  Theoretical models predict the condensation of silicon carbide around host
stars with C/O ratios higher than 0.65 (cf. C/O$_{\mathrm{Sun}}$ = 0.54), in
addition to its observations in meteorites, interstellar medium and
protoplanetary disks. Consequently, the interiors of rocky exoplanets born from
carbon-enriched refractory material are often assumed to contain large amounts
of silicon carbide. Here we aim to investigate the stability of silicon carbide
in the interior of carbon-enriched rocky exoplanets and to derive the reaction
leading to its transformation. We performed a high-pressure high-temperature
experiment to investigate the reaction between a silicon carbide layer and a
layer representative of the bulk composition of a carbon-enriched rocky
exoplanet. We report the reaction leading to oxidation of silicon carbide
producing quartz, graphite, and molten iron silicide. Combined with previous
studies, we show that in order to stabilize silicon carbide, carbon saturation
is not sufficient, and a complete reduction of Fe$^{2+}$ to Fe$^{0}$ in a
planetary mantle is required, suggesting that future spectroscopic detection of
Fe$^{2+}$ or Fe$^{3+}$ on the surface of rocky exoplanets would imply the
absence of silicon carbide in their interiors.
