Structure of carbon produced by hydrothermal treatment of beta-SiC powder

Interaction of a beta-SiC powder with supercritical water has been studied in the temperature range 600-800 degrees C under 100 500 MPa pressure. Examination of the composition of corrosion products by Raman and IR spectroscopy, XRD, SEM and TEM demonstrated that carbon and silica are formed after the hydrothermal treatment of SiC. Their structure varies depending on the experimental conditions. Amorphous and crystalline SiO2 (alpha-quartz, alpha-cristobalite and traces of tridymite) were found. Along with graphite and amorphous sp(2) carbon, disordered or poorly crystallised sp(3) carbon (diamond) was present in the reaction products. The formation of sp(2) vs. sp(3) carbon is discussed.