Scuffing Prevention using Lubricants Under High Loads

A driveline and transmission fluid composition that achieves low speed wear and scuffing resistance in heavy-duty applications. The composition includes a base oil, zinc dialkyl dithiophosphate, metal-containing detergents, and a low molecular weight diol or triol compound, with the diol or triol compound being present in an amount of 0.01 to 3.5 weight percent. The composition is particularly suited for use in heavy-duty applications such as off-road equipment and construction machinery, where it provides improved wear protection and scuffing resistance in gear and bearing applications.

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Introducing an additive is a practical approach to improve the lubrication performance of base oil in the field of tribology. Herein, a series of sulfoximine derivatives was synthesized and incorporated into base oil A51 as additives. The tribological properties of these lubricants were evaluated at both room and high temperatures, and the result demonstrated that they displayed excellent friction reduction and wear resistance in the friction process under both test conditions. Moreover, the chemical composition of the worn scar surface was inspected using EDS, XPS and TOF-SIMS to explore the lubricating mechanism. It is reasonable to conclude that the synergistic interaction between the aromatic ring scaffolds and elements like N, F, and S facilitated the adsorption of lubricant on the steel block surfaces and forming a tribofilm during the friction process. This tribofilm has a dominant impact on the systems lubrication performance. This research provides novel oil-soluble lubricant additives, offering a facile approach to formulating high-quality lubricants.

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Lubricating compositions for transmissions, axles, tractors, and industrial gears that achieve desired load carrying capacity while improving copper corrosion performance. The compositions include a thiadiazole additive and a specific type of tris-aryl phosphite compound with a particular ratio of para-position to ortho-position substitution. This combination enables the lubricant to meet performance requirements for load carrying capacity while also preventing copper corrosion.

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A lubricating oil composition for various mechanisms in apparatuses, comprising a base oil, zinc dialkyldithiophosphate, and a sarcosine derivative. The composition provides improved lubrication properties, including seizure resistance and wear resistance, while maintaining fuel efficiency. The zinc dialkyldithiophosphate acts as a metal-based detergent and extreme pressure agent, while the sarcosine derivative enhances lubricity and dispersibility. The composition can be used in applications such as engines, transmissions, and hydraulic systems.

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Abstract Enabling gears to withstand loss of lubrication in gearboxes without secondary oil supply systems can reduce weight and space demand and thus fuel consumption. This study investigates the potential of surface and material technologies on the loss of lubrication performance of gears. Thereby, superfinished, coated, and nitrided gears are compared to ground gears. Systematic experiments under loss of lubrication are performed at a back-to-back gear test rig with circumferential speeds of up to 20 m/s and Hertzian pressures in the pitch point of up to 1723 N/mm 2 . Torque loss, pinion bulk temperatures, and tooth flank surface are analyzed. The results show that surface and material technologies can greatly influence frictional behavior and damage initiation of gears operating under loss of lubrication. With the materials and conditions tested, superfinishing yields to accelerated rise of frictional losses and thus scuffing. Coatings lead to significantly enhanced service life under loss of lubrication by friction reduction and scuffing avoidance.

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Solid lubricants are those materials that are used to lubricate mainly in dry circumstances. Its main role is similar to that of oils and greases, which is used to create a continuous and adherent lubricant film on the tribological pair surfaces for minimising friction and wear [1]. These coatings are typically employed in situations where liquid lubricants cannot be used or do not offer expected lubrication, such as in high or cryogenic temperatures, high vacuum, ultrahigh-radiation, reactive environments and in extreme contact pressure conditions [2]. Different types of solid lubricants, including graphite, have been extensively used since the middle of the 20th century [3]. From 1950 onwards, development in aeronautics industries emphasised the research and development of advanced solid lubricants. They can be classed based on their crystalline structure, features, properties, or functions, among other things. Different types of solid lubricant coating are shown in Fig. 1 [1].

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A lubricant composition for driveline and industrial gears that combines two types of viscosity modifiers with optional esters to achieve improved thermal stability, traction performance, and efficiency. The composition comprises a hydrocarbon lubricating base stock and a viscosity modifier composition that includes an olefin polymer and a grafted olefin copolymer. The combination of these viscosity modifiers enables the lubricant to maintain its performance characteristics at lower viscosities, while also providing improved traction and reduced friction.

