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An onion-like carbon material was prepared from candle soot, and its tribological properties as an additive were investigated in water. The material assumed a spherical shape with a layered nanostructure based on high-resolution transmission electron microscopic analysis and had considerable sp hybrid carbon as revealed by Raman spectroscopy. The tribological properties were determined on an optimal SRV-IV oscillating reciprocating friction and wear tester. The results indicate that these candle soots as additives are able to effectively reduce both the friction and wear of sliding pairs in water. In addition, the chemical reactivity, physical stability, surface charge, and size of candle soot had a key impact on their lubrication properties. Based on our characterization of the wear scars by scanning electron microscopy and in situ Raman spectroscopy, we suggest a rolling and sliding lubrication mechanism. [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 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]

Purpose – In order to develop novel high EP S-containing additives and to meet the need of formulating GL-5 gear oil or other high EP lubricating oils, aims to investigate the tribological behaviors and mechanism of a di(iso-butyl)polysulfide (DIBPS), which was synthesized from some cheap materials at low temperature and under normal atmospheric pressure, as an additive in some mineral base oils compared with the traditional sulfurized olefin (SO) additive. Design/methodology/approach – The DIBPS additive was designed and synthesized, of which the main composition is the di(iso-butyl)trisulfide. Its load-carrying capacity, anti-wear and friction reduction properties as additive in some mineral base oils, compared with the traditional SO additive, were investigated using a four-ball machine and a Timken tester according to relative testing standards. The tribological mechanism was discussed according to the SEM and XPS analytical data. Findings – The results indicate that the four-ball PD value and the Timken OK value of the prepared DIBPS in VHVIS500 is clearly better than that of the traditional SO; the anti-wear property of DIBPS is equivalent to the traditional SO and the friction reduction effect of DIBPS is better than that of the traditional SO. The SEM and XPS data show that the DIBPS additive experiences different tribochemical reaction during tribological process compared with the traditional SO. The S active element of DIBPS reacted with surface metal mainly to form FeSO4 and/or Fe2(SO4)3 inorganic film, but the S active element of the traditional SO reacted with the surface metal mainly to form FeS inorganic film. This may be the chief reason why the prepared DIBPS possesses better EP properties than the SO. Research limitations/implications – The results show that the polysulfide additive (DIBPS) possesses better extreme pressure property than the traditional SO. However, more experimental study such as the synergic effect with other additives must be performed, from which it will be clearly shown whether the novel polysulfide can be applied in industrial oils. Practical implications – These results may be useful for the researchers to formulate some high EP industrial oils. Originality/value – This paper proves that the designed polysulfide additive, of which the main composition is the trisulfide, possesses better extreme pressure property than the traditional SO, and its tribological mechanicsm is also different with that of SO. It is noticed that the preparative method of this novel polysulfide additive has some superiorities, such as: low-experimental temperature, low-experimental pressure and cheap materials. [ABSTRACT FROM AUTHOR]

Purpose – In order to formulate ashless GL-5 gear oils and high-pressure antiwear hydraulic oils, the performances of extreme-pressure (EP) and antiwear (AW), and the thermal and hydrolytic stability of series ashless P-containing additives with different chemical structures are investigated by four-ball EP test, high-temperature oxidation test and hydrolytic stability test.Design/methodology/approach – Series ashless P-containing EP and AW additives with different chemical structures were designed and selected, their EP and AW performances, high-temperature oxidation, hydrolytic stability compared with the traditional zinc dialkyldithiophosphate (ZDDP) additive were investigated according to relative testing standards, and their applied performances compared with the traditional ZDDP additive were investigated using the CRC L-37 gear oil rear axle test, Deniso T-5D Vane Pump test and Deniso P-46 Piston Pump test.Findings – The results indicate that two ashless neutral thiophosphate esters exhibit excellent EP and AW performances, high-temperature oxidation and hydrolytic stability. The application performance of these P-containing additives is also examined by CRC L-37 rear axle test. The results show that only the oil samples with the addition of neutral thiophosphate esters correspondingly to API GL-5 automotive gear oil can pass the CRC L-37 gear oil rear axle test successfully. The results of further Deniso T-5D Vane Pump and Deniso P-46 Piston Pump tests prove that the ashless neutral thiophosphate ester is a very effective EP/AW additive for high-pressure antiwear hydraulic oil. In one sentence, the neutral thiophosphate ester is the excellent ashless EP/AW additive and the useful substitute for ZDDP.Research limitations/implications – From the results, the neutral thiophosphate ester is the excellent ashless EP/AW additive and the useful substitute for ZDDP, however, their tribological mechanicsm and their synergic effect with the other additives used in the test base oil for the applied performance tests may be done in the future works.Practical implications – These results may be useful for the researchers to formulate some ashless high EP/AW industrial oils.Originality/value – This paper proves that the two ashless neutral thiophosphate esters exhibit excellent EP and AW performances, high-temperature oxidation and hydrolytic stability, and is the useful substitute for ZDDP for formulating ashless GL-5 gear oils and high-pressure AW hydraulic oils. [ABSTRACT FROM AUTHOR]

