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.

Modifying Operating Conditions of the Friction Pair with an Additive Added to the Lubricant while Operating

2015 ◽  
Vol 220-221 ◽  
pp. 230-238
Author(s):  
Stanisław Laber ◽  
Alicja Laber
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
Friction Force ◽  
Tribological Properties ◽  
Friction Pair ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
The Impact ◽  
Lubricating Properties ◽  
Wear Index

This paper presents the results of research into the effect of the use of an additive to the lubricating oil SAE 15W/40 on the lubricating properties (standardised tests), i.e. the weld point Pz, last non-seizure load Pn, load-wear index Ih, and seizure load Pt. The friction pair consisted of four balls and the tested lubricant. Moreover, the impact of the use of the lubricating oil (non-standardised tests) on tribological properties such as friction force, wear, and the temperature of the friction area for the friction pair C45 steel/210Cr12 steel, was explored. The additive contained copper and lead particles of the size of a few micrometers. The tests helped to determine the effect of the use of the additive to the lubricant on the formation of the operational surface layer. The results were used to build a model of the boundary layer formed as a result of the additive to the lubricating oil.

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.

Polymer spur gears behaviors under different loading conditions: A review

2017 ◽  
Vol 232 (2) ◽  
pp. 210-228 ◽  
Author(s):  
Akant Kumar Singh ◽  
Siddhartha ◽  
Prashant Kumar Singh
Keyword(s):  
Modeling And Simulation ◽  
Polymer Composites ◽  
Tribological Properties ◽  
Failure Modes ◽  
Operating Conditions ◽  
Spur Gears ◽  
Simulation Studies ◽  
Loading Conditions ◽  
Comprehensive Review ◽  
Tooth Modification

The significance of polymer gears to transmit power and motion is increasing continuously due to their inherent characteristics. Polymer gears have established themselves as attractive alternatives to traditional metal gears in plethora applications. They are light in weight, have lower inertia, and run noiseless than their metal counterparts. This article presents a comprehensive review of the research on polymer spur gears operating under low (0–8 Nm) and moderate (>8 and ≤17 Nm) loading conditions. Different polymers and polymer composites used till date for the fabrication of such gears are included along with different operating conditions. Various design features of polymer gears and tooth modification techniques for the improvement of the performance and durability of these gears have also been included in this review. The aspects of the modeling and simulation studies of the polymer gears are also emphasized in this paper for completeness of the review. The concept of hybrid gears is discussed along with their tribological properties. Various methods of manufacturing of polymer gears and their failure modes are discussed so as to make the article useful for researchers.

Development of Antifriction Materials Based on Polytetrafluoroethylene with Carbon Fibers and Tungsten Disulfide

2020 ◽  
Vol 992 ◽  
pp. 745-750
Author(s):  
A.P. Vasilev ◽  
T.S. Struchkova ◽  
A.G. Alekseev
Keyword(s):  
Wear Resistance ◽  
Polymer Composites ◽  
Carbon Fibers ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Relative Elongation ◽  
Tungsten Disulfide ◽  
Degree Of Crystallinity ◽  
Mechanical And Tribological Properties ◽  
The Coefficient Of Friction

This paper presents the results from the investigation of effect the carbon fibers with tungsten disulfide on the mechanical and tribological properties of PTFE. Is carried out a comparison of mechanical and tribological properties of polymer composites PTFE-based with carbon fibers and PTFE with complex filler (carbon fibers with tungsten disulfide). It is shown that at a content of 8 wt.% CF+1 wt.% WS2 in PTFE, wear resistance increases significantly while maintaining the tensile strength, relative elongation at break and low coefficient of friction at the level of initial PTFE. The results of X-ray analysis and investigation of SEM supramolecular structure and friction surfaces of PTFE and polymer composites are presented. It is shown that the degree of crystallinity of polymer composites increases in comparison with the initial PTFE. The images of scanning electron microscope reveal that particles of tungsten disulfide concentrating on the friction surface is likely responsible to a reduction in the coefficient of friction and increase the wear resistance of PTFE-based polymer composites with complex fillers.

Tribology assessment of surface-contact sliding pairs with streak defect under dynamic harmonic excitation loading

2018 ◽  
Vol 70 (3) ◽  
pp. 481-489 ◽  
Author(s):  
Wei Yuan ◽  
Guangneng Dong ◽  
Kwai Sang Chin ◽  
Meng Hua ◽  
Qianjian Guo
Keyword(s):  
Friction Force ◽  
Tribological Properties ◽  
Harmonic Excitation ◽  
Operating Conditions ◽  
Contact Friction ◽  
Weight System ◽  
Discrete Wavelet ◽  
Content Type ◽  
Surface Contact ◽  
Side Flow

