Effect of Friction Velocity on Tribological Behavior of Coumarin as Mineral Oil Additive

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Huajie Tang ◽  
Jianlin Sun ◽  
Zhangliang Zhao ◽  
Zhao Han
Keyword(s):  
Friction Velocity ◽  
Tribological Behavior ◽  
Hydrodynamic Lubrication ◽  
Lauryl Alcohol ◽  
Ester Group ◽  
Wear Scar Diameter ◽  
Obvious Effect ◽  
Base Oil ◽  
Mineral Oils ◽  
Variable Friction

Abstract The tribological behavior of lubricants, prepared with a mineral base oil, lauryl alcohol, and different concentrations of coumarin, was examined using a four-ball tester under constant and variable friction velocity conditions. At constant friction velocity, the maximum non-seizure load (PB) increased from 304 N to 392 N at a coumarin concentration of 0.5 wt%. Lubricants with 0.7 wt% coumarin exhibited optimum lubricating properties, and the maximum reductions in friction coefficient (FC) and wear scar diameter (WSD) were 20.0% and 11.88%, respectively. Further investigation of the tribological mechanism implied that the ester group in the coumarin molecule established a connection with the surface atom, resulting in the formation of a tribofilm, which further restricted the adhesion wear regime. Additionally, under variable friction velocity conditions, increasing the coumarin concentration had an obvious effect on the mixed lubrication (ML) and elasto-hydrodynamic lubrication (EHL) regions but not on other lubrication regions. Moreover, a mathematical model was proposed to show the relationship between FC and friction velocity. Importantly, the present work clarifies the effect of friction velocity on the tribological behavior of coumarin and also supports the use of coumarin as a novel additive in mineral oils.

scholarly journals Optimization of the Rheological Properties and Tribological Performance of SAE 5w-30 Base Oil with Added MWCNTs

Lubricants ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 94
Author(s):  
Bahaa M. Kamel ◽  
Vineet Tirth ◽  
Ali Algahtani ◽  
Mohamed S. Shiba ◽  
Ahmed Mobasher ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Rheological Properties ◽  
Kinematic Viscosity ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Wear Scar Diameter ◽  
Multiwalled Carbon ◽  
Base Oil ◽  
Weight Percentage ◽  
Lubricant Oil

The augmentation of lubricant oil properties is key to protecting engines, bearings, and machine parts from damage due to friction and wear and minimizing energy lost in countering friction. The tribological and rheological properties of the lubricants are of utmost importance to prevent wear under unembellished conditions. The marginal addition of particulate and filamentous nanofillers enhances these properties, making the lubricant oil stable under severe operating conditions. This research explores the improvement in SAE 5w-30 base oil performance after the addition of multiwalled carbon nanotubes (MWCNTs) in six marginal compositions, namely, Base, 0.02, 0.04, 0.06, 0.08, and 0.10 weight percentage. The effect of the addition of MWCNTs on flash and pour points, thermal conductivity, kinematic viscosity, friction coefficients, and wear are investigated and reported. X-ray diffraction and transmission electron microscopy are used to characterize the MWCNTs. The purity, crystallinity, size, shape, and orientation of the MWCNTs are confirmed by XRD and TEM characterization. Pour points and flash points increase by adding MWCNTs but inconsistency is observed after the 0.06 wt.% composition. The thermal conductivity and kinematic viscosity increase significantly and consistently. The friction coefficient and wear scar diameter reduce to 0.06 wt.% MWCNTs and then the trend is reversed due to agglomeration and inhomogeneity. A composition of 0.06 wt.% is identified as the optimum considering all the investigated properties. This composition ensures the stability of the tribo-film and hydrodynamic lubrication.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

scholarly journals Tribological Performance Investigation of a Commercial Engine Oil Incorporating Reduced Graphene Oxide as Additive

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 386
Author(s):  
Hakan Kaleli ◽  
Selman Demirtaş ◽  
Veli Uysal ◽  
Ioannis Karnis ◽  
Minas M. Stylianakis ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Tribological Behavior ◽  
Control Sample ◽  
Protective Layer ◽  
Steel Ball ◽  
Carbon Accumulation ◽  
Engine Oil ◽  
Wear Scar Diameter ◽  
Reduced Graphene

We investigated the tribological behavior of commercialized, fully synthetic engine oil upon the incorporation of reduced graphene oxide in seven different concentrations between 0.01 and 0.2 wt %. Stability of the prepared samples was assessed by turbidimetry and dynamic light scattering measurements, and their tribological properties through a reciprocating tribometer, using a steel ball on special cut steel blocks. The addition of 0.02 wt % of reduced graphene oxide led to an improvement of the tribological behavior compared to the pristine engine oil, by significantly lowering the friction coefficient by 5% in the boundary lubrication regime. Both the surfaces and the reduced graphene oxide additive were thoroughly characterized by microscopic and optical spectroscopy techniques. We also verified that a protective layer was formed between the worn surfaces, due to the presence of reduced graphene oxide. Carbon accumulation and various additive elements such as Ca, Zn, S and P were detected on the rubbing surfaces of both the ball and the block through energy-dispersive X-ray spectroscopy. Finally, it was shown that the wear scar diameter on the surface of the steel ball was lower by 3%, upon testing the engine oil sample containing reduced graphene oxide at concentration 0.02 wt %, compared to the control sample.

