Hierarchical porous Ni@boehmite/nickel aluminum oxide flakes with enhanced microwave absorption ability.
In this article, composites consisting of porous Ni cores coated with boehmite/nickel aluminum oxide nanoflakes were successfully prepared by a versatile method. The crystal constituents and shapes of the boehmite/nickel aluminum oxide nanoflakes were strongly influenced by reaction temperature, and their microwave absorption properties were investigated in terms of complex permittivity and permeability. The results reveal that the composites comprising porous Ni cores coated with boehmite/nickel aluminum oxide synthesized at 180 °C present superior absorption properties. The optimal reflection loss is -44.3 dB (>99.99% attenuation) at 14.4 GHz, and the effective absorption (below -10 dB) bandwidth can be monitored in the frequency range of 5.8-18.0 GHz for an absorber with thickness in the range of 1.5-3.5 mm. The high dissipation capability, good impedance match and multiple reflection of the porous flaky structure are responsible for the improvement in microwave absorption. Moreover, a new absorption mechanism was proposed for the porous structure. In this mechanism, the porous structure serves as a spreading container, which attenuates electromagnetic energy by prolonging the travel path and constrains waves in the void space to gradually consume energy. This method paves a new avenue to design porous magnetic-dielectric absorbing materials.
Henan Key Laboratory of Aeronautical Materials and Application Technology, School of Mechatronics Engineering, Zhengzhou University of Aeronautics, Zhengzhou, Henan 450046, China. biao_zhao@zzia.edu.cn zhangray@zzia.edu.cn and Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, M5S 3G8, Canada.
Biao
http://orcid.org/0000-0003-3538-2195
B
Zhao
Henan Key Laboratory of Aeronautical Materials and Application Technology, School of Mechatronics Engineering, Zhengzhou University of Aeronautics, Zhengzhou, Henan 450046, China. biao_zhao@zzia.edu.cn zhangray@zzia.edu.cn.
Junwei
J
Liu
Henan Key Laboratory of Aeronautical Materials and Application Technology, School of Mechatronics Engineering, Zhengzhou University of Aeronautics, Zhengzhou, Henan 450046, China. biao_zhao@zzia.edu.cn zhangray@zzia.edu.cn.
Xiaoqin
X
Guo
School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China.
Wanyu
W
Zhao
Henan Key Laboratory of Aeronautical Materials and Application Technology, School of Mechatronics Engineering, Zhengzhou University of Aeronautics, Zhengzhou, Henan 450046, China. biao_zhao@zzia.edu.cn zhangray@zzia.edu.cn.
Luyang
L
Liang
School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China.
Chao
C
Ma
Henan Key Laboratory of Aeronautical Materials and Application Technology, School of Mechatronics Engineering, Zhengzhou University of Aeronautics, Zhengzhou, Henan 450046, China. biao_zhao@zzia.edu.cn zhangray@zzia.edu.cn.
Rui
http://orcid.org/0000-0002-1943-551X
R
Zhang