M型永磁铁氧体磁粉及烧结体的制备、结构、形貌及磁性的研究

发布时间：2018-04-13 20:40

本文选题：M型永磁铁氧体 + 熔盐法　；参考：《兰州大学》2015年硕士论文

【摘要】：M型永磁铁氧体作为一种重要的永磁材料被广泛应用到电子行业和重工业中,本文从离子替代和制备方法等方面对M型永磁铁氧体的制备、结构、形貌及磁性进行了一系列的研究,主要涉及的工作有以下几点：1.采用熔盐法制备了Zn-Ti替代BaM磁粉,并研究了Zn-Ti替代量和不同助熔剂对Zn-Ti替代BaM磁粉的影响,我们发现HcJ的改变不只取决于Zn-Ti替代的量,晶粒的直径厚度比也起到很重要的作用；B作为助熔剂的晶粒尺寸比A作为助熔剂时小很多,使HeJ也提高很多,随着预烧温度的升高,B作为助熔剂的晶粒长大不明显,都是在单畴尺寸以下,晶粒形貌呈现出较小的六角形片状,而A作为助熔剂的晶粒明显长大,有些颗粒处于单畴尺寸以上,晶粒形貌呈现出较厚大的六角形块状。2.通过固相反应法制备了La-Co替代的M型铁氧体磁粉,实验结果说明：增加La-Co替代SrM磁粉的铁含量,对晶粒的长大和直径厚度比增大能起到一定的抑制作用,在相同预烧温度下HcJ随着铁含量的增加而逐渐增大；在改变Ca-La-Co替代SrM磁粉的Ca含量的实验中,在相同预烧温度下随着钙含量的增加,晶粒的尺寸逐渐增大,致使HcJ随着钙含量的增加而降低;少量的钡添加到Ca-La-Co系M型铁氧体磁粉中,能起到抑制晶粒长大和减小晶粒的直径厚度比的作用,可以显著的提高HcJ。3.利用改进的陶瓷工艺法分别制备了纯SrM、La-Co替代SrM、Ca-La-Co替代SrM和Ca-La-Co系M型铁氧体四种烧结永磁铁氧体,典型结果分别为：SrM: Br=3.56 kGs, HcJ=2.63 kOe; La-Co-SrM:Br=4.09 kGs, HcJ=3.97 kOe Ca-La-Co-SrM:Br=3.90 kGs, HcJ=5.18 kOe; Ca-La-Co系M型铁氧体：Br-=4.01 kGs,HcJ=4.69 kOe。能看出：La-Co替代可以显著的提高SrM的Hcj, Ca-La-Co系M型铁氧体的HcJ比La-Co-SrM有所提高,Ca-La-Co-SrM更是得到了5.18 Oe的高值,经过离子替代的Br比纯SrM要高,但是Br总体水平并不高,这主要是因为二次细磨的粒度分布不均匀,使取向度无法提高。4.通过对烧结永磁铁氧体的制备工艺进行调节,结果表明：在预烧时添加Co元素的Br比二次球磨时添加高一些,但是预烧时产生的低矫顽力钻铁氧体,使最终烧结体的HcJ降低,并且J的退磁曲线出现斜率较大的陡降现象；二次细磨的时间延长使颗粒尺寸减小,提高HcJ,但是细小颗粒增多造成粒度分布不均匀,降低了Br,继续延长细磨时间能够改善粒度分布情况,提高磁场取向效果,可以在提高HcJ的同时又不会过多的降低Br。5.利用较细的Fe2O3为原料采用固相反应法,能够得到晶粒尺寸小且分布均匀的预烧粉,这种预烧粉能使La-Co替代SrM烧结永磁铁氧体的剩磁Br和内禀矫顽力HcJ同时得到提高,又可以大大减小二次细磨的时间,提高效率,典型的磁性能为：Br=4.28kGs、HcJ=4.30kOe、(BH)max=4.32MGOe。
[Abstract]:M type permanent magnet ferrite, as an important permanent magnet material, has been widely used in electronic industry and heavy industry. In this paper, the preparation and structure of M type permanent magnet ferrite have been studied from the aspects of ion substitution and preparation methods.A series of studies have been carried out on morphology and magnetism, mainly involving the following points: 1. 1.Zn-Ti instead of BaM magnetic powder was prepared by molten salt method. The effects of Zn-Ti substitution amount and different flux on the substitution of Zn-Ti for BaM magnetic powder were studied. We found that the change of HcJ is not only dependent on the amount of Zn-Ti substitution.The grain size of B as flux is much smaller than that of A as flux, which makes HeJ increase a lot. With the increase of temperature, the grain size of B as flux is not obvious.All of them are below the single domain size, and the grain morphology shows a smaller hexagonal shape, while the grain size of A as flux grows obviously. Some grains are larger than single domain size, and the grain morphology shows a thicker hexagonal block.M-type ferrite magnetic powder replaced by La-Co was prepared by solid state reaction. The experimental results show that increasing the iron content of La-Co instead of SrM magnetic powder can inhibit the grain growth and the increase of the ratio of diameter and thickness to a certain extent.In the experiment of changing the Ca content of Ca-La-Co instead of SrM magnetic powder, the grain size increases with the increase of calcium content at the same pre-firing temperature.The addition of a small amount of barium to the Ca-La-Co system M-type ferrite magnetic powder can inhibit grain growth and decrease the ratio of diameter and thickness of grain, and can significantly increase HCJ.3.Four kinds of sintered permanent magnet ferrites were prepared by using the improved ceramic process. The typical results were as follows: Br=3.56 KGs, HcJ=2.63 KOe; La-Co-SrM:Br=4.09 KGs, HcJ=3.97 kOe Ca-La-Co-SrM:Br=3.90 KGs, HcJ=5.18 KOe; Ca-La-Co M ferrite: Br-4.01 KGsHcJ 4.69 kOe.It can be seen that the substitution of% La-Co can significantly improve the HCJ of SrM. The HcJ of M-type ferrite in Ca-La-Co system is higher than that of La-Co-SrM, and the higher value of 5.18 Oe is obtained. The Br replaced by ion is higher than that of pure SrM, but the overall level of Br is not high.This is mainly due to the second fine grinding particle size distribution is not uniform, so that the degree of orientation can not be improved. 4.By adjusting the preparation process of sintered permanent magnet ferrite, the results show that the Br of adding Co element during pre-sintering is higher than that of secondary ball milling, but the low coercivity ferrite produced during pre-sintering reduces the HcJ of the final sintered body.In addition, the demagnetization curve of J has the phenomenon of steep drop with a large slope, and the prolongation of the time of secondary fine grinding reduces the particle size and increases HCJ, but the increase of fine particles results in uneven particle size distribution.With the decrease of Br., the particle size distribution can be improved by prolonging the fine grinding time, and the effect of magnetic field orientation can be improved, and the HcJ can be improved and the Br.5can not be reduced too much at the same time.The pre-fired powder with small grain size and uniform distribution can be obtained by solid state reaction with fine Fe2O3 as raw material. The remanent magnetic remanence Br and intrinsic coercivity HcJ of La-Co instead of SrM sintered permanent magnet ferrite can be improved simultaneously.The time of secondary fine grinding can be greatly reduced, and the efficiency can be improved. The typical magnetic properties are as follows: 1: Br-4.28kGsHcJ (4.30kOE) BHHmax (4.32MGOE).
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM277

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