Synthesis of SiC from poly(silyne-co-hydridocarbyne) under CO2 atmosphere

It is well known that advanced ceramics from polymer precursor have been producing upon heating under an ambient and inert atmosphere, like argon or nitrogen gases over 40 years. However, the effect of these gases on the production and on the crystal form of ceramic obtained are not well understood during thermal treatments. Here, we report to demonstrate a novel, simple and a common method for the production of crystalline SiC ceramic species using a polymeric precursor, which is poly(silyne-co-hydridocarbyne) (PSC), upon heating under an ambient and CO2 atmosphere. The Raman and X-ray analysis showed that polycrystalline SiC production was successfully achieved at 1000 and 750 degrees C under CO2 atmosphere. Amorphous ceramic material was obtained at 500 degrees C under CO2 atmosphere. Also, the results showed that SiC powder produced under CO2 has not crucial differences in crystal forms that is produced under argon atmosphere. SiC produced at 1000 degrees C is mostly Moissanite-5H, at which temperature there is also a small amount of Moissanite-8H and Moissanite-84R. SiC produced at 750 degrees C is mostly Moissanite-5H. There is also the trace of Moganite and Coesite, which are crystal forms of SiO2. As a result, the type of produced SiC depends on process temperature and production atmosphere.