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991.
Tribological performance of molecular thermoplastic elastomeric films grafted onto a silicon surface was enhanced by adding a minute amount of paraffinic oil, which was adsorbed by the rubber matrix. The nanocomposite films show bimodal distribution of the surface elastic modulus, caused by the nanodomain structure. Minute amounts of oil, trapped within the rubber phase after evaporation, modified the nanotribological properties of these layers. We observed a significant decrease of the friction coefficient by 40%, along with a lower elastic modulus of the rubber phase. We suggest that under high shear stresses and sliding velocity, oil molecules can be compressed out of the bulk to the surface, facilitating instant local lubrication of the contact area. 相似文献
992.
A friction-seizure test procedure is proposed to analyze phosphate/stearate coating performance in relation to stressing conditions. Test results, including the occurrence of hydrodynamic lubrication, mixed lubrication and seizure at the slider/specimen coated interface, are related to effective phosphate bonding and to lubricant reactive effects. The soap settling process is analyzed in terms of seizure sensitiveness and coating aging is studied in relation to moisture content and temperature. The effects of coating surface temperature on the occurrence of lubrication type and seizure are also analyzed for reactive and unreactive soaps. Stressing conditions such as sliding velocity and contact pressure are studied and a coating behaviour law for seizure is finally proposed. 相似文献
993.
The effect of counterface surface roughness on the wear of UHMWPE in water and oil-in-water emulsion
The South African gold mining industry is at present involved in a programme whereby the hydraulic stoping machinery currently operating on a water-based fluid will be modified to run on mine service water. The wear of the UHMWPE seals is an area of particular concern. This paper examines the effect of type of lubricant and counterface surface roughness on the wear of UHMWPE. A reciprocating sliding wear rig was used with UHMWPE sliding against AISI 431 at an average speed of 0.25 m/s. The contact pressure was 10 N/mm2. Tests were conducted in water and in a 5% oil-in water emulsion (5:95). The surface roughness of the steel was varied in the range 0.1–1.0 μm (centreline average). The results of the tests in water showed that the logarithm of the specific wear rate is proportional to the surface roughness. The results of the tests in 5:95 showed that there is a significant transition in specific wear rate at a surface roughness of approximately 0.35 μm. At surface roughness less than 0.35 μm the specific wear rate in 5:95 is considerably lower than the specific wear rate in water, while at surface roughness greater than 0.35 μm the specific wear rate in 5:95 approaches that in water. However, SEM examination of the surfaces from both series of tests showed that, irrespective of lubricant, there was a change in the mode of material removal at a surface roughness of approximately 0.35 μm. The wear mechanisms are discussed as a function of type of lubricant and surface roughness. It is believed that the topography of the counterface is responsible for the change in the mode of material removal. 相似文献
994.
The tribological behavior of alumina (Al2O3) in CF3CH2F (HFC-134a) gas at pressures between 170 Pa and 105 Pa were investigated using a ball-on-disk type tribometer. For comparison, the friction test was also carried out in a vacuum (10−5 Pa) under the same experimental conditions. X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ions Mass Spectrometry (TOF-SIMS) were used to identify the formation of tribochemical products.It was found that the friction and wear properties of Al2O3 were strongly dependent on the pressure of HFC-134a gas. A higher pressure correlated to a lower friction coefficient. When the pressure exceeded 103 Pa, the wear strikingly decreased. The results of XPS and TOF-SIMS analyses identified that tribochemical films, mainly composed of fluorine-containing organic compounds and Al-oxyfluorides, were produced on the frictional surfaces. In addition, it was found that the amount of the fluorides correlated well to the friction and wear properties, that is, the more the fluorides were, the lower were the friction and wear. The results of research indicate that HFC-134a gas has a good lubricating effect for Al2O3 ceramic, which is attributed to the formation of the tribofilms at the frictional interface. 相似文献
995.
