以介孔碳纳米管为模板制备钨纳米线及纳米碳化钨的研究

发布时间：2018-02-11 06:21

  本文关键词： 介孔碳纳米管 钨纳米线 化学气相传输 纳米碳化钨　出处：《北京科技大学》2017年博士论文　论文类型：学位论文

【摘要】：钨及钨基材料以其优异的性能在工业、军事、科研等领域占据了重要地位。但是,钨所具有的本征脆性大大制约了其应用,而一维线状纳米钨—钨纳米线(Tungsten Nanowire,Wn)则凭借其所具有的优异性能(较高的弹性模量—225±20 GPa、较高的硬度—6.2±1.7 GPa和较高的抗拉强度—27.5～32.8 GPa)被认为是钨及钨基材料最好的增韧相,并广泛应用于工业制品、军工产品的增强相或电子信息产品的部件等。然而,对钨纳米线而言,虽然研究广泛,制备方法也很多,但是,目前还没有一种可实现其大量、形貌可控且无催化剂参与的制备方法。同时,纳米碳化钨材料作为一种重要的工业催化剂,也很少有制备方法可以实现其形貌与尺寸的高度可控。而介孔碳纳米管(Mesoporous Carbon Nanotubes,mCNTs)具有独特的介孔管壁和中空管腔结构,该结构使其可以通过管壁的介孔将材料吸附入中空管腔内,并束缚材料的生长,进而获得线状形貌的纳米材料。因此,mCNTs可以作为理想模板来制备一维纳米材料。但是,由于纳米碳材料具有本征憎水性,这使mCNTs的应用受到了较大限制。因此,本文从钨纳米线的制备需求出发,以mCNTs为模板,在确保模板结构完整性的前提下对其进行了亲水性修饰研究。在此基础上,系统地研究了 mCNTs的湿化学法填充和偏钨酸铵(AMT)的还原机理,在无催化剂参与的情况下,制备了形貌可控的钨纳米线,并对其作为块体钨增韧相和纳米W2C前驱体的应用做了初步研究,主要包括:(1)在不破坏mCNTs管壁基本结构的前提下,分别采用强酸混合液、稀释硝酸、双氧水以及双氧水与氨水的混合液四种氧化改性试剂对介孔碳纳米管进行了基团可控的亲水性氧化改性,通过引入羧基和羟基等亲水基团,成功地使介孔碳纳米管获得了亲水性;(2)以毛细管作用为基础,通过对AMT水溶液的性质及AMT水溶液对mCNTs的填充进行了系统研究,首次实现了介孔碳纳米管的室温水溶液大量填充,在室温条件下实现了 AMT在介孔碳纳米管内的批量化填充,制得了 AMT纳米棒/介孔碳纳米管(AMTn/C);(3)采用X-射线衍射分析(XRD)和热重-质谱联用分析方法以及场发射扫描电镜(FESEM)设备,详细地研究了 AMTn/C中AMT还原为W的还原反应过程和还原参数对产物形貌的影响,提出了无催化剂参与且形貌可控的钨纳米线生长机理,并实现了钨纳米线的可批量化制备;(4)首次通过烧结制备出了掺杂钨纳米线的块体钨,结果表明钨纳米线在烧结后的钨块材料中仍维持其线状形貌,并且跨越基体晶界,初步性能测试说明钨纳米线可以起到增韧钨基体的作用。(5)分别以钨纳米线/介孔碳纳米管(Wn/C)和钨纳米颗粒/介孔碳纳米管(Wnd/C)为前驱体,通过热处理得到了两种纳米碳化钨材料(W2C纳米棒和WC纳米颗粒),实现了纳米碳化钨的形貌可控制备,且首次制备出了亚稳相W2C的纳米棒。并对所得纳米碳化钨材料的类过氧化物酶特性进行了检测,其中W2C的类过氧化物酶特性检测属于首次,而且结果表明W2C具有优异的催化性能。
[Abstract]:Tungsten and tungsten based materials for its excellent performance in the industrial, military, scientific research and other fields occupy an important position. However, the brittleness of tungsten has greatly restricted its application, and the one-dimensional nanometer tungsten - tungsten nanowires (Tungsten Nanowire, Wn) by virtue of its excellent performance is higher (the elastic modulus of 225 + 20 GPa, higher hardness - 6.2 + 1.7 GPa and higher tensile strength of 27.5 ~ 32.8 GPa) is considered to be toughened tungsten and tungsten based materials are the best, and is widely used in industrial products, enhance military products or electronic information product components. However, the tungsten nanowires, although extensive research, preparation methods are also many, but there is still no one can achieve its large, controllable morphology and preparation method of the catalyst involved. At the same time, nano tungsten carbide materials as an important industrial catalytic agent, little preparation The highly controllable method can achieve its morphology and size. The mesoporous carbon nanotubes (Mesoporous Carbon, Nanotubes, mCNTs) has a hollow cavity wall and pipe structure of mesoporous structure of the unique, so that it can be through the mesoporous wall material adsorption into hollow cavity, and bound material growth, and to obtain