Дисертації з теми "Metal deposition process"
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Byseke, David, and Alexander Thunell. "Automatic monitoring and control of Laser Metal Deposition Process." Thesis, Högskolan Väst, Avdelningen för Industriell ekonomi, Elektro- och Maskinteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-16745.
Повний текст джерелаHeralic, Almir. "Towards full Automation of Robotized Laser Metal-wire Deposition." Licentiate thesis, University West, Department of Engineering Science, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-2148.
Повний текст джерелаMetal wire deposition by means of robotized laser welding offers great saving potentials, i.e. reduced costs and reduced lead times, in many different applications, such as fabrication of complex components, repair or modification of high-value components, rapid prototyping and low volume production, especially if the process can be automated. Metal deposition is a layered manufacturing technique that builds metal structures by melting metal wire into beads which are deposited side by side and layer upon layer. This thesis presents a system for on-line monitoring and control of robotized laser metal wire deposition (RLMwD). The task is to ensure a stable deposition process with correct geometrical profile of the resulting geometry and sound metallurgical properties. Issues regarding sensor calibration, system identification and control design are discussed. The suggested controller maintains a constant bead height and width throughout the deposition process. It is evaluated through real experiments, however, limited to straight line deposition experiments. Solutions towards a more general controller, i.e. one that can handle different deposition paths, are suggested.
A method is also proposed on how an operator can use different sensor information for process understanding, process development and for manual on-line control. The strategies are evaluated through different deposition tasks and considered materials are tool steel and Ti-6Al-4V. The developed monitoring system enables an operator to control the process at a safe distance from the hazardous laser beam.
The results obtained in this work indicate promising steps towards full automation of the RLMwD process, i.e. without human intervention and for arbitrary deposition paths.
RMS
Denys, Kristof. "Circular motion for robotized metal deposition : verification and implementation." Thesis, Högskolan Väst, Avd för automation och datateknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5469.
Повний текст джерелаYang, Yu. "On-line inspection and thermal properties comparison for laser deposition process." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/Yang_09007dcc803bca12.pdf.
Повний текст джерелаVita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 6, 2007) Includes bibliographical references.
Yarrapareddy, Eswar. "Development of slurry erosion resistant materials by laser-based direct metal deposition process." Ann Arbor, Mich. : ProQuest, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3258777.
Повний текст джерелаTitle from PDF title page (viewed Mar. 18, 2008). Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1898. Adviser: Radovan Kovacevic. Includes bibliographical references.
Segerstark, Andreas. "Laser Metal Deposition using Alloy 718 Powder : Influence of Process Parameters on Material Characteristics." Doctoral thesis, Högskolan Väst, Avdelningen för svetsteknologi (SV), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-11842.
Повний текст джерелаMelo, Leonardo de. "Powder jet particle density distribution analysis and qualification for the laser metal deposition process." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/171441.
Повний текст джерелаMade available in DSpace on 2016-12-13T03:03:04Z (GMT). No. of bitstreams: 1 340514.pdf: 4063742 bytes, checksum: 6a2f911982008b177bc31b52c459c372 (MD5) Previous issue date: 2015
Abstract: The quality of the Laser Metal Deposition process depends on several factors and components. One of them and also one of the most important is the powder jet. Regular monitoring of the different variables involved on the powder jet need to be performed in order to assure the demanded high stability and quality standards of the produced coating layers. This monitoring is done through process monitoring techniques, where the powder jet is illuminated from the side, by a laser line, and recorded by a coaxially aligned camera through the powder feed nozzle. Symmetry, geometry and position of different levels of the powder jet can be analyzed through relevant algorithms. They also provide calculations of the particle density distribution the recorded images. The spatial particle density distribution of the powder jet can be calculated by superimposing individual levels along the jet. The measurement and monitoring principle was successfully tested with various nozzles and powder properties, making it possible to fully characterize a powder jet.
