Salt-assisted combustion synthesis of β-SiAlON fine powders

A novel method of producing submicron-size β-SiAlON powders by combustion synthesis using NaCl as a diluent was proposed. The combustion synthesis was carried out with the raw materials Si, SiO2, and Al powders, and varying amounts of NaCl under a nitrogen pressure of 1 MPa. Phase compositions and particle morphologies of the synthesized powders were analyzed. The results revealed that as the z-values increased, the amount of NaCl needed to complete the reaction increased, which in turn decreased the particle size of the product. With small z-values, single-phase products were obtained; however, with large z-values, NaCl and unreacted Si remained in the products due to the large amount of liquid phase. NaCl acted not only as a diluent by absorbing the heat generated by the reaction but also as a diffusion barrier between β-SiAlON particles, which greatly limited the growth of β-SiAlON crystals.