两种连续SiC纤维的高温介电及吸波性能对比

doi:10.15541/jim20170220

摘要/Abstract

摘要：

采用XPS、XRD、Raman光谱等方法分析了两种典型SiC纤维的微观结构, 研究了微观结构对纤维电导性能的影响, 并揭示了其高温介电性能和吸波性能的演变规律, 对高温结构吸波复合材料的研究具有重要意义。研究表明: KD-I SiC纤维表面富碳, 而SLF SiC纤维以Si-C-O结构为主, 前者具有较高的电导率和复介电常数, 从而导致KD-I纤维与空气阻抗匹配差, 而SLF纤维的损耗较小, 因此两者在X波段的室温反射率仅为-3.2 dB和-0.3 dB。KD-I纤维的复介电常数随着温度的升高显著增大, SLF纤维的实部增幅较大而虚部略小, 两者在700℃时的复介电常数分别达到20.9-j25.0和5.0-j0.37, 高温条件下由于阻抗匹配均变差, 吸波性能无明显改善。

关键词: SiC纤维, 微观结构, 电导率, 高温介电性能, 高温吸波性能

Abstract:

Two kinds of SiC fibers with different microstructures were analyzed by XPS, XRD and Raman spectra. The electrical conductivities of the fibers were measured, and their dielectric and microwave absorbing properties at elevated temperatures were investigated. Research results show that KD-I SiC fiber with rich carbon layers possess higher complex permittivities and electrical conductivities than do SLF SiC fiber with Si-C-O phase, resulting in poor impedance match between free space and KD-I fibers. Simultaneously, due to poor dielectric loss of SLF fiber, two fibers display inferior absorbing performance with the reflection loss values of -3.2 dB and -0.3 dB at X band, respectively. With temperatures increasing, ε° and ε? of KD-I fiber sharply increase, while the complex permittivity of SLF fiber display a small increment. Complex permittivities of two fibers are up to 20.9-j25.0 and 5.0-j0.37 at 700℃. Microwave absorbing properties of two fibers degrade at elevated temperatures, mainly ascribed to deterioration of impedance match.

Key words: SiC fibers, microstructure, electrical conductivity, high-temperature dielectric property, high- temperature microwave absorbing property

中图分类号:

TB34

穆阳, 邓佳欣, 李皓, 周万城. 两种连续SiC纤维的高温介电及吸波性能对比[J]. 无机材料学报, 2018, 33(4): 427-433.

MU Yang, DENG Jia-Xin, LI Hao, ZHOU Wan-Cheng. Comparison of High-temperature Dielectric and Microwave Absorbing Property of Two Continuous SiC Fibers[J]. Journal of Inorganic Materials, 2018, 33(4): 427-433.

图/表 11

表1 KD-I和SLF SiC纤维的性能参数

Table 1 Properties of KD-I and SLF SiC fibers

Type	Diameter/ μm	Density/ (g·cm^-3)	Tensile strength/GPa	Young’s modulus/GPa
KD-I	14-16	~2.54	1.8-2.2	150-200
SLF	12-15	2.3-2.5	2.2-2.4	185

图1 (a) KD-I SiC纤维和(b) SLF SiC纤维的表面SEM照片及其(c) EDS分析结果

Fig. 1 Surface SEM images of (a) KD-I SiC fiber, (b) SLF SiC fiber, and (c) the correspoding EDS analysis

图2 (a) KD-I SiC和SLF SiC纤维的XPS全谱图; (b) SLF SiC纤维的Si2p分峰图谱

Fig. 2 (a) XPS survey spectra of KD-I SiC and SLF SiC fibers; (b) Si2p spectra of SLF SiC fiber

图3 (a) KD-I SiC与SLF SiC纤维的XRD图谱及(b)拉曼光谱图

Fig. 3 (a) XRD patterns and (b) Raman spectra of KD-I SiC and SLF SiC fibers

图4 KD-I SiC和SLF SiC纤维的电导率

Fig. 4 Electrical conductivities of KD-I SiC and SLF SiC fibers

图5 SiC纤维的(a)复介电常数和(b)损耗角正切

Fig. 5 (a) Complex permittivity and (b) loss tangent of SiC fiber

图6 厚度均为3.0 mm的KD-I SiC与SLF SiC纤维预制体的(a)计算反射率和(b)特性阻抗

Fig. 6 (a) Calculated reflection loss and (b) input impedance of KD-I SiC and SLF SiC preforms with the thickness of 3.0 mm

图7 SiCf/SiO2复合材料的断面SEM照片

Fig. 7 Fracture surface morphologies of SiCf/SiO2 composites (a) and (b) KD-I SiCf/SiO2; (c) and (d) SLF SiCf/SiO2

图8 KD-I SiC纤维高温复介电常数

Fig. 8 Complex permittivity of KD-I SiC fibers at various temperatures(a) Real part; (b) Imaginary part

图9 SLF SiC纤维高温复介电常数

Fig. 9 Complex permittivity of SLF SiC fibers at various temperatures(a) Real part; (b) Imaginary part

图10 厚度为3.0 mm的KD-I SiC和SLF SiC纤维预制体的(a)反射率, (b)损耗角正切和(c)特性阻抗随温度的变化

Fig. 10 (a) Reflection loss, (b) loss tangent and (c) input impedance vs. frequency of KD-I SiC and SLF SiC preforms with the thickness of 3.0 mm at various temperatures

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