Ultralong SiC Nanowires for Electromagnetic Wave Absorption

Ultralong cylindrical and chain-beaded SiCnw with strong wave-absorbing capabilities were successfully synthesized by carbothermal reduction, employing coconut active charcoal as a carbon source, silicon powders as a silicon source, and graphite flake as a growth matrix. The sintering temperature and holding duration considerably influenced the composition, microstructure, morphology, dielectric properties, and absorption traits of SiCnw. Elevated sintering temperature facilitated the transformation from cylindrical to chain-beaded SiCnw. Extending the holding duration from 2 h to 6 h promoted SiCnw growth in both longitudinal and transverse directions. At 1200 °C for 2 h, the cylindrical SiCnw exhibited superior absorption properties, featuring an RL of −65.40 dB at 4.5 mm and 5.32 GHz, along with an EAB of 1.66 GHz spanning 4.64–6.30 GHz. When sintered at 1200 °C for 6 h, the cylindrical SiCnw demonstrated an RL of −57.70 dB at 2.00 mm and 14.86 GHz, along with an EAB of 5.50 GHz between 12.50 and 18.00 GHz. At 1400 °C for 6 h, the chain-beaded SiCnw exhibited an RL of −47.00 dB at 3.50 mm and 5.96 GHz and an EAB of 1.56 GHz across 5.30–6.86 GHz. These insights accentuate the considerable possibilities of SiCnw in electromagnetic wave absorption applications.