纳米级氮化铁的制备及磁性能研究

发布时间：2018-03-31 15:01

本文选题：同步还原氮化法　切入点：分子动力学模拟　出处：《辽宁科技大学》2017年硕士论文

【摘要】：近年来,纳米氮化铁材料受到了人们的广泛关注,不仅磁学性能优异,而且具有极强的抗氧化性和耐磨性,被认为是具有巨大应用潜力的新型磁性纳米材料之一,在机械、航天、化工、电子、冶金、能源、医疗等领域发挥着重要作用。本文使用“一种氮化铁纳米粉体的制备方法及其高压气固反应床”专利技术,采用NH3/H2高压同步还原氮化法,以纳米Fe(OH)3粉体为前驱体,深入研究了反应温度、时间、氨氢比和压强等因素对纳米氮化铁粉体制备和磁性能的影响,并通过X射线衍射(XRD)、透射电镜(TEM)、振动样品磁强计(VSM)和热重(TG)等对产物的物相、成分、形貌、磁性和热稳定性等性能进行了表征及分析。同时,采用分子动力学方法和LAMMPS软件,在原子级别上研究了温度对Fe4N粒径的影响。结果表明,所得粉体的组成主要取决于氨氢比。纳米Fe4N粉体合成的最佳氨氢比为3:1。全氨条件下可以得到单相纳米Fe3N粉体。通过分子动力学模拟和实验相结合,在673 K、2.5 h、0.4 Mpa和氨氢比为3:1的条件下,成功制备出了平均粒径约为35 nm的单相纳米Fe4N粉体。在873 K、5 h、0.6 Mpa和全氨条件下制备出了平均粒径主要集中在45 nm左右的单相纳米Fe3N粉体。TG分析结果表明纳米Fe4N粉体的热稳定性良好。VSM测试结果显示,粒度为35 nm左右的Fe4N粉体的磁滞回线呈现细且窄的形状,其饱和磁化强度Ms=169.80 emu/g,磁性能良好,是较为理想的软磁材料。随着反应温度的升高,纳米Fe4N粉体的饱和磁化强度先上升然后缓慢下降,其中在673 K时达到最大值;内禀矫顽力和磁感应矫顽力持续增加。随着氮化时间的延长,饱和磁化强度先保持平稳,在4 h以后缓慢降低,而内禀矫顽力和磁感应矫顽力则一直上下起伏。随着压强的增加,饱和磁化强度、内禀矫顽力和磁感应矫顽力均出现先增加后减小的现象,其中在0.4 MPa时出现了最大值。各项参数对于剩余磁化强度没有明显的影响。因此,通过精确控制实验过程中的几个参量,可以达到优化纳米Fe4N粉体磁性能的目的。总体来说,该实验方法可以降低反应温度和缩短反应时间,这为进一步深入研究纳米氮化铁粉体材料的制备及其在电磁方面的应用奠定了理论和实验基础,同时对纳米Fe4N粉体的大批量工业化生产与应用具有重要的指导意义。
[Abstract]:In recent years, nanocrystalline iron nitride materials have attracted wide attention. They not only have excellent magnetic properties, but also have strong oxidation resistance and wear resistance. They are considered to be one of the new magnetic nanomaterials with great application potential. The fields of aerospace, chemical industry, electronics, metallurgy, energy and medical treatment play an important role. In this paper, a patent technology of "preparation method of iron nitride nanometer powder and its high pressure gas-solid reaction bed" is used, and NH3/H2 high pressure synchronous reduction nitridation method is used. The effects of reaction temperature, time, ratio of ammonia to hydrogen and pressure on the preparation and magnetic properties of nanometer Fe(OH)3 powders were studied. The phase, composition, morphology, magnetic properties and thermal stability of the products were characterized and analyzed by X-ray diffraction, transmission electron microscope, vibratory sample magnetometer (VSM) and thermogravimetric (TG). Meanwhile, molecular dynamics and LAMMPS software were used to characterize and analyze the properties of the products. The effect of temperature on the particle size of Fe4N was studied at atomic level. The composition of the obtained powder mainly depends on the ratio of ammonia to hydrogen. The optimum ratio of ammonia to hydrogen is 3: 1.The single phase nanometer Fe3N powder can be obtained under the condition of total ammonia. When the ratio of ammonia to hydrogen is 3:1, and the ratio of ammonia to hydrogen is 3:1, The single-phase Fe4N powders with average diameter of about 35 nm were successfully prepared, and the results of TG analysis showed that the average particle size was about 45 nm under the condition of 873 KG 5 h 0. 6 Mpa and total ammonia. The results of TG analysis showed that the nano-sized Fe4N powders were mainly concentrated in the range of 45 nm. VSM test results showed that, The magnetic hysteresis loop of Fe4N powder with particle size of about 35 nm is thin and narrow, and the saturation magnetization of Ms=169.80 EMU / g is good, and it is an ideal soft magnetic material with the increase of reaction temperature. The saturation magnetization of nanocrystalline Fe4N powders increased first and then decreased slowly, and reached the maximum at 673K, and the intrinsic coercivity and magnetic inductive coercivity increased continuously. With the prolongation of nitriding time, the saturation magnetization kept stable first. After 4 h, the intrinsic coercivity and magnetic induced coercivity fluctuated up and down. With the increase of pressure, saturation magnetization, intrinsic coercivity and magnetic induced coercivity increased first and then decreased. The maximum value appears at 0.4 MPa. The parameters have no obvious effect on the residual magnetization. Therefore, by controlling several parameters in the experiment process accurately, the magnetic properties of nano-sized Fe4N powders can be optimized. The experimental method can reduce the reaction temperature and the reaction time, which lays a theoretical and experimental foundation for the further study of the preparation and electromagnetic application of the nanometer iron nitride powder. At the same time, it is of great significance for the industrial production and application of nanometer Fe4N powder.
【学位授予单位】：辽宁科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O614.811;TB383.1

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