摩擦诱导生物燃料碳烟微粒组分与结构变化机制研究

摩擦会诱导碳烟微粒参与润滑膜形成,但对润滑界面碳烟微粒组分和结构变化研究较少.为了进一步丰富碳烟摩擦学理论,在端面摩擦试验机上,分别以3%(质量分数)生物燃料碳烟(BS)污染的液体石蜡和CD SAE 15W-40全配方油为润滑油,探索了摩擦力诱导及Ti F3和Fe F3的催化作用下,BS微粒组分和结构的变化情况.利用XPS对摩痕区域表面膜碳元素Csp2和Csp3含量进行了定性定量表征;利用拉曼光谱仪分析了表面膜碳烟微粒结构变化,并对BS微粒组分和结构变化机制进行了讨论.结果表明:在294 N、1 500 r/min,催化剂Ti F3和Fe F3存在下,无定型碳含量降低(R3降低),表面有序化石墨烯含量明显增多(ID2/IG’增加),表面石墨烯缺陷位点明显增多(ID1/IG’).碳烟微粒在摩擦剪切及摩擦热的作用下,其外层结构容易发生剥离并在摩擦副表面形成润滑膜,然后因Ti F3和Fe F3的催化作用,润滑膜中碳元素会向有序化石墨烯转化.

Friction-Induced Structure and Composition Change Mechanisms of Bio-Fuel Soot Particles

Friction-induced the formation of lubricating film including the engine soot particles had been researched extensively, but the composition and structure change mechanisms of soot particles on wear zone were limited. An end-face tribo-meter was utilized to investigate the composition and structure change mechanisms of biomass fuel soot(BS) particles in lubrication oils(such as liquid paraffin and fully formation engine lubricating oil) with and without TiF₃ or FeF₃ at rotation speed 1500 r/min and load 294 N for 60 min. The variations of composition and structure of BS particles on the wear zones were characterized by the X-ray photoelectron spectroscopy and Raman spectroscopy, moreover, the corresponding mechanisms were also discussed. Results show that the structure variation of BS particles, i.e. decrease of the amorphous carbon content(R3), increase of the order graphene content(I_D2/I_G'') and increase of the surface defect sites of graphene(I_D1/I_G''), were observed on the wear zones. The mechanisms of structure and composition change of BS particles were ascribed to friction-induced the peeling of outer layer of BS particles and friction heat on the wear zones resulting in the formation of the better boundary lubrication film. TiF₃ and FeF₃ promoted the increase of graphene micro-crystal content on the wear zones at some conditions.