Self-propagating high-temperature synthesis of Si₂N₂O powder and its performance verification

In this study, Si₂N₂O powder was synthesized via self-propagating high-temperature synthesis (SHS). The effects of raw material ratio, diluent amount, ammonium salt content, and nitrogen pressure on the phase composition of the product were systematically investigated. When the mass ratio of elemental silicon to amorphous silica is 7:8.7, with 2% ammonium salt employed under a nitrogen pressure of 7 MPa, the resulting Si₂N₂O exhibits relatively high purity. To evaluate the performance of the SHS-derived powder, complex-shaped ceramics were fabricated by gas pressure sintering, achieving a density of 2.69 g/cm3, a flexural strength of 176.4 MPa, a dielectric constant of 5.09, and a dielectric loss of 0.008. This work provides a novel processing route and theoretical foundation for the efficient preparation and large-scale application of Si₂N₂O wave-transmitting ceramic materials.