Silicon Nitride is considered as an important material for use in structural applications. Its performance is severely influenced by modern synthesis processes. In the present work, silicon nitride powder synthesis was performed using liquid silicon tetrachloride and gaseous ammonia, at low temperature and inert atmosphere. Diimide pyrolisis was made on temperature between 1300 and 1500 0C. A Taguchi design of experiments methodology was applied, aiming to obtain powders with appropriated characteristics for structural applications. On pyrolisis, the use of alumina based substrates resulted on SIALON phase formation, probably originated from oxygen reaction, provided from alumina. Silicon carbide substrates and alumina recovered with silicon nitride enhance synthesis of pure silicon nitride powder.