Synthesis of Porous Silicon Nitride-Boron Nitride Composites by Gel-Casting and PIP.

The SiN-BN composites were prepared by gel-casting and precursor infiltration and pyrolysis route using borazine as the precursor. The composition, mechanical, microstructural, and dielectric properties of the composites were investigated. The composites are composed of h-BN, α-SiN, and β-SiN. The typical density, porosity, flexural strength, elastic modulus, and fracture toughness of the composites are 2.21 g/cm, 17.8%, 185.59 MPa, 69.13 GPa, and 2.47 MPa m, respectively. The dielectric constant and loss tangent of the composites are 4.507-4.635 and 1.06 × 10-1.97 × 10 at the frequency of 7-18 GHz. Desirable properties of the composites have been achieved. [ABSTRACT FROM AUTHOR]