ABSTRACT

An electromagnetic wave absorbing material acting from 8.2 to 12.4 GHz (X-band) is fabricated by mixing BN-coated SiC fiber with AlPO₄ matrix, and using multiwalled carbon nanotubes (MWNCTs) as the absorber. The effect of temperature on the microstructure of BN interface is disclosed by XRD and FT-IR characterizations. The crystallinity of BN increased with elevated temperature. The fracture strength of SiC_f/BN/AlPO₄ composites rise from 175 to 350 MPa and the fracture displacement was elevated from 0.25 to 0.7 mm. The increasing complex permittivity of SiC_f/BN/AlPO₄/MWCNTs composites in the temperature range of 25–600 °C is ascribed to the shortened electron polarization-relaxation time and improved electrical conductivity. Attenuation constant and input impedance are chosen to discuss the reflection loss of the composites. Finally, a 4.2 GHz absorbing bandwidth below −8 dB is achieved with 3.1 mm thickness in the range of 25–600 °C.

摘要

通过将 BN 涂层 SiC 纤维与 AlPO ₄基体混合，并使用多壁碳纳米管 (MWNCTs) 作为吸收体，制备了一种作用于 8.2 至 12.4 GHz（X 波段）的电磁波吸收材料。XRD和FT-IR表征揭示了温度对BN界面微观结构的影响。BN 的结晶度随温度升高而增加。SiC _f /BN/AlPO ₄复合材料的断裂强度从175 MPa提高到350 MPa，断裂位移从0.25 mm提高到0.7 mm。SiC _f /BN/AlPO _{4 的}复介电常数增加/MWCNTs 复合材料在 25-600 °C 的温度范围内归因于缩短的电子极化弛豫时间和提高的导电性。选择衰减常数和输入阻抗来讨论复合材料的反射损耗。最后，在 25–600 °C 范围内以 3.1 mm 的厚度实现低于 -8 dB 的 4.2 GHz 吸收带宽。