共查询到20条相似文献,搜索用时 15 毫秒
1.
Horst Czichos 《Wear》1983,88(1):27-43
Results of investigations on thermoplastic polymers are presented which can be interpreted by prevailing adhesive or abrasive mechanisms as well as by an overlap of different tribological processes.For polymer-polymer sliding pairs it was found that friction is decisively connected with adhesion. When data on the surface energy of the examined polymers were used, the experimentally determined friction values could be related to the adhesion energies of the different polymer-polymer sliding pairs.For polymer-steel sliding pairs the wear behaviour under prevailing abrasive mechanisms was studied. A relationship was established between the combined stresses in the interfacial area and the tensile or rupture strength of the polymers studied.The tribological behaviour of glass-fibre-reinforced polymers such as polyamides and poly(phenylensulphide) is determined by an overlap of different processes which are influenced by the orientation of the glass fibres with respect to the sliding area rather than by the percentage of the glass fibres added. Different investigation methods, e.g. scanning electron microscopy and energy-dispersive analysis of X-rays, revealed that numerous individual processes such as adhesion, material transfers, retransfers, abrasion, deformation and rupture processes as well as surface fatigue overlap in the complex wear behaviour of glass-fibre-reinforced polymers. 相似文献
2.
The wear behaviour of various copper alloy-steel and polyamide-steel sliding pairs for use in heavily loaded cardan joints was studied on two sliding surface test rigs that were constructed on the basis of practical considerations; the influence of numerous parameters such as surface pressure, lubrication and load oscillation was considered. For comparison with the metallic sliding pairs unfilled and filled or reinforced polyamides were used. Tests were carried out at high surface pressures under conditions of mixed friction using high additive lubricants (oils and greases) with and without contamination. 相似文献
3.
Oier Kaltzakorta Rolf W?sche Manfred Hartelt Andrea Aginagalde Wilson Tato 《Tribology Letters》2012,48(2):209-216
The tribological behaviour of unfilled thermoplastic polyurethane (TPU) and a polymer sphere filled (TPUG) thermoplastic polyurethane have been studied under oscillating sliding condition against cast iron as a counterpart. In the case of unfilled TPU, the wear mechanisms are dominated by particle detachment and roll formation. In principle, TPUG also showed a similar wear mechanism as that of unfilled TPU; in addition, particle pull-out and delamination are also observed. Wear volume of TPUG was significantly higher than that for the unfilled TPU and this is attributed to the different material removal processes taking place in the material during sliding. The polymer spheres as a filler material deteriorated the wear resistance of TPU because of improper adhesion and bonding of filler in the TPU matrix and therefore it contributed to more wear. In case of TPU the friction behaviour was strongly dependant on the temperature and surface roughness of the counter body. The results showed that below the glass transition temperature higher friction values are observed with higher counter body surface roughness. However, above the glass transition temperature, higher friction values are observed with a smoother surface roughness of the counter body. In case of TPUG, the friction behaviour was not significantly dependent on surface roughness of the counter body. 相似文献
4.
《Wear》2004,256(3-4):294-301
Material transfer is an important factor in the sliding behaviour of polymers, as it governs the development of friction and wear in the course of time. However, little is known about the first stages of material transfer. Therefore, measurements were performed with polymers sliding onto steel. The first stages of material transfer were studied with a slider-on-sheet apparatus. The results of these measurements are compared with the results of pin-on-disc measurements. In the latter case, polymer sliding onto polymer was also measured. Polyoxymethylene (POM)-C was chosen as polymer material.Scanning electron microscopy showed that polymer transfer is initiated by mechanical interlocking of metal asperities into the polymer. The resulting debris particles are smeared out during further passages in slider-on-sheet measurements. Pin-on-disc experiments resulted in a less dense transfer layer. Metal asperities can still plough through the polymer surface in pin-on-disc experiments, while ploughing is hindered in slider-on-sheet experiments.The friction coefficients found during pin-on-disc and slider-on-sheet experiments were comparable within the experimental error. The friction coefficient of POM-C sliding against stainless steel starts at a relatively low friction level of about 0.2 and rises to higher values after 20 h of sliding due to material transfer. Such a relatively high friction value was also found when POM-C was slid against POM-C, confirming that the increase in friction found during the experiments against steel was due to material transfer. Pin-on-disc experiments with POM-C sliding against POM-C showed rather large differences in wear rate of the polymer pin. 相似文献
5.
