碳基薄膜表/界面化学特性与其超滑行为的相关性研究

Carbon based films have excellent physical, mechanical and tribological properties, and they are wide used in fields like aerospace, mechanical equipment, MEMS, precision manufacturing as solid lubricant. Due to the variation of sp2 hybrid, sp3 hybrid and H content in carbon based films, their friction coefficient can vary in more than one order of magnitude (10-1~10-3). This strongly limited their application in different atmospheres (such as on earth and space environments) and the understanding of their friction mechanism. Considering the surface/interface chemical characteristics of different carbon based films, this project aims at designing, preparing three types of self-mated carbon based films, and investigating the ad-/de-sorption of gas molecules with different polarity and electronic structures on these three types of carbon-based films, and revealing the evolution mechanism of friction interface electron density changing caused by surface/interface chemical characteristics and adsorption. By clarifying the molecules’ adsorption energy values and cross-interfacial bonding behaviors, the correlation between weak interfacial interaction and the superlubricity behaviors of carbon based films was established. Combined with the first-principle and DFT calculations, the friction mechanism of different carbon based films are investigated at nano-scale was understood, and the physical origin of carbon based films’ superlubricity was studied. The results can provide theoretical guidance for designing multi-environmental adapted superlubricity carbon based materials.

碳基薄膜具有优异的物理、机械及润滑性能，在航空航天、机械装备、精密制造等领域作为固体润滑材料具有广泛应用。但其摩擦学行为由于sp2C、sp3C杂化键以及H含量差异而对气氛环境具有敏感性，摩擦系数呈跨数量级差异（10-1~10-3）。这极大阻碍了碳基薄膜跨环境超滑的发展，同时制约了对其摩擦机理的认识。鉴于此，基于对碳基薄膜表面化学特性的分析，本项目设计、制备三类不同表面化学特性的碳基薄膜自配副系统，研究不同极性和电子结构的气体分子在其表面的吸/脱附规律，揭示表/界面化学特性和分子吸附导致的摩擦界面电子密度演变机制；在明确分子吸附能值和跨界面化学成键机制的基础上，建立本征特性、界面弱作用与碳基薄膜超滑行为的相关性。结合理论计算，从分子水平揭示碳基薄膜在不同气氛下摩擦系数呈跨数量级差异的本质原因，理解碳基薄膜超滑行为的物理起源，为设计跨环境碳基超滑系统提供重要的理论支持。

碳基薄膜是最有希望实现宏观超滑的固体润滑材料之一。界面化学特性是碳基薄膜超滑的关键因素，理解界面化学特性与超滑行为的相关性，是揭示碳基薄膜超滑本质的必要基础。通过本课题的研究，设计、制备了三类不同化学特性的摩擦界面，验证并揭示了不同极性和电子结构的气体分子在滑动界面上的吸附状态以及动态吸、脱附对碳薄膜摩擦学行为的影响机制，归纳、统一了不同配副下界面结合能与摩擦行为的相关性，从分子水平阐述和理解碳基薄膜在不同气氛下的摩擦机理。研究了类富勒烯微结构的纳米裁剪过程，建立了沉积关键参数和类富勒烯尺寸和空间构型的关系，实现了系列超滑碳基薄膜的制备技术突破，解析了超滑界面结构演化的动态过程，建立了奇/偶元碳环与超滑行为的内在关系。提出了一种室温生成纳米金刚石微结构的新策略，揭示了亚稳态碳结构与非晶碳的结构演变机制，揭示了超晶纳米金刚石颗粒的动态生长过程。建立了气体吸附能与碳基薄膜超滑行为的相关性，揭示了无/含氢碳膜摩擦系数大小差异的物理化学本质。本项目研究成果为固体超滑薄膜结构设计提供方法基础和理论指导，具有重要的学术价值和应用前景。