Lightweight Porous Carbon Foams via Pyrolysis of Robust Polyimide Foams for Efficient Broadband Microwave Absorption

The development of lightweight materials with ultrabroadband microwave absorption (MA) performance and excellent mechanical properties is significant for structural stealth electromagnetic wave-absorbing materials. Herein, the polyimide-derived carbon foams (CPIFs) were fabricated through a microsphere foaming method and a carbonization process for obtaining outstanding MA performance and mechanical property. The effects of carbonization temperature and prefoaming temperature on the pore size and MA property were investigated. The absorption bandwidth of CPIFs can reach an ultrabroadband absorption of 14 GHz, covering the whole X and Ku bands and most of the C band. The low-density CPIFs exhibited impressive compressive strength (0.47–0.64 MPa) and thermal insulation property with the thermal conductivity in the range of 0.061–0.104 W/m·K. The CPIFs’ lightweightedness, excellent MA, thermal insulation, and mechanical properties make them suitable to be used as a structural material with great application prospects in the fields of civil and military defense.