多晶铁纤维表面原位氧化及其微波吸收性能

利用气氛退火炉对多晶铁纤维进行表面原位氧化改性, 获得了表面包覆铁氧化物的多晶铁纤维复合结构。采用扫描电镜、X射线衍射仪观察和表征多晶铁纤维表面氧化前后的形貌和物相, 用微波矢量网络分析仪测试样品在8～18 GHz波段的电磁参数。分别以表面氧化改性前后的多晶铁纤维为吸收剂, 制备厚度为1 mm的吸波涂层, 采用弓形法测试涂层在8～18 GHz波段的反射损耗值。结果表明: 多晶铁纤维经表面原位氧化改性后在表面形成较均匀的铁氧化物, 从而能有效降低其复介电常数, 而复磁导率实部与虚部仍保持较高值。表面包覆铁氧化物的多晶铁纤维以20%填充量制得的吸波涂层, 在8～18 GHz频段的反射损耗优于-10 dB的吸收带宽可达4.5 GHz, 峰值达-25.38 dB。

In-situ Surface Oxidation and Microwave Absorbing Properties of Polycrystalline Iron Fibers

Composites of polycrystalline iron fiber/iron oxide were synthesized by in-situ surface oxidation method in the atmosphere annealing furnace. The morphology and phase of the polycrystalline iron fiber before and after surface oxidation were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The vector network analyzer was employed to measure the electromagnetic parameters of the samples at the waveband of 8～18 GHz. Coatings of 1 mm were prepared with polycrystalline iron fibers before and after surface oxidation as absorbent. The reflection loss of the coatings at the waveband of 8～18 GHz was measured by arch method. The results indicate that the surface of polycrystalline iron fiber was coated with uniform iron oxide, which notably reduced the complex permittivity, but the real part and the imaginary part of the complex permeability were still relatively high. The width of the waveband of 8～18 GHz at the reflection loss below -10 dB was up to 4.5 GHz, and the peak value reached to -25.38 dB for the absorbing coating doped with 20% oxidized iron fiber.