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的耐用、高温材料的选择，例如喷气发动机涡轮叶片的涂层，但水蒸气可以意外地改变陶瓷的性能。例如，在高温下，当陶瓷可以软化时，当存在高压水蒸气时，它可能更容易变形。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，造成不均匀的结构和可能发生故障的薄弱环节。这些变化的机制目前还不清楚。这项研究确定了哪些陶瓷材料在暴露在高温水蒸气中时最容易改变性能，并研究了水蒸气可以改善或降解陶瓷的条件。技术细节：该项目通过研究高温下暴露于水蒸气中氧化物中的晶界扩散是否显著影响这一现象的严重性。这项探索性研究对于理解固体氧化物在高温下暴露在水蒸气中的后果非常重要，因为陶瓷被推动用于更苛刻和更高温度的环境，并被设计成越来越小的尺寸。测量在水蒸气存在下的烧结、蠕变和偏析变化的研究被用来确定是否增强了晶界扩散。结合质子对晶界扩散的作用也被认为是一种可能的机制。这项研究确定了高温下在水蒸气中使用氧化物陶瓷是否有必要制定缓解措施，以及水蒸气强化烧结作为一种低能量途径是否可行。学生接受培训，学习先进的分析技术，包括尖端的电子显微镜和光谱技术。

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.