Дисертації з теми "Carbothermal reduction and nitridation"
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Cho, Young Whan. "Synthesis of nitrogen ceramic powders by carbothermal reduction and nitridation." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277802.
Повний текст джерелаTerner, Mark Robert. "The production of low-cost α-sialons via carbothermal reduction-nitridation of slag-based mixtures". Monash University, School of Physics and Materials Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9577.
Повний текст джерелаHarrison, Robert. "Processing and characterisation of ZrCxNy ceramics as a function of stoichiometry via carbothermic reduction-nitridation." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/24810.
Повний текст джерелаDu, Xiaoyang 1960. "Carbothermal reduction of ilmenite and fayalite." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290600.
Повний текст джерелаDewan, Mohammad Ashikur Rahman Materials Science & Engineering Faculty of Science UNSW. "Carbothermal synthesis of titanium oxycarbide." Awarded By:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/44511.
Повний текст джерелаDurham, Simon J. P. "Carbothermal reduction of silica to silicon nitride powder." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74221.
Повний текст джерелаSol-gel processing was found to provide superior mixing conditions over dry mixing, which allowed for complete conversion to silicon nitride at optimum carbon:silica ratios of 7:1. The ideal reaction temperature was found to be in the range of 1500$ sp circ$C to 1550$ sp circ$C. Suppression of silicon oxynitride and silicon carbide was achieved by ensuring that: (a) the nitrogen gas was gettered of oxygen, and (b) that the gas passed through the reactants. Thermodynamic modelling of the Si-O-N-C system showed that ordinarily the equilibrium conditions for the formation of silicon nitride are very delicate. Slight deviations away from equilibrium leads to the formation of non-equilibrium species such as silicon carbide caused by the build-up of carbon monoxide. Reaction conditions such as allowing nitrogen gas to pass through the reactants beneficially moves the reaction equilibrium well away from the silicon carbide and silicon oxynitride stability regions.
The particle size of silicon nitride produced from carbon and silica precursors was of the order of 2-3 $ mu$m and could only be reduced to sub-micron range by seeding with ultra-fine silicon nitride. It was shown that the mechanism of nucleation and growth of unseeded reactants was first nucleation on the carbon by the reaction between carbon, SiO gas and nitrogen (gas-solid reaction), and then growth of the particles by the gas phase reaction (CO, SiO, N$ sb2$).
Bejarano, Cesar. "Carbothermal reduction of sulfur dioxide using oil-sands fluid coke." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ53340.pdf.
Повний текст джерелаJain, Anubhav. "Synthesis and Processing of Nanocrystalline Zirconium Carbide Formed by Carbothermal Reduction." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4797.
Повний текст джерелаTaneka, S. "Carbothermal reduction of friable chromite in a small-scale transferred-arc furnace." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37873.
Повний текст джерелаKononov, Ring Materials Science & Engineering Faculty of Science UNSW. "Carbothermal solid state reduction of manganese oxide and ores in different gas atmospheres." Publisher:University of New South Wales. Materials Science & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41459.
Повний текст джерелаMariappan, L. "In-Situ Synthesis Of A12O3_ZrO2_SiCw Ceramic Matrix Composites By Carbothermal Reduction Of Natural Silicates." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/215.
Повний текст джерелаDuddukuri, Ramesh. "SYNTHESIZING AND CHARACTERIZATION OF TITANIUM DIBORIDE FOR COMPOSITE BIPOLAR PLATES IN PEM FUEL CELL." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/862.
Повний текст джерелаCheng, Zhe. "Reaction Kinetics and Structural Evolution for the Formation of Nanocrystalline Silicon Carbide via Carbothermal Reduction." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5896.
Повний текст джерелаSondhi, Anchal. "Investigations in the Mechanism of Carbothermal Reduction of Yttria Stabilized Zirconia for Ultra-high Temperature Ceramics Application and Its Influence on Yttria Contained in It." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc500159/.
Повний текст джерелаFiefhaus, Silas R. "The Optimization of The Synthesis and Characterization of Vapor-Liquid-Solid Grown ZnO Nanowires." UKnowledge, 2016. http://uknowledge.uky.edu/chemistry_etds/62.
Повний текст джерелаAdipuri, Andrew Materials Science & Engineering Faculty of Science UNSW. "Chlorination of Titanium Oxycarbide and Oxycarbonitride." Publisher:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/44405.
Повний текст джерелаFontaine, Florian. "Composites à matrice carbone-oxyde et carbone-nitrure : thermodynamique de l'élaboration et son impact sur les propriétés physico-chimiques, thermiques et mécaniques des composites." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14217/document.
Повний текст джерелаCarbon/carbon composites exhibit excellent mechanical and thermal properties at high temperature that make them espe-cially suitable for ablation or friction pieces. Their sensitivity toward oxidation above 400°C has lead to the will of doping them with refractory ceramics that are nonoxidizable or with a high oxidation temperature. The sol-gel process allowed to introduce 1 % in volume of titanium or aluminum oxide or nitride in the matrix. Nitrides are obtained by carbothermal nitridation of the oxide films. Two types of sols were used: the “standard” ones and those with extra sucrose. Sucrose is added to prevent pyrocarbon consumption during the nitridation. Furthermore, it was shown that it has an impact on the nitridation rate. Charged composites are then densified by Chemical Vapor Infiltration, which induces phases transforma-tions that were predicted by thermodynamics: titanium nitride films are partially carburized (formation of titanium carbonitride) and titanium dioxide films are reduced (formation of titanium oxycarbide). Aluminum-based films are more stable and don’t undergo any transformation. Thermal diffusivity of the as-synthesized composites is not much modified by the addition of these ceramics while the tensile and compressive strength are slightly increased. By the way, composites are hardened. Their oxidation kinetics is slowed down. Aluminum-rich composites exhibit a weight loss divided by two compared to the C/C reference. All those properties are directly, or not, linked to the composition of the sols, in particular to their sucrose content. Indeed, it was shown that sucrose-containing sols rather jellify on the surface of the composite, thus preventing the diffusion of precursor gases to the heart of the pieces. The final porosity is then modified. The porosity has an important impact on the compressive strength, thermal diffusivity and oxidation kinetics of the synthesized composites
Carvalho, Raquel Guilherme de. "Redu??o carbot?rmica de TiO2 por descarga em c?todo oco." Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15673.
