Дисертації з теми "Aluminum alloy coating"
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Jain, Syadwad. "Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate and cerium inhibitors." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1145140821.
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KOTTARATH, SANDEEP. "PROCESSING & PROPERTIES OF CLAY-ICP/POLYIMIDE NANOCOMPOSITE COATINGS ON ALUMINUM ALLOY." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1097454077.
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Goetz, John M. "Investigation of coating cracking and fatigue strength of 7050-T74 aluminum alloy with different anodize coating thicknesses." Connect to this title online, 2005. http://hdl.handle.net/1811/327.
Повний текст джерелаАнотація:
Thesis (Honors)--Ohio State University, 2005.Title from first page of PDF file. Document formattted into pages: contains v, 40 p.; also includes graphics. Includes bibliographical references (p. 39-40). Available online via Ohio State University's Knowledge Bank.
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Xu, Hong. "Magnesium Alloy Particulates Used as Pigments in Metal-Rich Primer System for AA2024 T3 Corrosion Protection." Diss., North Dakota State University, 2010. https://hdl.handle.net/10365/28378.
Повний текст джерелаАнотація:
As an alternative to the present toxic chromate-based coating system now in use, the Mg-rich primer technology has been designed to protect A1 alloys (in particular A1 2024 T3) and developed in analogy to Zn-rich primers for steel substrate. As an expansion of this concept, metal-rich primer systems based on Mg alloy particles as pigments were studied. Five different Mg alloy pigments. AM60, A719B, LNR91, AM503 and AZG, were characterized by using the same epoxy-polyamide polymer as binder, a same dispersion additive and the same solvent. Different Mg alloy-rich primers were formulated by varying the Mg alloy particles and their pigment volume concentrations (PVC). The electrochemical performance of each Mg alloy-rich primer alter the cyclic exposure in Prohesion chamber was investigated by electrochemical impedance Spectroscopy (EIS). The results indicated that all the Mg alloy-rich primers could provide cathodic protection for AA 2024 T3 substrates. However, the Mg alloys as pigments in metal-rich primers seemed to exhibit the different anti-corrosion protection performances, such as the barrier properties, due to the different properties of these pigments. In these investigations, multiple samples of each system were studied and statistical methods were used in analyzing the EIS data. From these results. the recommendation for improved EIS data analysis was made. CPVC studies were carried out on the Mg alloy-rich primers by using three Mg alloy pigments, AM60, A2918 and LNR91. A modified model for predicting CPVC is proposed, and the results showed much better agreement between the CPVC values obtained from the experimental and mathematical methods. Using the data from the AM60 alloy pigment system, an estimate of experimental coarseness was done on a coating system, the first time such an estimate has been performed. By combining various surface analysis techniques, such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and confocal Raman microscopy, the oxidation products formed alter exposure were identified. It was found that variation of A1 content in Mg alloy could significantly affect the pH of the microenvironment in the primer films and result in the formation of various oxidation products.Air Force Office of Scientific Research (AFOSR) (Grant No. 49620-02-1-0398)
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Xu, Hong. "Magnesium Alloy Particulates used as Pigments in Metal-Rich Primer System for AA2024 T3 Corrosion Protection." Diss., North Dakota State University, 2011. https://hdl.handle.net/10365/28838.
