Lubricant Composition Research Articles

Tribochemistry effect on the friction reduction of Al2O3/ethylene glycol composite lubricant between steel self‐mated tribosystem

In our previous work, we find that the ethylene glycol (EG) is transferred to amorphous carbon or graphene during sliding under the effect of the tribochemical reactions; herein, in this work, we control the concentration of the modified Al2O3 nanoparticles in the EG solution in order to modulate the tribological properties of the tribosystem sliding in the mixed lubricant consisting of the modified Al2O3 nanoparticles and EG. The tribological tests show that the concentrations of the modified Al2O3 nanoparticles ranging from 0 to 1.0 wt% in the mixed lubricant are helpful for obtaining low wear rate due to the formation of graphene‐like materials induced by tribochemical reactions. On the other hand, when the concentration reaches 1.5 wt.%, the tribosystem exhibits high coefficient of friction (COF) and wear rate, which is attributed to the formation of reunited groups consisting of the modified Al2O3 nanoparticles and graphene‐like materials. This investigation should give a positive guidance for the design of the mixed lubricant with excellent lubrication properties.

ИССЛЕДОВАНИЕ ИЗМЕНЕНИЯ ВЯЗКОСТИ СМАЗОЧНО-ОХЛАЖДАЮЩЕЙ ЖИДКОСТИ В ЗАВИСИМОСТИ ОТ РАЗМЕРА МАСЛЯНЫХ КАПЕЛЬ, КОНЦЕНТРАЦИИ ДИСПЕРСНОЙ ФАЗЫ И ВВЕДЕНИЯ ТВЕРДОФАЗНЫХ ВЫСОКОДИСПЕРСНЫХ МОДИФИКАТОРОВ

One of the ways to increase processing productivity and ensure high quality of the treated surface is the correct choice and use of lubricants and coolants. The solution to the problems of increasing efficiency was implemented by choosing the compositions of lubricants and coolants, which were prepared based on fat-and-oil waste products. This will ensure a reduction in the environmental burden on the environmental system. Also, the greatest attention has recently been paid to evaluating the effect of lubricants modified with carbon materials, in particular, carbon nanotubes and graphite. Due to the particular features of their physical and mechanical properties, carbon modifiers have an impact on cutting processes and rules of the impact have not been sufficiently studied so far. This article continues the study of changes in the viscosity of a water-oil emulsion coolant from varying the oil droplets size, the dispersed phase concentration and the introduction of solid-phase highly dispersed modifiers. It was found that reducing the size of oil droplets, increasing the concentration of the dispersed phase and modifying the water-oil emulsion coolant with highly dispersed carbon materials lead to an increase in viscosity.

Study on Effect of Hot Rolling Process Lubricant on Rolling Force and Thickness of Q235A Strip Steel

Taking the Q235A plate and strip as the research object, hot rolling experiments were carried out under different concentrations and compositions of hot rolling process lubricants, and the effect of different lubrication conditions on the rolling effect of the Q235A plate was studied. The experimental results show that the processing lubricant used for 3 # and 4 # samples has the best effect, and the thickness of the steel plate rolled with 10% lubricant is thinner than that with 5% lubricant. When the concentration of lubricant is 10%, the maximum reduction of the third pass rolling force is 24.4%. The rolling force with oil lubrication is 21% lower than that without oil lubrication.

Influence of Base Oil Molecular Structure on the Tribological Performance of Diesel Engine Cylinder Liner and Piston Ring

Highly intensified diesel engines lead to severe lubricating condition, high performance lubricant is important to solve this problem. Base oil is the main composition of lubricant, which plays important role in lubricating performance. In this paper, three kinds of poly-α-olefin (PAO) base oil were prepared. Different olefin materials were used to produce PAO with different molecular structure. The tribological performance of diesel engine cylinder liner and piston ring lubricated with different base oil were evaluated by reciprocating test rig. Results show that PAO base oil synthesized with long carbon chain olefin has high viscosity index. The PC12 reduced the friction coefficient by 15.4%/19.6% in low speed/high speed friction compared with PC8. The wear of PC12 reduced 15.8% compared with PC8. The results were resulted from the long carbon chain of PC12, which produce high viscosity in high temperature and shear thin effect in high speed friction.