A qualidade do processo de deposição de metais a laser depende de diversos fatores e componentes. Um dos componentes mais importantes é o fluxo de pó metálico. É necessário o monitoramento contínuo das diferentes variáveis e parâmetros que influenciam no fluxo de pó para se garantir os altos padrões de qualidade e estabilidade requeridos nas peças produzidas. Este monitoramento é realizado através de técnicas de controle de processos, onde o fluxo de pó metálico é iluminado lateralmente, por um laser de iluminação em formato de linha, e gravado por uma câmera coaxial ao bocal alimentador de pó. Simetria, geometria e posição de diferentes níveis do fluxo de pó podem ser analisados através de algoritmos relevantes. Tais algoritmos tornam possíveis também cálculos da distribuição das partículas no fluxo, através da sobreposição de imagens de todos os frames gravados no vídeo em cada nível do fluxo de pó. O processo de medição e análise foi testado com sucesso em diferentes bocais alimentadores de pó e com diferentes materiais e parâmetros do fluxo, tornando possível sua caracterização e qualificação.
Kretzschmar, B. S. M., K. Assim, Andrea Preuß, A. Heft, Marcus Korb, Marc Pügner, Thomas Lampke, B. Grünler, and Heinrich Lang. "Cobalt and manganese carboxylates for metal oxide thin film deposition by applying the atmospheric pressure combustion chemical vapour deposition process." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21422.
Повний текст джерелаSegerstark, Andreas. "Additive Manufacturing using Alloy 718 Powder : Influence of Laser Metal Deposition Process Parameters on Microstructural Characteristics." Licentiate thesis, Högskolan Väst, Avd för tillverkningsprocesser, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-8796.
Повний текст джерелаLindell, David. "Process Mapping for Laser Metal Deposition of Wire using Thermal Simulations : A prediction of material transfer stability." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-85474.
Повний текст джерелаAdditiv tillverkning (AT) är en kraftigt växande tillverkningsmetod på grund av sin flexibilitet kring design och möjligheten att skapa komponenter som inte är tillverkningsbara med traditionell avverkande bearbetning. AT kan kraftigt minska tid- och materialåtgång och på så sett minskas kostnader och miljöpåverkan. Införandet av AT i flyg- och rymdindustrin kräver strikt kontroll och förutsägbarhet av processen för att försäkra sig om säkra flygningar. Lasermetalldeponering av tråd är den AT metod som hanteras i denna uppsats. Användandet av tråd som tillsatsmaterial skapar ett potentiellt problem, materialöverföringen från tråden till substratet. Detta kräver att alla processparametrar är i balans för att få en jämn materialöverföring. Är processen inte balanserad syns detta genom materialöverföringsstabiliteterna stubbning och droppning. Stubbning uppkommer då energin som tillförs på tråden är för låg och droppning uppkommer då energin som tillförs är för hög jämfört med vad som krävs för en stabil process. Dessa två fenomen minskar möjligheterna för en kontrollerbar och stabil tillverkning. På grund av detta har användandet utav termiska simuleringar för att prediktera materialöverföringsstabiliteten för lasermetalldeponering av tråd med Waspaloy som deponeringsmaterial undersökts. Det har visat sig vara möjligt att prediktera materialöverföringsstabiliteten med användning av termiska simuleringar och kriterier baserat på tidigare experimentell data. Kriteriet för stubbning kontrolleras om en slutförd simulering resulterar i en tråd som når under smältan. För droppning finns två fungerande kriterier, förhållandet mellan svetshöjd och penetrationsdjup om verktygshöjden är konstant, sker förändringar i verktygshöjden är det dimensionslös ”slenderness” talet ett bättre kriterium. Genom att använda dessa kriterier är det möjligt att kvalitativt kartlägga processfönstret och skapa en bättre förståelse för förhållandet mellan verktygshöjden och den deponerade tvärsnittsarean.
Williams, Joseph James. "Surface reactions of zinc vapour with steel relevant to the Zn-55%Al-1.5%Si hot dip metal coating process." Faculty of Engineering, 2005. http://ro.uow.edu.au/theses/395.
