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Овчаренко, Ольга Олександрівна. "Композиційні електрохімічні покриття на основі міді та нікелю, модифіковані ультрадисперсними частинками." Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/22725.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.03 – технічна електрохімія. – Національний технічний університет "Харківський політехнічний інститут", м. Харків, 2016 р.
Дисертація присвячена розробці технології композиційних електрохімічних покриттів на основі міді та нікелю, армованих нанорозмірним оксидом алюмінію. Запропоновано технологічну схему формування композитів Cu-Al₂O₃ та Ni-Al₂O₃. Запропоновано метод хімічного диспергування корунду з отриманням гідрозолю Al₂O₃. Встановлено закономірності електрохімічних процесів осадження мідних та нікелевих композиційних покриттів. Визначено вплив концентрації дисперсної фази в електролітах-суспензіях на фізико-механічні властивості матеріалів, такі як мікротвердість, межа міцності та межа текучості. Встановлено, що отримані композити мають значно вищий рівень міцності при досить низьких концентраціях Al₂O₃ в електроліті (1-2 г/дм³), у порівнянні зі зразками, отриманими з додаванням грубодисперсного оксиду алюмінію. Результати атомносилової мікроскопії дозволили визначити розмір кристалітів та оцінити топографію поверхні покриттів, встановлено вплив вмісту корунду на склад та морфологію покриттів, а результати електронної мікроскопії вказують на збереження кристалічної гратки.Thesis for granting the Degree of Candidate of Technical sciences in specialty 05.17.03 – Technical Electrochemistry. – National Technical University "Kharkiv Polytechnic Institute". Kharkiv, 2016. Dissertation is devoted to development of the technology of composite electrochemical coatings based on copper and nickel, reinforced nanoscale aluminium. The method of chemical dispersion to produce a hydrosol of corundum Al2O3 is proposed. Electrochemical processes regularities of the copper and nickel composite coatings deposition have established. The influence of a dispersed phase concentration in electrolytes-suspensions on the physico-mechanical properties of materials, such as microhardness, tensile strength and yield strength, has detected. It has shown the resulting composites have higher strength at sufficiently low concentrations in the Al₂O₃-electrolyte (1-2 g/dm³) compared with samples obtained by the introduction of the coarse-dispersion aluminium electrolyte. The influence of the corundum content on the composition and morphology of coatings has been found experimentally. The electron microscopy results detects to a continuation of a crystal lattice. The results of atomic force microscopy have allowed to determine the crystallite size and evaluate the topography of the surface. The flowchart of the electrochemical formation of Cu-Al₂O₃ and Ni-Al₂O₃ composites are proposed.
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Овчаренко, Ольга Олександрівна. "Композиційні електрохімічні покриття на основі міді та нікелю, модифіковані ультрадисперсними частинками." Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/22724.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.03 – технічна електрохімія. – Національний технічний університет "Харківський політехнічний інститут", м. Харків, 2016 р.
Дисертація присвячена розробці технології композиційних електрохімічних покриттів на основі міді та нікелю, армованих нанорозмірним оксидом алюмінію. Запропоновано технологічну схему формування композитів Cu-Al₂O₃ та Ni-Al₂O₃. Запропоновано метод хімічного диспергування корунду з отриманням гідрозолю Al₂O₃. Встановлено закономірності електрохімічних процесів осадження мідних та нікелевих композиційних покриттів. Визначено вплив концентрації дисперсної фази в електролітах-суспензіях на фізико-механічні властивості матеріалів, такі як мікротвердість, межа міцності та межа текучості. Встановлено, що отримані композити мають значно вищий рівень міцності при досить низьких концентраціях Al₂O₃ в електроліті (1-2 г/дм³), у порівнянні зі зразками, отриманими з додаванням грубодисперсного оксиду алюмінію. Результати атомносилової мікроскопії дозволили визначити розмір кристалітів та оцінити топографію поверхні покриттів, встановлено вплив вмісту корунду на склад та морфологію покриттів, а результати електронної мікроскопії вказують на збереження кристалічної гратки.Thesis for granting the Degree of Candidate of Technical sciences in specialty 05.17.03 – Technical Electrochemistry. – National Technical University "Kharkiv Polytechnic Institute". Kharkiv, 2016. Dissertation is devoted to development of the technology of composite electrochemical coatings based on copper and nickel, reinforced nanoscale aluminium. The method of chemical dispersion to produce a hydrosol of corundum Al2O3 is proposed. Electrochemical processes regularities of the copper and nickel composite coatings deposition have established. The influence of a dispersed phase concentration in electrolytes-suspensions on the physico-mechanical properties of materials, such as microhardness, tensile strength and yield strength, has detected. It has shown the resulting composites have higher strength at sufficiently low concentrations in the Al₂O₃-electrolyte (1-2 g/dm³) compared with samples obtained by the introduction of the coarse-dispersion aluminium electrolyte. The influence of the corundum content on the composition and morphology of coatings has been found experimentally. The electron microscopy results detects to a continuation of a crystal lattice. The results of atomic force microscopy have allowed to determine the crystallite size and evaluate the topography of the surface. The flowchart of the electrochemical formation of Cu-Al₂O₃ and Ni-Al₂O₃ composites are proposed.
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Ruttenberg, Eric C. "Burning characteristics of individual aluminum/aluminum oxide particles." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA315461.
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Cross, Peggi Sue 1960. "The synthesis of aluminum hydrous oxide from aluminum acetylacetonate." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277276.
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A method for the preparation of submicron, monodispersed, spherical particles of aluminum hydrous oxide has been developed. The method consists of the hydrolysis of aluminum acetylacetonate in alcoholic solution by the direct addition of a base at room temperature. The effects of the process parameters including temperature, solvent, type and concentration of base, aluminum acetylacetonate concentration, and stirring time are examined as well as the process reproducibility, particle composition and particle stability. Results obtained have shown that monodispersed particles can be formed with a mean particle diameter of eighty five to two hundred and fifteen nanometers and the mean size is reproducible to within ten percent of the mean diameter. Particles that are redispersed in fresh solvent are stable for at least thirty days. A model is proposed which explains the kinetics of particle growth and the influence of experimental parameters such as temperature, pH, concentration and the solvent on the formation of particles.
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Johnson, Robert Shawn. "Properties of Aluminum Oxide and Aluminum Oxide Alloys and their Interfaces with Silicon and Silicon Dioxide." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-20020122-104946.
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A remote plasma enhanced chemical vapor deposition method, RPECVD, was utilized to deposit thin films of aluminum oxide, tantalum oxide, tantalum aluminates, and hafnium aluminates. These films were analyzed using auger electron spectroscopy, AES, Fourier transform infrared spectroscopy, FTIR, X-ray diffraction, XRD, nuclear resonance profiling, NRP, capacitance versus voltage, C-V, and current versus voltage, J-V. FTIR indicated the alloys were homogeneous and pseudobinary in character. Combined with XRD the crystallization temperatures for films >100 nm were measured. The alloys displayed an increased temperature stability with the crystallization points being raise by >100ºC above the end point values.In-situ AES analysis provided a study of the initial formation of the films' interface with the silicon substrate. For Al2O3 these results were correlated to NRP results and indicated a thin, ~0.6 nm, interfacial layer formed during deposition.C-V characteristics indicated a layer of fixed negative charge associated with Al2O3. For Ta2O5 the C-V and J-V results displayed high levels of leakage current, due to a low conduction band offset with silicon. Both aluminates were dominated by electron trapping states. These states were determined to be due to (i) a network "break-up" component and (ii) localized atomic d-states of hafnium and tantalum atoms.
