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A. Shalwan, Talal Alajmi i Naser Alajmi. "Study on the tribological performance of bio-lubricant conditions- Review". Global Journal of Engineering and Technology Advances 16, nr 2 (30.08.2023): 001–11. http://dx.doi.org/10.30574/gjeta.2023.16.2.0125.
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The products based on fossil oils are increasing with the concerns of the environmental sectors and academics as well. In this era, there are challenges to finding alternative resources replacing fossil oil for different engineering applications. One of the fossil oil products is lubricant. Fossil lubricants have many industrial applications and involve millions of dollars each year in the development of lubricants due to their huge needs. Accordingly and to satisfy the industrial needs with the environmental considerations, alternative environmentally-friendly-Lubricants are nowadays the main aim identity by the tribologists. The main objective of this work is to investigate the usage of vegetarian oils as lubricant. For that , many bio-lubricants based on vegetable oil were studied and investigated the influence of these oils on wear and frictional characteristics of adhesive wear. Also, the results are very encouraging to candy the bio-lubricant as an alternative to synthetic oils any many industrial applications.
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Surakasi, Raviteja, Ravi Ganivada i Ramya Pakalapati. "Study Comparing the Tribological Behavior of Cottonseed and Castor Oil Biodiesel Blended Lubricant under varying Load Conditions". International Journal for Research in Applied Science and Engineering Technology 11, nr 4 (30.04.2023): 4047–55. http://dx.doi.org/10.22214/ijraset.2023.51178.
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Abstract: We have an increasing global need for bio lubricants that are safe for human and environmental use, easily biodegradable, and non-polluting. The friction and wear qualities of cotton seed blended lubricant as well as castor blended lubricant are compared and contrasted in this research using a Pin on disc wear testing Tribometer. In this research, we will look at the study's results and analyse their significance. Blended lubricants were created by combining cotton seed & castor based biodiesel with the basic lubricant SAE20W40 at volumetric ratios of 5, 10, 15, & 20%. Cotton seed and castor blended bio lubricants were tested for friction and wear at sliding velocities of 2.5 metres per second while subjected to weights of 50 N, 100 N, and 150 N. Wear might be slowed by as much as 15 percent by mixing in cotton seed biodiesel with the base oil, as has been shown. When this threshold is passed, wear increases at an ever-increasing pace. Castor oil blended lubricant performed best in wear tests when coupled with a base lubricant at a 5 and 10 percent castor oil blended lubricant concentration. The wear rate was accelerated when 15 percent castor oil was added to the basic lubricant. It has been discovered that at lowest and maximum load, CBL 5 and CBL 10 may serve as an alternative lubricant to increase mechanical efficiency at a sliding velocity of 2.5 metres per second. Because of their efforts, less need has been seen to lessen dependence on petroleum-based goods.
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Djordjević, Milan, Vesna Mandić, Srbislav Aleksandrović, Vukić Lazić, Dušan Arsić, Ružica R. Nikolić i Zvonko Gulišija. "Experimental-numerical analysis of contact conditions influence on the ironing strip drawing process". Industrial Lubrication and Tribology 69, nr 4 (10.07.2017): 464–70. http://dx.doi.org/10.1108/ilt-05-2016-0113.
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Purpose The purpose of this paper is comparison of experimental values of the drawing forces to numerical values in different contact conditions, taking into account the appearance of galling which occurs due to of difficult drawing process conditions. Design/methodology/approach The following two research approaches are used in this paper – the physical modeling, realized by the laboratory experiment, and the numerical simulation of the ironing drawing process. By analyzing the obtained results, the technique of physical modeling, with help of the laboratory equipment and numerical simulation by application of the finite element method, can be successfully used in studying the thin sheet ironing – strip drawing process. Findings It is significant to compare values of the deformation forces obtained by physical experiment to values obtained by the numerical simulation. In that way, it is possible to compare applied contact conditions (four lubricants in that case) and estimate matching of experimentally and numerically obtained results of the deformation forces. Presented results point out very good technological characteristics of ecologically friendly lubricant (single-bath) and grease based on MoS2. Significant decrease of the deformation force was achieved by its application, as well as maintaining of the lubricant’s layer during the forming process and almost complete elimination of galling on the contact. Practical implications Numerical analysis of stresses in the working piece wall, during the thin sheet strip drawing, requires precise values of the friction coefficient. It is an important indicator because one can define the contact conditions as the input data for the numerical simulation, based on its values for each type of lubricants and each value of the compressive lateral force. Originality/value The environmentally friendly lubricant tested exhibits a more favorable distribution of the drawing force during the process, mainly in experimental case. Grease based on MoS2 has good lubricating properties but that lubricant is conventional and environmentally unacceptable. Ecologically friendly lubricant can be successfully used in real ironing strip drawing process especially for high values of holding force achieving an increased tool life.
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Streator, J. L., B. Bhushan i D. B. Bogy. "Lubricant Performance in Magnetic Thin Film Disks With Carbon Overcoat—Part I: Dynamic and Static Friction". Journal of Tribology 113, nr 1 (1.01.1991): 22–31. http://dx.doi.org/10.1115/1.2920599.
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Static and dynamic friction coefficients are presented for an Al2O3·TiC slider in contact with 130 mm carbon-coated rigid thin film disks lubricated with several different perfluoropolyether lubricants. The lubricants tested include three nonpolar liquid lubricants and one polar liquid lubricant with dihydroxyl end groups. The effects of lubricant film thickness, disk surface topography, sliding speed and lubricant viscosity are investigated. In many cases, the interfaces exhibited a sharp increase in the dynamic and static friction coefficients after a certain film thickness was reached, due to strong adhesion in the interface. In most cases, the lubricant thickness for the onset of high friction forces was found to increase with increasing disk surface roughness, lubricant viscosity and sliding speed. Under certain conditions stick/slip of the slider occurred during which the static friction increased with time of contact. The various data suggest that the rate at which strong adhesion develops depends on the lubricant viscosity.
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Glazunov, D. V. "Development of the lubricant for side-mounted rail flange lubricators for traction rolling stock". Vestnik of the Railway Research Institute 78, nr 1 (13.05.2019): 59–64. http://dx.doi.org/10.21780/2223-9731-2019-78-1-59-64.
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Specificity of operating conditions of the rolling stock defines a number of requirements for lubricants intended for the wheel-rail tribosystem. Lubricants are used for “wheel — rail” contact, the aggregate state of which varies from liquid to solid. When evaluating the lubrication properties of these materials, a significant number of factors must be taken into account, in particular, influence of the environment, method of application, condition of the rail surface. The paper discusses the main operational requirements for lubricants operating in a wheel-rail tribosystem. Temperature ranges of the lubricants used for the “wheel — rail” contact on the railway network of the Russian Federation are given. As a result of the research, it was determined that none of the materials used for lubrication of the wheel-rail system satisfies the operating temperature conditions of the traction rolling stock. To solve this problem a lubricant was developed and tested in an industrial environment at the Rostov State University of Railway Transport. Its lubricant composition allows to significantly expand the temperature range of the lubricant. Complex of experimental studies and method of orthogonal central composite plan of the 2nd order established the optimum values of the thickness of the working shell of the 0.846 mm lubricating rod and the 50.411 % percentage of plastic lubricant, allowing to extend the temperature range of lubricant rods and, in particular, completely eliminate the lubricant flow to achieve a temperature of 126.034 °C. Proposed composition of the lubricant was tested on a freight electric locomotive of the VL80T series, equipped with non-power lubricators, under the conditions of the Bataysk — Likhaya section of the North Caucasus Railway. Intensity of wear of the wheel flanges of the traction rolling stock lubricated by the proposed material, compared with the intensity of wear of the wheel flanges without the use of lubrication systems is reduced by 2 times.
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Rodríguez Leal, Bárbara, Justine Decrozant-Triquenaux, Jens Hardell i Leonardo Pelcastre. "Development of a Laboratory-Scale Test Methodology for Performance Evaluation of Lubricants for Hot Stamping of an Aluminium Alloy". Lubricants 11, nr 9 (23.08.2023): 359. http://dx.doi.org/10.3390/lubricants11090359.