Thermodynamic Analysis of a Composite Obtained Using a Mixture of Copper and Molybdenum Oxides and Sulphides

The purpose of the study is selecting the optimal composition of antifriction composites alloyed with refractory metal sulfides in copper-based systems and developing the design of a laboratory plant for the production of sinter by pyrolysis of coke chemistry production resins. The object of the study is antifriction composites based on rare metal sulfides and coke chemistry production resins. The methodology of the work is determined by the use of modern physical and chemical research methods and modern software systems. As a result of the studies, the probable chemical reactions between compounds of copper and rare metals: molybdenum, tungsten with and without the participation of carbon, have been compiled. The optimal compositions of antifriction composites based on copper and rare metal sulfides have been determined, and a laboratory plant has been designed for the production of sinter by pyrolysis of coke chemistry production resin. The scope of the results is materials science and technology of new materials. Based on the thermodynamic analysis of various reactions that are likely to occur during the preparation of the cladding carbon lubricant composition based on powdered copper and carbon with the addition of rare metal sulfides (MoS2), the most appropriate component composition of the charge has been selected. In this case, a reducing agent is used: soot obtained from resins of coke production that has an amorphous structure and does not have solid impurities. The main choice was made on the formation of metallic copper and disulfides of rare metals in the presence of active carbon. The most probable reaction is the formation of metallic copper and molybdenum disulfide in the presence of carbon. Carbon and copper are macro-components of the lubricant, and rare metal sulfides are additives that improve its plasticity. It is also important that carbon does not contain abrasive impurities and has certain hardness and fineness. These qualities are ensured in the production of black carbon using coke chemistry resins. To obtain black carbon, a laboratory plant has been designed that will be used for the pyrolysis of resin from the coke chemistry production.

Composition for Anticorrosive Treatment of Parts of Threaded Connections

Introduction. A review of studies on the protection of threaded connections from corrosion shows that they have leaks that contribute to the development of crevice corrosion, which leads to a decrease in the mechanical strength of threaded connections and complicates dismantling. Modern lubricants and chemical thread fixatives do not provide corrosion protection and disassembly of threaded connections over a long service life, so the development of a more effective lubricant composition is an urgent task. Aim of the Article. Is to develop an effective lubricant composition to protect against corrosion and improve the disassembly of threaded connections. Materials and Methods. The parts of the M10 threaded pair with a thread pitch of 1.5 mm made of St3 steel, connecting two products, (prototypes) were lubricated with grease Zh-SKa 2/6-2, lithol-24, grease + oligomer D-10TM 5% by weight, composition of litol-24 + oligomer D-10TM 5% by weight, tightened to the moment of tightening force 80 N‧m, immersed in a 3% hydrochloric acid solution at a temperature of 22‒24°С. After 8 hours, the samples were removed from the solution and left in the air for 16 hours, which represented one cycle. According to the lubrication options, the number of parallel experiments was 5. Exposure duration – 24; 48; 96; 240; 480; 720 hours, after the expiration of which 5 samples of each lubricant option were disassembled, the value of the moment of the release force was recorded, the corrosion damage was assessed, and the coefficient of friction was calculated. Results An effective lubricant composition has been developed for processing parts of threaded connections, which increases their corrosion resistance and improves dismantling. Discussion and Conclusion. When adding oligomer D-10TM 5% by weight in litol-24, there is a significant increase in the length of time before the appearance of foci of corrosion on the details of threaded connections and an improvement in their dismantling. Implementation of the obtained results allows to increase the reliability of threaded connections.