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Kokaly, Matthew T. "Grain bridging in alumina : room and high temperature /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/7107.
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Lin, Ching-Te 1967. "Microstructure, texture, and hardness gradients in aluminum diffusion-bonded to aluminum oxide." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50351.
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Smith, Michael Henry 1957. "The effects of aluminum oxide on inertial welding of aluminum in space applications." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/44393.
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Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1992 and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1992.Includes bibliographical references (leaves 126-131).
by Michael Henry Smith.
M.S.
Nav.E.
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Dogan, Ilker. "Fabrication And Characterization Of Aluminum Oxide And Silicon/aluminum Oxide Films With Si Nanocrystals Formed By Magnetron Co-sputtering Technique." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609687/index.pdf.
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DC and RF magnetron co-sputtering techniques are one of the most suitable techniques in fabrication of thin films with different compositions. In this work, Al2O3 and Si/Al2O3 thin films were fabricated by using magnetron co-sputtering technique. For Al2O3 films, the stoichiometric, optical and crystallographic analyses were performed. For Si contained Al2O3 films, the formation conditions of Si nanocrystals were investigated. To do so, these thin films were sputtered on Si (100) substrates. Post annealing was done in order to clarify the evolution of Al2O3 matrix and Si nanocrystals at different temperatures. Crystallographic properties and size of the nanocrystals were investigated by X-ray diffraction (XRD) method. The variation of the atomic concentrations and bond formations were investigated with X-ray photoelectron spectroscopy (XPS). The luminescent behaviors of Si nanocrystals and Al2O3 matrix were investigated with photoluminescence (PL) spectroscopy. Finally, the characteristic emissions from the matrix and the nanocrystals were separately identified.
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Lee, Hyungjin. "Probing Water at the Coating/Aluminum Oxide Interface." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1396545694.
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Kim, Dong-Geun. "Experimental study and thermodynamic modelling of the calcium oxide - silicon oxide - aluminum oxide - calcium fluoride system." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106562.
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Mould flux for the continuous casting process is a major concern for the steelmaking industry. Nowadays, more than 90 % of steel is being produced by the continuous casting process, which requires mould flux as an essential additive. The development of mould flux has been achieved by the conventional trial and error approach since it was first introduced in industry in the 1960s. Recently, the interest on the properties of fluorine has increased a lot since it is reported that fluorine has important functions such as playing a critical role on the crystallization behavior, and decreasing the melting point and viscosity of slag. However, the conventional way to find a suitable mould flux is not efficient to face the increasingly stringent requirements of the continuous casting process such as thin slab casting and higher casting speed. Therefore, fundamental phase diagram study on mould flux systems is clearly necessary, and thermodynamic modeling is the most effective way to design new mould flux in terms of time and money saving. The major components of mould flux, the CaO-SiO2-Al2O3-CaF2 system, are investigated in this study as these four constituents will mostly affect the largest numbers of properties. Unfortunately, fluorine has high volatility at high temperature and high reactivity with other materials. Therefore, the results of previous experiments on F-containing systems are characterized by large discrepancies due to composition alteration and unexpected reactions during the experiment. As literature data show inconsistent results between each other, key phase diagram experiments were performed in this study. The phase diagram experiments were conducted with the quenching method in sealed Pt capsules to prevent fluorine loss during the experiment. The analyses were performed using a FE-SEM equipped with an EDS system, and a newly developed technique which produces more precise quantitative results for the equilibrium phase composition. The CaO liquidus of the CaO-CaF2 binary system, which the literature data differ from each other by up to 50 mol %, was confirmed. The CaO solubility in solid CaF2 was found for the first time and reaches about 5 mol % at the eutectic temperature. The liquidus of the CaO-Al2O3-CaF2 and CaO-SiO2-CaF2 systems were carefully studied and the miscibility gap in the CaO-Al2O3-CaF2 system was proved to be much smaller than that reported in literature. Also, thermal analysis was performed using DSC in a Pt crucible. The eutectic temperatures of the CaO-CaF2 and CaAl2O4-CaF2 systems were successfully measured and the α to β-CaF2 polymorphic transition was confirmed. Based on the new experimental data and reliable literature data, thermodynamic modeling of the CaO-SiO2-Al2O3-CaF2 system was also carried out. The results of thermodynamic calculation can be very beneficial for new mould flux design.L'usage des poudres de coulée continue est une préoccupation majeure pour l'industrie sidérurgique. Actuellement, plus de 90% de l'acier est produit par le procédé de coulée continue, nécessitant impérativement l'emploi de poudres de coulée. Traditionnellement, le développement des poudres de coulée a été réalisé par la méthode d'essai et d'erreur depuis son introduction dans l'industrie dans les années 1960. Récemment, l'intérêt porté sur le fluor s'est accru car celui-ci présente d'importantes propriétés et fonctions pour le procédé de coulée continue, telles que son influence sur la cristallisation et la diminution du point de fusion et de la viscosité du laitier. Toutefois, la méthode conventionnelle de développement des poudres de coulée appropriées n'est pas efficace pour faire face aux exigences croissantes du procédé de coulée continue, telles qu'effectuer la coulée de brames minces et atteindre de plus grande vitesse de coulée. Par conséquent, l'étude fondamentale du diagramme de phase des systèmes de poudres de coulée est manifestement nécessaire, et la modélisation thermodynamique est le moyen le plus efficace pour concevoir de nouvelles poudres de coulée en termes d'économie de temps et d'argent. Les principaux composants des poudres de coulée, qui font partie du système CaO-SiO2-Al2O3-CaF2, sont examinés dans cette étude car ces quatre constituants affecteront le plus grand nombre de propriétés des poudres de coulée. Malheureusement, le fluor a une volatilité élevée à haute température et une réactivité élevée avec d'autres matériaux. Par conséquent, les résultats des expériences effectuées précédemment sur les systèmes contenant des fluorures sont caractérisés par des écarts importants en raison du changement de composition et de réactions inattendues lors des expériences. Comme les données disponibles dans la littérature rapportent des résultats contradictoires entre eux, des expériences ont été effectuées dans cette étude pour établir les diagrammes de phase. Ces expériences ont été menées avec la méthode de trempe dans des capsules de platine scellées pour empêcher la perte de fluor pendant les expériences. Les analyses ont été effectuées en utilisant un microscope électronique à balayage (MEB) équipé d'un système d'analyse dispersive en énergie de rayons X (EDS), et une technique nouvellement développée qui produit des résultats plus précis lors de la quantification de la composition des phases à l'équilibre. La courbe du liquidus du CaO du système binaire CaO-CaF2, dont les données dans la littérature diffèrent entre elles jusqu'à environ 50 % atomique, a été confirmée. La solubilité de CaO dans CaF2 à l'état solide a été trouvée pour la première fois et atteint environ 5 % atomique à la température eutectique. Les courbes de liquidus des systèmes CaO-Al2O3-CaF2 et CaO-SiO2-CaF2 ont été soigneusement étudiées et l'étendue de la lacune de miscibilité dans le système CaO-Al2O3-CaF2 a été prouvée être beaucoup plus petite que celle rapportée dans la littérature. En outre, une analyse thermique a été réalisée par calorimétrie différentielle à balayage (DSC) dans un creuset en platine. La température eutectique des systèmes CaO-CaF2 et CaAl2O4-CaF2 a été mesurée avec succès et la transition polymorphique de la forme α-CaF2 vers la forme β-CaF2 a été confirmée. Sur base des nouvelles données expérimentales et des données fiables de la littérature, la modélisation thermodynamique du système CaO-SiO2-Al2O3-CaF2 a également été réalisée. Les résultats de calcul thermodynamique peuvent être très bénéfiques pour la conception de nouvelles poudres de coulée.
