Effect of contact stress on the tribology behaviors of PTFE/316L seal pairs under various abrasive-contained conditions

2020 ◽  
pp. 135065012093751
Author(s):  
Ming-xue Shen ◽  
Bo Li ◽  
De-hui Ji ◽  
Xiao-Rong He ◽  
Xiu-zhou Lin ◽  
...  
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Contact Stress ◽  
Wear Mechanism ◽  
Considerable Effect ◽  
Contact Stresses ◽  
The Coefficient Of Friction ◽  
Three Body ◽  
Size Threshold ◽  
Invasion Behavior

This study focuses on the tribological characteristics of polytetrafluoroethylene rubbing against 316L stainless steel in the presence of various Al2O3 abrasive particles. The ranges of the contact stresses and abrasive sizes were 2.50–5.01 MPa and 2.0–230 µm, respectively. The evolution of the coefficient of friction, abrasive invasion behavior and damage characteristics on worn surfaces, and the transformation of damage mechanisms under different contact stresses are summarized. Results demonstrate that contact stress exerts a considerable effect on abrasive invasion behavior, the coefficient of friction trends become complicated at low contact stress. With decreasing particle sizes under a contact stress of 2.50 MPa, the wear failure changes from two-body wear to three-body wear, or two wear behaviors exist simultaneously. As contact stress increases, the wear mechanism is gradually simplified. The particle size threshold that causes the change of the wear mechanism is also gradually reduced. The wear rate of polytetrafluoroethylene has no linear relationship with abrasive size, whereas wear increases with contact stress. Under 2.50 MPa conditions, the particles easily invade the tribo-interface in the friction process, thus increasing the wear rate of the metallic counterpart. In addition, with increases contact stress, the polytetrafluoroethylene material transfers to the counterface, and local adhesion occurs. When the contact stress is increased to 5.01 MPa, polytetrafluoroethylene even shows an obvious creep.

scholarly journals Fretting wear rate of sulphur deficient MoSx coatings based on dissipated energy

2001 ◽  
Vol 16 (12) ◽  
pp. 3567-3574 ◽  
Author(s):  
Xiaoling Zhang ◽  
W. Lauwerens ◽  
L. Stals ◽  
Jiawen He ◽  
J-P. Celis
Keyword(s):  
Relative Humidity ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Contact Stress ◽  
Ambient Air ◽  
Fretting Wear ◽  
Dissipated Energy ◽  
Wear Volume ◽  
The Coefficient Of Friction ◽  
Crystallographic Orientations

The fretting wear of sulphur-deficient MoSx coatings with different crystallographic orientations has been investigated in ambient air of controlled relative humidity. The coefficient of friction and the wear rate of MoSx coatings sliding against corundum depend not only on fretting parameters like contact stress, fretting frequency, and relative humidity, but also strongly on the crystallographic orientation of the coatings. For randomly oriented MoSx coatings, the coefficient of friction and the wear rate increased significantly with increasing relative humidity. In contrast, basal-oriented MoSx coatings were less sensitive to relative humidity. The coefficient of friction of both types of MoSx coatings decreased on sliding against corundum with increasing contact stress and decreasing fretting frequency. A correlation between dissipated energy and wear volume is proposed. This approach allows detection in a simple way of differences in fretting wear resistance between random- and basal-oriented MoSx coatings tested in ambient air of different relative humidity.

Contact Area as a Critical Determinant in the Tribology Of Metal-on-Polyethylene Total Joint Arthroplasty

2005 ◽  
Vol 128 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Daniel Mazzucco ◽  
Myron Spector
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Contact Stress ◽  
Contact Area ◽  
Total Joint Arthroplasty ◽  
Friction And Wear ◽  
Joint Arthroplasty ◽  
Critical Determinant ◽  
The Coefficient Of Friction ◽  
Pin On Disk

The effects of contact area and contact stress on friction and wear of polyethylene-metal articulation were evaluated using a bidirectional pin-on-disk apparatus. A doubling of the contact area under fixed loading conditions led to a 50% increase in the coefficient of friction and a doubling of the wear rate. There appeared to be a relationship between the increase in wear rate and the increase in the coefficient of friction. A model was developed to explain the mechanism by which engagement of asperities results in the increasing wear rate with increasing contact area despite the decreased stress.

