Papers by Keyword: Friction and Wear

Abstract: As friction pair, ZCuPb20Sn5 and No.45 steel are most in use in gear motor under oil lubrication. In order to investigate the tribological characteristics of ZCuPb20Sn5 and No.45 steel under emulsion lubrication, the authers tested them on MMW-1 friction and wear tester with sample pin and thrust ring. The relationships between the friction coefficient and the load, the friction coefficient and the speed, the wear rate and the load, the wear rate and the speed were provided. The worn surface of ZCuPb20Sn5 were investigated by means of scanning electron microscope. The results showed that, alone with the raising of the load and the speed, the wear rate of ZCuPb20Sn5 increased, but the friction coefficient reduced.

Abstract: The friction and wear behaviors of three kinds of spherical plain bearings with PTFE fabric composite liners were investigated by a high oscillating frequency and heavy load tribo-tester. Dry sliding tests were carried out at different oscillating frequencies. With the help of SEM and EDS, the differences of worn surfaces of the three spherical bearings were investigated. The results indicate that the fiber woven with PTFE effects the friction and wear characteristics of bearing, the tribological properties of bearing with Kevlar/PTFE fiber woven liner is the best in the three kinds of bearing. The abrasive wear are appeared on the surface of wore liners of bearingⅠ,while bearingⅡappeared normal wear, bearing III showed serious adhesive wear and abrasive wear.

Abstract: Take electrolytic copper powder and SiC powder as the raw materials, apply powder injection moulding to prepare SiCp/Cu composite, while the test result shows that only Cu and SiC exist in the sintered composite, the SiC particles evenly distribute within the Cu substrate. The friction coefficient and the morphology and elemental composition of the worn composite surface are measured in the fiction and wear test. The result shows that the friction coefficient of composite increase in a more gentle pace with the prolonging of the sliding time; the adhesion and plastic deformation of the worn surface of the composite containing 10 vol.% SiCp is light, and there exists certain abrasive wear; while the worn surface of the composite containing 15 vol.% SiCp show obvious abrasive wear, and there exist dense mechanically mixed layer; in addition to the inherent elements of the composite of Cu, Si and C, the worn surface also contains the elements of Fe and O.

Abstract: In order to improve the wear resistance of drill tools, stellite190 welding coatings were prepared by oxygen-acetylene flame welding technology. The abrasive wear behavior and wear mechanisms of the coatings were investigated in both dry and water friction conditions. The research results show that the wear losses of the coatings increase with the increase of loads and sliding speeds. The effects of sliding speeds on wear losses of the coatings become intense with the increase of loads. The wear losses of the coatings in water friction condition are bigger than those in dry friction condition. The main wear mechanisms of the coatings are micro-cutting and multi-plastic deformation wear in dry friction condition, and accompanied by stress corrosive wear in water friction condition.

Abstract: In this paper, some Ag-carried palygorskite nanocomposites P/Ag were prepared, their silver content were 1.3%, 4.61%, 9.54% separately. To investigate the effects of the silver content on tribological properties of 45 mild steel pairs, the P/Ag carried different Ag content were used as lubricant additive and their tribological properties were tested on the MMU-10G testing machine. The wear mass loss is used to assess the anti-wear properties of different additives. The surface topographies and main elements are analyzed through SEM and EDS after running for 30 hours. The results show that the friction coefficient and the wear mass loss significantly decrease along with the increase of silver content in the P/Ag: the average friction coefficient of the P/Ag with 9.54% silver reduces about 65% as much as the one with 1.3% silver, meanwhile, the wear mass loss decreases 57% likewise. The surfaces after rubbing 30 hours, some kind of auto-restoration films that contains sort of characteristic elements such as O, Si, Mg, Al, Ag etc. are formed on the surfaces. With the help of this kind of films, the anti-wear properties of the friction pairs are finally improved. The factors that cause the improvement of anti-friction properties of the friction pairs lie in the quality and the silver content of the auto-restoration films formed on the surfaces of friction pairs.

Abstract: A kind of novel polytetrafluoroethylene (PTFE)-based composite filled with nano SiO₂ are developed for sliding tribological applications. The specimens are fabricated with the compression moulding technique. And the mechanical and tribological properties of the composites are investigated. It is demonstrated that these properties are influenced by the content of fillers. The wear resistances of all the developed PTFE composites are much higher than that of pure PTFE with very low coefficients of friction. Among the developed composites, the mixture of PTFE + 30% nano SiO₂ exhibits the best combination of properties. The improved tribological performance of nano-SiO₂ filled PTFE composites can be attributed to the improved structural integrity of the composites.

Abstract: High speed steel (HSS) with controlled micropores was prepared via vacuum sintering process, using the mixture of stearic acid, TiH₂ and CaCO₃ compound as pore-forming agent. A self-made vacuum high pressure infiltration furnace was used to infiltrate the preform with 60Pb40Sn40-15Ag-0.5RE solid lubricants to create self-lubrication composite where both solid lubricant phase and matrix phase were interpenetrating throughout the microstructure. Effects of pore-forming agent on micropore structure and porosity of the prepared microporous HSS preforms were investigated. The scanning electron microscope (SEM) observation was applied to the test samples and it revealed that the micropores of the microporous materials exhibited a uniform distribution and the apertures were of almost same size in principle. The friction and wear behaviors of the composite sliding against ZrO₂ ceramic under a load of 50 N at 600 °C were investigated using a pin-on-disk wear tester and the results showed that this kind composite possessed excellent high temperature self-lubrication properties.

Abstract: In this study, it was the first attempt to fabricate Ni-P-PTFE composite coatings on titanium alloy (manufactured through electroless composite plating). The effects of suspended PTFE concentration, temperature and surfactant concentration in the plating solution on the PTFE content in the resulting coatings were investigated. In addition, the friction and wear properties of the samples were analyzed. The results showed that co-deposition of Ni-P and PTFE can obviously decrease the friction coefficient of the coatings, reduce wear and improve lubricating property of the coatings.

Abstract: In this paper, nickel coatings (on phosphor bronze substrates) were prepared using pulse electrodeposition method. The friction and wear behaviors of nanocrystalline nickel coating compared with coarse-grained nickel coating against AISI 52100 steel were investigated using l-butyl-3-octylimidazolium tetrafluoroborate ionic liquid and perfluoropolyether as a reference lubricant on reciprocating ball-on-flat UMT-2MT sliding tester. The morphologies of the worn surfaces were observed using a scanning electron microscope. The chemical states of several typical elements on the worn surfaces were examined by means of X-ray photoelectron spectroscopy. The results indicated that NC nickel coatings have better tribological properties than that of coarse-grained nickel coatings under lubricated conditions. This was partly attributed to the high hardness of the NC nickel coating and L-B408 ionic liquid formed tribochemical reaction films under NC nickel coatings.

Abstract: The friction and wear properties of carbon fibers (CF) reinforced polypropylene (PP) composite were studied. The influences of the fiber volume fraction, load applied, rotating speed, and wear mechanism were discussed. The results indicated that CF/PP composite had better tribological properties than pure PP. The friction coefficient and wear mass loss decreased with the fiber volume fraction increased, but increased as the load and rotating speed increased, respectively. CF reduced direct contact between the matrix and counterpart and improved the wear resistance of CF/PP composite greatly. The wear displayed a linear evolution in all the range of load. Surfaces after wear tests were characterized using scanning electron microscopy (SEM).