Повний текст джерелаАнотація:
As an alternative to the present toxic chromate-based coating system now in use, the Mg-rich primer technology has been designed to protect Al alloys (in particular Al 2024 T3) and developed in analogy to Zn-rich primers for steel substrate. As an expansion of this concept, metal-rich primer systems based on Mg alloy particles as pigments were studied. Five different Mg alloy pigments, AM60, AZ91B, LNR91, AM503 and AZG, were characterized by using the same epoxy-polyamide polymer as binder, a same dispersion additive and the same solvent. Different Mg alloy-rich primers were formulated by varying the Mg alloy particles and their pigment volume concentrations (PVC). The electrochemical performance of each Mg alloy-rich primer after the cyclic exposure in Prohesion chamber was investigated by electrochemical impedance Spectroscopy (EIS). The results indicated that all the Mg alloy-rich primers could provide cathodic protection for AA 2024 T3 substrates. However, the Mg alloys as pigments in metal-rich primers seemed to exhibit the different anti-corrosion protection performances, such as the barrier properties, due to the different properties of these pigments. In these investigations, multiple samples of each system were studied and statistical methods were used in analyzing the EIS data. From these results, the recommendation for improved EIS data analysis was made. CPVC studies were carried out on the Mg alloy-rich primers by using three Mg alloy pigments, AM60, AZ91B and LNR91. A modified model for predicting CPVC is proposed, and the results showed much better agreement between the CPVC values obtained from the experimental and mathematical methods. Using the data from the AM60 alloy pigment system, an estimate of experimental coarseness was done on a coating system, the first time such an estimate has been performed. By combining various surface analysis techniques, such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and confocal Raman microscopy, the oxidation products formed after exposure were identified. It was found that variation of Al content in Mg alloy could significantly affect the pH of the microenvironment in the primer films and result in the formation of various oxidation products.Air Force Office of Scientific Research (Grant No. 49620-02-1-0398)
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Xia, Lin. "Formation and function of chromate conversion coating on aircraft aluminum alloy probed by vibrational spectroscopy /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488196781732277.
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Mertens, Jeremy. "Atmospheric plasma treatment of aluminum alloy surfaces: Oxide growth and oxygen rich organic coating deposition." Doctoral thesis, Universite Libre de Bruxelles, 2019. https://dipot.ulb.ac.be/dspace/bitstream/2013/287803/3/these.pdf.
Повний текст джерелаАнотація:
L’objectif de cette thèse consiste en une étude fondamentale de différentes approches pour la modification de surfaces d’alliages d’aluminium. Elle s’inscrit dans le cadre du projet FLYCOAT, subventionné par la région Wallonne. Ce dernier avait pour objectif le développement d’alternatives au couplage classique d’un procédé d’anodisation utilisant des bains de Cr (VI) aux résines époxy pour la protection des alliages d’aluminium contre la corrosion. Dans un premier temps, la synthèse par plasma atmosphérique dans un réacteur de type décharge à barrière diélectrique (DBD) de films riches en groupements carboxyliques à partir de 8 précurseurs organiques est étudiée. Une attention particulière est portée à la compréhension fondamentale des mécanismes de polymérisation de ces précurseurs. L’influence significative de minimes variations de la structure chimique du précurseur est étudiée. Concrètement, nous démontrons l’impact de la présence et de la position de doubles liaisons ou encore le ratio C/O dans le monomère injecté sur le mécanisme de synthèse des couches déposées. Pour ce faire, une méthodologie combinant des analyses de la phase plasma et des films déposés est proposée. Les propriétés électriques de la DBD d’argon sont évaluées par oscilloscope avant et durant l’injection des différents précurseurs. La quantité d’énergie transférée de la décharge vers le précurseur est évaluée par spectroscopie d’émission optique et corrélée à sa structure. Une fragmentation réduite est mise en évidence par spectrométrie de masse pour les monomères contenant une double liaison. Ces analyses de la phase plasma sont alors corrélées avec les propriétés physiques et chimiques des films synthétisés. Les compositions chimiques de surface et de la matrice des couches minces sont étudiées par spectroscopie à photoélectrons X (XPS) et infrarouge. Le rôle essentiel de la présence et de la position de la double liaison dans la molécule injectée est démontré. Les vitesses de dépôt et la rugosité des films déposés par plasma atmosphérique avec l’injection des 8 précurseurs sont évaluées par profilométrie à stylet. Dans la seconde partie, le couplage de deux méthodes de plasma atmosphérique est proposé pour la synthèse de couches d’alumine aux propriétés adaptables. Le premier traitement consiste en un nombre varié de passages d’une torche plasma opérant dans un régime d’arc. L’effet du nombre de passages sur les propriétés physiques et chimiques du substrat est étudié par XPS, angle de contact, microscopie électronique à balayage et mesures de diffraction à rayons X. Une corrélation est suggérée entre le nombre de passages de la torche et les propriétés électrochimiques du substrat. L’influence de ce premier traitement sur les propriétés de la couche d’oxyde d’aluminium synthétisée par oxydation par plasma électrolytique est mise en évidence. Dans un troisième temps, le plasma pouvant être considéré comme un réservoir d’énergie, une étude de faisabilité est réalisée afin d’évaluer sa potentielle utilisation pour la réticulation d’une résine de type benzoxazine. L’efficacité du traitement par DBD atmosphérique d’argon ou hélium est comparée et discutée.Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Yin, Zhangzhang. "Development of an Environmentally Benign Anticorrosion Coating for Aluminum Alloy Using Green Pigments and Organofunctional Silanes." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1259076329.
