Flame spray pyrolysis of precursors as a route to nano-mullite powder: Powder characterization and sintering behavior

The flame spray pyrolysis of alcohol-soluble precursors allows the synthesis of mullite-composition nanopowders (average size of (similar to 60-100 nm) that, when annealed carefully, provide processable nano mullite powders. The powders have been characterized using several spectroscopic and microscopy methods, including thermal gravimetric analysis, differential thermal analysis, diffuse reflectance infrared Fourier transform spectroscopy, and transmission electron microscopy, Preliminary studies on the pressureless-sintering behavior of these powders are presented. Without additives or any efforts to optimize the process, powder compacts could be sintered to relative densities of > 90%, with grain sizes of < 500 nm at 1600 degreesC.