大气环境下碳薄膜纳米结构与表面化学协同效应与超润滑相关性研究

The term superlubricity was proposed by Hirano and Shinjo at the beginning of the 1990s to describe a theoretical sliding regime in which the friction between two contacting surfaces nearly vanished. It is generally thought that when the sliding friction coefficient is below 0.01 the lubricating state is considered to be the superlubricity. However, many study focused on solid films with ultralow friction under special conditions. To research the superlubricity of the solid films under atmosphere is serious, which can not only reduce the consumption of friction energy but also provide a near-wearless condition. Carbon based thin films, generally,called diamond like carbon (DLC), are considered as the solid lubricants with super low friction to be used in practice among many solid lubricants after many years investigation. To attained a kind of superlubricity of DLC fims that one must be own special nanostructures, but is not sufficient conditions. Thus, revealing the mechanism of superlubricity DLC fims is of great scientific and practical importance. For this purpose, three kinds of hydrogen carbon film- - traditional amorphous carbon films can reduce friction by means of graphite-like films, multilayer graphene structured carbon films may reduce friction by lubrication of graphene mixed carbon films, and fullerene-like carbon films probably reduce friction by formation of fullerene-like carbon films. Through the active design and preparation of different structure and surface chemical state film, investigation inner structure and surface film chemical state change on the influence of tribological behavior, which will reveal the mechanism of superlubricity under atmospheric environment and provide new explanation to tribology.

目前对大气环境下碳薄膜的超润滑行为的报道很少，研究结果仅限于猜测和理论模拟，尚缺乏统一的具体解释。本项目拟设计制备传统含氢碳薄膜（无纳米结构、硬度中等、弹性差、悬键最多）、含氢多层石墨烯复合碳薄膜（平面石墨片、硬度最低、弹性好、悬键中等）和含氢类富勒烯结构碳薄膜（弯曲片层结构、硬度最高、弹性好、悬键最少），对比研究薄膜纳米结构对摩擦学性能的影响机制；探讨含氢类富勒烯结构碳薄膜本征结构对大气环境下超润滑性能的决定因素，着重考察碳薄膜在摩擦过程中转移膜内在纳米结构演化、表面化学态转变过程对大气环境下超润滑行为的作用机理。通过理论计算、模型再现等手段，最终揭示出大气环境下超润滑碳纳米结构/碳薄膜中微纳米结构与表面化学互动耦合机制。

项目针对大气环境下碳薄膜的超滑行为机理进行了研究，旨在揭示类富勒烯碳薄膜超滑的本质，指导超滑碳薄膜的制备和应用：制备传统含氢碳薄膜（无纳米结构、硬度中等、弹性差、悬键最多）、含氢石墨烯复合碳薄膜（平面石墨片、硬度最低、弹性好、悬键中等）和含氢类富勒烯结构碳薄膜（弯曲片层结构、硬度最好、弹性好、悬键最少），对比研究薄膜纳米结构对摩擦学性能的影响机制。Raman结果显示，H2流量在5SCCM时制备的薄膜更具富勒烯化。摩擦学研究发现，更具富勒烯导致薄膜具有极低的摩擦系数，约为0.005左右，磨损率 1.48x10-8 mm3/Nm。进一步对磨屑进行了Raman和HRTEM分析发现，磨屑中形成的类富勒烯结构更加有序，且出现一小部分的洋葱碳结构。对比本体和磨屑的Raman峰发现，薄膜的本征结构Raman峰更接近于非晶结构，而磨屑Raman峰在出现的尖锐的碳洋葱特征峰，说明磨屑在摩擦力的作用下变得有序，通过滑移和滚动促使摩擦系数急剧降低，从而实现大气下的超滑。