scholarly journals Dependences of changes in the structural viscosity of oil films on the friction surface with fullerene compositions

2021 ◽  
Vol 100 (2) ◽  
pp. 34-40
Author(s):  
A. Kravtsov
Keyword(s):  
Tribological Properties ◽  
Friction Surface ◽  
Molecular Level ◽  
Physical Phenomenon ◽  
Structural Viscosity ◽  
Gel Structure ◽  
Additive Package ◽  
Base Oil ◽  
The Coefficient Of Friction ◽  
Oil Films

In this work, the physical phenomenon of the formation of an oil film containing fullerenes was further developed, on the friction surface of tribosystems, which, in contrast to the known ones, takes into account the structural viscosity and structure of the formed film under the action of the electrostatic field of the friction surface. An increase in load significantly increases the structural viscosity of the gel structure, 13 - 20 times. The concentration of fullerenes in the base lubricant does not significantly affect the dynamic viscosity of aggregates in the composition of the liquid and the structure of the gel. An increase in the tribological properties of the base lubricant medium reduces the value of the structural viscosity of the gel on the friction surface by a factor of 3. At the same time, the concentration of fullerenes in the range of 0.5 - 1.5% does not have a large effect on these indicators. This phenomenon can be explained by the presence or absence of an additive package in the base lubricating medium. For those oils where the additive package is absent or present in a small amount J/m3, the introduction of a fullerene composition promotes the formation of clusters and micelles, which increase the structural viscosity and, consequently, form a film on the friction surface in the form of a gel structure. Conversely, if fullerenes are introduced into a base oil that contains a large and balanced additive package, where tribological properties are high J/m3, interaction at the molecular level does not occur. Fullerenes to a lesser extent will form stable aggregates in the form of micelles. The effect of reducing the coefficient of friction, equal to 96 %, is typical for low and medium loads of operation of tribosystems and base lubricants with average values of tribological properties. With increasing loads or tribological properties of base oils, the effect of the use of fullerenes decreases.

scholarly journals Investigation of the structural viscosity of oil films on the friction surface with fullerene compositions

2021 ◽  
Vol 99 (1) ◽  
pp. 13-19
Author(s):  
A. Kravtsov ◽  
Keyword(s):  
Dynamic Viscosity ◽  
Friction Surface ◽  
Theoretical Studies ◽  
Structural Viscosity ◽  
Electrostatic Forces ◽  
Gel Structure ◽  
Structural Dynamic ◽  
Oil Film ◽  
The Coefficient Of Friction ◽  
Oil Films

The paper presents theoretical studies of changes in the structural viscosity of oil films on the friction surface with fullerene compositions in the field of action of electrostatic forces of the friction surface and the base lubricant. A feature of the use of fullerene additives in lubricants is that fullerenes are readily soluble in a wide class of organic and inorganic solvents. At the same time, poor solubility of fullerenes in technical oils (mineral, semi-synthetic and synthetic). The purpose of this work is to carry out theoretical studies of changes in the structural viscosity of oil films on the friction surface with fullerene compositions in the field of action of electrostatic forces of the friction surface and the base lubricant. On the basis of the working hypothesis, it was theoretically established that for a thin oil film, located in the field of action of electrostatic forces of the friction surface, it is necessary to consider the structural dynamic viscosity of the lubricant, which at the friction surface has a gel structure, and as the electrostatic forces from the friction surface decrease, the gel structure transforms into the sol structure. It is shown that the value of the structural viscosity of the considered aggregates is comparable with the viscosity of polymers or bitumen. Moreover, the viscosity of the gel structure is four orders of magnitude higher than the viscosity of the sol structure. An increase in the concentration of fullerenes leads to an increase in the dynamic viscosity of aggregates. It is theoretically shown that the structure of the oil film, which corresponds to the structure of the gel, belongs to the class of non-Newtonian fluids. With an increase in the sliding speed, the dynamic viscosity of such structures decreases by a factor of 4, which explains the destruction of micelle clusters and the appearance of rotational motions of elastic flocks. It is assumed that this will lead to a decrease in the value of the coefficient of friction. It is shown that for the gel structure, the concentration of fullerenes in the bulk of the base lubricant does not have a large effect on the structural viscosity. Conversely, for the structure of a sol, the concentration of fullerenes has a significant effect on the value of the structural dynamic viscosity.