Strengthening of friction surfaces by using geomodifiers based on serpentines from the Dashukivka deposit

The object of research is the process of improving the tribological characteristics of friction joints, in particular anti-wear and anti-burr properties. There is a practice of using serpentines, so-called "friction geomodifiers" (FGM), as special repair and restoration additives. Their use leads to a decrease in the coefficient of friction and temperatures in the contact zone; an increase in the mass of parts is observed, which indicates the restoration of worn surfaces. The mechanism of formation of new structures is still unclear. There are hypotheses that severe friction conditions initiate micrometallurgical processes at the atomic-crystalline level, as a result of which modified layers with unique tribological characteristics are formed on the surfaces. A comparative analysis of the main indicators of serpentines of the Dashukivka deposit in terms of chemical composition and structure showed their correspondence to widely known analogs but they were never used in such a capacity. According to the results of the tests, the additives have shown their effectiveness as geomodifiers of friction. Addition of 4 % serpentine to the lubricating composition based on I-20 A oil reduced the wear rate by 2–3 times, the friction moment by 15 %, compared to I-20 A without additives. An increase in surface microhardness was observed, from 6 GPa for the basic variant to 10 GPa, for the variant with FGM additives. It has been established that the use is most effective for heavily loaded friction pairs (ship fittings, hatch closures, etc.) as it increases the clamping load (from 600 to 1400 N for a pair of steel 45/ShKh15); with increasing load, the coefficient of friction and the rate of wear decrease. The results confirm the need to expand research into this area to solve the complex problem of increasing the reliability of tribojunctions. Keywords: repair and restoration technologies, friction geomodifiers, serpentine, heavily loaded friction pairs

Compaction of Hydrophobic Molybdenum Disulfide Coatings for Promoting Tribological Behaviors on Engineering Steel

Ambient environment has a crucial effect on the lubrication performance of molybdenum disulfide (MoS2) coatings. In this work, we fabricated porous MoS2 coatings via a facile optimized aerosol-assisted chemical vapor deposition (AACVD) method. It is found that the obtained MoS2 coating demonstrates outstanding antifriction and antiwear lubrication performance with the coefficient of friction (COF) and wear rate as low as 0.035 and 3.4 × 10–7 mm3/Nm in lower humidity (15 ± 5)%, respectively, which is comparable to the lubrication ability of pure MoS2 in vacuum. In addition, the hydrophobic property of porous MoS2 coatings is suitable for infusing lubrication oil to achieve stable solid–liquid lubrication in higher humidity (85 ± 2)%. The composite lubrication system shows excellent tribological behavior in both dry and wet environments, which will alleviate the sensitivity of the MoS2 coating to the environment and ensure the service life of the engineering steel in complex industrial backgrounds.

A test for evaluating the scuffing performance of fully-formulated lubricants

This article presents the development and application of a test method to assess the scuffing resistance of fully-formulated lubricants using the Mini-Traction-Machine 2 tribometer. A barrel-on-disc contact in contra-rotation allows for high contact pressures along with high sliding velocities while maintaining low entrainment velocities. The test method is based on raising the sliding velocity in steps to increase the severity of contact conditions. These steps allow the effect of the lubricant composition on the scuffing performance to be studied. The results include an analysis of the maximum contact temperature and the frictional power intensity at the onset of scuffing.

Preparation and properties of graphene composite lubricants additive used for cylinder liner in marine diesel burning low sulfur fuel oil

In recent years, abnormal wear issues have emerged in cylinder liner-piston rings (CL-PRs) in marine diesels that burn low-sulfur fuel oils (LSFO). To address this issue, a graphene-attapulgite composite additive was prepared and characterized as detailed in this report. Then, the tribological properties and corrosion resistance of this graphene-attapulgite were investigated when it was used at various concentrations as a multifunctional composite lubricant additive in simulated LSFO lubrication conditions. It was found that the appropriate concentration of the additive in a lubricant produced excellent anti-friction and anti-wear properties. This was when the additive was at 0.25 wt% concentration in normal lubricating conditions, where the friction coefficient and wear mass loss were reduced by 22.7% and 44.1%, respectively. Additionally, the impermeability of the graphene additive was found to improve the corrosion resistance of the lubricant. These findings revealed the mechanism of the graphene-attapulgite additive for friction reduction and corrosion resistance of cylinder liner in simulated LSFO lubrication conditions, which provided an inhibition method to prevent abnormal wear of cylinder liner in marine diesel burning LSFO.