Повний текст джерелаCho, Soon. "Real-Time In-Situ Chemical Sensing in AlGaN/GaN Metal-Organic Chemical Vapor Deposition Processes for Advanced Process Control." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1798.
Повний текст джерелаThesis research directed by: Material Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Säger, Florian. "A Feasibility Study of an Automated Repair Process using Laser Metal Deposition (LMD) with a Machine Integrated Component Measuring Solutio." Thesis, KTH, Industriell produktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-248022.
Повний текст джерелаTillverkare har börjat se stora möjligheter i att reparera slitna eller skadade komponenter som ett sätt att spara resurser, så som råmaterial och energi. Med den besparingen minskar kostnaderna och vinsten kan således maximeras. Reparation möjliggör även återanvändning av komponenter, vilket förlänger komponentens livslängd och leder till förbättrade hållbarhetsåtgärder. Dock tillämpas reparation inte i någon stor utsträckning i nuläget, främst eftersom kostnaderna för reparation överstiger kostnaderna för att köpa en ny komponent. En av de största kostnaderna för att reparera en metallkomponent är att identifiera och kvantifiera slitna eller skadade områden med hjälp av olika externa mätsystem, som är en väldigt arbetsintensiv process. En automatiserad mätprocess skulle minska avsökningskostnaden avsevärt och således reducera den totala kostnaden för komponenten. För att möjliggöra en automatiserad reparationsprocess i en enda maskinlösning är det en förutsättning att en mätanordning ingår i maskinhöljet. Därför har olika mätningslösningar utvärderats med avseende på användbarhet i "TRUMPF TruLaser Cell 3000 Series", vilket är en maskin som använder Laser Metall Deposition-teknik (LMD-teknik) för att skriva ut och svetsa metall på en definierad yta. En teoretisk analys av olika lösningar har utförts, där den teoretiskt mest lämpliga lösningen validerades genom att appliceras till maskinen. Valideringen genererade en modell av ytan av en testkomponent. Sedan utfördes en automatiserad, målrelaterad jämförelse med ett specialiserat CAM-program baserat på modellresultatet, för att bestämma möjligheten att upptäcka slitna områden. Genom att verifiera förmågan att upptäcka slitna områden samt genomförandet av en lyckad reparation kan grunden för en helt automatiserad reparationsprocess bevisas som möjlig i en enda maskinlösning.
Das reparieren von abgenutzten oder beschädigten Komponenten wird immer attraktiver für Hersteller. Es ermöglicht es Ressourcen einzusparen wie beispielsweise Rohmaterial und Energie, was die Lebenszeit einer Komponente verlängert und damit die Nachhaltigkeit verbessert. Allerdings ist Reparieren nach wie vor nicht weit verbreitet, hauptsächlich dadurch bedingt, dass die Reparaturkosten die Kosten für eine neue Komponente übersteigen. Einer der größten Kostenfaktoren des reparieren einer Metallkomponente ist der Arbeitsintensive Teil der Identifizierung und Quantifizierung des abgenutzten oder beschädigten Bereichs mit verschiedensten externen Vermessung Systemen. Ein automatisierter Vermessungsprozess würde die Kosten signifikant reduzieren und neue Applikationen ermöglichen. Das automatisieren der gesamte Prozesskette – in einer Single-Maschinenlösung – erfordert, dass eine Messeinrichtung im Bearbeitungsraum der Maschine angebracht wird. Dafür werden verschiedene Lösungen nach Anwendbarkeit an der Trumpf Laser Cell 3000 Serie hin beurteilt. Eine Maschine, welche Laser Metal Deposition (LMD) als Technologie anwendet um Material auf Oberflächen aufzubringen. Nach einer theoretischen Analyse verschiedener Lösungen wird die beste Lösung va durch anbringen an die Maschine validiert. Bei der Validierung wird ein Oberflächenmodel erzeugt. Das Ergebnis wird dann genutzt um die Fähigkeit zu belegen, dass beschädigte Stellen, durch einen Soll-Ist-Vergleich in einem speziellen CAM Programm, automatisch detektiert werden können. Basierend auf diesem Beleg und mit dem Ergebnis eine Komponente erfolgreich reparieren zu können, gilt die These eines automatisierten Reparaturprozesses in einer Single-Maschinenlösung als beweisen.