Contact Area as a Critical Determinant in the Tribology of Metal-on-Polyethylene Total Joint Arthroplasty

2004 ◽  
Author(s):  
Dan Mazzucco ◽  
Myron Spector
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Contact Stress ◽  
Contact Area ◽  
Total Joint Arthroplasty ◽  
Friction And Wear ◽  
Joint Arthroplasty ◽  
Critical Determinant ◽  
The Coefficient Of Friction ◽  
Pin On Disk

The effects of contact area and contact stress on friction and wear of polyethylene-metal articulation were evaluated using a bi-directional pin-on-disk apparatus. A doubling of the contact area under fixed loading conditions led to a 50% increase in the coefficient of friction and a doubling of the wear rate. There appeared to be a relationship between the increase in wear rate and the increase in the coefficient of friction. A model was developed to explain the mechanism by which engagement of asperities results in the increasing wear rate with increasing contact area despite the decreased stress.

Study on tribological behavior of zinc phosphate impregnated graphite under oil lubrication condition

2021 ◽  
pp. 1-13
Author(s):  
Jianhang Chen ◽  
Siyang Gao ◽  
Peng Wang ◽  
Weihai Xue ◽  
Shu Li ◽  
...  
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Wear Mechanism ◽  
Friction And Wear ◽  
Zinc Phosphate ◽  
Tribological Behavior ◽  
Oil Lubrication ◽  
Rotating Speed ◽  
Nickel Based Superalloy ◽  
The Coefficient Of Friction

Abstract The tribological behavior of zinc phosphate impregnated graphite against nickel-based superalloy (GH4169) in oil environment was investigated, and the lubrication and wear mechanism were also determined in this study. Tribological tests were run under different tribological conditions using a ring-on-disk device. The results showed that, under any load conditions, zinc phosphate impregnated graphite had the lowest coefficient of friction and wear rate at 200 rpm. Under the identical rotating speed condition, the minimum coefficient of friction and wear rate were obtained when the load was 500 N and 1000 N. The lubrication mechanism, which could be reflected by the transfer layer of friction counterpart, was related to the coefficient of friction, wear rate and oil temperature to affect contact characteristics of two solid surfaces and formation ability of liquid film. The wear mechanism of zinc phosphate impregnated graphite under oil lubrication conditions was dominated by abrasive wear and material removal was achieved through the fracture mechanism.

scholarly journals Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Applied Load ◽  
Practical Significance ◽  
Tribological Characteristics ◽  
M 10 ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

Tribological Properties of Polyoxymethylene Composites Against Aluminum

2003 ◽  
Vol 125 (3) ◽  
pp. 661-669 ◽  
Author(s):  
Masaya Kurokawa ◽  
Yoshitaka Uchiyama ◽  
Tomoaki Iwai ◽  
Susumu Nagai
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
High Surface ◽  
Surface Hardness ◽  
Disk Surface ◽  
Optical Microscope ◽  
Transfer Film ◽  
The Other ◽  
The Coefficient Of Friction

Tribological properties of several kinds of polyoxymethylene (POM) composites were evaluated for the purpose of developing a polymeric tribomaterial especially suited for mating with aluminum parts having low surface hardness. POM composites containing small amounts of silicon carbide (SiC), POM/SiC; those containing a small amount of calcium octacosanonoate besides SiC, POM/SiC/Ca-OCA; and the one blended with 24 wt % of polytetrafluoroethylene, POM/PTFE(24); were injection-molded into pin specimens and their tribological properties were tested by means of a pin-on-disk type wear apparatus using an aluminum (A5056) mating disk in comparison with a 303 stainless steel (SUS303) disk. Evaluation was focused on observation of the sliding surfaces of the pin specimens and the mating disks by a scanning electron microscope and an optical microscope together with the measurement of surface roughness. In the case of mating against a SUS303 disk having high surface hardness, all pin specimens did not roughen the disk surfaces even after long time of rubbing. Only POM/PTFE(24) composite obviously made a transfer film on the disk surface, while the other composites made an extremely thin one on it. POM/SiC(0.1)/Ca-OCA(1) composite, containing SiC 0.1 wt. % and Ca-OCA 1 wt. %, was found to show the lowest coefficient of friction and the lowest wear rate forming extremely thin transfer film on the mating disk. On the other hand, against an A5056 disk which has lower surface hardness than that of SUS303 disk, unfilled POM and POM composites except POM/SiC(0.1)/Ca-OCA(1) composite roughened the disk surfaces. However, the sliding surface of the A5056 disk rubbed with POM/SiC(0.1)/Ca-OCA(1) composite was significantly smoother and that of the pin specimen was also quite smooth in comparison with other pin specimens. Further, when each POM composite was rubbed against the A5056 disk, formation of transfer film was not obvious on the disk surfaces. For POM/SiC(0.1)/Ca-OCA(1) composite, the wear rate was the lowest of all POM composites, and the coefficient of friction was as low level as 60 percent of that of unfilled POM, but slightly higher than that of POM/PTFE(24) composite. For POM/SiC(0.1)/Ca-OCA(1) composite, the nucleating effect of SiC and Ca-OCA, which accelerated the crystallization of POM during its injection molding to form a matrix containing fine spherulites, must have resulted in increasing the toughness of the matrix and lowering the wear rate. Also, the lubricant effect of Ca-OCA should have lowered the coefficient of friction of the same matrix for rubbing against aluminum mating disk. POM/SiC(0.1)/Ca-OCA(1) composite was concluded as an excellent tribomaterial for mating with aluminum parts.