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In hot stamping of aluminium, the need for efficient methods to evaluate, compare, and rank lubricants based on their tribological performance is critical in the early stages of selection. Pilot and simulative testing can be costly, time-consuming, and complex, making it inefficient for initial benchmarking. This work aims to develop a test methodology to assess lubricant performance for hot stamping under key operating conditions without fully simulating the forming process. The proposed method distinguishes the impact of temperature on lubricant degradation, friction, wear response, and cleanability. The tests utilised a conventional hot work tool steel and a 6010S aluminium alloy with two commercially available lubricants: a polymeric lubricant and a lubricant containing graphite. The tribological tests involved a reciprocating, sliding flat-on-flat configuration at two temperatures (100 °C and 300 °C). The methodology showed that the graphite-containing lubricant exhibited over a four times lower friction coefficient than the polymer-based lubricant at 10 wt.% concentration and 300 °C. At 100 °C, both lubricants provide lubrication and can be cleaned, but increasing temperature led to a significant decline of both aspects. The observed temperature range where the lubricants degrade was between 120 °C and 170 °C.
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Bak, Mun-Gyu, Jong-Sung Won, Seon-Woong Koo, Arom Oh, Han-Ki Lee, Dae-Sik Kim i Seung-Goo Lee. "Migration Behavior of Lubricants in Polypropylene Composites under Accelerated Thermal Aging". Polymers 13, nr 11 (25.05.2021): 1723. http://dx.doi.org/10.3390/polym13111723.
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The surface migration of lubricants degrades the quality of thermoplastic polymer composites. In this study, the surface migration of lubricants in polypropylene composites were studied to improve the quality of the composites. Polypropylene (PP)/lubricant composites were manufactured using a co-rotating twin-screw extruder and injection molding, and the migration phenomena of the lubricant in the PP/lubricant composites were investigated under accelerated aging conditions with temperatures in the range of 20 to 90 °C and humidity of 100% for 72 h. The interrelation between the surface migration properties of PP/lubricant composites were investigated by considering their microstructural and morphological features, which were influenced by the thermal aging conditions. Further, the microstructural and morphological features were examined by contact angle, surface energy, attenuated total reflectance Fourier-transform infrared spectrometry, X-ray photoelectron spectroscopy, close-up digital imaging, and atomic force microscopy analyses. The polypropylene composites containing the magnesium stearate as the lubricant were found to exhibit a more stable migration behavior than the polypropylene composites containing a calcium stearate lubricant. This is attributed to multiple synergistic factors, such as interfacial tension and work of adhesion between PP and the lubricant. The findings of this study can be utilized to effectively manufacture high-quality thermoplastic composites for the fourth industrial revolution.
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Devlin, Mark. "Common Properties of Lubricants that Affect Vehicle Fuel Efficiency: A North American Historical Perspective". Lubricants 6, nr 3 (3.08.2018): 68. http://dx.doi.org/10.3390/lubricants6030068.
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The development of advanced lubricants to improve vehicle fuel efficiency can appear to be as simple as lowering the viscosity and frictional properties of a fluid. However, applied research studies have shown that it is quite difficult to quantify the fuel efficiency properties of advanced lubricants in vehicles. A review of the historical research predominantly performed in North America in this area reveals that there are many factors to consider in order to demonstrate the effectiveness of advanced lubricants. First, the methodology used to measure vehicle fuel efficiency will impact the results since there are many factors not related to the lubricant which will influence vehicle fuel efficiency. Second, developing advanced fuel-efficient lubricants under well controlled conditions overlooks the issue that lubricant properties such as viscosity and friction affect the operating conditions encountered by the lubricant in the vehicle. Finally, the physical properties of lubricants that historically control fuel economy do not have the same effect on fuel efficiency in all vehicles. The proper vehicle or system level test needs to be selected to properly assess the benefits of new advanced lubricants.
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Jung, Yeonjin, i Changdong Yeo. "Mechano-Chemical Properties and Tribological Performance of Thin Perfluoropolyether (PFPE) Lubricant Film under Environmental Contaminants". Lubricants 11, nr 7 (21.07.2023): 306. http://dx.doi.org/10.3390/lubricants11070306.
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Through molecular dynamics (MD) simulations with ReaxFF potential, the effects of chemical contaminants on the mechano-chemical properties and tribological performance of perfluoropolyether (PFPE) lubricants were investigated. For the two types of contaminants, i.e., silicon dioxide (SiO2) nanoparticles and water (H2O), their molecular interactions with the two different PFPE lubricants, i.e., Ztetraol and ZTMD, were evaluated at the two different temperatures, i.e., 300 K and 700 K. Contaminants were adsorbed onto the PFPE lubricants at a controlled temperature. Then, air shear simulations were conducted to examine the mechano-chemical behaviors of the contaminated lubricants. Sliding contact simulations were performed to further investigate the tribological performance of the contaminated lubricants, from which the resulting friction and surface contamination were quantified. Lastly, chemical reactions between PFPE lubricants and contaminants were studied to investigate the degradation of PFPE lubricants. It was observed that SiO2 nanoparticles stiffened the PFPE lubricant, which decreased its shear displacement and increased friction. In the case of the H2O contaminant, it weakened and decreased the PFPE lubricant’s viscosity, increasing its shear displacement and lowering friction. However, the decreased viscosity by H2O contaminants can weaken the lubricity of the PFPE lubricant, leading to a higher chance of direct solid-to-solid contact under high contact force conditions.
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Chandran Suja, Vineeth. "Challenges in Mitigating Lubricant Foaming". Lubricants 10, nr 6 (1.06.2022): 108. http://dx.doi.org/10.3390/lubricants10060108.
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Lubricant foaming and its mitigation is an active area of research driven by demands from modern machinery that require foam-free lubricant operation over extended periods and under adverse conditions. Tackling lubricant foaming has proven to be challenging due to interdependent foam stabilization mechanisms and a multitude of antifoam inactivation routes. This perspective briefly outlines the key challenges faced by researchers in this field. Overcoming these challenges to create lubricants with superior foaming characteristics requires the development of new lubricant and antifoam chemistry as well as a shift from the existing trial-and-error methods to mechanistic-insight-driven lubricant formulation and antifoam design.
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Carré, D. J. "Perfluoropolyalkylether lubricants under boundary conditions: Iron catalysis of lubricant degradation". Journal of Synthetic Lubrication 6, nr 1 (kwiecień 1989): 1–15. http://dx.doi.org/10.1002/jsl.3000060102.
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Lee, Sung-Jun, Yoon-Chul Sohn i Chang-Lae Kim. "Friction and Wear Characteristics of Polydimethylsiloxane under Water-Based Lubrication Conditions". Materials 15, nr 9 (2.05.2022): 3262. http://dx.doi.org/10.3390/ma15093262.
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In this study, the friction and wear characteristics of polydimethylsiloxane (PDMS) were evaluated when using lubricants created by adding surfactants at various ratios to deionized (DI) water. When pure DI water is used as a lubricant, the repulsion of water from the hydrophobic PDMS surface is large and the interfacial affinity is low; thus, the lubrication properties cannot be significantly improved. However, when a lubricant with a surfactant is added to DI water, the interfacial affinity with the PDMS surface increases to form a lubricating film, and the friction coefficient is greatly reduced. In this study, under dry and pure DI water conditions, severe wear tracks were formed on the PDMS surface after 10,000 cycles of reciprocating sliding motion under a vertical load of 100 mN, whereas in the case of the surfactant-based and water-based lubricant, no severe wear tracks occurred. The friction and wear characteristics of the PDMS were evaluated by increasing the normal loads and sliding cycles with a water-based lubricant containing 1 wt % surfactant. Under normal loads of 300 mN and 500 mN, only minor scratches occurred on the PDMS surface up to 10,000 and 100,000 cycles, respectively, but after 300,000 cycles, very severe pit wear tracks occurred.
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Zhang, Y., i K. T. Ramesh. "The Behavior of an Elastohydrodynamic Lubricant at Moderate Pressures and High Shear Rates". Journal of Tribology 118, nr 1 (1.01.1996): 162–68. http://dx.doi.org/10.1115/1.2837073.
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Knowledge of the behavior of lubricants over a wide range of pressures and shear rates is fundamental to an understanding of elastohydrodynamic (EHD) lubrication. The mechanical properties of elastohydrodynamic lubricants have been measured by a number of researchers under the conditions of low pressures and low shear rates, as well as under high pressures and high shear rates. This paper presents experimental results for the synthetic lubricant 5P4E subjected to moderate pressures (60 MPa to 700 MPa) and high shear rates (105 s−1) using the technique of pressure-shear plate impact. Thin layers (25 μm thick) of the lubricant are confined between two hard elastic plates; the assembly is subjected to impact by a parallel plate in a manner designed to induce both compression and shear loading. For approximately 1 μs the compressed lubricant is subjected to a simple shearing motion; during that time, continuous records of the shear stress and shear rate are obtained using laser interferometry. Three test configurations were used in order to cover the pressure range, and special techniques were developed for preparing the specimen sandwich. The pressure range covered includes both the liquid and glassy states of the lubricant. The results show that a limiting shear stress model is an appropriate model for lubricant behavior under these conditions. The experimental results also show little change in the lubricant shearing behavior across the glass transition.
