溶液燃烧合成纳米铁基材料及性能研究

发布时间：2018-04-13 08:48

本文选题：溶液燃烧合成 + 纳米材料　；参考：《北京科技大学》2017年博士论文

【摘要】：纳米铁基材料具有独特的电、磁、光、热、化学等性能,在能源存储与转换、水处理、环境修复、高效催化、磁性介质等领域有着广泛的应用前景。现有纳米铁基材料的制备方法存在着工艺复杂、成本高、产率低等问题。溶液燃烧合成是近年来快速发展的一种制备纳米材料的新型湿化学方法,具有简便、快捷、成本低、产率高等诸多优点。本论文将溶液燃烧合成应用于纳米铁基材料的制备,研究内容主要包括以下几方面:(1)以硝酸铁为铁源和氧化剂、甘氨酸为燃料、葡萄糖为添加剂,采用一种基于溶液燃烧合成的新方法成功制备出网状多孔α-F2O3纳米片。该方法包含溶液燃烧合成、煅烧和热处理三个简单步骤。首先,溶液燃烧合成片状前驱体,在前驱体中均匀分布着无定形氧化铁和无定形碳;接着,在氩气气氛中将前驱体在500℃下煅烧0.5h,在煅烧产物中,尺寸为5～10nm的过渡相Fe3C纳米颗粒形成,并且均匀地镶嵌在片状碳支持体上;随后,在空气气氛中将锻烧产物在500℃下热处理0.5h,获得网状多孔α-Fe2O3纳米片。在纳米片中,光滑致密的骨架间均匀分布着大量～40nm的圆形单孔以及少量通孔,该网状多孔α-Fe2O3纳米片的比表面积达到71m2/g。提出了热处理过程中该多孔纳米片的形成机制即在热处理过程中多孔纳米片的形成过程主要包括目标相α-Fe2O3纳米颗粒的生成、聚集以及烧结三个阶段。(2)选取甘氨酸-硝酸铁和葡萄糖-甘氨酸-硝酸铁两种燃烧体系合成氧化铁前驱体,随后在氢气气氛中将其还原,获得不同颗粒尺寸的纳米铁粉。深入研究了燃氧比(φ)对溶液燃烧温度、前驱体物相、比表面积和微观形貌的影响以及还原温度对还原产物物相、颗粒尺寸和磁性能的影响。在甘氨酸-硝酸铁燃烧体系中,溶液(φ=1)燃烧温度为574℃,前期体(φ=1)为α-Fe2O3和γ-Fe2O3的混合物,具有高的比表面积(50.8m2/g)和高的孔隙率,其完全还原温度为400℃。该前驱体在400℃还原2h获得的纳米铁粉的颗粒尺寸为～60nm,饱和磁化强度为201.7emu/g,矫顽力为380.6Oe。在葡萄糖-甘氨酸-硝酸铁燃烧体系中,葡萄的加入改变了燃烧反应条件,使反应变得温和可控。该体系的溶液燃烧温度为383℃,合成的前驱体为α-Fe2O3,具有更高的比表面积(75m2/g)和更高的反应活性,其完全还原温度为275℃。在275℃下还原2h获得的纳米铁粉颗粒的尺寸为20～50nm,饱和磁化强度为196.3emu/g,矫顽力为611.4Oe。(3)以硝酸铁为铁源和氧化剂、甘氨酸为燃料、葡萄糖为碳源,采用一种基于溶液燃烧合成的新方法成功制备出片状纳米铁碳复合材料。该方法包含溶液燃烧合成、氢还原两个简单步骤。首先,溶液燃烧合成片状前驱体,在前驱体中均匀分布着无定形氧化铁和无定形碳;随后,在氢气气氛中将前驱体在400℃还原,获得片状纳米铁碳复合材料。该复合材料由纳米铁颗粒和无定形碳组成,并且纳米铁颗粒均匀地镶嵌于片状碳支持体上。400℃还原2h得到铁碳复合材料的纳米铁颗粒尺寸为～20nm,碳含量为23.2wt.%,比表面积为274.9m2/g,饱和磁化强度为145.7emu/g,矫顽力428.1Oe。(4)采用常压烧结和SPS烧结两种方法实现甘氨酸-硝酸铁燃烧体系所制备纳米铁粉的致密化。深入研究了烧结温度对烧结纯铁的致密度、显微组织、力学性能以及磁性能的影响规律。纳米铁粉具有高的烧结活性,800℃常压烧结纯铁的致密度达到97.3%。900～1300℃常压烧结纯铁具有高的磁饱和强度、高的硬度和抗拉强度。600℃SPS烧结纯铁的致密度达到96.1%,并且具有高的硬度(HRC44.5)。
[Abstract]:Nanometer iron-based materials with unique electrical, magnetic, optical, thermal, chemical and other properties, in the energy storage and conversion, water treatment, environmental remediation, efficient catalysis, magnetic media and other fields have a wide application prospect. The traditional preparation method of nano iron material has complex process, high cost and low yield. Solution combustion synthesis is developing rapidly in recent years, the preparation of a new nano material wet chemical method is simple, fast, low cost, high yield and many other advantages. This paper will be applied to nano solution combustion synthesis of iron-based materials preparation, the main research contents include the following aspects: (1) the iron nitrate iron source and oxidant, glycine as a fuel additive, glucose, using a solution combustion method for synthesis of prepared porous reticular alpha -F2O3 nanosheets. Based on this method contains the solution combustion synthesis, calcination and heat treatment three Simple steps. Firstly, solution combustion synthesis of lamellar precursor in precursor dispersed amorphous iron oxide and amorphous carbon; then, in argon atmosphere, calcination precursor body at a temperature below 500 DEG 0.5h in the calcined products, the formation of size 5 ~ 10nm phase transition of Fe3C nanoparticles, and uniformly dispersed in the sheet carbon support; then, in the atmosphere, calcination product at 500 DEG C for heat treatment of 0.5h, obtaining reticulated porous -Fe2O3 nanosheets. Alpha in nano film, smooth and compact framework of uniformly distributed circular single hole large ~ 40nm and a small hole, the reticulated porous alpha -Fe2O3 nanosheets the specific surface area reached 71m2/g. proposed the formation