scholarly journals Investigation on electromagnetic characteristics, microwave absorption, thermal and mechanical properties of ferromagnetic cobalt–polystyrene composites in the X-band (8.4–12.4 GHz)

RSC Advances ◽  
2016 ◽  
Vol 6 (17) ◽  
pp. 13846-13857 ◽  
Author(s):  
Azizurrahaman Ansari ◽  
Mohammad Jaleel Akhtar

The electromagnetic, thermal and mechanical properties of ferromagnetic cobalt–polystyrene composites in the X-band (8.4–12.4 GHz) are investigated in order to explore their usage for wide band microwave absorbers.

2020 ◽  
Author(s):  
Zhaowen Ren ◽  
Wancheng Zhou ◽  
Yuchang Qing ◽  
Shichang Duan ◽  
Qinlong Wen ◽  
...  

Abstract The SiC fibers are essential for designing microwave absorption and mechanical properties of multifunctional composites. In this study, SLF, KD-II and KD-S SiC fibers were used to fabricate SiC f /SiC composites. The SLF SiC fibers are composed by amorphous SiOC. The KD-II and KD-S SiC fibers exhibit higher crystallizations and free carbon content. The conductivity of SLF, KD-II and KD-S SiC fibers are 0.0127, 1.184 and 0.1316 S/cm, respectively. The flexural strength of SLF, KD-II and KD-S SiC f /SiC composites are 147.77, 322.57 and 248.16 MPa, respectively. The microwave absorption property of the SLF SiC f /SiC composites can be obtained over -25 dB with a thickness of 2.3 mm and the effective absorption bandwidth (EAB) below -10 dB reaches 3.72 GHz with the thickness of 2.7 mm. In contrast, the KD-II SiC f /SiC composites only reach -3.6 dB in the whole X band when the thickness varies from 2 to 2.9 mm. KD-S SiC f /SiC composites can be obtained over -9dB with the thickness of 2mm and the EAB below -7 dB reaches 4.12 GHz with a thickness of 2.2 mm. The mechanisms of mechanical, microwave absorption and penitential applications for SiC f /SiC composites are also discussed.


RSC Advances ◽  
2013 ◽  
Vol 3 (34) ◽  
pp. 14590 ◽  
Author(s):  
Xianguo Liu ◽  
Chao Feng ◽  
Siu Wing Or ◽  
Yuping Sun ◽  
Chuangui Jin ◽  
...  

2016 ◽  
Vol 12 (2) ◽  
pp. 4204-4212 ◽  
Author(s):  
Maheshwar Sharon ◽  
Ritesh Vishwakarma ◽  
Abhijeet Rajendra Phatak ◽  
Golap Kalita ◽  
Nallin Sharma ◽  
...  

Corn cob, an agricultural waste, is paralyzed at different temperatures (700oC, 800oC and 900oC). Microwave absorption of carbon in the frequency range of 2 GHz to 8 GHz is reported. Carbon activated  with 5%  nickel nitrate showed more than 90% absorption of microwave in the frequency range from 6 GHz to 8 GHz, while carbon activated  with 10% Nickel nitrate treated corn cob showed 90% absorption  in the frequency range of 2.5 GHz to 5 GHz. Carbon showing the best absorption are characterized by XRD, Raman spectra and SEM . It is suggested that corn cob treatment   alone with KOH did not improve the microwave absorption, whereas treatment along with nickel nitrate improved the absorption property much better. It is proposed that treatment with nickel nitrate helps in creating suitable pores in carbon   which improved the absorption behavior because while treating carbon with 1N HCl helps to leach out nickel creating equivalent amount of pores in the carbon.


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