Growth of One-Dimensional Nanostructures in Porous Polymer-Derived Ceramics by Catalyst-Assisted Pyrolysis. Part II: Cobalt Catalyst

Via catalyst-assisted pyrolysis, Si3N4 and SiC nanowires were produced on the cell walls of polymer-derived ceramic foams. The pyrolysis atmosphere and temperature were the main parameters affecting their development: silicon nitride singlecrystal nanowires formed under nitrogen, while silicon carbide ones were produced under argon, and their amount increased with the increasing pyrolysis temperature. Brunauer–Emmett– Teller analysis showed that the presence of the nanowires afforded high specific surface area (SSA) values to the macroporous ceramic foams, ranging from 10 to 110 m2/g. Co-containing samples developed higher SSA values, especially after pyrolysis at 14001C in N2, than samples containing Fe as a catalyst. The differences were explained in terms of morphology (diameter and assemblage), which depended on the processing conditions and the catalyst type (Co or Fe).