Energy-Related Ceramics and Composites
Capturing particulates from diesel engine exhausts, providing channels for gaseous transport in fuel cells, and insulating sensitive components from temperature extremes all rely on porous materials. Each of these applications requires porous networks with distinctive size, shape, roughness, and connectivity to control their flow, filtering, or insulating capabilities. Many energy-related applications also require materials (ceramics) that maintain strength and robustness to temperatures in excess of 1500°C. Advanced ceramics surpass conventional materials for high-temperature applications. Our work focuses on the use of ceramic slurries and preceramic polymers to create high-temperature porous ceramics by freeze casting. By developing an understanding of the solidification and, in the case of preceramic polymers, the chemistry of these freeze-casting systems, creating versatile pore architectures is possible, thereby expanding the use of porous ceramics for environmental and energy needs.
A key aspect of a porous solid is the quantification of its pore network as characterized by pore size, morphology, tortuosity and connectivity. We aim to gain an understanding of the network as well as how pores are formed, stabilized or eliminated during processing and in use by coupling synchrotron-based characterization methods, specifically X-ray computed tomography, with small-angle X-ray scattering and various microscopies. Both 2D and 3D visualization techniques aid in interpretation. These same techniques also allow characterization of the analogous 3D-interconnected electrolyte network in Li-ion batteries in order to visualize and quantify degradation mechanisms.
Thermal and environmental barrier coatings for power generation components are needed for enhanced efficiency in the next generation of engines such as industrial gas turbines. Ceramic coatings allow reduced cooling or increased combustion temperatures. Likewise, they serve as environmental barriers to keep corrosive species from the underlying component. Our work focuses on the characterization of plasma-sprayed coatings using the Advanced Photon Source at Argonne National Laboratory to understand residual stresses and phase evolution during thermal cycling. Both stress and chemistry can have important influences on coating stability, and hence, component lifetime.
Scientific research on the visual arts in the US is typically conducted in a few dozen museums or cultural institutions with the appropriate facilities and expertise. However, given the nature of problems associated with the study and preservation of cultural heritage objects, these are opportunities that naturally inspire scientists and engineers beyond the museum. For example, polymer scientists can see the similarities in the curing of artists’ paints with technological coatings. Chemists can bring new analytical techniques to the identification of pigments especially difficult to discern. Electrical engineers with expertise in digital imaging can reveal pentimenti in works of art. Materials scientists can unearth the sources of color in carved minerals. Our involvement with the Northwestern University/Art Institute of Chicago Center for Scientific Studies in the Arts (NU-ACCESS) provides opportunities to pursue such research.