The effect of hexakis(1,1,5-trihydroperfluoropentoxy)cyclotriphosphazene (X-100) and a novel synthetic bridged alkoxycyclotriphosphazene (denoted LA-2P) as additives in Z-DOL, a perfluoropolyether-type lubricant, on the friction and wear behavior of a steel-on-steel system was investigated. Thus, the friction and wear test of a steel disc sliding against the same steel counterpart ball was carried out on an SRV oscillating friction and wear tester. The chemical features of the worn steel surfaces were analyzed by means of X-ray photoelectron spectroscopy. The results indicate that both additives are effective in improving the tribological performance of Z-DOL and in preventing its catalytic decomposition. Z-DOL/LA-2P shows the best anti-wear ability. Moreover, both additives also increase the thermal stability of Z-DOL in the presence of AlCl3 as a catalyst. In particular, the Z-DOL/LA-2P mixture shows the highest complete thermal degradation temperature. [Copyright &y& Elsevier]

Abstract An in situ preparation of multifunctional additives in water was firstly developed in this paper. The additives can be conveniently obtained by stirring anionic raw materials benzotriazole (BTAH) and cationic materials tetrabutyl ammonium hydroxide (N 4444 OH) or tetrabutyl phosphonium hydroxide (P 4444 OH) in water. The physicochemical and tribological properties of the obtained additives benzotriazole tetrabutylammonium (N 4444 BTA) and benzotriazole tetrabutylphosphonium (P 4444 BTA) were systematically studied. Compared with traditional water-based lubricant additives, they are simple to prepare, have excellent tribological properties and good solubilities in water. In addition to their excellent tribological properties, these additives also show significant corrosion resistant abilities, which make them multifunctional additives for water based lubricants. Graphical abstract Water-based lubricating additives P 4444 BTA and N 4444 BTA were prepared in situ in aqueous solution. The additives were found not only easy to be prepared, but also have excellent tribological properties. In addition to their significant tribological properties, these additives also show excellent corrosion resistant ability, which makes them multifunctional additives for water based lubricants.Evolution of the friction coefficients (a) and wear volume losses(b) for different samples on copper/steel friction pairs. Image 1 Highlights • An in situ preparation of multifunctional additives in water was presented. • The preparation is extremely simple to realize with high efficiency. • The obtained additives were found to have excellent tribological properties. • The additives also show excellent corrosion resistant ability. [ABSTRACT FROM AUTHOR]

Two novel PN type ionic liquids (ILs) surfactants, N-(3-(diethoxyphosphoryl) propyl)-N,N-dimethyloctadecan-1-aminium-6-methyl-4-oxo-4H-1,2,3-oxathiazin-3-ide-2,2-dioxide and N-(3-(diethoxyphosphoryl)propyl) -N,N-dimethyl octadecan-1-aminium-2,3,4,5,6-pentahydroxyhexanoate were synthesized and investigated as a potential water-based lubricant additive. Unlike other ILs with low solubility, these ILs surfactants are stable and miscible with water-diethylene glycol. Remarkably, these additives reduce the corrosion of water on the steel and improve friction and antiwear function for the steel surface with lower friction coefficient and wear volume. Based on the results of mechanism analysis, we speculate a boundary lubricating protection film containing phosphorus and nitrogen formed on the sliding steel surfaces, achieving excellent tribological properties by a phosphorus-nitrogen synergy. [ABSTRACT FROM AUTHOR]

