Nanofiber-based ceramics are part of a rapidly growing class of engineered advanced ceramics whose market is projected to reach $134 billion worldwide by the year 2024. Ceramic nanofibers have diameters from one to four orders of magnitude smaller than conventional microfibers produced by mechanical drawing. These nanofibers can exhibit unique characteristics such as superplasticity, enhanced machinability, and superior strength and/or toughness that make them attractive for applications in next generation ceramic matrix composites, sensors with high sensitivity and selectivity to various deleterious gases and volatile organic compounds, improved catalysts and catalyst supports, more efficient fuel cells and batteries, and stronger dental composites. However, the technology of nanofiber-based ceramics faces significant challenges in obtaining porous or dense ceramic structures at competitive productivity and cost while preserving the desired properties. This project addresses those challenges through establishing the crucial process-structure-property-performance relationships for selected nanofiber-based ceramic structures, and building the realistic models which can be applied to various nanofibrous ceramic systems to explain and predict the material performance and to advance development of sustainable manufacturing technology and commercial products. Students at different levels (university and high-school) are involved in every aspect of this study and are developing hands-on skills needed for highly specialized jobs in expanding advanced ceramics and associated research and manufacturing domains.
TECHNICAL DETAILS: This project investigates the roles of initial porosity, structure and ordering of individual oxide ceramic nanofibers during sintering on the resulting microarchitecture and mechanical properties. The key aspects being addressed include: How the nanofibrous state can be preserved during sintering and lead unique and useful properties not otherwise achievable in traditional materials. How structure, porosity, and interaction of nanofibers affect the properties of a fibrous ceramic assemblies. The maximum density that can be achieved while maintaining the nanofibrous structure. Identification of any sintering phenomena associated exclusively with the nanofiber shape. The research activities are carried out with several representative oxide ceramic nanofibers (alumina, silica, zirconia, Mg-Al spinel, and combinations thereof) arranged into 2-D and 3-D nanofibrous constructs. The research is centered on the investigation of (i) effects of the individual fiber behavior and fiber-fiber interaction in the nanofibrous assembly during calcination/sintering; (ii) relationships between the ceramic nanofiber packing, sintering behavior and final structure of nanofiber-based ceramics; (iii) structure /mechanical property relationships in fabricated nanofiber-based constructs, and (iv) building models that are applicable to various nanofibrous ceramic systems to explain and predict material behavior. An advanced high-yield free-surface electrospinning method is employed in this study to produce the ceramic precursor fibers and fibrous assemblies in sizeable quantities with characteristics not achievable by other methods. The project involves two graduate students on the Ph.D. track and provides the research opportunities on a yearly basis to at least three undergraduate students and three local high-school students interested in science.
