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.

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.

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.

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.

A Global Tribological Approach of Friction Dry Contact Polymer with SGF on Steel, in Terms of Consequences on Metallic Surface Condition (Comparative Wear Coefficients of Steel Surface)

2015 ◽  
Vol 723 ◽  
pp. 927-942 ◽  
Author(s):  
Virgil Florescu ◽  
Lucian Capitanu ◽  
Dorin Rus
Keyword(s):  
Friction Coefficient ◽  
Steel Surface ◽  
Plastic Material ◽  
Normal Load ◽  
Contact Temperature ◽  
Metallic Surface ◽  
Linear Wear ◽  
Sliding Speed ◽  
Dry Contact ◽  
Steel Surfaces

In this paper, we present a global tribological approach of friction dry contact polymer with SGF on steel, in terms of consequences on metallic surface condition (comparative wear coefficients of polished steel surface) based on extensive experimental determinations between the value and the evolution of the friction coefficient, wear of steel surfaces and contact temperature, in the case of linear dry contact, for thermoplastic material reinforced with short glass fibers (SGF) and various steel surfaces. The aim was to highlight the evolution of the wear process depending on the friction coefficient, as well as the dependence of the loading wear and the sliding speed. Wear depth and volume were calculated based on the “wear imprint” method. As a result, it was possible to graphically illustrate the evolution of the friction coefficient, of the contact temperature, and the change of the wear process, emphasizing the abrasive, adhesive and corrosive wear. The evolution of the plastic material transfer function of the contact temperature, namely of the power lost by friction was highlighted. It has been demonstrated that in the case of a 30% SGF content it can reach and even exceed contact temperatures very close to the yield limit of the plastic material. The influence of the normal load and sliding speed was evaluated in detail. The influence of SGF content, normal load, relative sliding speed and contact temperature over the metal surface wear and over the nature of wear mechanism was recorded. The reaction to wear of different steel surfaces in linear dry friction contact on polymers with SGF (polyamide + 20% SGF, polyamide + 30% SGF and polycarbonate with 20% SGF), observing the friction influence over the metallic surfaces wear. The paper includes also its analysis over the steel’s wear from different points of view: the reinforcement content influence and tribological parameters (load, contact pressure, sliding speed, contact temperature, etc.). Thus, authors' findings related to the fact that the abrasive component of the friction force is more significant than the adhesive component are presented, which generally is specific to the polymers’ friction. Authors’ detections also state that, in the case of the polyamide with 30% glass fibres, the steel surface linear wear rate order are of 10-4mm/h, respectively the order of volumetric wear rate is of 10-6cm3/h. The resulting comparative volumetric wear coefficients are of the order (10-11to 10-12) cm3/cm and respectively linear wear coefficients of 10-9mm/cm.

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.

Experimental study on the relationship between the friction coefficient and interference in locomotive axle press-fitting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ting Wang ◽  
Hanfei Guo ◽  
Jianjun Qiao ◽  
Xiaoxue Liu ◽  
Zhixin Fan
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Friction Pair ◽  
Rolling Stock ◽  
Content Type ◽  
Press Fitting ◽  
The Press ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Locomotive Wheels

PurposeTo address the lack of data in this field and determine the relationship between the coefficient of friction and the interference between locomotive wheels and axles, this study evaluates the theoretical relationship between the coefficient of friction and the interference under elastic deformation.Design/methodology/approachWhen using numerical analyses to study the mechanical state of the contacting components of the wheels and axle, the interference between the axle parts and the coefficient of friction between the axle parts are two important influencing factors. Currently, as the range of the coefficient of friction between the wheel and axle in interference remains unknown, it is generally considered that the coefficient of friction is only related to the materials of the friction pair; the relationship between the interference and the coefficient of friction is often neglected.FindingsA total of 520 press-fitting experiments were conducted for 130 sets of wheels and axles of the HXD2 locomotive with 4 types of interferences, in order to obtain the relationship between the coefficient of friction between the locomotive wheel and axle and the amount of interference. These results are expected to serve as a reference for selecting the coefficient of friction when designing axle structures with the rolling stock, research on the press-fitting process and evaluations of the fatigue life.Originality/valueThe study provides a basis for the selection of friction coefficient and interference amount in the design of locomotive wheels and axles.

