本文選題：同步還原氮化法　切入點：分子動力學(xué)模擬　出處：《遼寧科技大學(xué)》2017年碩士論文

【摘要】：近年來,納米氮化鐵材料受到了人們的廣泛關(guān)注,不僅磁學(xué)性能優(yōu)異,而且具有極強的抗氧化性和耐磨性,被認為是具有巨大應(yīng)用潛力的新型磁性納米材料之一,在機械、航天、化工、電子、冶金、能源、醫(yī)療等領(lǐng)域發(fā)揮著重要作用。本文使用“一種氮化鐵納米粉體的制備方法及其高壓氣固反應(yīng)床”專利技術(shù),采用NH3/H2高壓同步還原氮化法,以納米Fe(OH)3粉體為前驅(qū)體,深入研究了反應(yīng)溫度、時間、氨氫比和壓強等因素對納米氮化鐵粉體制備和磁性能的影響,并通過X射線衍射(XRD)、透射電鏡(TEM)、振動樣品磁強計(VSM)和熱重(TG)等對產(chǎn)物的物相、成分、形貌、磁性和熱穩(wěn)定性等性能進行了表征及分析。同時,采用分子動力學(xué)方法和LAMMPS軟件,在原子級別上研究了溫度對Fe4N粒徑的影響。結(jié)果表明,所得粉體的組成主要取決于氨氫比。納米Fe4N粉體合成的最佳氨氫比為3:1。全氨條件下可以得到單相納米Fe3N粉體。通過分子動力學(xué)模擬和實驗相結(jié)合,在673 K、2.5 h、0.4 Mpa和氨氫比為3:1的條件下,成功制備出了平均粒徑約為35 nm的單相納米Fe4N粉體。在873 K、5 h、0.6 Mpa和全氨條件下制備出了平均粒徑主要集中在45 nm左右的單相納米Fe3N粉體。TG分析結(jié)果表明納米Fe4N粉體的熱穩(wěn)定性良好。VSM測試結(jié)果顯示,粒度為35 nm左右的Fe4N粉體的磁滯回線呈現(xiàn)細且窄的形狀,其飽和磁化強度Ms=169.80 emu/g,磁性能良好,是較為理想的軟磁材料。隨著反應(yīng)溫度的升高,納米Fe4N粉體的飽和磁化強度先上升然后緩慢下降,其中在673 K時達到最大值;內(nèi)稟矯頑力和磁感應(yīng)矯頑力持續(xù)增加。隨著氮化時間的延長,飽和磁化強度先保持平穩(wěn),在4 h以后緩慢降低,而內(nèi)稟矯頑力和磁感應(yīng)矯頑力則一直上下起伏。隨著壓強的增加,飽和磁化強度、內(nèi)稟矯頑力和磁感應(yīng)矯頑力均出現(xiàn)先增加后減小的現(xiàn)象,其中在0.4 MPa時出現(xiàn)了最大值。各項參數(shù)對于剩余磁化強度沒有明顯的影響。因此,通過精確控制實驗過程中的幾個參量,可以達到優(yōu)化納米Fe4N粉體磁性能的目的�？傮w來說,該實驗方法可以降低反應(yīng)溫度和縮短反應(yīng)時間,這為進一步深入研究納米氮化鐵粉體材料的制備及其在電磁方面的應(yīng)用奠定了理論和實驗基礎(chǔ),同時對納米Fe4N粉體的大批量工業(yè)化生產(chǎn)與應(yīng)用具有重要的指導(dǎo)意義。
[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.
【學(xué)位授予單位】：遼寧科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O614.811;TB383.1

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