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The purpose of this paper is to improve the antifriction and antiabrasive behavior of the used oil through the addition of a lubricant.

The author selected 85W-90 used oil with three kinds of 4,758, 10,507 and 16,223 km mileages, which may represent run-in wear period, steady-state wear period and rapid wear for used oil, respectively. Nano copper, molybdenum dithiocarbamate (MoDTC) and copper dioctyl dithiocarbamate (CuDTC) of lubricant additive are added to the used oil to improve its antifriction performances and service life. The influence of lubricant additive on the tribological properties of used oil is investigated by the friction tests.

An abnormal phenomenon has been observed by the friction test under high mileage used oil with CuDTC in presence of MoDTC lubrication, and superlow friction coefficient of 0.04 has been achieved after a running-in period for the first time. It is found that CuDTC additive is beneficial to improve greatly the antifriction behavior of used oil, especially when MoDTC is present. The results indicate that the dissoluble of CuDTC and the tribochemical reaction of MoDTC play an important role in superlow friction of high mileage used oil. Moreover, the superlow friction is also closely related to the viscosity of used oil.

The possible mechanism of superlow friction is attributed to the additive thinning effect and the synergistic effect of the dissoluble of CuDTC and the tribochemical reaction of MoDTC binary lubricant additives in high mileage used oil. This work will extend the application of CuDTC additive widely and explore a new method to the reutilization and the life extension of used lubricating oil.

The purpose of this paper is to investigate the effects of parallel texturing coating on antifriction mechanism of lubricating wear-resistant coating.

A KF301/WS2 lubricating wear-resisting coating was prepared on matrix material GCr15 by applying supersonic plasma spraying technology. On the basis of this sample, the KF301/WS2 modified coating with parallel pit-type texture was prepared by laser re-melting technology and a surface texturing technique. Their friction and wear behaviors were evaluated under ambient temperature, and the antifriction mechanism of two kinds of coatings were discussed.

Results showed that parallel texture has a certain impact on the tribological properties of the coating. When friction and wear reach stable state, the value of the friction coefficient of conventional coating was 0.115, while that of parallel texturing coating was 0.09, the latter decreased by 21 per cent. When the friction and wear time was up to 4 hours, the wear loss of the conventional coating was 0.29 mg, while that of the parallel texturing coating was 0.13 mg, the latter decreased by 55 per cent.

The tribological properties of parallel texturing coating were higher than conventional coating. That is because the change of three-body layer reduces the friction coefficient and the abrasive particles were collected by parallel texture, reducing the effects of debris.

The purpose of this paper is to study the antifriction, antiwear and tribolayer formation properties of the trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate ionic liquid (IL) as additive at 1 wt.% in two base oils and their mixtures, comparing the results with those of a commercial oil.

The mixture of the base oils used in the formulation of the commercial oil SAE 0W20 plus the IL was tested under rolling/sliding and reciprocating conditions to determine the so-called Stribeck curve, the tribolayer formation and the antifriction and antiwear behaviors.

The use of this IL as additive in these oils does not change their viscosity; improves the antifriction and antiwear properties of the base oils, making equal or outperforming these properties of the SAE 0W20; and the thickness and formation rate of the tribolayer resulting from the IL-surface interaction is highly dependent on the type of base oil and influence on the friction and wear results.

The use of this IL allows to replace partial or totally commercial antifriction and antiwear additives.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0179/

This study aims to improve the tribological properties of hydrodynamic journal bearing via surface texture, as well as the wear and antifriction mechanisms of textured bearing were represented. It provides a design direction for solving the tribological problem of rotor-bearing system.

In this paper, the variation of surface texture parameters (e.g. texture diameter, d; area density, sp; and depth, hp) were analyzed based on finite difference method. The optimal surface texture parameters were obtained by designing orthogonal experiments, and the relationship between friction and wear properties and microstructure was studied via combining electron probe microanalyzer, scanning electron microscope, X-ray diffractometer and friction and wear testing machine.

Dimensionless film pressure P increased as the d increased, whereas P first increased and then decreased as the sp and hp increased, and the maximum P was got as sp = 15% and hp = 25 µm, respectively. The friction coefficient of textured surface with suitable parameters was effectively reduced and the textured surface with the best antifriction effect was 5#. Orthogonal experimental design analysis showed that the influence order of factors on friction coefficient was as follows: sp > sp × d > d > d × hp > hp > sp × hp and the friction coefficient first decreased and then increased as the sp, d and hp increased. In addition, the friction and wear mechanism of textured bearing were three body friction and abrasive wear as the matrix structure and hard phase were a single β phase and Mn5Si3, respectively. While the antifriction mechanism of textured surface was able to store abrasive particles and secondary hydrodynamic lubrication was formed.

The sample with reasonable texture parameter design can effectively reduce friction and wear of hydrodynamic journal bearing without reducing the service life, which can provide a reference for improving the lubrication performance and mechanical efficiency of rotor-bearing system.

OVER the years lithium soap greases have earned a reputation of providing excellent service under a wide variety of operating conditions. Since their introduction in the early 1950s, lithium soap greases have served the market well, being especially suitable for both automotive and industrial multipurpose applications. Their performance has enabled them to grow in commercial importance to the point where they now account for over half the grease volume manufactured in the United States.