Experimental Analysis of Tribological Properties of Simarouba Glauca Biodiesel With Nanoparticles

2021 ◽  
pp. 1388-1402
Author(s):  
Eknath Nivrutti Aitavade ◽  
S. C. Kamate
Keyword(s):  
Silicon Dioxide ◽  
Tribological Properties ◽  
Sio2 Nanoparticles ◽  
Cuo Nanoparticles ◽  
Base Oil ◽  
Wear And Friction ◽  
The Coefficient Of Friction ◽  
Simarouba Glauca ◽  
Friction Parameters ◽  
Friction And Wear Characteristics

Biolubricants are renewable, biodegradable, nontoxic, and have zero greenhouse gases. In this work, the tribological properties of the Simarouba glauca biodiesel (SBD) are studied with nanoparticles as additives. Nanoparticles of copper oxide (CuO) and silicon dioxide (SiO2) were added with 0.2, 0.5, 0.75, and 1% weight (wt) in the base SBD. The coefficient of friction (COF) and the wear scar diameters (WSD) were evaluated using four ball tester for the test conditions as per ASTM D 4172 standard. The morphologies of the worn surfaces were inspected by scanning electron microscope (SEM). The addition of nanoparticles improved the friction and wear characteristics of SBD. A combination of abrasive and adhesive wear was evident. The average COF for pure SBD was 0.0168. The results indicated that 0.75% and 0.2% of CuO nanoparticles as a beneficial percentage in the base oil exhibiting the lowest COF and WSD. CuO nanoparticles proved to be superior to SiO2 nanoparticles as additives in SBD, demonstrating 8% and 60% decrease in wear and friction parameters, respectively.

Comparative Study on Tribological Properties of Nanofluids in Friction-Wear Experiments and Grinding Processing

2020 ◽  
pp. 298-316
Keyword(s):  
Tribological Properties ◽  
Friction Surface ◽  
Film Formation ◽  
Interface State ◽  
Wear Properties ◽  
Element Analysis ◽  
Base Oil ◽  
Oil Film ◽  
Worn Surface ◽  
Lubricating Properties

This chapter presents the lubricating properties of different vegetable-oil-based nanofluids through a comparative evaluation between frictional test and grinding experiment. The first experiment aimed to prejudge the lubricating properties of different nanofluids with a frictional test, which simulated the interface state of grinding between the abrasive grains and the workpiece. The second aimed to test and verify the lubricating properties of the same nanofluids through a grinding experiment. The mechanism of oil-film formation of nanofluids in the grinding zone was analyzed by morphology and element analysis of the worn surface. The experimental results show that Al2O3 nanofluids have the best tribological properties. Compared with pure base oil, the friction coefficient is reduced by 20%, and the optimal friction surface morphology is obtained. The good anti-friction and anti-wear properties of nanofluids are attributed to the formation of the protective oil film formed by chemical reaction on the surface.

Experimental Analysis of Tribological Properties of Simarouba Glauca Biodiesel With Nanoparticles

2020 ◽  
Vol 8 (2) ◽  
pp. 52-65
Author(s):  
Eknath Nivrutti Aitavade ◽  
S. C. Kamate
Keyword(s):  
Tribological Properties ◽  
Friction And Wear ◽  
Sio2 Nanoparticles ◽  
Cuo Nanoparticles ◽  
Base Oil ◽  
Wear And Friction ◽  
The Coefficient Of Friction ◽  
Simarouba Glauca ◽  
Friction Parameters ◽  
Friction And Wear Characteristics

Biolubricants are renewable, biodegradable, nontoxic, and have zero greenhouse gases. In this work, the tribological properties of the Simarouba glauca biodiesel (SBD) are studied with nanoparticles as additives. Nanoparticles of copper oxide (CuO) and silicon dioxide (SiO2) were added with 0.2, 0.5, 0.75, and 1% weight (wt) in the base SBD. The coefficient of friction (COF) and the wear scar diameters (WSD) were evaluated using four ball tester for the test conditions as per ASTM D 4172 standard. The morphologies of the worn surfaces were inspected by scanning electron microscope (SEM). The addition of nanoparticles improved the friction and wear characteristics of SBD. A combination of abrasive and adhesive wear was evident. The average COF for pure SBD was 0.0168. The results indicated that 0.75% and 0.2% of CuO nanoparticles as a beneficial percentage in the base oil exhibiting the lowest COF and WSD. CuO nanoparticles proved to be superior to SiO2 nanoparticles as additives in SBD, demonstrating 8% and 60% decrease in wear and friction parameters, respectively.

scholarly journals Impact of Operating Time on Selected Tribological Properties of the Friction Material in the Brake Pads of Passenger Cars

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 884
Author(s):  
Andrzej Borawski
Keyword(s):  
Tribological Properties ◽  
Operating Time ◽  
Friction Material ◽  
Operating Conditions ◽  
Direct Impact ◽  
Passenger Cars ◽  
Wear Factor ◽  
Brake Pads ◽  
Road Users ◽  
The Coefficient Of Friction

Braking systems have a direct impact on the safety of road users. That is why it is crucial that the performance of brakes be dependable and faultless. Unfortunately, the operating conditions of brakes during their operating time are affected by many variables, which results in changes in their tribological properties. This article presents an attempt to develop a methodology for studying how the operating time affects the value of the coefficient of friction and the abrasive wear factor. The Taguchi method of process optimization was used to plan the experiment, which was based on tests using the ball-cratering method. The results clearly show that the degree of wear affects the properties of the friction material used in the production process of brakes.

