Coal gangue as an efficient absorber for X-band applications

Abstract

Coal mining generates coal gangue (CG), whose poses considerable ecological challenges. Therefore, using CG in the preparation of electromagnetic wave (EMW)-absorbing materials has emerged as a promising approach for its high-value utilization. In this study, CG was dried and ball-milled. The microscopic morphology, element composition, elemental chemical state, and thermal stability of CG were characterized analyses. The EMW absorption performance of CG in the X-band was tested at filling ratios of 10%, 20%, and 40%. The results showed that CG mainly consisted of SiO2, Al2O3, and C. The CG/paraffin absorber exhibited strong reflection loss (RL) at a relatively thin thickness. When the thickness of the CG/paraffin absorber was 4.0 mm, the minimum RL reached − 50.2 dB at 8.8 GHz. The simulation results of the radar cross section showed that the absorbing coating can reduce EMW scattering on a perfectly conductive substrate, which renders it promising as an excellent EMW-absorbing material.