This paper describes the tribological impacts of hydrocarbon refrigerants deployed in the domestic refrigerator hermetic compressor. In-use durability is examined from a tribological viewpoint. Experimental tribological information is presented from physical test procedures involving sliding tests to establish wear mechanisms and friction coefficients within critical components. Hydrocarbon refrigerant R600a is compared with hydroflourocarbon R134a using aluminium on steel samples within a novel pressurised micro-friction test rig. The refrigerant R600a is tested for its influence upon the tribological performance of mineral oil (MO) and poly-ol-ester (POE) lubricant, whilst an R134a/POE charge combination is used as a benchmark. Although wear rates were significantly greater for samples utilising POE lubricants than for MO, the friction coefficients were much lower. 相似文献
996.
Although earlier investigations on the tribological behaviour of amcrphous hydrogenated carbon (AHC) films in sliding contact with steel showed encouraging results, four open issues were identified. They were: (a) dependence of friction and wear on humidity (i.e., the friction coefficient and the wear increased with humidity), (b) limitations on film thickness (i.e., films greater than 2 μm thick delaminated due to large compressive stress), (c) deposition of films on substrates other than silicon and (d) lubricant compatibility (i.e., formation of lubricant-derived antiwear films on AHC film surfaces). Steps were taken to address some of these open issues by incorporating silicon in AHC films. Friction and wear tests were conducted on AHC films containing various amounts of silicon. Incorporation of silicon in AHC films rendered the friction coefficients and the wear of a steel counterface insensitive to moisture. Silicon incorporation in AHC films also significantly reduced compressive stress. This allowed deposition of 10 μm thick films. These effects were achieved without any compromise with the friction coefficient and the film wear if the amount of silicon in the film was kept within a certain concentration range. In addition, silicon-containing AHC films were thermally more stable than silicon-free films. Experiments conducted with two lubricants resulted in significantly lower wear of the silicon-free AHC films than that obtained for unlubricated sliding. Similar friction coefficients were obtained for AHC film/steel and steel/steel combinations in lubricated sliding. 相似文献
997.
998.
999.
A ball-on-flat reciprocating micro-tribometer has been used to measure the friction coefficient between aluminium alloy strip and a steel ball. A relatively small ball and correspondingly low contact load is used to give a contact width of the order of 100 m, closer to asperity contact widths than generally found for this type of test. The effects of load, initial strip surface roughness, lubricants and boundary additives are investigated. It is found that the friction coefficient is significantly reduced by the addition of a lubricant. Observations of the wear tracks and ball surface show that the material transfer from aluminium to the ball is reduced in the presence of the lubricant. The initial friction coefficient is further reduced by the addition of a boundary additive, but the friction coefficient after 8 cycles is unchanged. 相似文献
1000.
Effect of tetraalkylphosphonium based ionic liquids as lubricants on the tribological performance of a steel-on-steel system 总被引:2,自引:0,他引:2
A series of asymmetrical tetraalkylphosphonium ionic liquids were synthesized and evaluated as a new kind of lubricant for
the contact of steel/steel using an Optimol SRV oscillating friction and wear tester in ambient condition. The phosphonium
ionic liquid shows excellent tribological performance when being used as the lubricating oil, and is superior to the conventional
high temperature lubricants X-1P and perfluoropolyether (PFPE) in terms of anti-wear performance and load-carrying capacity.
The chemical compositions of the boundary film generated on different contact surfaces were analyzed on a scanning electron
microscope with a Kevex energy dispersive X-ray analyzer attachment (SEM/EDS) and X-ray photoelectron spectrometer (XPS).
The friction–reduction and anti-wear mechanism of tetraalkylphosphonium as the lubricant were proposed to originate from the
active elements P in the tetraalkylphosphonium ionic liquids reacting with the fresh surface to form a reaction film onto
specimen surface, an extreme-pressure film with lower shearing strength, which leads to lower friction coefficient, and good
wear resistance. 相似文献