Preparation, morphological, and microwave absorbing properties of spongy iron powders/epoxy composites

In this study, spongy iron powders (SIPs) that possess a high specific area (1.57 m2/g) were successfully prepared and used for microwave absorption. The specific area was approximately two times higher than that of commercial carbonyl iron powders (CIPs) (0.73 m2/g). The SIPs were incorporated into epoxy resin, to prepare microwave-absorbing composites. The compositions and reflection loss (R.L.) of the composites made of the CIPs and SIPs were compared at the S, C, X and Ku bands. The results showed that the SIP/epoxy composites are lighter and thinner than those of the CIP/epoxy composites. The relative weight per unit area at the four bands was 8.0, 5.0, 2.7, and 2.0 kg/m2 for the SIP/epoxy composites and 15.3, 7.9, 5.0, and 3.3 kg/m2 for the CIP/epoxy composites. The thickness of the SIP/epoxy composites and CIP/epoxy composites at the four bands was 4.4, 2.5, 1.5, and 1.1 mm and 6.2, 3.0, 2.0, and 1.2 mm, respectively. Compared with the microwave absorption performance, the maximum R.L. of the composites bound with SIPs (14.5, 23.8, 15.9, and 16.4 dB) was larger than those of the composites bound with CIPs (14.2, 11.9, 15.6, and 15.1 dB). The microwave-absorbing composites made of SIPs were lighter, thinner, and exhibited higher microwave absorption performance than did those made of the CIPs in the investigated frequency range.