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Abstract Today, mineral or synthetic oils that are made out of fossil raw materials are the most common lubricants in gear drive applications. Most of them are nonbiodegradable and may pose a risk to the environment. An important step to minimize the risk and the ecological footprint is the use of biodegradable and eco-friendly lubricants. Former research shows the potential of water-based lubricants in gear applications. Therefore, an oil-free, water-based lubricant was developed for this study. The base lubricant contains plant-based thickeners to generate an appropriate viscosity for a sufficient lubricant film thickness in the tooth contact. In experimental investigations, the sliding wear and scuffing performance has been examined under variation of the added polymers and additives. The scuffing tests A/8.3/RT are performed according to DIN ISO 14635-1. The wear test procedure is based on DGMK 377-01. In both scuffing tests with the sample, the failure load stage = 8 was achieved. For case-carburized gears, a medium to high amount of wear can be detected. Additional tests wi... Read More

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In mechanical systems, lubricants play a crucial role in minimizing friction, dissipating heat, and preventing wear. Additives, comprising both organic and inorganic compounds and typically constituting 0.1% to 30% of lubricant volume, are introduced to enhance lubricant performance. This study investigates the influence of various additives on lubricant behaviour and performance, encompassing antifoam agents, corrosion inhibitors, antioxidants, detergents, extreme pressure additives, pour-point depressants, and viscosity index improvers. Friction coefficients were meticulously measured using a pin-on-disk tribometer to assess the Tribological and physical properties of these additives. Surface analysis via SEM provided insights into wear characteristics influenced by the additives. The comprehensive tribological assessment reveals that the incorporation of additives consistently reduces friction and wear across different base oil types. This underscores the critical role of additives in improving lubricant properties, maintaining thermal stability, and forming protective films on su... Read More

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An anti-wear and anti-friction lubricating oil additive comprising malic acid, fatty alcohol, malic acid ester, and maleic acid ester, wherein the additive generates graphite-like carbon structures in situ at the friction contact interface to reduce friction coefficient and wear. The additive can be formulated with malic acid (0.5-20 wt%), fatty alcohol (5-50 wt%), malic acid ester (0.1-80 wt%), and maleic acid ester (0.2-50 wt%). The additive can be prepared by ultrasonication or stirring with a lubricating oil base oil.

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Transmission fluid composition for heavy-duty applications, comprising a base oil, a molybdenum-containing component, a zinc dialkyldithiophosphate, and a calcium detergent. The composition provides bearing pitting protection while meeting the static friction requirements of the Caterpillar TO-4 specification.

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Under high-temperature, high-speed, heavy-duty, and extreme lubrication operating conditions, such as those found in gearboxes of aviation engines and electric vehicles, gear scuffing failure has emerged as a critical issue and a primary technical challenge in the mechanical transmission field. As test methodologies, evaluation criteria, and load-carrying capacities related to gear scuffing are yet to reach full maturity in response to these demanding operating environments, this article examines existing literature on gear scuffing failure and its control, incorporating insights from industry practices and academic studies. The discussion encompasses the development of gear scuffing theories, experimental investigations, and practical applications, ultimately providing an overview of the most recent developments in gear anti-scuffing technologies. The ultimate goal of this work is to elucidate failure mechanisms of gear scuffing and establish effective design approaches for gear anti-scuffing.

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Modern engines are designed for very close contact between shearing planes, which requires high-performance boundary lubrication, delivered by lubricant base oils formulated with an array of additives. Commercial additive packages...

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The objectives of this chapter are to: (i) Define the term lubricants and identify, outline and discuss the principal types of lubricants; (ii) Identify, outline and describe the three typical inorganic compound kinds that could be employed as solid lubricants; (iii) Identify, outline and discuss those significant properties of commercial fluid lubricants; (iv) Identify, outline and discuss the reasons the effectiveness of the lubricating oil deteriorates over time or requires replacement after some time of usage; (v) Outline and discuss the lubricating oil selection and materials for tribological applications; (vi) Define the term additives and outline their roles and functions within lubricants; (vii) Identify, outline and describe the commonly used additives; (viii) Outline and discuss the tribology of rolling elements and applications; and (ix) Analyse, derive and discuss the power absorbed to overcome the viscous resistance due to the lubricating oil's viscosity in rolling bearings, such as journal, foot-step and collar bearings.

