Single source precursor derived SiBCNHf ceramic with enhanced high‐temperature microwave absorption and antioxidation

Electromagnetic (EM) wave-absorbing materials with high-temperature-resistance are urgently desirable to eliminate EM interference in extreme conditions. Precursor derived ceramics (PDC) route is being evolved as an effective strategy to solve the puzzle. Herein, a single source hyperbranched polyborosilazane precursor containing hafnium (hb-PBSZ-Hf) is introduced and the SiBCNHf ceramic is obtained by further pyrolysis. The micro-sized tissues including HfC, SiC, HfB₂ nanocrystals and segregated carbons are in situ generated during annealing which not only increase EM wave absorption ability (minimum reflection coefficient (RC_min) is -56.71 dB with a thickness of 2.5 mm, effective absorption bandwidth (EAB) is 3.4 GHz), but also improve antioxidation property (less than 2 wt.% mass fluctuation at 1400 °C in air). Theoretical simulation of complex permittivity suggests that SiBCNHf ceramic has an RC_min of less than -5 dB for the whole X-band even at 1100 °C. Such SiBCNHf ceramic with superior high-temperature-resistance and antioxidation performance derived from single source precursors possesses great potential for EM wave absorbing coatings in high-temperature and harsh environments.