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Pokrajac, Lisa A. "Fundamental studies of polyurethane - aluminum adhesion, phenyl isocyanate interaction with prepared aluminum oxide surfaces." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0006/MQ40733.pdf.
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Soleiman, Moe Karbal. "Catalytic chlorination of alpha-alumina with Cl." Thesis, Connect to this title online; UW restricted, 1986. http://hdl.handle.net/1773/15501.
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Van, Zyl Arnold. "The synthesis of beta alumina powders." Doctoral thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/17648.
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Bibliography: pages 83-90.Beta alumina solid electrolyte material is conventionally synthesized by the high temperature solid state reaction of α-Al₂O₃ with soda and a stabilizer ion such as lithia or magnesia. This reaction requires a reconstructive transformation of the α-Al₂O₃ oxygen sublattice and results in a two-phase mixture of β and β"-Al₂O. In order to maximize the preferred β"-Al₂O₃ phase an additional peak heat treatment schedule is required. This work investigated the replacement of the α-Al ₂O₃ component of the reaction mixture with a range of synthetic aluminium hydroxide precursor materials. Four different aluminium hydroxide precursors were synthesized by the controlled hydrolysis of a common aluminium isopropoxide parent material. The oxygen sublattice of each aluminium hydroxide precursor was engineered by varying the alkoxide hydrolysis conditions. These precursors were used to synthesize beta alumina powders by the high temperature solid state reaction with soda and lithia, resulting in powders with a nominal composition of Li₀.₃₈Na₁.₆₅Al₁₀.₆₆O₁₇. The solid state reactions were monitored by differential thermal analysis and thermogravimetric analysis. The structural development of the reaction products with increasing temperature, was monitored by powder X-ray diffraction. A significant observation was the direct formation of single phase β"-Al₂O₃ at 1200 °C by the solid state reaction of soda and lithia with certain aluminium hydroxides. The work concludes with the proposal of a generalized mechanism relating the aluminium hydroxide precursor oxygen sublattice to the nature of the beta alumina reaction product.
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Garza, Michelle. "Reactivity of Oxide Surfaces and Metal-Oxide Interfaces: Effects of Water Vapor Pressure on Ultrathin Aluminum Oxide Films, and Studies of Platinum Growth Modes on Ultrathin Oxide Films and Their Effects on Adhesion." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4517/.
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The reactivity of oxide surfaces and metal-oxide interfaces play an important role in many technological applications such as corrosion, heterogeneous catalysis, and microelectronics. The focus of this research was (1) understanding the effects of water vapor exposure of ultrathin aluminum oxide films under non-ultrahigh vacuum conditions (>10-9 Torr) and (2) characterization of Pt growth modes on ultrathin Ta silicate and silicon dioxide films and the effects of growth modes on adhesion of a Cu overlayer. These studies were conducted with X-ray photoelectron spectroscopy (XPS). Ni3Al(110) was oxidized (10-6 Torr O2, 800K) followed by annealing (1100K). The data indicate that the annealed oxide film is composed of NiO, Al2O3 and an intermediate phase denoted here as "AlOx". Upon exposure of the oxide film at ambient temperature to increasing water vapor pressure (10-6 - 5 Torr), a shift in both the O(1s) and Al(2p)oxide peak maxima to lower binding energies is observed. In contrast, exposure of Al2O3/Al(polycrystalline) to water vapor under the same conditions results in a high binding energy shoulder in the O(1s) spectra which indicates hydroxylation. Spectral decomposition provides further insight into the difference in reactivity between the two oxide films. The corresponding trends of the O(1s)/Ni0(2p3/2) and Al(2p)/Ni0(2p3/2) spectral intensity ratios suggest conformal changes of the oxide film on Ni3Al(110). The growth behavior of sputter deposited Pt at ~300K on Ta silicate and SiO2 ultrathin films formed on Si(100) was investigated. The XPS data show that Pt deposition results in uniform growth or "wetting" on Ta silicate and 2-D cluster growth on SiO2. Electroless Cu deposition on ~11 monolayers (ML) Pt/Ta silicate film results in an adherent Cu film which passed the Scotch tape test. In contrast, electroless Cu deposition on ~11ML Pt/SiO2 results in a non-adherent Cu film due to weak Pt/SiO2 interaction.
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Cloutier, Caroline. "The wear resistance of commercially produced aluminum oxide ceramics /." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31046.
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High hardness, fracture toughness, modulus of rupture and fine grain size are material properties that are desired for components employed in aggressive wear environments. Since aluminum oxide offers such properties, this type of material is often selected for applications that demand wear resistance. Aluminum oxide materials commercially produced at Superior Technical Ceramics were investigated to find a correlation between their mechanical properties and wear resistant performance. A pin-on-disc apparatus and a tumbling test were employed to determine the relative difference in wear between different alumina compositions. The selected 88%, 96%, 98% purple, 98% alumina and zirconia toughened alumina were subjected to four different wear tests in order to determine their wear behavior in each system. The objective was to characterize the compositions according to their mechanical properties and to establish a wear material selection guide for Superior Technical Ceramics. (Abstract shortened by UMI.)
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Magden, Emir Salih. "Rare-earth doped aluminum oxide lasers for silicon photonics." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89860.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
88
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 61-66).
A reliable and CMOS-compatible deposition process for amorphous Al2O3 based active photonic components has been developed. Al2O3 films were reactively sputtered, where process optimization was achieved at a temperature of 250°C, with a deposition rate of 8.5 nm/min. With a surface roughness of 0.3 nm over a 1 [mu]m2 area, background optical losses as low as 0.1 dB/cm were obtained for undoped films. The development of active photonics components has been realized by use of rare-earth metals as dopants. By co-sputtering aluminum and erbium targets, Er3+ dopants at concentrations on the order of 1.0x1020 cm-3 have been added to the Al2O3 host medium. Resulting Er3+:Al2O3 films have been characterized, and over 3 dB/cm absorption has been measured over a 20 nm bandwidth. Following the material development, distributed Bragg reflector lasers were designed and fabricated in a CMOS foundry. The laser cavity was created by introducing gratings on either side of a Si3N4 waveguide. Er3+:Al2O3 was deposited in SiO2 trenches on top of the Si3N4 layer, eliminating the need for any subsequent etching steps. On-chip laser output of 3.9 [mu]W has been recorded at a wavelength of 1533.4 nm, with a side mode suppression ratio over 38.9 dB.
by Emir Salih Magden.
S.M.
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Oh, Jihun. "Porous anodic aluminum oxide scaffolds; formation mechanisms and applications." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59709.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references.
