微晶玻璃二硫化钼薄膜的构筑及其空间摩擦学性能研究

In this project, the glass ceramics idea will be introduced into the microstructure design of MoS2 films. Firstly, the growth mechanism of unbalanced-magnetron-sputtered MoS2 films will be systemically investigated and clarified according to the theory of nonequilibrium thermodynamics and dynamics to fulfill the film amorphization. Secondly, the amorphous MoS2 film will be heat-treated in vacuum environment. In the vacuum heat-treatment process, the influences of temperature, holding time and temperature change rate in the crystallization of amorphous MoS2 films will investigated emphatically to fully understand the change mechanism from amorphous structure to nanocrystalline, to master the ratio and distribution of amorphous and crystallite phases in the films, and thereby to build a desired glass-ceramics-microstructure, in which the MoS2 nanocrystallites embed into the amorphous matrix of MoS2. Thirdly, the mechanical properties of glass-ceramics-microstructured MoS2 films and the friction/wear behavior in vacuum and thermal cycle conditions will be investigated to build the correlation among the microstructural, mechanical and tribological properties, to clarify the friction and wear mechanisms in simulated space environment, to fulfill the unification of low friction, low wear and low friction noise in the MoS2 film, and to provide the technical storage and support for the future development of space technology, especially for some moving parts that need high-precision, low-energy and high-stability in deep space exploration missions.

本项目将微晶玻璃结构引入二硫化钼（MoS2）薄膜的设计，研究非平衡磁控溅射MoS2薄膜在真空沉积和随后的真空热处理两个阶段的生长特性，从薄膜生长热力学和动力学角度探讨MoS2薄膜在真空沉积这一非平衡态生长过程中的非晶化机制，从平衡态生长理论阐明非晶态MoS2薄膜在真空热处理过程中的形核和晶体生长机制，揭示薄膜中非晶相、晶相的构成、比例和排布特点的变化规律及其与力学性能间的关系；通过模拟空间环境条件下（真空、高低温交变等）薄膜的摩擦磨损行为研究，揭示其摩擦学性能随空间环境因素的变化规律和润滑机制，实现具有非晶/纳米晶结构的高强度微晶玻璃MoS2薄膜的构筑，赋予MoS2薄膜低摩擦、低摩擦噪声和低磨损的有效统一，为我国未来某些型号任务中，运动部件对低能耗、高稳定性润滑材料的极致要求提供技术储备。

针对空间机械运动部件对低摩擦、低磨损以及高稳定性润滑薄膜材料的需求，开展了二硫化钼（MoS2）基薄膜材料的研究。采用封闭场非平衡磁控溅射技术结合真空热处理，通过工艺参数调节成功获得了微晶玻璃结构MoS2薄膜。对薄膜的结构演变规律及摩擦磨损性能进行了研究。结果表明，真空热处理导致薄膜内晶体的生长以及组织结构的变化，引起薄膜结构致密化。非晶基体中镶嵌的微晶尺寸在200°C热处理为3–8nm，400°C热处理后微晶尺寸增加到约10 nm或更大。当真空热处理温度为200°C时，薄膜的摩擦学性能明显改善。进一步对溅射MoS2薄膜进行了水浴热处理，水浴能诱导MoS2薄膜的应力发生变化并最终释放部分应变能，导致薄膜生长出新的细小的枝状晶结构，应变能同时还引起了薄膜中部分非晶结构组织向微晶结构转化以及2H-MoS2相向1T-MoS2相的转化。MoS2薄膜经特定条件的水浴处理后，薄膜致密性增加和晶粒尺寸缩小导致真空耐磨寿命得到了明显的改善。在此基础上，针对MoS2的悬键，创新性的提出了溅射结合液相合成在MoS2棱面悬键上原位生成纳米颗粒，进而制备出了MoS2-Au、MoS2-Cu2O、MoS2-Cr3O4、MoS2-Fe2O3等新型的MoS2-纳米颗粒复合薄膜，钝化悬键从而大幅度提高其耐环境和摩擦磨损性能。研究结果进一步深化了对MoS2薄膜结构变化规律的认知，提出了设计制备高性能薄膜的新思路和方法，为工程应用提供了技术储备。