scholarly journals Wear Behavior of Copper–Graphite Composites Processed by Field-Assisted Hot Pressing

2019 ◽  
Vol 3 (1) ◽  
pp. 29 ◽  
Author(s):  
Qian Liu ◽  
Miguel Castillo-Rodríguez ◽  
Antonio Galisteo ◽  
Roberto Guzmán de Villoria ◽  
José Torralba
Keyword(s):  
Friction Coefficient ◽  
Wear Mechanism ◽  
Hot Pressing ◽  
Normal Load ◽  
Pure Copper ◽  
Wear Testing ◽  
Critical Threshold ◽  
Graphite Composite ◽  
Graphite Content ◽  
Graphite Composites

Copper–graphite composites with 0–4 wt % graphite were fabricated by field-assisted hot pressing with the aim of studying the effect of graphite content on microhardness and tribological properties. Experimental results reveal that hardness decreases with the graphite content. Wear testing was carried out using a ball-on-disc tribometer with a normal load of 8 N at a constant sliding velocity of 0.16 m/s. The friction coefficient of composites decreases significantly from 0.92 to 0.29 with the increase in graphite content, resulting in a friction coefficient for the 4 wt % graphite composite that is 68.5% lower than pure copper. The wear rate first increases when the graphite content is 1 wt %; it then decreases as the graphite content is further increased until a certain critical threshold concentration of graphite, which seems to be around 3 wt %. Plastic deformation in conjunction with some oxidative wear is the wear mechanism observed in pure copper, while abrasive wear is the main wear mechanism in copper–graphite composites.

Effect of Graphite Content on Cu–Ni–Graphite Composite for Use as Switch Slide Baseplate Materials Sliding Against U75V Steel

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Yiran Wang ◽  
Yimin Gao ◽  
Jun Takahashi ◽  
Yi Wan ◽  
Yunqian Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Mechanism ◽  
High Speed ◽  
Sliding Friction ◽  
Rapid Development ◽  
Wear Volume ◽  
Fatigue Wear ◽  
Friction Coefficients ◽  
Graphite Composite ◽  
Graphite Content

Abstract The rapid development of high-speed railways necessitates the development of new materials for switch slide baseplates. In this study, a Cu–Ni–graphite composite, containing 1 wt% to 6 wt% graphite and prepared by powder metallurgy, was used as a potential material. Pin-on-disk wear tests were conducted to measure the sliding friction of the Cu–Ni–graphite composite against U75 V steel. The results showed that the friction coefficients gradually decreased when the graphite content in the composite ranged from 1 wt% to 4 wt% in the composite. When the graphite content was 4 wt%, the friction coefficient reached the minimum value (0.153). When the graphite content was low (1 wt% to 4 wt%), the primary wear mechanism was microcutting. An increased graphite content facilitated the generation of lubricating films and decreased the wear damage. As the graphite content increased from 4 wt% to 6 wt%, the friction coefficients also increased. The variation in the wear volume rate had the same tendency as the friction coefficient. When the graphite content exceeded 4 wt%, the primary wear mechanism was delamination and fatigue wear. Due to the tendency to form cracks on the subsurface and the plentiful generation of the spalled pits, the graphite fragments could not completely form lubricating films but separated as wear debris. The lubricating films existing on the U75 V steel were in proportion to the graphite content in the composite. The wear weight loss of the U75 V steel exhibited a reduction with increasing graphite content.

Wear of Spiral Seal Cone Bit in Complex Formations

SPE Journal ◽  
2021 ◽  
pp. 1-16
Author(s):  
Y. Zhou ◽  
J. H. Hu ◽  
B. Tan ◽  
Y. Jiang ◽  
Y. F. Tang
Keyword(s):  
Friction Coefficient ◽  
Working Conditions ◽  
Wear Mechanism ◽  
Testing Machine ◽  
Wear Test ◽  
Simulation Method ◽  
Wear Testing ◽  
Wear Loss ◽  
Wear Depth ◽  
Wear Properties