Purpose Streak defect and dynamic harmonic excitation (DHE) loading play important roles in machine operating conditions. The purpose of this paper was to assess the effects of streak defect and DHE loading on the tribological properties of surface-contact friction pairs, for example the differential gear end-face on the washer, via experimental investigation. Design/methodology/approach Streak defect was artificially introduced into the washer surface, which was loaded with DHE loads produced by a spring-connecting weight system. The wear scar of the washers and the monitored friction force signals were respectively scanned using scanning electron microscope (SEM) and analyzed using wavelet simulation. Findings The friction force curves, SEM images and discrete wavelet transform results indicate that DHE loading tends to increase friction force, to accelerate plowing damages and result in side-flow of material and plastic deformation on the surfaces of the washer. Whereas, streak oil-channel textures on washer specimen can be machined to modify the lubrication condition in the running-in stage so as to improve the tribological properties of the sliding pairs which were even subjected to DHE loading. Originality/value On the basis of this thesis research, the effect of streak defect and DHE loading on tribological performance of surface-contact sliding pairs is discussed. The results of wear form and friction state with the effect of streak defect and DHE loading facilitate to optimize the operating condition of mechanical parts.

TRIBOLOGICAL PROPERTIES OF GRAPHENE OXIDE-METAL-CARBON COMPOSITES

Tribologia ◽  
2018 ◽  
Vol 281 (5) ◽  
pp. 53-64
Author(s):  
Roksana MUZYKA ◽  
Piotr DUDA ◽  
Zbigniew ROBAK ◽  
Sławomir KAPTACZ ◽  
Sabina DREWNIAK
Keyword(s):  
Wear Resistance ◽  
Graphene Oxide ◽  
Tribological Properties ◽  
Low Voltage ◽  
Structural Characteristics ◽  
Operating Conditions ◽  
Wear Properties ◽  
Graphite Content ◽  
Large Current ◽  
Materials Used

Cu-C composites are materials used for the production of brushes, contacts, and pressing shoes for electric machines due to their mechanical and wear properties. These characteristics include good thermal and electrical conductivity, a low coefficient of friction, and lubricity under varying operating conditions. Currently, graphite and copper nanopowder based materials are used as a metal-carbon material in different ratios of these components. Graphite content in this kind of material has a positive effect on the smaller consumption of, e.g., rings and commutators. In contrast, a material without graphite content is used at high current densities. The examples of such machines are a DC motor starter or generators for electrolysis characterized by large current and low voltage. The present study tested the effect of graphene oxide (rGO) content on tribological properties in contact with steel in Cu-C composites. Tests were conducted on a ball-on-disk apparatus in conditions of dry friction. Disk wear and surface geometrical structure parameters (SGP) of the samples after tribological tests were determined on the basis of measurements made on the Talysurf.3D contact profilometer from Taylor Hobson. Damage mechanisms were identified and their relationships with structural characteristics were deducted. The hardness of Cu-C materials was higher than in copper. Cu-C based materials produce a better improvement of wear resistance, while the wear resistance of the graphene oxide based composites also decreased.

scholarly journals Study of Tribological Properties of Fullerenol and Nanodiamonds as Additives in Water-Based Lubricants for Amorphous Carbon (a-C) Coatings

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 139
Author(s):  
Shuqing Chen ◽  
Qi Ding ◽  
Yan Gu ◽  
Xin Quan ◽  
Ying Ma ◽  
...  
Keyword(s):  
Amorphous Carbon ◽  
Tribological Properties ◽  
Size Range ◽  
Friction Pair ◽  
Asperity Contact ◽  
Low Concentration ◽  
Contact Loads ◽  
Water Based ◽  
The Coefficient Of Friction ◽  
Sufficient Concentration

The tribological performances of fullerenol and nanodiamonds (NDs) as additives in water-based lubricants for amorphous carbon (a-C) coatings are investigated to avoid disadvantage factors, such as chemical reactions and deformation of particles. The effects of size and additive amount on tribological properties of nanoparticles are studied by rigid nanoparticles within the dot size range. The results show that owing to its small particle size (1–2 nm), fullerenol cannot prevent direct contact of the friction pair at low concentration conditions. Only when the quantity of fullerenol increased to support the asperity contact loads in sufficient concentration did nano-bearings perform well in anti-friction and anti-wear effects. Unlike fullerenol, nanodiamond particles with a diameter of about 5–10 nm show friction-reducing effect based on the nano-bearing effects at ultra-low concentration (0.01 wt.%), whereas particles at higher concentration block the rolling movement, hence increasing the coefficient of friction (COF) and wear. As a result of the effect of difference in size, fullerenol provides a better overall lubrication, but it is hard to reach a friction coefficient as low as NDs even under the optimal conditions.

scholarly journals Influence of Contact Plateaus Characteristics Formed on the Surface of Brake Friction Materials in Braking Performance through Experimental Tests

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4931
Author(s):  
Rafael Lucas Machado Pinto ◽  
Juan Carlos Horta Gutiérrez ◽  
Robson Bruno Dutra Pereira ◽  
Paulo Eustáquio de Faria ◽  
Juan Carlos Campos Rubio
Keyword(s):  
Friction Pair ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Performance Measurements ◽  
Friction Materials ◽  
Braking Performance ◽  
Emergency Braking ◽  
The Coefficient Of Friction ◽  
And Performance

