Study On Tribological Properties Of Different Morphology Micro/Nano-scale WS₂ As Lubricant Additives

The modern large-scale mechanical equipment is developing in the extreme direction of high-speed and heavy-load,which imposes higher requirements on the antifriction performance and environmental protection performance of lubricants.Therefore,the traditional additives are facing great challenges.In this paper,a new type of nano-solid lubricant additive with excellent wear and friction reduction performance,high load-carrying capacity and environmental protection performance was studied.The tribological properties of tungsten disulfide?WS₂?as a lubricant additive were investigated,and the lubrication mechanism was discussed.The main contents and conclusions of the paper include:?1?Two forms of WS₂ were prepared by solid-phase method and hydrothermal method.The micro-morphology and phase composition of the synthesized WS₂ were characterized by XRD,TEM and SEM.The results showed that the lamellar WS₂ with high purity,high crystallinity and obvious hexagonal layered structure was prepared by solid state method,with a thickness of about 2?m and a lateral dimension of between5?m-10?m.The spherical WS₂ was prepared by hydrothermal method,and its average particle size distribution is about 90 nm.?2?The prepared different forms of WS₂ were added to the base oil according to a certain proportion,and the tribological properties of the WS₂ were tested on friction testers.The effects of addition amount,sliding velocity and load on the tribological properties of WS₂ were studied,and the lubrication mechanism of WS₂ with different morphologies as additives was preliminarily discussed.The results showed that the best anti-wear and anti-friction performance were achieved when the amount of lamellar WS₂ was 0.5wt.%and the amount of spherical WS₂ was 1wt.%.The sliding velocity has little effect on the anti-friction and anti-wear properties of different formsWS₂.It can exert its anti-friction and anti-friction effects within a wide sliding speed range.The effect of load on the anti-friction and anti-wear properties of different forms WS₂ was obvious.It can show excellent anti-wear and anti-friction performance under proper load.The average value of the minimum friction coefficient of the lamellar WS₂ is concentrated at the load of 100 N,and the average value of the minimum coefficient of friction of the spherical WS₂ is concentrated at the load of 120 N,which indicates that the extreme pressure performance of the ball-shaped WS₂ is superior to that of the lamellar WS₂.?3?The ionic liquid was used as a dispersant to modify WS₂.The effects of ionic liquid on the dispersion and tribological properties of WS₂ were studied.Using the traditionally used anti-wear agent ZDDP as another additive,the effects of different forms of WS₂ and ZDDP as additives on the tribological properties of the lubricating oil were studied,and the mechanism of action was explored.The results showed that the addition of ionic liquid?[Emim]OTF?can delay the precipitation of WS₂,and can further improve the anti-friction and anti-wear performance of the lubricating oil.There is a synergistic effect between the anti-wear agent ZDDP and different forms WS₂,and the addition of ZDDP can further improve the tribological properties of the lubricating oil compared to the sample oil only added with WS₂.Compared with the base oil,the anti-friction performance of additive-containing sample oil would be more obvious with the increase of the velocity,and the participation of additives can weaken the impact of sliding velocity on wear.