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Kramer, Philipp, i Peter Groche. "Friction Measurement under Consideration of Contact Conditions and Type of Lubricant in Bulk Metal Forming". Lubricants 7, nr 2 (28.01.2019): 12. http://dx.doi.org/10.3390/lubricants7020012.
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The tribological system plays a critical part in designing robust and efficient cold forging operations. The appropriate selection of lubrication allows to forge defect-free workpieces with high dimensional precision and desired surface finish while ensuring that no defects, such as cracks or seams, occur. Additionally, friction and wear are highly affected by the choice of tribological system, which in turn influence the cost-effectiveness of the forging operation by preventing premature tool failure. Next to the employed tool coating and work piece material, the lubrication system and work piece surface topography are the main factors influencing the aforementioned constraints when designing efficient forging operations. In order to choose the appropriate tribological system before implementing it within an industrial forging operation, tribometers are used to characterize the performance of the tribological system. In this paper, the necessity to account for not only the tribological loads when designing these tribometer tests as is typical for existing methodologies, but also for process and lubricant specific properties will be highlighted. With the help of the tribometer sliding compression test, it will be shown that using liquid lubricants necessitates the need to account for the escape of lubricant, while this is not true for solid lubricants. The escape of lubricant from the contact zone is governed by lubricant properties as well as the contact kinematics and may lead to significantly different results regarding friction and wear. In order to account for this escape, the tribometer test must be specifically designed to reproduce the contact kinematics of the investigated industrial forging operation.
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Srikiran, S., K. Ramji i B. Satyanarayana. "Performance Profiling of Nanoparticulate Graphite Powder as Lubricant in the Machining of AISI 1040 Steel under Variable Machining Conditions". Advanced Materials Research 984-985 (lipiec 2014): 15–24. http://dx.doi.org/10.4028/www.scientific.net/amr.984-985.15.
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The generation of heat during machining at the cutting zone adversely affects the surface finish and tool life. The heat at the cutting zone, which plays a negative role due to poor thermal conductivity, resistance to wear, high strength at high temperatures and chemical degradation can be overcome by the use of proper lubrication. Advancements in the field of tribology have led to the use of solid lubricants replacing the conventional flood coolants. This work involves the use of nanoparticulate graphite powder as a lubricant in turning operations whose performance is judged in terms of cutting forces, tool temperature and surface finish of the work piece. The experimentation revealed the increase in cutting forces and the tool temperature when the solid lubricant used is decreased in particle size. The surface finish deteriorated with the decrease in particle size of the lubricant in the nanoregime.Keywords-Turning, Solid lubricant, Graphite, Minimum Quantity Lubrication, nano–particles,Weight percentage,Frictioncoefficient.
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García-Miranda, J. Santos, Luis Daniel Aguilera-Camacho, María Teresa Hernández-Sierra i Karla J. Moreno. "A Comparative Analysis of the Lubricating Performance of an Eco-Friendly Lubricant vs Mineral Oil in a Metallic System". Coatings 13, nr 8 (27.07.2023): 1314. http://dx.doi.org/10.3390/coatings13081314.
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Eco-friendly lubricant research continues to increase since it has a comparative performance to commercial mineral lubricants to overcome the effects of environmental impact. However, the efficiency of these green lubricants depends on specific applications. In this study, we analyzed the friction and wear performance of a castor/sesame oil mixture as an eco-friendly lubricant and its comparison to a commercial mineral lubricant tested in a metallic system employed in bearing elements. For this purpose, AISI 8620 steel against ISO 100Cr6 was used as tribological pair. The friction and wear tests were carried out through a Tribometer of ball-on-disk configuration under boundary lubricating conditions, whereas the worn surfaces were investigated by using optical and electron microscopy. The physical properties and the rheological properties of the lubricants were also determined. The friction and wear performance between the eco-friendly lubricant and mineral oil were similar so that the CLE were comparable. The CLE values in terms of friction and wear ranged from 86% to 99.4%, respectively.
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Syahrullail, Samion, Shunpei Kamitani i Kenji Nakanishi. "The Effect of Lubricant Viscosity in Cold Work Forward Extrusion". Applied Mechanics and Materials 554 (czerwiec 2014): 291–95. http://dx.doi.org/10.4028/www.scientific.net/amm.554.291.
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In cold work extrusion, lubricants play an important role in lubricating the tool and workpiece surfaces, preventing metal-to-metal contact and reducing sliding friction, so that the workpiece can be extruded smoothly without severe wear due to lubricant starvation. In this paper, the influence of lubricant viscosity in cold work forward extrusion was investigated. The lubricants were additive-free, paraffinic mineral oil, which may have low, medium or high viscosity. The workpiece material was pure aluminum A1100, extruded with extrusion ratio of 3. The analysis focused on extrusion force, workpiece surface roughness after the extrusion process and the metal flow in the deformation zone of the workpiece. Using the visioplasticity method, the sliding velocity was calculated from the metal flow. Results showed that, the higher the lubricant viscosity, the lower the extrusion force generated. However, a high-viscosity lubricant produces coarser workpiece surface conditions after the extrusion process.
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Suryawanshi, Shubham Rajendra, i Jayant T. Pattiwar. "Tribological performance of commercial Mobil grade lubricants operating with titanium dioxide nanoparticle additives". Industrial Lubrication and Tribology 71, nr 2 (11.03.2019): 188–98. http://dx.doi.org/10.1108/ilt-04-2018-0147.
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Purpose The purpose of this study is to investigate the tribological performance (anti-friction and anti-wear properties) of commercial Mobil grade lubricants used in a journal bearing system in a power plant. Design/methodology/approach Three grades of Mobil lubricants (DTE 24, DTE 25 and DTE 26) are considered during the study. Titanium dioxide nanoparticles (TiO2, 0.5 Wt.%) of size 40 nm are used as a lubricant additive to examine the performance of the lubricants. The viscosity of the lubricant is computed using modified Krieger–Dougherty viscosity model. The morphology of TiO2 nanoparticles is studied with the help of scanning electron microscopy, ultra violet spectrophotometer and X-ray diffraction. The study of antifriction and antiwear properties for lubricants is carried out on four-ball tribo-tester for operating conditions specified by ASTM standards. Findings The tribochemical reaction film is formed between ball surfaces during the experiments on four-ball tester that minimizes the asperity contact due to addition of TiO2 nanoparticles in the lubricant. The viscosity of the lubricant is enhanced due to the addition of TiO2 nanoparticles. The frictional coefficient and wear scar diameters of balls in the lubricants are reduced in the range of 6-26 and 2-7 per cent, respectively. Originality/value The tribological properties of TiO2 as a lubricant additive in three commercial Mobil grade lubricants are investigated in this paper. The results obtained in this paper are expected to be helpful to bearing designers, researchers and academicians concerned with the relevant study.
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Li, Weimin, Cheng Jiang, Nan Xu, Rui Ma i Xiaobo Wang. "Tribological properties of polyol-ester-based lubricants and their influence on oxidation stability". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, nr 6 (13.09.2018): 823–30. http://dx.doi.org/10.1177/1350650118799546.
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Unlike oxidative degradation of lubricants, tribology-induced degradation is rarely studied. In this work, the tribological performance and oxidative stability of ester-based lubricants were evaluated before and after tribological testing. Results showed that the tribological performances of base oils are highly dependent on the lubricant formulation and test conditions. Tribological processes could cause detrimental effects on oxidative stability even under moderate conditions. The addition of antiwear additives seems to effectively inhibit the chemically breakdown of esters by forming a protective film. Mechanical shearing, high temperature in contact zones, catalytic effect of nascent surface, wear debris, as well as self- catalysis are the major reasons that are responsible for the oxidative deterioration of the lubricant after tribological testing.
