کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5432383 | 1508830 | 2017 | 10 صفحه PDF | دانلود رایگان |
The quality of the electrical contact between the specimen and electromagnetic interference (EMI) shielding testing fixture (coaxial cable method) is found to be critical to shielding effectiveness testing. The carbon fiber (CF) mat (0.15-0.42Â mm thick) and carbon nanofiber (CNF) fiber mat (4.4-4.6Â mm thick) are similar in the shielding effectiveness (68-70Â dB), but the former is much superior in the effectiveness per unit thickness (200 vs. 15Â dB/mm), due to the clinginess of the CF mat (resulting from short fiber protrusion) promoting good electrical contact, even at zero specimen-fixture fastening torque. Flexible graphite (0.13-0.38Â mm thick) is superior to CF/CNF mats in both the shielding effectiveness (110Â dB) and shielding effectiveness per unit thickness (560Â dB/mm), partly due to its deformability promoting the electrical contact. For the CF mat, the shielding effectiveness decreases monotonically with increasing fastening torque, due to the increase in the degree of in-plane fiber preferred orientation and the consequent degradation of the electrical contact between the specimen and testing fixture. In contrast, for both CNF mat and flexible graphite, the torque enhances the shielding. The absorption loss per unit thickness reaches 165, 14 and 500Â dB/mm for CF mat, CNF mat and flexible graphite, respectively.
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Journal: Carbon - Volume 117, June 2017, Pages 427-436