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1.
The wear and sliding friction response of a hybrid copper metal matrix composite reinforced with 10 wt% of tin (Sn) and soft solid lubricant (1, 5, and 7 wt% of MoS2) fabricated by a powder metallurgy route was investigated. The influence of the percentages of reinforcement, load, sliding speed, and sliding distance on both the wear and friction coefficient were studied. The wear test with an experimental plan of six loads (5–30 N) and five sliding speeds (0.5–2.5 m/s) was conducted on a pin-on-disc machine to record loss in mass due to wear for two total sliding distances of 1,000 and 2,000 m. The results showed that the specific wear rate of the composites increased at room temperature with sliding distance and decreased with load. The wear resistance of the hybrid composite containing 7 wt% MoS2 was superior to that of the other composites. It was also observed that the specific wear rates of the composites decreased with the addition of MoS2. The 7 wt% MoS2 composites exhibited a very low coefficient of friction of 0.35. The hardness of the composite increased as the weight percentage of MoS2 increased. The wear and friction coefficient were mainly influenced by both the percentage of reinforcement and the load applied. Wear morphology was also studied using scanning electron microscopy and energy-dispersive X-ray analysis.  相似文献   

2.
MoS2 coatings exhibit low coefficient of friction (COF) when sliding against aluminum; however, the magnitudes of their COF show high sensitivity to environmental conditions. Ti could reduce the sensitivity of the frictional behavior of MoS2 coatings to moisture. This study examines the tribological properties of Ti containing MoS2 coating (Ti–MoS2) tested against an aluminum alloy (Al-6.5% Si) in ambient air (58% relative humidity, RH), dry oxygen, dry air and dry N2 (< 4% RH) atmospheres. The Ti–MoS2 coating exhibited similar COF values under an ambient (0.14), dry oxygen (0.15) and dry air (0.16) atmospheres. It was found that oxidation of MoS2 to MoO3 was responsible for high COF under these testing conditions as revealed by Energy-dispersive X-ray Spectroscopy (EDS) and micro-Raman spectroscopy. However, a low and stable COF of 0.07 was observed under a dry N2 condition. This work further showed that the tests performed at elevated temperatures, up to 400 °C in a dry N2 atmosphere sustained the low and stable COF of the Ti–MoS2 coatings. The sliding tests performed under a dry N2 atmosphere prevented the formation of MoO3 and as a result, the Ti–MoS2 coatings maintained low COF values. Low COF values were also attributed to the formation of MoS2 transfer layers.  相似文献   

3.
Silver-based composite with 15?vol% MoS2 and with 5?vol% graphite was prepared by powder metallurgy method. The impacts of the counterface materials, atmosphere, and temperature on the tribological behavior of the composite were investigated. It was found that when sliding against brass less effective lubricating film formed, causing a higher friction and wear comparing with ASTM-1045 steel. With the increasing proportion of oxygen in the O2/N2 atmosphere, the wear rate and friction coefficient ascended slightly. At 200?°C, the combination lubrication of graphite, MoS2, and Ag contributed to a low friction coefficient (0.07) and wear rate (6.56?×?10?6?mm3/Nm). At 400?°C, graphite lost its lubricating role, while silver became excessively soft. Large amount of MoS2 was oxidized into MoO3, and the residual MoS2 formed some island-like lubricating films. Severe adhesive wear occurred on the contact surface, which led to a high friction coefficient (0.25) and a great increase of the wear rate (23.2?×?10?6?mm3/Nm). At 600?°C, a relatively low friction coefficient (0.1) was obtained because of the formation of high-temperature solid lubricants, (Ag2Mo4O13 and Ag2Mo2O7) and liquid Ag2Mo2O7. However, the wear rate at 600?°C was the highest (32.6?×?10?6?mm3/Nm) due to the thick transfer layer.  相似文献   

