An Investigation of Carbon Nanotube Synthesis: Modelling and Experiments
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Carbon nanotubes (CNTs) possess exceptional mechanical, electrical and thermal properties by virtue of their unique physical structures. In recent decades, continued efforts have been made to develop techniques for producing CNTs on an industrial scale. The floating catalyst chemical vapour deposition (FCCVD) method has been widely accepted as a promising technique for mass production of CNTs. Despite the recent progress in improving the technique, a lack of fundamental understanding of the limiting factors and the underlying mechanisms of CNT synthesis makes it difficult to scale up the production to meet the ever-growing industrial demands. The present study aims to develop numerical and experimental approaches to extend our understanding of CNT synthesis, and ultimately help develop methods for mass production of CNTs.
A multi-phase thermodynamic equilibrium model consisting of C, H, O, Fe and S elements, at stoichiometries and temperatures consistent with CNT synthesis using the FCCVD method was developed. The effects of variable amounts of the different elements, as well as inert species (Ar and N
Carbon nanotubes were produced using a premixed laminar flat flame burner where a H
A 2-D diffusion model was developed to assist the understanding of the flame method. The spatial distributions of mixture fraction, local temperature, and axial velocity of flows were obtained. This model serves as a pivotal that links all the numerical methods developed in the thesis, and has the capability of estimating a spatially-resolved species distribution for the flame synthesis. The present project both numerically and experimentally studied CNT synthesis, and extended our understanding of the fundamental mechanisms, shedding light into possible routes for mass production of CNTs.