Perfluoropolyether (PFPE) lubricant is widely used in plenty of cutting-edge technologies because of its extraordinary properties. However, poor boundary lubrication and creep limit their further applications. Here, we demonstrated a PFPE supramolecular gel with surface-functionalized Ti 3 C 2 T x as additives for highly efficient boundary lubrication and prevention of creep. It turned into an oily liquid at 124.5 °C, accompanied by a rapid decrease in viscosity. Additionally, the phase transition could be achieved by shear stress. This kind of gel reduced wear volume by 90.75% compared with pure PFPE oil. Its friction coefficient (∼0.113) varied slightly with time. Notably, its load-bearing capacity exceeded 1500 N. This work puts forward an approach to the preparation of PFPE-based supramolecular gel lubricant with surface-functionalized Ti 3 C 2 T x additive. [Display omitted] • BPBD gelator was synthesized through the one-pot method to gelatinize PFPE. • The framework formed by non-covalent interactions between the gelator could trap oil. • PFPE gel with PPFMA-g-Ti 3 C 2 T x prevented oil creep and additive sedimentation. • PFPE gel with PPFMA-g-Ti 3 C 2 T x had thermal reversibility and thixotropy. • PFPE gel with PPFMA-g-Ti 3 C 2 T x could withstand a normal load exceeding 1500 N. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) were modified by imidazolium-based ionic liquid (IL), 1-hydroxyethyl-3-hexyl imidazolium tetrafluoroborate and used as an additive in base stock IL 1-methyl-3-butylimidazolium tetrafluoroborate as the base lubricant. The effectiveness of using the IL- modified MWCNTs as lubricant additive was evaluated using a ball-on-plate configuration on an Optimol SRV oscillating friction and wear tester. The worn surfaces were examined using scanning electron microscope and the chemical composition on wear tracks was analyzed on an X-ray photoelectron spectrometer. Results suggest excellent anti-wear properties for the IL-modified MWCNTs as lubricant additive. [ABSTRACT FROM AUTHOR]

Abstract: The anti-wear and antioxidant behaviors of 2,2,6,6-tetramethyl-1-piperidinooxy (TEMPO) and its derivatives were studied. The tribological properties of lubrication oils with or without the addition of TEMPOs were investigated on an Optimol SRV IV oscillating friction wear tester and the oxidative stability was evaluated by RBOT test using SH/T-0193 and ASTM D2272 procedures. The results showed that the addition of TEMPOs can improve the antiwear and antioxidant behaviors of lubrication oils remarkably. Moreover, the addition of TEMPOs can improve the performance of lubrication oil under atomic oxygen radiation. [Copyright &y& Elsevier]

Abstract: Two ashless and non-phosphorus hydroxyl-containing dithiocarbamate-triazine compounds, 2,4,6-tri[N,N-di-n-butyldithiocarmate-(2′-hydroxyl)-propionylthio]-1,3,5-s-triazine (LDBA) and 2,4,6-tri[N,N-di-i-octyldithiocarmate-(2′-hydroxyl)-propionylthio]-1,3,5-s-triazine (LDIOA), were prepared and their tribological behaviors as additives in rapeseed oil (RSO) were evaluated using a four-ball tester. Thermal degradation tests were conducted to identify their thermal stabilities using a thermo-gravimetric analyzer. The worn surfaces of the steel balls were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). The results indicate that the additives possess high thermal stabilities and good load-carrying capacities. Moreover, they both have good anti-wear and friction-reducing property at relatively high concentration (>1.5wt%) and under all test loads. The results of XPS analyses illustrate that the prepared compounds as additives in RSO forms a protective film containing inorganic sulfide, sulfate, oxidized compounds and organic nitrogen-containing compounds on the metal surface during the sliding process. [Copyright &y& Elsevier]

Three S-(1H-benzotriazole-1-yl) methyl N,N-dialkyldithiocarbamates were synthesized and their tribological behaviors as additives in rapeseed oil (RSO) were evaluated using a four-ball tester. Thermal degradation tests were conducted to identify their thermal stabilities using thermogravimetric analyzer (TGA). The worn surface of the steel ball was investigated by X-ray photoelectron spectroscopy (XPS). The results indicate that the additives possess excellent load-carrying abilities and high thermal stabilities, but have no antiwear and friction-reducing properties. Based on the results of XPS analysis, it can be seen that tribochemical reactions occur between the synthesized compounds and metal surfaces during the sliding process. [Copyright &y& Elsevier]