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Experimental gear scuffing results were obtained in the FZG test rig for wide ranges of the applied torque, tangential speed, base oil viscosity and bath oil temperature, and for FZG type A and type C gears.A scuffing criterion for gears lubricated with base mineral oils was developed, proposing the existence of gear mass temperatures which are critical for each lubricant (viscosity grade).The scuffing criterion shows very good correlation with experimental results.The dynamic viscosity of the oils at those critical mass temperatures is constant that permits the determination of other critical temperatures for other gear mineral oils without need additional scuffing tests.

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Wear mitigation in gears and rolling bearings lengthens the service life of machines and contributes to the achievement of a more sustainable society. Organic additives form protective films on rubbing steel surfaces of mechanical contacts that can mitigate wear significantly. However, wear prevention requires the design of new additives for lubricants that are environmentally friendly. Molecular simulations are employed to investigate the effect of the base oil on the adsorption, the lubricant adhesion, and structural properties of a promising organic additive (N,N - Bis(4-aminobutyl) oleylamine). Results are compared with oleylamine. They suggest better performances for the promising organic additive. Overall, findings further support the fact that additives with polar head groups with aminoalkyl branches reduce wear efficiently in mechanical contacts.

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This study explored the potential enhancement of lubrication performance by incorporating polydimethylsiloxane (PDMS) powder as a lubricant additive.

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Lubricant additives can effectively enhance the performance and environmental adaptability of lubricants and reduce the energy loss and machine wear caused by friction. Nanomaterials, as important additive materials, have an essential role in the research and development of new lubricants, whose lubrication performances and mechanisms are not only related to their physical and chemical properties, but also influenced by the geometric shape. In this paper, the friction reduction and antiwear performances of nanomaterials as lubricant additives are first reviewed according to the classification of the dimensions, and their lubrication mechanisms and influence rules are revealed. Second, the recent research progress of composite nanomaterials as lubrication additives is introduced, focusing on their synergistic mechanism to improve the lubrication performance further. Finally, we briefly discuss the challenges faced by nanoadditives and provide an outlook on future research. The review expects to provide new ideas for the selection and development of lubricant additives to expand the ap... Read More

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Lubricant is used to decrease wear on two surfaces that come into contact with each other, and additives can aid to improve the lubricant's performance. Engine oil is the lubricant that we use in combustion engines, and ex-ternal additives that are available on the market can be added to the engine oil to improve its performance. The purpose of this study is to see how ex-ternal additives affect the tribological performance of engine lubricants. The performance of three lubricant samples was investigated in this study: commercial engine oil (SAE10W-30), engine oil mixed with friction modifier additives, and engine oil mixed with anti-wear and extreme pressure additives. The mixtures' viscosity, coefficient of friction (COF), and wear scar diameter (WSD) were determined using viscometer, four-ball tester, and high-performance microscope. The findings show that the mixes behave differently than commercial oil. Even though adding additives to engine oil is sup-posed to boost performance, the flash temperature parameter (FTP) deter-mined from WSD, and the frictional behaviour a... Read More

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Lubricants play a critical role in the energy losses of an engine. Several engineering solutions are existing to reduce the frictional and wear losses caused by the lubricant such as ultra-low-viscosity lubricants. With the spread of low-viscosity engine oils like 0W-20 and below, the importance of tribological lubricant additives is increasing. To ensure the necessary protection of the rubbing surfaces against friction and wear, new lubricant additive materials should be researched and investigated. Next to the tribological performance of the additives, their impact on the price is a strong influencing factor. No financial information of the investigated additive materials is available in the current scientific articles and so no rentable decision can be defined which additive worth to invest as an engine oil additive in the future mass production engine oils. This article presents the tribological potential of selected nanoscale ceramic particles (zirconia, cupric oxide and yttria) as lubricant additives and compares them according to their financial impact. According to the result... Read More

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. The article considers the issues of creating a lubricating composition which is an internal complex salt and possesses anticorrosive properties along with thermal oxidative stability. Antifriction and anti-wear properties of the additive were investigated, the wear of parts in friction units was reduced by 3.2-7.5 times within the normal force range of 73.15-115.15 kgf.

