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The aim of this study was to evaluate the tribological behavior of polyethylene crosslinked by gamma radiation sliding against a steel surface. Two high-density polyethylenes were irradiated to a total dose in the range of 2?20 Mrad under vacuum and at room temperature. After irradiation, the materials were annealed at 423 K and then cooled slowly to room temperature. The same thermal treatment was applied to the non-irradiated polymer. The wear behavior of the polymers was determined under controlled ambient temperature of 298 and 333 K using a homemade tribometer. Sheet-shaped specimens were loaded against the surface of a steel disc with different normal loads to generate nominal contact pressures in the range of 0.25–1.5 MPa. The tests were performed under dry conditions using a disc rotation to produce an average sliding speed of 0.6 m/s and during a period of time to provide an average sliding distance of 1,080 m. The wear rate was obtained as the mass loss by the sample divided by the sliding distance, and the friction coefficient was determined by measuring the friction force. The results indicate that the wear rate increases with load in the case of non-irradiated polyethylene and low-dose irradiated polymers, while the wear rate reaches a maximum value with the load in the case of the irradiated samples with high doses. The samples irradiated with a dose of 10 Mrad showed the lowest wear. The coefficient of friction (COF) increases slightly with the load in all the cases. Most irradiated polymers show higher COF than the non-irradiated material when compared at a given load. The results show that the irradiation dose applied to the polyethylenes produced no noticeable effect on the COF values when a comparison was made at a given applied load. 相似文献
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The effects of normal load and velocity on the friction and wear behavior of single-phase Fe2B bulk have been investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Results indicate that the friction coefficient and wear rate both decrease at first and then increase with increasing load and velocity, respectively. Attributed to the formation of a lamellar film on the Fe2B surface, the lowest friction coefficient and wear rate are obtained at a velocity of 0.2 m/s under a load of 12 N. The dynamic friction coefficients under loads of 4 and 12 N are around 0.8 in the initial steady stage and then decrease to about 0.6, whereas the friction coefficient at 20 N shows no obvious change and remains around 0.82. The lubricating film consisting of Fe2O3, B2O3, SiO2, and H3BO3 reduces the friction coefficient at 0.2 m/s under a load of 12 N. 相似文献
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MoSi2/45#钢在干摩擦条件下的滑动摩擦磨损性能 总被引:1,自引:0,他引:1
在MRH-5A型环-块型摩擦磨损实验机上,考察了MoSi2与调质45#钢配对时的摩擦磨损特性。运用KYKY2800型扫描电子显微镜,观察和分析了其磨损表面形貌,探讨了该材料的磨损机制。结果表明:在pv为284.96N.m.s^-1时,MoSi2与调质45#钢对摩时具有较低的摩擦因数和磨损率。在载荷和转速两影响因素中,转速的影响较大,低转速时MoSi2的磨损机制为粘着,且随着载荷的增加,出现粘着膜脱落;高转速时MoSi2材料表面粘着较低速时减弱。 相似文献
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Semi-interpenetrating network composites containing 40 vol.% ceramics (5Al2O3·8SiO2) and 60 vol.% Al-alloy were fabricated in place of cast iron available for automotive brake rotors. The friction and wear
performances of brake pads dry sliding against the composites were measured using a SRV testing machine. The test procedures
include friction fade and recovery, load sensitivity at 100 and 250°C, and wear. The friction was found to increase first
and then decrease with increasing temperature, followed by the inverse recovery upon cooling. Wear showed an incremental tendency
over a wide temperature range. For loads from 40 to 160 N, the friction decreased at 100 and 250°C. At load below 128 N, the
former friction was inferior to the latter while at load above 128 N the friction exhibited an inverse tendency. Wear mildly
increased with load at 100 °C and decreased dramatically at 250 °C. SEM and EDS investigations revealed that the worn pad
