Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method

Carbon nanotube (CNT) synthesis in flame has enormous potential as an energy-efficient and economical production method compared to the conventional catalytic chemical vapor deposition (CCVD) synthesis process. However, synthesis control remains a great challenge for flame synthesis due to the limit...

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Main Author:	Hamzah, Norikhwan
Format:	Thesis
Language:	English
Published:	2020
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/101926/1/NorikhwanHamzahPSKM2020.pdf
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spelling	my-utm-ep.1019262023-07-25T09:33:06Z Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method 2020 Hamzah, Norikhwan TJ Mechanical engineering and machinery Carbon nanotube (CNT) synthesis in flame has enormous potential as an energy-efficient and economical production method compared to the conventional catalytic chemical vapor deposition (CCVD) synthesis process. However, synthesis control remains a great challenge for flame synthesis due to the limited understanding on the effect of flame inlet condition toward CNT growth region in a heterogeneous flame environment and premature catalyst surface encapsulation by the amorphous carbon layer. The present study formulates a simple, yet accurate method called wirebased macro image analysis (WMA) for thorough growth region identification. The WMA method is employed to investigate the effects of reactant composition and aerodynamics on the spatial distribution of CNT growth region. Besides that, bend wire method is developed to provide cross-sectional analysis of the CNT growth region with focus on the amorphous carbon layer thickness (ACLT) at variable reactant concentration including fuel from 50% to 100% and oxygen from 19% to 27%, with addition of water vapor up to 0.14 mg/sec mass flow rate within the fuel stream. The CNT is synthesized on a 0.4 mm diameter pure nickel wire within the methane diffusion flame with a stainless-steel wire mesh placed on top and water vapor is introduced in a fuel stream using a bubbler mechanism. The CNT growth region is confined within the flame sheet, gradually shifts from flame front to flame centreline as height above the burner increases. The growth region is more sensitive towards the change in the oxygen concentration compared to that of the fuel concentration due to the significant change of flame height caused by the former. A segregation of growth region temperature with temperature difference of 100 ? that is observed between the upstream and downstream growth region is governed by the proximity with respect to the flame sheet. The ACLT reduces in lean flame due to the reduction in excess carbon concentration and the addition of water vapor remarkably reduces ACLT by 17% on average in any combination of inlet conditions due to the water-induced etching and oxidation of amorphous carbon on the catalyst surface. Development of the WMA and bend wire method leads to deeper fundamental understanding of CNT flame synthesis and further enhance possibility of highly efficient and economical CNT production process in the future. 2020 Thesis http://eprints.utm.my/id/eprint/101926/ http://eprints.utm.my/id/eprint/101926/1/NorikhwanHamzahPSKM2020.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:144997 phd doctoral Universiti Teknologi Malaysia Faculty of Engineering - School of Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Hamzah, Norikhwan Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method
description	Carbon nanotube (CNT) synthesis in flame has enormous potential as an energy-efficient and economical production method compared to the conventional catalytic chemical vapor deposition (CCVD) synthesis process. However, synthesis control remains a great challenge for flame synthesis due to the limited understanding on the effect of flame inlet condition toward CNT growth region in a heterogeneous flame environment and premature catalyst surface encapsulation by the amorphous carbon layer. The present study formulates a simple, yet accurate method called wirebased macro image analysis (WMA) for thorough growth region identification. The WMA method is employed to investigate the effects of reactant composition and aerodynamics on the spatial distribution of CNT growth region. Besides that, bend wire method is developed to provide cross-sectional analysis of the CNT growth region with focus on the amorphous carbon layer thickness (ACLT) at variable reactant concentration including fuel from 50% to 100% and oxygen from 19% to 27%, with addition of water vapor up to 0.14 mg/sec mass flow rate within the fuel stream. The CNT is synthesized on a 0.4 mm diameter pure nickel wire within the methane diffusion flame with a stainless-steel wire mesh placed on top and water vapor is introduced in a fuel stream using a bubbler mechanism. The CNT growth region is confined within the flame sheet, gradually shifts from flame front to flame centreline as height above the burner increases. The growth region is more sensitive towards the change in the oxygen concentration compared to that of the fuel concentration due to the significant change of flame height caused by the former. A segregation of growth region temperature with temperature difference of 100 ? that is observed between the upstream and downstream growth region is governed by the proximity with respect to the flame sheet. The ACLT reduces in lean flame due to the reduction in excess carbon concentration and the addition of water vapor remarkably reduces ACLT by 17% on average in any combination of inlet conditions due to the water-induced etching and oxidation of amorphous carbon on the catalyst surface. Development of the WMA and bend wire method leads to deeper fundamental understanding of CNT flame synthesis and further enhance possibility of highly efficient and economical CNT production process in the future.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Hamzah, Norikhwan
author_facet	Hamzah, Norikhwan
author_sort	Hamzah, Norikhwan
title	Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method
title_short	Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method
title_full	Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method
title_fullStr	Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method
title_full_unstemmed	Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method
title_sort	characterization of carbon nanotube growth region in flame using wire-based macro-imaging method
granting_institution	Universiti Teknologi Malaysia
granting_department	Faculty of Engineering - School of Mechanical Engineering
publishDate	2020
url	http://eprints.utm.my/id/eprint/101926/1/NorikhwanHamzahPSKM2020.pdf
_version_	1776100804902518784

Characterization of carbon nanotube growth region in flame using wire-based macro-imaging method

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