  This work presents the synthesis of SiC nanowires floating in a gas stream
through the vapour-liquid-solid (VLS) mechanism using an aerosol of catalyst
nanoparticles. These conditions lead to ultrafast growth at 8.5 {\mu}m/s
(maximum of 50 {\mu}m/s), which is up to 3 orders of magnitude above
conventional substrate-based chemical vapour deposition. The high aspect ratio
of the nanowires (up to 2200) favours their entanglement and the formation of
freestanding network materials consisting entirely of SiCNWs. The floating
catalyst chemical vapour deposition growth process is rationalised through
in-situ sampling of reaction products and catalyst aerosol from the gas phase,
and thermodynamic calculations of the bulk ternary Si-C-Fe phase diagram. The
phase diagram suggests a description of the mechanistic path for the selective
growth of SiCNWs, consistent with the observation that no other types of
nanowires (Si or C) are grown by the catalyst. SiCNW growth occurs at 1130
{\deg}C, close to the calculated eutectic. According to the calculated phase
diagram, upon addition of Si and C, the Fe-rich liquid segregates a carbon
shell, and later enrichment of the liquid in Si leads to the formation of SiC.
The exceptionally fast growth rate relative to substrate-based processes is
attributed to the increased availability of precursors for incorporation into
the catalyst due to the high collision rate inherent to this new synthesis
mode.