Повний текст джерелаConselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
In this study we used the plasma as a source of energy in the process of carbothermic reduction of rutile ore (TiO2). The rutile and graphite powders were milled for 15 h and placed in a hollow cathode discharge produced by in order to obtain titanium carbonitride directly from the reaction, was verified the influence of processing parameters of plasma temperature and time in the synthesis of TiCN. The reaction was carried out at 600, 700 and 800˚C for 3 to 4 hours in an atmosphere of nitrogen and argon. During all reactions was monitored by plasma technique of optical emission spectroscopy (EEO) to check the active species present in the process of carbothermal reduction of TiO2. The powder obtained after the reactions were characterized by the techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The technique of EEO were detected in all reactions the spectra CO and NO, and these gas-phase resulting from the reduction of TiO2. The results of X-ray diffraction confirmed the reduction, where for all conditions studied there was evidence of early reduction of TiO2 through the emergence of intermediate oxides. In the samples reduced at 600 and 700˚C, there was only the phase Ti6O11, those reduced to 800˚C appeared Ti5O9 phases, and Ti6O11 Ti7O13, confirming that the carbothermal reduction in plasma, a reduction of the ore rutile (TiO2) in a series of intermediate titanium oxide (TinO2n-1) where n varies between 5 and 10
Neste trabalho foi utilizado o plasma como fonte energ?tica no processo de redu??o carbot?rmica do min?rio rutilo (TiO2). Os p?s de rutilo e grafite foram mo?dos durante 15 h e introduzidos numa descarga produzida por c?todo oco a fim de obter carbonitreto de tit?nio diretamente da rea??o, sendo verificado a influ?ncia dos par?metros de processamento de plasma, temperatura e tempo na s?ntese de TiCN. As rea??o foram efetuadas a 600, 700 e 800˚C por 3 e 4 horas numa atmosfera de nitrog?nio e arg?nio. Durante todas as rea??es o plasma foi monitorado pela t?cnica de espectroscopia de emiss?o ?ptica (EEO) para verificar as esp?cies ativas presente no processo de redu??o carbot?rmica de TiO2. Os p?s obtidos ap?s as rea??es foram caracterizados pelas t?cnicas de difra??o de raios X (DRX) e microscopia eletr?nica de varredura (MEV). Pela t?cnica de EEO foram detectados em todas as rea??es os espectros CO e NO, sendo essas fases gasosas resultante da redu??o do TiO2. Os resultados de difra??o de raios X confirmou essa redu??o, onde para todas as condi??es estudadas houve evid?ncia de in?cio da redu??o do TiO2 atrav?s do aparecimento de ?xidos intermedi?rios. Nas amostras reduzidas a 600 e 700˚C observou-se apenas a fase Ti6O11, naquelas reduzidas a 800 ˚C apareceram as fases Ti5O9, Ti6O11 e Ti7O13, comprovando que com a redu??o carbot?rmica em plasma, houve redu??o do min?rio rutilo (TiO2) em uma s?rie de ?xido intermedi?rios de tit?nio (TinO2n-1) onde n varia entre 5 e 10
Chuayboon, Srirat. "Solar fuels production from thermochemical gasification and reforming of carbonaceous feedstocks." Thesis, Perpignan, 2019. http://www.theses.fr/2019PERP0019.
Повний текст джерелаThe investigated solar thermochemical processes consist of the thermochemical conversion of solid and gaseous carbonaceous feedstocks into syngas as well as metal oxides reduction into metal commodities utilizing concentrated solar energy to drive endothermic chemical reactions, thereby enabling intermittent solar energy storage into solar fuels and avoiding CO2 emissions. This work aims to experimentally investigate three key solar thermochemical conversion approaches regarding biomass gasification, chemical looping reforming of methane, and carbothermal reduction of ZnO and MgO. Solar gasification and solar chemical looping reforming allowed valorizing wood biomass and methane into syngas, while solar carbothermal reduction was applied to produce Zn and Mg from ZnO and MgO. Such solar thermochemical processes were performed in 1.5 kWth prototype solar chemical reactors, utilizing highly concentrated sunlight provided by a solar concentrator at PROMES laboratory, Odeillo, France. The impact of controlling parameters of each process on the reaction mechanism, conversion, yields, and process performance, during on-sun testing was investigated and evaluated thoroughly. Such processes were proved to significantly improve the chemical conversion, syngas yields, energy efficiency, with solar energy storage into transportable fuels, thereby outperforming the conventional processes. Moreover, their feasibility, reliability, and robustness in converting both methane and biomass feedstocks to syngas as well as producing Mg and Zn metals in batch and continuous operation under vacuum and atmospheric conditions during on-sun operation were successfully demonstrated
Réjasse, Florian. "Etude de la réactivité des dioxydes métalliques du groupe IVb en présence de carbone par une approche (micro)-structurale : Application à la modélisation des diagrammes de phases ternaires Me-C-O (où Me = Ti, Zr, Hf)." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0099/document.