Experimental Research on Tribological Properties of Mn0.78Zn0.22Fe2O4 Magnetic Fluids

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Wang Li-jun ◽  
Guo Chu-wen ◽  
Ryuichiro Yamane
Keyword(s):  
Tribological Properties ◽  
Friction And Wear ◽  
Chemical Properties ◽  
Friction Reduction ◽  
Experimental Investigations ◽  
Wear Scar Diameter ◽  
Base Oil ◽  
Turbine Oil ◽  
Physical And Chemical ◽  
And Chemical Properties

The synthesis and application of nanometer-sized particles have received considerable attention in recent years because of their different physical and chemical properties from those of the bulk materials or individual molecules; however, few experimental investigations on the tribological properties of lubricating oils with and without nanoferromagnetic particles have been performed. This work investigates the tribological properties of Mn0.78Zn0.22Fe2O4 nanoferromagnetic as additive in 46# turbine oil using a four-ball friction and wear tester. It is shown that the 46# turbine oil containing Mn0.78Zn0.22Fe2O4 nanoparticles has much better friction reduction and antiwear abilities than the base oil. The 46# turbine oil doped with 6wt%Mn0.78Zn0.22Fe2O4 nanoparticles show the best tribological properties among the tested oil samples, and PB value is increased by 26%, and the decreasing percentage of wear scar diameter is 25.45% compared to base oil.

Static thermal performance evaluation of elliptical journal bearings with nanolubricants

2020 ◽  
pp. 135065012097074
Author(s):  
Rajeev Kumar Dang ◽  
Amit Chauhan ◽  
SS Dhami
Keyword(s):  
Thermal Performance ◽  
Load Capacity ◽  
Journal Bearings ◽  
Maximum Pressure ◽  
Stable Operation ◽  
Base Oil ◽  
Lubrication Film ◽  
Mineral Oils ◽  
Appreciable Increase ◽  
Thermo Physical Properties

Journal bearings of different configurations have been extensively used in turbomachinery and power generating equipments. Although circular bearings have simplest configuration and commonly used journal bearings, non-circular bearings such as multi-lobe and elliptical bearings have an added advantage of lower lubrication film temperature alongwith stable operation. In this study, static thermal performance of pure elliptical bearing lubricated with nanoparticles based mineral oils has been studied at different eccentricity ratios and bearing speeds. Two types of nanoparticles, namely, CuO and TiO2 with 0.5, 1.0 and 2.0 wt.% concentrations have been separately added in three different viscosity grades of oils. The effect of nanoparticles on thermo-physical properties of oil was considered to compute bearing performance parameters (pressure distribution, load capacity, oil temperature and power losses). Bearing model was generated by taking into account the modified Krieger Dougherty method to determine viscosity at different combinations of oils and nanoparticles. The findings indicate the increase in maximum pressure and load capacity with addition of nanoparticles and this increase was more pronounced at higher concentrations of nanoparticles and at higher viscosity grade oils. Load capacity was found to be increased by 14.24% and 9.21% with 2 wt% concentration of TiO2 and CuO nanoparticles respectively in base oil (AW68) at eccentricity ratio of 0.7. An increase in load capacity with nanolubricants was achieved without an appreciable increase in oil temperature.

scholarly journals Tribological properties of novel palygorskite nanoplatelets used as oil-based lubricant additives

Friction ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 332-343 ◽  
Author(s):  
Kunpeng Wang ◽  
Huaichao Wu ◽  
Hongdong Wang ◽  
Yuhong Liu ◽  
Lv Yang ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Magnesium Silicate ◽  
Treatment Method ◽  
Lubricant Additives ◽  
Wear Volume ◽  
Wear Scar Diameter ◽  
Tribochemical Reaction ◽  
Base Oil ◽  
Transmission Electron ◽  
Ball Surface

AbstractLayered palygorskite (PAL), commonly called attapulgite, is a natural inorganic clay mineral composed of magnesium silicate. In this study, an aqueous miscible organic solvent treatment method is adopted to prepare molybdenum-dotted palygorskite (Amo-PMo) nanoplatelets, which greatly improved the specific surface area of PAL and the dispersion effect in an oil-based lubricant system. Their layered structure and size were confirmed using transmission electron microscopy (TEM) and atomic force microscopy. Following a tribological test lubricated with three additives (PAL, organic molybdenum (SN-Mo), and Amo-PMo), it was found that the sample of 0.5 wt% Amo-PMo exhibited the best tribological properties with a coefficient of friction of 0.09. Moreover, the resulting wear scar diameter and wear volume of the sliding ball surface were 63% and 49.6% of those lubricated with base oil, respectively. Its excellent lubricating performance and self-repairing ability were mainly attributed to the generated MoS2 adsorbed on the contact surfaces during the tribochemical reaction, thereby effectively preventing the direct collision between asperities on sliding solid surfaces. Thus, as-prepared Amo-PMo nanoplatelets show great potential as oil-based lubricant additives, and this study enriches the existing application of PAL in industry.

