Significantly toughened SiC foams with enhanced microwave absorption via in situ growth of Si3N4 nanowires

Abstract Porous ceramic materials with high electromagnetic absorption capacity, low density, high thermal resistance and excellent mechanical properties are highly desirable in aerospace applications. Here, we synthesized one type of hierarchical SiC composite foams with in situ grown Si3N4 nanowires via a pyrolysis process. The existence and structure of Si3N4 nanowires were characterized by multiple techniques and analysis revealed that the growth of nanowires was based on a typical vapor-solid mechanism. Owing to the presence of a large amount of Si3N4 nanowires, both the mechanical performance and electromagnetic absorption were significantly enhanced. The minimum Reflection loss (RL) of 1.25 mm SiC composite foam reaches −50.3 dB at 16.48 GHz with an effective bandwidth (RL