High-temperature-stable CNT/SiC ultrafine fibers with superior electromagnetic-wave-absorbing performance via CNT-driven multiple lossy phase modulation

CNT/SiC UFs with uniformly dispersed CNTs and tunable multiple lossy phases were successfully prepared. • CNT/SiC UFs exhibit excellent high-temperature stability (1500 °C) and low thermal conductivity (∼197 mW m -1 K -1 at 1500 °C). • CNT/SiC UFs demonstrate outstanding EMW absorption performance ( RL min of -45.52 dB and EAB of 6.44 GHz at 2.7 mm thickness). Silicon carbide (SiC) fibers are promising lightweight and high-temperature-stable electromagnetic wave (EMW)-absorbing materials for aerospace applications. However, their EMW absorption performance severely degrades at high-temperature. Recently, incorporating carbon nanotubes (CNTs), which exhibit excellent high-temperature stability, large specific surface area, and electrical conductivity, into SiC fibers has been proved to be effective in optimizing the high-temperature stability and EMW absorption performance of SiC fibers. However, the non-uniform dispersion of CNTs and the instability of the impedance-matching phase (SiC x O y ) at high-temperature often result in the degradation of mechanical properties and EMW absorption performance. Here, these obstacles are overcome by preparing CNT/SiC ultrafine fibers (UFs) with uniformly distributed CNTs and multiple thermally stable phases (CNTs, SiC, and free carbon). The CNT/SiC UFs exhibit an effective absorption bandwidth (EAB) of 6.44 GHz (2.7 mm thickness) and a minimum reflection loss of −45.52 dB. Even after thermal treatment at 1500 °C, the fibers exhibit excellent EMW-absorbing performance, with an EAB of 4.43 GHz at a 2.7 mm thickness, significantly surpassing the performance of SiC UFs (2.47 GHz). The prepared CNT/SiC UFs also display excellent flexibility, high-temperature stability, and ultra-low thermal conductivity (∼28 mW·m −1 ·K −1 and 197 mW·m −1 ·K −1 at ambient temperature and 1500 °C, respectively). The outstanding integrated properties of CNT/SiC UFs make them ideal EMW-absorbing materials for aerospace applications under extreme conditions. Download: Download high-res image (231KB) Download: Download full-size image