scholarly journals Tribological Behavior of Polymers and Polymer Composites

2020 ◽  
Author(s):  
Lorena Deleanu ◽  
Mihail Botan ◽  
Constantin Georgescu
Keyword(s):  
Friction Coefficient ◽  
Tribological Behavior ◽  
Glass Beads ◽  
Linear Wear ◽  
Neat Polymer ◽  
Linear Wear Rate ◽  
Test Parameters ◽  
Order Of Magnitude ◽  
Contact Durability

This chapter means to explain the tribological behavior of polymer-based materials, to support a beneficial introducing of those materials in actual applications based on test campaigns and their results. Generally, the designers have to take into consideration a set of tribological parameters, not only one, including friction coefficient, wear, temperature in contact, contact durability related to application. Adding materials in polymers could improve especially wear with more than one order of magnitude, but when harder fillers are added (as glass beads, short fibers, minerals) the friction coefficient is slightly increased as compared to neat polymer. In this chapter, there are presented several research studies done by the authors, from which there is point out the importance of composite formulation based on experimental results. For instance, for PBT sliding on steel there was obtained a friction coefficient between 0.15 and 0.3, but for the composite with PBT + micro glass beads, the value of friction coefficient was greater. Adding a polymer playing the role of a solid lubricant (PTFE) in these composites and also only in PBT, decreased the friction coefficient till a maximum value of 0.25. The wear parameter, linear wear rate of the block (from block-on-ring tester) was reduced from 4.5 μm/(N⋅km) till bellow 1 μm/(N⋅km) for a dry sliding regime of 2.5…5 N, for all tested sliding velocities, for the composite PBT + 10% glass beads +10% PTFE, the most promising composite from this family of materials. This study emphasis the importance of polymer composite recipe and the test parameters. Also there are presented failure mechanisms within the tribolayer of polymer-based materials and their counterparts.

Dry sliding of composites with PBT matrix and micro glass beads on steel

2014 ◽  
Vol 66 (3) ◽  
pp. 424-433 ◽  
Author(s):  
Constantin Georgescu ◽  
Lorena Deleanu ◽  
Mihail Botan
Keyword(s):  
Friction Coefficient ◽  
Tribological Behavior ◽  
Early Stage ◽  
Normal Load ◽  
Glass Beads ◽  
Polybutylene Terephthalate ◽  
Sem Images ◽  
Neat Polymer ◽  
Content Type ◽  
Sliding Distance

Purpose – This research aims to characterize the tribological behavior of polybutylene terephthalate (PBT) and PBT composites with micro glass beads (MGB) on steel, in dry conditions and on a block-on-ring tester, pointing out the influence of sliding distance and speed. The tribology of PBT and its composites is still in an early stage because this thermoplastic polyester requires accurate technological and thermal treatment. Design/methodology/approach – The composites were produced by ICEFS Savinesti Romania and contain PBT grade Crastin6130NC010 (as supplied by Du Pont), 0.5 […] 1.0 per cent (weight) Relamyd B-2Nf (polyamide grade produced by ICEFS, for a better dispersion of MGB), 1 per cent (weight) black carbon for technological and tribological reasons and different micro glass beads (MGB) concentrations (10.0 and 20.0 per cent weight). Tests were done for different sliding distances (2,500, 5,000 and 7,500 m) and speeds (0.5, 1.0 and 1.5 m/s) and a normal load of 5 N. Findings – The friction coefficient and the wear parameter (as mass loss of polymeric blocks) pointed out a good tribological behavior for these composites. Scanning electron microscope (SEM) images revealed particular aspects of PBT local transfer on steel. Also, 10 per cent MGB in PBT reduces wear, especially for longer distances (75,000 m) and higher speeds (0.5 and 0.75 m/s); the friction coefficient is only slightly increased up to 0.23, being less influenced by the speed and the sliding distance as compared to neat polymer. Originality/value – PBT and PBT composites could become challengers for replacing materials in applications similar to tested ones. Even the neat polymer exhibits a good tribological behavior. The composites have a lower sensibility to higher speeds and sliding distances for the applied load.

scholarly journals Tribology of Polymer Blends PBT + PTFE

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 997
Author(s):  
Constantin Georgescu ◽  
Lorena Deleanu ◽  
Larisa Chiper Titire ◽  
Alina Cantaragiu Ceoromila
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Polymer Blends ◽  
Tribological Characteristics ◽  
Linear Wear ◽  
Processing Temperature ◽  
Polybutylene Terephthalate ◽  
Neat Polymer ◽  
Linear Wear Rate ◽  
Uniform Dispersion