Повний текст джерелаDuring this work, the reactivity of group IVb dioxides (TiO2, ZrO2, HfO2) in contact with turbostractic carbon has been investigated in order to understand the reactional mechanisms of the carbothermal reduction. This way of synthesis has also allowed us to obtain oxycarbides phases in powder form to study the different stability domains of solids solutions with respect to the temperature of heat treatment. The addition of oxygen within the crystalline structure modifies the sintering behaviour of these materials and also their macroscopic properties. Consequently, the determination of solid solution boundaries requires an accurate methodology. A broad panoply of characterization techniques are coupled (Elemental analysis, XRD, Quantification of phases, TEM) to determine the compositions of oxycarbide phases. In order to complete this study, the reactivity of titanium carbide monoliths in contact with titanium dioxide has been studied during heat treatments of annealing under pressure in confined atmosphere. The identification of phases in equilibrium constitutes diagrammatic data which are necessary for the preliminary attempts of thermodynamic modeling of ternary phases diagrams Me-C-O (where Me = Ti, Zr, Hf) using the semi-empirical CALPHAD method
Borchardt, Lars, Claudia Hoffmann, Martin Oschatz, Lars Mammitzsch, Uwe Petasch, Mathias Herrmann, and Stefan Kaskel. "Preparation and application of cellular and nanoporous carbides." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138910.
Повний текст джерелаDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
Borchardt, Lars, Claudia Hoffmann, Martin Oschatz, Lars Mammitzsch, Uwe Petasch, Mathias Herrmann, and Stefan Kaskel. "Preparation and application of cellular and nanoporous carbides." Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27792.
Повний текст джерелаDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
Zeng, Wen Hong, and 曾文宏. "Synthesize aluminium nitride from carbothermal reduction & nitridation of aluminium hydroxide." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/47783247357525260525.
Повний текст джерелаHsu, Pei-Ju, and 徐沛儒. "The carbothermal reduction and nitridation of rice husk ash with iron powder addition." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/35154394454770268886.
Повний текст джерела國立中央大學
化學工程與材料工程研究所
90
The carbothermal reduction and nitridation of rice husk ash with iron powder addition was investigated by weight change measurement. In this study, the operating variables have been discussed include: nitrogen flow rate, amount of iron powder addition in the reactant, pellet-forming pressure, sample weight, and reaction temperature. The analysis of this experiment is conducted by inductively coupled plasma-mass spectrometer (ICP-MS), element analysis (EA), BET surface area, X-ray diffraction (XRD) and scanning electron microscope (SEM). The experimental results indicated that the conversion of rice husk ash is increased with an increasing nitrogen flow rate and the effect is not appreciable when the flow rate exceeds 500ml/min. The conversion of rice husk ash is increased with an increasing amount of iron powder addition in the reactant. Increasing the pellet-forming pressure could increase the conversion, the effect is not appreciable when the pellet-forming pressure is above 9.65x105 kPa. Moreover, the reaction rate and the conversion of the rice husk ash are significantly increased with higher reaction temperature. The reaction product is fibrous shape β- SiC with iron addition. We conjectured that the formation of liquid Fe-Si alloy is an important way for β- SiC growth. In the chemical reaction controlled region, the activation energy of the reaction is 566.69 kJ /mol when iron powder addition is 1wt% .
Wang, Yung-Mou, and 王勇謀. "The Carbothermal Reduction and Nitridation of Rice Husk Ash with Silicon Powder Addition." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/36570756694452070335.
Повний текст джерела國立中央大學
化學工程與材料工程研究所
91
Abstract The carbothermal reduction and nitridation of rice husk ash with silicon powder addition was investigated by weight change measurement. The reaction were carried out in a vertical reaction tube heated by a tubular furnace. In this study, the operating variables have been discussed included: nitrogen flow rate, amount of silicon powder addition in the reactant, grain size, sample weight and reaction temperature. The analysis of this experiment is conducted by element analysis (EA), inductively coupled plasma-mass spectrometer (ICP-MS), BET surface area, X-ray diffraction (XRD) and scanning electron microscope (SEM). The experimental results indicated that the conversion of rice husk ash is increased with an increasing nitrogen flow rate and the effect is not appreciable when the flow rate exceeds 400ml/min. The conversion of rice husk ash is increased with an increasing amount of silicon powder addition in the reactant. Reducing the grain size of rice husk would accelerate the reaction rate. Moreover, the reaction rate and the conversion of rice husk ash is significantly increased with higher reaction temperature. The reaction product is fibrous shape a-Si3N4 with silicon addition. In the chemical reaction controlled region, the activation energy of the reaction is 478.5 kJ/mol when silicon powder addition is 1wt %.
Yu, Cheng-Kuo, and 余建國. "A Study on the Kinetics of Carbothermal Reduction & Nitridation of Titanium Dioxide." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/00891119641732068943.
Повний текст джерела國立臺灣科技大學
化學工程研究所
83
Carbothermal reduction and nitridation of titanium dioxide was investigated by X-rey diffraction and gas chromatograph. The effect of the following factors on the formation rate of TiNxCY has been studied:(1)flow rate of nitrogen(2)sample height(3)rea ction temperature(4)C/TiO2 molar ratio(5)grain size(6)initial bulk density of solid sample(7)carbon source and(8)TiO2 source. Experimental results indicated that anatase was transformated to rutile before it was reacted to produce TiN. The solid product of the reaction is the solid solution of TiN and TiC. The amount of TiN in the solution product may be increased by increasing the reaction temperature or decreasing the initial molar ratio of C/TiO2 . The gas products of the reaction are mostly CO and trace amount of CO2. The reaction rate was found to be increased by increasing the nitrogen flow rate , molar ratio of C/TiO2 or reaction temperature. The rate was also observed to be increased by decreasing the sample height , the grain size of carbon or titanium dioxide or initial bulk density Experimental results showed that a chemical reaction control region can be reached if the flow rate of nitrogen is higher than 1.5E-5 m3/s and the sample height is kept under 0.004 m . Empirical rate expressions of the yoeld of TiNxCy were also determined shown.
