【作者】 杨帆；

【导师】 樊小强； 李浩；

【作者基本信息】 西南交通大学 ， 材料工程（专业学位）， 2022， 硕士

【摘要】 固-液复合润滑系统所具有的低摩擦和低磨损倍受关注。然而,固体润滑材料以及液体润滑材料自身特性对固-液复合润滑系统摩擦学性能的影响仍未得到充分的研究。本论文基于两种氯化胆碱基低共熔溶剂进行固-液复合润滑设计,分别对无机和有机涂层与氯化胆碱基低共熔溶剂所构筑的固-液复合润滑系统进行研究。主要研究内容和结果如下:（1）探究氯化胆碱-尿素/硫脲对W-DLC薄膜摩擦学行为的影响,并系统研究W元素对DLC薄膜力学性能、润湿性以及结构的影响。研究发现随着W元素的掺杂,薄膜从多孔松散的柱状结构逐渐演变为致密的无定形结构。此外,W-DLC薄膜的机械性能随W浓度的增加逐渐增加,并且氯化胆碱-尿素/硫脲在W6DLC（W含量为50.3 at.%）表面的接触角较高。干摩擦时,WO_x和表面石墨化共同导致摩擦的减少,然而WC含量的增加,有利于磨粒磨损的发生。氯化胆碱-尿素/硫脲润滑下,系统优异的摩擦学性能与薄膜的力学性能几乎没有关系,更多的归因于摩擦界面上的界面润湿性和摩擦膜的生成。（2）探究氯化胆碱-尿素与环氧涂层固-液复合润滑的机理。通过与传统润滑油（PAO）润滑对比发现,氯化胆碱-尿素的润滑机理与PAO在润滑中剪切位置在PAO液体内部的机理不同,氯化胆碱-尿素与环氧涂层固-液复合润滑体系的剪切发生在氯化胆碱-尿素与环氧涂层的界面。基于此,氯化胆碱-尿素和环氧涂层的复合润滑系统展现出长寿命、高承载和低摩擦的特点。水的加入会破坏低共熔溶剂的氢键网络结构,从而影响其粘度,导致所形成的低共熔溶剂液膜承载能力降低,对偶直接接触,进而导致摩擦磨损增加。（3）探究固体填料（MoS₂和石墨）含量对环氧涂层力学性能及摩擦学性能的影响,并研究其与氯化胆碱-尿素固-液复合润滑的摩擦学行为。结果表明:MoS₂和石墨的加入对环氧涂层机械性能有明显的影响,但对润湿性影响不大。干摩擦下,涂层机械性能的提高和形成的摩擦膜是减摩抗磨的关键。氯化胆碱-尿素润滑下,纯环氧涂层质地软,有利于分散应力,从而具有低摩擦磨损。添加填料提升了涂层的力学性能,但不利于赫兹接触应力的分散,使得摩擦磨损增大。然而,添加填料的涂层在摩擦过程中形成的摩擦膜可以与氯化胆碱-尿素协同作用,一定程度上起到了减摩抗磨的作用。更多还原

【Abstract】 Solid-liquid composite lubrication system has attracted much interest for low friction and wear.Nevertheless,it is still not well comprehended that the effect of the properties of solid lubricating materials and liquid lubricating materials on the tribological performance of solid-liquid composite lubrication system.The thesis designed solid-liquid composite lubrication systems based on two choline chloride-based deep eutectic solvents.The solid-liquid composite lubrication systems constructed by inorganic and organic coatings with choline chloride-based deep eutectic solvents were studied,respectively.The main research results are as follows:（1）The effect on tribological properties of W-DLC by two deep eutectic solvents was evaluated.Additionally,the effect of W elements on DLC structure,mechanical properties and wettability were systematically investigated.The results show that the doping of W elements evolved the DLC from a porous and loose columnar structure to a dense amorphous structure.Besides,the mechanical properties of W-DLC increase with W concentration.The contact angles of the choline chloride-urea/thiourea on W6DLC（W content is 50.3 at.%）are much higher than other coatings.Under dry friction,friction reduction is contributed by both formation of WO_x and graphitization.The increase in WC carbides contents,which is conducive to the occurrence of abrasive wear.Under choline chloride-urea/thiourea lubrication,the excellent tribological properties of the system is almost no relationship with the mechanical properties of coating,it is more ascribed to the interface wettability at the friction interface or the generation of a tribo-film on the sliding interface.（2）The lubrication mechanism of choline chloride-urea and epoxy coating solid-liquid composite lubrication systems was explored.By comparing with conventional lubricant（PAO）,it was found that the lubrication mechanism of choline chloride-urea was different from PAO.In the PAO and epoxy coating solid-liquid composite lubrication system,the shearing location is inside the PAO liquid.However,in the choline chloride-urea and epoxy coating solid-liquid composite lubrication system,the shearing occurs at the interface of the choline chloride-urea and epoxy coating.Therefore,the choline chloride-urea and epoxy coating solid-liquid composite lubrication system have the characteristics of long life,high load-bearing and low friction.The tribological properties of solid-liquid composite lubrication system are less influenced by viscosity.The water will disrupt the hydrogen bonding network structure of the deep eutectic solvent,which in turn affects its viscosity and reduces the bearing capacity.This result leads to direct contact of tribo-pairs and make the friction and wear increase.（3）The effect of filler（MoS₂ and graphite）content on mechanical and tribological properties of the epoxy coating was investigated.Furthermore,the tribological behaviors of these coatings and choline chloride-urea solid-liquid composite lubrication were explored.The results show that the addition of filler resulted in significant effects on epoxy coating mechanical properties,but elicited little effect on wettability.Under dry friction,the improvement of coating’s mechanical properties and the formation of tribo-film is the key to anti-friction and anti-wear.Under choline chloride-urea lubrication,the pure epoxy coating is soft,which facilitates stress dispersion and thus has the lowest friction and wear reduction.The addition of filler enhances the mechanical properties of coating,but is unfavorable for dispersing contact stresses.This results in a thinner liquid lubrication film and makes tribo-pair easily direct contact,leading to increased friction and wear.However,the tribo-film played a synergistic with choline chloride-urea to anti-friction and anti-wear effects.更多还原