Sandwich structured SiC_f/Si₃N₄ composite with discontinuous absorption attenuating layer for temperature-insensitive and broadband microwave absorption

Achieving temperature-insensitive microwave absorption (MA) over a wide temperature range is an immensely challenging task due to the inherent variations in electromagnetic response and energy conversion characteristics. Herein, we present a novel silicon carbide fiber-reinforced ceramic matrix composite (CMC) with a structural-functional-integrated design based on the absorption attenuation layer concept. Through a comprehensive exploration utilizing complementary experimental and computational techniques, we systematically analyze the relationship between key structural parameters of the absorption attenuation layer and microwave absorption characteristics. The results demonstrate that the sandwich-structured SiC_f/Si₃N₄ exhibits exceptional broadband radar wave absorbing properties. Notably, the incorporation of a discontinuous periodic structure within the absorption attenuation layer markedly improves its absorbing capabilities. The experimental findings demonstrate that the discontinuous sandwich-structured SiC_f/Si₃N₄ achieves an effective absorption bandwidth (EAB) of 11.4 GHz (6.6–18 GHz) at a thickness of 3.9 mm, corresponding to a reflection loss of ≤ -10 dB. Furthermore, due to the unique scattering and interference cancellation effects of the metastructure, DSS-SiC_f/Si₃N₄ exhibits temperature-insensitive electromagnetic performance under elevated temperatures. Importantly, the EAB and average reflection loss of the composite remain essentially unchanged even when the temperature is elevated to 600 °C. This work provides a significant advancement in the design of “thinner, wider, stronger, and temperature-insensitive” microwave absorption components with practical applications.