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Magnetic and dielectric properties of magneto-dielectric materials consisting of oriented, iron flake filler within a thermoplastic host.

机译：磁电介质的磁性和介电特性，由热塑性主体内的定向铁片状填料组成。

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摘要

Materials that contain both an electric permittivity and magnetic permeability > 1 are currently being investigated for use as substrates to aid in antenna miniaturization. For such applications these materials, called "magneto-dielectrics", need to be low in weight, low in loss, and high in permeability. In order for these materials to be implemented within the large volume of antennas that are produced every year, they must be easy and cost effective to manufacture in bulk quantities.;An experimental procedure for fabricating magneto-dielectric materials based upon flake-like iron inclusions was developed. In order to minimize loss and maximize permeability, thin flakes with a high aspect ratio must be oriented parallel to the magnetic field. A high yield method for fabricating flakes from an iron powder precursor is discussed. Samples consisting of the iron flakes oriented within a low loss thermoplastic host were produced through several common plastics manufacturing techniques. These techniques were evaluated for their ability to orient the flakes within the plane of interest.;The electrical and magnetic properties of the magneto-dielectric samples were studied. The transport properties of permeability, dielectric constant, and loss were found as a function of the filler's aspect ratio, volume fraction, and orientation distribution. It was found that forming iron powder into flakes increases the permeability by reducing the demagnetization factor of the shape. The change to higher aspect ratio filler also increased the dielectric constant and the dielectric loss due to greater instances of inter-particle conduction. Insulating the flakes with a low dielectric coating greatly reduced the dielectric constant and the loss.;The measured composite properties were compared with several existing transport models. The Wu-McCullough model was found to be the most accurate in predicting the transport properties, but only when an accurate description of the microstructure was known. Therefore great effort was applied to precisely identifying microstructure parameters such as flake aspect ratio and orientation.
机译：目前正在研究同时包含介电常数和磁导率均大于1的材料用作基板，以帮助天线小型化。对于此类应用，这些材料称为“磁电介质”，需要重量轻，损耗低，磁导率高。为了使这些材料能够在每年生产的大量天线中实现，它们必须易于制造且经济高效地批量生产。基于片状铁夹杂物制造磁电介质材料的实验程序已开发。为了最大程度地减少损耗并使磁导率最大化，必须将具有高长宽比的细薄片定向为平行于磁场。讨论了由铁粉前体制备薄片的高产率方法。通过几种常见的塑料制造技术生产了由定向在低损耗热塑性主体中的铁片组成的样品。评估了这些技术使薄片在目标平面内取向的能力。;研究了磁电介质样品的电和磁性能。发现渗透率，介电常数和损耗的传输特性与填料的长宽比，体积分数和取向分布有关。已经发现，将铁粉制成薄片可以通过减小形状的退磁系数来提高其磁导率。由于颗粒间传导的更多情况，改变为高深宽比的填料也增加了介电常数和介电损耗。用低介电涂层对薄片进行绝缘大大降低了介电常数和损耗。;将测得的复合性能与几种现有的传输模型进行了比较。 Wu-McCullough模型被发现是最准确的预测传输特性的方法，但是只有在对微观结构的准确描述已知的情况下。因此，人们付出了巨大的努力来精确识别微观结构参数，例如薄片长宽比和取向。

著录项

  • 作者

    Golt, Michael C.;

  • 作者单位

    University of Delaware.;

  • 授予单位 University of Delaware.;
  • 学科 Engineering Materials Science.
  • 学位 M.M.S.E.
  • 年度 2008
  • 页码 150 p.
  • 总页数 150
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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