Carbon steel has a high application rate in modern industry, but this type of steel has the defect of high wear. This study aims to improve the surface friction and wear performance of carbon steel under such working conditions.

In this study, a dry film lubricant based on graphite powder was prepared by the ultrasonic dispersion method, and deposited on the surface of carbon steel specimens by the simple pressure spraying technology. At the same time, molybdenum disulfide and polytetrafluoroethylene dry film lubricants were developed by the same method, and the comparative experimental study on friction and wear was carried out in the end-face friction tester.

The results show that the deposition effect of graphite and molybdenum disulfide dry film lubricants on the surface of carbon steel is obviously better than that of polytetrafluoroethylene dry film lubricant. Compared with molybdenum disulfide and polytetrafluoroethylene dry film lubricant, graphite dry film lubricant has the best friction and wear performance on the surface of carbon steel. The working life of carbon steel specimens sprayed with graphite dry film lubricant decreases with the increase of pressure load and rotation speed. The combination of load and sliding speed will accelerate the transition of the coating to a stable direction. In addition, the micro lubricant particles formed in the wear process will form particle flow lubrication, and the appropriate addition of particle powder of the same material will also prolong the normal antifriction time of the lubricant.

These findings developed a dry film lubricant that can effectively improve the friction and wear properties of carbon steel surface.

This paper aims to fabricate a FeS/Cu-Bi copper-based lead-free bearing material to maintain good friction-reducing and anti-adhesive properties under boundary lubrication conditions.

The materials were fabricated by mechanical alloying and powder metallurgy and tested under dry friction conditions using HDM-20 wear tester.

The results show that mechanical alloying can improve the antifriction and wear resistance of the materials. The 6 per cent FeS and 6 per cent Bi in the copper-based bearing materials fabricated by mechanical alloying have a better synergism which contributes to the friction and wear properties of copper matrix.

This new approach solves the problems of Bi and FeS mutual segmentation, mutual agglomeration and poor interface bonding.

The role that lubricating oils play is, first of all, to reduce energy loss and keep the wear and seizure to a minimum, or, in a broader sense, to improve the friction characteristics. Resistance to deterioration and prevention of rust development on metals are demanded as secondary functions. The time during which lubricating oil retains its ability to prevent any possible damage to a body in motion should be considered as its lifetime. Many functions that are provided by base oil alone are insufficient; therefore, special additives are dissolved in them. The additives for lubricating oils are of many types, and their functions are diverse and many. Those additives that are used with the purpose of improving friction characteristics are generally called oiliness improvers or friction modifiers. In this study, the protective additive's layers formed on rubbed surfaces of pins, plates and discs were investigated using pin‐on‐disc and reciprocating pin‐on‐plate test rigs. Wear tracks were examined using optical and electron microscopy with X‐ray diffraction analysis.

The purpose of this study is to synthesise and characterise surface-capped molybdenum sulphide (SCMS) nanoparticles using the solvothermal method and to investigate their tribological behaviour towards friction improver and wear reduction for bio-based lubricant oil additives.

The design of the experiment was to use freshly prepared molybdenum (II) acetate, thioacetamide, fatty acid and hexane as the solvent inside an autoclave vessel which is heated at high temperature and pressure. Various types of fatty acids were used as the capping agent, such as caproic, lauric, stearic and oleic acid. The SCMS nanoparticles formed were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffractometry, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermal gravimetric analysis. These nanoadditives were then blended into pentaerythrityl tetracaprylate/caprate ester at 0.05 Wt.% concentration. The formulated bio-based lubricant oil samples were tested for viscosity, viscosity index (VI) and density based on standard method ASTM D445 and ASTM D2270. A four-ball test was carried out for determination of coefficient of friction and wear scar diameter. The wear scar formed on the surface of the ball bearing was analysed using scanning electron microscopy.

The characterisation results showed that SCMS nanoparticles were successfully formed with amorphous ball-like structure, and the presence of the capping layer surrounding the nanoparticles was confirmed. Then, the formulated bio-based lubricant oil with addition of nanoadditives displays improved tribological properties in term of VI, antifriction and wear reduction.

This research provides a synthesis method of producing SCMS nanoparticles using the organomolybdenum complex as the chemical precursor through the solvothermal reaction approach. Besides that, it also gives an alternative antifriction and antiwear nanoadditive for formulation of the bio-based lubricant oil.

This study aims to investigate the synergistic friction reduction and antiwear effects of lyophilized graphene loading nano-copper (RGO/Cu) as lubricating oil additives, compared with graphene.

The friction performance of freeze-drying graphene (RGO) and RGO/Cu particles was investigated at different addition concentrations and under different conditions.

Graphene plays a synergistic friction reduction and antiwear effect because of its large specific surface area, surface folds and loading capacity on the nanoparticles. The results showed that the average friction coefficients of RGO and RGO/Cu particles were 22.9% and 6.1% lower than that of base oil and RGO oil, respectively. In addition, the widths of wear scars were 62.3% and 55.3% lower than those of RGO/Cu particles, respectively.

The RGO single agent is suitable for medium-load and high-speed conditions, while the RGO/Cu particles can perform better in the conditions of heavy load and high speed.