Preparation and Microwave Absorbing Properties of Yolk Shell C@C Microspheres

Abstract

As a typical dielectric loss medium, carbon material has always been the most attractive candidate material for microwave absorption because of its characteristic advantages. However, much less attention has been paid to the reasonable design of micro-structure to improve its performance. According to the transmission behavior and loss mechanism of electromagnetic wave, uniform yolk shell C@C microspheres as a new type of microwave absorbers were creatively prepared by "coating-coating-etching". Compared with solid carbon microspheres, the unique micro-structure endows better BET surface and pore volume to the yolk shell C@C microspheres. The microwave absorption performance was tested in the frequency range of 2GHz to 18GHz. As expected, the yolk shell C@C microspheres exhibit excellent reflection loss characteristics, with strong reflection loss (-41.84dB at 9.2GHz) and wide effective absorption bandwidth(7.9~10.2GHz). This good performance is so for indeed better than most pure carbon absorbers reported. The electromagnetic parameters show that the yolk shell structure is conducive to the matching of characteristic impedance and can obtain ideal microwave absorption ability.