Synthesis of ZnFe2O4@MoS2 core-shell nanocomposites with enhanced lubrication performance as lubricant additives

PurposeThe purpose of this study is to prepare ZnFe2O4 nanospheres, sheet MoS2 and three ZnFe2O4@MoS2 core-shell composites with various shell thicknesses, and add them to the base oil for friction and wear tests to simulate the wear conditions of hybrid bearings.Design/methodology/approachThrough the characterization and analysis of the morphology of wear scars and the elemental composition of friction films, the tribological behavior and wear mechanism of sample materials as lubricant additives were investigated and the effects of shell thickness and sample concentration on the tribological properties of core–shell composite lubricant additives were discussed.FindingsThe findings demonstrate that each of the five sample materials can, to varying degrees, enhance the lubricating qualities of the base oil and that the core–shell nanocomposite sample lubricant additive has superior lubricating properties to those of ZnFe2O4 and MoS2 alone, among them ZnFe2O4@MoS2-2 core–shell composites with moderate shell thickness performed most ideally. In addition, the optimal concentration of the ZnFe2O4@MoS2 lubricant additive was 0.5 Wt.%, and a concentration that was too high led to particle deposition and affected the friction effect.Originality/valueIn this work, ZnFe2O4@MoS2 core–shell composites were synthesized for the first time using ZnFe2O4 as the carrier and the lubrication mechanism of core–shell composites and single materials were compared and studied, which illustrated the advantages of core–shell composite lubricant additives. At the same time, the influence of different shell thicknesses on the lubricant additives of core–shell composites was studied.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2022-0367/

A review of solid lubrication based on polyurethane composites

AbstractSolid lubricant materials could be used in various extreme conditions owing to the excellent anti‐friction and ‐wear with the low friction coefficient and wear rate. Polyurethane (PU)‐based solid lubricants as one of the widely utilized composite materials had been well‐known by researchers all over the world. PU‐based composite lubricants were commonly segmented into single‐phase lubricants and multi‐phase lubricants via inorganic or organic lubricant additives. What is more, the modified PU by solid lubricants would endow higher tribological performances than that of single‐phase PU‐based lubricants. Based on the multi‐component synergy, the multi‐phase lubricants could significantly improve the PU matrix's lubrication and wear resistance and enhance the comprehensive performance such as corrosion resistance. This paper mainly discussed and summarized the recent development in tribological performances of PU‐based composite lubricants, and explored their prospective research directions.

Tuning the interfacial behavior of extreme pressure lubrication by stearic acid-modified TiO2 nanoparticles

The development of high-performance lubricants under extreme pressure (EP) is of great significance for reducing energy waste and protecting ecology in heavy industries such as aerospace, large machinery, and so on. Sulfurized isobutylene (SIB) has been explored as one of the most effective EP additives for oil-based lubricants and delivered promising friction-reducing performance. However, the excessive corrosion caused by SIB on the metal surface seriously reduces the instrument’s lifetime and hinders its extensive practical application. Herein, we develop stearic acid-modified TiO2 nanoparticles (SA-TiO2) as a lubricant additive to improve the EP lubrication performance of obtained composite lubricant (CL). During EP friction, the SA-TiO2 can tune the interfacial structure of tribopair and form a high-strength nano-ceramic film to improve tribological performance. Meanwhile, the SA-TiO2 can also compensate for the high wear caused by SIB, thus significantly enhancing the antiwear, friction reduction, and EP properties by 27%, 20%, and 25%, respectively, when compared with the traditional lubricant (TL) obtained by only SIB. Benefiting from the above synergistic effects, the CL can significantly lower the SIB contents while maintaining high EP performance (4900 N weld load). These findings demonstrate a promising eco-friendly lubricant and provide new insights into the mechanism study for EP lubrication.

