Low Viscosity Lubricant for Higher Temperature Conditions

Bearings are common components used in the transmission system of tool machinery and linear drive equipment.With increasing demand for higher efficiency and faster production under the required accuracy, the control of bearing temperature rise under high operational speed becomes a critical issue.The improper control of temperature rise can lead to the thermal deformation and life reduction of the machinery.Conventionally, a circulating oil lubrication system is utilized with journal bearings.In this study, a similar lubrication system was adopted for the ball bearing with a retrofit design.Three control factors, i.e., rotational speed, bearing preload, and the viscosity of the lubricant used, were chosen to study their effects on the temperature performance of the proposed lubrication system.Experimental measurements showed that the lubrication system was able to lower the temperature rise of the bearing considerably compared with its unlubricated counterpart, especially at high rotational speeds.Even with the enhanced cooling from the oil circulation system, temperature rise still ... Read More

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Bio-lubricants are the future of lubricants as a substitute for mineral lubricants; however, bio-lubricants have drawbacks, such as poor thermal-oxidative stability. In addition, during the friction process, the temperature of the lubricant increases, so the lubricant must have good thermal conductivity to conduct heat to the environment. To combat the drawbacks of bio-lubricants, some additives have been used to improve their performance as lubricants. Composites of carboxymethyl cellulose (CMC)/MXene and Span 60 as surfactants were used as additives in CPO with different compositions. The physicochemical properties of the addition of CMC/MXene and Span 60 in CPO have changed, including kinematic viscosity, TAN, thermal conductivity, and fatty acids, which have a positive impact on lubrication performance in terms of reducing oxidation processes and increasing thermal conductivity. From fatty acid composition tests and FTIR analysis, the additives work to suppress the oxidation process. A pin-on-disk test was performed to evaluate the tribological performances of bio-lubricants. The... Read More

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Controlled vacuum environments as in space applications represent a challenge for the lubrication of tribological components. In addition to common space lubricant requirements like, e.g., low evaporation, a broad operational temperature range and a high stability during operation, long-term-storage (LTS) properties have gained increasing attention recently. The term addresses the time-dependent stability of a lubricant under static conditions, which can mean chemical degradation processes such as oxidation on the one hand, but also the physical separation of oil and thickener in heterogeneous lubricants like greases. Due to the extended storage periods of lubricated components on-ground but also during a space mission for several years, it has to be ensured that a lubricant is still functional after LTS. This article depicts the development of a space lubricant grease with LTS properties. Firstly, LTS requirements and methods for their assessment are discussed. In the following, a systematic approach towards the design of a grease formulation compatible with LTS is described. Finall... Read More

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Lubricating compositions that maintain viscosity stability and prevent oxidative degradation when contaminated with biodiesel, comprising a base oil, sulfurized additives, boronated dispersants, and a detergent system with a specific sodium-to-magnesium ratio and sulfur-to-sodium ratio. The detergent system provides a controlled level of soap content and metal ions, while the sulfurized additives and boronated dispersants contribute to oxidative stability. The composition is particularly effective in preventing viscosity increase when contaminated with up to 30% biodiesel, as demonstrated by passing the GFC Lu-43-A-11 test.

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One of the main characteristics of lubricants is the viscosity index, which shows the dependence of oil viscosity on temperature. The higher the viscosity index, the better the lubricating properties of the oil. Esters of various polyols, in particular pentaerythritol, are very effective in this direction. This work examines a wide range of high-purity pentaerythritol esters of 14 compounds of varying degrees of branching and studies the temperature dependences of kinematic viscosity in the temperature range from melting temperatures to 150C. Based on the obtained data, the values of viscosity indexes were calculated, and the contribution of the carboxylic acid structure to the viscosity properties was also considered.

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As countries prioritize climate change concerns, promoting the use of new environmentally friendly working fluids has become a common goal for the industry. In thermal systems, lubricants come into contact with these working fluids and directly affect their utilization efficiency. Therefore, investigating the effect of lubricant mixing on the physical properties of process media is essential to promote the adoption of new environmentally friendly working fluids. This paper categorizes and organizes recent research literature on working fluids and lubricants. It was aimed to comprehend the effect of lubricants on the operating characteristics of working fluids. By comparing the research methods and experimental equipment utilized in previous studies, this work analyzes the variation of basic physical properties, including miscibility, solubility, viscosity, and gas-liquid phase equilibrium. In addition, the effects of lubricant mixing in terms of heat exchange characteristics, additives, and material compatibility are also summarized. These findings provide a reference for achieving o... Read More

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ABSTRACT Lubricants play a crucial role in reducing friction and wear between surfaces in relative motion. Engine oil, as a lubricant, is specifically designed to minimize friction and wear between the moving parts of different equipment and machinery. Engine oil blending serves the purpose of adjusting the variety of lubricants available to meet specific performance requirements. Through blending, it is possible to tailor the characteristics of the lubricating oil, such as viscosity, stability, and additive content, to optimize its effectiveness in reducing friction, protecting engine components, and enhancing overall equipment performance. By customizing lubricant formulations through blending, manufacturers can address the diverse lubrication needs of modern engines and machinery, ensuring smooth operation, longevity, and efficiency.To enhance the quality of the lubricant and achieve the desired high-performance multi-grade engine oil, a systematic approach was followed. The process began with testing the specific gravity of the oil using a hydrometer and thermometer to ensure acc... Read More

