Dielectric and microwave absorption properties of fluoride-doped MWCNT/Si3N4 composite

• Published in: Journal of materials science. Materials in electronics 2020-02, Vol.31 (4), p.2918-2925
• Main Authors: Saleem, Adil, Zhang, Yujun, Gong, Hongyu, Majeed, Muhammad K., Lin, Xiao, Jing, Jie, Sheng, Mingming, Zhao, Cuncai
• Format: Article
• Language: English
• Subjects: Additives; Aluminum fluorides; Characterization and Evaluation of Materials; Chemistry and Materials Science; Complex permittivity; Composite materials; Densification; Dielectric properties; Diffraction patterns; Fluorides; Frequency ranges; Liquid phases; Magnesium fluorides; Materials Science; Microwave absorption; Multi wall carbon nanotubes; Optical and Electronic Materials; Phase transitions; Silicon carbide; Silicon nitride; Superhigh frequencies
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-02836-2

Herein, silicon nitride (Si 3 N 4 ) ceramic reinforced with multi-walled carbon nanotubes (MWCNT) was processed by hot press sintering using fluoride additives (AlF 3 and MgF 2 ). The X-ray diffraction patterns show that a SiC layer is formed owing to the reaction between Si and MWCNT, leading to a good bonding between MWCN and Si 3 N 4 matrix. The microstructural results revealed that the fluoride additives lead to improve the densification and phase transformation through liquid phase mechanism. The effect of various concentrations of MWCNT on dielectric and microwave (MW) absorption properties of MWCNT/Si 3 N 4 composites in a frequency range of 8.2 to 12.4 GHz (X-band) was investigated. The dielectric parameters have revealed that the complex permittivity of MWCNT/Si 3 N 4 composites have also been enhanced with the addition of MWCNT content. Moreover, the MW absorption properties were improved with the addition of MWCNT, and the minimum value of reflection loss ( R L ) was achieved − 8.65 dB (~ 90% absorption), indicating that the MWCNT/Si 3 N 4 composites might exhibit a promising prospect as MW absorber.