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This paper aims to solve the problems molybdenum disulfide (MoS₂) nanosheets suffer from inadequate dispersion stability and form a weak lubricating film on the friction surface, which severely limits their application as lubricant additives.

MoS₂/C₆₀ nanocomposites were prepared by synthesizing molybdenum disulfide (MoS₂) nanosheets on the surface of hydrochloric acid-activated fullerenes (C₆₀) by in situ hydrothermal method. The composition, structure and morphology of MoS₂/C₆₀ nanocomposites were characterized. Through the high-frequency reciprocating tribology test, its potential as a lubricant additive was evaluated.

MoS₂/C₆₀ nanocomposites that were prepared showed good dispersion in dioctyl sebacate (DOS). When 0.5 Wt.% MoS₂/C₆₀ was added, the friction reduction performance and wear resistance improved by 54.5% and 62.7%, respectively.

MoS₂/C₆₀ composite nanoparticles were prepared by in-situ formation of MoS₂ nanosheets on the surface of C₆₀ activated by HCl through hydrothermal method and were used as potential lubricating oil additives.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2023-0321/

This paper aims to study the upgradation of the lubricating performance of the renewable base oil , and to study the tribological behavior of graphene oxide (GO) sheets used as lubricating additives in bio-oil for iron/steel contact.

A multifunctional end-face tribometer was used to characterize the friction coefficient and wear loss of the tribosystem under different lubricants.

The experimental results show that GO sheets with small size benefit lubricating effects and the optimal concentration of GO sheets in bio-oil is 0.4-0.6 per cent, which can form a complete lubricating film on the frictional interfaces and obtain a low friction coefficient and wear loss. Higher concentration of GO sheets can result in a significant aggregation of the sheets, reducing the content of the lubricating components in the bio-oil, which results in the increase in friction and wear; at this stage, the main wear pattern was ascribed to adhesive wear.

These results show a promising prospect of improving the tribological performance of renewable base oil with the introduction of GO sheets as additives.

No literature has covered the tribological behaviour of GO sheets in bio-oil. This study contributes to accelerating the application of bio-oil.

This paper aims to investigate the influence of stearate types on the thickening ability, dropping point and fiber structure of greases.

Several greases were prepared from polyolefins and various stearates. The melting point of the stearates and the dropping point of the resultant greases were measured, and the intermolecular binding energies of the thickener and the radial distribution function of the metal–oxygen in the thickener were determined with the aid of molecular simulation. The microstructures of the greases were also analyzed via scanning electron microscopy.

A higher stearate binding energy was found to correlate to a higher dropping point of the resultant greases. The thickening ability of the stearate is related to the group and period of the constituent metal ion. Within a group, greater atomic numbers of the metal were correlated to lower thickening ability. In a period, as the atomic number of the metal increased, the thickening ability was enhanced. The radial distribution functions of metal and oxygen can explain the aggregation of the stearate thickeners in the grease.

This work compared the thickening capacity of several stearates. Guidelines for preparing stearates to tailor the resultant grease are presented.

The purpose of this paper is to explore the synergistic lubrication of MoS₂ particles with different morphologies.

The synergistic lubrication of MoS₂ particles with different morphologies is evaluated using a four‐fall tribometer in liquid paraffin.

Results show that the morphology of MoS₂ has an influence on the tribological properties of MoS₂. Both MoS₂ nano‐balls and nano‐platelets function as lubrication additives in liquid paraffin better than MoS₂ micro‐platelets do. It is also found that there is a synergistic lubrication between two different morphologies of MoS₂. The composite MoS₂ additives with different morphologies can improve the wear resistance and friction reduction of liquid paraffin more than each of them singly does. The synergistic lubrication between two different MoS₂ morphologies results from the cooperation of their different lubrication mechanism.

The paper reveals a synergistic lubrication between two different MoS₂ structures. It is very advantageous and practical to partly displace nano‐MoS₂ with micro‐MoS₂.

The purpose of this paper is to develop a new oil‐in‐water (O/W) emulsion used for alpha phase brass, which can increase the antiwear and anti‐galling abilities of the rollers, and improve the surface quality of the rolled brass sheet. The aim is to evaluate the tribological performance of new kind of O/W emulsion for the hot rolling of alpha brass, which provides the fundamental information for the selecting of new chemical group, and to understand the lubrication mechanism of the used rolling emulsion and to correlate the laboratory findings with those of industrial rolling of alpha phase brass.

