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以丙烯(C3H6)和氮气(N2)为反应气,用低压化学气相沉积(LPCVD)法在SiC纤维表面制备了热解碳层。考察了碳层厚度对纤维介电性能、反应气中C3H6体积分数对碳层微观结构及纤维介电性能的影响。结果表明,沉积100nm厚碳层后,纤维复介电常数实部由76.4～73.8增加到176.9～174.3,虚部由67.5～66.0增加到214.7～210.2。但碳层厚度进一步增大到200nm后,介电常数的增加不多。当C3H6体积分数由0.6降为0.45时,碳层结构有序化程度降低,晶粒变粗大,纤维介电常数实部由176.9～174.3降为156.4～153.7,虚部由214.7～210.2降为194.5～189.6。
The pyrolytic carbon layer was prepared on the surface of SiC fibers by low pressure chemical vapor deposition (LPCVD) using propylene (C3H6) and nitrogen (N2) as reaction gases. The influence of the carbon layer thickness on the dielectric properties of the fibers, the volume fraction of C3H6 in the reaction gas, the microstructure of the carbon layer and the dielectric properties of the fibers were investigated. The results show that the real part of the complex dielectric constant increases from 76.4 ~ 73.8 to 176.9 ~ 174.3 and the imaginary part increases from 67.5 ~ 66.0 to 214.7 ~ 210.2 after deposition of 100nm thick carbon layer. However, the carbon layer thickness increased to 200nm, the dielectric constant increased little. When the volume fraction of C3H6 is reduced from 0.6 to 0.45, the degree of ordering of the carbon layer decreases and the grains become coarse. The real part of the fiber dielectric constant decreases from 176.9 to 174.3 to 156.4 to 153.7, and the imaginary part decreases from 214.7 to 210.2 to 194.5 ~ 189.6.