Dry Slide Wear Behavior of Graphite and SiC, TiO2 Filled the Unidirectional Glass-Epoxy Composites

2017 ◽  
Vol 25 (3) ◽  
pp. 193-198 ◽  
Author(s):  
A. Madhanagopal ◽  
S. Gopalakannan
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Wear Behavior ◽  
Specific Wear Rate ◽  
Dry Sliding ◽  
Testing Time ◽  
Time Duration ◽  
Sem Images ◽  
Unidirectional Glass ◽  
The Coefficient Of Friction

This study determines the friction and the wear properties of the unidirectional glass epoxy composite with Gr, SiC TiO2 powder by using pin on disk apparatus. This tribological data is obtained in dry sliding condition for a constant sliding time of 30 minutes. Test specimens are prepared using hand lay-up process and by varying the different (2, 5, 7) percentage each of graphite and SiC, TiO2 particles addition for the combination of fiber and matrix. The tests are performed by varying the operating parameters of contact pressure (p) and velocity (v). The composites (2% 5%, and 7%) are worn by dry sliding at the steel counter face under ambient conditions. The coefficient of friction reaches maximum of 0.78 at 2 kg load, 2 m/s velocity with testing time duration of 24 min. whereas 5%, 7% sample shows the coefficient of friction 0.28, 0.25 respectively. The specific wear rate value drops to 0.79 (mm3/N-m×10−6) at 2 kg load at 2 m/s velocity for the 5% specimen. The maximum reduction in the specific wear rate at 3 kg load, 1m/s velocity is 32.7 percentages, 5.63 percentages for the 5,7 percentage specimen compared to 2% specimen for the graphite and SiC, TiO2 particle filled composite specimen respectively. The SEM images are also taken to support the results.

Paper 21: Variations in Friction and Wear between Unlubricated Steel Surfaces

1966 ◽  
Vol 181 (15) ◽  
pp. 16-24
Author(s):  
S. W. E. Earles ◽  
D. G. Powell
Keyword(s):  
Wear Rate ◽  
Mild Steel ◽  
Oxide Layer ◽  
Coefficient Of Friction ◽  
Surface Film ◽  
Frictional Heating ◽  
Subsequent Increase ◽  
Track Condition ◽  
The Coefficient Of Friction ◽  
Steel Disc

Experiments have been conducted in a normal atmosphere using a 0·25-in diameter mild-steel pin specimen sliding on a 10-in diameter mild-steel disc. The ranges of normal force and speed are 0·5–10·4 lbf and 20–190 ft/s respectively. Initially the coefficient of friction is comparatively large, and the wear is of the severe metallic form. However, frictional heating causes rapid oxidation of the surfaces and, if the sliding distance is sufficient, the eventual retention of an oxide layer causes a rapid decrease in the coefficient of friction and the wear rate decreases by 3–4 orders of magnitude. At speeds above about 75 ft/s and loads below about 5 lbf the formation, after several hours' sliding, of a continuous oxide layer on the track causes a further reduction in the pin wear rate. At higher loads and/or lower speeds this track condition is not attained. At speeds of 75 ft/s and above there exists a critical load (the magnitude of which depends on speed) above which periodic removals of the surface film(s) occur producing metallic wear and high friction. However, the subsequent increase in oxidation allows conditions of mild wear to be re-established generally within a few seconds. The steady-state coefficient of friction has been observed to be a function of load1/2 × speed, and periodic surface breakdowns found to occur when load1/2 × speed exceeds 170 lbf1/2 ft/s, the frequency decreasing with increasing load or speed.