This paper presents results on tribological characteristics for polymer blends made of polybutylene terephthalate (PBT) and polytetrafluoroethylene (PTFE). This blend is relatively new in research as PBT has restricted processability because of its processing temperature near the degradation one. Tests were done block-on-ring tribotester, in dry regime, the variables being the PTFE concentration (0%, 5%, 10% and 15% wt) and the sliding regime parameters (load: 1, 2.5 and 5 N, the sliding speed: 0.25, 0.5 and 0.75 m/s, and the sliding distance: 2500, 5000 and 7500 m). Results are encouraging as PBT as neat polymer has very good tribological characteristics in terms of friction coefficient and wear rate. SEM investigation reveals a quite uniform dispersion of PTFE drops in the PBT matrix. Either considered a composite or a blend, the mixture PBT + 15% PTFE exhibits a very good tribological behavior, the resulting material gathering both stable and low friction coefficient and a linear wear rate lower than each component when tested under the same conditions.

Influence of Additive Chemistry on the Tribological Behavior of Steel/Copper Friction Pairs

2021 ◽  
Author(s):  
Weimin Li ◽  
Huaigang Su ◽  
Yunlong Chen ◽  
Rui Ma ◽  
Gaiqing Zhao ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Boundary Lubrication ◽  
High Performance ◽  
Tribological Behavior ◽  
Tribological Performance ◽  
Copper Oxides ◽  
Wear Volume ◽  
Base Oil ◽  
Lubrication Film ◽  
Order Of Magnitude

Abstract The tribological behavior of boundary lubrication is largely dominated by the anti-wear additives. Here five different anti-wear additives were selected and their tribological properties for a steel-copper contact were investigated. It was found that the tribological performance are highly depending on the anti-wear additive chemistry which determines activity, element compositions of the additive. An amine phosphate anti-wear additive AW 316 exhibit best tribological performance with the lowest mean friction coefficient of 0.082 and smallest wear volume which is more than one order of magnitude smaller than base oil. The friction-reducing order of the tested anti-wear additives are AW 316 > ZDDP > 353 > TCP > [P8888][DEHP] while anti-wear showed similar trend. In addition, the tribological mechanism of AW 316 were also discussed based on surface analysis results, and it was found that an even boundary lubrication film of 10–15 nm which was composed of copper oxides, phosphates, amines was formed on the copper disc and is responsible for its outstanding tribological performances. This study provides fundamental insights of the compatibilities among steel-copper friction pairs and suitable anti-wear additives, which can be beneficial for the development of high performance used for steel-copper friction pairs.

Wear Behavior of Polyester – Carbon Nanotubes Composites under Dry Sliding Ball-on-Flat Reciprocating Test

2015 ◽  
Vol 809-810 ◽  
pp. 1169-1174
Author(s):  
Adrian Cotet ◽  
Luminita Ciupagea ◽  
Dumitru Dima ◽  
Gabriel Andrei
Keyword(s):  
Carbon Nanotubes ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Abrasive Wear ◽  
Wear Behavior ◽  
Multiwall Carbon Nanotubes ◽  
Dry Sliding ◽  
Linear Wear ◽  
Linear Wear Rate ◽  
Multiwall Carbon

Friction coefficient and linear wear rate of polyester-carbon nanotubes composites were investigated through ball-on-flat reciprocating test, under dry sliding contact. Three types of nanoscopic fillers were used: multiwall carbon nanotubes (MWCNT), functionalized multiwall carbon nanotubes (MWCNT-COOH) and singlewall carbon nanotubes (SWCNT), with three values of weight content 0.1, 0.15 and 0.2 wt%. Comparative analysis was done for polyester and its composites tested over 14 m sliding distance, under three values of load, 30 N, 40 N and 50 N. Composites containing MWCNT underwent a decrease in friction coefficient and linear wear rate only in case of 50N loading. An improvement of wear behavior under 50N loading was obtained for the composite with 0.10 wt% functionalized carbon nanotubes. Generally, better values of wear rate at 50 N loading were recorded in case of composites with 0.15 wt% and 0.20 wt% MWCNT and SWCNT, respectively. Optical and electronic investigation of the worn surfaces revealed the occurrence of abrasive, adhesive and fatigue wear. Abrasive wear is due to the hard particles detached from the counterpart which produce scratches and furrows on sliding track. Adhesive wear results when soft particle of polymer are caught and blocked among the asperities of counterpart, and it develops over a local area, being influenced by temperature rise. Fatigue and abrasive wear are responsible for the formation of the 3rd body between contacting parts which affects the friction and wear behavior. Morphological analysis of worn surface showed the rise of transfer film that induces instability of wear parameters.