Chen, Yan-Wei, and 陳彥瑋. "Process Development for Carbothermal Reduction and Nitridation Synthesis of alpha-SiAlON Phosphors by Using Solution Combustion Synthesized Precursors." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/71315113766484607359.
Повний текст джерела國立成功大學
化學工程學系碩博士班
97
A commercial and potential method to synthesis nitrides or oxynitrides currently is reducing oxides at nitrogen atmosphere. Our laboratory has already successfully product silicon nitride and aluminum nitride from silicon oxide and aluminum oxide. This study used previous technical basis that our laboratory established to synthesis an advanced oxynitride material, SiAlONs which include silicon, aluminum, oxygen and nitrogen atom in its structure. Solution combustion synthesis we used that could help nitridation reaction precursors mix very well and close to nano-scale particle size. We could obtain α-SiAlON which was mainly phase in the product after precursors underwent carbothermal reduction nitridation and doped activator made the host have luminescent property. The study mainly focused on 1. carbon ratio, 2. reaction temperature, 3. seeds effects, 4. activator concentrations, 5. the effects of morphology of the precursors. The analytic instruments included XRD, PL, SEM and the best result achieved in this study when carbon was 4 times theoretical value, reaction temperature was 1500℃, Eu2+ was doped 0.5 and seed was doped 50 mol﹪.According to the SEM, we observed particle size distribution was from submicron to micron.
Chen, Jia-hong, and 陳嘉鴻. "Carbothermal reduction sintering of silicon carbide." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/89974486629123552901.
Повний текст джерела國立聯合大學
材料科學工程學系碩士班
96
The objective of this study is to investigate the structure and electrical resistivity of SiC ceramics that added different amount of boron carbides, sintered at air and CO/CO2 in 1350 ~ 1400℃. This research shows that optimal mixed ratio of partical size of 1 ~ 10 μm and 40 ~ 60 μm by slip-casting in plaster of Paris and comparison of properties of bulk density, microstructure and electrical resistivity of sintered body was produced by adding amount of 0%、1%、2%、5% of boron carbide and sintering at various temperature in difference atmospheres. According to experiment result, we obtained the optimal condition without plasticizer that particle size of 1 ~ 10μm, 40 ~ 60μm and water of mixed ratio 3:3:4. We obtained the result that the highest density of sintered SiC by adding 1% boron carbide using Archimedes’ principle. Comparison of the result that the bulk density of sintering in air higher than sintering at CO/CO2 atmosphere due to formation of silica by SiC of oxidation infiltrated between particles. According the analysis result by XRD, generation of β-SiC by sintering at CO/CO2 atmosphere leads to electrical resistivity of sintering body decrease. In addition, we obtained that relative content of β–SiC significantly increased with higher reaction temperature by analysis of XRD and NMR.
LEE, JYH-JEN, and 李志仁. "Kinetics of Carbothermal Reduction of Zinc Ferrite." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/41745166098073330366.
Повний текст джерела國立臺灣科技大學
化學工程系
88
Kinetics of carbothermal reduction of zinc ferrite was studied in this study. A box furnace was used to synthesize zinc ferrite. X-ray diffractometer, wetting-chemical analysis method, surface area meter and scanning electron microscope were employed to monitor the changes of composition and physical properties during reaction. On the other hand, thermogravimetic analyzer was used to study the effects of processing parameters on the conversion rate of zinc ferrite. It was found that zinc ferrite of 96.84% pure could be synthesized under following conditions : molar ratio of ZnO/Fe2O3 of 1 ; air flown over sample through suction of hood ; temperature of 1,123 K and time of 18,000 s. Zinc ferrite was found to decompose to ZnO and Fe2O3 initially. ZnO was then rapidly reduced to zinc vapor and carbon monoxide which were escaped from solid sample. Fe2O3 was also reduced FeO. However, the rate was slower. It was transformed to Fe through FeO. Pore surface area of solid sample increased with reaction time while pore volume and pore diameter were increased and then decreased with time. They are due to the escaping of zinc vapor and the expansion of FeO. A model was proposed to explain the reaction. As to the effects of processing parameters on the rate of carbothermal reduction of zinc ferrite, following results were found : conversion rate of zinc ferrite could be increased by increasing the flow rate of agron stream or reaction temperature. The rate was also found to be increased by decreasing the height of solid sample, molar ratio of ZnFe2O4/C, the grain size of carbon agglomerate or the initial bulk density of solid sample.
Yang, Yi-lin, and 楊憶琳. "Preparation of Bio-Carbide by Carbothermal Reduction." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/10511679917928245206.
Повний текст джерела國立聯合大學
化學工程學系碩士班
94
The research of the ceramic material mineralized from the biomaterial has become a popular trend and has been widely used in many applications. This work intends to combine bionics and materials science by carbothermal reduction to prepare bio-carbides. The discarded timber was selected as the raw material due to the rise in environmental consciousness and the consideration of the cost of R&D. The timber was carbonized at high temperature for 2 hours in the inert gas. The carbonized wood was then selected as the porous template. Porous bio-carbides with woodlike microstructures were prepared by carbothermal reduction reaction at high temperature. This kind of woodlike microstructures was fabricated either by infiltrating one of the following species, TEOS/TTIP/Si/Ti, into woodceramics under vacuum condition or in the inert gas. This research focuses on the preparations of porous bio-template, bio-SiC, bio-TiC, and porous bio-Ti3SiC2. The results provide some useful guidelines in biomimetic processes.