Nanoporous anodic aluminium oxide (AAO) can be created with pores that self-assemble into ordered configurations. Nanostructured metal oxides have proven to be very useful as scaffolds for growth of nanowires and nanotubes with tunable diameters and with tight diameter distributions. For 50 years, field-assisted dissolution of the oxide has been cited as the mechanism that leads to pore formation in alumina, and by analogy, porous anodic TiO₂ and other functional metal oxides. We show that field-assisted dissolution models are consistent with the observed dependence of the Al₂O₃ dissolution rate on the electric field, as well as the existence of a critical field for pore initiation. However, we further show that the well-known ordered porous structure, which has a significantly different length scale, does not result from a field-induced instability, but is instead the result of a strain-induced instability with forced plastic deformation and flow of the oxide during further anodization. We demonstrate that these pore generation mechanisms can be controlled independently, even when they co-exist, by controlling the electric field across the oxide as well as the anodization conditions. We also show that mechanical confinement results in a dendritic pore structure. Through interpretation of these results we develop a generalized mechanism for ordered pore formation in AAO in analogy with cellular solidification. In addition, we report on abnormal behavior in anodic oxidation of Al in mechanically confined structures for formation of horizontal nanoporous anodic alumina oxide, H-AAO. Instead of smooth pore walls, periodic dendrite inner pore structures form, the growth rate is suppressed to 5 % of its value during bulk anodization under the same conditions, and a steady-state is never reached. These anomalies associated with formation of H-AAO originate from suppressed volume expansion and plastic flow of Al₂O₃ confined by the SiO₂ hard mask. By determining new anodization conditions leading to zero volume expansion, dendritic H-AAO can be avoided and kinetic retardation can be minimized. A new method for perforation of the AAO barrier layer has been developed, based on anodization of Al/W bilayer films on substrates. When Al/W bilayer films are anodized and pores approach the Al/W interface, tungsten oxide forms and penetrates the alumina barrier oxide, in part, due to enhanced plasticity of the alumina layer. By selectively etching the tungsten oxide, the barrier oxide can be removed and the base of the pores opened, without etching of the AAO. Finally, we further refined the selective barrier perforation process using the W interlayer to develop a methodology for fabrication of through-pore AAO scaffolds on any conducting substrate (AS) by anodizing an Al/W/AS tri-layer. Structural and kinetic study of the WO₃ extrusion revealed that the anodization of W consumes a fixed thickness of the W layer in acidic electrolytes under specific anodization conditions. Based on this study, the optimum thickness of the W interlayer in the Al/W/Au tri-layer was measured for various anodization conditions. Through-pore AAOs were fabricated on Au layers with exposure of the surface at the base of the pores, using the optimum W thickness without a violent O₂ evolution reaction and without changing the pore diameters. With scaffolds made using this methodology, vertically-aligned free-standing Au and Pt nanowires with diameters ranging from about 12 nm to about 120 nm were grown by electrodeposition on a gold substrate.
by Jihun Oh.
Ph.D.
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Krause, Benjamin Christoph [Verfasser]. "Oral uptake of aluminum and aluminum oxide nanoparticles: particle characterization and internal dose / Benjamin Christoph Krause." Berlin : Freie Universität Berlin, 2021. http://nbn-resolving.de/urn:nbn:de:kobv:188-refubium-31944-0.
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LoStracco, Gregory 1960. "Furance and carbon dioxide laser densification of sol-gel derived silicon oxide-titanium oxide-aluminum oxide planar optical waveguides." Thesis, The University of Arizona, 1994. http://hdl.handle.net/10150/291388.
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An experimental investigation on the furnace and CO₂ laser densification of sol-gel derived SiO₂-TiO₂-Al₂O₃ planar optical waveguides was performed. Solutions containing equal mole fractions of tetraethoxysiline [Si(C₂H₅O)₄], titanium ethoxide [Ti(C₂H₅O)₄], aluminum tri-sec-butoxide [Al(C₄H₉O)₃] were used to spin films with a nominal 2:2:1 molar SiO₂-TiO₂-Al₂O₃ composition. Emphasis was placed on determining what effects the densification techniques had on film shrinkage, index change, crystallization and composition. Film shrinkage and refractive index change were found to be similar for both densification techniques. Fully dense, amorphous film were obtained with both methods. After densification, further heating caused titania crystalline phases to form with both processing techniques. However, anatase formed in the furnace fired films while rutile formed in the laser irradiated films.
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Kjellander, Marcus. "Nanoporous Aluminum Oxide – A Promising Support for Modular Enzyme Reactors." Doctoral thesis, Uppsala universitet, Biokemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-210120.
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Nanoporous alumina is a rather newly characterized material that so far has found limited use in the construction of bioreactors. The material has many advantages compared to conventional immobilization matrices. I have investigated its use in flow-through bioreactors. The rigidity and porous structure of the material makes it an excellent choice for multienzyme reactor construction. The total activity in a reactor is easily controlled by the number of membranes since the porosity makes the material less prone to increase flow system pressure. This bioreactor is suitable for characterization of new enzymes since the amount of immobilized enzyme is standardized and the enzyme may be reused many times. We designed a simple stepwise technique for covalent immobilization on this matrix in a monolayer to minimize mass transfer effects in the reactor function. The kinetic parameters for ten different substrates were investigated for immobilized alcohol oxidase and, as a second step, a two-step reactor was also designed by addition of horseradish peroxidase. This bienzymatic reactor was, in turn, employed for measuring injected alcohol concentrations. The use of the matrix for substrate specificity screening was proven for two new epsilon-class glutathione transferases from Drosophila melanogaster. Immobilized trypsin showed a substantially prolonged lifetime and its potential use as an on-line digestion unit for peptide mass fingerprinting was also demonstrated. Finally, I investigated the immobilization of the model enzyme lactate dehydrogenase by adsorption mediated by metal ion chelation similar to IMAC. Regeneration was here possible multiple times without loss of capacity. In conclusion, immobilization of enzymes on nanoporous alumina is a convenient way to characterize, stabilize and reuse enzymes.
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Chan, Jimmy. "Nano-wire fabrication using anodic aluminum oxide as the template." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0002/MQ40730.pdf.
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Miller, Larry M. "Plasma enhanced chemical vapor deposition of thin aluminum oxide films." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1175717717.
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Lawson, Peter Ward 1963. "Sorption of fulvic acid on aluminum oxide and desert soil." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/191989.
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Four batch and four column experiments were conducted to investigate the sorption of salicylic acid onto aluminum oxide. Nine column experiments were performed using fulvic acid as a sorbate, and aluminum oxide and a desert soil with a low fraction organic carbon (f(OC)) ( 0.009 percent) as sorbents. Batch experiments provided estimates of partition coefficient that were eight to ten times larger than column estimates. A two-site kinetic model was used to interpret the observed tailing of breakthrough curves. Kp estimates for fulvic acid on desert soil ranged from 3 to 23 cm³/g. The time scale of the desorption reaction is 12 days. The majority of the sorption sites appear to be kinetically controlled. Results suggest that recharge of untreated Central Arizona Project water through desert washes will remove only 10-15 percent of the fulvic acid present after two void volumes have infiltrated. This may eventually contaminate existing groundwater supplies with trihalomethane precursors.
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Spencer, Darryl Day. "The importance of aluminum oxide aerosols to stratospheric ozone depletion." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41371.
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Norwood, Sasha Norien. "Characterization of Nano-scale Aluminum Oxide Transport Through Porous Media." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/981.
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Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations of emerging contaminants (e.g. pharmaceuticals, personal care products) while containing a significant fraction of inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum.
Given their reactivity and small size, there are many questions concerning the potential migration of these nano-sized colloidal materials through the soil column and into our surface and groundwater bodies. Transport of emerging pollutants of concern through the soil column, at minimum, is impacted by colloidal properties (e.g. chemical composition, shape, aggregation kinetics), solution chemistry (e.g. pH, ionic strength, natural organic matter), and water flow velocity. The purpose of this current research was to characterize the long-term transport behavior of aluminum oxide nanoparticles (Al2O3) through a natural porous media with changes in pH, aqueous-phase concentration, pore-water velocity and electrolyte valence. Additionally, deposition rates during the initial stages of deposition were compared to several models developed based on colloid filtration theory and DLVO stability theory. Benchtop column laboratory experiments showed that, under environmentally relevant groundwater conditions, Al2O3 nanoparticles are mobile through saturated porous media. Mobility increased under conditions in which the nanoparticles and porous media were of like charge (pH 9). Changes in linear pore water velocity, under these same high pH conditions, showed similar transport behavior with little mass retained in the system. Deposition is believed to be kinetically controlled at pH 9, as evidenced by the slightly earlier breakthrough as flow rate increased and was further supported by observed concentration effects on the arrival wave following several stop flows.