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Achieving appropriate miscibility, solubility, and working viscosity between a lubricating oil and a refrigerant is vital for proper compressor performance. These properties are all interrelated and cannot be optimized independent of one another; the thermodynamics that define one interaction also influence the others. Choosing the best fluid combination is therefore a tradeoff between the different properties, making it critically important to understand their possible behaviors. This paper will investigate the range of liquidliquid miscibility behaviors and explore the resulting solubility and working viscosity outcomes. Different lubricant chemistries will be tested to demonstrate the impact of lubricant chemical family on performance, as well as looking within a chemical family to show how finely tuned chemistry choices can shift test results. The outcome from this investigation will help compressor engineers design more reliable and energy-efficient systems.

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Abstract Most studies of liquid lubricants were carried out at temperatures below 200 C. However, the service temperature of lubricants for aerospace and aeroengine has reached above 300 C. In order to investigate the friction mechanism and provide data for high temperature lubrication, the friction and wear properties of chlorophenyl silicone oil (CPSO)-lubricated M50 steel and Si 3 N 4 friction pairs were investigated herein. Ball-on-disk experimental results show that the lubrication performance of CPSO varies significantly with temperature. Below 150 C, coefficient of friction (COF) remains at 0.130.15 after the short running-in stage (600 s), while the COF in the running-in stage is 0.20.3. At 200 C and above, the running-in time is much longer (1,200 s), and the initial instantaneous maximum COF can reach 0.5. Under this condition, the COF gradually decreases and finally stabilizes at around 0.160.17 afterwards. This phenomenon is mainly due to the different thickness of boundary adsorption film. More importantly, the wear rate of M50 steel increases significantly with t... Read More

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When exposed to high surface temperatures, engine lubricating oils degrade and may form solid deposits, which cause operational issues and increase shutdown time and maintenance costs. Despite its being a common issue in engine operation, the information available on the mechanics of this phenomenon is still lacking, and the experimental data and conditions must be updated to match the improvements in both lubricant stability and engine efficiency. To this end, an experimental apparatus has been developed to study the mechanisms that lead to the degradation and deposit formation of lubricants at high temperatures. The apparatus is designed to operate at pressures up to 69 bar, surface temperatures up to 650 C, oil bulk temperatures up to 550 C, and flow rates of <14 mL/min. In this apparatus, the oil is cycled through a heated test section, and deposits accumulate on the heated surface. The time required for deposits to start accumulating under the test conditions is determined based on the recorded temperature traces, and collected oil and deposit samples may be analyzed to... Read More

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The paper presents the results of studies aimed at defining the effect of the cooling properties of oil lubricants used in various metalworking processes. The design and a brief description of the installation are given, which allows to obtain temperature-time, temperature-velocity dependencies of various liquids. The use of this installation gives the opportunity to select lubricants according to its cooling properties, depending on the temperature range required by the process. The assessment results of lubricant cooling properties at UZS-2 installation, manufactured according to the requirements of international standards ISO 9950, ASTM D6200 - 01 and ASTM D6482 06 are presented. The dependences of tribo-engineering properties of the tested oil lubricants on their cooling characteristics are found out. It is shown that with an increase in the temperature at which the maximum cooling rate of the lubricant is provided, its extreme pressure and anti-wear properties determined according to GOST on a four-ball friction machine increase.

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Viscosity improvement property of a lubricant additive is commonly attributed to polymer coil expansion with increasing temperature, although only some polymer chemistries show conformance to this conceptual mechanism. Herein, we show that the polarity of base oil governs whether this mechanism underlies the action of a viscosity modifier (VM) by combining experimental and computational studies. Poly(butyl methacrylate) (PBMA) dissolved in diethylene glycol diethyl ether (DGDE) or a mixture of DGDE (polar solvent) and squalane (SQ, nonpolar solvent) was used as a model lubricant oil system. Specific viscosity of the polymer solutions measured over a wide range of additive concentrations and temperatures revealed that thickening efficiency of the VM decreased with decreasing base oil polarity. While the VM counteracted temperature-induced thinning of the low polarity base oil, in the polar solvent, the polymer did not enhance the solution viscosity at higher temperatures. Aiming to unravel the molecular mechanism underlying viscosity improvement at elevated temperatures in the differe... Read More

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The key function of lubricants is to reduce the friction, wear, and heat between the parts that are in contact with each other. The main applications of the lubricants are to control temperature, and reduction in wear and corrosion of the machinery. Keeping in mind the importance of lubrication and its applications in varied machines. The goal of this research is to inspect the heat transmission impact in the magnetohydrodynamic flow of Jeffrey liquid near a stagnation point through a lubricated surface. Lubrication is accomplished by a shear-thinning liquid. The velocity, continuity, and shear stress, amalgamated with power-law fluids, are used to develop interfacial conditions. The exclusivity of the anticipated model is the inclusion of variable thermal conductivity and diffusion coefficients in the existence of homogeneous-heterogeneous reactions. Using the KellerBox finite-difference approximation approach, the numerical results are accomplished. The outcomes are portrayed and tabulated in the form of diagrams and tables, respectively. It is witnessed that a greater magnetic fi... Read More