4.
The effects of applying a bonded MoS2 solid lubricant to a 1050 steel substrate were investigated using a torsional fretting wear apparatus. Tests were conducted under a normal load of 50 N with angular displacement amplitudes ranging from 0.1 to 5°. Wear scars were examined using scanning electron microscopy, energy-dispersive X-ray spectrometry, optical microscopy, and surface profilometry. The MoS2 coating exhibited different torsional fretting regimes than those of the substrate. Fretting regimes of the coating were primarily in the partial slip regime (PSR) and the slip regime (SR) with no mixed fretting regime. The width of the PSR narrowed. Due to the lubricating effects of the coating, the friction torque was consistently lower than that of the substrate. The damage to the coating in the PSR was very slight, and its granular structure remained even after 1,000 cycles. The damage mechanism to the SR coating was a combination of abrasive wear, oxidative wear, and delamination. The MoS2 coating had potential to alleviate torsional fretting wear.  相似文献   

5.
Tribological behaviors and the relevant mechanism of a highly pure polycrystalline bulk Ti3AlC2 sliding dryly against a low carbon steel disk were investigated. The tribological tests were carried out using a block-on-disk type high-speed friction tester, at the sliding speeds of 20–60 m/s under a normal pressure of 0.8 MPa. The results showed that the friction coefficient is as low as 0.1∼0.14 and the wear rate of Ti3AlC2 is only (2.3–2.5) × 10−6 mm3/Nm in the sliding speed range of 20–60 m/s. Such unusual friction and wear properties were confirmed to be dependant dominantly upon the presence of a frictional oxide film consisting of amorphous Ti, Al, and Fe oxides on the friction surfaces. The oxide film is in a fused state during the sliding friction at a fused temperature of 238–324 °C, so it takes a significant self-lubricating effect.  相似文献   

6.
MoS2–Cr coatings with different Cr contents have been deposited on high speed steel substrates by closed field unbalanced magnetron (CFUBM) sputtering. The tribological properties of the coatings have been tested against different counterbodies under dry conditions using an oscillating friction and wear tester. The coating microstructures, mechanical properties and wear resistance vary according to the Cr metal-content. MoS2 tribological properties are improved with a Cr metal dopant in the MoS2 matrix. The optimum Cr content varies with different counterbodies. Showing especially good tribological properties were MoS2–Cr8% coating sliding against either AISI 1045 steel or AA 6061 aluminum alloy, and MoS2–Cr5% coating sliding against bronze. Enhanced tribological behavior included low wear depth on coating, low wear width on counterbody, low friction coefficients and long durability.  相似文献   

7.
Roll/slide friction tests were carried out at a temperature of 750°C in a vacuum. Disc specimens were made of Si3N4 with or without a sputtered MoS2 film. A pin specimen was rubbed against one disc to supply a lubricating transfer film. With a pin made of an MoS2‐based composite, the friction coefficient was around 0.3 and almost no wear of the discs was observed after 24 h of operation at a load of 50 N, a rotating speed of 0.5 m/s, and a slip ratio of 10%. Transferred patchy MoS2 films were observed on the friction track. With a pin made of Ni‐based composite containing BN and graphite, the friction coefficient increased from 0.2 to 0.7 over a test time of about 8 h and severe disc wear was found. In an additional test using Si3N4 discs with a sputtered MoS2 film without a pin, the friction coefficient was about 0.3, and no wear of the discs was found after 24 h of operation. The appearance of the friction track was similar to that in the test using the MoS2‐based composite pin. It seems that the sputtered MoS2 film wore, but wear particles reattached on the friction path to develop an effective lubricating film. These results demonstrate the effectiveness of transfer film lubrication for long‐term operation in a high‐temperature vacuum, and the superior ability of MoS2 to develop an effective transfer film.  相似文献   

8.
The wear and frictional behaviour of compressed pellets of molybdenum disulphide (MoS2) were measured when the pellets were slid against a 0.45% C steel disk in air. The wear of the MoS2 pellets decreased with increasing sliding velocity and increasing contact pressure. These factors are indicated by a parameter μPV which corresponds to the frictional heat. A thin deformed surface layer on the sliding surface of an MoS2 pellet was different from the MoS2 substrate.The wear of a bearing steel slider against mild steel was reduced by an MoS2 film in air and in vacuum. The specific wear rate of the slider and the coefficient of friction were influenced by the degree of vacuum.  相似文献   

