Influence of Zn dispersion in SiC on electromagnetic wave absorption characteristics

Abstract

Various materials have been developed for electromagnetic (EM) wave absorption; still, it is a challenge to develop absorbers to get better bandwidth with minimum thickness. To meet the challenge of developing EM wave absorbers with enhanced bandwidth for 8–18 GHz frequency range, in the present work, the effectiveness of metal particle dispersion in the dielectric matrix was studied in the frequency range of 2–18 GHz. For the same, Zn particles were dispersed in SiC. Zn dispersed SiC composites were prepared by dispersing various weight fractions of Zn particles in the SiC matrix using planetary ball mill. A comprehensive effort has been made to elucidate the probable mechanisms governing the characteristic changes in the EM wave absorption behavior of the composite using the concept of skin depth, interfacial polarization, impedance matching, multiple reflections and quarter wavelength destructive interference phenomena. The results indicated that the measured imaginary part of complex permittivity and dielectric loss tangent of Zn dispersed SiC composites exhibit higher value in comparison to pristine SiC. The reflection loss (RL) increases with Zn dispersion till certain loading fractions owing to the good reflecting property of Zn-metal particles and thereafter starts decreasing. Therefore, by changing the loading concentration of Zn particles in SiC, the best EM wave absorption state could be obtained in the 8–18 GHz frequency range. The maximum EM wave absorption behavior is realized for the 6 wt% (equivalent to 2.8 vol%) Zn-dispersion with minimum RL value of −49.45 dB at 15.64 GHz with a thickness of 1.7 mm and the bandwidth corresponding to −10 dB is 4.20 GHz.