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Lubricating oil can effectively reduce friction between mechanical parts, thereby reducing energy consumption and improving service life and reliability. Due to the development of science and technology, it is necessary to improve the performance of lubricating oil to fulfill the higher tribological requirements for countering wear and providing lubrication. Nanolubricant additives have the four lubrication mechanisms of micro-bearing, protective film, polishing, and repair effects. A nanolubricant additive can often demonstrate a variety of lubrication mechanisms at the same time. As lubricating additives, metal and metal oxide nanoparticles have outstanding effects which improve the tribological properties of lubricating oil and have been widely studied in the field of tribology. This paper introduces the lubrication mechanism of nanoadditives and the latest research results for metal and metal-oxide nanoparticle lubrication additives.

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A lubricant composition that provides wear and seal protection in gear lubrication applications, comprising an oil of lubricating viscosity and about 0.01 to about 5 percent by weight of a substantially sulfur-free alkyl phosphate amine salt. The salt contains at least about 30 mole percent of phosphorus atoms in an alkyl pyrophosphate salt structure, with at least about 80 mole percent of the alkyl groups being secondary alkyl groups of about 3 to about 12 carbon atoms. The amine portion is a hydrocarbyl amine that is a hindered hydrocarbyl amine, an aromatic hydrocarbyl amine, or a combination thereof.

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Effective lubrication between rubbing surfaces is required to reduce friction and wear. Conventional lube oils traditionally contain a package of additives that significantly improve their tribological properties. Antiwear and load-carrying additives improve boundary lubrication and reduce wear of the rubbing surfaces due to the formation of quasi-liquid crystalline layers on them [1]. Such structured layers with molecular ordering determine the tribological characteristics of the friction units

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The paper presents the results of studying the lubricity of several lubricating compositions, two of which contain an antiwear additive based on a layered friction modifier - molybdenum diselenide. Oil MC-20, which does not contain functional antiwear additives, is used as a base lubricating medium and an object of comparison. Two variants for combining an antiwear additive with this oil differ in the process of initial preparation of the additive before adding it to the base lubricating oil by rotary pulsation grinding and stirring. Antiwear tests are arranged in the form of a consistent tribological rating of the given types of lubricating media at various operating time of the friction path of the test samples. The test tool is a rotary-type friction machine of an original design. There are analyzed the differences in the antiwear test methodology and the advantages of the proposed scheme over the analogous one, which is relevant for GOST R 51860-2002. Among the results of the tribological study carried out, topographic patterns of wear of test specimens, the dependence of the wea... Read More

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Scuffing is becoming a quite common failure mode in gears and bearings. It has been shown that AW/EP additives are effective in preventing scuffing, but only if they are able to form a thick tribofilm before encountering severe scuffing-type conditions. This study has employed a contra-rotating, step-sliding speed scuffing test to explore the impact of PMAs on the ability of ZDDP and a commercial SP additive-containing package to prevent scuffing when subjected to immediately severe conditions. It is found that some PMAs can greatly enhance the anti-scuffing performance of these AW/EP additives. They do this by forming thick, adsorbed boundary films that can withstand high speed sliding conditions and protect the rubbing surfaces long enough for tribofilms to form.

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Lubricating oil is known as "the blood to maintain the normal operation of machinery", and additives are an indispensable and important part of lubricating oil. In this paper, the Polymer-based Composite Nano-additive (PCNA) suitable for armored vehicle engine lubricating oil was developed, the physical and chemical properties of lubricating oil containing additives were carried out. The results showed that adding an appropriate amount (3 vol.%) of additives could improve the low-temperature fluidity of lubricating oil and improve the kinematic viscosity of lubricating oil without affecting the viscositytemperature characteristics of lubricating oil. The four-ball testing machine, high temperature end face testing machine and engine bench are used to measure the anti-friction lubrication effect and anti-wear ability improvement effect of the additive on lubricating oil. The experimental results show that the additive can effectively improve the antifriction, lubrication and anti-wear performance of lubricating oil. In addition, the addition of the additive can effectively improve the... Read More

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An increase the level of its combat readiness, reliability and durability of fi re tighting can be ensured, among other things, through the use of high-performance lubricants in friction units of fi re trucks. The use of a metal-cladding additive for lubricants to improve their antiwear properties. The procedure for conducting tribotechnical tests is described. The results of tribotechnical tests of oil modifi ed by the developed additive are presented. The results obtained indicate a positive effect of the metal-cladding additive on the antiwear properties of the test oil.