scholarly journals Analysis and Comparative Assessment of Basic Tribological Properties of Selected Polymer Composites

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 75 ◽  
Author(s):  
Jerzy Jozwik ◽  
Krzysztof Dziedzic ◽  
Marcin Barszcz ◽  
Mykhaylo Pashechko
Keyword(s):  
Polymer Composites ◽  
Friction Force ◽  
Tribological Properties ◽  
Friction Pair ◽  
Computer Software ◽  
Operating Conditions ◽  
The Coefficient Of Friction ◽  
Cast Polyamide ◽  
Friction Path ◽  
Materials Used

Phenomena occurring in the contact area between two mating bodies are characterised by high complexity and variability. Comparisons are usually made between parameters such as the coefficient of friction, friction force, wear and temperature in relation to time and friction path. Their correct measurement enables the proper evaluation of tribological properties of materials used in the friction pair. This paper concerns the measurements of basic tribological parameters in the friction of selected polymer composites. Knowing the tribological properties of these composite materials, it will be possible to create proper operating conditions for kinematic friction pairs. This study investigated the coefficients of friction, friction force and temperatures of six polymer composites: cast polyamide PA6 G with oil, PA6 G with MoS2, polyoxymethylene POM with aluminium, polyethylene terephthalate PET with polytetrafluoroethylene PTFE, PTFE with bronze, and PTFE with graphite. The friction surface was also examined using an optical system and computer software for 3D measurements. As a result, PA6-G with oil was found to be the best choice as a composite material for thin sliding coatings.

scholarly journals Preparation of TiO2/Ti3C2Tx hybrid nanocomposites and their tribological properties as base oil lubricant additives

RSC Advances ◽  
2017 ◽  
Vol 7 (8) ◽  
pp. 4312-4319 ◽  
Author(s):  
Maoquan Xue ◽  
Zhiping Wang ◽  
Feng Yuan ◽  
Xianghua Zhang ◽  
Wei Wei ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Tribological Properties ◽  
Lubricant Additives ◽  
Hybrid Nanocomposites ◽  
Phase Synthesis ◽  
Base Oil

TiO2/Ti3C2Tx hybrid nanocomposites were successfully prepared by a liquid phase synthesis technology. The hybrid nanocomposites improve the tribological properties of base oil by mending the surface and formation a uniform tribofilm on the surface.

Tribological Properties of Zirconium Oxide, Spinel and Mullite Nanopowders as Lubricating Oil Additives

2016 ◽  
Vol 721 ◽  
pp. 451-455
Author(s):  
Armands Leitans ◽  
Eriks Palcevskis
Keyword(s):  
Tribological Properties ◽  
Zirconium Oxide ◽  
Friction Pair ◽  
Synthesis Method ◽  
Lubricating Oil ◽  
Nanosized Powders ◽  
Base Oil ◽  
Oil Additives ◽  
Oxide Spinel ◽  
Lubricating Oil Additives

In work investigated effects of zirconium oxide (ZrO2), spinel (MgAl2O4) and mullite (Al6Si2O13) nanosized powders on the base oil tribological properties. The nanosized (30-40nm) powders manufactured by plasma chemical synthesis method. Tribological experiments used on ball-on-disc type tribometer, measured coefficient of friction and determined metalic disc wear. Base oil used selectively purified mineral oil (conform SAE-20 viscosity) without any functional additives. Nanosized powders dispersed in base oil at 0.5; 1.0; 2.0; wt.%. At work cocluded, that the adition nanoparticles in base oil, possible reduced friction pair wear and friction coefficient. As the main results include spinel (MgAl2O4) nanoparticles 0.5 and 1.0 wt. % concentration ability reduced friction coeffiecient value.

Microstructure and Tribological Properties of Cu-Fe Based Braking Materials

2014 ◽  
Vol 941-944 ◽  
pp. 280-283
Author(s):  
Xiao Yang Wang ◽  
Hong Qiang Ru
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tribological Properties ◽  
X Ray Diffraction ◽  
Pressing Method ◽  
X Ray ◽  
The Coefficient Of Friction ◽  
Worn Surface ◽  
Scanning Electron ◽  
Sic Particle

SiC particle-reinforced Cu-Fe based braking materials were fabricated by the P/M hot pressing method. The phase composition, microstructure and the worn surface of the composite were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD).The tribological properties were evaluated using a disk-on-disk type laboratory scale dynamometer. Results indicate that the friction coefficient is 0.42 in 6800rpm, 0.7MPa. With the increase of rotation speeds the coefficient of friction and stable rate were decreased.

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