EAGER: The Role of Water Vapor and Incorporated Protons in Enhancing Diffusion and Sintering in Ceramics

非技术描述：陶瓷是许多技术应用中耐用的高温材料，例如喷气发动机涡轮叶片的涂层，但水蒸气会意想不到地改变陶瓷的性能。例如，当陶瓷在高温下可以软化时，当高压水蒸气存在时，它更容易变形。当在高温下引入水蒸气时，陶瓷中的不同元素可能会更快地分离，从而产生不均匀的结构和可能发生故障的薄弱点。这些变化的机制目前还不清楚。本研究确定了哪些陶瓷材料在暴露于高温水蒸气时最容易发生性能变化，并研究了水蒸气可以改善或降低陶瓷的条件。代表性不足的社区大学生和返回美国的退伍军人也参与了这个项目。技术细节：本项目通过研究这种现象的大小，研究氧化物中的晶界扩散是否受到高温下水蒸气暴露的显著影响。这项探索性研究对于理解高温下固体氧化物暴露于水蒸气的后果非常重要，因为陶瓷被要求在更恶劣和更高温度的环境中使用，并且设计的尺寸越来越小。研究测量在水蒸气存在下烧结、蠕变和偏析的变化，以确定晶界扩散是否增强。结合质子在晶界扩散中的作用也被评价为一种可能的机制。本研究确定了在高温水蒸气中使用氧化物陶瓷是否有必要开发缓解措施，以及水蒸气增强烧结作为低能量路线是否可行。培训学生学习先进的分析技术，包括尖端的电子显微镜和光谱学技术。

NON-TECHNICAL DESCRIPTION: Ceramics are the durable, high temperature material of choice for many technical applications, such as coatings for turbine blades in jet engines, but water vapor can unexpectedly change the properties of a ceramic. For example, at high temperatures when a ceramic can soften, it can be even easier to deform when high pressure water vapor is present. Different elements in a ceramic may segregate more rapidly when water vapor is introduced at high temperatures, creating a non-uniform structure and weak spots where failure can occur. The mechanism for these changes is not currently understood. This research identifies which ceramic materials are most susceptible to changing properties when exposed to high temperature water vapor, and studies the conditions for which water vapor can improve or degrade the ceramic. Underrepresented community college students and returning U.S. veterans are also participating on this project.TECHNICAL DETAILS: This project studies whether grain boundary diffusion in oxides is significantly affected by exposure to water vapor at high temperatures by studying the magnitude of this phenomenon. This exploratory research is important for understanding the consequences of exposure of solid oxides to water vapor at high temperatures, as ceramics are pushed to be used in harsher and higher temperature environments and designed with smaller and smaller dimensions. Studies measuring changes in sintering, creep and segregation in the presence of water vapor are used to determine if grain boundary diffusion is enhanced. The role of incorporated protons on grain boundary diffusion is also evaluated as a possible mechanism. This research determines if the development of mitigation measures is necessary for the use of oxide ceramics in water vapor at high temperatures and if water vapor enhanced sintering as a low energy route is feasible. Students are trained to learn advanced analytical techniques, included cutting-edge electron microscopy and spectroscopy techniques.