An epoxy‐based nanocomposite containing a low concentration of nanometric TiO2 (4 vol. %), graphite powder (7.21 vol. %), and 2–14 vol. % aramid particles was developed as a coating material. The mechanical and tribological performance of the composites was investigated. The epoxy filled only with TiO2 possessed significantly improved impact strength and flexural properties, whereas the further incorporation of graphite and aramid particles had a deleterious effect on most of the mechanical properties, except the modulus. The tribological behaviour of the composites was tested in sliding and fretting modes. Under sliding conditions, the addition of nanometric TiO2 alone significantly improved the wear resistance and decreased the coefficient of friction compared to the neat epoxy. The sliding wear and friction behaviour was further enhanced with the incorporation of graphite and aramid particles. Contrary to the sliding wear behaviour, the fretting wear and friction behaviour was worse for the epoxy filled only with TiO2, but was significantly enhanced by the incorporation of graphite and aramid particles. The optimum aramid particle content for sliding and fretting wear of the epoxy‐based nanocomposite was determined as 10 vol. %. 相似文献
6.
Vinod K. Jain 《Wear》1983,92(2):279-292
The friction and wear characteristics of acetal reinforced with 25 wt.% of randomly dispersed carbon fibers were investigated and compared with those of the base resin. The addition of carbon fibers to the polymer decreased the coefficient of friction and wear rate for the composite material sliding against a hardened and ground steel disk for extended periods of time. A number of surface topography parameters pertinent to the wear process, i.e. arithmetic average roughness, autocorrelation function, asperity density, tip radius of curvature, distribution of the radii of curvature and heights of asperity peaks, and ordinale heights, were calculated and evaluated for the sliding surface of the disk. The worn surfaces of filled and unfilled polymer pins were examined by scanning electron microscopy to investigate the probable wear mechanism for these materials. It was found that the wear of reinforced polymers proceeds by the pulling-out of the broken and worn fibers. 相似文献
7.
On the wear debris of polyetheretherketone: fractal dimensions in relation to wear mechanisms 总被引:2,自引:0,他引:2
It has been recognized that wear debris contains extensive information about wear and friction of materials. Investigation of wear debris is important for tribological research. In order to find out an effective way that is able to diagnose and predict the wear state of polymers, the authors investigated the relationship between the wear debris morphology and the wear behaviour of the bulk material. Polyetheretherketone (PEEK) was employed as the model material. Its sliding wear and friction properties were measured by means of a pin-on-disc apparatus. At a constant sliding velocity of 1 m s−1, the specific wear rate was independent of load under lower loading conditions (1–4 MPa) but increased with a rise in load under higher loading conditions (4–8 MPa). The coefficient of friction was insensitive to the variation of contact pressure. The possible mechanisms involved were analysed on the basis of the wear debris morphology as well as the wear performance. Fractal geometry, which describes non-Euclidean objects, was applied to the quantitative analysis of the boundary texture of the wear debris due to the fact that the qualitative assessment of the wear debris morphology was not effective enough to reflect the geometrical variation of the fragmental shapes. The experimental results demonstrated that the wear debris were fractals, and could be characterized with the fractal dimensions which were determined by the slit island method. In addition, it was found that the fractal dimension of the wear debris was closely related to the wear behaviour of PEEK, and can be regarded as a measure of wear rate. 相似文献
8.
P. Samyn P. De Baets R. Keresztes L. Zsidai G. Kalacska E. Kislinder M. Kozma 《Lubrication Science》2007,13(2):83-100
Polyamides, polyesters and polyacetals are often used in line contacts under reciprocating or continuous sliding. These contacts are simulated on cylinder‐on‐plate (COP) or block‐on‐ring (BOR) tribotests. Comparative tests for pure, oil‐filled and solid lubricated polymers at 100N and 0.3m/s are presented for relative material classification. Differences are discussed according to the sliding geometries. Thermal effects dominate friction and wear behaviour: the polymer glass transition temperature is exceeded in COP tests while the temperature is lower in BOR tests. Thick and brittle films are observed for pure polymers in BOR tests, promoting higher friction. The test configuration is mainly important for evaluation of internal lubricants. The efficiency of oil‐lubricated polymers is not demonstrated in COP tests, while solid lubricants are not efficient in BOR tests. Deformation restricts the diffusion of oil lubricants in COP tests while solid lubricants are deposited on the polymer surface rather than being incorporated in the transfer film in BOR tests. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
9.
