• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Complex permittivity measurements and mixing laws of ceramic materials and application to microwave processing.
【24h】

Complex permittivity measurements and mixing laws of ceramic materials and application to microwave processing.

机译：陶瓷材料的复介电常数测量和混合规律及其在微波处理中的应用。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The complex permittivity of alumina composites was examined with respect to its dependence on the volume fraction of constituents, microstructure, processing temperature, and processing method. In addition, the effective permittivity of these composites was quantitatively modeled based on the permittivities, volume fractions, and microstructures of the constituents.; The studies focused on the complex permittivity of alumina composites, which contained the lossy additives silicon carbide and copper oxide. Two composite systems were prepared by physically mixing alumina and one of the additives. A third composite system was produced by chemically precipitating copper oxide onto alumina. The two synthesis methods produced composites with different microstructures and complex permittivities. The imaginary part of the complex permittivity was generally larger in the chemically precipitated composites than in the physically mixed composites.; The dependence of the complex permittivities of the composites on volume fraction and microstructure were compared with several algebraic mixing laws and with three dimensional, electrostatic numerical simulations. The algebraic mixing laws do not take into account for the dependence of the imaginary part of the complex permittivity on absorbed water and microstructure, which is affected by composite synthesis. By incorporating general physical characteristics of the composites, the electrostatic simulations were able to accurately predict their permittivity.; Heating some selected alumina composites in conventional and microwave furnaces demonstrate several interesting results. The densification and dielectric proper-ties of the alumina/copper oxide composites varied due to processing temperature. The changes in these properties depended upon preparation method and not on heating method. The density and real part of the complex permittivity of alumina/silicon carbide also varied due to processing temperature and not on heating method. Interestingly, the imaginary part of the complex permittivity of alumina/silicon carbide did depend on heating method. The electrostatic simulations were found to be of limited value in predicting the permittivity when there is a lack of data of the volume fraction or permittivity of minor constituents, which contribute significantly to the overall effective permittivity.; Several dielectric measurement techniques were specifically developed for this research. A stainless steel open-ended coaxial probe accurately measured the complex permittivity of solid dielectric materials up to 1000C and over a broad frequency range of 0.3 to 6 GHz. The probe's insensitivity to low loss materials constrained accurate dielectric measurements of materials with a loss tangent greater than 0.05. A nondestructive resonant cavity was developed to measure the dielectric properties of low loss materials with variable dimensions.
机译：考察了氧化铝复合材料的介电常数与成分的体积分数，微观结构，加工温度和加工方法的关系。此外，这些复合材料的有效介电常数是根据组成的介电常数，体积分数和微观结构进行定量建模的。研究集中于氧化铝复合材料的复介电常数，其中包含有损添加剂碳化硅和氧化铜。通过物理混合氧化铝和一种添加剂来制备两种复合体系。通过将氧化铜化学沉淀到氧化铝上来生产第三种复合体系。两种合成方法产生的复合物具有不同的微观结构和复杂的介电常数。在化学沉淀的复合物中，复介电常数的虚部通常比在物理混合的复合物中大。通过几种代数混合定律和三维静电数值模拟，比较了复合材料的复介电常数对体积分数和微观结构的依赖性。代数混合定律没有考虑复介电常数的虚部对吸收水和微观结构的依赖性，而吸收水和微观结构受复合合成的影响。通过结合复合材料的一般物理特性，静电模拟能够准确预测其介电常数。在常规和微波炉中加热一些选定的氧化铝复合材料显示出一些有趣的结果。氧化铝/氧化铜复合材料的致密化和介电性能因加工温度而异。这些性质的变化取决于制备方法，而不取决于加热方法。氧化铝/碳化硅的介电常数的密度和实部也因加工温度而不是加热方法而变化。有趣的是，氧化铝/碳化硅的复介电常数的虚部确实取决于加热方法。当缺少微量成分的体积分数或介电常数的数据时，静电模拟在预测介电常数方面的价值有限，这对整体有效介电常数有很大贡献。为此研究专门开发了几种介电测量技术。不锈钢开放式同轴探针可精确测量高达1000C且频率范围为0.3至6 GHz的固体介电材料的复介电常数。探头对低损耗材料的不敏感性限制了损耗角正切值大于0.05的材料的精确介电测量。开发了一种无损谐振腔，以测量尺寸可变的低损耗材料的介电性能。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号