mechanism of the nano porous film in the heat treatment process of the porous heat treatment process in nano sheet forming process includes the goal of alpha phase -Fe2O3 nanoparticles, aggregation and sintering three Stage. (2) selection of glycine iron nitrate and glucose glycine nitrate combustion synthesis system of iron two iron oxide precursor, then the reduction in hydrogen atmosphere, different particle size of nanometer iron powder was studied. The burning oxygen ratio (PHI) solution of combustion temperature, precursor phase, influence the surface area and micro morphology and reduction temperature on the reduction phase of the product, the influence of size and magnetic properties of particles. In the glycine nitrate combustion system of iron in solution (=1) combustion temperature is 574 DEG C, the body (phi =1) is a mixture of alpha -Fe2O3 and gamma -Fe2O3, has high ratio the surface area (50.8m2/g) and high porosity, the reduction temperature of 400 DEG. The particle size of the precursor obtained by reduction of 2H nanometer iron powder at the temperature of 400 DEG C ~ 60NM, saturation magnetization is 201.7emu/g, coercivity of 380.6Oe. in glucose glycine nitrate combustion system of iron in Portugal Also changed with the addition of the combustion reaction conditions, the reaction is mild and controllable. The solution becomes the combustion temperature is 383 DEG C, the synthesized precursor is alpha -Fe2O3, has a higher surface area (75m2/g) and higher reactivity, the complete reduction of the temperature of 275 DEG. Reduction of nanometer iron powder particles 2H at 275 DEG C to the size of 20 ~ 50nm, saturation magnetization is 196.3emu/g, coercivity of 611.4Oe. (3) with iron nitrate as iron source and oxidant, glycine as fuel, glucose as carbon source, using a solution combustion method for synthesis of prepared nano iron carbon composite materials based on the method includes solution combustion synthesis, hydrogen reduction of two simple steps. Firstly, solution combustion synthesis of lamellar precursor in precursor dispersed amorphous iron oxide and amorphous carbon; then, the precursor reduction in hydrogen atmosphere in 400 DEG C, get Nano iron carbon composite materials. The composite material is composed of nano iron particles and amorphous carbon, and iron nano particles are uniformly embedded in the sheet carbon support.400 C 2H reduction iron particle size of nano iron carbon composite materials for ~ 20nm, the carbon content is 23.2wt.%, the specific surface area is 274.9m2/g, saturation magnetization the strength of 145.7emu/g, the coercivity of 428.1Oe. (4) by atmospheric pressure sintering and sintering of SPS two kinds of methods to achieve the glycine nitrate combustion system for densification of iron nano iron powder was studied. The sintering temperature on density of sintered iron, microstructure, mechanical properties and the influence of the magnetic properties of nanometer iron powder has. High sintering activity, 800 DEG C atmospheric density of sintered iron reaches to 1300 DEG 97.3%.900 atmospheric pressure sintered iron with high magnetic saturation strength, high hardness and tensile strength of.600 C SPS density of sintered iron To 96.1%, and have high hardness (HRC44.5).

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB383.1

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