The tribological behaviour of oil‐lubricated steel‐alumina sliding pairs was investigated using a ball‐on‐disc tribometer at room temperature. Commercial bearing balls of 10 mm diameter were mated to 99.7% Al2O3 discs, and additive‐free mineral oil was fed into the contact area. The sliding speed and the applied normal load were varied, and the initial surface roughness of the Al2O3 disc was altered using different polishing and grinding procedures. The results showed that the surface roughness of the ceramic discs dominated the tribological behaviour under the given experimental conditions. The sliding speed as well as the normal load showed less effect on the friction behaviour, but the amount of wear depended strongly on the normal load. From the results it was concluded that improvement of the surface roughness and optimised surface machining of the ceramic material can be essential for improving the tribological performance for boundary‐lubricated steel‐ceramic sliding pairs. 相似文献
10.
Wear modeling is essential to predict and improve wear resistance of machine parts. This article presents a fatigue wear model of plane sliding pairs under dry friction. The wear model is constructed through developing a dynamic contact model of surfaces and proposing a mean fatigue damage constant of asperities. It is simpler and more practical than existing fatigue wear models because it describes the quantitative relationship between the wear behaviors of the plane sliding pairs and the main factors including the load and sliding speed, material property, friction property, and surface topography of the pairs. Furthermore, the wear model can predict the wear of each component of the sliding pairs. Reasonability and applicability of the wear model are validated via pin-on-disc wear tests. The wear model is applicable to predict the wear of the plane sliding pairs, which is characterized by friction fatigue of contact surfaces. The wear model can also be used to guide the tribological design of sliding pairs in machinery. 相似文献
11.
Comparison of the wear behaviour of six bearing materials for a heavily loaded sliding system in seawater 总被引:1,自引:0,他引:1
P. De Baets 《Wear》1995,180(1-2):61-72
A problem of severe wear occurred at the guidance system of a door of a sea-lock. The seawater immersed guidance was a linear system with aluminium bronze bearing material on stainless steel rail material. A satisfactory laboratory simulation of the wear behaviour of the guidance system was achieved by testing with large test specimens. Six bearing materials were tested. Nodular and lamellar cast iron suffered severe scuffing and cannot be used. Sintered graphite bronze shows a wear coefficient about six times smaller than the original aluminium bronze. Two plastics were tested: PETP and PA. PA has the best friction and wear characteristics and is suggested as bearing material for the sliding system. 相似文献
12.
The friction and wear of short glass fiber reinforced polyamide 12 (PA12) were investigated. The behavior of the fibers on a sliding surface and their effect on the friction and wear were studied in terms of the amount and orientation of the fibers in the composite. Results showed that the friction level and wear resistance were strongly affected by the fiber content, and glass fiber patches produced on the sliding surface played important roles in the wear resistance of the composite. The optimum fiber content for the best wear resistance of the PA12 composite was approximately 30 wt.% and higher fiber contents had no added effect on the wear amount. The applied load also strongly affected the wear resistance due to the increase in temperature at the sliding interface, and an increase in rapid wear was observed when the interface temperature increased above the glass transition temperature of PA12. On the other hand, the fiber orientation had less effect on the friction and wear of the composite compared to the fiber content and applied load. Based on the behavior of glass fibers on the sliding surface and wear debris analysis, the wear mechanism of the PA12 composite is discussed. 相似文献
13.