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Żaba, K., P. Kita, M. Nowosielski, M. Kwiatkowski i M. Madej. "Influence Of Lubricants On Wear Resistance Of Aluminum Alloy Strips Series 2XXX". Archives of Metallurgy and Materials 60, nr 3 (1.09.2015): 1833–38. http://dx.doi.org/10.1515/amm-2015-0313.
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Abstract The article presents a properly planned and designed tests of the abrasive wear resistance 2024 aluminum alloy strips under friction conditions involving various lubricants. Test were focused on the selection of the best lubricant for use in industrial environment, especially for sheet metal forming. Three lubricants of the Orlen Oil Company and one used in the sheet metal forming industry, were selected for tests. Tests without the use of lubricant were performed for a comparison. The tester T-05 was used for testing resistance to wear. As the counter samples were used tool steel - NC6 and steel for hot working - WCL, which are typical materials used for tools for pressing. The results are presented in the form of the force friction, abrasion depth, weight loss and coefficient of friction depending on the lubricant used and the type of counter samples. The results allowed for predicting set lubricant-material for tools which can be applied to sheet metal made of aluminum alloy 2024.
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Kobayashi, A., N. Unno i T. Yonemoto. "Study on the Adhesion Force of Lubricants—Adhesion Force Characteristics Under Boundary Lubrication". Journal of Tribology 119, nr 1 (1.01.1997): 107–11. http://dx.doi.org/10.1115/1.2832443.
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The mechanisms that generate adhesion forces in liquid lubricants are studied under various experimental conditions. These forces occur between two surfaces when they are detached in the normal direction under static boundary lubrication conditions. The adhesion force is not influenced by the speed at which the upper specimen is pulled up, but is influenced by the viscosity of the lubricant. The adhesion force under boundary lubrication is much greater than that under hydrodynamic lubrication, and it is closely related to the compressibility of the lubricant.
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Carre´, D. J., P. D. Fleischauer, C. G. Kalogeras i H. D. Marten. "Comparison of Lubricant Performance in an Oscillating Spacecraft Mechanism". Journal of Tribology 113, nr 2 (1.04.1991): 308–12. http://dx.doi.org/10.1115/1.2920621.
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A life test of lubricants for the R2 shaft bearings of a spacecraft oscillating scanner mechanism was performed under simulated orbital conditions. The lubricant originally used in the application, a chloroarylalkylsiloxane (CAS) oil, and a linear perfluoropolyalkylether (PFPE) oil failed in less than 2500 hr of operation. A poly-alpha-olefin (PAO) oil has been running for more than 11,000 hr without any indication of lubricant or system degradation. The performances of the oils are discussed in terms of the boundary lubrication conditions of the test.
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Tian, Yuting, Yan Li, Xia Lei i Qihang Li. "Study on Effect of Hot Rolling Process Lubricant on Rolling Force and Thickness of Q235A Strip Steel". Journal of Physics: Conference Series 2553, nr 1 (1.08.2023): 012013. http://dx.doi.org/10.1088/1742-6596/2553/1/012013.
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Abstract 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.
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Lorenz, Robby, Hinnerk Hagenah i Marion Merklein. "Experimental Evaluation of Cold Forging Lubricants Using Double-Cup-Extrusion-Tests". Materials Science Forum 918 (marzec 2018): 65–70. http://dx.doi.org/10.4028/www.scientific.net/msf.918.65.
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Cold forging processes enable the economical production of high quality components like joints, shafts and gears. The manufactured parts are characterized by improved properties such as hardness, surface quality and fatigue strength. For manufacturing components using cold forging, a comprehensive knowledge regarding the cold forging procedure and its process parameters is needed. One important influencing factor, which needs to be analyzed to use the potential of this kind of processes, is the tribological system, especially the used lubricant. The tribological conditions significantly influence the material flow and thus the workpiece quality. Furthermore, resource efficient and environmentally benign metal forming processes became very important within the last decade. The present study evaluates the resulting tribological conditions and their differences for various cold forging lubricants with and without a zinc phosphate based lubricant carrier. The lubricants are based on molybdenum disulphide, polymers, or both inorganic salts and waxes. The tribological conditions of the different lubricants are investigated using the Double-Cup-Extrusion-Test (DCET) as a laboratory friction test.
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Gunda, Rakesh Kumar, i Suresh Kumar Reddy Narala. "Electrostatic high-velocity solid lubricant machining system for performance improvement of turning Ti–6Al–4V alloy". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 233, nr 1 (19.04.2017): 118–31. http://dx.doi.org/10.1177/0954405417703432.
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In any machining operation, a major division of energy is converted into heat which creates detrimental effects on tool wear, tool life and surface quality of machined work material. Effective cooling/lubrication in the machining zone is essential to improve friction and temperatures by efficient heat dissipation which increases tool life and surface quality. But adverse health effects caused by use of flood cooling are drawing manufacturers’ attention to develop methods for controlling occupational exposure to cutting fluids. In demanding the improvement of productivity and product quality of machining, use of solid lubricant thin film was suggested as one of the necessary alternative machining techniques to apply lubricants effectively to the high-temperature zone. There is a general concern in the machining process in terms of applying lubricants effectively to the machining zone. Therefore, this research work contributes to the development of a novel approach to apply lubricants effectively to the rake face and flank face of the cutting tool without polluting the environment. Electrostatic high-velocity solid lubricant assisted machining is a novel technique used in the machining process with a very low flow rate (1–20 mL/h) to enhance the process performance of turning difficult-to-cut materials. The performance of electrostatic high-velocity solid lubricant technique is studied in comparison to minimum quantity solid lubricant, minimum quantity lubricant and dry and wet (flood cooling) to assess the performance considering surface roughness, cutting force and tool wear as performance indices. The experimental results revealed that electrostatic high-velocity solid lubricant with MoS2 solid lubricant at low volume and constant flow rate has observed high potential to apply lubricants effectively in the machining zone when compared with the considered environmental conditions. This work is expected to form a scientific basis toward developing electrostatic high-velocity solid lubricant technique for reducing the manufacturing impact in the machining of aerospace components such as Ti–6Al–4V alloy in terms of both machinability and environmental perspectives.
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Kumar, Rajneesh, i Suresh Verma. "Effect of micropolar lubrication in non-circular hole-entry hybrid journal bearing with constant flow valve restrictor". Industrial Lubrication and Tribology 68, nr 6 (12.09.2016): 737–51. http://dx.doi.org/10.1108/ilt-07-2015-0097.
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Purpose In the present scenario of high-speed machines, the use of non-circular hole-entry bearing configuration, i.e. two-lobe, multi-lobe, lemon bore, etc., has becomes unavoidable, as the journal bearings with non-circular configurations provide better stability at high operating speed and heavy dynamic loading. Further, this research aims to show that the presence of micro particles in the lubricants greatly affects performance of the bearings, as their presence leads to non-Newtonian behaviors of the lubricant. Therefore, to consider the effect of these micro particles, the lubricant is modeled as a micropolar lubricant. The present work analyzes the effect of these micropolar lubricants on the performance of hole-entry circular and non-circular (two-lobe) hybrid journal bearings compensated with constant flow valve restrictor and compares with that of Newtonian lubricants. Design/methodology/approach The modified Reynolds equation governing the laminar flow of iso-viscous, incompressible micropolar lubricant in the clearance space of a journal bearing system has been solved using finite element method and appropriate boundary conditions. Further, a comparative analysis between circular and non-circular (two-lobe) hybrid journal bearing compensated with constant flow valve restrictor operating with Newtonian and micropolar lubricant has been presented. Findings The numerically simulated results reveal that the non-circular bearing configuration provides better performance vis-à-vis the circular bearing configuration. Further, the increase in the micropolar effect of the lubricant enhances the performance of circular and the non-circular bearing configurations compared with the Newtonian lubricant. Also, in the case of the non-circular bearing configuration with an offset factor (δ = 1.5), the bearing performance improved compared with (δ = 1.25). Originality/value Many research studies have been done in the area of non-circular hybrid journal bearing with Newtonian lubricants with different types of restrictors, but the non-circular hole-entry constant flow valve-compensated hybrid journal bearing operating with the micropolar lubricant has not been analyzed. Therefore, in the present work, an effort has been made to fill this research gap.
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KOWALEWSKI, Piotr, i Maciej PASZKOWSKI. "THE INFLUENCE OF KINEMATIC CONDITION AND LUBRICANT PROPERTIES ON FRICTION IN COMPLEX SLIDE–ROLL MOTION". Tribologia 289, nr 1 (31.03.2020): 41–48. http://dx.doi.org/10.5604/01.3001.0014.0842.