9.
More durable, low-friction self-lubricating materials in modern industry are greatly needed for tribological systems. The current paper presents the tribological performance of TiAl matrix self-lubricating composites (TSC) containing MoS2, hexagonal BN and Ti3SiC2 designated as MhT against GCr15 steel counterface under several sliding speeds from 0.2 to 0.8 m s?1 and applied loads from 6 to 12 N. The results suggested that MhT played an important role in decreasing friction coefficients and wear rates. The covering percentage of transfer layers on worn surfaces varied with the changing of sliding speeds and applied loads, hence resulting in the distinct friction and wear characteristics of TSC. TSC containing 10 wt% MhT exhibited the best excellent tribological performance at 10 N–0.8 m s?1, which could be due to the formation of the best compaction and largest coverage of transfer layer on the worn surfaces.  相似文献   

10.
Nano-objects in dry and liquid conditions have shown reductions in friction and wear on the macroscale. Studies in low viscosity liquids with nanoparticles and nanotubes made of lubricating materials such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are limited. In this research, MoS2 and WS2 nanotubes with spherical gold (Au) nano-objects as a control are studied on the nanoscale under dry and low viscosity liquid environments for their effect on friction and wear reduction. Atomic forces microscopy (AFM) experiments on the nanoscale are performed in single-nano-object contact with an AFM tip, where nano-objects are laterally manipulated and multiple nano-object contact with a tip attached to a glass sphere sliding over several nano-objects. Wear tests were performed on the nanoscale by means of AFM as well as on the macroscale using a ball-on-flat tribometer to relate friction and wear reduction on both scales. Results indicate that nano-objects such as MoS2 and WS2 nanotubes contribute to friction and wear reduction due to the reduced contact area and the possible rolling and sliding on the nanoscale. On the macroscale, reductions in friction and wear occur due to possible exfoliation of outer layers in addition to other mechanisms just mentioned.  相似文献   

11.
More durable, low-friction bearing materials over a wide temperature range are needed for turbine components and other high-temperature bearing applications. The current study reported the tribological properties of TiAl matrix self-lubricating composites (TMC) containing MoS2 (a low-temperature lubricant, below 500°C), hBN (a medium-temperature lubricant, below 600°C), and Ti3SiC2 (a high-temperature lubricant, above 600°C) designated as MhT against an Si3N4 counterface at temperatures ranging from 25 to 800°C in air. The load was 10 N and the sliding speed was 0.2 m/s for all tests. Tribological studies indicated that TMC containing MhT showed a lower friction coefficient and wear rate in comparison to TiAl-based alloy at all test temperatures, which was attributed to the excellent synergetic lubricating effect of MoS2, hBN, and Ti3SiC2. TMC containing 5 wt% MhT exhibited the best tribological properties over a wide temperature range.  相似文献   

12.
Synthesis and tribological evaluation of three tetraalkylammonium thiomolybdate (R4N)2MoS4 (R = methyl, propyl, or ammonia) aqueous-based lubricant additives on a ball-on-disk tribometer was carried out for a steel–aluminum contact. Tests were performed at the same conditions of load, entrainment speed, sliding distance, temperature, and concentration of MoS2 to compare the activity (lubrication effect) of the thiomolybdates prepared. A friction reduction is observed for the three salts compared to pure water; however, significant differences in friction coefficient are observed depending on the alkyl group. SEM/EDAX and Raman analysis of the wear tracks reveal the in-contact formation of a MoS2-lubricating film, rich in molybdenum and sulfur.  相似文献   

13.
Ocean tribology, a new research field of tribology, is currently being established and developed. The tribological behaviors of polyether ether ketone (PEEK), poly(phenyl p-hydroxybenzoate) (PHBA), polyimide (PI), and perfluoroethylene propylene copolymer (FEP) sliding against GCr15 and 316 steel rings under the lubrication of sea water were studied and compared with that under the lubrication of pure water. The results show that the friction and wear behaviors of a polymer under the lubrication of aqueous medium are not only related to the properties of polymer itself, but also to the corrosive effect and lubricating effect of the medium. When a polymer slid against GCr15 steel under sea water lubrication, the friction coefficient and wear rate of polymer were much larger than that under pure water lubrication because of indirect corrosive wear. However, when sliding against corrosion-resistant 316 steel, polymers PEEK, FEP, and PI exhibited lower coefficients of friction and wear rates under sea water lubrication, this was attributed to better lubricating effect of sea water as a result of the deposition of CaCO3 and Mg(OH)2 on the counterface. On the contrary, the friction coefficient and wear rate of PHBA sliding against 316 steel under sea water lubrication were larger than that under pure water lubrication, which may be related to the properties of PHBA itself.  相似文献   

