Microwave Absorption of SiC/HfC x N 1− x /C Ceramic Nanocomposites with HfC x N 1− x ‐Carbon Core–Shell Particles

The dielectric properties of high‐temperature stable single‐source precursor‐derived SiC/HfC x N 1− x /C ceramic nanocomposites are determined by microwave absorption in the X‐band (8.2–12.4 GHz) at room temperature. The samples synthesized at 1700°C, denoted as SiC/5HfC x N 1− x /C‐1700°C and SiC/15HfC x N 1− x /C‐1700°C ceramics, comprising ≈ 1.3 and ≈ 4.2 vol% HfC x N 1− x , respectively, show enhanced microwave absorption capability superior to hafnium‐free SiC/C‐1700°C. The minimum reflection loss of SiC/5HfC x N 1− x /C‐1700°C and SiC/15HfC x N 1− x /C‐1700°C are −47 and −32 dB, and the effective absorption bandwidth amount to 3.1 and 3.6 GHz, respectively. Segregated carbon, including graphitic carbon homogeneously dispersed in the SiC matrix and less ordered carbon deposited as a thin film on HfC x N 1− x nanoparticles, accounts for the unique dielectric behavior of the SiC/HfC x N 1− x /C ceramics. Due to their large reflection loss and their high chemical and temperature stability, SiC/5HfC x N 1− x /C‐1700°C and SiC/15HfC x N 1− x /C‐1700°C ceramics are promising candidate materials for electromagnetic interference applications in harsh environment.