Combustion synthesis of B ₄ C@TiB ₂ ‐TiC composite powders and their electromagnetic wave–absorbing properties

Abstract Using B 4 C and Ti as raw materials, B 4 C@TiB 2 ‐TiC composite powders with different B 4 C excess coefficients were synthesized via combustion synthesis. The phase composition and microstructure of B 4 C@TiB 2 ‐TiC composite powders were characterized by x‐ray diffractometry, Raman spectra, scanning electron microscopy, and transmission electron microscopy. The results show that the major phases are B 4 C and TiB 2 when the B 4 C excess coefficients are from 4 to 8, whereas the major phases are B 4 C, TiB 2 , and TiC when the B 4 C excess coefficients are from 8 to 11, and the microstructure of the B 4 C@TiB 2 ‐TiC composite powders is TiB 2 sheets and TiC particles wrapped with plate‐shaped B 4 C particles. TiB 2 and C were obtained by a reaction between molten Ti and solid‐phase B 4 C, whereas TiC was obtained by a reaction between molten Ti and diffused C, forming the core–shell structure. Electromagnetic wave (EMW)‐absorbing properties of the B 4 C@TiB 2 ‐TiC EMW‐absorbing materials were investigated in the X‐band. The effective absorption bandwidth (EAB) and the minimum reflection loss (RL min ) reach, respectively, 2.14 GHz and −42.35 dB when the B 4 C excess coefficient is 6, and the excellent EMW‐absorbing properties are mainly attributed to multiple heterogeneous interfacial polarization losses. Overall, B 4 C@TiB 2 ‐TiC composite powders with core–shell structure and excellent EMW‐absorbing properties can be conveniently synthesized.