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The paper presents the results of preliminary studies into the influence of selected lubricants (greases) and the variable temperature of the friction joint on the value of friction during complex slide-roll motion. The experiment was carried out for three different types of lubricants: bentonite grease (Benterm 2), lithium grease (GREASEN ŁT4S2), and calcium grease with the addition of graphite (GREASEN GRAFIT) at different temperatures. Tribological investigations were carried out in a roller-plate system at a wide range of plate dislocation velocities and at a constant slip rate; rheological investigations consisted in determining the changes in shear stress as a function of shear time at constant average shear velocity of 50 mm/s. The results showed a significant influence of kinematic conditions on the value of friction. Four different cases of lubricant flow during friction were identified. The least resistance to motion was found when the lubricant was applied in the same direction along the surface of the roller and plate. It has been shown that the greatest influence of the kinematics of working elements on friction occurs at low temperatures, i.e. at -10°C. This phenomenon is closely related to the rheological properties of the lubricant. It was also found that the lubricant thickened with bentonite is the most susceptible to kinematic changes of the friction joint.
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Singh, Devendra, G. D. Thakre, L. N. Sivakumar Konathala i V. V. D. N. Prasad. "Friction Reduction Capabilities of Silicate Compounds Used in an Engine Lubricant on Worn Surfaces". Advances in Tribology 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/1901493.
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Effects of magnesium silicate and alumina dispersed in engine lubricant on friction, wear, and tribosurface characteristics are studied under boundary and mixed lubrication conditions. Magnesium silicate and alumina, henceforth called as friction reducing compounds (FRC), were dispersed in engine lubricant in very low concentration of 0.01% weight/volume. Four-ball wear test rig was used to assess friction coefficient and wear scar diameter of balls lubricated with and without FRC based engine lubricant. Scanning electron microscopy (SEM) equipped with Energy Dispersive X-ray (EDX) was used to analyse the tribosurface properties and elemental distributions on worn surfaces of the balls. Test results revealed that FRC based engine lubricant increases friction coefficient but marginally reduces wear scar diameter of new balls, whereas, test on the worn-out balls running on FRC based engine lubricants shows 46% reduction in friction coefficient compared to the new balls running on engine lubricants without FRC. Investigations on tribosurfaces with respect to morphology and elemental distribution showed the presence of Si and O elements in micropores of the worn surfaces of the balls, indicating role of FRC in friction coefficient reduction and antiwear properties. These FRC based engine lubricants may be used in the in-use engines.
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Lee, Sung-Jun, Yoon-Chul Sohn i Chang-Lae Kim. "Tribological Effects of Water-Based Graphene Lubricants on Graphene Coatings". Materials 16, nr 1 (26.12.2022): 197. http://dx.doi.org/10.3390/ma16010197.
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In this study, the friction and wear characteristics of graphene coatings were evaluated using lubricants with various ratios of graphene ink to deionized (DI) water. When dry graphene ink and pure DI water were used as lubricants, the graphene coating initially peeled off, and the friction coefficient rapidly increased to a large value. However, when a lubricant with graphene ink added to DI water was used, a lubricating film was formed on the graphene coating and the friction coefficient was reduced significantly. Under dry and pure DI water conditions, severe wear morphologies were formed on the graphene coating surface, whereas in the case of the lubricant with graphene inks added to DI water, insignificant wear morphologies were formed. When the mixing ratio between DI water and graphene ink was 100:10 and 100:5, the friction coefficient and wear rate were the lowest, respectively. As a result of a long-term experiment in which the sliding cycle was performed for up to 100,000 cycles under the same experimental conditions, the lubricant with a 100:10 mixing ratio showed excellent lubrication properties, confirming that the friction coefficient and wear rate were significantly reduced compared to that of the dry or pure DI water lubrication conditions.
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Kharchenko, M. V., V. N. Kononov i E. S. Zambrgitckaya. "Elastohydrodynamic Friction Mode as a Method of Surface Finishing Excluding Burnishing". Materials Science Forum 946 (luty 2019): 732–38. http://dx.doi.org/10.4028/www.scientific.net/msf.946.732.
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Over the past decades the science of friction has got great development. Processes of friction and wear significantly depend on constructive junction design, selection of wear resistant materials and effective lubricants for them, as well as the conditions of the machinery operation. Currently, a large number of scientific works [7-11, 16-20] are devoted to the review of the contact interaction conditions with the use a lubricant. The method of elastohydrodynamic lubrication is of particular interest when studying different kinds of lubrication. According to the elastohydrodynamic lubrication theory, contact conditions of two elastic bodies are characterized by high pressures which cause the elastic deformation of solids and by the dependence of a lubricant viscosity from the pressure. When using the elastohydrodynamic lubrication the layer profile, the sum amount of elastic deformations, elastic deformations and the lubricant viscosity dependence from pressure are given by set equations [12-15]. The impact of elastohydrodynamic lubrication method on the surface layer of the contacting parts is of great interest.
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Kang, Hae Suk, Jae Young Lee, Bo Kyong Kim i Tae Soon Kwon. "Application of the Electrokinetic-Fenton Process for the Treatment of Lubricant-Contaminated Railroad Soil". Advanced Materials Research 955-959 (czerwiec 2014): 2248–53. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.2248.
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Soil pollution around railroad sites is mainly caused by heavy oils such as diesel and lubricants. In particular, the majority of contamination in soil around railroad turnouts is caused by oil that drips off of railcars and lubricants that leak during vehicle maintenance. Generally, removing lubricants from contaminated soil is more difficult than removing diesel, due to the properties of the respective oils. This study aims to investigate alternative remediation method of lubricant-contaminated soils around railroad turnouts. The EK-Fenton process was used to clean up the lubricant-contaminated railroad soil. Several operating conditions were tested, including the concentration of hydrogen peroxide, and electrolyte types and concentrations. We determined that the removal efficiency was affected by the amount of EOF in the soil and its oxidizing capacity. The TPH removal efficiency was greatest at 0.1 M of NaCl electrolyte and 5 % (v/v) of hydrogen peroxide. This shows that the in-situ EK-Fenton process is a promising remediation technique for decontaminating railroad soil polluted with lubricant oil.
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Pan, Di, Guangqing Zhang, Fanghui Jia, Lianjie Li, Tao Zhang, Yao Lu, Hui Wu, Ming Yang i Zhengyi Jiang. "Analysis of TiO2 Nanolubricant Influence in Micro Deep Drawing of Stainless Steel SUS301". Materials 16, nr 6 (9.03.2023): 2196. http://dx.doi.org/10.3390/ma16062196.
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To improve the quality of products produced from microforming, various nanolubricants have been applied in the field of micromanufacturing in recent years. In this paper, the effects of glycerol-based lubricant containing TiO2 NPs (NPs) on micro deep drawing (MDD) of austenitic stainless steel (ASS) SUS301 were studied, and the lubrication mechanism involved was discussed. The MDD experiments were conducted with the SUS301 foils under dry, 1, 2, and 4 wt% TiO2 NP lubrication conditions. The results show that the use of the TiO2 nanolubricants can significantly improve the quality of the drawn cups in terms of decreased wrinkling and surface roughness. Besides, the concentration of TiO2 NPs influences lubricity by reducing friction during the MDD process. The peak drawing force is the lowest when 2 wt% nanolubricant is applied, which drops to 72.54 N from 77.38 N under dry conditions. The micro cup drawn under 2 wt% TiO2 nanolubricant has the best quality among those obtained under all the lubrication conditions. The lubrication mechanisms are derived from the mending effects of TiO2 NPs and the formation of thin lubricant films associated with the open lubricant pockets (OLPs) and close lubricant pocket (CLPs) theory in the MDD. The CLPs function as reservoirs that retain lubricants to counteract the load pressure, whereas the OLPs lead to lubricant leakage due to the higher flow resistance. It was found that the lubricant film and NPs are insufficient at a low concentration (1 wt%), while the lubrication performance can be enhanced with increased NP concentration. However, there exist apparent agglomerations on the surface of the produced micro cup when using 4 wt% nanolubricant, which greatly deteriorates the lubricant performance in the MDD process. It is concluded that the lubricant containing 2 wt% TiO2 NPs demonstrates the best lubrication performance during the MDD of ASS SUS301.
