What is the important factor affecting microwave absorption performance in corncob-derived carbon/Ni composites?

Abstract

Many factors can affect microwave absorption performance, including impedance matching, attenuation constant, electromagnetic (EM) loss capacity, multi-reflection and scattering and so on. In this work, corncob-derived carbon/Ni composites have been chosen to judge which factor has the greatest influence on the EM absorption behaviors, in which the surface area and pore size have been adjusted by the amount of chemical active additive. Closer impedance matching, larger attenuation constant and stronger EM loss capacity result in the good microwave absorbing behaviors of corncob-derived carbon/Ni composites when the mass ratio of KOH: corncob is 1.5. Minimal reflection loss values can reach −50.25 dB at 12 GHz and the effective bandwidth is 2.24 GHz and reflection loss values start be less than −10 dB at 1.2 mm. Through the analysis of morphology, microstructure, surface area and EM properties, it can be concluded that impedance matching is the most important for obtaining good microwave absorption performances, followed by EM loss ability and attenuation constant, and finally the multi-reflection and scattering by surface area.