自适应氮化物基纳米结构复合涂层的热管理研究

In the dry friction, especially under the conditions of high-speed cutting, a sharp rise in the surface temperature of machine parts or tools happens, which easily leads to the failure of the coatings or substrate materials. Hence, it has important implications to research the contact thermal management of hard coatings for optimizing the composition and structure of the coating materials. In order to achieve self-regulatory function of thermal conductivity, heat distribution and thermal peak mitigation of the hard coatings at the service, the composition optimizing, the microstructure and phase changes and chemical reactions, etc. of the hard coatings have been investigated. The key research is the following: (1) To research the thermal conductivity properties of the coating in different temperatures by considering the composition, crystal structure, atomic, ionic radii and phonon scattering factors, and to explore the intrinsic link between above factors and thermal conductivity. (2) To research the thermal conductivity properties of the coatings when diffusion, chemical reaction, phase structure change happen at different temperatures especially under high temperature. (3) To research the effect of oxygen vacancies on the thermal conductivity of the coatings according to the theory of phonon scatterings, to research effect of oxide melting point and fusion latent heat on the mitigation of thermal peak. The project aims to optimize the composition of nanostructured composite coatings based on the concept of thermal management, to provide theoretical guidance for the design and preparation of nanostructured composite coatings which has an adaptive thermal management function.

在干摩擦特别是高速切削条件下，机器零件或工具的表面温度急剧上升，易造成涂层或基底的失效，因此研究涂层的接触热管理对于优化涂层材料的成分和结构都具有重要意义。本项目探索通过优化涂层的成分、利用微结构和相结构的变化和化学反应等，实现涂层在服役时的导热性、热流分配和热峰值缓解的自我调节功能。重点研究：（1）研究涂层在不同温度的导热性能，综合考虑成分、晶体结构、原子量、离子半径等与声子散射相关因素，探索其与涂层导热性能之间的内在联系。（2）研究不同温度特别是高温下涂层发生扩散、化学反应、相结构等变化对导热性能影响，探索其与导热性能之间的内在联系。（3）根据声子散射理论研究氧空位对涂层热导率的影响，探索在摩擦中复合氧化物的熔点和熔化潜热对热峰值缓解的作用。本项目旨在基于热管理的概念优化纳米结构复合涂层的成分组元和结构，为设计和制备具有热管理功能的自适应纳米结构复合涂层提供理论指导。

本研究以过渡族金属氮化物为对象，详细研究了氮化物薄膜晶粒尺寸、界面变化及晶格畸变等对热扩散率的影响。通过添加提升薄膜热稳定性能以及宽温域摩擦磨损性能的元素及控制工艺参数等方式制备在宽温域下均具有低摩擦系数和低磨损率的自润滑纳米结构复合薄膜。详细研究了如C、Al、Si、B、Ag、Cu等合金元素的添加对过渡族金属氮化物微观结构、力学以及宽温域摩擦磨损性能的影响。揭示了各添加元素在薄膜中的存在形式，研究了Al、Si及B元素提升薄膜热稳定性能的原因，讨论了C在室温下的自润滑作用机理，并在此基础上，通过添加Ag、Cu来进一步提升薄膜中、高温环境下的摩擦磨损性能，成功制备出了一系列的兼具优异力学、高温热稳定性能及宽温域自润滑性能的氮化物复合薄膜材料。解决了传统润滑薄膜使用温度窄的难题，为制备新型智能纳米结构薄膜提供理论指导和设计准则。