弱氧化辅助的碳纳米管阵列的制备工艺研究
发布时间：2018-10-20 10:25
【摘要】：壁虎优异的爬壁性能来源于其脚掌的精细结构,设计并制备这种具有优异黏附性能的仿壁虎刚毛对爬壁机器人等具有非常重要的意义。碳纳米管具有优异的力学、光学和热学性能等,其尺寸可达纳米级别,成为仿壁虎刚毛的热门材料。本文通过化学气相沉积法可控制备了具有优异黏附性能的碳纳米管阵列,研究了其黏附特性,分析了各工艺参数的影响。具体研究内容如下:(1)在常压环境下,通过CVD法制备了具有不同催化剂基底的碳纳米管阵列,分析了各工艺参数的影响。氢气能够还原催化剂,优化催化剂颗粒形貌和质量,显著影响碳纳米管阵列的质量;沉积时间越长,碳纳米管生长的越高,但是存在限值,并且时间越长杂质和缺陷也会越多。(2)催化剂对碳纳米管阵列的生长起决定性的作用。本文以Fe作为主要的催化剂,因为Fe对C原子有很高的溶解度能够形成FeC3,在高温下C原子在铁内能够快速转移并饱和析出生长碳纳米管。以SiO2/Al2O3为支撑层,Al2O3的多孔状结构能够让铁颗粒的分布均匀,优化熔融状态下细小致密的铁颗粒形成,但Al2O3层过厚则容易造成更多的催化剂扩散损失。致密的SiO2层则能够减少催化剂的损失。(3)在常规低压CVD工艺的基础上通过鼓泡工艺在碳纳米管的生长过程中引入了弱氧化剂H2O。弱氧化剂能够刻蚀催化剂周围的无定形碳,增强催化剂的活性,使碳纳米管能够更长时间的生长。通过分析水蒸气含量的影响我们发现,较少的水能够显著改善碳纳米管的生长,使其长得更高,缺陷更少;但是过多的水由于刻蚀作用强而导致碳纳米管无法生长,因此30 sccm水蒸气(Ar)最为适中。(4)通过黏附力测试装置对聚合物PVS和碳纳米管阵列干黏附材料进行黏附性能测试。测试结果表明,在低压100 torr环境下,以SiO2/Al2O3/Fe=300 nm/20 nm/2 nm为催化剂基底,气体流量比为H2:C2H4:Ar=177:272:734 sccm的CVD工艺制备的碳纳米管阵列具有超强的黏附能力,达到32.9 N/cm2,但是其法向黏附力却很弱。与此相反,聚合物PVS具有强的的法向黏附力,但是其切向黏附力较弱。水辅助法虽然能够制备得到更高的碳纳米管,但是其黏附性能却大大降低。
[Abstract]:The excellent wall climbing performance of gecko comes from the fine structure of its soles. It is very important to design and fabricate the gecko bristles with excellent adhesion performance for the wall climbing robot. Carbon nanotubes (CNTs) have excellent mechanical, optical and thermal properties. In this paper, carbon nanotube arrays with excellent adhesion properties can be controlled by chemical vapor deposition. The adhesion characteristics of carbon nanotubes are studied and the effects of various technological parameters are analyzed. The main contents are as follows: (1) carbon nanotube arrays with different catalyst substrates were prepared by CVD method under atmospheric pressure, and the effects of various process parameters were analyzed. Hydrogen can reduce the catalyst, optimize the morphology and mass of catalyst particles, and significantly affect the quality of carbon nanotube arrays. The longer the deposition time, the higher the growth of carbon nanotubes, but there is a limit value. And the longer the time is, the more impurities and defects will occur. (2) Catalysts play a decisive role in the growth of carbon nanotube arrays. In this paper, Fe is used as the main catalyst, because of the high solubility of Fe to C atom, C atom can be rapidly transferred and saturated to grow carbon nanotubes (CNTs) in iron at high temperature. With SiO2/Al2O3 as the supporting layer, the porous structure of Al2O3 can make the distribution of iron particles uniform, and optimize the formation of fine and dense iron particles in the melting state, but the thickness of Al2O3 layer is easy to cause more diffusion loss of catalyst. The dense SiO2 layer can reduce the catalyst loss. (3) based on the conventional low-pressure CVD process, the weak oxidant H _ 2O was introduced into the growth process of carbon nanotubes by bubbling process. The weak oxidant can etch the amorphous carbon around the catalyst, enhance the activity of the catalyst, and make the carbon nanotubes grow for a longer time. By analyzing the effect of water vapor content, we find that less water can significantly improve the growth of carbon nanotubes, make them grow higher and have fewer defects, but too much water can cause carbon nanotubes to grow because of strong etching. Therefore, 30 sccm water vapor (Ar) is the most suitable. (4) Adhesion properties of polymer PVS and carbon nanotube array dry adhesion materials are tested by means of adhesion force test device. The results show that the carbon nanotube arrays prepared by CVD process with SiO2/Al2O3/Fe=300 nm/20 nm/2 nm as catalyst substrate and gas flow ratio of H2:C2H4:Ar=177:272:734 sccm at low pressure of 100 torr have excellent adhesion ability, up to 32.9 N / cm ~ 2, but the normal adhesion force is very weak. In contrast, polymer PVS has strong normal adhesion, but its tangential adhesion is weak. Although higher carbon nanotubes can be prepared by water assisted method, the adhesion properties of carbon nanotubes are greatly reduced.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TB383.1