Lin, Thung-Hsien, and 林宗憲. "Synthesis of Electronic Grade Silicon Carbide Powders by Carbothermal Reduction." Thesis, 2015. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22103TIT05397033%22.&searchmode=basic.
Повний текст джерела國立臺北科技大學
資源工程研究所
103
Recently, SiC has been widely used in many fields owing to its high hardness, heat resistance, corrosion resistance, oxidation resistance and high thermal conductivity. In this study, high purity SiO2 powders (> 99.99%) were used as the source of silicon and the graphite powders were employed as the reducing agent. The objective of this study is to synthesize high purity SiC powders (> 99.99%) by carbonthermal reduction under argon atmosphere. Due to the high crystallinity of graphite, the chemical bond can&;#39;t be broken easily without adding catalyst, optimizing reaction temperature and time have been conducted. All experiments were operated at 1400 ~ 1600℃ for certain hours. The purified products were characterized by XRD and SEM. The purity of SiC was acquired through ICP-AES. The results indicated that β-SiC with the purity of 99.99895% was synthesized. A series of experimients with parameters including various molar ratio of graphite to silica, reaction temperature, reaction time and after-treatment were carried out to investigate the optimal condition for the synthesis of SiC.
Meng-PangChang and 張孟邦. "Growth of ZnGa2O4 nanowires on a ZnO film by carbothermal reduction." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/85253309652029437334.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
98
The growth of ZnGa2O4 nanowires (NWs) on ZnO-coated Si substrates by carbothermal reduction of Ga2O3 powder as a function of the thickness of ZnO film and the weight of Ga2O3 powder was studied. With the weight of Ga2O3 powder held at 0.3-0.4 g, abundant and pure ZnGa2O4 NWs could grow at 550-650℃ on the 0.9 μm-thick ZnO film. Thinner ZnO film, more Ga2O3 powder, and higher substrate temperature favored the growth of Ga2O3 nanobelts. The growth of ZnGa2O4 NWs followed the vapor-solid process. The photolumescence spectra of ZnGa2O4 NWs showed the emission peaks around 460-480 nm.
Chuang, Chih-Ming, та 莊誌銘. "The effects of transition metals on carbothermal reduction synthesis ofβ-SiC". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/59958600947990128356.
Повний текст джерела大同大學
材料工程學系(所)
92
This research is divided into two parts. In the first part, I will use phenolic-resin and Ludox were as the starting materials and add transition metals and use carbothermal reduction to synthsize β-SiC powder. I will discuss the effect of the kinds and the amount of additive on reaction temperature of β-SiC and powder properties. The other part of this research is that I will use activated carbon fabric and TEOS to prepare SiC fabric by shape memory synthesis. I hope that the morphology of SiC preserved the morphology of carbon. Adding Fe, Co, Ni, Cu enhance β-SiC formation at lower temperature. Adding Fe and Cu caused product to sinter. The product remained as powder when reactants contained Co and Ni. Although reactant with Cu can form β-SiC at 1300℃, the melting point of Cu is lower than reaction temperature, which leads reactants stick together as a cake the reaction surface decreases. Consequently, the reactant can not effectively convert into β-SiC. Adding Mn into reactants can not produce β-SiC at lower temperature. The reason is similar to that of adding Cu. The existence of Mn promoted SiO(g) formation but can not enhance reactants to convert to β-SiC. The yields of adding 1wt% Fe, Co, Ni after reaction at 1400℃ are higher than that of reactants without additives after reaction at 1400℃. The yields of adding 1wt% Fe, Co are even higher than reactants without additives after reaction at 1500℃. It can be seen that adding 1wt% Fe, Co, Ni can promote β-SiC formation at low temperature. The highest yield is by adding 1wt% Fe which is 76.87%. Adding Co has the second highest yield (73.14%) and adding Ni has 30.40% of yield, but it near to reactants without additives after reaction at 1500℃ (32.07%). The product of adding 1wt% Fe was sintered so that it needed to crush and mill. The yield of samples adding 1wt% Co was near to that of sample adding 1wt% Fe. The powder contained few whisker. Its particle size is about 100~200nm. The product of samples adding 1wt% Ni contains a lot of whisker. After reaction at 1500℃ for 8hr, activated carbon fabric can convert to β-SiC fabric. The product remains the shape of carbon and is flexible. Activated carbon fabric has many micro-pore on surface after activated process. The micro-pore provides many reaction area and promote reaction.
Chen, Chih-yung, and 陳智勇. "Kinetics of Synthesis of Silicon Carbide through Carbothermal Reduction of Silicon Oxide." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/94220456840643778964.
Повний текст джерела國立台灣工業技術學院
化學工程技術研究所
85
The kinetics of synthesis of silicon carbide through carbothermal reduction of silicon dioxide has been studied in our experiment. X-ray diffraction analysis were employed to determine the content of products. The effects of several parameters on the reaction rate were obtained. Experimental results indicated that the reaction rate could be increased by decreasing the flow rate of He, the SiO2/C ratio, the grain size of silicon oxide or carbon and the initial density of solid sample. The rate could also be increased by increasing the height of solid sample and the reaction temperature. It was also found implicitly that SiO was an intermediate product. The activation energy of the production of β-SiC was found to be 436kJ/mole. Following are the empirical rate expressions of conversions of carbon, silicon oxide and production of silicon carbide obtained by regression of the experimental data: dCc-rc = - -------- = 7.6E4 *exp(-412,132/RT) *dsio2^(-0.742)* dc^(-0.549) dt *Csio2^(0.308)* Cc^(0.316)*Csic^(-0.046)*D^(-0.218) *f^(-0.311)*h^(0.460) dCc-rsio2 = - ------ = 1.2E4 *exp(-401,513/RT) *dsio2^(-0.801)*dc^(-0.392) dt *Csio2^(0.476)*Cc^(0.283)*Csic^(-0.077)*D^(-0.241) *f^(-0.304)*h^(0.412) dCsicrsic = -------- = 2.5E4 *exp(-436,012/RT) *dsio2^(-0.474)*dc^(-0.315) dt *Csio2^(0.407)*Cc^(0.328)*Csic^(0.013)*D^(-0.234) *f^(-0.352)*h^(0.414) The applicable range of the empirical rate expressions are flow rate of He 1x10-5 - 5x10-5 m3/s, sample height 0.007 - 0.020m, reaction temperature 1,573 - 1,773K, SiO2/C molar ratio 1/5 - 1/1, grain size of silicon oxide 0.000042 - 0.000113m, grain size of carbon 0.000051 - 0.000134m and initial bulk density 339.5 - 577.2kg/m3.
