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The purpose of this study is to reduce the use of Zinc dialkyl dithiophosphates (ZDDP) and improve the frictional properties and thermal oxidation stability of Perfluoropolyether (PFPE) grease by adding antioxidant additives. The addition of antioxidants can reduce the consumption of ZDDP as an antioxidant, thus improving the anti-wear efficiency of ZDDP and reducing the excess phosphorus element in the grease.

In this study, an antioxidant with good comprehensive performance was selected from several antioxidants by tribological tests and high-temperature tests. Then, the effect of its combination additive with ZDDP on PFPE grease was investigated. The anti-wear property, anti-friction property, thermal oxidation stability and extreme pressure property of greases containing different proportions of ZDDP and antioxidant were tested by four-ball tester and synchronous thermal analyzer (STA). The effects of additives on properties of grease were analyzed by SEM, EDS, LSCM, XPS and FT-IR.

The research shows that 2,6-Di-tert-butyl-4-methylphenol (BHT) can be used as an antioxidant in combined additives to reduce the antioxidant reactions of ZDDP, thus improving the anti-wear efficiency of ZDDP and further enhancing the anti-wear performance of the grease. Moreover, BHT and ZDDP have a synergistic effect on the high temperature performance of the PFPE grease due to their different antioxidant mechanisms.

In this paper, the problems related to PFPE grease are studied, which has a certain guiding effect on the industrial application of fluorine grease and the related formulation design.

In this paper, the properties of PFPE grease under different lubricating condition were studied. The synergistic lubrication effect of antioxidant and ZDDP are discussed. It provides experimental and theoretical support for reducing the content of ZDDP and improving the performance of additives.

This paper aims to introduce a high-temperature grease design method assisted by back propagation neural network (BPNN) and verify its application value.

First, the grease data sets were built by sorting out the base data of greases in a large number of literatures and textbooks. Second, the BPNN model was built, trained and tested. Then, the optimized BPNN model was used to search the unknown data space and find the composition of greases with excellent high-temperature performance. Finally, a grease was prepared according to the selected composition predicted by the model and the high-temperature physicochemical performance, high-temperature stability and tribological properties under different friction conditions were investigated.

Through high temperature tribology experiments, thermal gravimetric analysis and differential scanning calorimetry experiments, it is proved that the high temperature grease prepared based on BPNN has good high-temperature performance.

To the best of the authors’ knowledge, a new method of designing and exploring high-temperature greases is successfully proposed, which is useful and important for the industrial applications.

The purpose of this paper is to examine the tribological behavior of the synthetic chlorine‐ and fluorine‐containing silicon oil as an aerospace lubricant.

The chlorinated‐phenyl and methyl terminated silicone oil (CPSO), chlorinated‐phenyl and trifluorinated‐propyl with methyl terminated silicone oil (FCPSO) were prepared. Their physical properties such as saturated vapor pressure and the evaporation weight loss were evaluated. The tribological properties of the silicon oils under moderate load were investigated with an Optimol SRV oscillating friction and wear tester, as well as Four‐ball friction and wear tester according to the standard method of ASTM D 4172 under higher load. The elemental composition generated on steel ball surface were analyzed on a scanning electron microscope with a Kevex energy dispersive X‐ray analyzer attachment (SEM/EDS), and the chemical nature of elements on worn surface lubricated with FCPSO were studied by X‐ray photoelectron spectrometer (XPS).

It is found that the CPSO and FCPSO show good tribological behavior for steel/CuSn alloy tribological pairs and are superior to hosphazene (X‐1P) and perfluoropolyether in terms of friction‐reduction ability and anti‐wear performance. The anti‐wear performance of FCPSO as lubricants for steel‐steel contacts is superior to CPSO. The EDS results showed existence of F and Si on the worn surface with lubrication of FCPSO, while XPS results indicated the occurrence of tribochemical reaction of FCPSO with friction pair during sliding process with the formation of FeCl₂, FeF₂ and the absorption silicon oil films on the lubricated metal surface.

The results substantiate that chemical reactive elemental such as chlorine or fluorine, which is substituted into silicon oil, helps to improve the anti‐wear and load‐carrying capacity of the liquid lubricant. So the excellent thermal stability, low‐temperature fluidity, very low‐saturated vapor pressure and excellent lubricity for steel/CuSn alloy of the silicon oil of FCPSO and CPSO make it an attractive alternative to conventional liquid lubricant for space mechanism.

Recently, much effort has been focused on research and development of new types of lubricating oil additives to reduce wear and friction in the tribological systems. It has been noted that the use of additives to improve the lubricating capacity and durability of oil plays an important role in the wear and friction process of materials. Due to the environmental problems, many researchers are embarking on the viability of the vegetable‐based lubricants. In this article a critical review has been made on vegetable‐based lubricant additives with specific properties and application. This article explains the advantages and manufacturing processes of vegetable‐based oils, which will give a better understanding of using biodegradable lubricating oil additives. A case study on palm oil methyl ester as an additive has been presented in this paper.

This paper aims to propose a new strategy to functionalize zeolitic imidazolate frameworks (ZIF-8) to improve its dispersion stability and tribological properties in lubricating oil.

Dialkyl dithiophosphate polydopamine ZIF-8 (DDP@PDA@ZIF-8) was prepared via mussel-inspired chemistry and the Michael addition reaction. The tribological properties of DDP@PDA@ZIF-8 as an additive in the white oil were evaluated with four-ball friction and wear tester at different temperatures. The worn surface was analyzed using X-ray photoelectron spectrum (XPS).

The as-prepared DDP@PDA@ZIF-8 shows high dispersion stability in the white oil. Tribological results confirmed that the DDP@PDA@ZIF-8 exhibited a small wear scar diameter at 25°C. However, excellent friction reduction and anti-wear properties were observed at 75°C. The XPS result indicates that a series of tribochemical reactions occurred on the worn surface, forming the complex protective film.

This paper provides a study of highly dispersed ZIF-8 as lubrication additives.

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/

The purpose of this paper is to investigate the tribological properties of Si₃N₄ sliding against Dy−sialon ceramics lubricated by two novel phosphazenes bridged fluorophenoxycyclotriphosphazene (coded as L‐2P) and metal halide‐stabilized linear phosphazene derivatives (coded as LMZn‐3). The traditional phosphazene tetrakis (3‐trifluoromethylphenoxy)‐bis(4‐fluorophenoxy) – cyclotriphosphazene (X‐1P) was also tested as the reference.

The lubricity characteristics of phosphazene derivatives were evaluated on an Optimol SRV oscillating friction and wear tester. The morphology of the worn sialon surface was analyzed with a scanning electron microscope (SEM) and X‐ray photoelectron spectroscope (XPS).

The two novel phosphazenes are effective lubricants for Dy−sialon and show superior tribological properties to traditional phosphazene X‐1P and glycerol. Among all lubricants, linear phosphazene LMZn‐3 exhibits the lowest wear volume loss at 20°C or 100°C. Moreover, LMZn‐3 and L‐2P show much better antiwear ability than X‐1P under higher load than 60N. The decreased friction coefficient and wear volume of Dy−sialon ceramics under lubrication of the phosphazene lubricants are attributed to the tribochemical products mainly consisting of organic oxyfluoride or carbonfluoride species and silicon fluoride.

The paper deals with only limited compounds. The paper works on the subject progressively to explore more combinations for better tribological properties.

The phosphazene derivatives present better tribological performance used as base oils and additives.

There are few data about other phosphazene with different structures, such as bridged cyclotriphosphazene and metal halide‐stabilized linear phosphazene, used as lubricants for ceramics materials.