the nano materials linear morphology. Therefore, mCNTs can be used as the ideal templates for preparing one-dimensional nano materials. However, due to the carbon nano material has the intrinsic hydrophobicity, which makes the application of mCNTs are limited. Therefore, the preparation of demand starting from tungsten nanowires, using mCNTs as a template and the study of hydrophilic modification in the premise of ensuring the integrity of the template structure. On this basis, systematically studied the filling wet chemical method mCNTs and ammonium metatungstate (AMT) reduction mechanism, in the absence of catalysts involved in the case, the morphology can be prepared Control of tungsten nanowires, and made a preliminary study on the application of block, as the tungsten precursor and toughened nano W2C mainly includes: (1) without damaging the wall of mCNTs basic structure, using mixed acid, dilute nitric acid, hydrogen peroxide and hydrogen peroxide and ammonia water mixture of four kinds of oxidation modified reagents on the mesoporous carbon nanotubes were modified with hydrophilic groups controlled by oxidation, carboxyl and hydroxyl hydrophilic groups, succeeded in making mesoporous carbon nanotubes obtained hydrophilic; (2) by capillary action as the foundation, through to the AMT solution and AMT solution on properties of filled mCNTs systematically, for the first time solution of mesoporous carbon nanotubes filled with lots of room temperature, at room temperature to achieve the AMT in mesoporous carbon nanotubes in mass filling, prepared AMT Nanorods / mesoporous carbon nanotubes (AMTn/C); (3) by X- The X-ray diffraction analysis (XRD) and thermogravimetry mass spectrometry method and field emission scanning electron microscopy (FESEM), a detailed study of the reduction of AMTn/C in AMT for the effect of reduction reaction of W and reduction of parameters on the morphology, the catalyst participate and controllable morphology of tungsten nanowire growth mechanism, and the tungsten nanowires can be batch preparation; (4) first produced by sintering bulk tungsten doped tungsten nanowires, the results show that the linear morphology remains of tungsten block material tungsten nanowires after sintering, and across grain boundaries, the preliminary performance test shows that tungsten nanowires can to the toughening effect. The tungsten matrix (5) respectively with tungsten nanowires / mesoporous carbon nanotubes (Wn/C) and tungsten nanoparticle / mesoporous carbon nanotubes (Wnd/C) as the precursor by heat treatment and obtained two kinds of nano tungsten carbide materials (W2C nanorods and WC nanoparticles), real 鐜颁簡绾崇背纰冲寲閽ㄧ殑褰㈣矊鍙�鎺у埗澶�,涓旈�栨�″埗澶囧嚭浜嗕簹绋崇浉W2C鐨勭撼绫虫��.骞跺�规墸�

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