核-壳/超声协同调控激光熔覆自润滑涂层界面及其对摩擦学行为影响机制

In order to solve the failure of lubricant oil and grease at elevated temperature and meet the need of structural-functional integration for key parts in advanced equipment, laser cladding self-lubricating nanocomposite coatings is one of the effective solutions. However, the key scientific problems are how to control interface reaction and broke nanocluster of nano/submicron lubricants. In order to solve the problems, in this research, electroplated Cobalt layer onto the surface of WS2/hBN solid lubricants particles for formation core-shell structure and high-energy ultrasonic vibration for broken nanocluster will be employed for interface manipulation of laser cladding self-lubricating nanocomposite coatings. Based on the result of the previous studies, the compatibilities, thermodynamics and dynamics of laser-clad precursor system before and after electroplating are firstly studied so as to reveal the influence on wetting force of melt/solid lubricants at the solid/liquid interface by electroplating Cobalt layer onto lubricants particles surface. Explore the laser ultrasonic hybrid cladding process for controlling interface reaction and broken nanocluster of nano/submicron lubricants. By thermal simulated test, the definite relationship among laser cladding process, interfacial behavior and microstructural morphology will be clarified. Finally, the mapping relationship of laser ultrasonic hybrid cladding process, interface behavior of core-shell structure nano/submicron lubricants particles and high temperature tribological properties of the self-lubricating coatings will be build..The results of this applied basic subject research are expected to provide scientific basis and technical support for solution the high temperature lubricating and wear problems of key parts in advanced technical fields.

激光熔覆纳米自润滑涂层为高温苛刻环境下润滑油脂失效及零部件“结构—功能”一体化提供了有效的解决方案。但研究发现控制熔池内微纳固体润滑颗粒界面反应及破解其团簇是决定该技术的关键科学问题。本项目基于核-壳结构有效控制界面反应进程以及高能超声破解微纳颗粒团簇并促进润湿的耦合效应，提出核-壳/超声协同调控激光熔池内复合WS2/hBN润滑体颗粒行为的新思路。采用微纳颗粒表面镀Co包覆的方法获得核-壳结构润滑体，研究核-壳结构对熔池内钴基合金熔体/润滑体界面润湿驱动力的影响机制；探索超声场破解核-壳结构微纳润滑体颗粒团簇所需工艺，阐明核-壳结构/超声场协同作用下颗粒再分布的特征及熔体/润滑颗粒间的作用规律；构建超声场辅助激光熔覆工艺—核壳结构微粒界面行为—摩擦学性能的关系，揭示其对涂层高温摩擦学行为影响机制。研究结果为激光熔覆熔体/颗粒界面控制及解决极端苛刻环境下的摩擦与润滑问题提供科学依据。

高温、高速、高真空、强氧化等苛刻环境下工作的航空航天、冶金、化工、热核等工业机械装备的关键基础件，其摩擦、磨损及润滑问题直接影响装备运行的稳定性与安全可靠性，也是目前制约我国许多高端技术领域关键装备发展的技术瓶颈之一。针对极端苛刻条件下，润滑油脂容易干燥、蒸发、分解或固化等失效难题以及关键零部件“结构—功能”一体化的需要，采用激光熔覆技术在关键基础件表面制备具有自润滑功能的纳米复合材料涂层，为上述问题提供了极其有效的解决方案。然而，控制熔池内微纳固体润滑颗粒界面反应及破解其团簇是决定该技术的关键科学问题。本项目基于核-壳结构有效控制界面反应进程以及振动破解微纳颗粒团簇并促进润湿的耦合效应，提出核-壳/超声协同调控激光熔池内复合润滑体颗粒行为的思路。采用微纳颗粒表面镀金属包覆的方法获得核-壳结构润滑体，研究核-壳结构对熔池内钴基合金熔体/润滑体界面润湿驱动力的影响机制；探索振动场破解核-壳结构微纳润滑体颗粒团簇所需工艺，研究了核-壳结构/超声场协同作用下颗粒再分布的特征及熔体/润滑颗粒间的作用规律；建立超声场辅助激光熔覆工艺—核壳结构微粒界面行为—摩擦学性能的关系，揭示其对涂层摩擦学行为影响机制。研究结果表明，最佳施镀条件下的镀镍纳米WS2复合粉末不含杂质相，镍以纳米级状态存在且与WS2颗粒包覆紧密。在热力学分析的基础上，借助模拟试验法，研究了钴基合金/Nano-WS2/LaF3·CeF3体系中界面反应机理，WS2和LaF3·CeF3在熔池内发生了部分分解，MoS2与LaF3·CeF3分解后的Mo、S、La、Ce元素又与Co形成了新相。超声微振辅助激光熔覆工艺能够改善复合涂层的成形质量，制备出的复合涂层表面平滑，内部组织致密、无宏观裂纹和孔洞等缺陷；且能够改善自润滑复合涂层摩擦学性能，使涂层摩擦系数在磨损过程中更加平稳，磨损后的表面更加平滑。研究结果为激光熔覆熔体/颗粒界面控制及解决极端苛刻环境下的摩擦与润滑问题提供科学依据。