Engineering Commons^™

Optimizing Electrospun Ceramic Nanofiber Strength Through Two-Step Sintering, Michael Ross

Materials Engineering

Two-step sintering (TSS) consists of a high-temperature step and immediate cooling to a sintering temperature for an extended sintering time, where grain growth is suppressed by severe densification during the high-temperature step. TSS is adopted to enhance mechanical properties of electrospun ceramic nanofibers (CNFs), a class of porous ceramics used for environmental remediation, optoelectronics, and filtration. PVP and Ga(NO₃)₃ nanofiber mesh, provided by Lawrence Livermore National Laboratory, was shaped, oxidized, and two-step sintered to form a nanocrystalline β-Ga₂O₃ CNF tube using a high-temperature step of 1,000^oC. Sintering temperatures and times varied from …

Synthesis And Applications Of Ceramic (Silicon Carbide And Silicon Nitride), Metallic (Cobalt(0)) And Polymeric (Polyurethane) Aerogels, Parwani M. Rewatkar

Doctoral Dissertations

"A new method has been demonstrated for the synthesis of monolithic ceramic and purely metallic aerogels from xerogel powder compacts, and the use of polyurethane aerogels based on cyclodextrins as efficient desiccants.

I. Highly porous ( > 80%) monolithic SiC and Si₃N₄, aerogels were prepared from compressed compacts of polyurea-crosslinked silica xerogel powders. The process is time efficient as solvent-exchange through powders is fast, and energy efficient as it bypasses drying with supercritical fluids. The final ceramic objects were chemically pure, sturdy, with compressive moduli at 37 ±7 MPa and 59 ± 7 MPa, and thermal conductivities …