| Abstract Scope |
Liquid feed-flame spray pyrolysis (LF-FSP) provides ultrafine and nanosized metal-oxide powders by combustion of metallo-organic precursors dissolved in alcohol. In some cases, LF-FSP provides access to metastable phases. For example in MO-Al<sub>2</sub>O<sub>3</sub> systems, 1MO:3Al<sub>2</sub>O<sub>3</sub> [M = Mg, Co, Ni] mole ratio nanopowders are phase-pure spinel nanopowders. Compacts of these materials phase segregate on heating forming the thermodynamically-stable α-alumina/spinel composites. Our objective is to synthesize fine-grained Al<sub>2</sub>O<sub>3</sub>-MgAl<sub>2</sub>O<sub>4</sub>, Al<sub>2</sub>O<sub>3</sub>-CoAl<sub>2</sub>O<sub>4</sub>, and Al<sub>2</sub>O<sub>3</sub>-NiAl<sub>2</sub>O<sub>4</sub> composites with high fracture toughness. Current efforts have led to dense (≥ 95% of theoretical density) ceramic composites with grain sizes of a few microns. By increasing green densities and limiting grain growth during sintering, we hope to develop routes to transparent, polycrystalline nanocomposites for structural applications (e.g. Al<sub>2</sub>O<sub>3</sub>-MgAl<sub>2</sub>O<sub>4</sub>) as well as self-supported catalyst materials (e.g. Al<sub>2</sub>O<sub>3</sub>-CoAl<sub>2</sub>O<sub>4</sub>, and Al<sub>2</sub>O<sub>3</sub>-NiAl<sub>2</sub>O<sub>4</sub>) for use in wide variety of commercial applications such as steam reforming, hydrocarbon cracking, and dehydrogenization. |