surfaces at 250 °C were covered by more tribofilms, including more coke and graphite with friction-reducing action as well
as fewer compounds (corresponding to Si and Al) with friction-increasing action in comparison with those at 100 °C. The compression
of the tribofilms contributed to a large decrease in the friction and wear with increasing load. However, at 100 °C E-glass
fibers exposed at the worn surfaces inhibited the excessive wear of the pad despite lack of more tribofilms. Their glossy
surfaces decreased the friction. The proposed friction models explain some friction and wear behaviour better. 相似文献
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粉末涂料固体润滑膜滚动/滑动复合干摩擦磨损特性研究 总被引:2,自引:1,他引:1
在M-2000磨损试验机上考察了经过一次处理和经两次处理的40Cr钢环表面喷涂3种粉末涂料型固体润滑膜(P型、H型、E型)试样,在线载荷为104N/m、相对滑动速度为0.042 m/s、干摩擦滚动/滑动复合磨损条件下的摩擦磨损性能,通过扫描电子显微镜(SEM)对试样磨损表面以及磨屑进行了显微观察。结果表明:底材经过一次处理(化学底膜处理)的复合固体润滑膜试样,P型和E型在磨损后期的摩擦因数分别稳定在0.38和0.32,而H型在0.40左右跳动;P型和H型的涂层磨损脱落期为60 m in左右,E型为120 m in左右;质量磨损从小到大顺序为P型相似文献
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Q. Luo 《Tribology Letters》2010,37(3):529-539
To investigate the origin of running-in friction in unlubricated sliding wear, a magnetron sputtered multilayer coating TiAlN/VN
was tested on a ball-on-disc tribometer for a series of sliding durations from 10 to 1000 cycles, followed by careful observation
of the obtained worn surfaces using an field-emission gun scanning electron microscope. Three steps of friction variation
were found: (1) prior to wear particle generation, low initial friction coefficient was around 0.2–0.25 purely attributed
to the asperity contact; (2) then it increased steeply to a range of 0.4–0.5 in the first 100 cycles following the generation,
breaking and agglomeration of wear particles, and in particular the scaling-up of fish-scale-like tribofilm; (3) eventually
it approached to a steady-state value around 0.5 when the friction was governed by the viscous shearing of the tribofilm.
It is concluded that, under unlubricated sliding wear, the friction behaviour of transition metal nitride hard coating is
dominated by the viscous shearing of tribofilm adhesively bonding to the parent nitride coating. 相似文献
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Nano-structured TiAlCrYN coatings, grown by unbalanced magnetron sputtering on various steel substrates, exhibited friction
coefficients 0.6–0.8 and wear coefficients 10−16–10−15 m3 N−1 m−1 in dry sliding wear tests. This article reports comprehensive worn surface analyses using SEM, TEM, EDX, EELS and Raman spectroscopy.
A ~80 nm thick tribofilm formed on the TiAlCrYN worn surface was found to have dense amorphous structure and homogeneous oxide
composition of Cr0.39Al0.19Ti0.20Y0.01O0.21. Viscous flow of the amorphous tribofilm was dominant in causing the high friction coefficient observed. The coatings showed
combined wear mechanisms of tribo-oxidation and nano-scale delamination. 相似文献
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利用环-盘式摩擦磨损试验机研究了铜碲硒铁合金的干摩擦磨损行为,分析了载荷和摩擦速度等参数对该合金摩擦磨损性能的影响,并用扫描电子显微镜对磨损形貌进行了观察.结果表明:铜碲硒铁合金的摩擦因数随载荷的增加变化不大,但随摩擦速度的增加而明显增大;合金的磨损率随载荷和摩擦速度的增加均增大;在轻载低速条件下,合金的磨损机制以犁削磨损和粘着磨损为主;在重载高速条件下,磨粒磨损和粘着磨损加剧. 相似文献
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In order to attain self-lubrication in a wide range of temperatures, Ni-based powder metallurgy (P/M) composites containing
different amounts (8–20 wt%) of Ag were prepared, and their friction and wear characteristics were investigated against AISI
52100 steel at temperatures of 25, 400, and 600 °C. One composite containing 12 wt% Ag and 4 wt% h-BN was also prepared and
tested under the same conditions to analyze the effect of addition of h-BN on the friction and wear behaviors. The composites
mainly consisted of Ni-based solid solution, free tungsten, Ag, and BN as revealed by XRD and EDS analyses. The friction coefficients
and wear rates were found to decrease with increasing temperature and amount of silver. The friction coefficients shown by
