【作者】 董红周；

【导师】 郝春成；

【作者基本信息】 青岛科技大学 ， 材料物理与化学， 2010， 硕士

【摘要】 高压直流输电是解决远距离电力传输的研究方向之一,绝缘材料的发展推动了高压直流输电技术的提高。本论文将纳米碳纤维取向分散到聚合物中,并初步研究了材料的介电性能,希望纳米碳纤维的取向分散能够在直流输电电缆中有所应用。论文首先对纳米碳纤维进行表面改性,在纤维表面沉积镍纳米层,实现纳米碳纤维的表面金属化。通过检测发现,改性后的纳米碳纤维表面沉积了一层约8nm的镍层,镍层上附着部分团聚纳米镍颗粒。随着改性中使用的NiCl₂溶液浓度增大,镍层上附着的团聚的纳米镍颗粒越来越多;改性过程中的纤维分散方式对纤维形貌也有影响,超声分散效果比机械搅拌效果好,得到的纤维表面团聚颗粒较少。将表面改性后的纳米碳纤维在磁场的作用下分散到EVA中,通过观察可看到纤维的取向。分析纳米碳纤维/EVA介电谱,取向复合与非取向复合样品的介电性能发生变化。纳米碳纤维掺杂浓度为0.1wt%和0.5wt%时,取向复合材料比非取向复合材料的相对介电常数低,掺杂浓度为1.0wt%和5.0%wt时,取向复合材料比非取向复合材料的相对介电常数高;掺杂浓度为1.0wt%和5.0wt%时,低频区取向复合材料介质损耗因数高于非取向复合材料,高频区取向复合材料介质损耗因数低于非取向复合材料。更多还原

【Abstract】 High-voltage direct current transmission（HVDC）is studied to deal with the long-distance power transmission. And the advanced insulating materials have promoted the development of HVDC. In this paper, the carbon nanofibers（CNFs）doped in polymer were dispersed in orientation,and the dielectric properties were studied. The oriented-dispersion of CNFs aimed to be applied in HVDC cable.Surface metallization of CNFs was obtained by Ni deposition. The characterizations show that Ni coating is about 8nm with small amount of Ni attached to the surface.As the concentration of NiCl₂ rises, Ni nanoparticles adhesion on the surface increases. And dispersion methods also influence the surface morphology of CNFs. Compared with the mechanical stirring, ultrasonic dispersion could make the solution more homogeneous, and leads to less Ni attachment.Oriented CNFs have been observed by microscope after EVA is composited with modified CNFs under the magnetic field. It is known from the analysis of dielectric spectra of CNFs/EVA that the dielectric properties have changed compared with un-oriented CNFs/EVA.When CNFs concentration was 0.1wt% and 0.5wt%, relative permittivity of oriented CNFs/EVA is smaller than that of un-oriented CNFs/EVA. When the concentration rises to 1.0wt% and 5.0wt%, results are completely opposite. The dissipation factor of oriented CNFs/EVA is greater at low frequency and smaller at high frequency than un-oriented CNFs/EVA as CNFs concentration is 1.0wt% and 5.0wt%.更多还原