HIPIMS制备环境自适应C/MoSx复合润滑薄膜的界面结构调控及摩擦机理

In some high technology fields, especially under the conditions of high bearing load, high speed, high temperature, the uses of monoclinic carbon based or MoS2 solid thin films are neither possible nor desirable. The friction and wear coefficients of both DLC and MoS2 films were indeed confirmed to be low, but they were also found to be sensitive to the test environments. Recently developed multi-component and multi-layer composite solid lubricant film system has been found to be a new class of smart materials providing impressive friction, wear properties and long lifetime at complex sliding conditions. However, their composition, structure controlling, synthesis and friction sliding mechanism of these multifunctional films still remain unclear. In this study, we employ a hybrid high power impulse magnetron sputtering (HIPIMS) technique, which has a high ionization and advantages in high performance coatings with strong adhesive strength, to produce C/MoSx thin films. Taking use of the synergistic effect on the frictional characteristics due to a combination of multi components, is aimed to improve the environmental adaptation of thin films. The effect of film microsructure on its mechanical properties and tribological behaviors will be investigated. The tribological mechanism of C/MoSx composite structured films will be clarified. Also, the durability and degradation mechanisms of C/MoSx with different structures will be discussed through understanding the micro-structures of lubricants and the physical or tribo-chemical interaction of the lubricant and surfaces. All these works can build a solid basis for further understanding of its tribology under multi test environments and provide guidance to develop lubricants with high quality in a wide range of engineering applications.

在高技术领域装备重载、高速、高温等苛刻工况下，我国现有的单一组分、单一结构的碳基和MoS2润滑薄膜表现出环境敏感性，难以满足复杂多变条件下的润滑性能要求，迫切需要研究具有环境自适应性的纳米复合（多元多层）润滑薄膜材料。其中，复合润滑薄膜的设计制备，组分结构调控，及润滑摩擦行为机理均有待揭示。本项目将围绕环境自适应C/MoSx复合润滑薄膜的设计制备、组分结构调控及其对润滑抗磨损性能的影响规律、磨损失效机理等关键科学问题，采用高离化率的高功率复合磁控溅射（HIPIMS）方法，实现环境自适应C/MoSx 润滑材料的关键制备；利用复合元素之间的协同效应，改善薄膜的摩擦环境适应性；通过对复合薄膜体系在多环境下的摩擦磨损行为和微结构变化的深入研究，分析薄膜摩擦表面所发生的物理及化学作用，研究薄膜组分、结构与性能间的作用关系，揭示其磨损润滑机理。研究结果将为研制发展高性能润滑材料提供理论依据和技术支撑。

针对传统润滑油脂材料或单一组分、单一结构固体润滑薄膜难以满足复杂、多变、苛刻工况条件下的耐磨、润滑、承载性实际需求，围绕新一代C/MoSX润滑薄膜材料的设计制备、界面结构调控及其对润滑性能影响规律的关键科学问题，本项目采用HiPIMS复合溅射技术，基于纳米化、多层化的组分与结构设计理念，实现C/MoSX润滑薄膜材料可控制备；并通过多测试环境下的摩擦磨损行为的深入研究，揭示薄膜组分-结构-性能间的作用规律，阐明相关磨损润滑机理。研究结果为发展高性能润滑材料提供理论依据和技术支撑。首先，对HiPIMS等离子体特性研究表明，近表面区域内等离子体中的活性粒子以Ar+和金属离子为主，但在脉冲电压区金属粒子离化率偏低。与传统直流磁控溅射相比，复合HiPIMS可以促进Ti层晶粒细化，呈现明显择优取向，表面光滑且力学性能更加优异。采用第一性原理理论计算对比Cr、Ti、W过渡层对非晶碳薄膜界面的催化行为， Cr、Ti、W过渡层均可导致碳卷曲结构形成，但在低温下Ti具有较好的石墨化转变催化行为；而Cr、W过渡层具有较好的石墨化高温催化性能，且石墨化含量的增加归因于sp3-sp2转变和弱Me-C键态结构稳定性；相关结果与实验结果相吻合，可为非晶碳基薄膜强过渡层界面的选择提供理论指导。.HiPIMS共溅射技术制备 Ti/C-MoSx复合润滑薄膜呈致密的非晶结构，即非晶MoS2弥散在非晶碳基体中。致密结构使其具有优异的机械性能，有利于获得良好摩擦特性。C/MoSx薄膜在多测试环境下的摩擦特性研究表明：大气环境下碳含量较高的薄膜具备更优异的摩擦学性能，通过对磨损界面与摩擦产物的分析，发现非晶碳的石墨化与非晶MoS2的有序化以及转移膜释放非晶碳等机理协同作用，导致了MoS2/C低摩擦磨损行为；真空环境下，非晶碳的粘附作用导致含量较高的MoS2复合薄膜具有更低摩擦系数；油环境下Stribeck曲线表明固体润滑复合薄膜在边界润滑阶段具有更低的摩擦磨损性能；高温环境下，随着温度升高，复合薄膜摩擦系数降低，其原因在于高温促进非晶碳的石墨化与MoS2的晶化。过高温度会促进MoS2的氧化而加剧薄膜失效。