CNT纸/SiC对称梯度层状复合材料的高温电磁屏蔽性能和介电性能

A single-layer carbon nanotube (CNT) buckypaper densified by phenolic resin and then welded by resin-derived carbon layer by layer was proposed to obtain a CNT buckypaper/SiC laminated graded composite with a thickness of 2.6 mm in this paper. The CNT buckypaper/SiC laminated graded composite consists of 13 structural layers made of CNT buckypaper/SiC composites and 12 interface layers made of expanded graphite-toughened resin-derived carbon, in which the SiC content increases gradually from the center to both ends with symmetrically distribution along thickness. The CNT buckypaper/SiC laminated graded composite has a volume density of 1.65 g/cm³ and an open porosity of 7.25%. High content CNT with uniform dispersion distribution in SiC matrix was obtained at a macroscopic scale. The average total shielding effectiveness of the CNT buckypaper/SiC laminated graded composite at 600℃ (37.19 dB) is higher than that at room temperature (35.00 dB) throughout the X-band. Compared with the shielding performance at room temperature, the reflection coefficient decreases slightly, but the absorption coefficient increases significantly, and the transmission coefficient decreases from 0.0003 to 0.0002 at 600℃, which forecasts a promising prospect of electromagnetic shielding applications, especially of a high-temperature shielding application. The average value throughout the X-band of the imaginary permittivity increases from 114.6 to 149.1, and that of the loss tangent increases from 1.62 to 1.79, respectively, with the increase of temperature from room temperature to 600℃.