本文编号：2282863
[Abstract]:The excellent wall climbing performance of gecko comes from the fine structure of its soles. It is very important to design and fabricate the gecko bristles with excellent adhesion performance for the wall climbing robot. Carbon nanotubes (CNTs) have excellent mechanical, optical and thermal properties. In this paper, carbon nanotube arrays with excellent adhesion properties can be controlled by chemical vapor deposition. The adhesion characteristics of carbon nanotubes are studied and the effects of various technological parameters are analyzed. The main contents are as follows: (1) carbon nanotube arrays with different catalyst substrates were prepared by CVD method under atmospheric pressure, and the effects of various process parameters were analyzed. Hydrogen can reduce the catalyst, optimize the morphology and mass of catalyst particles, and significantly affect the quality of carbon nanotube arrays. The longer the deposition time, the higher the growth of carbon nanotubes, but there is a limit value. And the longer the time is, the more impurities and defects will occur. (2) Catalysts play a decisive role in the growth of carbon nanotube arrays. In this paper, Fe is used as the main catalyst, because of the high solubility of Fe to C atom, C atom can be rapidly transferred and saturated to grow carbon nanotubes (CNTs) in iron at high temperature. With SiO2/Al2O3 as the supporting layer, the porous structure of Al2O3 can make the distribution of iron particles uniform, and optimize the formation of fine and dense iron particles in the melting state, but the thickness of Al2O3 layer is easy to cause more diffusion loss of catalyst. The dense SiO2 layer can reduce the catalyst loss. (3) based on the conventional low-pressure CVD process, the weak oxidant H _ 2O was introduced into the growth process of carbon nanotubes by bubbling process. The weak oxidant can etch the amorphous carbon around the catalyst, enhance the activity of the catalyst, and make the carbon nanotubes grow for a longer time. By analyzing the effect of water vapor content, we find that less water can significantly improve the growth of carbon nanotubes, make them grow higher and have fewer defects, but too much water can cause carbon nanotubes to grow because of strong etching. Therefore, 30 sccm water vapor (Ar) is the most suitable. (4) Adhesion properties of polymer PVS and carbon nanotube array dry adhesion materials are tested by means of adhesion force test device. The results show that the carbon nanotube arrays prepared by CVD process with SiO2/Al2O3/Fe=300 nm/20 nm/2 nm as catalyst substrate and gas flow ratio of H2:C2H4:Ar=177:272:734 sccm at low pressure of 100 torr have excellent adhesion ability, up to 32.9 N / cm ~ 2, but the normal adhesion force is very weak. In contrast, polymer PVS has strong normal adhesion, but its tangential adhesion is weak. Although higher carbon nanotubes can be prepared by water assisted method, the adhesion properties of carbon nanotubes are greatly reduced.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TB383.1
【参考文献】
相关期刊论文 前4条
1 杜鹏东;;仿生学及生物力学研究综述[J];林业机械与木工设备;2013年09期
2 岑海堂;陈五一;;仿生学概念及其演变[J];机械设计;2007年07期
3 孙久荣;戴振东;;仿生学的现状和未来[J];生物物理学报;2007年02期
4 朱平平,杨海洋,何平笙;微制造技术与仿生壁虎腿[J];化学通报;2004年07期
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