SiC/Co composite fibers with enhanced conductivity and magnetic coupling developed for reinforcing and high-efficiency electromagnetic absorbing (EMA) materials

Abstract

For the design requirements for structural/functional integrated components, it is urgent to find EMA materials combining high-efficient EMA performances and load bearing capacity. Herein, high-strength SiC fibers are modified by Co nanoparticles to construct SiC/Co composite fibers by the liquid-phase method and subsequent hydrogen-thermal annealing. The conductivity of single SiC/Co fiber can be improved by increasing the diameter and content of Co nanoparticles, which leads to enhanced conduction loss and then dominates the dielectric loss. The cross-linked SiC/Co fibers with high conductivity also contribute to significant eddy current loss. Micromagnetic simulation based on Landau-Lifshitz-Gilbert equation (LLG) quantificationally reveals that reducing Co diameter from 140 nm to 30 nm can enhance the ferromagnetic loss by 17.19 times, and this law also can be confirmed by the effect medium theory. Maximum reflection loss (RLmax) can reach −78.0 dB at 11.8 GHz and effective absorbing bandwidth with RL < −10 dB (ERL10) of 6.6 GHz can be observed in these SiC/Co-400 filled specimens with the thickness of only 2.7 mm. These SiC/Co fibers present excellent absorbing performances and display the potential for developing into load-bearing and high-efficiency EMA materials.