Tribological Performance of PTFE Composites Filled with Spherical-Graphite

2011 ◽  
Vol 197-198 ◽  
pp. 1184-1187
Author(s):  
Jian Wei Sun ◽  
Li Qin Wang ◽  
Le Gu

The tribologcial performance of PTFE composites filled with different contents of spherical-graphite and Flake-graphite were comparatively evaluated on MM-200 test rig in block-on-ring configuration under dry condition. The microstructures of worn surfaces of PTFE composites were examined with SEM, and wear mechanisms was also analyzed. The changes of notched impact strength with the content changed were also considered. The results show that the tribological performance of spherical-graphite was better than flake-graphite with same weight filled: The friction coefficient of spherical-graphite, about 0.10~0.15, was under flake-graphite, about 0.12~0.18; the wear rate of spherical-graphite was lower than flake-graphite at each content. Notched impact strength of spherical-graphite was from 7.0kJ/m2 to 8.7 kJ/m2 with the content increased, while flake-graphite was fall rapidly from 8.5kJ/m2 to 3.0kJ/m2 with the content added more than 5wt. %.

Author(s):  
LiQin Wang ◽  
JianWei Sun ◽  
Le Gu

The tribological performance of Polyetherimide (PEI) composites filled with different Polytetrafluoroethylene (PTFE) content was comparatively evaluated on MM-200 test rig in block-on-ring configuration under dry friction condition. The microstructures of worn surfaces, fractured surfaces and wear mechanisms of the PEI composite were examined under scanning electron microscope (SEM). The variations of elastic modulus and surface hardness with variation in composition were also investigated. The results showed that under conditions of dry friction the PTFE can lower the friction coefficient and reduce wear of the PEI composites. When filled with 10 wt. % PTFE, the composite had the lowest wear rate. For PEI filled with 5wt. % PTFE the friction coefficient was about 0.3 and remained comparatively stable with increase of the PTFE content.


2011 ◽  
Vol 418-420 ◽  
pp. 368-372
Author(s):  
Li Qin Wang ◽  
Jian Wei Sun ◽  
Le Gu

The tribological performances of mixed PTFE-based composites were evaluated on the MM-200 block-on-ring test rig under dry friction condition. The following filler contents: carbon fiber (CF), flake graphite (FG) and spherical graphite (SG) were adopted to investigate their effects on the tribological performances of the composites. The experiments were carried out by a four levels orthogonal table-L16(43), and the experiment data were deal with the methods of range and variance analysis. The results shown that all the filler contents could reduce wear, and the wear rate was stable when the content of fillers were more than 10 wt.%. The degrees of three fillers affecting the wear of composites were CF>FG>SG, and that affecting the friction coefficient were SG>CF>FG. The friction coefficient decreased with increasing the contents of SG, increased with that of CF, first decreased and then increased with that of FG. When the contents of FG is 15 wt.%, the friction coefficient is the lowest. The main worn form was adhesion wear.


2010 ◽  
Vol 654-656 ◽  
pp. 2763-2766 ◽  
Author(s):  
Li Wen Mu ◽  
Xin Feng ◽  
Yi Jun Shi ◽  
Huai Yuan Wang ◽  
Xiao Hua Lu

The tribological properties of polyimide (PI) composites reinforced with graphite or MoS2 sliding in liquid alkali and water as well as dry friction were investigated using a ring-on-ring tester. The results show that the friction coefficient (μ) and wear rate (W) for both graphite/PI and MoS2/PI composites in different liquid mediums are μdry>μwater >μalkali and Wwater>Wdry >Walkali. Results also indicate that the friction coefficient and wear rate of the PI composites filled with different solid lubricants are μMoS2 >μgraphite and W MoS2 >Wgraphite in different liquid mediums. In addition, the hydrophobic inorganic fillers are fit for the reinforcement of polymer-based composites sliding in liquid mediums. It is also concluded from the authors’ work that the wear rate and friction coefficient of polymer-based (such as PI, PTFE) composites in the alkali lubricated conditions is lowest among all the friction conditions. This may be attributed to the ionic hydration in the alkaline solution.


