CAREER: High Temperature Deformation of Stand-Alone Plasma-Sprayed Yttria-doped Zirconia Coatings

在典型的使用温度（800℃-1400℃）下，对等离子喷涂的7 wt.% Y2O3-ZrO2 （YSZ）热障涂层进行了广泛的研究，并对独立涂层进行了改进的压缩试验。在测试中，将YSZ涂层从基体上去除以隔离其行为，并进行蠕变测试，应力松弛和快速断裂实验。除了机械测试外，我们将使用以下表征方法进行拟议的工作：膨胀测量法，透射电子显微镜，x射线衍射，拉曼光谱和激光闪光（测量导热性）。列出的每种方法将提供必要的信息来解释机械测试结果。因此，本研究的主要成果将是模拟操作环境中等离子喷涂YSZ的结构-性能关系。这将涉及建立变形机制作为温度、应力、时间和样品微观结构（即孔隙率和片层尺寸）的函数。该项目还将通过课程开发、推广和指导，为终身的卓越教育奠定基础。为了增加非专业学生对普渡大学材料课程的参与，将设计基于网络的模块，将材料科学应用与每个工程专业直接联系起来，然后将其纳入介绍性材料课程。除了普渡大学的活动之外，还将在印第安纳州拉斐特的杰斐逊高中（Jefferson High School， JHS）为理科生设立一个推广项目。在这个项目中，高三学生将在暑期与我们的研究小组一起度过8周的时间，然后在高三的秋季和春季通过JHS建立的研究型科学课程继续他们的研究。在计划的工作中，还将有一个重要的本科生指导部分，通过每年秋季和春季学期的普渡大学MSE本科生的支持，以及每年夏天的本科生研究经验（REU）学生的支持。如今，几乎所有商用和军用飞机都使用热障涂层（tbc）来保护其燃气涡轮发动机的金属结构免受极端温度的影响，或者允许发动机在更高、更有效的温度下运行。除了运输部门，能源部门也依赖于tbc在发电时提供的工业燃气轮机（IGTs）的效率提升。虽然tbc的好处在这些部门和其他部门节省了大量成本，但我们仍然不了解tbc的许多方面。例如，在高温工作期间，它们经常收缩、开裂甚至与底层金属结构分离。因此，对其高温机械性能的基础研究将使我们能够充分利用使用这些涂层的好处。因此，在最基本的层面上，该提案侧重于确定控制tbc在服役时“工作”的材料特性，并将作为设计下一代tbc的基础。

Thermal barrier coatings of plasma-sprayed 7 wt.% Y2O3-ZrO2 (YSZ) are to be extensively studied at representative use temperatures (800 degrees C-1400 degrees C) using a modified compression test for stand-alone coatings. For the test, the YSZ coating is removed from the substrate to isolate its behavior, and creep testing, stress relaxation, and fast fracture experiments will be performed. In addition to mechanical testing, we will use the following characterization methods for the proposed work: dilatometry, transmission electron microscopy, X-ray diffraction, Raman Spectroscopy, and laser flash (to measure thermal conductivity). Each method listed will provide the necessary information to interpret the mechanical testing results. Thus, the principal output of this research will be structure-property relationships of plasma-sprayed YSZ in simulated operating environments. This will involve establishing deformation mechanisms as a function of temperature, stress, time, and sample microstructure (i.e. porosity and lamella size). This program will also establish a foundation for a lifetime of educational excellence through curriculum development, outreach, and mentoring. To increase non-majors participation in materials classes at Purdue, web-based modules will be designed that directly relate materials science applications to each of the engineering majors, and then incorporated into the introductory materials course. Beyond the activities at Purdue, an outreach program for science students at Jefferson High School (JHS) in Lafayette, Indiana will be established. In this program, high school juniors will spend 8 weeks of the summer with our research group, then continue their research in the fall and spring of their senior year through an established research based science class at JHS. There will also be a significant undergraduate mentoring component in the proposed work through support of a Purdue MSE undergraduate student every fall and spring semester of the program, as well as a Research Experience for Undergraduates (REU) student every summer.Virtually every commercial and military aircraft flying today uses thermal barrier coatings (TBCs) to protect the metallic structure of its gas turbine engine(s) from temperature extremes and/or to allow the engine to be operated at higher, more efficient temperatures. In addition to the transportation sector, the energy sector also relies on the efficiency boosts TBCs provide industrial gas turbines (IGTs) as they produce electricity. While the benefits of TBCs result in significant cost savings in these and other sectors, there are still many aspects of TBCs we don't understand. For example, they often shrink, crack and even detach from the underlying metallic structure during elevated temperature service. Thus, basic research into their high temperature mechanical properties will allow us to fully utilize the benefits of using these coatings. At its most fundamental level, then, this proposal focuses on determining the material properties that govern how well TBCs "work" while they are in service and will serve as a basis for designing next-generation TBCs.