Mechanical and dielectric properties of porous Si2N2O–Si3N4 in situ composites

Abstract Mechanical and dielectric properties of porous Si 2 N 2 O–Si 3 N 4 in situ composites fabricated for use as radome by gel-casting process were investigated. The flexural strength of the Si 2 N 2 O–Si 3 N 4 ceramics is 230.46 ± 13.24 MPa, the complex permittivity of the composites varies from 4.34 to 4.59 and the dissipation factor varies from 0.00053 to 0.00092 from room temperature to elevated temperature (1150 °C) at the X-band. In the porous regions, some Si 2 N 2 O fibers (50–100 nm in diameter) are observed which may improve the materials properties.