CuO Nano-Particles in Gear Oil Nano-Lubricants

Nano-fluids are the new class of engineered fluids developed by dispersing nano-additives in base lubricants to enhance the thermal and tribological properties. In the present study, the CuO nano-fluids were prepared by dispersing oleic acid (OA) functionalized nano-particles in gear oil lubricants and have been tested for their performance evaluation in terms of friction, wear, and extreme pressure behavior. However, the effect of thermal conductivity on tribological performance at higher load was also investigated. The two-step method was used to formulate the CuO nano-fluids and OA was used as a surface functionalizing agent. Analytical techniques like FTIR, XRD, DLS, SEM, and EDX were used to investigate the characteristic properties of CuO nanoparticles. The sedimentation method and Induced Couple Plasma (ICP) technique were used to determine the dispersion stability of nano-fluids over 3 months. Further, KD2 Pro thermal conductivity analyzer was used to examine the thermal conductivity of nano-fluids. The findings reveal that the functionalized CuO nano-particles significantly improved the tribological properties of gear oil lubricants. Further, the enhancement in thermal conductivity reduced the contact temperature at a higher load and prevents seizure. The comparative assessments confirmed that CuO nanoparticles can be used as lubricant additives for gear oil lubricants.

Contact Characteristics at Interface in Three-Body Contact Conditions with Rough Surfaces and Foreign Particles

Nanoparticles as lubricant additives under a certain average diameter and concentration may reduce wear, friction and scuffing damage. However, atmospheric dust particles affect not only human health but also the efficiency of components, and even cause component failures. Therefore, the contact characteristics at interfaces with foreign particles require careful investigation. In this work, a 3-body microcontact mechanics concept is used to analyze the effects of wear debris and foreign particles on real contact area, contact mode, asperity deformation type and separation at interface. The results show that the relationship profile between dimensionless real contact area (At*) and dimensionless normal contact load (Ft*) is wedge-shaped in a 3-body contact interface. Using surface-to-surface 2-body contact area as upper bound and surface-to-particle 3-body contact as lower bound, the 3-body hybrid contact situation is in between upper and lower bounds. As the dimensionless normal contact load increases, At* increases gradually as well. The order of contact mode is p-s contact, hybrid contact and then s-s contact. If the 3-body contact interface is in hybrid contact mode, the decrease in the hardness and average third body diameter will cause the At* to increase significantly at the same Ft*. Conversely, the separation and real contact area ratio of plastic deformation decrease gradually. The turning point of contact area (TPCA) occurs when the contact mode is within hybrid contact mode and the ratio of average third body diameter to the composite equivalent surface RMS roughness is about 50–70% for foreign particles and wear debris. When the Ft* is slightly larger than Ftpca*, the third body and surface share the total interface load approximately equally which will help reduce the real contact pressure and plastic contact area to improve surface performance.

A review of advances in tribology in 2020–2021

Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.

Tribological Behavior of Ionic Liquid with Nanoparticles

This research aims to formulate a new lubricant containing oxide nanoparticles for enhancing anti-wear ability and reducing friction. Different concentrations of copper oxide (CuO) and zinc oxide (ZnO) nanoparticles were separately added to an ionic liquid, methyltrioctylammonium bis(trifluoromethylsulfonyl)imide [N1888] [NTf2], to formulate the tested lubricants. The tribological properties of the lubricants were tested by performing ball-on-disc wear tests on a tribotester (MTM, PCS Instruments). The results show that both the CuO and ZnO nanoparticles can increase the friction reduction ability of the ionic liquid when used as a neat lubricant. The anti-wear characteristic of the ionic liquid is increased by adding ZnO nanoparticles but decreased by adding CuO nanoparticles. The best tribological performance observed for the concentration of 0.2 wt% ZnO, with the wear scar diameter is reduced by 32% compared to the pure ionic liquid. The results of SEM/EDX analysis on the worm morphologies show different lubrication mechanisms of the nanoparticles in the [N1888] [NTf2], which are tribo-sintering for CuO nanoparticles, and third body with pure rolling effect for ZnO nanoparticles.

Recent Advances in Preparation and Testing Methods of Engine-Based Nanolubricants: A State-of-the-Art Review

Reducing power losses in engines is considered a key parameter of their efficiency improvement. Nanotechnology, as an interface technology, is considered one of the most promising strategies for this purpose. As a consumable liquid, researchers have studied nanolubricants through the last decade as potential engine oil. Nanolubricants were shown to cause a considerable reduction in the engine frictional and thermal losses, and fuel consumption as well. Despite that, numerous drawbacks regarding the quality of the processed nanolubricants were discerned. This includes the dispersion stability of these fluids and the lack of actual engine experiments. It has been shown that the selection criteria of nanoparticles to be used as lubricant additives for internal combustion engines is considered a complex process. Many factors have to be considered to investigate and follow up with their characteristics. The selection methodology includes tribological and rheological behaviours, thermal stability, dispersion stability, as well as engine performance. Through the last decade, studies on nanolubricants related to internal combustion engines focused only on one to three of these factors, with little concern towards the other factors that would have a considerable effect on their final behaviour. In this review study, recent works concerning nanolubricants are discussed and summarized. A complete image of the designing parameters for this approach is presented, to afford an effective product as engine lubricant.