Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition
Laser Chemical Vapor Deposition (LCVD) has been shown to have great potential for the manufacture of small, complex, two or three dimensional metal and ceramic parts. One of the most promising applications of the technology is in the fabrication of an integrated dispenser cathode assembly. This ap...
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ndltd-GATECH-oai-smartech.gatech.edu-1853-69782013-01-07T20:12:02ZProcess Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor DepositionJohnson, Ryan WilliamCFD modelingThermal modelStructural modelMass transportCarbonMolybdenumBoron nitrideLCVDLaser chemical vapor depositionLasersCathodes Design and constructionChemical vapor depositionLaser Chemical Vapor Deposition (LCVD) has been shown to have great potential for the manufacture of small, complex, two or three dimensional metal and ceramic parts. One of the most promising applications of the technology is in the fabrication of an integrated dispenser cathode assembly. This application requires the deposition of a boron nitridemolybdenum composite structure. In order to realize this structure, work was done to improve the control and understanding of the LCVD process and to determine experimental conditions conducive to the growth of the required materials. A series of carbon fiber and line deposition studies were used to characterize processshape relationships and study the kinetics of carbon LCVD. These studies provided a foundation for the fabrication of the first high aspect ratio multilayered LCVD wall structures. The kinetics studies enabled the formulation of an advanced computational model in the FLUENT CFD package for studying energy transport, mass and momentum transport, and species transport within a forced flow LCVD environment. The model was applied to two different material systems and used to quantify deposition rates and identify ratelimiting regimes. A computational thermalstructural model was also developed using the ANSYS software package to study the thermal stress state within an LCVD deposit during growth. Georgia Techs LCVD system was modified and used to characterize both boron nitride and molybdenum deposition independently. The focus was on understanding the relations among process parameters and deposit shape. Boron nitride was deposited using a B3N3H6-N2 mixture and growth was characterized by sporadic nucleation followed by rapid bulk growth. Molybdenum was deposited from the MoCl5-H2 system and showed slow, but stable growth. Each material was used to grow both fibers and lines. The fabrication of a boron nitridemolybdenum composite was also demonstrated. In sum, this work served to both advance the general science of Laser Chemical Vapor Deposition and to elucidate the practicality of fabricating ceramicmetal composites using the process.Georgia Institute of Technology2005-07-28T18:08:17Z2005-07-28T18:08:17Z2004-12-13Dissertation56284185 bytesapplication/pdfhttp://hdl.handle.net/1853/6978en_US |
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CFD modeling Thermal model Structural model Mass transport Carbon Molybdenum Boron nitride LCVD Laser chemical vapor deposition Lasers Cathodes Design and construction Chemical vapor deposition |
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CFD modeling Thermal model Structural model Mass transport Carbon Molybdenum Boron nitride LCVD Laser chemical vapor deposition Lasers Cathodes Design and construction Chemical vapor deposition Johnson, Ryan William Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition |
description |
Laser Chemical Vapor Deposition (LCVD) has been shown to have great potential for the manufacture of small, complex, two or three dimensional metal and ceramic parts. One of the most promising applications of the technology is in the fabrication of an integrated dispenser cathode assembly. This application requires the deposition of a boron nitridemolybdenum composite structure. In order to realize this structure, work was done to improve the control and understanding of the LCVD process and to determine experimental conditions conducive to the growth of the required materials. A series of carbon fiber and line deposition studies were used to characterize processshape relationships and study the kinetics of carbon LCVD. These studies provided a foundation for the fabrication of the first high aspect ratio multilayered LCVD wall structures. The kinetics studies enabled the formulation of an advanced computational model in the FLUENT CFD package for studying energy transport, mass and momentum transport, and species transport within a forced flow LCVD environment. The model was applied to two different material systems and used to quantify deposition rates and identify ratelimiting regimes. A computational thermalstructural model was also developed using the ANSYS software package to study the thermal stress state within an LCVD deposit during growth. Georgia Techs LCVD system was modified and used to characterize both boron nitride and molybdenum deposition independently. The focus was on understanding the relations among process parameters and deposit shape. Boron nitride was deposited using a B3N3H6-N2 mixture and growth was characterized by sporadic nucleation followed by rapid bulk growth. Molybdenum was deposited from the MoCl5-H2 system and showed slow, but stable growth. Each material was used to grow both fibers and lines. The fabrication of a boron nitridemolybdenum composite was also demonstrated. In sum, this work served to both advance the general science of Laser Chemical Vapor Deposition and to elucidate the practicality of fabricating ceramicmetal composites using the process. |
author |
Johnson, Ryan William |
author_facet |
Johnson, Ryan William |
author_sort |
Johnson, Ryan William |
title |
Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition |
title_short |
Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition |
title_full |
Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition |
title_fullStr |
Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition |
title_full_unstemmed |
Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition |
title_sort |
process development for the manufacture of an integrated dispenser cathode assembly using laser chemical vapor deposition |
publisher |
Georgia Institute of Technology |
publishDate |
2005 |
url |
http://hdl.handle.net/1853/6978 |
work_keys_str_mv |
AT johnsonryanwilliam processdevelopmentforthemanufactureofanintegrateddispensercathodeassemblyusinglaserchemicalvapordeposition |
_version_ |
1716474232012013568 |