Effect of Surface Profile Structure on Stability of Friction and Wear

2004 ◽  
Author(s):  
A. Titov ◽  
R. Dubrovsky
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Testing Machine ◽  
Surface Profile ◽  
Friction Testing ◽  
Test Parameters ◽  
Texture Parameters ◽  
Wear Friction ◽  
Profile Characteristics

This paper describes the role of surface texture parameters of bodies in contact on friction coefficient and wear rate. Experiments are done on wear friction testing machine that allows dynamically tracking friction coefficient and wear rate of surfaces in contact under heavy-duty boundary lubrication conditions. Experiments based on conforming steel 4340 -bronze SAE 40 friction couple showed the role of profile characteristics of bodies in contact such as skewness and bearing length ratio. Experimental results demonstrated that for surfaces with similar roughness, waviness and profile parameters, a surface with skewness higher than −1.3 invokes instability in test parameters causing fast climb of friction coefficient and increased mass loss.

scholarly journals The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

Lubricants ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 23 ◽  
Author(s):  
Adam Rylski ◽  
Krzysztof Siczek
Keyword(s):  
Friction Coefficient ◽  
Tribological Behavior ◽  
The Other ◽  
Zro2 Nanoparticles ◽  
Lubrication Mechanism ◽  
Lithium Grease ◽  
Frictional Properties ◽  
The Difference ◽  
Ball On Disc

The aim of the paper was to discuss different effects, such as, among others, agglomeration of selected nanoparticles, particularly those from zirconia, on the tribological behavior of lubricants. The explanation of the difference between the concepts of ‘aggregation’ and ‘agglomeration’ for ZrO2 nanoparticles is included. The factors that influence such an agglomeration are considered. Classification and thickeners of grease, the role of additives therein, and characteristics of the lithium grease with and without ZrO2 additive are discussed in the paper. The role of nanoparticles, including those from ZrO2 utilized as additives to lubricants, particularly to the lithium grease, is also discussed. The methods of preparation of ZrO2 nanoparticles are described in the paper. The agglomeration of ZrO2 nanoparticles and methods to prevent it and the lubrication mechanism of the lithium nanogrease and its tribological evaluation are also discussed. Sample preparation and a ball-on disc tester for investigating of spinning friction are described. The effect of ZrO2 nanoparticles agglomeration on the frictional properties of the lithium grease is shown. The addition of 1 wt.% ZrO2 nanoparticles to pure lithium grease can decrease the friction coefficient to 50%. On the other hand, the agglomeration of ZrO2 nanoparticles in the lithium grease can increase twice the friction coefficient relative to that for the pure grease.

scholarly journals Polymeric Composite Materials of Tribotechnical Purpose with a High Level of Physical, Mechanical and Thermal Properties

2021 ◽  
Vol 15 (4) ◽  
pp. 543-550
Author(s):  
Oleh Kabat ◽  
◽  
Volodymyr Sytar ◽  
Oleksii Derkach ◽  
Kostyantyn Sukhyy ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Silica Gel ◽  
Friction Surface ◽  
Steel Surface ◽  
Friction Pair ◽  
Aromatic Polyamide ◽  
Linear Wear ◽  
Mechanical And Thermal Properties ◽  
Linear Wear Rate ◽  
High Level

Polymeric composites (PC) of tribological applications with a high level of physical, mechanical and thermal properties based on aromatic polyamide and silica gel have been developed. Regularities have been obtained that describe the effect of the filler content in PC on the friction coefficient, temperature on the friction surface and the intensity of linear wear rate of the studied PC-steel friction pair. It was found that the optimal silica gel content in the polymer matrix is 10 wt %. The morphology of the steel surface of friction after friction interaction with PC based on aromatic polyamide and silica gel was studied. The formation of an antifriction film on the steel surface of friction was discovered, which contributes to a decrease in the friction coefficient, temperature on the friction surface, and the linear wear intensity of the studied PC. The influence of the load and sliding speed on the main tribotechnical characteristics of the PC-steel friction pair has been studied. Mathematical laws were derived that describe the influence of the main external factors (load and sliding speed) on the friction coefficient and intensity of linear wear rate of the studied friction pair. Physical, mechanical and thermal investigations of the developed PC were carried out and it was found that the introduction of 10 wt % silica gel contributes to their 5–10 % increase.