Summary Sealing is a technical bottleneck that affects drilling efficiency and cost in deep, difficult-to-drill formations. The spiral combination seal with active sand removal performance is a new type of seal, and the wear mechanism is not clear, resulting in no effective design. In this study, the wear properties of materials were measured by a friction-and-wear testing machine, and the measurement methods and criteria of wear loss and friction coefficient were established. The fitting function of working condition and friction coefficient was studied by fitting regression method. The law of influence of working conditions on friction coefficient and wear amount was determined. The actual wear model and evaluation criteria of wear condition were established by using wear test data and geometric relationship. The relationship among working conditions, contact stress, and wear depth is determined by numerical simulation method, and the wear mechanism of the new seal is revealed, which provides a theoretical basis for its application.

scholarly journals Effect of Carbon Content on Friction and Wear Properties of Copper Matrix Composites at High Speed Current-Carrying

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2881
Author(s):  
Zhenghai Yang ◽  
Yuexin Ge ◽  
Xu Zhang ◽  
Bao Shangguan ◽  
Yongzhen Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
High Speed ◽  
Friction And Wear ◽  
Copper Matrix ◽  
Matrix Composites ◽  
Wear Properties ◽  
Wear Area ◽  
Graphite Content ◽  
Arc Erosion ◽  
Graphite Composites

The copper matrix composites were prepared by spark plasma sintering (SPS). The current-carrying friction and wear tests were carried out on a self-made HST-100 high-speed current-carrying friction and wear tester, and the effect of the graphite content on the current-carrying friction and wear properties of the composite material was studied. The results show that with an increase in graphite content, the average friction coefficient and wear rate of the two materials decreased significantly, the fluctuation amplitude of the friction coefficient was also significantly reduced, and the average friction coefficient of copper-coated graphite composite with graphite content of 10 wt.% was 0.100; when the graphite content was the same and more than 5.0 wt.%, the average friction coefficient and wear rate of copper–graphite composites were slightly higher than copper–copper-coated graphite composites; the current-carrying efficiency and current-carrying stability of the copper matrix composite were obviously higher than that of copper material; there was a mechanical wear area and arc erosion area on the wear surface of the composites, with the increase in graphite content, the adherence and the tear of the mechanical wear area weakened, the rolling, plastic deformation increased, and the surface roughness decreased obviously. The surface roughness of the wear surface of copper–copper-coated graphite composites with graphite content of 10 wt.% was 3.17 μm. The forms of arc erosion included melting and splashing, and were mainly distributed in the friction exit area.

Tribological characterization of all-polymer prosthesis based on multi-directional motion

2021 ◽  
pp. 089270572110286
Author(s):  
Xinyue Zhang ◽  
Dekun Zhang ◽  
Kai Chen ◽  
Handong Xu ◽  
Cunao Feng
Keyword(s):  
Friction Coefficient ◽  
Abrasive Wear ◽  
Wear Mechanism ◽  
Friction And Wear ◽  
Quantitative Relationship ◽  
Motion Path ◽  
Aspect Ratios ◽  
Directional Motion ◽  
Motion Paths ◽  
Prosthesis Material

The complex movement of artificial joints is closely related to the wear mechanism of the prosthesis material, especially for the polymer prosthesis, which is sensitive to motion paths. In this paper, the “soft-soft” all-polymer of XLPE/PEEK are selected to study the influence of motion paths on the friction and wear performance. Based on the periodic characteristics of friction coefficient and wear morphology, this paper reveals the friction and wear mechanism of XLPE/peek under multi-directional motion path, and obtains the quantitative relationship between friction coefficient and the aspect ratios of “∞”-shape motion path, which is of great significance to reveal and analyze the wear mechanism of “soft” all-polymer under multi-directional motion path. The results show that the friction coefficient is affected by the motion paths and have periodicity. Morever, under the multi-directional motion paths, the wear of PEEK are mainly abrasive wear and adhesive wear due to the cross shear effect, while the wear of XLPE is mainly abrasive wear with plastic accumulation. In addition, the friction coefficient is greatly affected the aspect ratios Rs-l of “∞”-shape and loads. Meanwhile, the wear morphologies are greatly affected by the aspect ratios Rs-l of “∞”-shape, but less affected by loads.

