Papers by Keyword: Solid Lubrication

Abstract: The present work aimed to contribute to the development of high performance self-lubricating sintered composites, with low friction coefficient and high mechanical strength. Self-lubricating composites presenting embedded solid lubricants in a ferrous matrix were produced. Hexagonal boron nitride (hBN) and graphite were the solid lubricants powders added during the mixing step. The composites were processed by conventional powder metallurgy. The liquid phase sintering, by adding copper, improved the degree of continuity of the matrix by rearranging the solid lubricant particles. With this, besides the hardening effect on the matrix, the mechanical properties of the composites were improved, with tensile strength increasing when compared to the same composite without copper. By using the proposed methodologies, optimized composites presenting friction coefficient of 0.12, tensile strength of 500 MPa and scuffing resistance of 29300 N.m were obtained.

Abstract: The wear mechanism of solid lubrication bearing in vacuum environment was researched. It experiment on the angular contact ball bearing of sputter-deposited MoS2 solid lubrication coating in bearing friction test device, and the time-varying characteristics of bearing temperature and vibration can be got. The MoS2 solid lubrication coating on bearing surface was gradually wear in the process of bearing rotation, and the temperature and vibration of bearing were increased. The transfer membrane was formation in bearing raceway with the increase of bearing rotation. The transfer membrane accumulation occurs due to uneven thickness of MoS2 solid lubrication coating, and the bearing produce serious vibration. Through the microstructure observation and energy spectrum analysis of the bearing surface, it finds there are pitting caused by fatigue wear and scratch caused by abrasive wear after test. The test result indicate that the wear mechanism of solid lubrication bearing in vacuum environment were fatigue wear of solid lubrication coating caused by steel ball circularly rolling and abrasive wear caused by steel ball sliding.

Abstract: For the purpose of preparing stern bearings adapted to water-lubricating environment to replace natural lignumvitae, preparing bearings with solid lubricant of electromechanical equipment applied in some industries such as textile, food and healthcare to replace sintered bronze, and preparing advanced automotive upholstery, appliance and artware to replace natural rosewood and ox bone, three published patents including “a preparation method of artificial lignumvitae” were used to prepare artificial lignumvitae with a better wear resistance than natural lignumvitae. As the materials for sliding bearing, the main performance of artificial lignumvitae meets the requirement for sintered bronze FZ2365. It explores a new way to develop functional biomass materials with wood waste in urban and rural area while ensure its high quality and cleanness.

Abstract: Cylinder Liner design innovation goal is energy conservation. As the main friction parts engine cylinder liner, reducing friction energy is energy saving basic requirements. Materials research cylinder sleeve is one of the main cylinder liner saving research. Through the piston ring and cylinder liner surface friction dual material hard phase, self-lubricating phase, toughening phase analysis, select compatibility, high strength, heat resistance, good high temperature performance, ease of manufacture, price rational matrix material and an appropriate proportion of nanoscale hard material, self-lubricating materials, ductile materials, using appropriate methods cladding and processing, design developed high-temperature self-lubricating cylinder sets of advanced materials. The latest international high temperature, wear-resistant, self-lubricating materials research: modern nanoα-Al₂O₃+Ni-base alloy composite materials, Ti₂B/Fe metal-ceramic composites, metals and ceramics NiCr-Cr₃C₂ particles CaF₂ self-lubricating composite alloy powder material, NiCr/Cr₃C₂-WS₂ self-lubricating wear-resistant materials were studied and found to TiC, Al₂O₃ is hard reinforcing phase, CaF self-lubricating phase, NiCr/TiC eutectic toughening phase, high-temperature self-lubricating wear-resistant nanocomposite, and Cr₁₈Ni₉ class alloy as base material, by laser cladding method enables conventional cylinder liners manufacturing technological breakthroughs, has practical value.

Abstract: Traditional lubrication by oil sometimes does not work because of the high temperature, fast speed and excessive load of the aeroengine bearings. The Graphite-like Carbon coating is used to improve the insufficient lubrication in this paper. And the micro hardness, the friction coefficient and the wear rate tests are offered: with GLC, the hardness is increased twice at least, its friction coefficient is 25% and the wear rate is 1/100 when contrasted with that of the typical bearings material. The tests and calculation results show:the wear cycles of the GLC coated W9Cr4V is more than 400 times of that of the uncoated W9Cr4V and even when the GLC coating is worn out, the friction coefficient of W9Cr4V is only 0.15 which can effectively lubricate for the bearing for a short period of time when the liquid lubrication does not work. So it is proved to be effective in improving the wear resistance and reliability of bearings.

Abstract: NiCr/Cr3C2-WS2-CaF2 mixed powders were prepared on 1Cr18Ni9Ti stainless steel substrate to fabricate high-temperature self-lubrication wear resistant composite coating by laser cladding. The microstructure of the coating was examined by means of XRD, SEM and EDS. The high-temperature dry sliding friction and wear behavior of the composite coating were evaluated by using a ball-on-block wear tester at room temperature, 300 and 600 , respectively. The results showed that the composite coating had a unique microstructure consisting of γ-(Ni,Fe) solid solution matrix, Cr7C3/WC reinforcement and CrS/WS2 lubricant particles. The hardness of NiCr/Cr3C2-WS2-CaF2 coating by laser cladding was lower than NiCr/Cr3C2 coating, but higher than stainless steel substrate significantly. It was because of the addition of solid lubricant. In the wear process, elevated temperature was helpful to form a lubricating transfer film. As a result, the NiCr/Cr₃C₂-WS₂-CaF₂ coating exhibited a notable anti-friction and wear resistance at 300 and 600 .

Abstract: Embedded solid lubricant materials have good self-lubrication characteristics, which can realize lubrication in special some situations such as low-speed, high-load, high-temperature of the machinery without lubricating oil or grease. This paper presents a review concerning the structure of embedded solid lubrication materials, and its lubricating mechanism, the development of embedded solid lubricant materials, the latest research progress of the influence factors such as different types of metal substrates, mosaic, temperature, load, and porous structure and the application example of bearings. The feasibility of embedded solid lubrication materials which may be used in the mechanical seal face is also analyzed.

Abstract: It is essential to control the heat generated in the cutting zone in order to ensure the workpiece quality after grinding. This article deals with an investigation in using graphite and hexagonal boron nitride as solid lubricants to reduce friction and thereby improve the surface integrity of Ti-6Al-4V alloy. The polymer-based solid lubricant coating wheels have been prepared. Grinding experiments have been conducted to study the effect of the graphite and hexagonal boron nitride lubricants on the grinding temperature and the surface quality of the workpiece while grinding Ti-6Al-4V. Results indicate that there is a considerable improvement in the performance of grinding Ti-6Al-4V using graphite and hexagonal boron nitride as solid lubricants in dry grinding in terms of grinding temperature and surface quality of the work piece. The indigenous polymer-based solid lubricant coatings are effective in dry grinding.

Abstract: The n-SiO2/FeS solid lubrication composite coating is prepared by means of the comprehensive treatment process of gridded laser quenching, low temperature ion sulfuration and vacuum impregnation technology. The tribological properties of n-SiO2/FeS solid lubrication composite coating are investigated under the condition of dry sliding, and the lubrication mechanisms are also preliminary discussed. The experiment results reveal that the friction coefficient of the coating is in the range of 0.065~0.10 when tested in 4067 minutes. Furthermore, its wear rate is only 6% of FeS solid lubrication duplex coating. This is testified that the n-SiO2/FeS solid lubrication composite coating is durable with low friction coefficient and wear resistance.