According to the hydrophile‐lipophile balance theory and the evaluation results of friction, wear and lubrication using a four‐ball tribometer, a novel O/W emulsion was developed for the hot rolling process of CuZn₃₂(ASTM C26200) and CuZn₃₀(ASTM C26000) alloys by controlling the composition of the emulsion, such as emulsifying, antiwear, extreme pressure, antirust and so on. By scanning electron microscope (SEM), energy‐dispersive X‐ray (EDX), and roughness profile the tribological mechanism were studied.

The production result proved that it was easy to control the accuracy and size of the brass sheet because of the emulsion‐jet to the roller surface directly and in succession. Polyol with hydroxyl group is found to provide better lubrication and lower coefficient of friction. The actual hot rolling results proved that it was easy to control the accuracy and size of the brass sheet with the emulsion jet. The morphologies and roughness profile of the copper sheet surface were observed and measured by SEM and topographic meter under different lubricant conditions. The in situ results supported the selection of compositions of O/W emulsion. The suitable temperature of feed emulsion is over 20°C.

The tribological mechanism of friction modified emulsion is not still clear. The thermal mechanical properties of rollers under this kind of emulsion are also worth studying in the future.

Understanding the tribological behaviour of O/W emulsion, will be useful for emulsion chemists, tribologists and rolling mill users.

The current study shows new compositions of O/W emulsion used for hot rolling of alpha phase brass.

When carrying out bioremediation of water polluted by biomass‐oil, the stains which can degrade the biomass‐oil efficiently should first be found. The purpose of this paper is to describe how adopted acclimation through the isolated strains degraded efficiently, and got reaction kinetics property.

During the acclimation, the biodegradation process of biomass‐oil is accorded approximately with the first‐order reaction by the way of Sturm method which is described by measuring CO₂ volume from the microbes' production.

One kind of microbe, Aspergillus versicolor, separated from the activated sludge in the aeration tanks of paper‐mill, is found to have the advantage of biodegradation in case of biomass‐oil from rice straw by rapid thermal‐liquidizing process. The biodegradation ability could be improved in aqueous culture under neutral and acidic conditions. The optimal temperature for biodegradation of biomass‐oil is 40°C. The optimal inocula content for biodegradation of biomass‐oil was 16 vol%.

The variation of lubricity of biomass‐oil with biodegradation needs more attention.

A basic research on the growth of a strain is shown, which is helpful for the biological treatment of biomass‐oil pollution.

One kind of fungi, Aspergillus versicolor, can be used for the biodegradation of biomass‐oil. The effects of various conditions or parameters on biodegradation of biomass‐oil are discovered in aqueous culture conditions in the case of Aspergillus versicolor.

To provide a suitable useful mixing ration of nano‐sized molybdenum disulfide and commercial common molybdenum sulfide (MoS₂) particles (approximately 1.5 μm in diameter) in liquid paraffin, which can lead to a better tribological performance.

The MoS₂ nanoparticles and commercial common MoS₂ particles (approximately 1.5 μm in diameter) were dispersed in liquid paraffin with different concentrations and ratios by means of ultrasonic in order to study their lubrication capacity, friction reduction and wear resistance. The tribological experiments were carried out by MQ‐800 four‐ball tribometer, in which extreme pressure, wear scan diameter and friction coefficient were measured. It was analyzed that the chemical status of elements on the rubbed surface by X‐ray photoelectron spectroscopy (XPS), and it was observed that the surface topography of wear scan by scanning electron microscope (SEM).

The results showed that the loading capacity of liquid paraffin with different kinds of MoS₂ particles were increased with their contents. The liquid paraffin containing the mixture of MoS₂ nanoparticles and common MoS₂ particles has a better wear resistance, friction‐reducing performance and extreme pressure property than the liquid paraffin containing pure common MoS₂ or pure nano‐MoS₂ particles. The optimal mixing ratio of nano‐MoS₂ and common MoS₂ is 20 wt percent, the loading capacity reaches the highest value. By XPS and SEM it was suggested that the difference in the tribological performance between MoS₂ nanoparticles and MoS₂ common particles was attributed to the surface and interfacial size‐effect of nanoparticles and the formation of molybdenum trioxide thin film on the rubbed surface.

It is not studied that the effects of mixing of common MoS₂ and nano‐MoS₂ in the actual lubricating oil with various additives.

It provided a basic research results and data for the application of nano‐MoS₂ particles.

The mixing of nanoparticles and non‐nano‐sized particles will lead to new tribological results, which is different from results obtained from other nanoparticles before.