本文選題：Ni-Mn-Zn鐵氧體　切入點：核殼復合材料　出處：《陜西科技大學》2014年碩士論文

【摘要】：磁性材料具有微波吸收效率高，，涂層薄等優(yōu)點，而被廣泛的用作微波吸收材料。在磁性材料中，鐵氧體在微波吸收領域占有重要的位置，因為它低廉的成本，吸收效率高的優(yōu)勢。鐵氧體具有高的電阻率，避免金屬導體在高頻下的趨膚效應，同時可以與其它的吸波材料相復合，調節(jié)涂層電磁參數(shù)。但同時鐵氧體又具有強吸收頻帶不夠寬、密度大等不足，從而限制了其在吸波材料領域更為廣泛的用。目前，Mn-Zn和Ni-Zn鐵氧體已有了廣泛的研究，但對于Ni-Mn-Zn鐵氧體的研究卻很少，然而這兩種鐵氧體由于在電磁方面的差別，應用范圍卻是不同的。Ni-Zn鐵氧體通常應用于高頻，由于其高的電阻率，以及相反的渦流損耗，Mn-Zn鐵氧體更適合于低頻由于其低的電阻率和高的磁導率。 本課題采用低溫燃燒法、微波水熱法以及溶膠凝膠自蔓延燃燒法制備名義組成為Ni0.25Mn0.25Zn0.50Fe2O4的鐵氧體，并將Ni0.25Mn0.25Zn0.50Fe2O4鐵氧體與粉煤灰空心微球進行復合，制備出粉煤灰/鐵氧體核殼復合材料。通過差示掃描量熱法(DSC)與熱重法(TG)、X-射線衍射（XRD）、透射電鏡(TEM)、能譜分析（EDS）、掃描電鏡（SEM）、矢量網(wǎng)絡分析儀(VNA)等測試方法，系統(tǒng)地研究了反應過程、物相組成、微觀結構以及吸波性能，分析了不同的反應條件對制備Ni0.25Mn0.25Zn0.5Fe2O4鐵氧體及其復合材料的影響。 低溫燃燒反應制備Ni0.25Mn0.25Zn0.5Fe2O4鐵氧體，結果表明當尿素與金屬硝酸鹽的質量比為1:1，400℃保溫6h的條件下得到純相的Ni0.25Mn0.25Zn0.5Fe2O4鐵氧體，其形貌為不規(guī)則的片狀，晶粒尺寸約為20nm。Ni0.25Mn0.25Zn0.5Fe2O4鐵氧體在涂層厚度為4mm時，小于-10dB的頻帶范圍為5GHz到8GHz，當頻率為7.96GHz時，獲得最小反射率-30.75dB。 微波水熱法制備Ni0.25Mn0.25Zn0.50Fe2O4鐵氧體，當EDTA的添加量為45%時，在反應溫度為160℃以下，保溫2h得到鐵氧體相。當EDTA的質量分數(shù)減少到15%時，在200℃，保溫2h的條件下，制備出含量較高的鐵氧體。在200℃，保溫30min的條件下，添加劑分別為尿素和六次甲基四胺，可以合成純相的鐵氧體，并且添加六次甲基四胺有望制備出鐵氧體空心球。 溶膠凝膠自蔓延燃燒法制備Ni0.25Mn0.25Zn0.50Fe2O4鐵氧體，當pH值為1.0時，經(jīng)過600℃，保溫1h的條件下，合成出純相的Ni0.25Mn0.25Zn0.5Fe2O4鐵氧體。粉煤灰微球經(jīng)過處理，即通過氫氧化超聲清洗，乙二醇表面修飾后，當其質量與鐵氧體的質量比為1/99和0.5/99.5時，制備出了包覆均勻的粉煤灰/鐵氧體核殼結構的復合材料。
[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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