Current Issue : April - June Volume : 2019 Issue Number : 2 Articles : 5 Articles
Piston ring and cylinder liner (PRCL) interface is a major contributor to the overall frictional and wear losses in an IC engine.\nPhysical vapor deposition (PVD) based ceramic coatings on liners and rings are being investigated to address these issues. High\ntemperature requirements for applications of conventional coating systems compromise the mechanical properties of the substrate\nmaterials. In the current study, experimental investigation of tribo-mechanical properties is conducted for various titanium nitride\n(TiN) coated PRCL interfaces in comparison with a commercial PRCL system. Low-temperature PVD based TiN coating is\nsuccessfully achieved on the grey cast iron cylinder liner samples. Surface roughness of the grey cast iron cylinder liner substrates\nand the thickness of TiN coating are varied. A comprehensive comparative analysis of various PRCL interfaces is presented and all\nthe trade-offs between various mechanical and tribological performance parameters are summarized. Coating thickness between 5\nand 6 micrometres reports best tribo-mechanical behaviour. Adhesion and hardness are found to be superior for the TiN coatings\ndeposited on cylinder liner samples with higher roughness, i.e., - 5-micron Ra.Maximum 62 % savings on the COF is reported for\na particular PRCL system. Maximum 97% saving in cylinder liner wear rate is reported for another PRCL system....
Coatings are normally employed to meet some functional requirements. There is a kind\nof self-generated coating during use, such as the transfer layer during sliding, which may greatly\naffect the tribological behavior. Although the transfer layer has aroused much attention recently,\nthe formation of the transfer layer closely depends on the service conditions, which need to be\nfurther studied. In this paper, the effects of sliding speed, normal load, and duration of wear test\non the transfer layer thickness during friction of Ni/PTFE (Polytetrafluoroethylene) composites\nwere experimentally investigated. The formation mechanism of transfer layer and the relationships\nbetween tribological properties and transfer layer thickness were analyzed in detail. It was found\nthat the transfer layer thickness increased with increases of sliding speed and normal load; and after\na period of wear test, the transfer layer thickness remained stable. The transfer layer thickness\ncorrelates linearly with the friction coefficient and wear volume of the PTFE composites. With the\nincrease of the transfer layer thickness, the friction coefficient decreased, while the wear volume\nincreased, which means that a uniform, thin, and stable transfer layer is beneficial for the reduction\nof friction and wear of the polymeric composites....
In order to improve the friction and wear performance of textured port plate pair, effects of the micropit depth on the tribology\nperformance is studied in the paper. The relation between the micropit depth and the port plate pairâ??s oil loading carrying capacity\nis analyzed in theory; with the friction coefficient, the wear volume and the surface roughness as the evaluation criteria, effects of\nthe micropitsâ?? depth on the tribology performance are investigated. The conclusions are shown as follows: oil loading capacity\nwould come to its peak when the oil film thickness is equal to the micropit depth; the optimal micropit depth is unrelated to the\narea ratios and micropitsâ?? diameters. With the same parameters, the effects of antifriction is optimal when the micropitsâ?? depth is..............
The friction of road surface covered by snow or ice is very low and that results\nin reducing vehicle traction forces and potential traffic accidents. In\ngeneral, to establish a master curve on a rubber-ice friction model is difficult\nbecause the ice surface, being not far removed from its melting point, reacts\nitself very sensitively to pressure, speed, and temperature changes. In this paper,\nan acceptable frictional interaction model was implemented to finite\nelement method to rationally examine the frictional interaction behavior on\nice between the tire and the road surface. The formula of friction characteristic\naccording to temperature and sliding velocity on the ice surface was applied\nfor tire traction analysis. Numerical results were verified by comparing\nthe outdoor test data and it was confirmed to indicate similar correlation. It is\nfound that the rubber-ice friction model will be useful for the improvement\nof the ice traction performance of tire....
In order to improve the friction performance of the valve plate and improve\nthe oil film bearing capacity of the valve plate, the influence of the fluid-solid\ncoupling on the performance of the oil film of the valve plate was studied.\nThe lubrication characteristics of the surface texture of the valve plate were\nstudied systematically based on the theory, simulation and coupling effects.\nIn this paper, the geometrical model of hydraulic drive valve plate is established,\nand the thickness and pressure equation of hydraulic film are deduced\ntheoretically. The Reynolds equation is solved by the finite difference methods.\nThe film thickness and pressure distribution under fluid-solid coupling\nof the port plate pair are obtained, and the correctness of the theory and programming\nis analyzed....
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