Current Issue : April - June Volume : 2016 Issue Number : 2 Articles : 8 Articles
Natural Fiber Reinforcement Polymeric Composites (NFRPC) used in the recent days in wide range of industrial\napplications. For its good environmental properties and availability, natural fibers and natural additives used as\nreinforcing material for most of polymeric composites. In the present work, polyester composites filled by date seeds\npowder as a natural filling material were proposed as (NFRPC). Effect of different parameters on the tribological\nbehavior of the proposed composite is studied. The proposed variables are; applied normal load, sliding speed, sliding\ndistance and the percentage of filler contents. Pin on Disk tribometer was designed and constructed for the tribological\nmeasurements. Friction coefficient and rate of wear for the proposed composites have been obtained. The results\nshow that; the coefficient of friction for polyester composites filled with date seed powder decreases by 15% with\nincrease of filler under high contact pressure, beside the increase of velocity increases friction coefficient up to 10%.\nRate of wear decreases to 10E-5 gm-1 with increase of date seed filler up to 10% under low contact pressure and low\nsliding speed, but; unfortunately, continuous increases of date seed filler from 15% to 25% decrease the resistance\nof wear for proposed composites under high contact pressure and high sliding speed. There is a significant effect of\nthe applied load (contact pressure) and sliding velocity on the wear rate of polyester composite filled with date seed....
Hairy nanoparticles, which graft organic chains on nanoparticles, have led to a wide variety of advanced materials and have been\napplied in many fields over the past two decades. In this paper, effects of nanoparticle size and organic chain on the tribological\nproperties of amino functionalized hairy silica nanoparticles (HSNs) were investigated. Silica nanoparticles with different sizes and\namino group organic chains were synthesized and dispersed into polyalphaolefin (PAO) via a modified process. The synthesized\nHSNs were characterized by variety of methods. The tribology properties of those HSNs were investigated using a four-ball\ntribometer. The coefficient of friction and wear scar diameter were measured and analyzed. It was found that the HSNs could\nforma stable homogeneous solution with PAO.The tribological performance of the PAO 100 was enhanced dramatically by adding\nthe HSNs. The data suggested that HSNs with larger size, longer organic chains, and more amino groups gave better antiwear and\nfriction reduction properties than other nanoparticles....
The complexity of thermal elastohydrodynamic lubrication (TEHL) problems has led to a variety of specialised numerical\napproaches ranging from finite difference based direct and inverse iterative methods such as Multilevel Multi-Integration solvers,\nvia differential deflection methods, to finite element based full-system approaches. Hence, not only knowledge of the physical and\ntechnical relationships but also knowledge of the numerical procedures and solvers is necessary to perform TEHL simulations.\nConsidering the state of the art of multiphysics software, the authors note the absence of a commercial software package for solving\nTEHL problems embedded in larger multiphysics software. By providing guidelines on howto implement a TEHL simulation model\nin commercial multiphysics software, the authors want to stimulate the research in computational tribology, so that, hopefully,\nthe research focus can be shifted even more on physical modelling instead of numerical modelling. Validations, as well as result\nexamples of the suggested TEHL model by means of simulated coefficients of friction, coated surfaces, and nonsmooth surfaces,\nhighlight the flexibility and simplicity of the presented approach....
Cemented carbides, also known asWidia, are hardmetals produced by sintering process and widely used in mechanical machining.\nThey show high cutting capacity and good wear resistance; consequently, they result to be excellent materials for manufacturing\ncutting tools and sandblast nozzles. In this work, the wear resistance ofWC-Co carbides containing Eta-phase, a secondary phase\npresent in the hard metals when a carbon content deficiency occurs, is analyzed. Different mixtures of carbide are prepared and\nsintered, with differentweight percentages of carbon, in order to formEta-phase and then analyze howthe carbon content influences\nthe wear resistance of the material. This characterization is carried out by abrasive wear tests. The test parameters are chosen\nconsidering the working conditions of sandblast nozzles. Additional information is gathered through microscopic observations\nand the evaluation of hardness and microhardness of the different mixtures. The analyses highlight that there is a limit of carbon\ncontent below which bad sintering occurs. Considering the mixtures without these sintering problems, they show a wear resistance\ndepending on the size and distribution of the Eta-phase; moreover, the one with high carbon content deficiency shows the best\nperformance....
A Ni-based alloy/nano-h-BN self-lubricating composite coating was produced on medium carbon steel by high velocity oxygen\nfuel (HVOF) spraying technique.The powder feedstocks for HVOF spraying were prepared by ball milling and agglomerated the\nnano-h-BN with Ni-based alloy powders. The microstructure and mechanical properties of coatings have been investigated.With\nthe increasing of h-BN contents, some delaminations appeared gradually in the coatings and a continuous network with h-BN\nphase embedded formed in the metallic matrix. The average microhardness of the self-lubricating coating was a little lower for the\naddition of soft solid lubricant.The friction coefficient of coatings is in the ranges of 0.38ââ?¬â??0.48 and 0.38ââ?¬â??0.52 at ambient temperature\nand 400âË?Ë?C, respectively.The maximum bonding strength of coatings reached 23.83MPa....
The purpose of this study was to determine the optimal design parameters and to indicate which of the design parameters are\nstatistically significant for obtaining a low coefficient of friction (COF) and low wear rate with waste palm oil blended with SAE 40.\nThe tribology performance was evaluated using a piston-ring-liner contact tester.The design of experiment (DOE) was constructed\nby using response surface methodology (RSM) to minimize the number of experimental conditions and to develop a mathematical\nmodel between the key process parameters such as rotational speeds (200 rpm to 300 rpm), volume concentration (0% to 10%\nwaste oil), and applied loads (2 kg to 9 kg). Analysis of variance (ANOVA) test was also carried out to check the adequacy of the\nempirical models developed. Scanning electron microscopy (SEM) was used to examine the damage features at the worn surface\nunder lubricant contact conditions....
Tribological properties of nanolamellar tungsten disulfide doped with zinc oxide\nnanoparticles were studied. Nanolamellar tungsten disulfide and ZnO nanoparticles\nproduced by electrospark erosion of metal granules in an H2O2 solution were analyzed\nusing the XRD, SEM and TEM techniques. According to the tribological measurements,\nZnO nanoparticles did not significantly change the friction coefficient of nanolamellar\nWS2 at 25 �°C in air, whereas they positively impact on wear resistance of nanolamellar\nWS2 at 400 �°C....
True stability of lubricants can be determined when there is minimum change in the contact area and also the intervention of\nwear debris in the contact zone. Here, we have used the ball-on-disk instrument with the migrating point contact, that is, relative\nmotion between the ball and disk condition to fix the contact area and minimize the wear debris at the contact zone. The jump in\nthe friction coefficient indicates the film failure, which appeared earlier for the motor oil 5W30 compared to 5W40. Such profile\nwas not recorded in absence of relative motion. Therefore, 5W40 was considered to have a better lubricant stability than 5W30.\nApplying the same test condition to the natural lubricants shows that glycerol has better lubricant stability than glycerol-water\nmixture. Superior true lubricant stability by glycerol and 5W40 can be related to its high viscosity. However, they were less wear\nresistant compared to low viscosity lubricants like 5W30 and glycerol-water.We suspect the role of microscopic wear debris at the\ncontact zone for this behavior although it should have been avoided in the migrating point contact condition. Overall, ball-on-disk\ninstrument with a migrating point contact condition is an effective technique to determine the stability of lubricants....
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