铁氧体复合材料的制备及性能研究

发布时间：2018-03-28 17:06

  本文选题：Ni-Mn-Zn铁氧体　切入点：核壳复合材料　出处：《陕西科技大学》2014年硕士论文

【摘要】：磁性材料具有微波吸收效率高，，涂层薄等优点，而被广泛的用作微波吸收材料。在磁性材料中，铁氧体在微波吸收领域占有重要的位置，因为它低廉的成本，吸收效率高的优势。铁氧体具有高的电阻率，避免金属导体在高频下的趋肤效应，同时可以与其它的吸波材料相复合，调节涂层电磁参数。但同时铁氧体又具有强吸收频带不够宽、密度大等不足，从而限制了其在吸波材料领域更为广泛的用。目前，Mn-Zn和Ni-Zn铁氧体已有了广泛的研究，但对于Ni-Mn-Zn铁氧体的研究却很少，然而这两种铁氧体由于在电磁方面的差别，应用范围却是不同的。Ni-Zn铁氧体通常应用于高频，由于其高的电阻率，以及相反的涡流损耗，Mn-Zn铁氧体更适合于低频由于其低的电阻率和高的磁导率。 本课题采用低温燃烧法、微波水热法以及溶胶凝胶自蔓延燃烧法制备名义组成为Ni0.25Mn0.25Zn0.50Fe2O4的铁氧体，并将Ni0.25Mn0.25Zn0.50Fe2O4铁氧体与粉煤灰空心微球进行复合，制备出粉煤灰/铁氧体核壳复合材料。通过差示扫描量热法(DSC)与热重法(TG)、X-射线衍射（XRD）、透射电镜(TEM)、能谱分析（EDS）、扫描电镜（SEM）、矢量网络分析仪(VNA)等测试方法，系统地研究了反应过程、物相组成、微观结构以及吸波性能，分析了不同的反应条件对制备Ni0.25Mn0.25Zn0.5Fe2O4铁氧体及其复合材料的影响。 低温燃烧反应制备Ni0.25Mn0.25Zn0.5Fe2O4铁氧体，结果表明当尿素与金属硝酸盐的质量比为1:1，400℃保温6h的条件下得到纯相的Ni0.25Mn0.25Zn0.5Fe2O4铁氧体，其形貌为不规则的片状，晶粒尺寸约为20nm。Ni0.25Mn0.25Zn0.5Fe2O4铁氧体在涂层厚度为4mm时，小于-10dB的频带范围为5GHz到8GHz，当频率为7.96GHz时，获得最小反射率-30.75dB。 微波水热法制备Ni0.25Mn0.25Zn0.50Fe2O4铁氧体，当EDTA的添加量为45%时，在反应温度为160℃以下，保温2h得到铁氧体相。当EDTA的质量分数减少到15%时，在200℃，保温2h的条件下，制备出含量较高的铁氧体。在200℃，保温30min的条件下，添加剂分别为尿素和六次甲基四胺，可以合成纯相的铁氧体，并且添加六次甲基四胺有望制备出铁氧体空心球。 溶胶凝胶自蔓延燃烧法制备Ni0.25Mn0.25Zn0.50Fe2O4铁氧体，当pH值为1.0时，经过600℃，保温1h的条件下，合成出纯相的Ni0.25Mn0.25Zn0.5Fe2O4铁氧体。粉煤灰微球经过处理，即通过氢氧化超声清洗，乙二醇表面修饰后，当其质量与铁氧体的质量比为1/99和0.5/99.5时，制备出了包覆均匀的粉煤灰/铁氧体核壳结构的复合材料。
[Abstract]:Magnetic materials have the advantages of high microwave absorption efficiency and thin coating, and are widely used as microwave absorbing materials. In magnetic materials, ferrite plays an important role in microwave absorption because of its low cost. The advantage of high absorption efficiency. Ferrite has high resistivity, avoids the skin effect of metal conductor at high frequency, and can be combined with other absorbing materials. At the same time, the ferrite has some disadvantages, such as the strong absorption band is not wide enough, and the density is high, which limits its wider use in the field of absorbing materials. At present, Mn-Zn and Ni-Zn ferrite have been widely studied. However, there are few studies on Ni-Mn-Zn ferrite. However, due to the difference in electromagnetic field, the range of application of the two ferrites is different. Ni-Zn ferrite is usually used in high frequency because of its high resistivity. And the contrary eddy current loss Mn-Zn ferrite is more suitable for low frequency due to its low resistivity and high permeability. In this paper, Ni0.25Mn0.25Zn0.50Fe2O4 ferrite was prepared by low temperature combustion method, microwave hydrothermal method and sol-gel self-propagating combustion method, and Ni0.25Mn0.25Zn0.50Fe2O4 ferrite was combined with fly ash hollow microspheres. Fly ash / ferrite core-shell composites were prepared. The reaction process was systematically studied by means of differential scanning calorimetry (DSCS) and thermogravimetry (TGG) X-ray diffraction (XRDX), transmission electron microscopy (TEM), energy dispersive analysis (EDS), scanning electron microscopy (SEM), vector network analyzer (VNA), etc. The effects of different reaction conditions on the preparation of Ni0.25Mn0.25Zn0.5Fe2O4 ferrite and its composites were analyzed. Ni0.25Mn0.25Zn0.5Fe2O4 ferrite was prepared by low temperature combustion reaction. The results showed that pure Ni0.25Mn0.25Zn0.5Fe2O4 ferrite was obtained at 1: 1400 鈩

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