氧化锡纳米线自蔓延高温合成及其机理的研究.pdf

太原理工大学 博士学位论文 氧化锡纳米线自蔓延高温合成及其机理的研究 姓名：李俊寿 申请学位级别：博士 专业：@ 指导教师：@ 20090401 太原理工大学博士研究生学位论文 iv 氧化锡纳米线自蔓延高温合成及其机理的研究 摘 要 自蔓延高温合成（Self-propagating High-temperature Synthesis，缩写 SHS）也称燃烧合成（Combustion Synthesis，缩写 CS） ，是一种通过点燃固 -固反应，靠燃烧波的自行蔓延获得陶瓷材料、金属间化合物以及其它先进 材料的重要方法之一与其它方法相比，具有产品纯度高、设备投资少、 生产效率高、工艺简单、可一次合成和烧结等优点本研究以自蔓延高温 合成技术及其基本理论为指导，基于 Cu2O 高温分解的特性，发明了一种批 量制备氧化锡纳米线的新方法——自蔓延高温合成-喷射法（SHS-J） ；发明 了一种孔径在较大范围内可调的氧化铝基多孔陶瓷制备方法——自蔓延高 温合成-发泡法（SHS-F） ；研究了它们的工艺特性和合成机理 1、采用自蔓延高温合成-喷射法制备了氧化锡纳米线研究表明，所制 备的氧化锡纳米线属于金红石结构，直径为 10~150nm，其中多数为 40~60nm，长度为宏观量。

采用组合化学法进行配方设计，确定了 Al+Cu2O+SnO2、 Al+Cu2O+SnO 两种合成体系可获得氧化锡纳米线的成分范 围，实现了氧化锡纳米线的制备以纳米线（包括少量纳米棒和纳米颗粒） 的产量和转化率为标准，筛选了 SHS-J 法合成氧化锡纳米线的最佳体系和 最佳配方， 用 57.8g SnO 可制备 16.6g SnO2纳米线， 转化率最高可达 25.6 % 2、针对 Al+Cu2O+SnOx反应体系探讨了氧化锡纳米线的自蔓延高温合 成机理，具体包括燃烧反应-气化喷射-动态拉伸三个基本过程通过 Al+Cu2O+SnOx的燃烧反应，形成了由 α-Al2O3、Cu2O+SnO2、Cu+Sn 按密 太原理工大学博士研究生学位论文 v 度分层分布的反应熔池；在高温下 Cu2O 分解出氧气，SnO2发生气化并在 自身气体的压力下从 α-Al2O3陶瓷的微孔中喷出；喷出的 SnO2线由于“线 头”的速度远大于“线尾”的速度，使其在空气中发生动态拉伸，最终形 成氧化锡纳米线这种形成机理既不同于常规的 V-L-S、V-S 机理，也不同 于静电纺丝机理 3、 研究了用自蔓延高温合成-发泡法制备多孔陶瓷的造孔机理， 研究发 现， Cu2O 在高温下分解出氧气是影响多孔陶瓷孔径的主要因素， Al2O3/TiB2 多孔陶瓷的平均孔径随着 Cu2O 添加量的增加而增加，弥补了 SHS 法制备 多孔陶瓷孔径难以控制的不足。

研究表明，α-Al2O3/TiB2多孔陶瓷的孔隙率 开始随着 Cu2O 含量增加而增加，但当 Cu2O 含量超过 10%后，随着 Cu2O 含量增加而下降α-Al2O3/TiB2多孔陶瓷的抗压强度则随着孔隙率增加而降 低 4、研究了氧化锡纳米线生成用基材的改进 （1）采用组合化学法进行 配方设计，研究了反应物成分对 α-Al2O3/TiB2多孔陶瓷结构性能的影响，确 定了 Al+B2O3+TiO2体系获得 α-Al2O3/TiB2多孔陶瓷的有效成分范围研究 表明，当 Al:TiO2:B2O3=6:1:3 时，孔隙率最高可达到 86%；当 Al:TiO2:B2O3 =10:3:3 时，抗压强度最高可达到 14.2MPa （2）α-Al2O3/TiB2多孔陶瓷具有 梯度孔洞结构，其中毫米级孔洞呈不规则形状，平均孔径 200~2000µm；直 径为 1~2µm、长度为 5~10µm 的 TiB2晶须位于孔洞表层，纵横交错构成微 米级孔洞；孔洞表层分布着大量蜂窝状的 α-Al2O3结构，孔形呈多边形状， 孔径为 200~300 nm， 孔壁厚度约 50nm 同时还发现了一种三维蜂窝状 Al2O3 球形结构，直径约 500~ 2000nm。

