Fabrication and properties of SiNO continuous fiber reinforced BN wave-transparent composites

SiNO continuous fiber reinforced boron nitride (BN) wave-transparent composites (SiNOf/BN) have been fabricated by a precursor infiltration pyrolysis (PIP) method using borazine as the precursor. The densification behavior, microstructures, mechanical properties, and dielectric properties of the composites have been investigated. After four PIP cycles, the density of the composites had increased from 1.1 g·cm−3 to 1.81 g·cm−3. A flexural strength of 128.9 MPa and an elastic modulus of 23.5 GPa were achieved. The obtained composites have relatively high density and the fracture faces show distinct fiber pull-out and interface de-bonding features. The dielectric properties of the SiNOf/BN composites, including the dielectric constant of 3.61 and the dielectric loss angle tangent of 5.7×10−3, are excellent for application as wave-transparent materials.