In this investigation, the influence of test speed and applied pressure values on the friction and wear behaviour of polyamide 66 (PA 66), polyoxymethylene (POM), ultrahigh molecular weight polyethylene (UHMWPE), 30% glass fibre reinforced polyphenylene-sulfide (PPS+30%GFR) and aliphatic polyketone (APK) polymers were studied. Friction and wear tests of PA 66, POM, UHMWPE, PPS+30%GFR and APK versus AISI D2 steel were carried out at dry condition on a pin-on-disc arrangement. Tribological tests were performed at room temperature at different pressures (0.35–1.05 MPa) and sliding speeds (0.5–2.0 m/s). The results showed that, for all polymers used in this investigation, the coefficient of friction decreases linearly with the increase in pressure. The specific wear rate for UHMWPE, PPS+30%GFR and APK were in the order of 10−5 mm3/N m, while the wear rate value for PA 66 was in the order of 10−6 mm3/N m. In addition to this, the wear rate value for POM was in the order of 10−3 mm3/N m. Furthermore, as the results of this investigation, the wear rate showed very little sensitivity to the applied pressures and test speed. 相似文献
14.
Zsidai L. Samyn P. Vercammen K. Van Acker K. Kozma M. Kalácska G. De Baets P. 《Tribology Letters》2004,17(2):269-288
Polymers are increasingly used in tribological applications, because of their self-lubricating ability, corrosion resistance and chemical compatibility. However, their performance depends strongly on the parameters of the total tribological system. Not only polymer characteristics, but also counterface properties become important because of their influence on friction and wear, on surface energy and on the thermal conductivity of the total system. Applying a Diamond-Like Nanocomposite (DLN) coating on a steel counterface can improve the tribological behaviour of the sliding couple under certain conditions. In the case of metal sliding against DLN, the high hardness and the wear resistance of the coating is advantageous for better tribological properties. However, for polymers sliding against DLN, the lower thermal conductivity of the DLN coating compared with a steel mating surface dominates friction and wear. In case of polyamides this results in worse tribological performance in contact with the DLN coating, because of polymer melting. In the case of more rigid polymers, such as, e.g., POM-H and PETP, lower coefficients of friction lead to lower frictional heat generation. In these cases, the thermal characteristics of the counterface are less important and the lower surface energy of the DLN coating is favourable for decreased adhesion between the polymer and the coating and consequently better tribological properties. 相似文献
15.
《Wear》2006,260(1-2):109-115
Dry-sliding and lubricated friction and wear behaviours of polyamide (PA) and ultra-high molecular weight polyethylene (UHMWPE) blend were studied using a pin-on-disc method (polymer pin sliding against a stainless steel disc) at room environment. The tribological performance of PA and UHMWPE were also investigated for the purpose of comparison. The worn surfaces were examined using a scanning electron microscope (SEM) and optical microscope. It was observed that PA specimen demonstrated highest friction coefficient, UHMWPE the lowest in both dry-sliding and lubricated sliding test. The friction of PA could be sufficiently decreased by blending with UHMWPE. Statistical analysis suggested the relationship between the wear volume loss and the sliding distance could be expressed by a linear model for dry-sliding, while a logarithmic model was determined for lubricated sliding. The difference in wear modes between both sliding series suggested that there was change in the mode of material removal process. The lower wear rate in lubricated sliding was attributed to the elastohydrodynamic or partial elastohydrodynamic lubrication through the development of a continuous lubricant film between the polymer and the counterface, while the high wear rate of the specimens, in dry-sliding test, was mainly caused by fatigue process due to the repeated action of tearing and crack-propagation. 相似文献
16.
The sliding friction and wear behaviours of Ti–6Al–4V alloy were investigated under dry sliding wear conditions. The wear tests were carried out on a pin-disc tribometer at sliding speeds from 30 m/s to 70 m/s and at contact pressure ranging from 0.33 MPa to 1.33 MPa. Pins of the Ti–6Al–4V alloy are used in both solution treated and aged conditions. The objective of the study is to understand the influence of thermo-mechanical mixed layers (TMML), which form on the surface of the worn material during the course of the wear test, on the friction and wear behaviour. Detailed characterization of the TMML was carried out using SEM, EDS and micro-hardness testing in order to understand the influence of test velocity and contact pressure on the composition, hardness and thickness of the TMML formed. The influence of the TMML on the friction and wear behaviour was also studied. On the basis of the above characterization, it was demonstrated that the observed friction and wear behaviour of Ti–6Al–4V alloy can be best understood in terms of the formation and fracture rate of the TMML rather than the bulk properties of the material. 相似文献
17.