2018 ◽  
Vol 55 (1) ◽  
pp. 102-110 ◽  
Author(s):  
Marian Bastiurea ◽  
Dumitru Dima ◽  
Gabriel Andrei

Graphene oxide and graphite filled polyester composites were prepared by using conventional melt-mixing methods in order to improve tribological performance of polyester. It was investigated friction stability, microhardness, friction coefficient, and specific wear rate of the composites in details. It was found that the presence of graphite and graphene oxide influenced friction coefficient and wear rate of the composites. Graphene oxide decreased wear rate with increasing of test speed and graphite decreased wear rate for composite for all speeds. Tribological performance of the polyester/graphene composites is mainly attributed to bigger thermal conductivity for graphene, which can easily dissipate the heat which appears during the friction process at bigger forces. The positive influence of graphite on coefficient of friction (COF) of the composites is the result of the clivage of graphite layers during the loadings due to van der Waals weak bonds between the graphite layers.


2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Dongya Zhang ◽  
Zhongwei Li ◽  
Feng Gao ◽  
Xian Wei ◽  
Yuquan Ni

Abstract In this study, composite coatings of polyvinylidene fluoride (PVDF) and epoxy resin deposited with La2O3 and MoS2 nanoparticles on the surface of a Babbitt alloy have been studied in order to improve its tribological performance. A pin-on-disc tribometer was used to evaluate the tribological properties of the Babbitt alloys with and without the composite coatings. The results showed that compared with the polymer-La2O3 composite coating, the polymer-MoS2 composite coating was more effective in reducing the friction coefficient and the wear rate of the Babbitt substrate under both dry and boundary lubrication conditions compared with the polymer-La2O3 composite coating. However, the wear rate of the Babbitt alloy with the polymer-La2O3 composite coating was lower than that of the alloy with the polymer-MoS2 composite coating. The wear scratches were analyzed using a scanning electron microscope (SEM). The worn surface of the polymer-La2O3 coating was much smoother and more continuous than that of the polymer-MoS2 coating, meanwhile transfer films were respectively detected on the pin surfaces. The addition of nanoparticles can reduce the wear rate and friction coefficient of polymer composite coating by forming a transfer film. Hence, the polymer composite coating can protect the Babbitt substrate.


2008 ◽  
Vol 403 ◽  
pp. 115-116
Author(s):  
Qian Liu ◽  
Lin Hua Gui ◽  
Jun Hu Meng ◽  
Zhi Feng Li

A considerable test was made to figure out the effects of temperature and sliding conditions on the wear properties of the translucent Dy--Sialon. The friction coefficient was 0.54 at RT, 0.26 at 100 oC, and 0.81 at 600 oC respectively under an applied load of 5N. The wear rate was 6.91×10-15 at RT and 1.0×10-15 at 100 oC for the same Dy--Sialon sample. Obviously Dy-Sialon shows an excellent wear resistance under a suitable sliding condition, a load of 5N and at 100 oC. This appears attractive and important for Dy-Sialon ceramics to be used as a type of special wear resistant materials, with an optical translucence.


2020 ◽  
Vol 72 (10) ◽  
pp. 1159-1165
Author(s):  
Yanfeng Han ◽  
Lei Yin ◽  
Guo Xiang ◽  
Guangwu Zhou ◽  
Haizhou Chen ◽  
...  

Purpose The tribological behavior, i.e. friction coefficient and wear rate, and vibration characteristics of the water-lubricated bearing was investigated. The water-lubricated bearing is made of three different materials, i.e. polyether-ether-ketone (PEEK), polyimide (PI) and nitrile-butadiene rubber (NBR). Design/methodology/approach The tribological behavior was investigated experimentally on a specially designed test rig. Three vibration sensors were used to record the vibration of the bearing. Findings The results indicated that the variation of friction coefficient with rotation speed agrees well with the trend of Stribeck curve. The tested friction coefficient of rubber bearing is higher than that of the other two bearings whether it is in the state of mixed-lubrication or hydrodynamic lubrication, and which causing a larger wear rate in rubber bearing. The PEEK bearing exhibits the best tribological properties due to it has smaller friction coefficient and wear rate. However, it can be found that the rubber bearing gives the minimum vibration acceleration, which means that the rubber bearing has the most potential to improve the stability of water-lubricated bearing rotor system. Originality/value In this study, a group of experiment studies conducted on a specially designed test rig. The comprehensive performance, including friction coefficient, vibration acceleration and wear rate, of water-lubricated bearing with three different materials, i.e. PEEK, PI and NBR, was compared systematically. The experiment research may offer a reference for the selection of material in water-lubricated bearing in specific operating conditions. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0447/


2013 ◽  
Vol 461 ◽  
pp. 415-420
Author(s):  
Jie Peng ◽  
Yu Cheng Liu ◽  
Zhi Feng Yan ◽  
Bao Gang Wang ◽  
Fu Dong Lin ◽  
...  