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Abstract General reductions in lubricant viscosities in many machine components mean that the role of lubricant additives in forming tribofilms has become increasingly important to provide adequate surface protection against scuffing. However, the relationship between scuffing and the formation and removal of tribofilms has not been systematically demonstrated. In this study, a step-sliding speed scuffing test based on contra-rotation using MTM-SLIM and ETM-SLIM has been employed to observe concurrently tribofilm thickness and the onset of scuffing. The initial sliding speed used was found to significantly affect scuffing performance since it determines the extent to which a tribofilm can form before critical sliding speed conditions are reached. In general, additives that formed thicker tribofilms, especially ZDDPs and triphenyl phosphate, gave effective protection against scuffing, though their protective tribofilms were progressively removed at higher sliding speeds, eventually resulting in scuffing. Graphical Abstract

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A lubricant composition that provides good wear and seal protection in gear lubrication applications, while minimizing the negative impact on seal materials. The composition contains a phosphorus-based antiwear additive that is low in sulfur and contains a "seals-friendly" amine component that can neutralize acidic components in the lubricant without compromising seal tensile strength and elasticity. The additive is particularly effective in low-viscosity lubricant formulations and can be used in a wide range of mechanical devices, including gears, axles, and manual transmissions.

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Lubricating oil composition for drive system apparatus comprising a base oil and a phosphorus-containing compound represented by the general formula (1): R1-R2-R3-P(=O)-O-R4, wherein R1, R2, R3, and R4 are independently selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, and aralkyl groups, and the phosphorus-containing compound is blended in an amount of 0.1 to 5.0% by mass.

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Lubrication for extreme conditions, such as high temperature, cryogenic temperature, vacuum pressure, high load, high speed, and corrosive environments, is a continuing challenge among tribologists and space engineers due to the inadequate friction and wear properties of liquid lubricants. As a result, tremendous research effort has been put forward to study lubrication mechanisms for various machine elements under challenging conditions over the past two decades. Self-lubricating materials have been most widely used for adequate lubrication in extreme conditions in recent years. This review paper presents state-of-the-art of materials for lubrication in extreme condition applications in aerospace, automotive, and power generation areas. More specifically, solid lubricants dispersed in various matrices for lubrication application were analyzed in-depth under challenging conditions. This study also reports the self-lubricating materials and their lubrication mechanisms. Finally, various applications and challenges of self-lubricating materials were explored.

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A lubricant composition comprising an oil of lubricating viscosity and 0.01 wt % to 15 wt % of a protic acid salt of an N-hydrocarbyl-substituted gamma-(γ-) or delta-(δ-) amino(thio)ester, wherein the amino group is separated from the ester group by a chain of at least 3 carbon atoms. The composition provides improved wear performance, reduced corrosion, and enhanced seal compatibility in mechanical devices.

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A lubricating composition for driveline devices that provides improved wear resistance, friction performance, and deposit control. The composition contains an oil of lubricating viscosity, a non-borated dispersant, a detergent, and an antiwear package comprising a derivative of a hydroxycarboxylic acid, an amine salt of a phosphoric acid ester, and a phosphite having at least one hydrocarbyl group with 4 or more carbon atoms. The composition is particularly effective in manual transmissions and gearboxes, where it provides improved synchronizer performance and reduced wear on gear teeth and bearings.

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In most gear drive applications mineral or synthetic oils are used as lubricants, which are made of fossil raw materials and are non-biodegradable. In applications located in critical environmental areas such as boats or harbors, eco-friendly lubricants are needed. As a result, a gear transmission fluid based on water is currently being developed in a research project supported by the Bayrische Forschungsstiftung (Bavarian Research Foundation). Results of former research showed that in general it is possible to use water-based lubricants in gear drives under certain operating conditions. Since water has a low viscosity compared to conventional used lubricants, plant extracts are added to generate higher viscosities. In order to avoid tribological influenced damages such as sliding wear and scuffing on the surface of gear flanks, adequate additives are needed. Different combinations of plant extracts and additives were investigated using the scuffing test A/8.3/RT according to DIN ISO 14635-1. The results show a surprisingly high load carrying capacity regarding scuffing. Additionally... Read More

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The issues of increasing the reliability and durability for fi re trucks the use of highly effi cient lubricants in friction units of machines, improving the antiwear properties of hypoid oils used to lubricate the gear wheels of the main drive in transmissions of the trucks are considered. An antiwear additive based on soft metal stearates is proposed. The results tribotechnical tests of the developed antiwear additive, which indicate the effectiveness of its application, are presented.

