Facial synthesis of Al@MnO_2 with enhanced microwave absorption and low infrared emissivity

摘要

The Al@MnO_2 composites were synthesized by flake aluminum powder and potassium permanganate via a facile one-step method. As a multi-band stealth material, the composites have both enhanced microwave absorbing property and low infrared emissivity. We can use XRD, XPS, SEM, and TEM to detect structure and performance, respectively. The microwave absorbing properties and infrared emissivity were investigated by vector network analyzer and dual-band infrared emissometer. It was found that the MnO_2 nanoparticles were anchored on the aluminum sheets densely, and the concentration of MnO_2 nanoparticles had a certain effect on absorption performance and infrared emissivity. As an absorber, with its polarization effect, resonance effect, and good impedance matching, the composite with the filler loading is 60 wt% can perform excellent microwave absorption performance (Chen et al. in Optik (Stuttg) 172:840-846, 2018). The minimum reflection loss reached - 42.93 dB at 12.72 GHz with a thickness of 1.0 mm, and the bandwidth that exceed - 10 dB ranged from 12.08 GHz to 13.36 GHz (Li et al. in J Colloid Interface Sci 507:131-138, 2017). As an infrared stealth material, the composite exhibits low infrared emissivity in the band range of 8-14 μm, which was attributed to the existence constituent of flake aluminum powder. The infrared emissivity reached 0.55 at the lowest, as well as enlarged with the increase of MnO_2 concentration. Therefore, the Al@MnO_2 composites could be a potential superior microwave and infrared compatible stealth material.