This work applies a procedure for analysis and characterization of the surface of brake friction materials, correlating them with the tribological and thermal properties achieved in different vehicle braking conditions. Experiments were performed in a vehicle under two real conditions of braking operation, simulated flat track descent and emergency braking. Characteristics of the plates formed on the surfaces of the friction materials were analyzed by scanning electron microscopy (SEM) and correlated with the performance during braking, as measured by the coefficient of friction at the interface of the friction pair and temperature. As a result, the formation of the primary and secondary plateaus in these two different braking operating conditions was observed, and the relationship between the characteristics of the plateaus formed on the surface and the surface roughness parameters and performance measurements during braking.

Modification of working conditions for a friction pair with an additive added to engine oil during operation

2014 ◽  
Vol 66 (4) ◽  
pp. 560-567
Author(s):  
Alicja Laber
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
Friction Force ◽  
Tribological Properties ◽  
Friction Pair ◽  
Engine Oil ◽  
Friction Process ◽  
Content Type ◽  
Increasing Load ◽  
Wear Index

Purpose – The purpose of this paper is to present the results of research into using an additive to SAE 15W/40 engine oil during operation and its influence on lubricating properties (normalised tests) on weld point Pz, non-seizure load Pn, load wear index Ih and on seizure load Pt. The friction pair consisted of a group of four balls and the tested lubricant. Moreover, the author tested the influence of an additive to engine oil (non-normalised tests) on tribological properties, including friction force, wear and the temperature of friction area for the C45 steel/210Cr12 steel friction joint. She also determined the influence of an additive to engine oil on the formation of the operating surface layer. The research results helped to build the model of the boundary layer that was formed as a result of adding an additive to engine oil. Design/methodology/approach – The lubricant properties of engine oil and engine oil to which an additive was added during operation were determined according to PN-76/C-04147. The following are the indexes of lubricant properties: weld point Pz, load wear index Ih, non-seizure load Pn, seizure load and average scar diameter. The Pz, Pn and Ih indexes were determined at abruptly increasing load to the moment of welding of the friction pair. The Pt index was determined at the increasing load of the friction pair from 0 to 800 daN at the speed of 408.8 N/s. The tests of tribological properties (friction force, wear and the temperature of friction area) were conducted for the C45/210 Cr12 friction pair in the presence of a lubricant and a lubricant with an additive. Findings – The modification of SAE 15W/40 engine oil with the additive added during operation resulted in improved indexes of lubricant properties Pz, Pn, Ih and Pt and average scar diameter. The boundary layer for the modified oil breaks after a longer time and at lesser friction force. The modification of the engine oil reduced the wear of the friction pair. After the friction process, element composition in the surface layer of the wear trace and its distribution were determined in relation to applied lubricants. A significant amount of sulphur, phosphorus and oxygen, as well as an insignificant amount of copper, was observed in the wear trace after the friction process in the presence of the lubricant medium. The distribution of elements in the wear trace when the engine oil with the additive was used is steady in the wear trace and outside it. Some sulphur, phosphorus and chlorine were found in the wear trace. Originality/value – The results of tests on tribological properties (non-normalised tests) confirmed the positive affect of the additive to engine oil on lubricant properties (normalised tests). The modification of the engine oil caused reduced friction force and the reduced wear of the friction pair. The reduction of friction force and wear was the result of the formation of the surface of a greater amplitude density of unevenness tops in the friction process. Moreover, the operating surface layer, created in the friction process when the additive was added to the engine oil, had greater load participation at 50 per cent C. This operational surface layer improved tribological properties, i.e. it reduced value of friction force and wear. The test results were used to build a model of the boundary layer created as a result of the additive added to engine oil.

scholarly journals Conventional and unconventional materials used in the production of brake pads – review

2020 ◽  
Vol 27 (1) ◽  
pp. 374-396
Author(s):  
Andrzej Borawski
Keyword(s):  
New Technologies ◽  
Friction Pair ◽  
Brake Pad ◽  
Operating Life ◽  
Friction Resistance ◽  
Brake Pads ◽  
Disc Brakes ◽  
The Coefficient Of Friction ◽  
Grey Cast ◽  
Materials Used

AbstractBrakes are one of the most important components of vehicle. The brake system must be reliable and display unchanging action throughout its use, as it guards the health and life of many people. Properly matched friction pair, a disc and brake pad (in disc brakes), have a great impact on these factors. In most cases, the disc is made of grey cast iron. The brake pads are far more complex components. New technologies make it possible to develop materials with various compositions and different proportions, and connect them permanently in fully controllable processes. This elaboration shows that all these factors have a greater or lesser impact on the coefficient of friction, resistance to friction wear and high temperature, and brake pad’s operating life. This review collects the most important, the most interesting, and the most unconventional materials used in production of brake pads, and characterizes their impact on the tribological properties of pads.

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