In the synthesis of silicon nitride (Si3N4) based powders by carbothermal reduction-nitridation of diatomaceous earth, the effects of addition of silicon nitride powder on the phase composition, particle size and shape were investigated in this paper. Activated carbon was used as carbon sources. In order to obtain better quality Si3N4 powder in a faster and more efficient way, α-Si3N4 powder was introduced into starting mixtures as seeds. The starting mixtures of diatomaceous earth, carbon source and commercial α-Si3N4 powder (5,10,15 and 20 wt.%) were thermally treated at 1350 °C and 1450. X-ray diffraction (XRD), infrared spectroscopy with Fourier transform (FTIR) and scanning electron microscopy (SEM) were employed to characterize the phases, functional groups, microstructure of the obtained powders. The major reduction of diatomaceous earth took place at 1450 °C. At 1350 °C particles retained the morphological characteristics of the starting diatomaceous earth. At 1450 °C, observed particles possess a polygonal habitus, which is characteristic for silicon nitride crystals.X Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 26-27, 2022; Belgrad