While lower aqueous-phase concentrations resulted in significantly longer breakthrough times, the total mass retained in the system was found to be independent of concentration. Additionally, experimental deposition rate coefficients (kd), used to describe deposition kinetics under "clean bed" conditions, were similar across the aqueous-phase concentrations studied. The use of calcium chloride electrolyte solution in transport studies resulted in enhanced mobility relative to potassium chloride suggesting that changes in groundwater solution chemistry could impact mobility of contaminants associated with biosolids. Predicted deposition rate coefficients, using three different models, were found to under- or over-predict values relative to those experimentally determined values depending on the model. This current research has shown that nanocolloids associated with biosolids, specifically Al2O3, are mobile through saturated porous media. Given the ubiquity of nanocolloidal materials, particularly engineered nanomaterials, coupled with the expected increase in land-application of biosolids, a clear understanding of their transport and fate is prudent to understanding the potential impact these emerging pollutants may have on our surface and groundwater bodies.
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Chen, Xi Gui, and 陳錫圭. "Carbothermic nitridation of aluminum oxide." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/55761732262028661873.
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Liu, Cheng-he, and 劉政和. "Hydrothermal synthesis of aluminum oxide." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/09979425292670906801.
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碩士義守大學
生物技術與化學工程研究所碩士班
97
This study utilized continuous hydrothermal synthesis to produce flake boehmite with various morphology and size and spherical aluminum oxide.Based on the difference of heating,this study concluded that: (1) Produced by direct heating: 1.By up-flowing reactor,hexagonal flake of boehmite was obtained,and its mean size was 0.7 ~1.0 um.; 2.By down-flowing reactor,long hexagonal flake of boehmite was obtained, and its mean size was 1.43~2.69 um; 3.Morphology and size of the boehmite was mainly affected by the residence time in hydrothermal condition; 4.Flake boehmite without agglomeration can be obtained in the range of 220~290 C with 0.01 M of aluminum nitrate solution as the nutrition. (2) Produced in Supercritical Water Flame 1.Morphology of the produced boehmite was mainly determined by temperature.Aluminum oxide was obtained as temperature higher than 420 C,and only boehmite was found as lower than 420 C. 2.Nucleation occurred right after hydrolysis.Particles grow as temperature increases because of decrease of solubility of boehmite in acidic environment.While the growing particles were cooled after temperature passed over the critical temperature,the dramatic decrease of solubility could lead to another additional nucleation.Therefore,the obtained particles could show bimodal distribution.This was observed,if temperature of the supercritical water flame was ranged from 400 to 420 C. 3.While temperature of the supercritical water flame was below 400 C,the solubility of boehmite in acidic was higher than that in alkaline environment.Therefore the particle was remained its size as grown at high temperature.A little larger and much narrower particle of boehmite could be obtained.
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Sheedy, Paul Martin. "Effects of aluminum and zirconia contents on the reaction bonded aluminum oxide process /." Diss., 2002. 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:3073993.
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Johnson, Robert Shawn. "Properties of aluminum oxide and aluminum oxide alloys and their interfaces with silicon and silicon dioxide." 2001. http://www.lib.ncsu.edu/etd/public/etd-319152401024230/etd.pdf.
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Chen, Chi, and 陳琪. "Electrowetting of Hydrophobic Anodic Aluminum Oxide." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/61835654382023375399.
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碩士國立交通大學
材料科學與工程學系
100
A two-step anodization process is emoployed to fabricate a self-organized nanoporous anodic aluminum oxide (AAO) on aluminum film. The resulting AAO structure displays adjustable thickness and pore size contingent on the processing parameters. For Electrowetting on Dielectric(EWOD) testing, the as-prepared AAOs with different morphologies are first surface-modified by fluoroalkysilane（FAS-17）to render desirable hydrophobicity. Subsequently, an AC electrical field is imposed across a droplet and the AAO sample in which the solid/liquid interface experiences a dramatic change in charge density, resulting in the switching of wettability from hrdrophobic state to hydrophilic one. We investigate the EWOD effects on a variety of AAO samples with various thickness and pore diameters. To understand the wettability transition, a capillary-pressure balance model is proposed to estimate the depth of water penetrating into the AAO pore channels.
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Chien, Wei-han, and 簡韋瀚. "Optical Application of Anodic Aluminum Oxide." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/02799147035286527615.
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碩士國立中山大學
光電工程研究所
95
Abstract The AAO membrane with nanopore arrays were fabricated by anodizing highly pure aluminum foils (99.9995%) in electrolyte under steady voltage. Pore diameter can be controlled by different anodic voltage(from 30 to 50 V) and electrolyte, on the other hand, thickness is proportioned to anodizing time , and interpore could follow this rule(a = 15.4+2.63×v) , and minimum radius of pore could reach 15nm . The XRD spectra of AAO without and with annealing, both showed the diffraction peaks of (311)、(400)、(440), corresponding to the γ-Al2O3 phase . Before fabricating AAO, we would polish under low temperature and then clean alumina foil in order to reduce surface roughness that is good for better order and regular. Through the use of porous anodic alumina masks, Au nanodot arrays deposited on Si by E-gun with AAO mask. Subsequently, the AAO mask was removed by H3PO4. Under the same procedure, we can fabricate 80nm of the diameter of pore and apply this mask on wafer of laser constructure . Because of regular hexagonal pore array, we may get the photonic crystal effect. During PL experiment, we got the result that AAO could increase light extraction of quantum dot from C237 wafer and controlled emission peak from C238 and C196 wafer and position of peak could shift to 1140nm. We hope nanodot array on wafer of laser structure could control emission peak.
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Stamatis, Demitrios. "Fully dense aluminum-rich aluminum copper oxide powders for energetic formulations." Thesis, 2008. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2008-026.
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Chen, Peng-Yu, and 陳鵬宇. "Aluminum oxide layer prepared by plasma oxidation on single-crystalline aluminum film." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/q3e939.
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碩士國立交通大學
電子研究所
105
In this thesis¸ the plasma oxidation on single-crystalline Aluminum is presented. The dependence of oxidation rates on the N2O flux, the substrate temperature, the RF power, and the chamber pressure is studied with Auger Electron Spectroscopy (AES) , Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM). The dependence of oxide thickness and oxidation time is plotted, and also compared to the mathematic model in thermal oxidation. In this thesis, the Al2O3 is applied to gate oxide in GaAs MOSFET. The I-V characteristic of MOSFET is studied, and the interface quality is checked by X-ray Photoelectron Spectroscopy (XPS). Our work provides another way to prepare a smooth nano-scale Al2O3 film on aluminum, and we are hoping that this fabrication process of plasma oxidation will be improved in future.
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sheng, Peng jing, and 彭及聖. "Control porous pattern of anodic aluminum oxide." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/87355058402729631449.
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碩士國立中興大學
機械工程學系
93
In this research, a series of anodic aluminum oxide fabrication experiments based on the aluminum foils laminate approach were carried out. During the experiments, we found that the pores of the AAO grew only on the upper foil, bi-directionally from both the top and the bottom surfaces. Experimental results further indicate that the upward porous pattern of the upper foil is determined by the surface structure of the bottom surface of the upper foil. The porous pattern of AAO can be controlled by a pre-made pattern on the bottom surface. In addition, since the lower aluminum sheet attached to the bottom of the being anodized aluminum sheet acts as a barrier layer during anodization, no barrier removing process is required in this novel laminate approach. The developed work in this study can be further applied to the fabrication of nanofunction devices.