The Dependence of the Friction Coefficient on the Size and Course of Sliding Speed

2014 ◽  
Vol 693 ◽  
pp. 305-310 ◽  
Author(s):  
Eva Labašová
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Testing Machine ◽  
Current Component ◽  
Sliding Speed ◽  
Rectangular Shape ◽  
Coefficient Increase ◽  
The Coefficient Of Friction ◽  
Ring Method ◽  
Run Up

The coefficient of friction for the bronze material (CuZn25Al6) with insert graphite beds and other bronze material (CuSn12) are investigated in this paper. Friction coefficient was investigated experimentally by the testing machine Tribotestor`89 which uses the principle of the ring on ring method. The external fixed bushing was exposed to the normal load of the same size in all tests. Process of load was increased from level 50 N to 600 N during run up 300 s, after the run up the appropriate level of load was held. The internal bushing performed a rotational movement with constant sliding speed. The value of sliding speed was changed individually for every sample (v = 0.2 (0.3, 0.4) m.s-1). The forth test had a rectangular shape of sliding speed with direct current component 0.3 m.s-1 and the amplitude 0.1 m.s-1 period 300 s, the whole test took 2100 s. The obtained results reveal that friction coefficient increase with the increase of sliding speed.

Piston Ring-Cylinder Bore Friction Modeling in Mixed Lubrication Regime: Part II—Correlation With Bench Test Data

1999 ◽  
Vol 123 (1) ◽  
pp. 219-223 ◽  
Author(s):  
Ozgen Akalin ◽  
Golam M. Newaz
Keyword(s):  
Friction Coefficient ◽  
Test Data ◽  
Piston Ring ◽  
Normal Load ◽  
Test System ◽  
Mixed Lubrication ◽  
Contact Temperature ◽  
Bench Test ◽  
Crank Angle ◽  
Contact Width

A bench friction test system for piston ring and liner contact, which has high stroke length and large contact width has been used to verify the analytical mixed lubrication model presented in a companion paper (Part 1). This test system controls the speed, temperature and lubricant amount and records the friction force, loading force, crank angle signal and contact temperature data simultaneously. The effects of running speed, applied normal load, contact temperature and surface roughness on friction coefficient have been investigated for conventional cast-iron cylinder bores. Friction coefficient predictions are presented as a function of crank angle position and results are compared with bench test data. Analytical results correlated well with bench test results.

scholarly journals Experimental Study on the Transition between Static and Kinetic Frictions of Steel/Shale Pairs

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qin Lian ◽  
Chunxu Yang ◽  
Jifei Cao
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Critical Distance ◽  
Dynamic Friction ◽  
Stick Slip ◽  
Dynamic Friction Coefficient ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Stick Slip Motion ◽  
Insight Into

The transition between static and kinetic frictions of steel/shale pairs has been studied. It was found that the coefficient of friction decreased exponentially from static to dynamic friction coefficient with increasing sliding displacement. The difference between static and dynamic friction coefficients and the critical distance Dc under the dry friction condition is much larger than that under the lubricated condition. The transition from static to dynamic friction coefficient is greatly affected by the normal load, quiescent time, and sliding velocity, especially the lubricating condition. Maintaining continuous lubrication of the contact area by the lubricant is crucial to reduce or eliminate the stick-slip motion. The results provide an insight into the transition from static to dynamic friction of steel/shale pairs.

Effect of Sliding Speed on Tribological Properties of Microwave Sintered Copper-Graphite Composites

2014 ◽  
Vol 592-594 ◽  
pp. 1305-1309 ◽  
Author(s):  
K. Rajkumar ◽  
S. Aravindan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dry Sliding ◽  
Graphite Layer ◽  
Sliding Speed ◽  
Graphite Content ◽  
Sintered Copper ◽  
Pin On Disc ◽  
Graphite Composites ◽  
Scanning Electron

Effects of graphite content, and sliding speed on the tribological characteristics of copper-graphite composites under dry sliding condition were evaluated using a pin-on-disc tribometer. The worn surfaces of the composites were analyzed through Scanning Electron Microscopy (SEM). The experimental results revealed the improvement in wear resistance with increasing graphite content. The friction coefficient is also gradually decreasing upto 25 vol% graphite. Sliding speed has an effect on copper (5-15 vol%) graphite composites where as sliding speed has no effect in copper-(20-30 vol%) graphite composites. This difference is attributed to availability of self-lubricating graphite layer at the contact zone.

Sign in / Sign up

Export Citation Format

Share Document