Single-source-precursor derived multicomponent CNTs/Fe3Si/Fe/SiOCN ceramic nanocomposites: microstructural evolution and excellent electromagnetic wave absorbing properties

Abstract

In the present work, novel single-source-precursors for CNTs/Fe₃Si/Fe/SiOCN ceramic nanocomposites were synthesized by the reaction of poly(methylvinyl) silazane (HTT 1800) with ferric acetylacetonate [Fe(acac)₃] and carboxylic functionalized carbon nanotubes (CNTs-COOH), which were characterized by means of Fourier transform infrared spectra. The microstructure, phase evolution, electromagnetic properties and electromagnetic microwave absorbing (EMA) performance of the as-prepared ceramics were investigated in detail. The results reveal that the introduced CNTs and the in situ formed nanocrystallites, including α-Fe, Fe₃Si, α-Si₃N₄, β-Si₃N₄, Si₂N₂O, and SiC, are dispersed in an amorphous SiOCN matrix after annealing at 900–1500 °C. The obtained ceramic powders mixed with paraffin wax possess a very low minimum reflection coefficient of −65.3 dB and a broad effective absorption bandwidth of 6 GHz (12–18 GHz) with a thickness of 1.6 mm, indicating outstanding EMA performance. This is due to (i) the increase in interfacial polarization caused by the formation of multiple hetero-interfaces and (ii) the synergistic effect of magnetic and dielectric losses. Therefore, the multicomponent CNTs/Fe₃Si/Fe/SiOCN ceramic nanocomposites have promising potential for thin and high-performance EMA materials applied in a harsh environment.