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Trzepieciński, Tomasz, Krzysztof Szwajka i Marek Szewczyk. "Pressure-Assisted Lubrication of DC01 Steel Sheets to Reduce Friction in Sheet-Metal-Forming Processes". Lubricants 11, nr 4 (8.04.2023): 169. http://dx.doi.org/10.3390/lubricants11040169.
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Friction in sheet-metal-forming processes not only affects the values of the force parameters of the process but also determines the quality of the surface of the drawpieces. This paper presents an approach to reducing the coefficient of friction by directly applying pressurized oil to the contact zone. For this purpose, a special test stand was built to carry out the strip draw test, commonly used to model the phenomenon of friction in the deep-drawing process. This test consisted of pulling a strip between flat countersamples made of 145Cr6 cold-work tool steel covered with an abrasion-resistant Mtec (AlTiN) coating. During the pilot tests, various contact pressures, lubricants with different viscosities, and different lubricant pressures were used. The influence of friction conditions on the surface roughness of the samples and the relationship between the friction conditions and the value of the coefficient of friction were determined. The supply of the lubricant under pressure into the contact zone has a beneficial effect on reducing friction. The coefficient of friction decreases with increasing lubricant pressure for contact pressures of 2–6 MPa. For a contact pressure of 8 MPa, the lubricant pressure is the least favorable for reducing the coefficient of friction. At higher lubricant pressures (12 and 18 bar), the lubrication efficiency depends on the viscosity of the lubricant and decreases with increasing contact pressure.
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Holweger, Walter, Luigi Bobbio, Zhuoqiong Mo, Joerg Fliege, Bernd Goerlach i Barbara Simon. "A Validated Computational Study of Lubricants under White Etching Crack Conditions Exposed to Electrical Fields". Lubricants 11, nr 2 (28.01.2023): 45. http://dx.doi.org/10.3390/lubricants11020045.
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The problem of White Etching Cracks (WEC) leading to failures in the life cycle of industrial and automotive drive trains has existed for more than 30 years. Many parameters leading to WEC, such as the presence of electricity, unfavorable lubricants, and other factors, have been identified by the use of test rigs. However, since (a) within lifecycle operation these impacts appear incidentally, and (b) the identified impacts stimulate each other as stated in WEC research, the appearance of WEC in a drive train is impossible to predict for any given application. This difficulty causes WEC to be a serious problem. Obtaining reliable failure prediction rates using construction guidelines is still impossible, resulting in warranty claims. The aim of this paper is, first, to establish a routine to determine if and how lubricants could be described numerically with respect to their susceptibility toward electrical fields and to see how this factor could be added in a later stage to construction guidelines. Second, this paper aims to give advice to the applicant in terms of countermeasures. Currently, as predictors are missing, extensive and time-consuming testing is required. Contradictory test results in the field of application, indicate the need for fundamental parameters to determine in which circumstances the application is exposed to WEC risk and to suggest countermeasures. The current study presents a simulation method based solely on the chemical structure of lubricant components, investigating the appearance of WEC and their response to increasing electrical fields. The results show a clear pattern in WEC criticality with respect to lubricants: if two or more components present in the lubricant create clusters through their dipolar interaction, an apparent WEC risk could be accurately predicted apart from test rig results. These clusters are charged like one big particle in an early stage of electrical field exposure. As a result, the surface area increases, facilitating a higher uptake of charge. The incidental breakdown of this charge is assumed. As the charge of a cluster is higher than that of single molecules, WEC critical lubricants are subjected to this pattern. The study validates these results by comparing them using lubricants known to be critical with respect to WEC, suggesting further tests in the near future. Despite the fact that some lubricants seem more critical than others related to WEC, each lubricant clearly might lead to WEC under given conditions. Thus, constructing guidelines for a prediction routine is essential.
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Tawakoli, Taghi, Abdolreza Rasifard i Alireza Vesali. "Effect of the Coolant Lubricant Type and Dress Parameters on CBN Grinding Wheels Performance". Advanced Materials Research 76-78 (czerwiec 2009): 163–68. http://dx.doi.org/10.4028/www.scientific.net/amr.76-78.163.
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The efficiency of using of CBN grinding wheels highly depends on the dressing process as well as on the coolant lubricant used. The Institute of Grinding and Precision Technology (KSF) investigated the performance of vitrified CBN grinding wheels -being dressed using different parameters- while using two different grinding oils and two different water-miscible coolant lubricants. The obtained results show that the performance of the vitrified CBN grinding wheels regarding the quality of the workpiece surface, the grinding forces as well as the wear of the grinding wheel, highly depend on the dressing conditions and the type of the coolant lubricant used. Compared to the water-miscible coolant lubricants, the grinding oils show better results.
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Östensen, J. O., H. Åström i E. Höglund. "Analysis of a Grease-Lubricated Roller Bearing under Arctic Conditions". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 209, nr 3 (wrzesień 1995): 213–20. http://dx.doi.org/10.1243/pime_proc_1995_209_427_02.
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This paper summarizes measurements of starting torque and motion of the rollers in a roller bearing during start-up at a temperature of − 30°C. The bearing was lubricated with three different greases and the tests were carried out after a running-in procedure at + 20 °C. The results were compared with measurements obtained at +20°C and with results from one base oil at +20°C. A model for the roller motion was also built and simulations of the roller motion were compared with the measurements. Independent of temperature and lubricant the rollers rolled in the loaded zone and slipped, more or less, in the unloaded zone. The degree of sliding in the unloaded zone was found to be governed mainly by the local lubricant distribution and the position of the roller in the cage pocket. Some differences are also seen in the slide-roll ratio between the lubricants. A roller diameter difference of 1.3 pm gave a significant difference in roller motion, with the slightly thinner roller slides more in the unloaded zone of the bearing.
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Taylor, R. I. "Engine friction: The influence of lubricant rheology". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 211, nr 3 (1.03.1997): 235–46. http://dx.doi.org/10.1177/135065019721100306.
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The sensitivity of engine friction to lubricant viscometry has been determined for a modern fuelefficient engine, the Mercedes Benz M111 2.0 litre gasoline engine, under both cold starting and fully warmed-up conditions. The study has taken into account realistic lubricant viscometric parameters such as the lubricant viscosity variation with shear rate and temperature. Results are reported for the variation of engine friction with different monograde and multigrade lubricants, including the distribution of friction losses between valve train, piston assembly and bearings with the different lubricant types. The work also enabled estimates to be made of the proportion of hydrodynamic and boundary friction in the engine, since the vast majority of boundary lubrication occurs in the valve train. Knowledge of the ratio of boundary to hydrodynamic lubrication was found to be important since the two key lubricant parameters that can be varied are (a) viscosity and (b) the introduction of a friction modifier additive. The viscosity of the lubricant will affect the hydrodynamically lubricated parts of the engine whereas the presence of a friction modifier will reduce boundary friction in the engine. Brief comparisons are made of the lubricant sensitivity of the Mercedes Benz M111 engine with other important fuel-efficient engines (such as the Ford Sequence VI and Ford Sequence VIA engines).
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Mohamad, Wan Farhana, Amir Azam Khan, Pierre Barroy, Olivier Durand-Drouhin, Clement Puille, Abdelilah Lahmar i Faiz Ahmad. "Sliding Friction Behavior of Sintered Ni-Cr Composites with Solid Lubricants". Key Engineering Materials 875 (luty 2021): 272–79. http://dx.doi.org/10.4028/www.scientific.net/kem.875.272.
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High temperature applications of self-lubricated sliding surfaces have gained industrial importance during the recent years. One popular system is based on sintered Ni-Cr composites with addition of solid lubricants. In the present work these composites were prepared under controlled sintering conditions with different combinations of solid lubricants (MoS2, Ag and CaF2) at 1200 °C under flowing argon. The physical properties such as sintered density, relative density and porosity were studied. The microstructures and phase studies of the Ni-Cr based composites were conducted using SEM analysis while the hardness of the composites was measured by Vickers Micro Hardness Tester. The friction tests were conducted with ball on disc configuration following ASTM G-99-95a standard. The MoS2 solid lubricant provides best lubrication at room temperature which is demonstrated by a low friction coefficient compared to pure Ni-Cr composites. The SEM pictures of worn out tracks show solid debris distribution, and filling of pores with solid lubricant phases. The time taken for stabilization of friction coefficient also varies with the type of solid lubricant. Dual and multiple additions of solid lubricants are also able to reduce the friction of coefficient compared to pure Ni-Cr composite.
