| Summary: | 碩士 === 國防大學中正理工學院 === 兵器系統工程研究所 === 94 === This study aimed to develop a feasible process of synthesizing large area aligned carbon nanotubes by chemical vapor deposition technique. The acetylene and a solution of ferrocene dissolved in xylene were used in the CNT growth as the carbon source and catalysts respectively. The effects of processing parameters such as growth temperature, flow rate of acetylene, concentration of metal catalyst, reaction time, and sample position angle on the surface morphology (height and diameter) and microstructure of the obtained carbon nanotubes and characteristics of the obtained carbon nanotubes were analyzed using SEM and TEM techniques. The results showed that growth temperature had profound effect on the growth rate of CNTs. The growth rate reached its peak around 810℃and declined when increasing or decreasing the growth temperature. CNTs of around 526μm in height were obtained at 810℃. As to the supply of carbon source, poor results would be the consequences if the too much or too little carbons were provided. It was found that a flow rate of acetylene around 2.0~2.5sccm gave the best results.
The concentration of metal catalysts was found to have effects on the height and diameter of obtained CNTs. However, the amount of metal catalysts appeared to have reached a saturated state around 5wt.%, any increases of metal catalyst beyond that showed little effect on the obtained results. The samples were placed in various angles relative to the incoming flow in the reactor to investigate the influence of flow field on the CNTs growth. The results showed that samples at 0° (parallel to the flow) provided the best results in the height of CNTs. The TEM micrographs of the CNTs obtained in this study showed that metal catalyst was frequently found at the tip of the CNT and this could be used as an evidence of the presence of top-growth mechanism during the CNT growth.
|
|---|
