Transient Pyrolysis of PSZ Precursors to Prepare SiCN with Effective Microwave Absorption Properties in High Temperatures Using RF Thermal Plasma

SiCN materials offer exceptional tunable dielectric properties, which hold significant promise for the customization of electromagnetic wave absorption. In this study, powdery SiCN materials with a relatively large specific surface area and enhanced EMW absorption properties were synthesized, achieved through sustainable and continuous production via RF thermal plasma transient pyrolysis of polysilazane (PSZ) in a controlled N2/Ar atmosphere. Our results show that the SiCN pyrolyzed under N2 and Ar atmospheres achieve excellent effective absorption bandwidths at ultrathin thicknesses of 1.48 and 1.08 mm, respectively, covering 4.845 GHz (13.155–18 GHz) and 2.55 GHz (15.45–18 GHz). Furthermore, after oxidation at 500 °C for 1 h, the SiCN materials exhibit bandwidths of 4.675 GHz (13.325–18 GHz) and 5.525 GHz (12.475–18 GHz) at thicknesses of 1.57 and 1.62 mm, respectively. Radar cross-section simulation proves that it has an excellent absorbing performance, and PSZ-N2 has a better stealth effect. This work provides a pathway for the development of SiCN-based absorbers with broadband EMW absorption capabilities.