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The use of appropriate lubricant additives can reduce surface damage, extend machine lifetimes, improve machining accuracy, and reduce power consumption. In this study, the effects of zinc dialkyl dithiophosphates (ZDDP) additives in lubricating oil on the tribological performance, vibration characteristics, and scuffing thermal mechanism were experimentally investigated using a four-ball tribotester. The impact of the running-in process with ZDDP-containing lubricants on scuffing resistance was examined by varying the applied normal loads. The results showed that the addition of ZDDP and presence of the running-in process could effectively increase the scuffing load, which is in good agreement with previous research. This paper further describes the factors breaking the energy equilibrium caused by scuffing, including the lubricant temperature, friction, vibration, and wear particles. For different weight percentages of the ZDDP in the running-in and step-loading processes, the difference in wear curves was relatively small. The decrease in the number of large particles (>1 m) befo... Read More

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The article is devoted to the analysis of the most used additives for lubricants. The principle of their operation and the result of their work are considered. The effect of additives on the structure of surface layers on the surface of friction pairs is est imated. The analysis showed the use of only a limited number of principles of the action of antifriction additives. Theoretically promising antifriction additives for base oils, relevant for use in railway transport, have been proposed.

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Lubricants supports hydrocarbons with variety of mixtures and do not satisfy all necessities in fashionable applications. The numerous researchers have tried to minimize the friction and wear co-efficient of lubricants by improving its tribological properties. One of the approaches is by including additives within the base lubricants to alter its properties. Tribological characteristics of high refined mineral derived engine oil of different grades were studied by adding nano particles. The trials were conducted by varying the applied load and percentage concentration of nano particles in the lubricants. Pin on Disc Tribo tester was utilized to determine the co-efficient of wear and friction.

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Abstract A high load carrying capacity regarding micropitting is requested in many modern gear applications. The lubricant used has a great influence on the micropitting resistance of a gear-lubricant-system. As a result, it is highly recommended that a lubricant with a sufficient micropitting load-carrying capacity be used to avoid micropitting. Lubricants usually contain additives, which also have a strong effect on micropitting load-carrying capacity depending on operating temperature. As a result, the load-carrying capacity of gear lubricants cannot be determined theoretically and has to be determined by physical testing. A well-established test procedure to determine load-carrying capacity with regard to micropitting is the FVA/FZG-micropitting test according to FVA 54/7, which is also the basis of the recently published standard DIN 3990-16. This test method was defined about 30 years ago with standardized test gears, which differ from gears commonly used in modern applications. Therefore, the practicability of the test method needs to be reviewed and the suitability of the tes... Read More

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In an automotive application it is necessary to use the lubricants between the contacting/ moving surfaces. The world is suffering from the lack of mineral based lubricating oil and the hick in price as well as mineral oil based lubricants effect the environment also. The vegetable oil based lubricants become the good alternate of the mineral based oils due to its biodegradability, zero green-house effect and non-toxicity behaviour. In this review different types of vegetable oils are studied and the comparative studied also done between the oils. The thermo-physical parameters, velocity index and other properties of the oil are also considered. The use of additives and the nanoparticles additives are also considered in this paper. The nanoparticles additives enhance the lube properties of base oil due to which the more reduction in friction and wear are observed.

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A transmission fluid composition for manual transmissions that provides wear protection and frictional properties. The composition comprises a major amount of lubricating oil basestock and a minor amount of an additive package containing a mixture of phosphorus-containing compounds, a molybdenum compound, and optionally ashless dispersants, detergents, and antioxidants. The additive package provides synergistic wear protection and frictional properties that enable efficient gear shifting and reduced wear in manual transmissions.

