Preparation of SiNO_f/BN High Temperature Wave-Transparent Composites by Precursor Infiltration and Pyrolysis Method

摘要

SiNO fibers reinforced BN wave-transparent composites (SiNO_f/BN) were fabricated through precursor infiltration and pyrolysis (PIP) method using borazine as precursor. The effect of pyrolysis temperature on the densification behavior, microstructures, mechanical properties and dielectric properties of the composites was investigated. The results suggest that with the increase of the pyrolysis temperature from 800 °C to 1000 °C, the density, mechanical properties and dielectric constant of the composites are increased, but the infiltration efficiency varies little. At the pyrolysis temperature of 1000 °C, the density of SiNO_f/BN composites is 1.84 g.cm~(-3) and the flexural strength and elastic modulus are 148.2 MPa and 26.2 GPa respectively. The dielectric properties, including dielectric constant of 3-4 and dielectric loss angle tangent of below 7×10~(-3), obtained at three different temperatures are excellent for the SiNO_f/BN composites applied as wave-transparent materials.