SiC/PPy composite with freeze-cast induced porous structure for efficient microwave absorption.

In this paper, layered porous SiC scaffolds were prepared by freeze casting and sintering, and then followed by loading polypyrrole (PPy) on its surface by in-situ polymerization to obtain porous SiC/PPy composites with different PPy content. The loaded PPy forms a good three-dimensional (3D) conductive network, thus the electrical conductivity and the dielectric loss capability of the sample is improved. Moreover, the porous structure provides more SiC-PPy heterogeneous interfaces for charge accumulation, leading to interfacial polarization and relaxation, further enhancing the microwave absorption performance. Compared with pure SiC particles, SiC/PPy-25 shows an increase in the minimum reflection loss (RL) from −8.64 to −39.1 dB, effective absorption bandwidth (RL < −10 dB) of 4.72 GHz, and comparatively thinner matched thickness of 1.7 mm. We provide a microwave absorption material with simple synthesis, high efficiency and wide application prospect. [ABSTRACT FROM AUTHOR]