Processing and Characterization of Energy-Related Ceramics and Composites
As ceramics are considered for complex applications, one component may serve many disparate functions, e.g., wear resistance with low weight. Graded or layered microstructures, often including controlled porosity, may meet such demands. Such materials can be processed via gelcasting, where powders are suspended in a polymer that undergoes a liquid-gel transition. The position or orientation of fugitive phases (for pores) and particles of different chemistry can be controlled when the polymer is in the liquid state. Once a rigid gel forms, particles are rendered immobile, the polymer removed and the ceramic is sintered via traditional routes. We are developing these processing methods for multifunctional ceramics including solid oxide fuel cells and thermoelectric devices.

A second interest is in SiC-based cellular ceramics, derived from natural scaffolds. These so-called "biomorphic" silicon carbides are produced by pyrolyzing wood to create the carbon scaffold. The scaffold or template is then used for silicon infiltration and reaction to create versatile SiC-based porous materials. The porous SiC can be further infiltrated or electroplated with aluminum, copper, nickel, etc. to create ceramic-metal composites.  We are interested in both mechanical and thermo-mechanical properties of these materials.

Finally, thermal and environmental barrier coatings for engine components are needed for enhanced efficiency in the next generation of engines such as microturbines and 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 development of plasma-sprayed coatings and their characterization using the Advanced Photon Source at Argonne National Laboratory to understand residual stresses and phase evolution during thermal cycling.

(left-to-right) Sarah Miller, Amanda Childers, Harold Hsiung, Fabian Stolzenburg, Matt Johnson, Katherine Faber, Zhao Liu.

Department of Materials Science and Engineering
Robert R. McCormick School of Engineering and Applied Science
Northwestern University