POWRE: Electron Microscopy Studies of the Microstructure and Chemistry of Interfaces in Thermal Barrier Coating Systems

本项目研究面层/热生长氧化物(TGO)/粘结层界面的微观结构、成分和结合方面，以了解和控制热障涂层的层裂问题。目标是开发一套材料和工艺建议，以生产一种具有更高可靠性和减少剥落倾向的TBC(热障涂层)系统。第二个目标是定制这种改进的TBC系统，以承受飞机涡轮机应用中的更高操作温度。电子显微镜将被用来研究氧化铝中存在的物相作为工艺条件和热循环的函数。我们的目标是将TBC加工过程中氧化铝层中发生的任何相变与层裂相关联。微量添加反应元素会导致不同氧化物的形成，这将通过探测粘结层中的晶界和TGO/粘结层界面上反应元素的偏析来作为粘结层化学的函数进行研究。利用超高压STEM中的超小探头提供的高分辨率成像和电子能量损失谱(EELS)相结合的方法来研究这种偏析问题。目标是使用从EELS获得的结合信息来确定其他氧化物的存在对TGO/粘结层界面强度的影响。%这是根据妇女在研究和教育中的职业机会(POWRE)计划提供的研究增强补助金。这项研究将有助于提供与用于飞机涡轮机的热障涂层相关的基础材料科学知识。该项目通过研究生直接参与与课堂活动相关的研究，鼓励研究与教育相结合。该项目由材料研究司和MPS OMA(多学科活动办公室)共同支持。***

This project investigates the microstructural, compositional, and bonding aspects of the topcoat/thermally grown oxide(TGO)/bondcoat interfaces to understand and control the spallation problem of thermal barrier coatings. The goal is to develop a set of materials and processing recommendations which will produce a TBC(thermal barrier coating) system with improved reliability and a reduced propensity for spallation. A secondary goal is to tailor this improved TBC system to withstand higher operating temperatures in aircraft turbine applications. Electron microscopy(TEM) will be used to examine the phases present in alumina as a function of processing conditions and thermal cycling. The objective is to correlate any phase transitions that occur in the alumina layer during TBC processing to spallation. Trace additions of reactive elements can lead to the formation of different oxides, and this will be investigated as a function of bondcoat chemistry by probing grain boundaries in the bondcoat layer and the TGO/ bondcoat interface for the segregation of reactive elements. A combination of high resolution imaging and electron energy loss spectroscopy (EELS) provided by an ultrasmall probe in a UHV STEM will be used to study this segregation issue. The goal is to use bonding information obtained from EELS to determine the effect of the presence of other oxides on the strength of the TGO/bondcoat interface.%%% This is a research enhancement grant made under the Professional Opportunities for Women in Research and Education (POWRE) program. The research will contribute basic materials science knowledge relevant to thermal barrier coatings used in aircraft turbines. The project encourages the integration of research and education through direct graduate student participation in research related to classroom activities. The project is co-supported by the Division of Materials Research, and the MPS OMA(Office of Multidisciplinary Activities). ***