CAREER: Designing Ceramic Microstructures by Controlling Anisotropic Grain Boundary Motion

University Of Florida, Gainesville FL

Investigators

Abstract

NON-TECHNICAL SUMMARY Ceramic materials are used in a variety of high-tech applications, spanning from airplane engines to microprocessors. Many ceramics are composed of microscopic features known as grains. The size of these grains dictates many material properties, including crack resistance. A significant challenge to fabricating reliable ceramic parts is the ability to control the grain size, because grains grow unpredictably at the high temperatures needed for processing. The goal of this work is to uncover the underlying mechanism for grain growth in ceramic materials to guide new processing methods for optimal performance. To accomplish this goal, this program trains the next generation of ceramic engineers in the necessary skills for advanced material processing. Additionally, this program’s educational goal is to build a creative and multi-disciplinary workforce by engaging pre-collegiate art students in activities that demonstrate the similarities between artistic and scientific processes. To support this effort, a ceramic-processing kit is being developed and implemented in K-12 schools. TECHNICAL SUMMARY The goal of this CAREER program is to establish a mechanistic approach that leverages anisotropic grain boundary motion to advance microstructure design. Discontinuous changes in mobility due to grain boundary restructuring have been hypothesized as the cause of irregular grain growth in ceramics. However, this restructuring involves a change in energy, conflating the thermodynamic and kinetic contributions to grain boundary motion. Without this insight into grain boundary motion mechanisms, processing optimization relies on heuristic, inefficient testing, which inhibits microstructure designs. The experimental approach in this CAREER program unambiguously deconvolutes the thermodynamic and kinetic contributions of grain boundary motion by measuring the mobility of flat grain boundaries with a controlled driving force: energy from an applied magnetic field. The impact of this anisotropic mobility on microstructure evolution is elucidated through grain growth studies using new, non-destructive x-ray diffraction microscopy. With this mechanistic-insight, a new processing framework can be designed for modifying grain boundaries to design microstructures with advanced performance. The development of a creative, multi-disciplinary workforce is critical to implementing such a processing-framework. Therefore, this program encompasses an educational plan that combines artistic and scientific methodologies in precollegiate activities, including developing and implementing a multidisciplinary ceramic kit for distribution in K-12 schools. Additionally, engineering students are trained in ceramic processing and characterization skills necessary to advance materials processing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.