Mechanism on heterogeneous transfer film formed by diamond-like carbon film under molybdenum disulfide hybrid polyethylene glycol lubrication

Heterogeneous materials are an ideal platform for low friction, but most of the heterogeneous materials used in tribology field are artificially synthesized. Here, by matching the molybdenum disulfide (MoS2) hybrid polyethylene glycol (PEG 200) and diamond-like carbon (DLC) film, the spontaneous formation of heterogeneous transfer film was realized during sliding. Thus, the anti-friction/wear ability of the synergetic system is improved from the reduction of friction coefficient and wear rate by 33.3% and 32.1% contrast to DLC film, severally. The characterization results show that the heterogeneous transfer film is formed by the rehybridization and recrystallization of MoS2 and DLC combined with amorphous phase. The improvement on shearing capacity and bearing capacity of as-designed lubrication strategy better explicates the solid-liquid synergistic effect. The formation theory of heterojunction in solid-liquid composite lubrication is put forward, which has important reference value for the future solid-liquid composite lubrication technology.

Receiving of New Carbon-Sulfur-Containing Plastic Lubricants Based on Regenerated Products and Used Sorbents

The work is devoted to the solution of the actual problem of waste management and its use for obtaining useful technical products, in particular, special purpose plastic lubricants. The research has been conducted on the use of spent sorbents after complex adsorption purification of industrial wastewater from Cu2+, S2– and HS–-ions in the composition of plastic lubricants. The composition of the latter includes a solid modified surface of sorbents [(activated carbon + kieselguhr) + CuS + S] and regenerated industrial oil I-40A. High operational properties of plastic lubricants are provided by modification of the solid surface of the components, on which there are active centers for chemisorption. The surface modification of activated carbon has been carried out in order to obtain [Cu(µ-S5)]2 or CuS2 as possible equivalent substitutes for MoS2. It was established that the chemical interaction of the pentasulfide anion and the copper (II) cation ends with the formation of a planar six-coordinated chelate center CuS4(Н2О)2 on the surface, followed by its destruction and the formation of copper (II) sulfide and elemental sulfur. Activated carbon acts not only as a sorbent, but also as an active catalyst of topochemical reactions on a solid surface. Modification of the kieselguhr surface is caused by the presence of active centers on its surface – silanol groups –OH, which are subject to esterification. The developed plastic lubricants provide the necessary operational properties of heat-resistant industrial lubricants.

MODIFIED POLYALKENYL SUCCINIMIDE ADDITIVE FOR MOTOR OILS

The article is devoted to the synthesis of a chemically modified version of one of the most important additives for the prevention of low-temperature precipitation in engine oils - polyalkenyl succinimide. This additive is prepared by alkylating maleic anhydride with an α-olefin oligomer and then reacting the resulting oligoalkenyl succinic anhydride with various amines. A new compound, an oligomer of hexene-1 with dicyclopentadiene, was used as an alkylating agent, which makes it possible to expand the raw material reserves of oligomeric compounds used in the synthesis of polymer additives, as well as to impart anticorrosive properties to the additive by introducing dicyclopentadiene rings. The composition and structure of the obtained compounds were studied by appropriate physicochemical research methods. The content of 1.5% of the obtained additive in M-11 oil completely eliminates oil corrosion and improves detergent properties. And this allows you to create a lubricant composition with a simpler composition and, as a result, gives an economic effect. The sample of the new additive complies with the requirements for the industrially produced C-5A additive and, in addition to an increased oil viscosity index; it also has anti-corrosion properties, which is due to the chemical structure of the raw material, i.e., the presence of a carbocyclic dicyclopentadiene fragment in the molecule

Development of Technology for Processing Fat Waste into Technical Products

A technology has been developed for obtaining surface-active substances (amides of fatty acids) from the waste of meat processing enterprises. They can be used in the production of detergents, process fluids, lubricant compositions, atmospheric corrosion inhibitors and other operating materials. Tests have shown that the addition of 10% fatty acid amides obtained by waste processing to I-20 base oil can reduce sample wear by 24%.