Liao, Kuo-Hong, and 廖國宏. "The Influence of silicon on the Carbothermal Reduction and Nitriding of Silica." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/03150444976075271505.
Повний текст джерела國立中央大學
化學工程研究所
88
The carbothermal reduction and nitridation of silicon dioxide with silicon powder addition was investigated by weight gain measurement. The reaction were carried out in a vertical reaction tube heated by a tubular furnace. In this study, the operating variables have been discussed included: nitrogen flow rate, amount of silicon powder added in the reactant, silicon dioxide/carbon molar ratio, sample weight, and reaction temperature. The analysis of this experiment is conducted by X-ray diffraction (XRD), scanning electron microscope (SEM), BET surface area, and inductively coupled plasma-mass spectrometer (ICP-MS). The experimental results indicated that the conversion of silicon dioxide is increased with an increasing nitrogen flow rate and the effect is not appreciable when the flow rate exceeds 500ml/min. The conversion of silicon dioxide is increased with an increasing amount of silicon powder added in the reactant. An excess of carbon powder and decrease of the sample weight are required to promote the conversion, however, the effect is not appreciable when the molar ratio is above 5 and sample weight is below 0.3g. Moreover, the reaction rate and the conversion of silicon dioxide is significantly increased with higher reaction temperature. The reaction product is fibrous shape β-SiC with silicon powder addition. We conjectured that the large formation of gaseous SiO is an important way for β-SiC growth.
Yi-ChiHuang and 黃奕齊. "Microstructure and Mechanical Properties of SPS Sintered Nano-Si3N4 Ceramics via Carbothermal Reduction Method." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/67670024427847766667.
Повний текст джерелаLin, Yu-Chiao, and 林郁喬. "The study of the growth of SiO2 nanowires via carbothermal reduction of CuO powders." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/53098791869146267199.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
93
The growth of SiO2 nanowires(SiONWs)via carbothermal reduction of CuO powders as functions of the growth temperature, time, Ar flow rate, the carbon concentration in the CuO/carbon powders, and the oxygen concentration in the Ar/O2 flow were studied. Significant amount of SiONWs were grown on the Si substrate without the catalyst from the CuO/carbon powders at a temperature of 1000℃-1100℃ in a flowing Ar with the flow rate of 100 sccm. Without using CuO/carbon powders SiONWs could not be readily grown. A small amount of SiC associated with SiONWs was grown from the CuO/carbon powders with a higher proportion of carbon. The minimum Ar flow rate required for the growth of SiONWs was about 10 sccm and the amount as well as the diameter of SiONWs increased with increment of the Ar flow rate, revealing that the vapor transport assisted by the Ar flow is an important mechanism for the nucleation and growth of SiONWs. The growth of SiONWs mainly originated in the cracks which were formed in the Si substrate due to the generation of SiO(g) from the reaction between CO2 and the Si substrate. The introduction of O2 into the Ar flow could generate siginficant amount of CO and thereby suppress the growth of SiONWs. The present studies reveal that the growth of SiONWs via carbothermal reduction of CuO powders mainly follows the vapor-solid(VS)mechanism.
Hsieh, Wen-yuan, and 謝文元. "Growth of WO3 nanowires and Ge-Si1-xGexOy core-shell nanowires via carbothermal reduction." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/56987325131401913860.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
95
Effects of adding GeO2 to WO3 powders on enhancing the growth of WO3 nanowires (NWs) and Ge-Si1-xGexOy core-shell NWs ( Ge-SiGeO NWs) via the carbothermal reduction process in Ar at a flow rate of 25-400 sccm at a temperature of 900-1100°C were studied. Upon the thermal evaporation or carbothermal reduction of WO3 powders at 900°C no NWs were grown. The growth of WO3 NWs follows the vapor-solid (VS) process, where GeO2 powders act as an oxidizer. Introducing 1-5% O2 into flowing Ar enhanced the growth of GeO2 NWs and WO3-GeO2 core-shell NWs at 900°C. More O2 suppressed the growth of NWs because of the exhaustion of much graphite powders. At 1050-1100°C the growth of Ge-SiGeO NWs following the VS process were observed. In addition, the growth mechanisms of WO3, GeO2, and Ge-SiGeO NWs are discussed, respectively.
Heidlage, Michael Gregory. "Sustainable ammonia synthesis via thermochemical reaction cycle." Diss., 2018. http://hdl.handle.net/2097/38948.