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Lubricating oil compositions with improved wear control and energy efficiency for mechanical components like gears, bearings, and transmissions. The compositions have a unique blend of low and high viscosity base stocks. The high viscosity base stock is present in a small amount to control film thickness, while the higher concentration low viscosity base stock controls traction coefficient. This allows using a low bulk viscosity oil with improved film properties for wear prevention. The blending approach enables enhanced wear protection and efficiency by leveraging the solubility of the base stocks to phase separate under extreme lubrication conditions.

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Biodegradable gear lubricant composition that meets industrial and marine performance standards while being non-toxic and non-bioaccumulative in the environment. The composition comprises anti-wear and extreme pressure additives, antioxidants, and other performance-enhancing components that provide superior tribological properties and seal compatibility.

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A lubricant composition for mechanical devices that improves wear protection over a wide temperature range. The composition contains an oil of lubricating viscosity, a sulfur-free alkyl phosphate amine salt antiwear additive, and either a hydrocarbyl amine salt of an alkylphosphoric acid ester, a glycerol ester, or a mixture thereof. The composition provides improved wear protection in gears, axles, and bearings at temperatures from 40°C to 160°C.

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Lubricants are an important part of any tribological system [...]

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Loss of lubrication (LOL) in a rotorcraft transmission causes erratic degradation of drivetrain components due to direct surface contact thereby increasing the frictional heat in the system. This article studies the ability of synthetic and mineral-based lubricating oils typically used in the aviation industry regarding their physical properties, chemical composition, and detailed chemical structure to extend the longevity of the rotorcraft transmissions in the event of LOL. The lubricating oils were subjected to boundary lubrication tests using a FZG gear test rig and two lab-scale tribometers, cylinder-on-ring and ball-on-disc. The results provide an enhanced ranking of the selected lubricating oils based on their load-carrying capacity and scuffing resistance under LOL conditions complemented by the consideration of the oil chemistry.

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Friction and wear loss of various machining parts and pairs depend majorly on the quality of lubricants. Several types of additives are commercially used to enhance the tribological performance of a lubricant. In the present work, some novel lubricating liquids were prepared by mixing diffident additives, viz bromide, fluoride, iodide and acetate, in a commercial available SAE20W40 lubricant. Pin-on-disc investigations were performed to evaluate the effect of the prepared lubricants on wear rate and friction characteristics of mild steel and stainless steel sliding pair. Disc chamber was flooded with lubricants during testing. Fluoride was found to be the most successful additive to improve the performance of the given lubricant, whereas acetate as an additive made the base lubricant less efficient. It is believed that the strong bond stability of CF bond during working conditions resulted in better performance of the lubricant after the addition of fluoride.

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Nanomaterials have emerged as potential environment friendly lubricant additives to upgrade the conventional lubricants such as automotive oils, industrial oils, grease, and metal working fluids. The applications of nanoparticle additives are based on the principles of solid lubrication and are mostly used as anti-wear, anti-friction and extreme pressure additives. Their various advantages include small enough size, thermal stability, variety of particle chemistries and a high reaction rate with the surface without induction period. These advantages translate into longer equipment operation, increased fuel efficiency and extended maintenance intervals. Thus, the current article designates on the benefits/advantages of nano materials as lubricant additives and their applications in various automotive/engine/industrial oils. Further, it covers on (a) the major types of industrial oils and their key properties/functions and (b) different nanomaterials that are currently being explored as lubricant additives, their thermal stability and technical challenges.

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Growing environmental concern is shifting lubricant markets towards synthetic products, which demonstrate better tribological performance than their mineral oil counterpart. Research on potential economic savings stemming from energy wasted through excessive friction and wear estimates the total global energy consumption could be reduced by 8.7% by 2032. As a byproduct, CO2 emissions stemming from friction and wear deficiencies could be reduced by 35%. The least understood lubrication regime (boundary lubrication) is the major culprit for energy loss, and for this reason, remains a hot topic within a vast interdisciplinary research community. After covering the fundamentals of lubrication, this series of studies explores the lubricant properties of organic and inorganic lubricant additives synthesized for the purpose of mitigating friction and wear under boundary lubrication. First, a biolubricant derived from a novel yeast source is investigated. This is followed by two additional studies which explore the tribological properties of organic additives, specifically synthesized esters... Read More

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