Ju, Wentao. "Experimental Investigation of the Epitaxial Lateral Overgrowth of Gallium Nitride and Simulation of Gallium Nitride Metalorganic Chemical Vapor Deposition Process." Ohio : Ohio University, 2003. http://www.ohiolink.edu/etd/view.cgi?ohiou1050589636.
Повний текст джерелаMascart, Monique. "Mise en suspension de poudres métalliques en vue de leur application par roll-coat analyse structurale des revêtements obtenus." Valenciennes, 1997. https://ged.uphf.fr/nuxeo/site/esupversions/d0ebab09-ade0-42e4-93b2-f4cf273386f9.
Повний текст джерелаApicella, Fernandez Sergio. "Surface energy modification of metal oxide to enhance electron injection in light-emitting devices : charge balance in hybrid OLEDs and OLETs." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-25097.
Повний текст джерелаHocquette, Disdier Hélène. "Etude structurale de revetement de surface amorphe métallique élaboré par chalumeau plasma." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10016.
Повний текст джерелаCherkaoui, Mohammed. "Elaboration par electrolyse en courant pulse de revetements d'alliages ni-cu et ni-mo : etude de leurs proprietes." Paris 6, 1987. http://www.theses.fr/1987PA066306.
Повний текст джерелаSchunemann, Esteban. "Paste deposition modelling : deconstructing the additive manufacturing process : development of novel multi-material tools and techniques for craft practitioners." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/13803.
Повний текст джерелаConti, Alfredo. "Tecniche della manifattura additiva - applicazioni in ambito aeronautico e aerospaziale." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13306/.
Повний текст джерелаAntonysamy, Alphons Anandaraj. "Microstructure, texture and mechanical property evolution during additive manufacturing of Ti6Al4V alloy for aerospace applications." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/microstructure-texture-and-mechanical-property-evolution-during-additive-manufacturing-of-ti6al4v-alloy-for-aerospace-applications(03c4d403-822a-4bfd-a0f8-ef49eb65e7a0).html.
Повний текст джерела陳宜呈. "A Study Defect On Metal Deposition Process." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/5e3sby.
Повний текст джерелаOlivas, John Daniel. "Surface study of process contamination of plasma spray metal deposition process." Thesis, 1996. http://hdl.handle.net/1911/16985.
Повний текст джерелаChen, Tin-Chi, and 陳亭棋. "Advanced Process Control of Metal Sputter Deposition Using Time Series Analysis." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/02207222123974896201.
Повний текст джерела中華大學
機械與航太工程研究所
93
In this study, we propose a new method to forecast and control the deposition rate of the sputter process by the time series analysis. In order to let the process model consist with the real process anytime, the time series model is fitted by the history data of the sputter process and then the parameters of the process model are updated whenever new measurements are obtained. The simulation results demonstrate that the performance of the proposed method is better than EWMA and DEWMA methods that are adopted in semiconductor processes.
Chen, Ren-Jie, and 陳仁杰. "Molecular Dynamics Simulation of Sputter-Deposition Metal Films and High Temperature Reflow Process." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/55943194448032856819.
Повний текст джерела國立臺灣大學
應用力學研究所
90
The purposes of this thesis are two fold. First, the molecular dynamics (MD) simulation is used to investigate the influence of process parameters on metal thin film morphology and trench-filling morphology in the damascene process. The MD simulation adopts a two dimensional deposition model and uses Lennard-Jones Potential to represent the intermolecular force acting between Cu atoms. The Gear’s predictor-corrector algorithm is used to calculate the trajectories of atoms. A constant substrate temperature is assumed. The rescaling technique is utilized to model the energy absorbed by the substrate due to the impact of incident atoms. The morphologies of films for different physical parameters, such as temperature, incident energy, deposition rate and high temperature reflow process are discussed. It is found that temperature and incident energy effect play a similar role and with increasing temperature or incident energy, the void percentage and root mean square roughness are decreasing. Meanwhile, there exists an optimal region of deposition rate for an incident energy. Reflow process is achieved by the annealing procedure, the heating up and then cooling down the trench rapidly, to drive the copper diffusion and remedy the void defect. Secondary is to improve the computational efficiency of MD simulation. We treat the calculation of interactions which is the most time-consuming part by using distributed computing based on the Message Passing Interface (MPI). In our result, distributed computing is able to reduce the complexity from O(N2) to O(N2/p) on a p-processor system for N particles and achieve a linear speedup result.
