| 基于高Q腔法测试氮化硅纤维的介电性能 |
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| 引用本文： | 李庆辉,孔维纳,李喆,王少敏,王绍凯,顾轶卓,李敏.基于高Q腔法测试氮化硅纤维的介电性能[J].复合材料学报,2020,37(9):2240-2249. |
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| 作者姓名： | 李庆辉 孔维纳 李喆 王少敏 王绍凯 顾轶卓 李敏 |
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| 作者单位： | 北京航空航天大学 材料科学与工程学院，北京 100191 |
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| 摘 要： | 氮化硅纤维具有优异的耐高温性能和透波能力，是理想的高温透波增强材料。本文对高Q腔法测试陶瓷纤维介电性能的样品制备和测试方法进行了研究和优化。研究发现，介电测试试样中纤维含量应不低于20wt%，含量过低易导致计算所得的纤维介电常数偏低；同时短切纤维的长度主要影响介电测试数据的离散性，由长度不大于1.0 mm的短纤维所制试样质量高，介电测试结果稳定性更佳。对比讨论了Lichtenecker、Bruggeman和Looyenga三种介电混合模型的适用性，最终基于Lichtenecker介电常数对数混合法则计算得到石英纤维的相对介电常数与文献报道数据较一致。分析表明，氮化硅纤维在10 GHz频率下的相对介电常数为4.4，损耗角正切值为0.0005，是优异的低介电高透波材料。同时，表面上浆剂通过改变纤维表面极性特征，对氮化硅纤维介电性能尤其介电损耗产生显著影响。
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| 关 键 词： | 陶瓷纤维 介电性能 高透波材料 高Q腔法 表面极性 |
| 收稿时间： | 2019-10-16 |
Dielectric properties measurements on silicon nitride fiber based on high-Q cavity method |
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| Affiliation: | School of Materials Science and Engineering, Beihang University, Beijing 100191, China |
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| Abstract: | The silicon nitride fiber has excellent high temperature resistance and wave transmission capability, which is an ideal reinforcement using for high-temperature wave-transparent composites. In this paper, preparation and test methods for the dielectric properties of ceramic fibers tested by high-Q cavity method were studied and optimized for continuous ceramic fibers. The study shows that the fiber content in the dielectric test sample should be no less than 20wt%, and less fiber content tended to result in a relatively smaller value of the fiber dielectric constant. Meanwhile, the length of chopped fiber has effect on the repeatability of the fiber dielectric properties. The samples made by the chopped fiber with the length no more than 1.0 mm are of high quality and the resulted fiber dielectric data are more reliable. In terms of data processing, the applicability of three dielectric mixing models of Lichtenecker, Bruggeman and Looyenga was discussed in comparison. Finally, the permittivity of quartz fibers was calculated based on Lichtenecker dielectric constant logarithmic mixing rule, which was consistent with the reported data. It has been found that the silicon nitride fiber has a permittivity of 4.4 and a loss tangent of 0.0005 at 10 GHz, demonstrating excellent low dielectric. Furthermore, it shows that the surface sizing agent has a significant effect on the dielectric properties particularly the loss tangent of the silicon nitride fiber, which is associated with its surface polarity characteristics of the silicon nitride fiber. |
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