Fabrication of SiC by carbothermal-reduction reactions of diatomaceous earth

In this paper the possibility of using diatomaceous earth as Si precursor for low temperature synthesis of silicon carbide (SiC) by carbothermal-reduction reactions was studied. A diatomaceous earth of Serbian origin and carbon black as reducing agent were used. The green bodies with constant C/SiO₂ ratio (C/Si = 4) were heated at temperatures between 1,250 °C and 1,550 °C with controlled Ar flow atmosphere. Phase evolution was followed as a function of annealing time and sintering temperature. It was found that reaction proceeded via many intermediate phases. The comparatively low reaction temperature is attributed to the nano-porous nature of the raw material. By means of XRD and SEM investigations powders have been characterized. The results show that diatomaceous earth can be very effective source for obtaining of silicon carbide powders.