A New Type Of Catalyst Allows Carbonyl Iron Powder To Be Coated With Sio2 For Tuned Microwave Absorption

In this work, we prepares a core-shell carbonyl iron powder (CIP) SiO2 binary composite (CIP@SiO2) by sol-gel method, in which L-lysine is firstly used as a catalyst to synthesize CIP@SiO2. The structure, chemical composition and morphology of the obtained composite and its microwave absorption performance are analyzed in detail. The electron microscopy images results show that the surface of the spherical CIP is distributed with an island-shaped connected rough SiO2 shell, which we propose is due to the different bonding modes of SiO2 and CIP surface and discuss it in details. In addition, the thickness of SiO2 can be adjusted by the ratio of reactant amount. The electromagnetic parameters show that the coating of SiO2 greatly improve the impedance matching of original CIP. The minimum reflection loss of CIP@SiO2 under the optimum reaction condition can reach-49.39 dB, and the widest effective absorption bandwidth can reach 7.12 GHz (10.88-18.00 GHz) only at the thickness of 1.5 mm. Its microwave absorption performance is significantly better than that of original CIP. Taken together, core-shell CIP@SiO2 binary composite has great potential as excellent microwave absorbers.