过渡金属氮化物纳米复合薄膜固-液摩擦界面自催化效应及多尺度润滑机理研究

Because transition metal nitrides nanocomposite films are effective as antiwear coating on mechanical components and may catalyze the lubricating fluid to form a self-lubricating film on the counterparts during the sliding process, the project focus on the preparation of the nanocomposite coatings by PVD and endows the as-prepared composite coatings with high hardness, high toughness, and super anti-wear and friction-reducing ability by incorporating other elements and constructing the multiple microstructures. The microstructures, mechanical properties and tribological properties of the as-prepared nanocomposite coatings will be evaluated to establish their relationships and to explain the strengthening mechanism of the nanocomposite coatings by doping other elements and by tailoring the microstructures. The friction and wear behaviors of the nanocomposite coatings lubricated with various lubricating fluids will be studied to illuminate the friction-induced catalysis of the nanocomposite coatings to the lubricating fluids. The formation mechanism of the self-lubricating film formed on the counterpart surfaces caused by the friction-induced catalysis will be evaluated by experimental characterizations and theory analysis. Effect of the coating microstructures, the lubricant properties and the tribo-test conditions on the formation mechanism and the microstructures of the self-lubricating films, the multi-scale lubricating behaviors at the solid-liquid friction interface, the evolution of the friction interface with increasing sliding time will be discussed in detail. The project provides an important theoretical basis for fabricating the composite coatings with friction-induced catalytic activity and for constructing the multi-scale lubrications for sliding counterparts.

基于过渡金属氮化物纳米复合薄膜作为机械部件耐磨涂层的重要应用价值及其对润滑介质潜在摩擦催化形成自润滑膜效应的研究背景，本项目拟采用PVD制备并通过元素掺杂、多层结构控制设计出高硬度、高韧性、耐摩擦磨损的过渡金属氮化物纳米复合薄膜。分析不同制备技术获得过渡金属氮化物纳米复合薄膜的微结构、力学性能及摩擦学性能，并揭示他们之间的构效关系，揭示元素掺杂和结构调控对纳米复合薄膜的强化机制。系统研究纳米复合薄膜在多种润滑介质中的摩擦磨损行为及对润滑介质的摩擦催化效应，采用试验表征及理论分析揭示摩擦界面自催化润滑膜的形成机制，揭示纳米复合薄膜组分及微结构、润滑介质特征及摩擦测试条件等对摩擦界面润滑膜自催化形成机制及其结构特征，纳米复合薄膜的固-液多尺度润滑行为，摩擦磨损界面变化等的影响机理。本项目的实施为制备具有摩擦催化活性的薄膜材料及设计多尺度协同润滑方案提供重要的理论基础。

基于过渡金属氮化物纳米复合薄膜作为机械耐磨涂层的重要应用价值及其对润滑介质的摩擦诱导催化效应，本项目采用物理气相沉积制备技术，通过元素掺杂及多层结构调控的方式，制备了多种过渡金属氮化物纳米复合薄膜(TiAlN/W2N纳米多层薄膜及CrCN、MoN-Cu及MoN-Ag元素掺杂纳米复合薄膜)，揭示了工艺参数（包括原材料组分）对制备的各种过渡金属氮化物复合薄膜组分及微观结构（包括多层复合结构、纳米晶/非晶界面结构、纳米晶分布情况、纳米晶的结晶取向以及晶粒尺寸等）的影响及影响机制。通过力学性能及常规条件下摩擦学性能测试，发现了纳米复合薄膜的元素掺杂种类、含量，以及多层结构的调制周期等对薄膜的硬度、弹性模量、膜基结合力以及常规条件下的摩擦磨损性能有显著影响，阐明了元素掺杂及多层结构调控对纳米复合薄膜强韧化以及耐磨性能提升的影响机制，并建立了过渡金属氮化物纳米复合薄膜制备工艺参数-微观结构-力学性能-摩擦学性能间的构效关系，实现了具有优异力学性能和摩擦学性能的过渡金属氮化物纳米复合薄膜的可控制备。此外，系统研究了几种活性纳米复合薄膜（MoN/Pt、MoN-Ag）在不同摩擦条件的摩擦磨损行为及摩擦诱导催化效应。发现活性薄膜MoN/Pt对润滑介质PAO10具有摩擦诱导催化效应，可以在宽松的摩擦条件下诱导PAO10发生降解并原位形成不定型非晶碳膜。采用分子动力学模拟分析了MoN/Pt活性薄膜摩擦诱导PAO10发生催化降解的过程，阐明了纳米活性薄膜MoN/Pt摩擦诱导PAO10催化降解的发生机制，揭示了PAO10在摩擦力及纳米薄膜中活性元素的催化作用下发生了脱氢、碳链断裂以及含碳碎片重新形成不定型碳膜的过程。进一步研究发现了润滑介质分子结构和摩擦载荷对活性薄膜MoN-Ag摩擦诱导催化效应有显著影响。活性薄膜MoN-Ag对十八烷、十八烯和油酸均有摩擦诱导催化效应，都在摩擦副表面形成洋葱状非晶碳膜，其中对含单键的十八烷呈现出最好的摩擦诱导催化效果，对含C=C双键的十八烯表现出较差的摩擦诱导催化效果。此外发现，载荷增大有利于MoN-Ag薄膜摩擦诱导润滑介质降解形成洋葱状非晶碳膜。该项目的研究成果为制备具有摩擦催化活性的薄膜材料及设计多尺度协同润滑方案提供重要的理论基础。