YAO, YING-JU, and 姚映如. "Parametric Optimization of Metal Word Line Tungsten Deposition Process by Using Taguchi Method." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/58062788004606669169.
Повний текст джерела逢甲大學
資訊電機工程碩士在職專班
99
This study has successfully applied the Taguchi method by using data produced by L12 orthogonal array experiment; and by applying Taguchi''s analysis of variance in the film deposition process of the tungsten metal word line (mWL W DEP-Metal Word Line Tungsten Deposition), its process parameters are optimized with the best combination of changes to improve the yield and thus the amount of production. Based on the complement table and ANOVA table of defect errors and the thickness variation, it can clearly determine the process parameters to impact tungsten metal word line thin film deposition as the most important nucleation temperature(℃), Silane(SiH4) ventilation temperature(℃), silane(SiH4) ventilation seconds(sec), film thickness uniformity (%), resistance uniformity(%), and the wafer surface defects (> 0.5um). For tungster metal word line thin film deposition, this study choose the best process parameters to run an batch of LOT for observing yield. The results yield significantly and enhance the foundry, The experiment average error combination result of plant A using the Taguchi method is still not as good as the standard wafer of technology parent company. However the number of defects has been controlled within 10, and so, it is still to achieve the purpose of improving the yield.
Huang, Wen-Yi, and 黃文藝. "An Investigation of the Metal Deposition Process with the Compensation of Substrate Position Effect." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/96146966587384222058.
Повний текст джерела正修科技大學
機電工程研究所
97
As study on the density of metal film on substrate is considered in this investigation. There are material characteristic and reaction magnetic field issue during metal films deposition(Sputtering), and there has stress issue after the metal film deposited upon the substrate surface, to reduce this stress issue can more effectively improve the deformation of substrate and density of metal film. This study is creating a metal film deposition system for substrate application with normal metal material. The sputtering source is 3 inch sputter gun where from Jun-San Tech Co. Ltd. in this system, and cylindrical chamber with CF series flange and expansibility design, thus there has extremely good sealing and repacking capability. To fit for high vacuum pressure and purity of Sputtering system, using Dry Screw Pump for Fore-line Pump to prevent oil vapor pollution, and build up a high vacuum environment by Turbo-molecular Pump. This thesis is studied to utilize the difference parameters in the substrate and target material(Target). Numerical analysis indicating that the distance between the substrate and target materials may affect the density of metal film significantly.
Peng, Kang-Tai, and 彭康泰. "Investigation of Mo5Si3/Si3N4 nanocomposites via Metal Organic Chemical Vapor Deposition and Densification Process." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/8x6zbt.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
90
The metal-organic chemical vapor deposition (MOCVD) conducted in fluidized bed has been employed for the preparation of nano-sized molybdenum silicide and silicon nitride composites. Molybdenum octooxyhydride was decomposed and molybdenum oxide was deposited onto silicon nitride partical surface in the MOCVD process. The MoOx/Si3N4 composite powder was then reduced in H2/N2 and subsequently hot-pressed to be bulk Mo5Si3 composites. XRD, SEM or TEM characterized a series of MoOx/Si3N4 composite powder in order to investigate the crystalline phase and microstructure. The results indicated that the deposition phase was amorphous MoOx and individual deposition and island like deposition were two responsible mechanisms. The Molybdenum oxide phase transformation during reducing process. Heat treatment of composite powder at 1100℃ in H2/N2 produced metallic Mo, and transformed to Mo5Si3/Si3N4 at 1300℃ within 1h. Mo5Si3/Si3N4 composite powders can be sintered by hot pressing at 1850℃ for 1h in 10 atm N2 atmosphere and density of the composites reached to 98.5﹪of theoretical density. The flexural strength, hardness, fracture toughness and microstructure of the dense Mo5Si3/Si3N4 composites were investigated and the results are discussed. Two type Mo5Si3 grain size are proposed. Specimen was tested by 4-point bending method. The strength was 912 MPa. The hardness of the composites was close to that of Si3N4. The fracture toughness increases with the increase of Mo5Si3 content.
