Increased microwave absorption property of porous Si3N4 ceramics by loading polymer-derived SiCN for a multifunctional design

Abstract

Ceramic materials with wave-transparent in-band and stealth out-off-band characteristics are rather urgent in the aerospace field. Porous Si₃N₄ ceramic, a wave-transparent material used to produce radomes and antenna windows, is considered to be one of the most promising ceramics for developing stealth-transmission-structure-integrated materials. If a functional phase with microwave absorption ability is loaded into porous Si₃N₄ ceramic, the resultant composite not only retains the mechanical strength of the Si₃N₄ ceramic, but also adds microwave absorption capability, laying the groundwork for the development of stealth-transmission-structure-integrated composite materials used in the radome field. Polymer-derived SiCN ceramics possess excellent composition designability and electromagnetic performance, along with low density and high-temperature resistance, which make it an ideal microwave-absorption phase in Si₃N₄ ceramic. This study employed porous Si₃N₄ ceramic as a support framework, which was loaded with SiCN to prepare a SiCN/Si₃N₄ multiphase ceramic, and the influence of the pyrolysis temperature on the microstructure and microwave absorption properties of as-fabricated SiCN/Si₃N₄ were investigated.