14.
M. Matsui  H. Kakishima 《Wear》2006,260(6):669-673
The effect of shot-peening treatment with the particulate MoS2 solid lubricant on the wear resistance of steel in the dry rolling/sliding contact wear tests was investigated. The duplex shot-peening treatment with ceramic balls and the particulate MoS2 solid lubricant provided excellent wear resistance under a severe loading and sliding condition because the uniform and minute surface roughness given by shot-peening treatment with ceramic balls could keep shot-peened MoS2 particles with a low friction coefficient on the sample surface. Furthermore, the sample surface was covered with shot-peened MoS2 particles by a MoS2 layer formed during the rolling/sliding contact wear test.  相似文献   

15.
In this present work, the in situ Al (A380)/5 wt%TiB2 composites were fabricated through salt–melt reaction using halide salts such as potassium hexafluorotitanate (K2TiF6) and potassium tetra fluoroborate (KBF4) salts as precursors. The composites were produced at four different melt temperatures (700, 750, 800, 850 °C). The formation of particle was confirmed from XRD results. The wear behaviour of Al/5 wt% TiB2 composite was investigated by varying the wear test parameters such as sliding temperature (25, 100, 150, 200 °C), applied load (10, 20, 30, 40 N), sliding velocity (0.4, 0.7, 1, 1.3 m/s). The microstructure of Al/5 wt% TiB2 composite was correlated with the wear characteristics of the composites. The wear resistance of Al/5 wt% TiB2 composite was significantly improved due to the presence of TiB2 particle in Al matrix material. The composite produced at melt temperature 800 °C showed a higher wear resistance at applied load: 10 N, sliding temperature: 25 °C and sliding velocity: 0.7 m/s. The wear mechanism for each of the tested condition was identified from the worn surfaces using scanning electron microscopy (SEM). ANOVA test was carried out to find out significant factor for the wear resistance of composite. The checking of adequacy of experimental value for the wear behaviour of composite for different testing condition was analysed by residual plots using statistical software.  相似文献   

16.
Self-lubricating polymer–steel laminated composites (SLC) consisting of matrix zones and filled zones were fabricated by a laminating–bonding process. The matrix zones were silicon steel sheets and the filled zones were polymer matrix filled with MoS2 and graphite, respectively. The control specimen was prepared by spraying a polymer composite coating on a GCr15 disc. The tribological properties of SLC were investigated using a ball-on-disc tribometer under different loads and frequencies. Compared to the control specimen, the friction coefficient and wear rate of SLC was reduced by 57% and threefold at 4 N and 6 Hz, respectively. In addition, the friction coefficient of SLC was low and stable under low reciprocating frequency, and it was high and fluctuating under high reciprocating frequency. In addition, the wear rate increased with increasing applied load and reciprocating frequency. Scanning electron microscopy (SEM) images show that the lubricating mechanism of SLC was that solid lubricants embedded in filled zones expanded and smeared a layer of transfer film on the sliding path to lubricate the surface. The thermal expansion of solid lubricants was simulated using ANSYS software with thermal-stress coupling. The simulation results showed the maximum temperature of the filled zones was 130°C, and the maximum normal displacement of solid lubricants was approximately 10 μm. This confirmed that the solid lubricants expanded effectively by the aid of frictional heat.  相似文献   