Tsao, Teng-Yueh, and 曹騰躍. "Novel Electrostatic Deposition Method in the Layer Forming Process of Metal-powder-based Additive Manufacturing." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/b938n2.
Повний текст джерела國立清華大學
動力機械工程學系
106
Due to many basic expired patents of 3D printing technology, the product of 3D printer had entered a high-growth period. There is lots of competition in 3D printers with 3D printer technology of “fused deposition modeling” (FDM) and “stereolithography” (SLA). Although the technical threshold of metal additive manufacturing and the development funds is relatively high compared to other 3D printer technology, many countries have regarded metal additive manufacturing as an important development project due to its potential in the area of the defense industry and aerospace industry. “Electrostatic deposition method” has the characteristic of forming large-area layers in a short time. We studied the process of using the electrostatic deposition method in the metal-powder additive manufacturing technology in this research. The method we used in the research has the feature of forming the layer through the air without direct contact, making it easy to combine with subtraction processing and the potential in the area of surface repairing. The concept of combining additive and subtractive manufacturing is called hybrid manufacturing. CNC industry in Taiwan can add the function of additive manufacturing into their traditional machine tool to enhance their product value. To verify the feasibility of the method, we should study about the controllability of the layer thickness, coverage rate and the surface roughness of the layer. In the first half of the paper, we studied about the spraying method for even coverage of the dielectric film. In the second half of the paper, we modeled the electrostatic deposition process to predict the deposition thickness of the powder layer, then we verify the created model with experiment and analyze the experimental parameter. According to the results of the experiment, the applied electric field and the geometry of the experiment setup would influence the powder forming rate. We investigated the topic of applying electrostatic deposition method in the powder-based-additive-manufacturing with the feature of forming powder layer in a large area and deposition without direct contact. We did the experiments of the process and studied about the parameter and the results of deposition condition.
Huang, Wei-Sheng, and 黃惟聖. "Investigation of chromium carbide/alumina Nano-composite via Metal Organic Chemical Vapor Deposition and Densification Process." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/51385421393482413964.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
91
The metal-organic chemical vapor deposition (MOCVD) conducted in a fluidized bed has been employed for the preparation of nano-sized chromium carbide and alumina composites. Chromium hexacarbonyl(Cr(CO)6) was decomposed and successfully deposited onto alumina particles. The phase and amount of deposition depend on the deposition time and the state of fluid. The crystalline phase and microsturcture of as-deposited powders were characterized by XRD、ESCA and TEM. The result indicated the deposition was amorphous Cr2O3 exastinagas island-like (chain) type or individual type. In order to obtain Cr3C2/Al2O3 composite powder, heat treatment in graphite furnace is required. The Cr7C3/Al2O3 composite was produced from as-deposited powder by hot-pressed at 1400℃ in vacuum for 1h due to carbonization by the of carbon radicals from graphite mould. At high temperature, the conversion of chromium oxide to Cr3C2 or Cr7C3 depends on the activity of carbon. The microstructure of the dense composites was also discussed. The inclusion(Cr7C3) in Cr7C3/Al2O3 composite existed as three types. The matrix Al2O3 transformed into solid solution with a small quantity of Cr2O3. Some pores inside grain induced dislocation cell or low angle grain boundary because of large internal stress generated during cooling from the fabrication temperature 1400℃.