An onion-like carbon material was prepared from candle soot, and its tribological properties as an additive were investigated in water. The material assumed a spherical shape with a layered nanostructure based on high-resolution transmission electron microscopic analysis and had considerable sp2 hybrid carbon as revealed by Raman spectroscopy. The tribological properties were determined on an optimal SRV-IV oscillating reciprocating friction and wear tester. The results indicate that these candle soots as additives are able to effectively reduce both the friction and wear of sliding pairs in water. In addition, the chemical reactivity, physical stability, surface charge, and size of candle soot had a key impact on their lubrication properties. Based on our characterization of the wear scars by scanning electron microscopy and in situ Raman spectroscopy, we suggest a rolling and sliding lubrication mechanism. 相似文献
18.
《Tribology - Materials, Surfaces & Interfaces》2013,7(4):155-159
AbstractAn attempt on modification of tribological behaviour of cotton polyester composite was done with polytetrafluoroethylene (PTFE). PTFE modified polyester–cotton composites were developed and studied for their friction and sliding wear behaviour at different applied loads. The sliding wear tests of composites were conducted against EN-31 steel counter face. The coefficient of friction μ as well as the sliding wear rate of cotton–polyester composites reduced significantly on addition of PTFE. The reduction in wear rate of PTFE modified polyester–cotton composite has been discussed with the help of SEM observations of worn surfaces and coefficient of friction. 相似文献
19.
The friction and wear of monolithic polyamide 66 (PA66) and a PA66 composite reinforced with short glass fibers were examined
using a block-on-ring friction tester with particular focus on the effect of weight average molar mass (M
w) of PA66. The amount of glass fibers in the composite and the molecular weight strongly affected the friction level and wear
rate because it altered the shear strength and adhesion of PA66. In the case of the glass fiber-reinforced PA66 composites,
the improvement of the tribological property was attributed to the increased softening temperature of the composite and reduced
material transfer to the counter surface. From this study, the optimum composite having the improved wear resistance with
the low friction level was achieved with the lower M
w PA66 containing 40 vol.% glass fibers. 相似文献
20.
Investigations on the influence of graphite filler on dry sliding wear and abrasive wear behaviour of carbon fabric reinforced epoxy composites 总被引:1,自引:0,他引:1
In this experimental study, the dry sliding wear and two-body abrasive wear behaviour of graphite filled carbon fabric reinforced epoxy composites were investigated. Carbon fabric reinforced epoxy composite was used as a reference material. Sliding wear experiments were conducted using a pin-on-disc wear tester under dry contact condition. Mass loss was determined as a function of sliding velocity for loads of 25, 50, 75, and 100 N at a constant sliding distance of 6000 m. Two-body abrasive wear experiments were performed under multi-pass condition using silicon carbide (SiC) of 150 and 320 grit abrasive papers. The effects of abrading distance and different loads have been studied. Abrasive wear volume and specific wear rate as a function of applied normal load and abrading distance were also determined.The results show that in dry sliding wear situations, for increased load and sliding velocity, higher wear loss was recorded. The excellent wear characteristics were obtained with carbon-epoxy containing graphite as filler. Especially, 10 wt.% of graphite in carbon-epoxy gave a low wear rate. A graphite surface film formed on the counterface was confirmed to be effective in improving the wear characteristics of graphite filled carbon-epoxy composites. In case of two-body abrasive wear, the wear volume increases with increasing load/abrading distance. Experimental results showed the type of counterface (hardened steel disc and SiC paper) material greatly influences the wear behaviour of the composites. Wear mechanisms of the composites were investigated using scanning electron microscopy. Wear of carbon-epoxy composite was found to be mainly due to a microcracking and fiber fracture mechanisms. It was found that the microcracking mechanism had been caused by progressive surface damage. Further, it was also noticed that carbon-epoxy composite wear is reduced to a greater extent by addition of the graphite filler, in which wear was dominated by microplowing/microcutting mechanisms instead of microcracking. 相似文献