Effects of Precursor Infiltration and Pyrolysis Cycles on Properties of Hollow Silica Fiber Reinforced Nitride Composites

Abstract

2.5-Dimension hollow silica fiber reinforced nitride (2.5D HSFRN) composites were fabricated by repeated infiltration and pyrolysis from hybrid polyborosilazane precursor. The effects of precursor infiltration and pyrolysis (PIP) cycles on densification behavior, mechanical properties, dielectric properties, and microstructures of the composites were investigated. With increasing PIP cycles, the density of 2.5D HSFRN composites increases, the mechanical properties increase accordingly, however, the dielectric properties decrease. The composites prepared after three PIP cycles, which have moderate flexural strength of 77.4MPa and elastic modulus of 20.7GPa, low dielectric constant of 2.98 and loss angle tangent of 3.9×10-3, exhibit suitable mechanical and dielectric properties. The calculation results of dielectric performance show that 2.5D HSFRN composites have good broadband wave-transparent properties, which result from high purity hollow silica fibers with excellent dielectric properties and low density nitride matrix.