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首页> 外文期刊>Journal of Heat Transfer >Feedstock Diffusion and Decomposition in Aligned Carbon Nanotube Arrays
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Feedstock Diffusion and Decomposition in Aligned Carbon Nanotube Arrays

机译：对齐碳纳米管阵列中的原料扩散和分解

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摘要

Feedstock diffusion and decomposition in the root growth of aligned carbon nanotube (CNT) arrays is discussed. A nondimensional modulus is proposed to differentiate catalyst poisoning controlled growth deceleration from one which is diffusion controlled. It is found that, at present, aligned multiwalled carbon nanotube (MWNT) arrays are usually free of feedstock diffusion resistance. However, for single-walled carbon nanotube (SWNT) arrays, since the intertube distance is much smaller than the mean free path of carbon source (ethanol here), high diffusion resistance in some currently available samples is significantly limiting the growth rate. The method presented here is also able to predict the critical lengths in different chemical vapor deposition (CVD) processes from which CNT arrays begin to meet this diffusion limit, as well as the possible solutions to this diffusion caused growth deceleration. The diffusion of carbon source inside of an array becomes more important when we found ethanol undergoes severe thermal decomposition at the reaction temperature. This means, in a typical alcohol CVD, hydrocarbons and radicals decomposed from ethanol may collide and react with the outer walls of SWNTs before reaching catalyst particles. When flow rate is low and ethanol is thoroughly decomposed, the produced SWNTs contain more soot structures than the SWNTs obtained at higher ethanol flow rate. Understanding the mass transport and reaction inside a SWNT array is helpful to synthesize longer and cleaner SWNTs.
机译：讨论了取向碳纳米管（CNT）阵列根生长中的原料扩散和分解。提出了无量纲模量以区分催化剂中毒控制的生长减速度和扩散控制的减速度。已经发现，目前，对准的多壁碳纳米管（MWNT）阵列通常没有原料扩散阻力。但是，对于单壁碳纳米管（SWNT）阵列，由于管间距离远小于碳源（此处为乙醇）的平均自由程，因此在一些当前可用样品中的高扩散阻力极大地限制了生长速率。此处介绍的方法还能够预测CNT阵列开始满足此扩散极限的不同化学气相沉积（CVD）过程中的临界长度，以及对该扩散引起的生长减速的可能解决方案。当我们发现乙醇在反应温度下经历严重的热分解时，碳源在阵列内部的扩散变得更加重要。这意味着，在典型的醇CVD中，从乙醇中分解出的碳氢化合物和自由基在到达催化剂颗粒之前可能会与SWNT的外壁碰撞并反应。当流速低且乙醇被彻底分解时，与在较高乙醇流速下获得的SWNT相比，生成的SWNT包含更多的烟灰结构。了解SWNT阵列内部的质量传输和反应有助于合成更长更清洁的SWNT。

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  • 来源
    《Journal of Heat Transfer》 |2012年第5期|p.051023.1-051023.4|共4页
  • 作者

    Rong Xiang; Erik Einarsson; Junichiro Shiomi; Shigeo Maruyama;

  • 作者单位

    State Key Laboratory of Optoelectronic Materials and Technologies,School of Physics and Engineering,Sun Yat-Sen University,Guangzhou 510275, China;

    Department of Mechanical Engineering,The University of Tokyo,7-3-1 Hongo, Bunkyo-ku,Tokyo 113-8656,Japan;

    Department of Mechanical Engineering,The University of Tokyo,7-3-1 Hongo, Bunkyo-ku,Tokyo 113-8656,Japan;

    Department of Mechanical Engineering,The University of Tokyo,7-3-1 Hongo, Bunkyo-ku,Tokyo 113-8656,Japan;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    carbon nanotube (CNT); feedstock diffusion; thermal decomposition; growth mechanism;

    机译：碳纳米管（CNT）;原料扩散热分解;生长机制;

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