Formation of carbon-based microfibers during sintering of bentonite

We report the formation of carbon-based fibers inside a bentonitic matrix during sintering of a ceramic body. Since this peculiar bentonite contained organic matter and iron, the formation of these fibers may be analogous to the synthesis of carbon nanotubes by chemical vapor deposition or spray pyrolysis. In these processes iron acts as catalyst to favor graphitization of the carbon source. During sintering and melting of the bentonite, the thermal treatment restricted diffusion of air into the interior of the clay. This created bubbles containing a reducing atmosphere as well as the elements needed to synthesize carbon-based fibers.