Preparation, Structure and Properties of Epoxy/Carbonyl Iron Powder Wave-Absorbing Foam for Electromagnetic Shielding

The application of absorbing materials for electromagnetic shielding is becoming extensive, and the use of absorbents is one of the most important points of preparing absorbing foam materials. In this work, epoxy resin was used as the matrix and carbonyl iron powder (CIP) was used as the absorbent, and the structural absorbing foam materials were prepared by the ball mill dispersion method. Scanning electron microscopy showed that the CIP was evenly dispersed in the resin matrix. The foam structures formed at pre-polymerization times of 10 min, 30 min and 50 min were analyzed, and it was found that the cell diameter decreased from 0.47 mm to 0.31 mm with the increase in the pre-polymerization time. The reflectivity of the frontal and reverse sides of the foam gradually tends to be unified at frequencies of 2-18 GHz. When the CIP content increased from 30 wt% to 70 wt%, the cell diameter increased from 0.32 mm to 0.4 mm, and the uniformity of CIP distribution deteriorated. However, with the increase in the CIP content, the absorption properties of the composite materials were enhanced, and the absorption frequency band broadened. When the CIP content reached 70 wt%, the compression strength and modulus of the foam increased to 1.32 MPa and 139.0 MPa, respectively, indicating a strong ability to resist deformation.