Microwave absorption and bending properties of three‐dimensional gradient honeycomb woven composites

Abstract To avoid the narrow absorption bandwidth and delamination in uniform honeycomb composites, three‐dimensional (3D) gradient honeycomb composites were prepared through a vacuum‐assisted resin transfer molding (VARTM) process. The 3D gradient honeycomb woven composite (3D GHWC) was made by using 3D gradient woven fabric with basalt and carbon fibers as reinforcement and epoxy resin mixed with carbon black and carbonyl iron powder as the matrix. For further optimization of the effective absorbing bandwidth and/or reflection loss (RL), especially at a specific incident angle, the type of absorbing agent and gradient honeycomb structure could be altered in the weaving process. The minimum RL value achieved by the 3D GHWC with 18.5‐mm thickness is −47 dB in the C band at a 30° incident angle using an Agilent vector network analyzer. In addition, the bending strength of the 3D GHWC with 18.5‐mm thickness reaches 101.7 MPa by a universal testing machine, which suggests excellent mechanical properties and ultra‐strong environmental adaptability of the 3D GHWC material. This work offers an adjustable method for the fabrication of microwave absorption (MA) composites, showing potential prospects in civilian and military MA applications.