Microstructure and frictional properties of copper-tin composites containing graphite and MoS2 by rapid hot-press sintering

Rapid hot-press sintering was employed to prepare the self-lubricating composites using Cu-Sn alloy, Cu-coated graphite, and Cu-coated MoS2 powder as raw materials. The effects of the sintering temperature on the microstructure, interfacial characteristics, and friction properties of the composites were primarily examined. The findings demonstrated that as the sintering temperature rose from 680 °C to 780 °C, the copper alloy matrix's grain size grew. The composites' density and hardness increased and subsequently declined as the sintering temperature rose. Moreover, the interfacial bonding between the copper-coating lubricant and the copper alloy matrix was improved by raising the sintering temperature. The average friction coefficient of the composite grew and then fell as the sintering temperature rose, and the wear initially increased, then decreased, and then increased again. The copper-tin composite had good frictional properties because a composite lubricating film made of graphite, MoS2, and metal oxides formed on the worn surface. Among them, the comprehensive friction performance was best at the sintering temperature of 760 °C, with an average friction coefficient of 0.11 and a wear rate of 2.332 × 10−6 mm3N−1·m−1. The wear mechanism was the combined coupling effect of abrasive wear, adhesive wear and oxidative wear.

Development of a pre-screening-method for the qualification of environmentally acceptable lubricants for stern tube systems—The evaluation of friction efficiency and scuffing capacity

Lubricants for stern tube systems are subject to increasingly stringent requirements in terms of environmental compatibility, as any lubricant leakage leads to contamination of the sea. As a result, interest in environmentally acceptable lubricants (EALs) is increasing. Biodegradable ester lubricants represent a possible alternative to conventional, mineral oil-based lubricants. In addition to environmental compatibility requirements, these ester lubricants must also meet tribological requirements. In this study, suitable tribometers were therefore combined in a pre-screening method to cost-effectively test lubricants for their tribological requirements (friction efficiency, wear protection and scuffing capacity). For this purpose, the contact parameters are transferred from the real conditions in the stern tube system’s journal bearing and from the standardized component tests (FZG for gears and FE8 for rolling bearings) to tribological model tests on a Mini-Traction-Machine (MTM, PCS Instruments). The result of the study is a method for the pre-screening of EALs under the application-related journal bearing and standardized component test conditions, respectively. The results show an influence of the lubricant composition on the friction efficiency in fluid friction as well as the transition point from fluid to mixed friction. Furthermore, an influence of the lubricant composition on the scuffing capacity could be shown. The results of friction efficiency and scuffing capacity confirm also a high reproducibility for those pre-screening tests.

Исследование антифрикционных и противоизносных свойств смазочных материалов судового назначения, содержащих слоистый модификатор трения

The paper highlights the results of anti-friction and anti-wear tests of samples of lubricating media containing a layered friction modifier - molybdenum diselenide. The main variable test conditions are the load on the test samples, volume concentration of the layered friction modifier in the lubricating oil, preliminary storage time of the lubricating composition before testing. The main evaluation criteria are the mass wear of samples, wear intensity, friction coefficient. Each of the eight test cycles was implemented on a tribotechnical installation of an original design using a cylindrical contact type. The resource indicators transferred from the model conditions of the tests to the real tribological unit “ring-cylinder” of a marine diesel engine 6ChSP 18/22 were evaluated. According to the results of tribological studies, the effect of increasing the load on the model friction unit of the installation, containing a cylindrical wear pair of alloyed gray cast iron, was revealed, as a result of which the mass wear of the annular movable sample increases, and the resource transferred to the real tribological interface of the marine diesel engine “ring-cylinder” decreases in 1.13-1.23 times. The greatest influence on the wear indicators of model samples and the resource transferred to the real “ring-cylinder” interface of a marine diesel engine is the time of preliminary storage of a lubricant composition containing molybdenum diselenide as an additive. It has been proven that the deterioration of anti-friction properties (an increase in the average surface temperature of a segment sample and the friction force) is largely affected by a decrease in the volume concentration of an anti-wear additive in the oil. It has been found out that serious changes in the indicated estimated parameters are valid for the smallest loading step on the samples. General recommendations are formulated for the use of antiwear additives considered in the studies. It has been proved that storing lubricating compositions with additives is possible for a period of no longer than 3-4 days at given volume concentrations in the range of 0.5-1.0%, since if this period is exceeded by 25-40%, the diesel CPG resource may be halved with increased wear of its piston rings and cylinder liners.