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Koc¸, Muammer. "Tribological Issues in the Tube Hydroforming Process—Selection of a Lubricant for Robust Process Conditions for an Automotive Structural Frame Part". Journal of Manufacturing Science and Engineering 125, nr 3 (23.07.2003): 484–92. http://dx.doi.org/10.1115/1.1580526.
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In this paper, an overall review of tribological issues in the tube hydroforming process is presented. Guidelines for the selection of lubricants under the hydroforming process conditions are summarized following a description of existing testing methods and apparatus. A methodology of combined experiments and FEA was presented to determine the coefficient of friction in the hydroforming process in addition to selecting a proper lubricant for a given part and process design. Experimental results showed that thickness of the final part at critical regions, amount of axial feeding and axial force are strong indicators of lubricant performance whereas effect of lubrication on the part flatness, corner radius formation and box dimensions are found to be negligible.
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Buse, Henrik, Fabian Schueler i Erika Hodúlová. "Planar Contact Fretting Test Method Applied to Solid Lubricants". Lubricants 9, nr 6 (21.05.2021): 58. http://dx.doi.org/10.3390/lubricants9060058.
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A new method of material and lubricant testing is demonstrated with a planar contact fretting wear tribometer under typical fretting wear conditions. The usual abstraction of contact geometries with an easy-to-align point or line contacts is deliberately dispensed to do justice to the frequently flat contacts of machine elements (shaft-hub connection, bearing seats, etc.). For the study, a new method of targeted observation of the contact surfaces during the test is used, which allows a time-lapse animation of the fretting wear progress of solid lubricant mixtures. Thus, the formation of possible transfer film build-up and the type of wear mechanism occurring can be visualized. This technique represents, in conjunction with additional analytical methods such as microscopy and SEM/EDX, a powerful tool to provide a better insight into the mechanisms of solid lubricant action under fretting conditions. To demonstrate the potential of this approach, a time to damage study is performed on commercial and self-prepared pastes from solid lubricants and white oil, where calcium hydroxide is a commonly employed solid lubricant for the avoidance of fretting wear is compared to other materials.
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Salodimitris, C. P., i P. G. Nikolakopoulos. "Effect of lubricant shear thinning behaviour on major functioning parameters of a pad bearing operating in hydrodynamic lubrication region". IOP Conference Series: Materials Science and Engineering 1235, nr 1 (1.03.2022): 012059. http://dx.doi.org/10.1088/1757-899x/1235/1/012059.
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Abstract Type of lubricant used for fluid film bearings is one of the most important factors to consider. Bearing characteristics have to maintain steady throughout a wide range of conditions. However, viscosity, which is one of the primary lubricant properties, highly deviates depending on environmental and operational conditions. Macro-molecular micro-structure of lubricants is strongly correlated to temperature and shear rate, leading to a shear thinning behaviour. This work aims in studying a pad bearing lubricated by a shear thinning oil in hydrodynamic region. Hydrodynamic wedge was modelled for a small fixed pad bearing of 8.5 mm inner radius, 14.5 mm outer radius, 40° angle and 50 μm inlet – outlet film thickness difference. Variety of cases were studied for several runner rotational velocities and minimum film thickness. Lubricant was modelled as a carreau fluid. Load carrying capacity, power losses, friction coefficient, mass flow rate, temperature and viscosity were evaluated. From the aspect of load carrying capacity, this specific pad bearing is optimally operating for rotational velocities of up to 100 krpm. Above this threshold, viscosity highly downgrades due to increase in temperature and shear rate, causing a negative impact in load capacity. Shear thinning behaviour of lubricants is of high importance and should not be considered negligible.
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Peña-Parás, Laura, Patricio García-Pineda, Demófilo Maldonado-Cortés, Gerardo Tadeo Garza i Jaime Taha-Tijerina. "Temperature dependence of the extreme-pressure behavior of CuO and TiO2 nanoparticle additives in metal-forming polymeric lubricants". Industrial Lubrication and Tribology 69, nr 5 (4.09.2017): 730–37. http://dx.doi.org/10.1108/ilt-02-2016-0023.
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Purpose The purpose of this work is to investigate the effect of temperature on the extreme-pressure (EP) properties of CuO and TiO2 nanoparticle-filled polymeric lubricants for metal-forming processes. Design/methodology/approach This paper studies the effect of nanoparticle additives of CuO and TiO2 on the load-carrying capacity of a metal-forming polymer lubricant used for deep-drawing at varying temperatures. EP measurements are performed with a four-ball tribotester according to the ITeE-PIB Polish method for testing lubricants under scuffing conditions. Tests are run at 25, 40, 60 and 75°C to further decrease the lubricant film thickness and determine the effect on the load-carrying capacity and the tribological mechanisms of nanoparticles. The tribological mechanisms of nanoparticles is studied using energy dispersive spectrometry (EDS). Findings Results indicate that nanoparticle additives increase the load-carrying capacity of the polymeric lubricant at all concentrations up to 60°C attributed to a mending effect and a reduction in the area of contact of moving surfaces; at 75°C, the improvement is lowered due to nanoparticle re-agglomeration. The best results are found with TiO2 nanoparticles due to their smaller size compared to CuO. Practical implications Nanoparticles of CuO and TiO2 are potential EP additives for metal-forming lubricants, providing protection to working components and extending tool life. Originality/value These results show the effectiveness and the tribological mechanisms of nanoparticle additives under EP conditions and increasing temperatures found in metal-forming processes.
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Skakun, V. V., R. M. Dzhemalyadinov i A. I. Aliyev. "Influence of Environmentally Friendly Coolant-Lubricants on the Thermal Loading of the Cutting Process When Countersinking". Proceedings of Higher Educational Institutions. Маchine Building, nr 4 (733) (kwiecień 2021): 40–47. http://dx.doi.org/10.18698/0536-1044-2021-4-40-47.
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The paper considers the influence of environmentally friendly coolant-lubricants on the temperature parameters of the cutting process during hole countersinking. Structural steel 20, corrosion-resistant steel 12X18N10T and titanium alloy VT1-0 were selected as the processed materials. Mineral oils, as well as environmentally friendly vegetable oils and esters based on them were used as coolant-lubricants. The coolant-lubricants feed was carried out using an environmentally oriented dosing unit, which allowed the lubricant to be sprayed into the cutting zone in portions of an aerosol, which provided greater penetration and reduced the liquid consumption. The study of the temperature state of the cutting process was carried out using an artificial, chromel-copel thermocouple, the junction of which was placed in the immediate vicinity of the cutting zone. The data obtained when using vegetable oils as a coolant-lubricant in operations running under conditions of pronounced adhesive wear indicate their competitiveness not only with mineral oils, but also with traditionally used oil coolant-lubricants.
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Spikes, H. A. "The Behaviour of Lubricants in Contacts: Current Understanding and Future Possibilities". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 208, nr 1 (marzec 1994): 3–15. http://dx.doi.org/10.1243/pime_proc_1994_208_345_02.
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The main role of a lubricant is to form a protective, low shear strength film between rubbing surfaces and thereby reduce friction and surface damage. The science, or art, of both the lubricant and the mechanical designer is to develop combinations of lubricant and mechanical system best able to form such films. This task is not straightforward since modern technology is continually demanding lower friction and better protection over an ever-widening range of operating conditions. Furthermore, environmental concerns are also producing both design constraints and the need for rapid change. The aim of this paper is to show how progress is being made by experimental research which looks inside rubbing contacts to see how lubricants behave therein. The paper focuses on concentrated contacts, as found in gears, cams and rolling element bearings, and describes a number of techniques for probing such contacts to observe just how a range of lubricant types, from greases to emulsions, behave in such contacts to reduce friction and form films.
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Rempp, A., M. Widmann, A. Killinger i R. Gadow. "Advanced Ceramic / Metal Polymer Multilayered Coatings for Industrial Applications". Key Engineering Materials 533 (grudzień 2012): 133–44. http://dx.doi.org/10.4028/www.scientific.net/kem.533.133.
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For the reduction or complete compensation of grease and lubricants in mechanical engineering, special combined coatings for machine components with extended tribological and chemical properties have been developed. Ceramic or metal polymer coating systems are a combination of thermally sprayed hard materials with polymers containing solid lubricants of inorganic and fluorpolymeric origin (i.e. lubricant lacquers). The thermally sprayed hard material guarantees hardness and wear resistance and the lubricant lacquer causes low friction coefficients and smooth gliding performance. In this paper, results of different polymer and multicoating systems on steel substrates are presented. Molybdenum, a cermet based on tungsten carbide, a copper based alloy and chromia were used as wear resistant materials and deposited by means of High Velocity Flame Spraying (HVOF/HVLF). On these surfaces, lubricant lacquers of some μm thickness were deposited by air spraying. The life-time and the friction coefficient of the resulting layers depending on surface texture of the hard material or substrate and lacquer composition were determined using a twin disc tester under dry sliding conditions.
