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Purpose – 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. Design/methodology/approach – 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). Findings – 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. Research limitations/implications – The paper deals with only limited compounds. The paper works on the subject progressively to explore more combinations for better tribological properties. Practical implications – The phosphazene derivatives present better tribological performance used as base oils and additives. Originality/value – 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. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the influences of test conditions to the tribological behavior of LaF3 nanoparticles as an additive to a polyalphaolefin (PAO). Design/methodology/approach – An Optimol-SRV4 oscillating friction and wear tester (SRV) were used to investigate the tribological properties of LaF3 nanoparticles as an additive in a polyalphaolefin (PAO). The 3-D morphologies and wear loss volume of the worn scar were measured using a surface profilometer. The chemical state and the intensity of La and F elements on worn surface after friction test was investigated with X-ray photoelectron spectroscopy to interpret the possible mechanisms of friction-reduction and anti-wear with LaF3 nanoparticles. Findings – The experimental results show that LaF3 nanoparticles added to PAO exhibit excellent load-carrying capacity, anti-wear and friction-reduction properties. LaF3 nanoparticles deposited on the worn surface under lower test temperature during the friction test, and higher applied load, higher test frequency and longer test duration are propitious to the deposition of LaF3 nanoparticles accumulated on the rubbing surface. Under higher temperature, a complicated tribo-chemical reaction occurred during the friction process, the tribo-chemical reaction product of La2O3 deposit on worn surface, which also exhibits good lubricating performance. Originality/value – This paper investigates the tribological properties of LaF3 nanoparticles as green oil additive in poly-alpha-olefin (PAO) under variable temperature, applied load, sliding speed and sliding duration. The results could be very helpful for the further applications of LaF3 nanoparticles additives in industry. [ABSTRACT FROM AUTHOR]

Purpose - The aim of this paper was to inhibit the serious corrosion of conventional ionic liquids, a series of new ionic liquids (ILs) containing the triazole functionality, as the anti-corrosion groups were synthesized in this work. Design/methodology/approach - It is well known that nitrogen and sulfur containing organic compounds have been traditionally used as corrosion inhibitors. Among them, triazole derivatives are most often used as corrosion inhibitors. To alleviate the corrosion of the ILs and further improve the anti-wear property, the authors prepared a series of imidazolium ILs modified with the triazole functionality in the present study. Findings - The corrosion behavior of the ILs was evaluated with the iron disk corrosion test and their tribological properties were investigated on an Optimol SRV IV oscillating friction and wear tester at elevated temperatures. The results showed that the ILs with the triazole functionality could effectively reduce the corrosion and exhibit a smaller friction coefficient and wear volume than the unmodified counterpart. The ILs containing the triazole functionality can be used as the single component anti-corrosion base oils even at elevated temperatures. Originality/value - The results showed that the ILs with the triazole functionality could effectively reduce the corrosion and exhibit a smaller friction coefficient and wear volume than the unmodified counterpart. The ILs containing the triazole functionality can be used as the single component anti-corrosion base oils even at elevated temperatures. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study a novel Mannich adduct of benztriazole-containing diphenylamine (coded as BD) and its anti-oxidation properties as an additive in two typical synthetic ester-based oils. Design/methodology/approach – The anti-oxidation properties in two typical synthetic ester-based oils were evaluated in detail, using rotating pressure vessel oxidation test. The tribological properties of BD in synthetic ester-based oil (A51) were also tested with Optimal SRV-I oscillating friction and wear tester at atmosphere. Findings – The results of tests demonstrated that the novel BD compound is, indeed, a high-performance anti-oxidation additive that was able to remarkably improve the oxidation stability of synthetic ester-based oils, when it was added at only 0.5 per cent concentration and compared with the base oils containing 0.5 per cent of the commercial available antioxidant additives such as 2, 6-di-tert-butyl-4-methylphenol and octyl-butyl diphenylamine. A plausible mechanism of exceptional synergistic anti-oxidation was proposed. Originality/value – This paper first investigated the anti-oxidation properties and mechanisms of the compound with the structure of BD, which can be very useful and would promote the application of BD antioxidant in the lubricant industry. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the antirust, tribological performance and anti-wear (AW) mechanism of the of soybean lecithin (SL) as a kind of multifunctional lubricant additive. Design/methodology/approach – As a kind of multifunctional lubricant additive, the antirust performance of SL was tested according to ASTM D 665, and meanwhile, its tribological performances were also evaluated by Optimol SRV-I oscillating reciprocating friction and wear tester and four ball tester. The worn steel surfaces were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Findings – The results showed that the SL exhibited excellent antirust properties in different base stock, and could effectively improve the AW and extreme pressure (EP) performances. The results of SEM and XPS indicated that a protective film was formed between steel-steel friction pair during the tribological test. Originality/value – This paper first investigated the antirust properties and the tribological mechanism of the SL as a kind of multifunctional lubricant additive, which can be very useful and will promote the application of SL in lubricant industry. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the tribological performance of tri(hydroxymethyl)propane esters containing boron and nitrogen as lubricant additives in rapeseed oil. Design/methodology/approach – Thermal degradation tests were performed to analyze their thermal stability using a thermo-gravimetric analyzer. Two four-ball testers were used to measure the tribological properties of tri(hydroxymethyl)propane esters containing boron and nitrogen as lubricant additives in rapeseed oil. The worn surfaces of steel balls were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Findings – The results show that the tri(hydroxymethyl)propane esters containing boron and nitrogen have excellent thermal stability, good antiwear performance, improve the load-carrying capacity, and possess friction-reducing behavior especially at 98 N when they are used as additives in rapeseed oil. The results of XPS show that the adsorption and tribochemical reactions have been occurred to form a complex boundary lubrication film. Originality/value – The paper illustrates two novel tri(hydroxymethyl)propane esters which contain B and N elements used as additives in rapeseed oil. The results are useful for further applications in advanced environment friendly lubricating oils and additives. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to prepare water-soluble TiO2 nanoparticles and evaluate the tribological properties as additives in water. Design/methodology/approach – Nanoparticles present excellent friction-reducing and antiwear properties as additives in base oils. However, there are seldom literatures about the nanoparticles as additives in water as yet. In this work, water-soluble TiO2 nanoparticles were prepared by sol-gel method and characterized with transmission electron microscopy and selected area electron diffraction. The tribological properties as additives in water were investigated by SRV and the surface analysis by scanning electron microscope and X-ray photon electron spectroscope. Findings – TiO2 nanoparticles modified with polyethylene glycol have uniform size about 10 nm and easily dissolve in water. The tribological experiments showed TiO2 nanoparticles exhibit excellent friction-reducing and antiwear properties. Research limitations/implications – The paper is restricted to only TiO2 nanoparticles. Some other water-soluble nanoparticles also should be prepared and their tribological properties investigated. Practical implications – Water-soluble TiO2 nanoparticles could be used as water additives and improve the tribological properties. Originality/value – This paper emphasises that the water-soluble nanoparticles are prepared and could be used as water additives. [ABSTRACT FROM AUTHOR]