Broadband absorption of macro pyramid structure based flame retardant absorbers

Flame-retardant materials with good electromagnetic wave absorption play an increasingly important role in Over-the-Air (OTA) tests in microwave anechoic chambers. In this work, carbon nanotubes and ammonium polyphosphate (CNTs@APP) composite were prepared by crosslinking with the silane coupling agent (KH550). The flame retardancy is improved with the increase of APP. However, the microwave absorption performance (MAP) and processing difficulty changed greatly as well. Therefore, magnesium aluminum double-layer metal hydroxide (LDH) was obtained by coprecipitation method and processing into the coating, so as to realize flame retardancy which reaches the limiting oxygen index (LOI) of 24.8% and good MAP at the same time. Then, a high-frequency structure simulator (HFSS TM ) was used to simulate the pyramid model to realize the broadband absorption, and the optimal parameter range was obtained, that is, when the total height of the material is 40 mm, the height of the base accounts for 1/5???1/3, and the tangent of the half top angle is near 1/5, which result in the best MAP. Finally, the broadband absorption of 14.36 GHz (3.64???18 GHz) was realized when the base height is 1/3, and the broadband absorption of 14 GHz (4???18 GHz) can be realized under the condition of large-angle oblique incidence of 0 ?????60 ??. ?? 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

In this study, carbon nanotubes and ammonium polyphosphate composite were prepared and processed into a coating to achieve materials with good electromagnetic wave absorption and flame retardancy. The optimal parameter range for broadband absorption was determined through simulation of a pyramid model. This research is significant for Over-the-Air tests in microwave anechoic chambers.