The Influence of Surface Texture on Abrasive Wear

2019 ◽  
Vol 823 ◽  
pp. 33-40 ◽  
Author(s):  
Yu Tong Hu ◽  
Yong Yong He ◽  
Wei Wang
Keyword(s):  
Friction Coefficient ◽  
Femtosecond Laser ◽  
Abrasive Wear ◽  
White Light ◽  
Surface Texture ◽  
Friction Surface ◽  
Surface Texturing ◽  
Experimental Results ◽  
The Relationship ◽  
Main Factor

Friction happens everywhere. Abrasives generated in tribological process will result in secondary wear. Abrasive wear is a kind of rather common but harmful wear, which is the main reason for the damage of fifty-percent mechanical components by friction. Surface texturing is an effective method to improve the tribological and lubricating performance of tribo-pairs. In this paper, with different-size diamond particles added into the lubricant and a surface of the tribo-pairs textured by different parameters (diameter and depth) with femtosecond laser, the relationship between the surface texture and the abrasive wear was researched, and the influence of the texture on the abrasive wear was analyzed. The friction experiments were carried out on UMT3. The microstructures were tested and analyzed by SEM, microscope and White Light Interferometer respectively. The experimental results showed that the size of the surface texture, compared with that of abrasives, is the main factor which determines the friction coefficient. As the size of the surface texture is much bigger than that of the abrasives, the texture can accommodate the abrasives efficiently, and thus the friction coefficient is reduced efficiently.

scholarly journals Friction surface modifiers of carbon-containing material for high-temperature operation

2021 ◽  
Vol 2124 (1) ◽  
pp. 012013
Author(s):  
M N Roshchin
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Friction Coefficient ◽  
Friction Surface ◽  
Atmospheric Conditions ◽  
Temperature Range ◽  
Tribological Tests ◽  
Surface Modifiers ◽  
Antifriction Properties ◽  
High Temperature Operation

Abstract The results of high-temperature tribological tests of carbon-containing material in friction on heat-resistant stainless steel 40X13 in the temperature range from 20 to 700 °C under atmospheric conditions are presented. Friction surface modifiers “Argolon-2D” material improve antifriction properties and decrease friction coefficient value. Friction coefficient when using Ni-Se-PTFE modifier at load of 0.67 MPa and speed of 0.16 m/s is less by 5% than at speed of 0.05 m/s, and at speed of 0.25 m/s friction coefficient is less by 13% than at speed of 0.05 m/s. At 500 °C and a load of 0.67 MPa the friction coefficient when using Ni-Se-PTFE modifier is 30% higher than when using InSb-PTFE modifier, and the friction coefficient when using CuO-PTFE modifier is 1.2 times higher than when using InSb-PTFE modifier.

EXPERIMENTAL AND NUMERICAL STUDY OF THERMAL ANALYSIS OF HIGH-SPEED FRICTION BRAKING SYSTEM

2011 ◽  
Vol 10 (01) ◽  
pp. 135-142
Author(s):  
CHUNMEI ZHANG ◽  
YONGFENG LI
Keyword(s):  
Thermal Analysis ◽  
Friction Surface ◽  
High Speed ◽  
Material Selection ◽  
Numerical Study ◽  
Friction Pair ◽  
Maximum Temperature ◽  
Dimensionless Time ◽  
Braking System ◽  
Friction Braking System

Thermal analysis can be used as one of the basis for the friction pair material selection in high-speed friction braking system. In this study, the experimental results showed that surface temperature could be reduced by increasing the radius of the friction disk or thermal conductivity coefficient of disk material with stable braking; In the early stage of long braking, the temperature on the friction surface rises rapidly, but further braking does not lead to a significant rise in temperature; In the case of short braking, there is not enough time for the friction surface to reach the critical temperature, and the disk surface reaches the maximum temperature at the end of braking. During long braking, the dimensionless time capacity of the friction surface reaching the highest temperature is F0 ≈ 0.1F0s.

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