相信上述 TiB2晶须和 α-Al2O3蜂窝状球形 太原理工大学博士研究生学位论文 vi 结构应具有特殊的物理化学性能，有待进一步研究 关键词：氧化锡，氧化铝，自蔓延高温合成，纳米结构，多孔陶瓷 太原理工大学博士研究生学位论文 vii RESEARCH ON THE SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS MECHANISM OF TIN OXIDE NANOWIRES ABSTRACT Self-propagating High-temperature Synthesis (SHS), namely combustion synthesis, is an important method to obtain ceramics, intermetallics and some other advanced materials by means of solid-solid reactions using an igniting system and propagation of a combustion wave. Compared with the other methods, SHS reactions have some merits, such as high purity of products, low energy requirements, simple apparatus, high production efficient, and realizing synthesis and sintering in one step. In this paper, based on the basic theory of self-propagating high-temperature synthesis, a new large-scale synthesis method of rutile SnO2 nanowires, which is called self-propagating high -temperature synthesis jetting(SHS-J), was obtained in terms of decomposition of cuprous oxide; and a method （SHS-F）for preparation porous α-Al2O3/TiB2 composite ceramics, which can control the pore size of porous α-Al2O3/TiB2, was also discussed. 1）The rutile phase SnO2 nanowires have been prepared successfully with Al+Cu2O+SnOx (x=1,2) system by self-propagating high-temperature synthesis 太原理工大学博士研究生学位论文 viii process. The diameters of the nanowires are in the range of 10～150nm, and mainly between 40 and 60nm. Moreover, the lengths of the nanowires are in macroscopic level. The optimum composition of raw materals for x=1 and 2 was determined. A 25.6% percent conversion was realised by combinatorial chemistry using and 19.8g of SnO2 nanowires was obtained from 57.8g of SnO. 2)The SHS forming mechanism of SnO2 nanostructure was discussed for the Al+Cu2O+SnOx system. There are three fundamental processes in the experiment, including combustion reaction, jet-forming and dynamic tension. At first, the fused bath of α-Al2O3, Cu2O+SnO2 and Cu+Sn, which were distributed hierarchically according to their density, was obtained by combustion reaction of Al+Cu2O+SnOx system. Then Cu2O decomposed, O2 was released SnO2 was gasified and jet out through the micro-holes of the α-Al2O3 porous ceramics under itself gas pressure at high temperature; Because the head velocity of the SnO2 line was far higher than its tail velocity，a dynamic tension occurred and SnO nanowires finally formed. The forming mechanism is different from the conventional mechanisms of V-L-S, V-S, and electrostatic spinning. 3) The mechanism of pore formation in porous ceramics prepared by self-propagating synthesis-foaming method was studied. The results show that the oxygen from Cu2O decomposition at high temperature was the main factor influencing the pore size of porous ceramics. The average pore size of Al2O3/TiB2 increased with increasing additive, overcoming the difficulty in 太原理工大学博士研究生学位论文 ix controlling the pore size of porous ceramics by SHS method. However, when the content of Cu2O was above 10%, the porosity of α-Al2O3/TiB2 decreased with the increase of Cu2O content. Moreover, its compressive strength decreased with the increase of its porosity. 4) The influence of reactant composition on the structures and the properties of the porous α-Al2O3/TiB2 ceramics was studied. The effective reactant compos。