A theoretical quantification of the possible improvement in the mechanical properties of carbon nanotube bundles by carbon ion irradiation
A theoretical quantification of the possible improvement in the mechanical properties of carbon nanotube bundles by carbon ion irradiation
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DOI：
10.1016/j.carbon.2012.11.021
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发表时间：
2013-03
期刊：
影响因子：
10.9
通讯作者：
Nathan P. O’Brien;M. A. McCarthy;W. Curtin
中科院分区：
文献类型：
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作者：
Nathan P. O’Brien;M. A. McCarthy;W. Curtin
采用分子动力学方法研究了碳离子辐照对单壁碳纳米管束力学性能的影响。通过形成管间交联而增加的管间剪切和韧性性质与由诱导缺陷引起的拉伸强度降低相平衡。用能量为50- 300 eV/ion，注量为4× 10 ~（13）cm ~（-2）-2× 10 ~（14）cm ~（-2）的碳离子辐照束进行了力学测试。我们发现，与仔细控制的辐照参数，剪切和韧性参数增加了一个数量级，而拉伸性能降低只有30-40%，在真实的碳纳米管纤维与不连续的碳纳米管filaments. The减少将少得多的纳米尺度的界面响应类似的微米尺度的复合材料，其中间隙C原子起着关键作用。这使得C离子沉积成为电子或其他类型离子辐照的有吸引力的选择，因为额外的C原子可以提供所需的间隙原子。在一定的交联密度范围内，界面剪切模量，剪切应力在粘结开始，和脱粘后的摩擦滑动应力都是线性相关的交联密度，使控制设计的纤维剪切性能可行。一种可能的后处理，非常低的能量照射提出愈合孔和部分恢复拉伸强度。
Improvement of single wall carbon nanotube (CNT) bundle mechanical properties through carbon ion irradiation is investigated using molecular dynamics. Increased inter-tube shear and toughness properties through formation of inter-tube cross-links is balanced against decreased tensile strength from induced defects. Bundles irradiated with carbon ions with energy 50–300eV/ion, and fluence between 4×1013cm−2and 2×1014cm−2, are mechanically tested. We find that with careful control of irradiation parameters, shear and toughness parameters increase by an order of magnitude, while tensile properties reduce by only 30–40%; in real CNT fibres with discontinuous CNT filaments the reduction would be much less. The nano-scale interface response resembles that of micro-scale composites, in which interstitial C atoms play a key role. This makes C ion deposition an attractive option over irradiation by electrons or other types of ions, since the extra C atoms can provide the required interstitial atoms. Within a certain cross-link density range, the interface shear modulus, shear stress at bonding onset, and frictional sliding stress after debonding are all linearly related to cross-link density making controlled design of fibre shear properties feasible. A possible post-treatment with very low energy irradiation is proposed for healing holes and partially restoring tensile strength.