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Viscosity-index improving agent for lubricating oils that provides improved low-temperature viscosity, high-temperature high-shear viscosity, and gelation index. The agent comprises a copolymer containing a polyolefin-based monomer, a C4-alkyl-substituted monomer, and at least one of a C2-C3-alkyl-substituted monomer or a C4-alkyl-substituted monomer, along with an ester oil. The copolymer is present in a range of 10-70 wt% and the ester oil in a range of 0.01-5 wt% of the total agent weight.

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<div class="section abstract"><div class="htmlview paragraph">The purpose of this study is to investigate how the kinematic viscosity of lubricating oil used in hybrid electric vehicle (HEV) and electric vehicles (EV) transaxles affects thermal conductivity and gear seizure resistance. This study investigated the relationship between viscosity, thermal conductivity and gear seizure resistance in detail and found that thermal conductivity tends to decrease with decreasing viscosity. It was also found that the thermal conductivity decreases significantly after a certain viscosity. The relationship between viscosity and gear seizure resistance was also investigated and it was found that too low a viscosity causes a significant deterioration in gear seizure resistance.</div></div>

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Grease composition for lubricating applications like gears that provides stable grease supply and retention. The grease has a base oil of polyalphaolefin (PAO) and a soap thickener. It has a viscosity transition stress of 300 Pa or more at 25°C to penetrate contact areas, but less than 40 Pa at 100°C to prevent grease migration. Shear viscosities at 25°C and 100°C are also optimized to balance grease supply and retention.

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Lubricants play a central role in many technical applications, e.g. in bearings and gears as well as in machining processes. In such applications, lubricants are exposed to extreme conditions in the contact area. In lubrication gaps, the pressure can reach values up to 5 GPa. The thermophysical properties of lubricants, and in particular the viscosity, at such extreme conditions have an important influence on the friction and wear behavior of a tribosystem. Accordingly, reliable lubricant property models are a prerequisite for accurate tribological simulations, e.g. elastohydrodynamic lubrication (EHL) simulations. Presently, the vast majority of experimental thermophysical property data are only available up to 1 GPa. Thus, reliable and robust models with strong extrapolation capabilities to higher pressure are required. In this work, viscosity measurements of squalane in a temperature range be tween 20 C and 100 C and pressures up to 1 GPa were carried out. Based on that data, a physical model for the viscosity was developed. The model is built by combining a molecular-based equa... Read More

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Reducing the viscosity of the lubricant is an effective way to improve the energy efficiency of automobiles. However, designing a lubricant with the desired properties requires elucidating the relationship between viscosity and molecular structure. In this study, we measured the temperature dependence of the dielectric relaxation of model lubricants with different molecular structures. Dielectric relaxation measurements were used to evaluate the influence of ambient viscosity on the motility of single molecules. In addition, we measured the temperature dependence of the lubricant viscosity using a rotational viscometer. By comparing the flow viscosity and dielectric relaxation measurement results, we showed that the activation volume and energy of the luburicant, which determine viscosity, can be resolved. As a result, we succeeded in quantitatively evaluating the contribution of molecular structure to changes in the activation energy, and elucidated the effect of the density of polar groups per molecule on changes in the activation volume.

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The relation with viscosity and pressure of lubricant has been considered in detail from the past. Barus equation that was presented in 1893 is known as the basic equation. This paper describes the new linear viscosity equation, that included dimensionless density and temperature other than pressure as functions in comparison with Barus equation. Author measured high pressure viscosity by using reciprocating-piston type test apparatus and measured high pressure density by using capacity type test apparatus in each temperature and pressure. After that, author attempted to derive the density into Barus equation and it was found that dimensionless density was preferable as density. Furthermore, author attempted to introduce temperature into Barus equation. It became able to in this way deal with the new viscosity equation as a linear equation. It found out that the logarithm of dimensionless viscosity was proportional to pressure and it was inversely proportional to temperature and dimensionless density cubed. And it was found that these slope of lubricants by this linear equation are... Read More

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Lubricant has an important function in protecting the parts of an engine where to minimise the wear formation on the surface between two moving parts. The mixing of lube oil SAE10W-30 Petronas oil and Shell oil may have caused an effect to the wear stability of the lubricant. The aim of this study is to determine the behaviour of the oils viscosity, COF and WSD of the ball using the FBM. The experiment was done under different speed and the mixture was rested. Based on the analysis, the viscosity is thinning as the temperature gets high. The thinnest oil is 20% Shell mixture and 5% Shell is the thickest but viscosity was not affected by the rested time. COF has decreased as the speed increased. However, longer resting period did not give any effect as the speed higher but has increased COF. The WSD was increased by the higher concentration of Shell as well as the speed. Overall, different concentration of Shell oil and rested time has an effect on the lubricity performance.

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