Date of Award
Doctor of Philosophy (PhD)
School of Materials Science and Engineering
Ceramic microspheres, especially the cerium-based and uranium-based ceramic microspheres, are highly demanded in different applications due to their chemistry and the unique microstructures. The dense microspheres are critically important for nuclear rocket fuels and high-temperature gas cool reactor fuels. The porous microspheres are widely used in thermochemical reactions for carbon dioxide splitting. The existing ceramic microspheres fabrication processes have many challenges, such as unfavorable chemistry, complex steps, and inhomogeneous composition distribution. Those problems have motivated a new method to validate an alternative technique. The sol-gel process with polymer additives designed and constructed in this study is capable and successful of producing homogeneous chemistry and desired microstructures of cerium- and uranium-based ceramic microspheres. Herein, this dissertation is focused on fundamentally understanding and studying sol-gel process with polymer additives based routes towards the fabrication of cerium-based and uranium-based ceramic microspheres with desired microstructures. The topics cover the fabrication and properties of ceramic microspheres, controlling the chemical composition and phase evolution, combining sol-gel process and polymerization technology, and their applications. To start with, the first chapter talks about the current research and challenges in developing ceramic microspheres, their potential applications, and the challenges of the sol-gel process towards ceramic microsphere fabrication. In chapter II, a new method has been developed using the sol-gel process with polymer additives for dense ceria microsphere fabrication. In addition, the fundamental understanding of sol-gel products has been investigated. In chapter III, we present the fabrication of uranium-based dense microspheres by the same method mentioned in the last chapter. The carbothermal reduction and nitride formation have been studied to prepare the phase pure uranium carbide and nitride microspheres. In chapter IV and chapter V, we describe a novel approach for fabricating porous pure ceria and Zr-doped ceria microspheres. The detailed product generation and approaches for microstructure control are discussed in detail. Moreover, the thermochemical properties of carbon dioxide splitting are studied and analyzed. Overall, this study work includes the fundamental study, fabrication, characterization, and applications of porous and dense cerium- and uranium- based microspheres.
Ma, Jianxing, "Fabrication of Cerium- and Uranium-Based Ceramic Microspheres Using the Sol-Gel Process with Polymer Additives" (2021). All Dissertations. 2847.