Повний текст джерелаDepartment of Chemical Engineering
Peter H. Pfromm
Since its inception, the Haber-Bosch (HB) process for ammonia (NH3) synthesis has allowed for a significant increase in global food production as well as a simultaneous decrease in global hunger and malnutrition. The HB process is estimated to be responsible for the subsistence of 40% of the world population as approximately 85% of the over 182 metric tons of NH3 produced in 2017 was used as fertilizer for crop production. The natural gas consumed (mostly to generate H2) represents approximately 2% of the global energy budget, while the CO2 produced is about 2.5% of all global fossil CO2 emissions. Approximately 40% of food consumed is essentially natural gas transformed by the HB process into agricultural products. However global food production will need to double due to expected increase in world population to 9.6 billion by 2050 and rising demand for protein among developing nations. A novel thermochemical reaction cycle for sustainable NH3 synthesis at atmospheric pressure is explored herein. Both thermochemical and kinetic rationales are discussed regarding choice of Mn as the cycled reactant. The energetic driving force for these reactions is conceptually derived from concentrated solar energy. Mn was reacted with N2 forming Mn-nitride, corrosion of Mn-nitride with steam at 500 °C formed MnO and NH3, and lastly MnO was reduced at 1150 °C in a 4 vol % CH4 – 96 vol % N2 stream to Mn-nitride closing the cycle. Optimum nitridation at 800 °C and 120 min produced a Mn6N2.58-rich Mn-nitride mixture containing 8.7 ± 0.9 wt. % nitrogen. NH3 yield was limited to 0.04 after 120 min during nitride corrosion but addition of a NaOH promotor improved NH3 yield to 0.54. Mn6N2.58 yield was 0.381 ± 0.083 after MnO reduction for 30 min with CO and H2 but no CO2 detected in the product. Mn-nitridation kinetics were investigated at temperatures between 600 and 900 °C for 10 and 44 μm reactant powder particle sizes. That equilibrium conversion decreased with increasing temperature was confirmed. Jander’s rate law, which assumes gaseous reactant diffusion through a solid product layer, described the experimental data reasonably well. The rate constants and initial rates were as much as an order of magnitude greater for the 10 μm Mn reactant particle size. Additionally the activation energy was found to be 44.1 kJ mol-1 less for the 10 μm reactant particle size. Reducing the particle size had a small but positive effect on Mn-nitridation kinetics. Further reducing particle size will likely have a greater impact. A review of relevant classical thermodynamics is discussed with special attention paid to open systems. Confidence issues regarding over-reliance on x-ray diffraction are considered with options suggested for mitigation. Opportunities for future work are assessed.
Tsai, Sheng-Fong, and 蔡昇峰. "Ni-catalyzed growth of Ge and GeO2 nanostructures by the thermal evaporation and carbothermal reduction methods." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/50522118476404850748.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
96
On the thermal evaporation of Ge powders at 950˚C in Ar, the growth of Ge nanowires (GeNWs), Ge nanobelts (GeNBs), and GeO2 nanowires (GeONWs) by the Ni catalyst was studied. The Ni-catalyzed growth of GeNWs and GeNBs at 420-500˚C followed the vapor-solid-solid (VSS) process with the top-growth mode. The GeNWs and GeNBs favored the <110> and <112>, and <112>growth orientations, respectively. The surface energy plays an important role in determining the growth direction of Ge nanostructures. At higher temperatures, 600~660˚C, the first VSS growth of GeONWs was observed. This result is contrary to the previous reports that the growth of GeONWs follows the vapor-solid (VS) process regardless of the presence of metal catalysts. The growth mode of Ni-catalyzed GeNWs may be independent of the synthesis method and growth temperature. Meanwhile, the growth mechanisms of Ni-catalyzed Ge and GeO2 nanostructures are discussed. The same Ni-catalyzed growth mode of Ge and GeO2 nanostructures was also observed in the carbothermal reduction of GeO2 powders. However, the growth temperature of GeONWs raised up to 720~750˚C which are higher than that, 600~660˚C for the thermal evaporation of Ge powders.
Kumar, Rakesh. "Development And Validation Of Two-Dimensional Mathematical Model Of Boron Carbide Manufacturing Process." Thesis, 2006. http://hdl.handle.net/2005/411.
Повний текст джерелаChang, Shin-Yun, and 張詩芸. "Investigation of nanosize chromium carbide prepared by MOCVD in Fluidized Bed-carbothermal reduction process and phase evolution mechanisms." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/50587695729078655602.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
96
Nanochromium carbide were prepared by metal-organic chemical vapor deposition (MOCVD) method in a fluidized bed and carburized in the mixtures of CH4/H2 atmosphere in temperature ranged from 700-850 oC. Under these conditions, the carburization process involved carbon deposition on the outer surface of the powder, diffusion of carbon into nanopowder as well as carbide formation, Cr2O3, metastable Cr3C2-x and stable Cr3C2. The relation among the products, reduction temperature and time was summarized from the XRD. TEM is employed to investigate the detailed structure of the carbon diffusion layer. Use the STEM line scan mode to find out the compositional gradient within the interlayer: Cr3C2-x 、 Cr3C2 and pure C amorphous. The experimental results indicated that, carbonthermal reduction process of Cr2O3 consists of two steps, the rate-controlling step is CO /CO2 gas diffusion through the layer of reduction products. With the longer duration time, the stoichiometry of the mixture Cr3C2-x is the first carbide form, then to form stable Cr3C2.。 The hot-pressed Cr3C2/Al2O3 nanocomposites have better mechanical performances such as bending strength, and hardness than the monolithic Al2O3. The nano-sized Cr3C2 particles were mainly located within the Al2O3 grains as well as on the Al2O3 grain boundaries.