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Zahid, Rehan, Muhammad Usman Bhutta, Riaz Ahmad Mufti, Muhammad Usman Abdullah, Haji Hassan Masjuki, Mahendra Varman, Muhammad Abul Kalam, Mian Ashfaq Ali, Jawad Aslam i Khalid Akhtar. "Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines". Materials 14, nr 23 (26.11.2021): 7206. http://dx.doi.org/10.3390/ma14237206.
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The environmental concerns associated with artificially formulated engine oils have forced a shift towards bio-based lubricants. The deposition of hard coatings on engine components and migrating to environmentally friendly green lubricants can help in this regard. Chemically modified forms of vegetable oils, with better low-temperature characteristics and enhanced thermo-oxidative stability, are suitable substitutes to conventional lubricant base oils. The research presented in this manuscript was undertaken to experimentally investigate the wear and friction performance of a possible future generation of an environmentally friendly bio-based lubricant as a potential replacement for conventional engine lubricants. In order to quantify the tribological benefits which can be gained by the deposition of DLC coatings, (an (a-C:H) hydrogenated DLC coating and an (a-C:H:W) tungsten-doped DLC coating) were applied on the cam/tappet interface of a direct acting valve train assembly of an internal combustion engine. The tribological correlation between DLC-coated engine components, lubricant base oils and lubricant additives have been thoroughly investigated in this study using actual engine operating conditions. Two additive-free base oils (polyalphaolefines (PAO) and chemically-modified palm oil (TMP)) and two multi-additive-containing lubricants were used in this investigation. Real-time drive torque was measured to determine the friction force, detailed post-test analysis was performed, which involved the use of a specialized jig to measure camlobe wear. An optical profilometer was used to measure the wear on the tappet, high-resolution scanning electron microscopy was employed to study the wear mechanism and energy-dispersive X-ray spectroscopy was performed on the tested samples to qualitatively access the degradation of the coating. When using additive-free TMP, a low friction coefficient was observed for the cam/tappet interface. The presence of additives further improved the friction characteristics of TMP, resulting in reduced average friction torque values. A tremendous enhancement in wear performance was recorded with a-C:H-coated parts and the coating was able to withstand the test conditions with little or no delamination.
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Hou, Suo Xia, Hui Gao i Xiao Ming Jia. "Research of the New Composite Solid Lubricant Coating". Advanced Materials Research 652-654 (styczeń 2013): 1719–22. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.1719.
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MoS2、WS2、Sb2O3are common metal friction solid lubricants. Three substances can be complex preparation to create a new type of high temperature composite solid lubricant coating. We get the optimal ratio of such coatings through orthogonal experiment and explore the lubricating properties of the coating and find that the composite coating is good lubricity and wear resistance under high temperature conditions.
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Qian, Yong, Hongying Gong, Xiaoyun Zhao, Lei Cao, Weizhong Shi i Jianli He. "Experimental investigation on the tribological property of functionalized graphene lubricant against steel". Industrial Lubrication and Tribology 72, nr 3 (2.01.2020): 307–14. http://dx.doi.org/10.1108/ilt-08-2019-0344.
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Purpose The purpose of this study is to corroborate the advanced tribological properties of graphene as a lubricant additive. Design/methodology/approach Different concentrations of functionalized graphene were coated on the substrate surface. Tribological properties of the graphene lubricants were carried out by ball-on-disk tribology tests. Wear mechanism of functionalized graphene was studied by observing wear scars on the substrate surface. Finally, the wear resistance of modified graphene was calculated by calculating and analyzing the applied experimental conditions and the obtained experimental data. Findings The best concentration of graphene lubricant is 0.5 wt.% which shows the best tribological performance. And the coefficient of friction is 0.08. Compared with the dry friction condition, the coefficient of friction and wear rate of best graphene lubricant decreased by 80% and 82%. Originality/value The formula of graphene lubricant is independently developed and works very well. Graphene lubricant can prevent the substrate from oxidation. The thickness of the graphene lubricant is about 4-7µm. The concept of anti-wear strength was introduced in this paper. When 0.5 Vol.% graphene was added, the anti-wear strength was greatly improved from 115.3 kg·mm-2 to 657.6 kg·mm-2. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0344
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Costa, Henara Lillian, Tiago Cousseau i Roberto Martins Souza. "Current Knowledge on Friction, Lubrication, and Wear of Ethanol-Fuelled Engines—A Review". Lubricants 11, nr 7 (12.07.2023): 292. http://dx.doi.org/10.3390/lubricants11070292.
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The urgent need for drastic reduction in emissions due to global warming demands a radical energy transition in transportation. The role of biofuels is fundamental to bridging the current situation towards a clean and sustainable future. In passenger cars, the use of ethanol fuel reduces gas emissions (CO2 and other harmful gases), but can bring tribological challenges to the engine. This review addresses the current state-of-the-art on the effects of ethanol fuel on friction, lubrication, and wear in car engines, and identifies knowledge gaps and trends in lubricants for ethanol-fuelled engines. This review shows that ethanol affects friction and wear in many ways, for example, by reducing lubricant viscosity, which on the one hand can reduce shear losses under full film lubrication, but on the other can increase asperity contact under mixed lubrication. Therefore, ethanol can either reduce or increase engine friction depending on the driving conditions, engine temperature, amount of diluted ethanol in the lubricant, lubricant type, etc. Ethanol increases corrosion and affects tribocorrosion, with significant effects on engine wear. Moreover, ethanol strongly interacts with the lubricant’s additives, affecting friction and wear under boundary lubrication conditions. Regarding the anti-wear additive ZDDP, ethanol leads to thinner tribofilms with modified chemical structure, in particular shorter phosphates and increased amount of iron sulphides and oxides, thereby reducing their anti-wear protection. Tribofilms formed from Mo-DTC friction modifier are affected as well, compromising the formation of low-friction MoS2 tribofilms; however, ethanol is beneficial for the tribological behaviour of organic friction modifiers. Although the oil industry has implemented small changes in oil formulation to ensure the proper operation of ethanol-fuelled engines, there is a lack of research aiming to optimize lubricant formulation to maximize ethanol-fuelled engine performance. The findings of this review should shed light towards improved oil formulation as well as on the selection of materials and surface engineering techniques to mitigate the most pressing problems.
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GÓRNY, Kasper, Arkadiusz STACHOWIAK, Przemysław TYCZEWSKI i Wiesław ZWIERZYCKI. "LUBRICITY OF OIL-REFRIGERANT MI XTURES WITH R600A UNDER STARVED LUBRICATION CONDITIONS". Tribologia 279, nr 3 (1.07.2018): 43–50. http://dx.doi.org/10.5604/01.3001.0012.7010.
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In refrigeration nowadays, there is a dynamic return to the use of natural refrigerants such as hydrocarbons. These substances do not contain fluorine and chlorine, which contribute to the enlargement of the ozone hole and the greenhouse effect. Hydrocarbons, however, are substances from the A3 safety group (flammable) and are currently mainly used in low-capacity devices. The most commonly used refrigerant in this group is R600a (isobutene). In refrigeration compressors, a situation may occur where the amount of oil in friction nodes is insufficient. In this case, there may be poor lubrication conditions. A situation may also arise in which the lubricant in the friction areas runs out, and the lubrication of the friction nodes will be performed exclusively by the refrigerant. The article presents a concept of a test method allowing an assessment of lubricity properties of oils for refrigeration compressors in the mixture with a refrigerant in the conditions of poor lubrication and in the absence of lubrication with a lubricant. It also contains the results of wear tests that enable an evaluation of the lubricity properties of oil-refrigerant mixtures in the conditions of poor lubrication. The results were obtained for ecological, and recommended for a wider future use, R600a refrigerant with mineral oils. It is also indicated that it is possible to compare various refrigerants in the absence of lubricant and to replicate lubricity properties of oil-refrigerant mixtures in the conditions of poor lubrication and to apply the proposed method for the evaluation of different lubricants in use with a selected refrigerant.