| The application of the conventional extreme pressure and antiwear additives in oil is restricted because of the improvement of requirements for lubrication performance and environmental performance.Taking the research and development of new nanoparticle lubricant additives which have good anti-wear and friction reducing properties,high load carrying capacity and the environmental performance as background, Experimental Study on the tribological performance of WS2/MoS2compelx nanoparticles has been done,with their synergistic lubrication mechanism discussed.A surfactant named T161was chosen for dispersion stability experiment on nanoparticles of WS2and MoS2,which was under compound action of hign power ultrasonic and ball-milling stir. It is found that the stability is better when the ratio of the nanoparticles and surfactant is2:1. The two kinds of nanoparticles can be evenly dispersed in the lubricant without mutually exclusive.Orthogonal experiment design and the four-ball friction and wear experiments in different operating conditions show that the composite particles of nano WS2/MoS2have better anti-wear and friction reducing properties than the single particle. At low load, compared the two single particle, anti-abrasion and anti-friction effect of the composite particles is not significant, With the load and temperature increasing, anti-wear anti-friction effect become more and more obvious. Under controlled conditions, the rational dosage of the single nano-WS2particle is0.2%, and for nano-MoS2is0.5%. The lubricating oil has better anti-wear and friction-reducing behaviors when the mass ratio of nano-WS2to nano-MoS2is3:1and total weight of composite nano-particles is0.6%.To research the WS2/MoS2complex nanoparticles’mechanisms of action in lubricating oil, series of EDS analysises and XPS analysises were done. And combined with the existing lubrication mechanism of action it is found that:the WS2/MoS2compound nanoadditives play a role in antifriction mainly through the mechanism of physical and chemical film forming.In the initial stage of friction, the friction surface is coated with nano-WS2deposition film and nano-MoS2adsorbed film; With the friction to carry on, the friction surface contain the chemical reaction film and WS2-dominated deposited film; in violent friction period, the deposited nano-WS2in wear marks and pits is activated and has tribochemical reaction affected by high tempetature and high pressure. The resultant of reaction consists of nanometer FeS, nanometer FeSO4and nanometer WO3,which make the protection layer is thicker, and eventually the wear surfaces become smooth. Thereby the anti-wear and friction-reducing performance of the friction pair is improved.Application experiment of composite additives have been done on the self-designed motorcycle engine simulant bench test. Oil collected after the experiment was analysed through the iron and optical spectrum analysis technique. The results show that abrasion loss and wear intensity of friction vice within the engine which was added to WS2/MoS2complex nanoparticles are decreased, the abrasion of piston ring in engine is reduced by33.9%, indicating that the compound additives play a significant anti-wear performance. |
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