the composites containing relatively higher amounts of silver were in the range from 0.25 to 0.16 with temperature increasing
from RT to 600 °C. The wear rates of the Ag/h-BN-containing composites were approximately an order of magnitude lower than
those of the Base Alloy (having no solid lubricant) at all the temperatures. The addition of 4 wt% h-BN resulted in slightly
greater friction and wear in comparison to the composites containing only silver. 相似文献
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J. K. Lancaster 《摩擦学汇刊》2013,56(3):187-201
The friction and wear properties of various carbons and graphites have been measured during sliding against themselves in air. Many materials exhibit sudden and large increases in both friction and wear at a critical combination of load, speed, and temperature, and the effects are most pronounced for electrographites and natural graphites. The sliding conditions at the transition are associated with a critical temperature of the contacting asperities, and the magnitude of this temperature, approximately 150–185 C for graphitic materials, has been estimated both directly and by application of flash-temperature theory. The phenomena accompanying the transitions are very similar to those occurring during dusting of carbon brushes at high altitudes, and a similar explanation is invoked in terms of the adsorption of water vapor and oxygen. The critical combinations of loads and speeds required to initiate the transition are much more severe than those normally encountered during the operation of carbon brushes and bearings. 相似文献
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Investigations on the dry sliding wear behavior of tungsten carbide (WC)-reinforced iron matrix composites were carried out at room temperature. Three sets of samples (unreinforced iron, 4 wt% micrometer-size (~5–15 μm) WC-reinforced iron and 4 wt% nanosize (~30 nm) WC-reinforced iron were prepared using a powder metallurgy route to assess their friction and wear behaviors under two different loads. The relative dry sliding wear performances of the micrometer-size and nanosize WC-reinforced composites were compared with unreinforced matrix. An increase in microhardness of the order of 2.5 times was observed in the case of 4 wt% nanosize WC-reinforced iron matrix compared to the unreinforced iron matrix. The wear rate was 1.35 to 1.45 times lower in the case of nanocomposites compared to the unreinforced iron matrix (under different experimental conditions). The values of the coefficient of friction (COF) of composites were found to decrease with increase in load. Nanocomposites showed lower COF, surface roughness, and fractal dimension (D) values than micrometer-size WC-reinforced composites and the unreinforced iron matrix. 相似文献
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The present research focuses on dry sliding friction and wear behaviour of Nimonic 80A and Nimonic 90 against Nimonic 75 at high temperature up to 1023 K. The influence of temperature, sliding distance and normal load on friction and wear behaviour of Nimonic 80A and Nimonic 90 against Nimonic 75 was studied using pin (Nimonic 75)-on-disc (Nimonic 80A and Nimonic 90). Lower wear and lower friction of superalloys was observed at high temperatures, as compared to room temperature. Surface morphological and surface analytical studies of fresh and worn surfaces were carried out using optical microscopy, 3D profilometer, scanning electron microscope, energy-dispersive X-ray spectroscopy and Raman spectroscopy to understand the friction and wear behaviour. The mechanism of the formation of microscale glaze layer is also discussed. 相似文献
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以用SiC、Ti(CN)和ZrO2颗粒增韧的三种Al2O3基复合材料为研究对象,利用销盘式摩擦磨损试验机研究了它们的摩擦磨损性能,通过扫描电子显微镜对其磨损形貌进行了观察和分析.结果表明:在本试验条件下,Al2O3基复合材料的耐磨性能与添加剂的种类有关,其耐磨性能好坏顺序为Al2O3/Ti(CN)、Al2O3/SiC、Al2O3/ZrO2;Al2Os/SiC复合材料的磨损机理主要为疲劳磨损和脆性断裂,Al2O3/ZrO2和A12O3/Ti(CN)复合材料的磨损机理主要为磨粒磨损. 相似文献