Chang, Chih-Wei, and 張志維. "A Study For Transparent Metal Oxide Thin Film Transistors By Low Temperature Liquid Phase Deposition Process." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/27657191621224079744.
Повний текст джерела明道大學
材料科學與工程學系碩士班
100
The goal of this study is to develop high quality and low cost metal oxide semiconductor fabrication technology. Up to now, there is less study in metal oxide semiconductor TFTs by liquid phase deposition (LPD) process. It has many advantages like low cost, good uniformity and adhesion, easy stoichiometry control, and a potential of large scale batch-type mass production. In preparation of indium titanium oxide thin film transistors, ammonium hexafluoro-titanate and boric acid were used as materials to produce titanium oxide semiconductor films with the liquid phase deposition method. In this process, indium nitrate was doped to improve the mobility. Then, aluminum electrodes were further plated on these films via a shadow mask with the thermal evaporation. The transfer characteristics of TFT device were measured by an HP-4145B semiconductor parameter analyzer. Finally, we proved that, in this preparation of TiO2 by LPD, indium nitrate is an effective doping to the TiO2. This doping made the optical energy gap down to 2.95 eV, and the average transmittance is 74.08 %, the Hall mobility as high as 7.45 cm2/Vs. The final product is a type of inverse staggered, the μsat is 0.799 cm2/Vs, threshold voltage is -5.27 V, subthreshold swing is 0.13 V/dec, and on/off current ratio is 1.39 x 106.
Chang, Yin-Yu, and 張銀佑. "Synthesis and Characterization of Metal-doped Amorphous Carbon Films Deposited by a Cathodic Arc Activated Deposition Process." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/69369145774616095311.
Повний текст джерела國立中興大學
材料工程學研究所
92
Diamond-like Carbon (DLC) films containing various metal doping were synthesized by using a cathodic-arc activated deposition (CAAD) process. Metal plasma with intensive ion energies catalyzes the decomposition of hydrocarbon gases (C2H2), and induces the formation of hydrogenated amorphous carbon films with a mixture of sp2 and sp3 carbon bonds. The composite film structure consists of a metal- doped amorphous carbon film on top of a graded metal nitride interlayer, which provides enhanced mechanical and tribological properties. In this study, the plasma characteristics of the CAAD process for the deposition of metal-doped a-C:H was investigated by Langmuir probe measurement and optical emission spectroscopy. The catalysis effect of three common transition metal plasmas, including Cr, Ti, and Zr was investigated. This experiment depicts the advantage of the catalysis effect of Cr plasma in synthesizing DLC films with a higher sp3 carbon bond ratio comparing with that of Ti and Zr plasma. The wear properties were correlated with the metal doping determined by atomic size and electronic configuration. A catalytic ability ranking of transition metals for the deposition of metal-doped amorphous carbon films was suggested. Nitrogen was also introduced to form nitrogen-containing Cr-C:H/N films, which contained a mixture of sp2 and sp3 carbon bonds. The mechanical properties were correlated with the nitrogen doping. When nitrogen atoms occupy the substitutional sites to a large percentage, a donor energy level would be created and induces an increasing electrical conductivity.
Hsin-YiSun and 孫新怡. "Assessing exposures and health risks associated with the laser metal deposition (LMD) operating process and its control strategy." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2xqq35.
Повний текст джерелаWu, Cheng-Zhang, and 吳承璋. "A Process Development Study on the Making of Dye Synthesized Solar Cells using Low Pressure Chemical Vapor Deposition Metal Doped ZnO as Electrodes." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/18354772027053627475.