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Chen, Ling-Chia, and 陳凌嘉. "The Fabrication of Suspend Aluminum Oxide Film." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/63241963785442757439.
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碩士和春技術學院
電機工程研究所
95
This thesis propose a way to make the Bulk Micromachining substrate of MEMS by wet etching. The sacrificial layer be derived by photo-resist coating techniques of MEMS. The aluminum thin films were deposited on silicon substrate by evaporator, and then sacrificial layer be removed, the suspended aluminum thin films were derived. The suspended aluminum thin film was proceeded the high temperature metal oxidizing. We can get the aluminum oxide thin films and analysis the selective effect of suspended films properties.
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Tsai, Yu-wei, and 蔡育瑋. "Process Parameters Optimization of Anodic Aluminum Oxide." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/09360102360948758619.
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碩士國立高雄第一科技大學
電機工程研究所碩士班
102
The purpose of the study is to optimize the anodic aluminum oxide conversion efficiency. The experiment of the study is divided into two parts using Taguchi Method。The control factorsfor the first part of experiment are annealing temperature (A), the annealing time (B), the dimensions of the magnet (C) and the magnet speed (D). The control factors for the second part of experiment are annealing time A, annealing temperature (B), size of the magnet(C) , magnet rotation speed (D), the voltage (E), the concentration of phosphoric acid (F), the concentration of oxalic acid (H) and the temperature (G). By the design of orthogonal array L9 (34) and L18 (21 * 37) , two groups of conversion efficiency of nine and eighteen, respectively, are obtained. The best parameter factors are achieved by the S/N ratiosof the greatest quality characteristics,. We use high-purity aluminum (99.98%) as the substrate. The aluminum substrate is annealed before aluminum anodization experiment, The annealing time, annealing temperature and the aluminum anodization conditions are chosen according to the orthogonal array and then the conversion efficiency result from 1.1 to 1.96 by the division of the formed AAO weighing divided by the weight of consumed aluminum multiplied a mole weight factor. The experimental range of control factors : the annealing temperature was 400 ° C ~ 600 ° C, time was 30min ~ 60min, magnet size was 1.5cm ~ 2.5cm, magnet speed was 80rpm ~ 120rpm. The other control factors as voltage, the concentration of phosphoric acid, oxalic acid concentration and temperature III parameters adopted the same value as previous optimal results. The effects of control factors are analyzed using the signal-to-noise (S/N) ratio and the analysis of variance (ANOVA). According to the results, annealing temperature play the significant role on the conversion efficiency of anodic aluminum oxide. Furthermore, the estimated optimum values of the process parameters are corresponding to anodizing voltage of 160 V, phosphoric acid of 1.1 M, oxalic acid of 0.14 M, and electrolyte temperature of 2 °C. Finally, the optimized parameters factors laser heat treatment, γ-Al2O3 phase transformation of α-Al2O3 phase, analyzed and discussed. Key word:
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Chen, Po-chen, and 陳柏辰. "Thermally Formed Oxide Films of (Al-XSi, Al-YMg) Aluminum Alloys and the Pure Aluminum Anodic Oxide Growth Behavior." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/85072157238330712130.
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博士國立中央大學
機械工程研究所
98
This thesis aimed at investigating thermally formed oxide films on aluminum alloys heated in different gases and hydrogen content on development of anodic aluminum oxide growth behavior. The study can be divided into two main parts. First, the thermally formed oxide films on Al-XSi and Al-YMg alloy heated in different gases. Second, the effects of hydrogen content on development of anodic aluminum oxide film on pure aluminum were observed. Part I: Thermally formed oxide films on Al–XSi, Al-YMg alloys heated in different gases. The XRD, EPMA and TGA analysis testing was used to polished samples of Al–XSi and Al-YMg alloys. The thermally formed surface oxide films on the Al–1.2wt% Si alloy samples heated in air and in nitrogen gas possessed loose structures, which comprised mainly γ-alumina, Diaspore, and Gibbsite, along with metallic silicon and/or aluminum. Weight changes in Al-2 and 3.5wt% Mg samples were first heated in a dry air atmosphere. The oxide film formed on the Al-2wt% Mg sample comprised γ-alumina, MgO, Spinel and Gibbsite. The film formed on the Al-3.5wt%Mg sample contained large quantities of MgO, but no Spinel. The samples were then heated in a nitrogen gas atmosphere for <1.9 h. The Al-3.5wt% Mg sample contained greater amounts of Gibbsite and γ-alumina than did the Al-2 wt% Mg sample. The latter yielded a greater amount of AlN (and/or MgO). After an extended holding time (~6 h), the Al-3.5wt% Mg sample contained a greater amount of AlN (and/or MgO), and its weight increased remarkably. Part II: The effect of hydrogen content on development anodic aluminum oxide growth behavior. To ensure constant current densities, voltage-time (V-t) curves were recorded during the experiment. The differential ΔV/Δt curves were plotted in order to compute the energy consumed at different steps of anodization. Experimental observations showed that differences in hydrogen content affected the energy consumed in 3 steps in the process that we defined. When the voltage response at the end of step 2 exceeded 25 V, the energy consumed in steps 2 + 3 reached or exceeded 7.4 J/cm2, and the pore channels branched or merged, creating a spike in the ΔV/Δt curves in step 3. Combining the effects of the high voltage response at the end of step 2 and the high hydrogen content in the Al samples, the anodic aluminum oxide (AAO) film formed in the sulfuric acidic solution, produced crystallized boehmite. This study proposes a unique tool for understanding certain special anodic behaviors of pure Al from which the branching or merging of pore channels and the partial crystallization of the AAO film can be ascertained via irregularities in ΔV/Δt curves obtained in step 3.
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SYU, WEI-SYUAN, and 徐偉軒. "Indium Tin Oxide/ Aluminum Zinc Oxide Films Applied in Low Emissivity Glass." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/08105276921180646637.
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碩士崑山科技大學
電機工程研究所
103
Bi-layered indium tin oxide/aluminum doped zinc oxide (abbreviated as ITO/AZO) films were produced by in-line sputtering. Two different concentrations of oxygen gas flow: 1.88 and 3.33% were applied during producing indium tin oxide films. The ITO/AZO films with 1.88 % oxygen concentration can have 9.8X10-4 ohm-cm in electric resistivity and 75% in average optical transmittance (in region of 400~700 nm) Vacuum and hydrogen plasma annealing was treated on ITO/AZO films. Both vacuum and hydrogen plasma annealing can improve electrical and optical properties of ITO/AZO films. Hydrogen plasma annealing can improve more on electrical and optical properties of ITO/AZO films than vacuum annealing does. Hydrogen plasma annealed ITO/AZO films with 1.88 % oxygen concentration can have 3.6X10-4 ohm-cm in electric resistivity and 89% in average optical transmittance (in region of 400~700 nm). The as-deposited, vacuum and hydrogen plasma annealed ITO/AZO films were measured in optical reflectance in infrared region for evaluating ITO/AZO films applied in low emissivity glass. The optical reflectance at 2500 nm for vacuum and hydrogen plasma annealed ITO/AZO films is around at 69 %; which is more than 3 times compared with that for as-deposited ITO/AZO films. This result indicates vacuum and hydrogen plasma annealed ITO/AZO films have high potential applied in low emissivity glass
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Yeh, Kuo-yu, and 葉國裕. "The effect of aluminum heat treatment on the growth of aluminum oxide film." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/17782731386474850411.
