Regulation And Mechanism Study Of The Performance Of Ti₃C₂T_x Lubrication Additive

At present,the research of Ti₃C₂T_x as a liquid lubricating additive is still in its infancy,and there are some problems such as ambiguous relationship between Ti₃C₂T_x structure and its lubricating properties,poor dispersion stability in base oil,and ambiguous lubrication mechanism.Based on the above problems,this paper took Ti₃C₂T_x as the research object,and designed and synthesized Ti₃C₂T_x with various structures.Ti₃C₂T_x materials with different structures were introduced into PEG200 as lubricating additives and their tribological properties were tested to explore the effect of Ti₃C₂T_x structure on their tribological properties.In addition,few-layer Ti₃C₂T_x/Mo S₂ heterojunctions were synthesized to enhance their dispersion stability in non-polar base oil,and to exert the synergistic lubricating effect of Ti₃C₂T_x and Mo S₂ to enhance the tribological properties.The main research contents and conclusions are as follows:（1）Modulation of Ti₃C₂T_x layers to enhance its tribological properties in PEG200:Single-layer,few-layer and multi-layer Ti₃C₂T_x with thicknesses of 1.9 nm,4.7 nm and 37.2 nm were successfully prepared by different ultrasonic time and centrifugal speed,and the number of layers was presumed to be 1,3 and more than 15 layers,respectively.The Ti₃C₂T_x with different layers as PEG200 lubrication additive are effective in improving the friction and wear reduction performance of PEG200.Among them,the most excellent 0.3 wt%of few-layer Ti₃C₂T_x reduced the average friction coefficient and wear volume by 13.5%and 61.2%,respectively,compared with pure PEG200.This excellent tribological performance is mainly attributed to the high interlayer spacing,relatively smooth surface and low shear strength of few-layer Ti₃C₂T_x,which make it prone to interlayer slippage,which makes it easier to form a uniform and dense friction film at the friction interface.Therefore,it has the best anti-friction and anti-wear properties.（2）Modulation of Ti₃C₂T_x size to enhance its tribological properties in PEG200:Spherical Ti₃C₂T_x quantum dots（MQDs）with a particle size of about 6 nm were prepared by hydrothermal method.The addition of MQDs greatly improved the tribological performance of PEG200,reducing the average friction coefficient and wear volume by 18.3%and 63.5%,respectively,under 40 N load compared with pure PEG200.MQDs can form an adsorption film through electrostatic adsorption,and provides a rolling effect to reduce friction and repair the worn interface,thereby effectively reducing friction and wear.（3）Construction of few-layer Ti₃C₂T_x/MoS₂ heterojunctions to enhance their tribological properties in non-polar transmission oils:Few-layer Ti₃C₂T_x/Mo S₂ heterojunctions were fabricated by hydrothermal method,in which Mo S₂ nanosheets were vertically and uniformly grown on the surface of few-layer Ti₃C₂T_x nanosheets.The steric hindrance effect of vertically grown Mo S₂ enhances the dispersion stability of the heterojunction in non-polar 150N base oil.The lubricating performance of the few-layer Ti₃C₂T_x/Mo S₂ heterojunction in 150N is better than that of the few-layer Ti₃C₂T_x,Mo S₂ and their mechanical mixtures,indicating the synergistic lubrication of Ti₃C₂T_x and Mo S₂ in the heterojunction.The introduction of 0.3 wt%few-layer Ti₃C₂T_x/Mo S₂ heterojunction in 150N can reduce the friction coefficient and wear volume by 38.8%and 83.5%,respectively.The good dispersion performance of the few-layer Ti₃C₂T_x/Mo S₂ heterojunction enables the additive to smoothly enter the friction interface,and the friction-induced structural evolution can effectively make the Ti₃C₂T_x/Mo S₂ fill the micro-pits to repair the friction interface and reduce the roughness.After frictional heat and high pressure,a Ti₃C₂T_x/Mo S₂ deposition film and tribochemical film composed of Mo O₃,Fe SO₄,and iron oxide were formed,which enhanced the interaction of the sliding interface,thereby effectively reducing friction and wear.