Paul Fuierer, PhD Research

Aerosol Deposition (AD) is a new method to produce ceramic films. Similar to cold spray of metals, dry ceramic particles are accelerated to near sonic velocities, and their high kinetic energy is transferred to fracture and bonding energy upon impact with the substrate, resulting in dense, nano-poly-crystalline films. The process takes place at room temperature, and can be done using any substrate material, ceramic, metallic, or plastic.

This is a new and exciting capability in our laboratory. We benefit by working in partnership with the University of Bayreuth, Germany.

Research is underway to investigate alternative oxygen ion conducting ceramics for medium temperature solid oxide fuel cells (SOFCs). The bidimensional conductivity in some of these compounds requires novel ceramic processing techniques to achieve the necessary texture in planar thick films.

Work on this Project is currently being sponsored by Materials World Network, under the National Science Foundation.

My group has developed novel hierarchical TiO2 thick film microstructures, including sol-gel nano-crystalline anatase and micro-scale rutile particles, with potential for increasing solar cell efficiencies and economizing processing. New approaches are being explored.

We have a unique expertise in fabricating certain polycrystalline ceramics with very high crystallographic orientation (texture). Techniques involve hot-forging and superplastic deformation (bulk), tape-casting (thick film) and novel sol-gel (thin film). Crystallographically oriented films of low symmetry materials often display superior electronic, optical, magnetic and even mechanical properties. Bismuth titanate, Bi4Ti3O12, has been used as a model ceramic material due to its intrinsic structural anisotropy and its useful ferroelectric and piezoelectric properties, but we have fabricated many others as well (particularly ceramics with a layered perovskite type structure). Several of these dense and highly textured materials have recently displayed some of the very lowest thermal conductivity values of any known ceramic.

The use of a functional interface to weaken the fiber-matrix bond in oxide/oxide composites may enhance fiber-pullout and therefore toughness. This approach may lead to new composite materials with improved high temperature toughness and stability for aerospace and other demanding applications. Layered perovskite compounds offer interesting characteristics for this application including easy cleavage planes, and resistance to high temperature and oxidizing environments. Research has been done to identify the most useful perovskite layer oxides compounds, produce multi-layered ceramic composites, and study crack-propagation paths near the interfaces.