STRUCTURE OF CARBON PRODUCED BY HYDROTHERMAL TREATMENT OF BETA-SIC POWDER

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