Combustion synthesized boron carbide powders by different organic carbon sources and microwave absorbing properties

Abstract Boron carbide powders were synthesized by combustion synthesis using organics chitosan, dextrin, cellulose, starch, and polyvinyl chloride (PVC) as carbon sources. The microwave absorbing properties of boron carbide powders synthesized by different carbon sources were investigated. The results showed that the powders synthesized using organic compounds containing Cl and N atoms as carbon sources have better absorbing properties. The peak value of reflection loss of boron carbide powder prepared with chitosan as carbon source is −46.41 dB at 2.1 mm thickness, with an effective absorption range of 9.21–12.30 GHz and an effective absorption bandwidth of 3.09 GHz. The small and uniform boron carbide grains and residual carbon with multiple morphologies enhance the interface polarization and electronic polarization in the material, which leads to multiple reflections and losses of the microwave. Additionally, the lattice defects and surface holes caused by Cl, N, and other atoms in chitosan and PVC increase the energy storage sites of the material, which makes the materials obtain excellent microwave absorbing properties. Boron carbides fabricated from an organic carbon source provide a potential for the preparation of high‐temperature resistant absorber.