Effect of crystal size on the tribological properties of lithium disilicate glass-ceramics sliding against alumina and tungsten carbide spheres

2020 ◽  
Vol 72 (9) ◽  
pp. 1109-1116
Author(s):  
Crislaine da Cruz ◽  
Ivan Mathias ◽  
Mariza Veiga Senk ◽  
Gelson Biscaia de Souza ◽  
Francisco Carlos Serbena
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Glass Ceramic ◽  
Crystal Size ◽  
Glass Ceramics ◽  
Stationary Regime ◽  
Content Type ◽  
Dental Restorations ◽  
The Coefficient Of Friction ◽  
Dental Prosthetics

Purpose Lithium disilicate glass-ceramics (LS2 GC) are widely used as dental prosthetics and dental restorations. Based LS2 GC have hardness and translucency similar to that of natural teeth. This study aims to investigate the tribological features of LS2 GC with crystalline volume fraction of 64% and different crystal sizes from 8 µm to 34 µm for different counterparts. Design/methodology/approach The tribological behavior was investigated using a pin-on-disc tribometer with alumina and tungsten carbide (WC) spheres, applied load of 5 N and sliding speed of 5 cm/s at normal conditions. The coefficient of friction was measured continuously up to 10,000 sliding cycles. The specific wear rate was calculated from tribological and profile measurements. The wear mechanism was investigated by surface morphology analysis. Findings The coefficient of friction during running-in varied from 0.8 to 1.0 for the alumina counterpart, because of severe wear. Afterwards, it reduced and reached a stationary regime, characterized by a mild wear regime and the formation of a tribolayer formed by the debris. For the WC counterpart, the coefficient of friction curves increased initially with sliding cycles up to a stationary regime. The samples tested against WC presented the lowest specific wear rate (k), and no variation of wear rate with crystal size was observed. For samples tested against the alumina, crystallization and crystal size increased the wear resistance. Originality/value This study evaluated the effect of different counterfaces on the tribological properties of the LS2 GC, an important glass-ceramic base for many dental prosthetics and dental restorations, discussing results in light of the contact mechanics. Different specific wear rates, wear regimes and dependence on the glass-ceramic microstructure were observed depending on the counterpart. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0352/

Study on the effects of nano-aluminum-oxide particulates on mechanical and tribological characteristics of chopped carbon fiber reinforced epoxy composites

2015 ◽  
Vol 231 (4) ◽  
pp. 403-422 ◽  
Author(s):  
Kali Dass ◽  
SR Chauhan ◽  
Bharti Gaur
Keyword(s):  
Carbon Fiber ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Epoxy Composites ◽  
Specific Wear Rate ◽  
Tribological Characteristics ◽  
X Ray ◽  
The Coefficient Of Friction ◽  
Mechanical And Tribological Characteristics

An experimental study has been carried out to investigate the mechanical and tribological characteristics of chopped carbon fiber (CCF) reinforced epoxy composites filled with nano-Al2O3 particulates, as a function of fiber and filler contents. The experiments were conducted using a pin-on-disc wear test apparatus under dry sliding conditions. The coefficient of friction and specific wear rate of these composites was determined as a function of applied normal load, sliding velocity, sliding distance, and reinforcement content. The tensile, flexural, and compression strengths of ortho cresol novalac epoxy and chopped carbon fiber (OCNE/CCF) filled composites are found to be within the ranges of 48–58.54 MPa, 115–156.56 MPa, and 48–61.15 MPa. Whereas the tensile, flexural, and compression strengths of OCNE/CCF/Al2O3-filled composites are found to be within the ranges of 96–110 MPa, 176–204.66 MPa, and 72–85.65 MPa, respectively. It has been observed that the coefficient of friction decreases and specific wear rate increases with increase in the applied normal loads. Further increases in the fiber (6 wt%) and particle (3 wt%) contents in the epoxy matrix resulted in a decrease of both the mechanical and tribological properties, but remains above that of the CCF reinforced epoxy composites. The worn surfaces of composites were examined with scanning electron microscopy equipped with energy dispersion X-ray analyzer and X-ray diffraction analysis technique to investigate the wear mechanisms.

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