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Abstract
Summary
Deposition of carbon nanotubes using spray pyrolysis and plasma enhanced chemical vapor deposition techniques
Fatma Abdel Mouez Elias Mohamed
Carbon nanotubes (CNTs) are a tubular structure made of carbon atoms, having diameter ranges from 1-100 nm and length in micrometers. These properties are primarily determined by composition and are thus relatively easy to control. CNTs have a great potential application due to their low density, and high tensile strength (up to 60 GPa). In addition, the thermal conductivity for multiwall carbon nanotubes (MWCNTs) was found to be >3000 W/mK.
CNTs attract much attention due to their participation in many fields of application such as electrical transport, hydrogen adsorption, catalysis, artificial muscles, mechanical reinforcement, fuel cells, field emission and computers.
Various methods have been developed for the production of CNTs, including arc discharge, pyrolysis, plasma enhanced chemical vapor deposition. Recently, the spray pyrolysis technique has attracted attention due to the possibility of producing CNTs on a commercial scale. The structure of CNTs is dependent on the growth parameters such as the reaction temperature, catalyst, reaction gas, and precursor. This motivates the scientists to study the factors affecting their synthesis. Nowadays, natural precursors such as eucalyptus oil, camphor powder, and palm tree have been used to replace the fossil based materials (like: methane, acetylene, benzene, xylene, toluene, etc.) with alternative renewable resources which are cheaper to produce large amounts of CNTs.
PECVD is a relatively new technique for synthesis CNTs; especially vertically aligned CNTs. Plasma reduces the activation energy needed for the deposition purpose. This means that the growth temperature for fabricating CNTs can be lowered significantly.
The ultimate goal of this research activity is to produce CNTs and study the factors that affect the deposition of carbon nanotubes using spray pyrolysis and plasma enhanced chemical vapor deposition techniques.
After the introductory chapter, comprehensive literature review of the subject is presented in chapter 2. It provides information in a broad range about CNTs. The history and the properties of CNTs are provided. Moreover, this chapter includes the available techniques for synthesizing carbon nanotubes. The surface analysis and characterization of the CNTs are also reviewed in chapter 2.
The third chapter exhibits the various experimental techniques which used throughout the present investigation. In this chapter the spray pyrolysis technique and the plasma enhanced chemical vapor deposition have been used to produce carbon nanotubes and the factors affect their production and the characterizations were also investigated.
The fourth chapter discusses the results. Additionally, the conclusions about the factors influencing the deposition of CNTs via the spray pyrolysis and the plasma enhanced chemical vapor deposition are reported. The chapter is divided into three parts; the first part is about the study and characterization of the CNTs obtained from the method of pyrolysis and a comparison is made between the traditional sources and the natural sources on various substrates such as silicon, glass and anodized aluminum at temperature range from 500 0C to 900 0C. In the second part, the results obtained from the method of plasma enhanced vapor deposition were reported. Furthermore, the effect of growth time at low temperature (500 0C) from 10 to 30 minutes and at a temperature of 700 0C was reported and discussed. The third part includes the preparation of Cu-CNTs composites on low carbon steel using electroless technique and their corrosion properties. The results reveal that the corrosion resistance of Cu-CNTs coating layer increases with increasing CNTs percentage in the composite and the optimum resistance was obtained with steel coated by Cu-23 at. % CNTs.