Synthesis of carbon nanotubes on carbon fibers by modified chemical vapor deposition
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摘要: 采用一种改进的化学气相沉积法在炭纤维表面制备碳纳米管。为了提高炭纤维表面的润湿性能,炭纤维在浸渍之前先在CVD设备中在真空下973 K的高温处理,然后在硝酸和浓硫酸体积比为3∶1的混合酸中酸处理30 min。而改进的化学气相沉积法关键在于让催化剂的还原步骤和碳纳米管的生长步骤同时进行。这样通过减小过渡金属元素与炭纤维之间的接触时间从而降低了它们之间的相互扩散,在确保了炭纤维本身的力学性能下降程度明显小于用普通化学气相法制备的情况下生长出长且茂密的碳纳米管阵列。另外,经过对工艺参数的优化发现当用乙醇作溶剂,Fe(NO3)3 · 9H2O溶度为100 mmol/L,氢气和碳源气体比值为4/1,而生长时间为30 min时得到最好的碳纳米管阵列。
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关键词:
- 碳纳米管 /
- 炭纤维 /
- 表面 /
- 前处理 /
- 改进的化学气相沉积法
Abstract: Carbon nanotubes (CNTs) were synthesized on carbon fibers by a modified thermal chemical vapor deposition (CVD) method. The fibers were first treated at a temperature of 973 K and then treated by a mixture of sulfur acid and nitric acid with a volume ratio of 1∶3 to improve the dispersion of catalyst precursor Fe(NO3)3 · 9H2O on the surface before impregnation with a catalyst solution. The carbon fibers then underwent simultaneous catalyst reduction and CNT growth to decrease the contact time between the transition metal and the carbon fiber surface, and a uniform and thick CNT forest could be obtained with no significant decrease of the mechanical strength of the carbon fibers compared with those produced by traditional thermal CVD. An in-depth analysis shows that the process parameters have a great influence on the CNT growth rate, such as the type of solvent, concentration of Fe(NO3)3 · 9H2O, the ratio of H2 to C2H2, and the growth time. It was revealed that a better CNT forest could be obtained when the catalyst solvent is ethanol, the Fe concentration is 100 mmol/L, the ratio of H2/C2H2 is 4/1, the temperature is 1 023 K and the growth time is 30 min.-
Key words:
- Carbon nanotubes /
- Carbon fibers /
- Surface /
- Pretreatment /
- Modified CVD method
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