热循环条件下金属/氮化物多层涂层异质界面稳定性控制及其对氧化行为影响研究

Due to favorable mechanical properties, Ti/TiAlN multilayer coating is considered as a potential protective coating for titanium alloy compressor. However, under medium high temperature, heterogeneous interfaces of Ti/TiAlN multilayer coating become unstable and sublayers react with each other. The absence of metal layers and formation of ceramic phases lead to stress accommodation, which further induces cracking and eventually deteriorates oxidation resistance. According to Nitrogen-Potential Diagram, substitution of Ti layers by Cr and subsequent constituting of Cr/TiAlN multilayer coatings can avoid the reactions between Cr and TiAlN sublayers, so that it can maintain the thermal stability of sublayer interfaces. In this case, Cr layers can accommodate and relieve stress, thus reducing or eliminating the risk of cracking in the multilayer coating. Furthermore, Cr layers exhibit excellent oxidation resistance. Nevertheless, mechanisms on stability of heterogeneous interfaces in Cr/TiAlN multilayer coating and its effect on oxidation behavior have not been clarified. In this project, the designing concept of anti-oxidation resistance under medium high temperature of Cr/TiAlN multilayer coating with stable sublayer interfaces will be proposed. The micro-mechanism researches on stability of heterogeneous interfaces and its effect on oxidation behavior of coating-substrate system will be carried out under thermal cycling. Effects of microstructure and mechanical properties on interface optimization and service failure mechanism will be investigated. Based on these studies, the controllable designing principle of multilayer coatings with thermal stable heterogeneous interfaces will be acquired. Eventually, expected research results will enrich the knowledge of metal/nitride multilayer coatings and provide theory guidelines to their applications.

Ti/TiAlN多层涂层具有优良的力学性能，是潜在的钛合金压气机防护涂层。然而，在中高温下该涂层异质界面失稳，层间发生反应，金属层的缺失和陶瓷相的形成造成应力累积，引起开裂，最终降低涂层的抗氧化性。由金属氮势图可知，采用Cr替换Ti层构筑Cr/TiAlN多层涂层可避免子层反应，以保持界面的热稳定性：Cr层容纳吸收应力，降低或消除多层涂层因应力累积而开裂的风险，且Cr层具有良好的抗氧化性。Cr/TiAlN多层涂层异质界面稳定性及其对氧化行为的影响机理尚不明确。基于此，本项目提出子层界面稳定且具有抗中高温氧化性能的Cr/TiAlN多层涂层设计思想，开展热循环条件下异质界面稳定性的微观机制及其对膜基体系氧化行为影响机理研究，考察微观组织结构及力学特性对界面优化规律及服役失效机理的影响，提出异质界面热稳定的多层膜可控设计原则。预期研究成果将丰富金属/氮化物多层涂层的认知，为其应用提供理论指导。

金属/金属氮化物多层涂层因具有优良的力学性能和高温防护性能，可成为潜在的钛合金压气机防护涂层。但是，不合理的结构设计可能会引起服役性能的变化，例如，在中高温下一些金属子层和氮化物子层的异质界面失稳，层间发生反应，金属层的缺失和陶瓷相的形成造成应力累积，引起开裂，最终降低涂层的抗氧化性。由金属氮势图可知，采用Cr替换Ti层构筑Cr/TiAlN多层涂层可避免子层反应，以保持界面的热稳定性：Cr层容纳吸收应力，降低或消除多层涂层因应力累积而开裂的风险，且Cr层具有良好的抗氧化性。Cr/TiAlN多层涂层异质界面稳定性及其对氧化行为的影响机理尚不清楚。基于此，本项目提出了子层界面稳定且具有抗中高温氧化性能的Cr/TiAlN多层涂层设计思想，开展了热循环条件下异质界面稳定性的微观机制及其对膜基体系氧化行为影响机理研究，对比了不同子层搭配的Ti/TiN、Ti/TiAlN及Cr/TiAlN多层涂层的高温防护性能表现，考察了氮化物层（TiN及TiAlN）和金属层（Ni-Al和Ti-Al）微观组织结构及力学特性对界面优化规律及为钛合金高温服役失效机理的影响，具体研究了单层氮化物涂层及多层涂层的抗高温氧化和腐蚀性能，并由此提出了异质界面热稳定的多层膜可控设计原则。本项目的顺利开展，阐明了子层界面热稳定性和涂层-基体的氧化行为与元素迁移、界面阻扩散及约束塑性变形/相变行为的微观作用机制，实现了异质界面热稳定的金属/氮化物多层膜可控设计，探明了影响单层、多层涂层抗热腐蚀性的作用机制。.本项目的研究成果丰富了钛合金高温防护涂层的选择，发展了防护涂层抗热腐蚀性理论，完善了金属/金属氮化物多层涂层的认知，发表了高水平SCI5篇，授权了发明专利5项，其中第一发明人4项，出版了专著1部。