Phase-Transformation Nanoparticles Synchronously Boosting Mechanical and Electromagnetic Performance of SiBCN Ceramics

Precursor-derived silicoboron carbonitride ceramic (PDC-SiBCN) has attracted significant attention as an advanced electromagnetic (EM) wave-absorbing material. However, the inherent porous and brittle characteristics limit its application as a structural load component in an EM interference environment. In this study, phase-transformation HfO₂ nanoparticles were incorporated into PDC-SiBCN to reduce volume shrinkage, improve bonding interactions, and control structural defects, simultaneously boosting the plastic deformation and EM performance of brittle ceramics. The obtained HfO₂/SiBCN ceramic showed enhanced flexural strength of up to 430.1% compared with that of the pure SiBCN ceramic. Furthermore, the HfO₂/SiBCN ceramic also demonstrated excellent high-temperature EM absorption. The minimum reflection coefficient (RC_min) could reach −45.26 dB, and the effective absorption bandwidth (EAB) covered 2.80 GHz of the X band at 2.28 mm thickness at room temperature. Furthermore, the RC_min can still reach −44.83 dB, and the EAB can cover 2.4 GHz at 1.58 mm even at 1073 K. This work shows that phase-transformation nanoparticles could simultaneously improve the deformation ability and EM wave absorption properties of SiBCN ceramics. The results could guide the design and preparation of PDCs with strong carrying capacity and excellent EM absorption, even in harsh environments.