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碩士大同大學
化學工程學系(所)
93
This research is to investigate the surface conditions and mechanical properties of the oxidized films of the aluminum materials after annealing then anodized in an electrolyte containing sulfuric acid, expecting that by taking the advantages of heat treatment, better aluminum oxide layer can be obtained. From the results, it was discovered that after the annealing treatment at given temperature, because of the rearrangement of the surface crystalline structure, the growth produce of the film can be accelerated and the growth condition of the surface can be improved. From the analysis of X-ray diffraction, it is known that the crystalline produced after the heat treatment is ��-Al2O3; ��-Al2O3 would produce effect on both the density and hardness of the aluminum oxide film, and would slow down the dissolution rate of the film. In addition, it is found that after the preimmersing treatment with ammonium molybdate, because of the adjustment of the properties of crystalline structure of annealing treatment, the inhibition of the molybdic oxyhydroxide film is decreased, and the growth of the aluminum oxide film is promoted, causing the film thickness to be improved.
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Smith, Michael Henry. "The effects of aluminum oxide on inertial welding of aluminum in space applications." Thesis, 1992. http://hdl.handle.net/10945/23873.
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Hsu, Chih-Yu, and 許芷瑀. "electrochemical synthesis of nanowires in anodic aluminum oxide." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/18499495714114365418.
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碩士國立中央大學
化學研究所
95
The anodic aluminum oxide (AAO) was prepared from high-purity (99.99%) aluminum foil in 0.3M oxalic acid electrolyte by a two-step anodization process. The anodic aluminum oxide (AAO) with pore size 60 nm and channel length 90 μm was used to fabricate pure bismuth and cobalt nanowires. A Au layer was sputtered on one side of the anodic aluminum oxide (AAO) to serve as the working electrode in a standard three-electrode electrochemical cell. Solutions of 0.008M bismuth nitrate and 0.14M cobalt sulfate heptahydrate were used as electrolytes of the electrodeposition process of the Bi and Co nanowires respectively. The potentiostatic electrochemical deposition of Bi and Co nanowires were performed with -0.15 V and -1.0V respectively. Diameters of the Bi and the Co nanowires were 60 nm and 75 nm respectively. The Physical Property Measurement System (PPMS) and Superconducting Quantum Interference Device Magnetometer (SQUID) were used to measure the resistance and magnetic properties of Co nanowire.
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Wu, Chen-Yu, and 吳鎮宇. "Memory Effect in Sputtered Aluminum Oxide Thin Films." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/99994196806794273184.
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碩士國立交通大學
電子工程系所
95
In this thesis, next-generation nonvolatile memory will be introduced and from those we focus on resistance random access memory (RRAM) research. The RRAM has bistable resistive switching characteristic which can exhibit two states of different resistance for logic level. Therefore, RRAM can be next-generation memory by this characteristic. Owing to RRAM has excellent characteristics of high-speed operation, low-power, and high-density integration. In addition, its simple cell structure (metal-oxide-metal tri-layer), CMOS-friendly materials and low process temperature all are advantages for next-generation memory application. RRAM is fabricated with aluminum oxide thin film deposited on Pt bottom electrode by RF magnetron sputter and chose Ti for top electrode. First, some material analyses of aluminum oxide thin films are proposed. The physical, electrical properties and reliability issue of RRAM are observed. From those analyses, conduction mechanism and switching mechanism could be driven. Finally, a solvent is proposed to improve the disadvantage of electrical characteristics for our device. It made the device potential for next-generation memory application
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Lee, Yi-Pei, and 李宜珮. "Studies of Aluminum Hydroxide and Cuprous Oxide Nanoparticles." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/10737764749158964059.
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碩士國立成功大學
化學系
87
The 532nm wavelength of a pulsed laser was used to irradiate the aluminum rod, which was immersed in H2O. Immediately after preparation, the amorphous-spherical particles were acquired in solution. Then, the dissolution and recrystallization process was proceeding to form crystalline aluminum hydroxides. The morphological appearance consists of triangle (bayerite), rectangle (gibbsite), and fibrous shapes (boehmite). The formation mechanisms from Al bulk phase to aluminum hydroxide particles have been discussed. The effects of the pH values and the temperatures were examined for the growth of Al(OH)3 particles, as well. CuO powders were irradiated in water by a laser using 532nm wavelength. The cuprous oxide particles formed as spindle shapes were observed from TEM images. The morphology of cuprous oxides became spherical-like by additional irradiation. The studies of the cuprous oxides have been performed on the basis of the laser wavelengths and pulse energies.
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Liu, Tze-chun, and 劉澤鈞. "Gas Microsensors Based on Nanoporous Anodic Aluminum Oxide." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/29622697040391545281.
Full textAbstract:
碩士逢甲大學
自動控制工程所
99
A novel CO gas microsensor with tungsten oxide (WO3) sensing film on nanoporous anodic aluminum oxide (AAO) layer has been performed on anodic aluminum oxide template at operation temperature of 25 ℃. Based on microelectromechanical system (MEMS) technology, the microstructures are realized with porous AAO template, WO3 thin films, heaters, and interdigital temperature sensors. The platinum films were deposited to form the heaters, temperature sensors, and interdigital electrodes. To enhance sensitivity, the sputtered WO3 was grown on various nanoporous AAO structures. The study develops a novel porous anodic alumina processing system with a functional current feedback control module that provides control different conditions of voltage, temperature, and etching time to obtain uniform size of AAO film in the range from 20 nm to 104 nm. The self-ordered alumina membranes with a wide range of pore sizes are also achieved to increase sensing area of the microsensor. Experimental results are analyzed to find the relationship between the CO gas concentrations, the characterization of sensitivity and operational temperatures. Compared to traditional gas sensors, the designed CO gas microsensors show higher sensitivity by increasing variation of sensing resistance up to 87.4 % by sensing CO gas concentrations from 100 to 1000 ppm.
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Yu, Cheng-En, and 余成恩. "Preparation and characterization of anodic aluminum oxide templates." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/65450094327927650570.
Full textAbstract:
碩士國立中正大學
化學工程所
94
Formation of porous anodic aluminum oxide (AAO) templates on industrial aluminum substrates in sulfuric acid and oxalic acid solution was systematically investigated in this work. To fabricate self-ordered aluminum oxide films, the anodizing conditions, pre-treatments of substrates, and the surface roughness of aluminum substrates were also investigated in this work. First, we find the relationship between the formation voltage and the pore structure of AAO films under constant cell voltage in the sulfuric acid solutions. Aluminum sheets were pre-treated by three different methods to form more ordered AAO films. To obtain the best eletropolishing conditions for getting the lowest surface roughness aluminum substrate, the fractional factorial design was employed. From the results of experiment designs, the key variables affecting the surface roughness were cell potential, anodizing time, and reaction temperature. In the conforming experiments, the interaction between cell potential and anodizing time was found to significantly affect the quality of AAO films. In respect of electrochemistry of AAO formation, and establishing the relationship between the surface roughness of aluminum substrate and the porous structure of AAO films, current-time responses for the first step anodization were recorded. And recognize the regularity of the anodic aluminum oxide preliminarily by the electrochemical behavior. The characterizations of anodic aluminum oxide template and the pre-treated aluminum substrate were carried out by SEM and AFM.
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LAO, WEI LI, and 勞煒立. "Study of Aluminum oxide for anti-voltage resistance." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/20574250130847922871.
