基于元素热扩散效应的宽温域多循环强韧化自润滑薄膜设计及相关机理研究

Self-lubricating films at wide temperature range have the problems of continuous lubrication degradation over multi-thermal-cycle and mechanical properties deterioration caused by the added lubricating phases. Based on the thermal diffusion of the metal elements in the transition layer of oxide films during annealing, this proposal take advantage of the diffusion behavior of the metal elements to improve the strength and toughness of the films. Meanwhile, a bimetallic oxide lubricant is formed in-situ on film surface through the regulation of oxidation behavior of the diffusion elements. The strengthened and toughened self-lubricating films at wide temperature range over multi-thermal-cycle can be further developed. The effects of the film microstructure, transition layer composition, annealing processes and their interaction on the diffusion and oxidation behaviors of the metal elements are studied in detail. The diffusion mechanism of the metal elements in the film and the oxidation mechanism of metal elements on the film surface will be revealed. The effects of diffusion and oxidation of the metal elements on the mechanical and the tribological properties at wide temperature range over multi- thermal-cycle will be investigated. The structural regulation criteria for in-situ formation of bimetallic oxide lubricants at high temperature by metal elements diffusion will be established.The strengthening and toughening mechanisms of elements diffusion will be further clarified as well as the continuous lubrication and wear mechanisms of the film at wide temperature range over multi-thermal-cycle. The design principles, regulative basis and key preparation techniques of the strengthened and toughened self-lubricating film at wide temperature range over multi-thermal-cycle will be proposed. This proposal will propose the new ideas and methods for the design of strengthened and toughened self-lubricating materials at wide temperature range over multi-thermal-cycle, and has important theoretical significance to promote the practical application of the materials in high-tech fields.

针对宽温域自润滑薄膜材料在多温度循环下的持续润滑及强韧化设计难点，本项目提出基于氧化物薄膜退火处理过程中过渡层金属元素的热扩散效应，提高薄膜的强度和韧性，并通过扩散元素在薄膜表面的氧化行为调控，高温原位生成双金属氧化物润滑相，进而设计制备宽温域多循环强韧化自润滑薄膜。深入研究薄膜微观结构、过渡层组分、退火处理工艺及其之间的交互作用对元素扩散-氧化行为的影响，探明退火处理过程中元素的扩散-氧化机制；研究元素的扩散-氧化行为对薄膜力学及宽温域多循环摩擦学性能的影响，建立扩散元素高温原位自生双金属氧化物润滑相的结构调控准则，揭示薄膜的强韧化机制及在宽温域多循环下的持续润滑和磨损机理，提出宽温域多循环强韧化自润滑薄膜的设计构筑原则和调控依据，并形成关键制备技术。本项目的实施对于提出宽温域多循环强韧化自润滑材料设计新思路和新原理，推动其在高技术领域应用具有重要的理论意义。

以航空发动机为代表的高温机械对宽温域自润滑材料提出了迫切需求，然而传统宽温域自润滑材料经历高温后的组织结构变化使得力学与摩擦学性能恶化，因此宽温域循环工况下组织结构稳定性成为宽温域自润滑材料的设计难点。本项目基于金属元素的热扩散效应，通过高温热处理在氧化物薄膜表面构筑宽温域氧化物润滑相，在保障力学性能的同时赋予其宽温域循环润滑性能。通过研究基材组织演变对基材表面物相结构的影响，揭示基材金属元素在热处理过程中的扩散机制。通过共沉积方法在Cr-Cr2O3过渡层中引入Ti元素，探究了过渡层中金属元素的扩散对薄膜组织结构的影响，揭示过渡层中金属元素在Cr2O3薄膜中的扩散机理。通过薄膜组织结构及热处理工艺调控，在Cr2O3薄膜表面原位形成CrTiO3润滑相，赋予薄膜优异的宽温域摩擦学性能，阐明了CrTiO3在宽温域环境下的润滑机理，并提出了宽温域自润滑薄膜的设计构筑原则和调控依据。