МОДЕРНИЗИРОВАННАЯ МАШИНА ТРЕНИЯ

The most widely used standard tests for the evaluation of wear and extreme pressure properties are analysed in terms of eight tribological parameters. Wide variations in the test conditions are disclosed and the over-riding influence of thermal conditions on test severity is made clear. The relation between tests, such as the Timken, in which one of the two rubbing surfaces is static, and gear or cam and follower tests in which both specimens move, is explored. A preliminary account is given of a new test procedure evolved as a result of the study.

Chemical reactivity, extreme-pressure (EP), and antiwear (AW) properties of binary additive systems were investigated using the hot-wire method and using four-ball test machines. Auger electron spectroscopy was also used to examine the thin wire surface and the wear scar surface for further understanding of the interactions between the EP and AW additives with iron surfaces. The results indicate that the antiwear properties of the EP and AW additives are strongly influenced by petroleum calcium sulphonate and hexadecamine salt of benzotriazole. However the extreme-pressure property is not affected by these additives. The presence of petroleum calcium sulphonate reduces the antiwear properties of these three EP and AW additives, due to its retardation of reactions of the EP and AW additives on iron surfaces. The presence of hexadecamine salt of benzotriazole improves antiwear property of the three EP and AW additives tested, most likely because it enhances their chemical reactivity. Presented at the 46th A...

The tribological performance and tribochemical analysis of novel borate esters as lubricant additives in rapeseed oil

The synergistic effects of EP and AW additives with oxynitrided surface of steel

Friction and wear characteristics of p-containing antiwear and extreme pressure additives in the sliding of steel against aluminum alloy

Study to examine future of wear-resistant materials

DLC coating of boundary lubricated components—advantages of coating one of the contact surfaces rather than both or none

PurposeIn 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.

Solid lubricants (SLs) are known to enhance the tribo-performance of oils significantly. Polytetrafluoroethylene (PTFE) particles have proved as an excellent extreme-pressure additive (EPA) but not as so good anti-wear additive (AWA). In contrast, the graphite nano-particles (NPs) are known as very good AWA but not so promising EPA. In this context, graphite and PTFE particles with different shapes (graphite-laminar and PTFE- spherical) and sizes (graphite- 60–120 nm and PTFE- 11–13 μm) were used in combination in different amounts for exploring possible synergism as AWA and EPA. A series of oils based on Group III (Gr III) with polyisobutylene succinimide (PIBSI) dispersant (1 wt%) along with an increasing amount of graphite NPs (0%–4%) and a simultaneous decrease in PTFE NPs (4%–0%) was prepared. The tribo-performance of oils was evaluated on Four ball tester for EP (weld-load) and anti-wear performance. Formulations were characterized for density, viscosity, and viscosity index. Also, the stability of oils was monitored through visual observation, and it was more than two months. Combo-oils showed improvement in anti-wear (AW) performance up to 54% for the concentration of 2 wt% each. For AW, synergism was observed, while for extreme pressure (EP) property, PTFE particles in isolation proved best, showing almost 350% improvement for group III oil. The inclusion of graphite particles step by step deteriorated the performance. The SEM (Scanning electron microscopy) and EDAX (Energy-dispersive X-ray) were used to analyze worn surfaces of ball and film formation mechanism.

Higher demands on extreme pressure lubrication performance are posed by stringent working conditions. In this study, the synergistic tribological properties of phosphate ammonium salt in combination with active sulfurized olefin (S1) and non-active sulfurized fatty acids (S2) were investigated to meet the needs under stringent working conditions. The anti-wear mechanisms were further explored using scanning electron microscopy (SEM) with EDS, X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure (XANES), and focused ion beam microscopy. The experimental results indicate that P-S2 demonstrates superior friction reduction and wear resistance under low loads, potentially attributable to its higher polarity, whereas P-S1 exhibits better wear resistance under high loads. P-S1 also shows superior extreme pressure performance attributed to its higher active sulfur content and stronger film-forming ability, evidenced by a thicker friction film (82.62 nm vs. 24.28 nm for P-S2). The study highlights that the variations in the synergistic tribological performance of phosphorus- and sulfur-based additives may link to differences in molecular structure, active sulfur content, polarity, and corrosiveness, with P-S1 demonstrating enhanced extreme pressure performance possibly through the formation of a multi-layered friction film of polyphosphate, sulfide, oligophosphate, and sulfate layers.

The reactions of 1-chloropropanediol and 1-chloro-3-alkylcarboxymethyl-propanol-2 with alkylxanthogenates have been studied; mixtures of acyclic, cyclic xanthates and tritiocarbonates are formed. The dependence of the direction of the reaction and, accordingly, the yields of the synthesized compounds on the ratio of reagents and conditions of the experiments was revealed. The evidence that both acyclic and cyclic compounds are formed in these reactions are spectral (IR) and physicochemical (n_D^20, d_4^20, MRD, elemental composition). The obtained compounds were investigated as extreme pressure additives to lubricating oils, their effectiveness as extreme pressure additives was revealed. The high extreme pressure properties of the synthesized compounds are explained by the fact that their molecules contain polar thiocarbonyl (C=S), 1 sulfide (CS) sulfur in xanthates and 2 sulfide sulfur in tritiocarbonates, which are easily adsorbed on the metal surface, forming at high temperatures, protective layer consisting of metal sulfides. Due to the fact that all the obtained compounds are high-sulfur, they do not have antiwear properties, that is, they cause corrosive wear, in order to improve the corrosive properties of oils, the authors have compiled compositions using the antiwear and antioxidant additives DF-11.

PurposeIn 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/approachThe 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.FindingsThe 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/implicationsThe 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 implicationsThese results may be useful for the researchers to formulate some high EP industrial oils.Originality/valueThis 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.

The antiwear and extreme pressure properties of some oil-water double soluble rare earth complexes part 1: their tribological behaviour in water

The influence of a cross-linking agent, diamine, and C60 fullerene on the antifriction and wear properties of a solid lubricant made of trifluorochloroethylene-vinylidene fluoride copolymer was studied for steel-to-steel sliding friction. The wear characteristics are improved in the whole range of loads investigated, while the antifriction properties, only at small loads. A qualitative wear test method is proposed in which the test-period-averaged friction coefficient of a hybrid specimen (coating plus metal substrate) is measured with a standard friction machine. A model that considers the combined interaction of the substrate and the coating with the roller was used to calculate the linear wear rate of steel and the probabilistic parameter of wear.

Aluminum lead bronze bearing metal. (in Russian) : E. F. Merkulov. Tsvetnye metally, v. 30, June 1957. p. 67–69