金属纳米添加剂在碳基薄膜固液复合润滑体系中的作用机制

DLC-based solid-liquid synergetic lubricating system has wide application prospect in the fields of aviation, automobile because of its outstanding antifriction and antiwear properties. The existing additives with sulfur and phosphorus groups which are designed on the basis of interaction with the metal surface cannot match the DLC-based films and lead to environment pollution. It is urgent to develop environment friendly additive suitable for DLC-based solid-liquid synergetic lubricating system. Based on the activity of metal nano-particle with both DLC-based film and metal materials, a new way is provided aiming at developing environment friendly additive for the DLC-based solid-liquid synergetic lubricating system. Through the study of action mechanism of three kinds of metal nano-particle including Cu, Ni, Bi modified with oleic acid and oleyl amine with DLC-based film in this system, the lubricating mechanism of different metal nano-particles act as additive in this system is investigated. Density Function theory is applied to study the friction reaction mechanism of different metal nano-particles in order to establish theory model of metal nano-particles act as additives in DLC-based solid-liquid synergetic lubricating system, and provide technical support and theoretical basis for the design, synthesis of metal nano-particle as environment friendly additives in DLC-based solid-liquid synergetic lubricating system.

碳基薄膜固液复合润滑体系优异的摩擦学性能，使其在航空、汽车等领域具有广阔的应用前景。现有添加剂的设计都是基于与金属表面的相互作用，与碳基薄膜不匹配，且多为硫磷化合物污染环境，急需发展环境友好的针对碳基薄膜固液复合润滑体系的润滑油添加剂。利用金属纳米微粒既可以与碳膜产生强的物化作用又可与金属形成紧密结合的特性，为研发针对碳基薄膜固液复合润滑体系的环境优好型添加剂提供一条新途径。通过研究无硫磷基团的油酸油胺修饰的Cu、Ni、Bi三种类型金属纳米微粒在体系中与碳膜的作用机制，探讨碳膜固液复合润滑体系中三种不同金属纳米微粒的润滑机理。利用泛函理论计算不同类型金属纳米微粒的摩擦反应机制，量化关联金属纳米微粒的电子结构与其润滑机制的关系，建立金属纳米微粒作为碳基薄膜固液复合润滑体系添加剂的润滑理论模型，为设计、合成针对该体系的金属纳米微粒添加剂提供有效的技术支撑和理论依据。

本项目的研究内容主要是围绕如何利用金属纳米微粒既可以与碳膜产生强的物化作用又可与金属形成紧密结合的特性，来解决碳基薄膜固液复合润滑体系与现有小分子润滑油添加剂不匹配的问题。本项目通过原为表面修饰法控制合成制备了平均粒径分别为4纳米和8纳米的Ni、Cu纳米微粒，使其在基础油中表现出了优异的分散稳定性。对商用超细纳米铋粉进行表面修饰使其能够在基础油中稳定分散。研究了纳米微粒的种类、表面修饰剂、在三类（金属、非金属以及氢掺杂），硬度范围在6-23GPa的碳膜与不同基础油（PAO和DIOS）组成的固液润滑系统中的摩擦学性能及其影响机制。发现Ni纳米添加剂在碳膜固液复合润滑体系的所有润滑区间（边界、混合及弹流润滑）都产生突出的减摩效应，纳米微粒在弹流区产生的平推流效应减小了润滑油分子间的摩擦，在边界区对碳膜的石墨化和对偶钢球的氧化产生了催化作用，使系统减摩达20%，磨损率降低40%。Cu纳米微粒对各种掺杂，宽硬度范围的碳膜都产生突出的减摩抗磨效果，减摩20%，磨损率降低98%。与商用小分子添加剂ZDDP进行了对比研究。Cu纳米微粒克服了ZDDP对摩擦副具有硬度选择性以及高摩擦的缺点。经修饰的超细纳米Bi粉在两种基础油（PAO和DIOS）中都具有突出的减摩抗磨性，表现出了对基础油的普遍适应性，克服了商用小分子减摩剂MODTC对碳膜的腐蚀磨损。通过对三种金属纳米微粒在碳膜固液系统摩擦性能的系统研究发现，三种金属纳米微粒都可以在摩擦表面沉积成膜，表现出了优异的摩擦学性能，可以完全克服商用小分子添加剂对于碳膜的磨粒磨损和腐蚀磨损，有望成为碳膜摩擦副的专用润滑油添加剂。