17.
Abstract

The tribological properties of soybean oil (SO) with different molybdenum disulfide (MoS2) additives (hollow nanosphere, nanoplatelet and microplatelet) were investigated. MoS2 hollow nanospheres remarkably improved the tribological properties of SO. SO with MoS2 hollow nanospheres decreased abrasive plowing and changed the main wear pattern on the steel friction surfaces into chemical corrosion. The MoS2 hollow nanospheres easily entered the contact region than the other MoS2 particles to lubricate the friction pair because of its good dispersibility in SO. The tribochemical reactions among MoS2 hollow nanospheres, SO and friction material produced a lubricating film composed of MoO3, Fe2O3, carbon containing compounds. Thus, the MoS2 hollow nanospheres have potential lubricating applications with SO. By contrast, MoS2 nanoplatelet and microplatelets had lesser effects on the lubricating effect of SO. The MoS2 nanoplatelets, even with its smaller size and more active chemical properties, had more difficulty in entering into the contact region because of its low dispersibility in the base oil.  相似文献   

18.
To explore the possibility of using advanced surface engineering techniques (ASETs) to solve the wear problems caused by the poor lubricity of pure, low-viscosity aviation fuel JP-10, polished M50 bearing steel sample surfaces were treated with nitrogen ion implantation, TiAlN coating deposition, and Ta coating deposition followed by high current pulsed electron beam (HCPEB) irradiation, respectively. Boundary tribological behaviors of these ASET-treated and untreated steel samples sliding in pure JP-10 against a Si3N4 ball (ball-on-disc model) were investigated under 2.0 GPa in the atmosphere and the friction tests indicated that significant, reductions, although to different extents, in friction and wear were achieved by these modified surfaces. Simultaneously considering the tribological performance and potential pollution caused by wear debris to JP-10, HCPEB-treated Ta coating with a lowest average friction coefficient of 0.11 and a specific wear rate of around zero was the fittest to offset the inadequate lubricity of JP-10 itself under the laboratory condition.  相似文献   

19.
Al2O3/Mo fibrous monolithic ceramics are potential candidates for space applications because of their excellent mechanical properties and low density. This study aims at achieving low friction and long life of this material in a high vacuum environment. Three-dimensional composite-lubricating layers were fabricated by considering texture pattern as storage dimples and MoS2 synthesized via hydrothermal method as lubricant. The tribological properties were studied sliding against Si3N4 ceramic and GCr15 bearing steel balls under high vacuum condition. Results showed that the lubricating properties of the Al2O3/Mo fibrous monolithic ceramics were improved greatly by the micro-texture and MoS2 solid lubricant; the friction coefficients were as low as approximately 0.08 and 0.04, respectively, when Si3N4 ceramic and GCr15 bearing steel balls acted as the pairing materials. It was also demonstrated that the low friction coefficient can be realized with various normal loads and sliding speeds, indicating the composite-lubricating layers have good adaptation of working conditions. This excellent performance of the material is mainly because of MoS2 stored in dimples can be easily dragged onto the friction surface to form lubricating and transferring films during the friction process. This work is an extension of studies that were previously published in Tribology Letters journal.  相似文献   

20.
TiAl matrix self-lubricating composites (TMC) with various weight percentages of Ti3SiC2 and MoS2 lubricants were prepared by spark plasma sintering (SPS). The dry sliding tribological behaviors of TMC against an Si3N4 ceramic ball at room temperature were investigated through the determination of friction coefficients and wear rates and the analysis of the morphologies and compositions of wear debris, worn surfaces of TMC, and the Si3N4 ceramic ball. The results indicated that TMC with 10 wt% (Ti3SiC2-MoS2) lubricants had good tribological properties due to the unique stratification subsurface microstructure of the worn surface. The friction coefficient was about 0.57, and the wear rate was 4.22 × 10?4 mm3 (Nm)?1. The main wear mechanisms of TMC with 10 wt% (Ti3SiC2-MoS2) lubricants were abrasive wear, oxidation wear, and delamination of the friction layer. However, the main wear mechanisms of TMC without Ti3SiC2 and MoS2 lubricants were abrasive wear and oxidation wear. The continuous friction layer was not formed on the worn surfaces. The self-lubricating friction layer on the frictional surface, different phase compositions and hardness, as well as density of TMC contributed to the change in the friction coefficient and wear rate.  相似文献   

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