The friction materials have many species and they are being used widely, but people have higher requests to friction materials along with the development of technology. the friction material of this expermental optimization formula have the advantages of suitable and stable friction coefficient under high temperature, low wear rate, good restoration characteristics and so on. It can effcetively reduce heat fade of friction and wear under high temperature barking. fricton and wear performance of friction material with second adhesive is better than common preparation friction material , it has higher friction coefficient and lower wear rate, It was determined by physical chemical properities of tin and sulfer. while heating or wearing, the temperature of friction material reach melting temperature of tin, it will become molten state, and sulfer has strong oxidation, on the one hand, tin and sulfer occurred chemical reaction, generating sulfide, stannous (one sulfide tin),on the other hand, while the sulfer is being molten state, it will absorb some abrasive dust, at the same time of generating sulfide, abrasive dust will be adsorb and solidify to pits of friction surface, forming abrasive dust membrane, let the friction coefficient of sample become stable rapidly, reducing the wear rate of friction material.


2013 ◽  
Vol 461 ◽  
pp. 407-414
Author(s):  
Sheng Sheng Ma ◽  
Yu Cheng Liu ◽  
Jie Peng ◽  
Xing Wang Chai ◽  
Bao Gang Wang ◽  
...  

This paper experimentally investigated the friction, wear performance, density, hardness and impact performance of pelletizing friction material. The research was used partly granulation process for prepare friction material. Experiments showed that: When the proportion of partly granulation friction material and powder was mixed with 2:1, the friction coefficient was better, which compared to 1:1 and 1:2. The friction coefficient of partly granulation friction material was higher than the powder friction material, and it also increase along with the temperature rise. The best friction material was made by diameter particle mixed the powder with 2:1, of which particle in diameter of 1-10mm. Without the particle diameter of 1-3mm, the friction material wear rate was lower than when the other diameter levels particle and powder were mixed with 2:1. The wear rate of the partly granulated friction material reduced by 10.9-39.47%, which compared to ungranulated friction material. Furthermore, the friction material that was the mixture of powder and particles, the impact strength will decrease following the increasing proportion. At the same range, the impact strength was relatively large when the particles and the powder was mixed with 1:2. The minimum impact strength was 0.0984J cm2 which the particle diameter was 8-10mm and the ratio was 2:1. The friction material density first increased and then decreased as the particle size increasing. The density whose granules and powders ratio was 1:2 was greater than the density between 1:1 and 2:1 at the same level. The minimum density,which occured in 8-10mm particle friction material, was 1.101659 g/cm3. The hardness of part of the granulated friction material increases as the particles size increases, but the range is limited. The hardness value is 102HRR of the maximum hardness of the friction material, which made with 8-10mms diameter particle and powder that ratio was 2:1, The minimum hardness is 80HRR. The friction material formed by mixing particles and the powder occurred rough surface and obvious porosity and a crack after the abrasion test. When the ration was 1:1 and 1:2, the surface scratched obviously, emerged cutting and furrows. The results showed that when Granules and powder mixed with 2:1, the worn surface of the sample is relatively flat. It also showed the main wear form of the friction material was abrasive wear and fatigue wear.


Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1731
Author(s):  
Cheng Liu ◽  
Meijuan Li ◽  
Qiang Shen ◽  
Haikun Chen

In order to improve the tribological properties of epoxy (EP), EP composites were prepared by filling different proportions of silicon carbide (SiC) particles and molybdenum disulfide (MoS2) powder. SiC and MoS2 particle surfaces were modified by the silane coupling agent KH560 to improve dispersion and avoid agglomeration of the inorganic particles in the EP resin matrix. The effect of different proportions of modified MoS2 content on the tribological properties of SiC/EP composites, and the wear mechanism of the worn surface, were investigated when the filler content was fixed at 55 wt.%. The results indicate that the friction and wear properties of modified MoS2/SiC/EP composites are better than SiC/EP composites without modified MoS2. When the modified MoS2 content is 4 wt.%, the average friction coefficient and volume wear rate of the modified MoS2/SiC/EP composite are 0.447 and 14.39 × 10−5 mm3/N·m, respectively, which is reduced by 10.06% and 52.13% in comparison with that of the 55 wt.% SiC/EP composite. Furthermore, the average friction coefficient of a composite containing 4 wt.% MoS2 is 16.14% lower, and the volume wear rate is 92.84% lower than that of pure EP.


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