Bi-JrLi and 李筆智. "Study of Structural and Photoluminescent Properties of Ca3(Sc,Zn)2Si3O12: Ce3+ Green Phosphors by Carbothermal Reduction Method." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/41931299914920815128.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
101
In this study, we used the carbothermal reduction(CTR) method to produce Ca3Sc2Si3O12:Ce3+ (CSS:Ce). The CSS:Ce by CTR method was compared with that fired in air to analyze whether the optical performance could be improved or not. And then we used CTR method and added Zn2+ ions into CSS:Ce to substitute for Sc3+. We could get the Ca2.955Sc2-(2/3)xZnxSi3O12:Ce3+ (x=0~0.5) (CSZS:Ce) green phosphors. Finally, compared with Ca2.955Sc2-yAlySi3O12:Ce3+ (y=0~0.4) (CSAS:Ce), which were other CSS:Ce researches in our lab, we could analyze the relationship between the ion doping and thermal stability of optical properties. The results show the three highlights. Firstly, the luminescent intensity of CSS:Ce by CTR method was better than that fired in air. This was attributed that more Ce3+ ions were doped into the structure, which was proved by X-ray absorption spectrum and Raman scattering spectrum. Secondly, by CTR method, Zn2+ doping could effectively improve the optical performance and thermal stability. The chemical formula were Ca2.955Sc2-(2/3)xZnxSi3O12:Ce3+ (x=0~0.5). When Zn2+ doping content (x) was 0.3, the optical performance was the best. From XRD patterns, Raman scattering spectra, and FTIR spectra, it was observed that residual Sc2O3 content decreased. However, when x (Zn2+ doping content) was more than 0.2, the new impurity phase, Ca3Si3O9 (Pseudowollastonite, psW), was produced. Impurity phase could weaken the optical performance. Additionally, SEM showed Zn2+ doping brought about liquid phase sintering. Liquid phase sintering could cause samples to diffuse more uniformly in firing process and effectively improve optical performace. Thirdly, compared with Ca2.955Sc2-yAlySi3O12:Ce3+ (CSAS:Ce), which are other CSS:Ce researches in our lab, Zn2+ doping could enhance the thermal stability but Al3+ doping could not. This was attributed that Al3+ doping would decrease the activation energy of thermal quenching behavior and increase the energy of effective phonons. Therefore, the thermal stability of CSZS:Ce were better than CSAS:Ce. The above-mentioned results shows the CSZS:Ce phosphors are very excellent material as color conversion material for high power LED
Ko, Chih-Yuan, and 柯志遠. "Growth of Si1-xGexOy nanowires, and Ge/Si1-xGexOy, and GeO2/Si1-xGexOy core-shell nanowires via carbothermal reduction." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/21820389750400048760.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
94
The effects of a grown SiO2 layer on the Si substrate and the CuO additive in GeO2 powders on the enhanced growth of Ge-Si1-xGexOy and GeO2-Si1-xGexOy core-shell nanowires via carbothermal reduction at 1050-1100℃ in flowing Ar were studied. Without adding CuO into GeO2 powders only Ge-Si1-xGexOy nanowires were grown on the SiO2/Si substrate, while no nanowires could be grown on the Si substrate. Adding CuO into GeO2 powders enhanced the growth of GeO2-Si1-xGexOy and Ge-Si1-xGexOy nanowires on the Si substrate as well as that of GeO2-Si1-xGexOy nanowires on the SiO2/Si substrate. The growth of nanowires follows the vapor-solid process. The present studies reveal that the oxidation of the Si substrate plays an important role in enhancing the growth of Ge-Si1-xGexOy and GeO2-Si1-xGexOy nanowires via carbothermal reduction of GeO2 powders. The mechanisms for precipitation of Ge and GeO2 cores in the Si1-xGexOy nanowires on Si and SiO2 substrates are discussed, respectively. Upon carbothermal reduction of GeO2/CuO powders at 1100℃, not only the Ge-Si1-xGexOy and GeO2-Si1-xGexOy nanowires but also the cord-like nanowires, tubes, and chain-like wires with the chemical compositions of Si, Ge, and O were grown on the Si substrate. The tubes and chain-like wires are also composed of many Si1-xGexOy nanowires. The growth of cord-like nanowires, tubes, and chain-like wires is govern by the CuSiGe- and SiGe-catalyzed vapor-liquid-solid mechanisms, where Ge, Si, and Cu are fed from the vapor phase. For the tubes and chain-like wires the nucleation and growth of Si1-xGexOy nanowires occur on the lower surface of the droplet except the central region. As growth continues the nanowires exert a force to lift the droplet upward, forming a tubular structure. The diameters of the chain-like wires are periodically modulated. Their growth may be explained in terms of the periodic instability using the feedback mechanism. As the chain-like wire grows up, it can eventually grow into a microtube without periodic instability. The suppression of the periodic instability for the wires with larger diameter may be attributed to the decrease of the vapor supersaturation at the vapor-liquid interface due to the Gibbs-Thomson effect. In the present study, the tube can be specified as the chain-like wire with a very large wavelength.
Hwang, Yih-Chyang, and 黃意強. "The Investigation of End-of-Range Defect Reduction in Shallow Junctions Using Plasma Nitridation and Carbon Implantation." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/36325652545423249225.
Повний текст джерела國立交通大學
材料科學與工程研究所
84
The end-of-range (EOR) defects were obserced in germanium implantated Si single crystal wafer after thermal annealing. Most of the EOR defects were found to be dislocation loops of interstitial type confined to amorphous-crystalline interface. In this work, we studied the effect of plasma surface nitridation to reduce the EOR defects. Experimental resultsindicated that the Si nitride layer was able to serve as a vacancy source which, in turn, effectively reduced the size and number of the EOR dislocation loops. Another part of this work is to study the effect of carbon implantation to reduce the transient diffusion (TED) of implanted boron. It was foundthat the carbon implantation could effectively remove the EOR defects. However, hair-pin dislocations were also observed after annealing. Thehair-pin dislocations were most likely formed when the projected range (Rp) of carbon implantation was located in the vicinity of the amorphous/crystalline (a/c) interface created by Ge implantation.