Nanoparticles‐doped polymer‐derived SiCN ceramic with enhanced mechanical properties and electromagnetic wave absorption.

Polymer‐derived ceramics (PDCs) have become promising candidates for electromagnetic wave (EMW) absorption due to their high thermal stability, design flexibility, and versatile functionality. However, the inevitable porous structure formed during pyrolysis greatly limits its mechanical performance. In this work, Ni–Fe–C/HfO2/SiCN ceramic was prepared by simultaneously doping nickel and iron‐containing metal‐organic framework (Ni–Fe–MOF) nanoparticles and hafnium dioxide (HfO2) nanoparticles into the ceramic precursor, thereby improving its intrinsic brittle structure while granting it extraordinary EMW absorption performance. The flexural strength, flexural modulus, and Vickers hardness of Ni–Fe–C/HfO2/SiCN ceramic were 101.06 MPa, 40.19 GPa, and 13.31 GPa, respectively. These values were 1 132%, 749%, and 191% higher than those of the initial SiCN ceramics. In addition, by optimizing the content of Ni–Fe–MOF, the Ni–Fe–C/HfO2/SiCN ceramic demonstrated satisfying EMW absorption performance from 25°C to 500°C. At 25°C, the minimum reflection loss (RLmin) and effective absorption bandwidth (EAB) were −54.07 dB and 3.95 GHz, covering 94% of the X‐band at a thickness of 2.27 mm. At 500°C, the RLmin and EAB were −33.72 dB and 1.82 GHz, still covering 43% of the X‐band at a thickness of only 1.65 mm. This work provides valuable insight into the integration of mechanical and EMW absorbing functions of PDC materials. [ABSTRACT FROM AUTHOR]