Performance of Surface Texturing During Start-Up Under Starved and Mixed Lubrication

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Chunxing Gu ◽  
Xianghui Meng ◽  
Youbai Xie ◽  
Xiaoli Kong
Keyword(s):  
Tribological Behavior ◽  
Hydrodynamic Lubrication ◽  
Surface Texturing ◽  
Mixed Lubrication ◽  
Textured Surface ◽  
Friction Heat ◽  
Start Up ◽  
Hot Start ◽  
Liner System ◽  
Lubricated Contact

In this paper, the start-up process of the ring/liner system with surface texturing is studied. By employing a thermal-mixed lubrication model considering the oil supply, the tribological behavior of the textured surface under the cold and hot start-up conditions is investigated. It is found that the friction coefficient curve under the cold start-up condition is different from the hot start-up result. The textured surface is easier to form the hydrodynamic lubrication than the smooth surface, which is helpful to separate the mixed lubricated contact surfaces. With the textured features on the ring face, the less friction heat is generated at the start-up phase. These effects could prove beneficial in applications with the frequent start and stop conditions. Besides, the inlet wedge of ring can also influence the start-up performance.

High Temperature Tribological Behavior of Nano-Al2O3 in Different Base Oils

2008 ◽  
Vol 373-374 ◽  
pp. 568-571 ◽  
Author(s):  
X.F. Sun ◽  
Yu Lin Qiao ◽  
Jia Wu He ◽  
Shi Ning Ma ◽  
C.H. Hu
Keyword(s):  
High Temperature ◽  
Ball Bearing ◽  
Tribological Behavior ◽  
Test System ◽  
High Load ◽  
Friction Coefficients ◽  
Base Oil ◽  
Base Oils ◽  
Al2o3 Particles ◽  
Reducing Properties

High temperature tribological behavior of nano-Al2O3 in different base oils were tested by a SRV multifunctional test system. The results show that the nano-Al2O3 particles can obviously improve the antiwear and friction reducing properties of the base oil under high temperature and high load. The friction coefficients of the base oil with added nano-Al2O3 are reduced about 35%, and abrasion loss reduces about 60%. When temperature is 500°C and load is 500N the pure base oil has lost lubricative function, but the base oil with added nano-Al2O3 can still remain the lower friction coefficients. Tribological behavior should be similar to the “ball bearing” lubrication action of the nano-Al2O3 particles, so the movement between the two tribological pairs becomes sliding/rolling.

Tribological behavior of polyacetal composite filled with rice bran ceramics particles under water lubrication

2017 ◽  
Vol 52 (15) ◽  
pp. 2075-2084 ◽  
Author(s):  
Kei Shibata ◽  
Takeshi Ii ◽  
Takeshi Yamaguchi ◽  
Kazuo Hokkirigawa
Keyword(s):  
Contact Pressure ◽  
Rice Bran ◽  
Tribological Behavior ◽  
Hydrodynamic Lubrication ◽  
Characteristic Number ◽  
Steel Ball ◽  
Water Lubrication ◽  
Roughness Parameters ◽  
Low Friction ◽  
Bearing Characteristic

We investigated the tribological behavior of polyacetal polyoxymethylenecomposite filled with rice bran ceramics particles under water lubrication, compared to those of polyoxymethylene composites filled with glass beads and glass fibers. Furthermore, the local contact pressure between a particle and the paired ball was calculated based on a simple contact model. The polyoxymethylene/rice bran ceramics composite showed low wear ( ws < 10−8 mm2/N) and low friction ( μ < 0.10) under water lubrication, irrespective of the normal load and sliding velocity. On a Stribeck curve, the lubrication condition of the polyoxymethylene/rice bran ceramics composite appeared to be near hydrodynamic lubrication. The specific wear rates of the polyoxymethylene/rice bran ceramics composite were the lowest of the composites, regardless of the bearing characteristic number. A smooth worn surface was observed for both the polyoxymethylene/rice bran ceramics composite and the paired ball. The dimensionless roughness parameters of the polyoxymethylene/rice bran ceramics composite were smaller than 1.0, irrespective of the bearing characteristic number. The friction coefficients of the polyoxymethylene composites decreased exponentially with decreasing dimensionless roughness parameter; the low friction of the polyoxymethylene/rice bran ceramics composite resulted from the small roughness parameters. The rice bran ceramics particles indicated a small contact pressure per particle, which was nearly half the Vickers hardness of the steel ball. As a result, the rice bran ceramics particles rarely damaged the steel ball with increasing surface roughness. Therefore, the low friction of the polyoxymethylene composite filled with the rice bran ceramics particles was attributable to the decrease in the roughness, e.g., polishing without the formation of a transfer film and the filler detachment.

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