Self-reducing coal-derived carbon/Ni3Fe magnetic composites with frequency-dependent microwave absorption performance

Abstract

Coal-derived carbon/Ni3Fe magnetic composites with frequency dependent microwave absorption performance were prepared at low temperatures (750–850 °C) using coal as the carbon source. The Ni3Fe alloy was successfully formed due to the carbothermal reaction and reducing gas. SEM images indicate the surface becomes rougher and the number of interlayer of the composites increases with increasing reaction temperature. Consistently, high degree of graphitization of the coal-derived carbon was confirmed by using Raman spectroscopy. Specifically, coal-derived carbon/Ni3Fe magnetic composites exhibit frequency-dependent microwave absorption characteristics at 2–18 GHz, that is, as the reaction temperature rises from 750 °C to 850 °C, the minimum reflection loss gradually shifts to low frequencies. Among them, CC/Ni3Fe(800)-0.4 exhibits a minimum reflection loss of −60.76 dB at 16.64 GHz, while the thickness is only 1.28 mm. Such a clean strategy provides experience for the environmental application of coal and microwave absorption. Meanwhile, a lightweight, stable and efficient microwave absorber has been developed.