High-purity Si3N4 powder with no free Si was prepared at a low N-2 pressure of 140-200 kPa by preheating-assisted combustion synthesis with a heating temperature of 500-750 degrees C. The effects of diluent proportion, preheating temperature, and N-2 pressure on the combustion parameters were investigated. By increasing the N-2 pressure, both the combustion temperature and propagation velocity of combustion wave were enhanced, and the lower limit of preheating temperature for successful combustion synthesis was decreased. As a compromise between direct nitridation and conventional combustion synthesis, preheating-assisted combustion synthesis provides an efficient and practical method for industrial production of Si3N4 powders under a moderate condition and on a large scale. (c) 2012 Elsevier Ltd. All rights reserved.