Temperature dependence of the microwave absorption performance of carbonyl iron powder/boron-modified phenolic resin composite coating

In this paper, the carbonyl iron powder/boron-modified phenolic resin (CIP/B-modified PR) composite coatings were designed and prepared by hot-pressing process. The density, microstructure, mechanical strength and microwave absorption properties of the coatings were investigated by Archimede’s method, scanning electron microscopy, universal mechanical testing machine and vector network analyzer, respectively. Results has demonstrated that the CIP/B-modified PR coatings with 75 wt% CIP give an ultra-strong adhesion strength above 12 MPa and a minimum reflection loss (RL) of −19.8 dB at 9.4 GHz with a thickness of 1.4 mm. In addition, the effective absorption band (RL < −10 dB) of 75 wt% CIP/B-modified PR coating measured at room temperature is fully covered in the X-band when the absorption thickness is only 1.2 mm. Moreover, the CIP/B-modified PR composite coatings can maintain a relatively stable microwave absorption capability in the X-band with a long-term life at high temperature (250 ℃ for 100 h). Therefore, CIP/B-modified PR coatings with an exceptional absorbing performance could be used in the field of high-temperature microwave absorption materials.