三维针刺碳毡增强碳/氮化硼复合材料的力学和介电性能

Mechanical and dielectric properties of 3D needling carbon felt reinforced carbon/boron nitride composites

三维针刺碳毡中碳纤维的排布方式有利于电磁波的吸收。采用碳基体和氮化硼(BN)基体与三维针刺碳毡复合,可望获得耐高温吸波复合材料。本文中采用先驱体浸渗裂解法(PIP)制备多孔三维针刺碳/碳(C/C)复合材料,再利用化学气相渗透法(CVI)将BN引入C/C复合材料中,最终获得了C/C-BN复合材料。研究了CVI时间对三维针刺C/C-BN复合材料微结构、力学性能及介电性能的影响规律。随着CVI时间的增加,C/C-BN的密度增加,孔隙率降低,抗弯强度提高,介电常数增加,介电损耗降低。在CVI时间达160 h后,C/C-BN密度为1.43 g/cm^3,总气孔率为25%,抗弯强度达到82 MPa。

The microstructure of 3D needling felts is beneficial for the wave absorption. Wave absorbing composites with high temperature resistance could be formed by using carbon and boron nitride matrix with 3D needling carbon felts as reinforcement. In this paper, porous 3D needling carbon/carbon composites （C/C） were fabricated by precursor infiltration pyrolysis （PIP）, then C/C-BN composites were fabricated by introducing BN into the porous C/C by using chemical vapor infiltration （CVI）. The effects of CVI time on the microstructures, mechanical properties and dielectric properties of 3D needling C/C-BN were studied. With the increase of CVI time, the density and flexural strength of C/C-BN increase, while the porosity decreases. When CVI time reaches 160 h, C/C-BN attains a density of 1.4a g/cma , a total porosity of 25 %, and a flexural strength of 82 MPa. Because of the decrease of porosity with the increase of CVI time, the dielectric constant of the C/C- BN composite increases and the dielectric loss decreases.