Regulatory mechanism of chemical vapor deposited BN interface on electromagnetic wave absorption properties of SiC fibers

The chemical vapor deposition (CVD) of BN interface layers on SiC fiber-reinforced ceramic matrix composites shows considerable promise for applications in electromagnetic wave absorption. This study systematically examines the influence of the BN interfacial layer on the microstructure and electromagnetic wave absorption performance of SiC fibers. Utilizing various characterization techniques, including SEM-EDS, XRD, XPS, Raman spectroscopy, and dielectric parameter measurements, the study reveals the regulation mechanisms of material microstructure, chemical composition, and electromagnetic properties with respect to BN deposition time (ranging from 0 to 20 h). The results demonstrate that the incorporation of the BN interfacial layer significantly enhances the surface characteristics and dielectric properties of the SiC fibers. As the deposition time increases, the fiber surface becomes progressively covered by a uniform and dense BN layer, and a stable structure based on B-N bonds is formed. The sample with a 15-hour deposition time exhibited optimal impedance matching and the best wave absorption performance, achieving excellent reflection loss within the 2–5 mm thickness range in the X-band (8.2–12.4 GHz). Cole-Cole plot analysis further indicated that the BN interfacial layer substantially improved the dielectric loss capability of the material by enhancing the polarization relaxation mechanism. Additional investigations revealed that the BN interfacial layer enhances the wave absorption performance of SiC fibers through a combination of mechanisms, including modifications to conductive loss, interface polarization, and defect polarization. These findings provide new insights and an experimental foundation for the design and optimization of high-performance, wide-band electromagnetic wave absorbing composites.