Enhanced microwave absorbing properties of Y2O3 modified PDC SiCN ceramics with heterogeneous amorphous interface

Abstract

Polymer derived SiCN ceramics (PDC SiCN) are the key high-temperature matrix materials for structural and stealth integrated ceramic matrix composites (CMC). However, low crystallization degree and homogeneous microstructure of PDC SiCN ceramics results in the lack of effective microwave attenuation mechanism. Hence, a new kind of nonmagnetic metal oxide (Y2O3) was in-situ formed in SiCN ceramics to enhance the conductivity loss as well as the polarization loss. Y2O3 modified PDC SiCN ceramics (SiCN-Y2O3 ceramics) were fabricated by pyrolysis polysilazane with different Y(NO3)3 content at 900 ºC. For the SiCN-Y2O3 ceramic, Y2O3 nanoparticles were dispersed in SiCN ceramic uniformly forming a large number of Y2O3-SiCN heterogeneous amorphous interface, defects and dipole polarization to enhance its microwave absorbing properties. Due to the multiple polarization loss mechanism, SiCN-Y2O3 ceramic with 10 wt% Y(NO3)3 content achieved excellent microwave absorption performance at a wide thickness range with the microwave absorbing efficiency more than 90% in the whole X band, and the RCmin could reach − 50.2 dB at the thickness of 3.5 mm.