高温自润滑涂层微观组织优化与性能调控机制研究

A self-lubricant coating is one of the most important hotspots in the thermal spraying regions, any which the microstructure-properties relationship should be enucleated, firstly. However, the performance of thermal sprayed coatings is non-linearly coupled with microstructure existing in composite coatings. Moreover, at the micro-scale, self-similar is an important basic feature for thermal sprayed self-lubricant coatings, which can affect the coatings performance in some extent. In this task, in order to obtain the depositing feature of NiCr-WSe2-BN-Y agglomerate particle, a multi-scale model was built. Then, as a sample, the nanometer NiCr-WSe2-BN-Y coatings were fabricated by Plasma Spraying. Where, some microstructures affected the lubricant properties of coatings, such as particle shape, pores, and particle phases and coatings thickness were extracted with wavelet. Lastly, the relationship between deposited particle, microstructure and performance of thermal sprayed composite coatings has been established. This can provides a theoretical and technical foundation of lubricant coating fabrication and characterization for the friction surface of weapon equipment.

高温自润滑涂层是摩擦领域研究的热点之一，结合涂层的生长机制研究涂层减摩自润滑损耗机理成为其基础的科学问题。本课题以等离子喷涂制备的 NiCr-WSe2-BN-Y复合减摩自润滑涂层为样本，从涂层微观构建机制出发，采用基于面向微观结构建立随机逾渗模型，建立团聚颗粒的特征参数、涂层微观结构以及涂层减摩自润滑性能之间的多尺度关联。以期阐述高温自润滑涂层微观结构与减摩自润滑性能关联的科学规律，为高性能减摩自润滑涂层的制备与微观组织优化提供理论基础和技术支撑。

高性能宽温域固体自润滑涂层一直是摩擦学领域研究的热点。本项目主要围绕NiCr基高温自润滑涂层的生长机制与性能调控展开研究，设计了含WSe2、hBN两类固体自润滑涂层，优化形成了该类涂层的制备工艺。摩擦学试验结果显示，优化工艺后制备的涂层在30℃~800℃中的摩擦系数不大于0.299。对此，课题主要展开以下研究：(1)NiCr-BaF2-CaF2-WSe2-Y(hBN)自润滑涂层静态高温氧化特性和宽温域自润滑机理。结果显示，静态高温氧化时涂层表面会生成针状晶体氧化物，涂层在800℃摩擦环境中产生的薄膜中以(CrO4)-2与(NiF6)-2为主与涂层中的金属离子形成釉质盐类化合物，在宽温域下起自润滑作用；当涂层中不含Cr时，高温状态下以(BO3)-3和(NiF6)-2与金属离子产生氧化物釉层为主的协同自润滑。(2)探索了等离子沉积NiCr高温自润滑涂层组织优化模型。采用小波分形维数对固体自润滑涂层微观组织形貌进行分形表征，获得了涂层微观结构的多重分形谱，为涂层的优化评估提供了判定方法。(3)针对涂层微观结构与性能之间的跨尺度问题，基于固体自润滑涂层微观结构建立了非均匀有限元模型，结果显示，复相涂层各相的界面在接触应力作用下会产生应力集中，是裂纹产生的根源。(4)结合课题研究背景，提出通过表征涂层抗高温熔滴粘蚀能力来量化涂层耐粘蚀性能的检测方式，完善了固体自润滑涂层应用评价手段。通过系统研究两类润滑涂层的微观结构与性能之间的关系规律，建立了涂层微观结构特征与摩擦磨损性能之间的模型，形成了粘蚀物清理装置，为固体自润滑涂层的制备与应用提供了理论和技术支持。