【作者】 宋建荣；

【导师】 张联盟； Julie M.Schoenung；

【作者基本信息】 武汉理工大学 ， 材料加工工程， 2010， 博士

【摘要】 热障涂层是一类用于隔热、抗氧化、抗腐蚀的功能材料,它们能有效地保护在高温等恶劣环境下工作的部件。近年来,随着航天航空领域的飞速发展,对热障涂层的性能提出了越来越高的要求。因此,研制性能优异的新型热障涂层系统,开发先进的涂层制备新技术是当今材料科学领域的研究重点之一。为此,本文以7YSZ/Al2O3/Ni-343(7YSZ:ZrO2-7wt.%Y2O3; Ni-343:Ni22Cr10Al1Y)纳米涂层的同步合成和性能分析为目标,采用放电等离子烧结(Spark Plasma Sintering, SPS)技术为手段,通过对涂层的结构及其制备工艺的控制,成功地制备出具有纳米结构的7YSZ/Al2O3/Ni-343热障涂层,并对其各项性能进行了系统研究。以纳米7YSZ粉末、纯A1薄膜和预先低温球磨得到的纳米Ni-343合金粉末为原料,采用放电等离子烧结技术,在不同烧结温度、轴向压力、保温时间条件下制备出了不同结构的7YSZ/Al2O3/Ni-343热障涂层。研究了低温球磨对Ni-343粉体显微结构的影响,以及放电等离子烧结工艺与热障涂层组织、结构和性能之间的关系；对比了含有纳米和微米Ni-343粘结层热障涂层的结合强度、抗氧化行为和抗热冲击性能；并通过对Ni-343合金块体试样的进一步研究,确立了Ni-343合金微观结构、物相组成与力学性能的相互依赖关系,集中分析了纳米化对Ni-343合金以及热障涂层系统显微结构和性能的综合影响。实验结果表明,低温球磨技术可以有效地减小Ni-343粉体的晶粒尺寸至20-70nm。采用放电等离子烧结技术可以同步获得结构均匀、结合紧密、高温性能优异的纳米7YSZ/Al2O3/Ni-343热障涂层,其最佳制备参数为：7YSZ陶瓷层厚度500μm,Ni-343粘结层厚度150μm；烧结温度1000℃,轴向压力50MPa,保温时间3mmin。与微米涂层相比,含有纳米Ni-343粘结层的热障涂层具有更好的层间结合强度、抗氧化性能、以及较长的抗热冲击循环寿命。显微结构研究表明：热障涂层性能的提高与界面生成的Al2O3热生长氧化层(TGO)的结构、形貌密切相关。对Ni-343合金的研究发现,纳米Ni-343合金具有较高的显微硬度,并且其微观结构与力学性能在高温下比较稳定。本研究结果表明：采用放电等离子烧结技术可以在短时间内同步合成结构复杂的多层热障涂层,得到综合性能优异的热障涂层材料。这对于发展先进热障涂层的制备工艺具有积极的实际意义和良好的应用前景。更多还原

【Abstract】 Thermal barrier coatings (TBCs) have been widely used for protecting the superalloys from high temperature, oxidation and corrosion. The increasing demands for high performance superalloys in the turbine engines make TBCs a key component in combating degradation resulting from failure mechanisms. Therefore, high quality TBCs and advance fabrication process have been one of the important corners of materials science. In this study, multiple-layer TBC system was simultaneously synthesized on Ni superalloy substrate by spark plasma sintering (SPS) process, and the best parameters in SPS for high performance TBC were established.Nano-structured 7YSZ/Al2O3/Ni-343 multiple-layer TBCs with various microstructure were produced by SPS from nano ZrO2-7wt.%Y2O3 (7YSZ) powder, Al foil and nano Ni-343 powder made by cryomilling method. Afterwards, the mechanical properties arid high temperature behavior of 7YSZ/Al2O3/Ni-343 TBC and Ni-343 bulk sample were studied by advance testing techniques.The results indicated that, the grain size of Ni-343 powder was efficiently reduced to 20-70 nm by cryomilling method, and the microstructure and performance of TBCs were improved by SPS process. The best fabricating parameters were established as:a 500μm thick 7YSZ top coat, a 150μm thick Ni-343 bond coat, sintering at 1000℃, pressing under 50MPa axial pressure and dwelling for 3min at sintering temperature. Compared with conventional TBC, the performance of nano-structured TBC, such as bonding strength, oxidation-resistant behavior and thermal cycling life, was significantly improved by excellent microstructure between 7YSZ top coat and Ni superalloy substrate. The thermally growth oxide (TGO) in nano-structured TBC grew slowly and homogeneously, which enhanced high temperature performance of the TBC system.The research on Ni-343 alloy indicated Nano-structured fully dense Ni-343 bulk sample was strengthened by the mechanism of fine grain strengthen. The microhardness of Ni-343 bulk sample was influenced by microstructure and phase composition which determined by heat treatment conditions. In this dissertation, a novel technique for preparation of TBCs has been introduced, which characterized as simultaneous synthesis of a multiple-layer structure in simple process. The results from this research should be great helpful to the development of TBCs.更多还原