Full textAbstract:
碩士高苑科技大學
高分子環保材料研究所
96
Anodizing oxidation method was employed to treat aluminum substrate in order to get an insulating surface by form a layer of aluminum oxide (A12O3) film under the oxidation condition of using sulfuric acid, oxalic acid, mixed acid solution (sulfuric acid and oxalic acid), tartaric acid and malonic acid as the electrolytes, respectively. Microstructures of thin films prepared by different oxidation conditions were analyzed by Scanning Electron Micrograph (SEM); dielectric properties were evaluated using high resistance meter and voltage resistance meter respectively. Experimental results show: (1) The aluminum oxide films are prepared by 100g/L tartaric acid, 100g/L malonic acid, 20g/L oxalic acid, respectively, those could be annealed in the 400˚C without cracks. (2) The above three aluminum oxide films have different anti-voltage resistance. 2000V is observed in 100g/L tartaric acid solution; 1700V is observed in 100g/L malonic acid solution; and 500 V is found in 20g/L oxalic acid. (3) Lots of acicular substance on surface of films under the oxidation condition of solution of 4% concentration, diameter of which is about 80nm, may be hydrates of Al(OH)3 absorbed on surface of films. (4) The inner aluminum oxide layer is structured by sulfuric acid, and the outer aluminum oxide layer is formed by tartaric acid, malonic acid and oxalic acid. Hence, the inner stress is presented in the annealing condition to lead cracks. Under the condition of malonic solution of 100g/L，the aluminum oxide film has anti-voltage resistance at 2000V and anti-thermal character in 400˚C.
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TIEN, TU-CHIN, and 田祐晉. "Preparation of Solution-Processed Aluminum Oxide Gate Dielectric." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/5cam23.
Full textAbstract:
碩士國立臺南大學
材料科學系碩士班
106
Thin film transistors (TFTs) are important electronic components that can be used as display pixel switches, memory, light sensors, and biochemical sensors. In this study, the AlOx film was prepared by solution method. It is hoped to replace the traditional germanium dioxide (SiO2) as the gate dielectric layer to improve the device characteristics of the thin film transistor. The dielectric layer precursor used in the experiment is dissolved in aluminum oxide. The solution of the alcohol methyl ether, the channel layer precursor liquid is a solution of zinc nitrate and tin chloride dissolved in ethylene glycol methyl ether, and the aluminum oxide dielectric layer and the zinc tin oxide channel layer are respectively prepared by a spin coating method. In this study, the X-ray diffraction results show that the AlOx film prepared by the experiment is amorphous by changing the annealing temperature. Through the measurement of the precision impedance analyzer (Agilent 4294A), it is found that amorphous AlOx can effectively reduce the leakage current caused by the grain boundary compared with the conventional crystalline SiO2, and the capacitance value of 1 MHz at the annealing temperature of 450℃ can be Up to 417(nF/cm2). At the same time, this experiment also applies different concentrations of precursor liquid (0.1M, 0.6M), and the amorphous alumina surface is modified in different ways. Finally, the component characteristics after the reforming treatment will be discussed.
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Wei, Pai-Sheng, and 魏百盛. "Thermally-Formed and Anodic Aluminum Oxide Growth Behavior." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/60587544804064466839.
Full textAbstract:
博士國立中央大學
機械工程研究所
96
This thesis aimed at investigating alumina oxide film formed on aluminum, which is the most popular light metal applying to many common purposes. The study can be divided into three main parts. First, the observation of thermally-formed aluminum oxide on pure aluminum was conducted. The formation of pores and microbubbles derived by hydrogen in aluminum was brought out. Second, the anodic oxide films formed on aluminum were observed. In the part of this study, we measured and recorded the potential and processing time during anodizing treatment performed in different substrate. There are some critical points on the differentiated curves (ΔV/Δt) obtained from the measured data which most likely correspond to micropore initiation and pitting formation. Some more subjects about anodic oxide film were presented. Third, Optical properties of anodic aluminum oxide films on Al1050 and Al5052 alloys were investigated. The individual briefs are as following: PartⅠ: Pure aluminum (99.999%) cubes were polished by abrasive papers then heated in furnace at 873K for 25 hr to grow oxide on the polished surfaces and coded as Al/oxide. The thermally-formed oxide was investigated with SEM and G.I.A in order to reveal the structure of oxide. These Al/oxide samples were stacked with pure Al cube and Al-7mass%Si cube respectively then heated in furnace at 1023K for 1200 s in an Ar+H2 atmospheric gas. The sandwich samples were sectioned and polished after the heated sample cooled to room temperature. The morphologies of interface (or junction of the sandwich samples) were recorded photographically. Based on the recorded cavities shown at the interface, we measured both the radii of curvatures and contact angles of cavities. When the Al/oxide stacking with pure Al sandwich samples heated in Ar plus H2 gas, cavities were readily shown at the interface; very few cavities has been observed when samples heated in Ar gas. Air-pocket initiated at the microchannels by hydrogen diffusion then grew and coalesced at the interface. The air-pockets remained at the interface of heated Al/oxide stacking with pure Al sandwich sample and entrapped as cavities after samples solidified. Microbubbles detached from the airpocket forming micropores trapped in matrix of the Al/oxide stacking with Al-7mass% Si cube sample. PartⅡ: The formation behavior of anodic oxide film formed on aluminum was observed. In this part the relation of the anodic potential versus processing time was recorded for the anodizing of an Al1050 aluminum sheet in a sulfuric acid solution. The electrochemical behavior of aluminum during the anodizing treatment can be characterized by measuring the anodic potential-time curves. The nanostructure of anodic films was observed with transmission electron microscopy (TEM) and high resolution Field-Emission Scanning electron microscopy (SEM). The differentiated curves (ΔV/Δt) could be partitioned into four steps indicating the processing conditions during the growth of the anodic film: barrier layer formation, nanopore initiation and growth, pore widening, and quasi-steady state growth of the anodic film. Pitting during the pore widening stage could be characterized by looking at the different types of valleys in the differentiated curve. The effects of the anodic parameters, such as the acid concentration, bath temperature, current density and impurities, on pitting formation were investigated and some conclusions offered. PartⅢ: A spectrophotometer was used to measure the surface reflectance of AAO films, which formed from the different processing conditions on Al1050 and Al5052 alloys. The factors that affected the reflectance of AAO film were discussed. After cleaning and desmutting Al1050 and Al5052 alloys sheets were anodized in a 15% w/w sulfuric acid solution at 1.2-1.8 A*dm-2 and 283~303K. The potential-time curves were recorded during the anodizing process. The nano-structure of the AAO films changed with the anodic current density and the bath temperature. The area fraction of nano-pores on the anodic film increased with increasing bath temperature and with decreasing anodic current density. A spectrophotometer was used to measure the surface reflectance of AAO films, which formed from the different processing conditions. The factors that affected the reflectance of AAO films are discussed.
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Sheng, Pei-Sun, and 盛焙蓀. "Anodic Aluminum Oxide Assisted Preparation of Silica Tubes." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/79507500284085862524.
Full textAbstract:
碩士國立交通大學
應用化學系
91
Si/SiO2 tubes were successfully synthesized by using SiCl4 as a precursor to react with Na tubes which decomposed from NaH and flowed into AAO channel. The diameter of the synthesized Si/SiO2 tubes consist with that of AAO channels. The samples were characterized by SEM, TEM, EDS, ED, IR, XRD and XPS to examine the morphology and composition. SEM studies indicated that the tubes with porous walls were found at the reaction temperature of 623 K and annealing temperature of 873 K. From EDS analysis, those tubes consisted of Si and O elements. ED and XRD studies showed that the tubes were amorphous, and Si-O-Si absorption was observed by IR. According to the XPS data, there were two types of chemical environment for Si in this sample — Si and SiO2. The Si/SiO2 tubes were oxidized futher by O2 stream to form pure SiO2 tubes. The reason of forming the pores on the wall was detemined by EDS and XRD, it is speculated that NaCl was formed during the reaction to insert on the wall, and dissolved with HCl solution for removing AAO membranes.