Surface structural engineering of carbonyl iron powder for enhancing microwave absorption and anti-oxidation performance

Surface structural engineering is desirable in modifying the surface performance of carbonyl iron powder(CIP)to enhance microwave absorption(MA)and anti-oxidation performance.Herein,the surface shape-dependent CIP absorbers are designed via surface coating with zinc oxide(ZnO)nanoparticles and then a thermal annealing treatment.The morphology of ZnO nanoparticles which can be easily regulated by controlling the annealing temperature ultimately affects the MA performance of CIP coating with ZnO nanoparticles(CIP@ZnO).The core-shell CIP@ZnO particles with cubic cone ZnO nanoparticles exhibit ex-cellent MA performance and thermal stability in comparison to the original CIP.Specifically,the CIP@ZnO annealed at 350 ℃(CIP@ZnO-350)samples which have the cubic cone ZnO nanoparticles exhibit a min-imum reflection loss(RLmin)of-55.35 dB at a thickness of 2.1 mm and a maximum effective absorp-tion bandwidth(EAB)of 7.09 GHz at a thickness of 2.0 mm.In addition,the antioxidant property of the CIP@ZnO composite particles is abruptly enhanced,which breaks the restriction of the application of CIP at high temperatures.The superior MA performance of CIP@ZnO particles with cubic cone ZnO nanoparti-cles comes from the enhancement in surface shape-dependent multiple microwave scattering,interfacial polarization,and electromagnetic-dielectric synergism between ZnO and CIP.