scholarly journals Effect of Thickness on Tribological Behavior of Hydrogen Free Diamond-like Carbon Coating

Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 243 ◽  
Author(s):  
Biao Huang ◽  
Qiong Zhou ◽  
Er-geng Zhang
Keyword(s):  
Steady State ◽  
Friction Coefficient ◽  
Internal Stress ◽  
Carbon Coating ◽  
Tribological Behavior ◽  
High Energy ◽  
Diamond Like Carbon ◽  
Lubrication Film ◽  
High Energy Particles

The effects of film thickness on the tribological behavior have been investigated for hydrogen-free diamond-like carbon coating in this paper. The film was deposited on cemented carbide substrate (YG10C) by applying a high power impulse magnetron sputtering (HiPIMS) technique. The reciprocating ball on the disc test was conducted on the film with different thicknesses from 0.66~1.26 μm against the ZrO2 ball. The friction coefficient and wear resistance of the coating with different thickness showed a unimodal change. Numerous defects were observed on the surface of the film with a thickness of 0.66 μm and the wear mechanism was mainly plow-grinding. Therefore, the steady-state friction coefficient reached the maximum value of 0.22. The coating with a thickness of 1.01 μm had a higher sp3 content and a smoother, dense surface. A graphite transfer layer with low shear strength was detected on the ZrO2 ball against the film with a thickness of 1.01 μm, which led to the reduction in friction, thus the steady-state friction coefficient reached the minimum value of 0.10. However, the internal stress of the film increased with increasing thickness due to the distortion of the bond angle of internal structure when the film was bombarded by high-energy particles. The peeling coating was observed under reciprocating sliding, which both played the role of plowing and boundary lubrication film. The steady-state friction coefficient was 0.14 with a coating thickness of 1.26 μm. As a result, the hydrogen-free diamond-like carbon coating with optimized thickness shows a smooth and compact surface, low internal stress, high sp3 content, and better tribological properties.

Preparation of C/C-SiC Brake Materials with Low Cost and High Friction Performance

2009 ◽  
Vol 620-622 ◽  
pp. 421-424 ◽  
Author(s):  
Yong Hui Zhang ◽  
Zhi Chao Xiao ◽  
Jian Feng Yang ◽  
Ji Ping Wang ◽  
Zhi Hao Jin
Keyword(s):  
Friction Coefficient ◽  
Low Cost ◽  
Matrix Composition ◽  
Linear Wear ◽  
Dynamic Friction ◽  
Linear Wear Rate ◽  
Frictional Properties ◽  
Dynamic Friction Coefficient ◽  
The Matrix ◽  
Friction Performance

C/C-SiC brake materials were prepared by improved chemical liquid vaporized infiltration (CLVI) combined with liquid silicon infiltration (LSI) process, which needed less than thirty hours. The microstructure and frictional properties of the material were investigated. The density and porosity of the C/C-SiC brake material were 2.05 g/cm3 and 4.8%, respectively. The average dynamic friction coefficient of the materials was about 0.36, and the friction coefficient was stable. The average linear wear rate was less than 4.7 µm cycle-1 for rotating and stationary disk. The matrix composition and microstructure resulted in the high frictional performances.

Tribological Behavior of PTFE Nanocomposites Reinforced with PBA Grafted Alumina Nanoparticles

2012 ◽  
Vol 184-185 ◽  
pp. 1380-1383
Author(s):  
Yong Ping Niu ◽  
Xiang Yan Li ◽  
Jun Kai Zhang ◽  
Ming Han ◽  
Yong Zhen Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Wear Resistance ◽  
Friction Coefficient ◽  
Tribological Behavior ◽  
Compression Molding ◽  
Alumina Nanoparticles ◽  
Low Friction ◽  
Grafted Nanoparticles ◽  
Scanning Electron

Polybutyl acrylate (PBA) grafted alumina nanoparticles were synthesized. Polytetrafluoroethylene (PTFE) nanocomposites reinforced with PBA grafted nanoparticles were prepared by compression molding. The effects of PBA grafted nanoparticles on the tribological behavior of the PTFE nanocomposites were investigated on a tribometer. The abrasion mechanisms of the PTFE nanocomposites were investigated by scanning electron microscopy (SEM) of the abraded surfaces. The results show that the addition of PBA grafted nanoparticles maintains low friction coefficient and improves the wear resistance of the PTFE nanocomposites.

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