热喷涂YSZ涂层内润滑剂的原位合成及其作用机理研究

Self-lubricating ceramic coatings with high reliability and long service life are very important to solve the friction, wear and lubrication problems of the mechanical components serving in extreme harsh conditions. However, traditional self-lubricating ceramic coatings have high brittleness, and their mechanical properties would be further degraded because of tribological design, which significantly reduces their service stability and crack resistance. In this application, several kinds of solid lubricants will be in-situ synthesized in the pores and microcracks of thermally sprayed YSZ coatings. Thermally sprayed ceramic coatings with excellent mechanical properties and outstanding friction performance can be further developed. The morphology, phase composition, element distribution and structure of worn surface under different sliding distances will be analyzed to clarify the formation mechanism and evolution of the lubrication films, thus revealing the mechanisms of lubrication and failure of the coatings. The influencing rule and mechanism of the types, contents, sizes and growth patterns of lubricants on the mechanical properties as well as friction and wear properties will be investigated and the new principle of lubrication and anti-wear as well as the new method of controlling friction and wear will be put forward. After the above studies, the relationship and mechanism among in-situ synthesized lubricants, mechanical properties, lubrication performance and wear life of the coatings will be revealed, which would provide a new idea for the design and preparation of thermally sprayed self-lubricating ceramic coatings.

高可靠、长寿命的陶瓷自润滑涂层对于解决机械零部件在极端苛刻服役环境下的摩擦、磨损和润滑问题具有十分重要的意义。然而传统陶瓷自润滑涂层由于其本征脆性和摩擦学设计所带来的力学性能下降，显著降低了其使用稳定性和抗裂纹破坏能力。本项目拟通过水热反应/热解反应,在热喷涂YSZ涂层孔隙和微裂纹等缺陷处原位合成低剪切力的固体润滑剂，探索并发展出兼具优异力学性能和摩擦学性能的热喷涂陶瓷涂层。通过对经过不同磨程后摩擦界面微观形貌、元素分布、物相组成及结构的分析，阐明润滑膜的形成机理和演变规律，揭示涂层的润滑机理和磨损失效机制；研究润滑相种类、含量、尺寸及生长方式对涂层力学性能和摩擦学性能的影响规律及作用机理，提出润滑抗磨的新原理及摩擦磨损调控的新方法。通过研究，揭示原位合成润滑剂与涂层力学性能、润滑性能及磨损寿命之间的相关性和作用机理，为热喷涂陶瓷自润滑涂层的设计与制备提供新思路。

热喷涂氧化物陶瓷涂层高可靠、长寿命的自润滑性能是新材料摩擦学研究热点，而涂层在摩擦中能自适应形成长效润滑膜是从根本上解决该问题的一个有效途径。然而，传统陶瓷自润滑涂层由于其本征脆性和摩擦学设计所带来的力学性能下降，显著降低了其使用稳定性和抗裂纹破坏能力。为解决上述问题，本研究通过水热反应，在热喷涂 YSZ 涂层固有的孔隙和微裂纹等缺陷处原位合成了系列具有低剪切力的固体润滑剂，并对其增韧补强机制与润滑机理进行了深入研究，具体地：1）合成了以非晶成分为主的碳润滑剂，并通过对反应温度的调控，优化了 YSZ-碳复合涂层的微观结构、力学性能和摩擦学性能。其中，相比于纯YSZ 涂层，YSZ-碳复合涂层的摩擦系数可以减少 77.1%，达到 0.22，比磨损率从 6.33×10-4 mm3 N-1 m-1 下降到 2.25×10-7 mm3 N-1 m-1；2）针对高端装备对更低摩擦系数、更高硬度和更高可靠性的陶瓷自润滑涂层的需求，在YSZ涂层缺陷内通过一步法合成了二硫化钼和碳的复合润滑剂，进一步提升了涂层的摩擦学性能。其中，相比于纯YSZ 涂层，YSZ-二硫化钼/碳复合涂层摩擦系数可以减少至 0.15，比磨损率降至 1.25×10-7mm3 N-1 m-1；3）研究了合成润滑剂的含量、尺寸及生长方式对涂层力学性能和摩擦学性能的影响规律；4）聚焦摩擦界面成分、结构和摩擦学性能的演变规律，从介观和微观尺度揭示了润滑机理和磨损失效机制。本研究提出了润滑抗磨的新原理及摩擦磨损控制的新方法，为热喷涂陶瓷自润滑涂层的设计与制备提供了新思路。