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

University Of California-Irvine, Irvine CA

Investigators

Abstract

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.