Повний текст джерела龍華科技大學
化工與材料工程系碩士班
103
In this research, low pressure chemical vapor deposition (LPCVD) technique has been employed to prepare metal doped zinc oxide electrodes for dye synthesized solar cells (DSSC). The process parameters are as follow: metal Al as substrate, zinc acetylacetonate as precursor, deposition temperature at 500℃, pressure at 100-250 torrs, and metal acetylacetonates of Mg, Cu, Fe as dopants. FESEM, XRD results point out these LPCVD deposits are mostly poly crystal ZnO with (002) orientation. IV measurements of as assembled DSSC show that cell efficiency around 6-8%, implying these LPCVD doped ZnO can work successfully as the electrodes for solar cells. It is interesting that most LPCVD ZnO deposits on aluminum surface are composed mainly by thin wires (line diameters less than 500 nm) of ZnO crystals. This might be attributed to the eutectic driven vapor liquid solid growth phenomena; as according to the phase diagram of Zn/Al, the melting point for Zn/Al alloy eutectic is 420℃. Therefore, LPCVD ZnO on Al surface might create numerous Zn/Al eutectic tiny droplets densely distributed on the depositing surface. These eutectic droplets work as the ZnO line growing points because of their capability to absorb materials quickly. On the other hand, XRD/IV cross analysis indicate that DSSC will have a better performance, if the Al2O3 diffraction peaks are weak in XRD patterns. It was suggested that the adsorbed dopant molecules such as Mg(acac)2 might inject electrons to aluminum surface, thereby preventing oxidation of Al, and appearance of Al2O3. This leaves substrate has more regimes made by aluminum, rather than high resistivity alumina. Such further improve the efficiency of LPCVD ZnO DSSC. Based on collected data, which confirm the optimum condition to make DSSC is that perform LPCVD at low oxygen concentration, doped Zn(acac)2 with minor amount (< 3 wt %) of Mg(acac)2 or Fe(acac)3, the as assembled DSSC could have a current density of 0.825 mA/cm2, and efficiency of 10.31%.
Yaddanapudi, G. R. Krishna. "Effect of Process Parameters on the Growth of N-Polar GaN on Sapphire by MOCVD." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2662.
Повний текст джерелаLin, Chi-Ying, and 林奇瑩. "To Recover Heavy Metals from MSWI Fly Ash Liquid after Acid Washing by Electro-deposition Process." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/13816358035050142931.
Повний текст джерела國立中興大學
環境工程學系所
97
In recent years, because the industry and commerce is fast growing, there''re almost 6 million tons of domestic wastes produced every year. It''s unable to dispose of the domestic wastes effectively by traditional landfill, so the government finished the construction of 24 large-scale incinerators in February 2008. According to EPA statistic in Taiwan, it''s nearly 90% of domestic wastes was treated by Municipal Solid Waste Incinerators (MSWI), but it will produce bottom-ash and fly-ash. The producing amount is 0.044 ton Fly ash/ ton Solid waste. And the MSWI fly ash TCLP (Toxicity Characteristic Leaching Procedure) test results showed that the average concentration of heavy metal lead was about 50 mg/L, which is ten times over the regulation limit 5.0 mg/L, and TCLP disqualification rate is up to 52.9%. If fly ash don’t take treatment through appropriate stability / solidification, it may cause the environmental pollution of heavy metal. The fly ash usually has characteristic of high pH, so that much heavy metal is deposited on the fly ash in the form of hydroxide. This research will dissolve Pb and Cu from fly ash by acid washing, and then utilize electrodeposition technology to deal the acid-washing liquid. The purpose is wanted to discuss the ability of dissolving heavy metal by acid-washing procedure, and the efficiency of electrodeposition technology to recover the heavy metal from acid-washing liquid. The results of study reveal that acid-washing the fly ash by L/S=20/1 with 0.5N HNO3 could cut down the weight by 68.6% after acid-washing. The dissolution rates of Pb and Cu are 55.6% and 83.2% respectively, and then the residue rates of Pb rises from 34% to 66%. By means of electrodeposition experiment, the removing rates of Pb at electric current 5A, 10A, 15A are 54%, 74%, 84% respectively; Cu is differentiated 90%, 80%, 82%. As for rate of recovery, it''s the best to fix electric current at 10A which can recover 25.7% of the Pb and 59.8% of Cu. The results reveal that it can be looked forward to recover heavy metal from MSWI fly ash by the combined procedure with acid-washing and electrodeposition.