Preparation and mechanical properties of SiO 2f /BN composites with quasi-sandwich structure for wave transparency

Abstract

Silica fibers reinforced boron nitride composites with a quasi-sandwich structure for high-temperature wave transparency were fabricated by precursor infiltration pyrolysis technology. The loading capacity of the quasi-sandwich structure is close to that of the solid samples as theoretically calculated, in addition to showing enhanced electrical properties and lower density. The test results for the mechanical properties are basically consistent with the theoretical values. The bending strength of the longitudinal and latitudinal I-shaped samples was 74% and 69% that of the solid sample. The fracture behavior of longitudinal and latitudinal I-shaped samples was also investigated by using compression testing. There are two types of fracture behaviors, which vary with the weaving direction. In the case of longitudinal samples, solid and I-shaped samples share a similar fracture appearance, while the latitudinal ones show crack expansion in the opposite direction between the solid and I-shaped samples. The dielectric constant of the quasi-sandwich is much lower than that in the solid samples, which is very beneficial in terms of the wave-transparent properties of structures such as radomes.

Keywords

Wave transparency quasi-sandwich silica fibers reinforced boron nitride composites mechanical properties

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