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Gavelius, Marianne, and Karin Andersson. "Surface Treatment for Additive Manufactured Aluminum Alloys." Thesis, Linköpings universitet, Molekylär ytfysik och nanovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-169027.
Повний текст джерелаАнотація:
Manufacturing of aircraft parts is often complex and time-consuming, which has led to an increased interest in new manufacturing technologies in the Swedish industry such as additive manufacturing (AM). Additive manufacturing techniques could be a solution to meet the aircrafts’ demand since it contributes to an efficient manufacturing and allows a just-in-time production of complex metal parts in their final shape. However, the use of AM aluminum for aircraft applications is in a development phase and no surface treatment process exists. Thereby, it is of high interest to further investigate surface treatments for AM alloys. Currently at Saab AB, conventional aluminum alloys are generally anodized in tartaric sulphuric acid (TSA) to improve the corrosion resistance and adhesion properties of the metal. On the behalf of Saab AB, there is also an interest in establishing powder coating as a surface treatment. This master thesis’ purpose is to investigate the anodizing and adhesion properties for the two additive manufacturing alloys - AlSi10Mg and ScalmalloyⓇ, and compare it with the conventionally produced Al alloy 2024-T3. The anodization and the powder coating is examined by using following characterization techniques: profilometry, light microscopy, scanning electron microscopy and contact angle measurements. The results from the experimental part indicated successful anodizations for all the alloys and good adhesion properties for powder coating. This research is a first step in contributing to a better understanding of the anodic coating and adhesion properties for the AM samples ScalmalloyⓇ and AlSi10Mg
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Gordon, Matthew. "A Nacreous Self-Assembled Nanolaminate for Corrosion Resistance on 2024-Al Alloy." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33548.
Повний текст джерелаАнотація:
Nanometer thick layers of clay and polymer were formed on mica, silicon, and aluminum 2024-T3 alloy using alternating solutions of positively and negatively charged polymer and clay, respectively. Atomic force microscopy was used to observe the morphology of the composite films on mica and silicon. It was found that solution concentrations of clay above 0.02 weight percent lead to the uncontrolled deposition of clay platelets on the substrateâ s surface. By using solution concentrations of clay above 0.02 weight percent and ultrasonic agitation together it is possible to deposit a uniform monolayer of clay platelets on a mica substrate in £ 20 seconds. Ultrasonic agitation also produced crude patterns of montmorillonite platelets.
Thin films of poly(diallydimethylammonium chloride) (PDDA) were made using concentrations ³ 2 weight percent of PDDA. It was found that the PDDA formed several unusual morphologies. Spherulites of PDDA were observed with AFM and the glass transition temperature of high molecular weight PDDA was measured using differential scanning calorimetry (DSC).
Circular regions of positive charge were discovered on silicon wafers provided by three different sources. These areas of charge have never been reported in literature, but can easily be detected by placing wafers into solutions containing negatively or positively charged solutions of clay or polymer, respectively. The exact nature of these charged regions is unknown, but it is hypothesized that impurities on silicon wafers create the circular regions of positive charge.
ISAM films made of a polyamide salt and a synthetic clay, Laponite RD®, demonstrated significant corrosion resistance on 2024-T3 Al alloys after 168 hours of salt spray testing. The ISAM films offered corrosion protection only if there was a significant layer of underlying surface oxide present, however. It was found that ISAM deposited films of polyarylic acid (PAA) and polyallylamine hydrochloride (PAH) may offer some corrosion resistance on 2024-T3 Al alloys, but these filmsâ corrosion resistance is severely hampered by the presence of Cl- in the PAH solution.
Funding from this project was gratefully received from the Materials Science and Engineering Department at Virginia Tech; Luna Innovations Inc; the American Chemical Society / Petroleum Research Fund #34412-G5 and the Environmental Protection Agency Contract #68-D-00-244.Master of Science
11
Wang, Xi. "Corrosion Protection of Aluminum Alloy 2024-T3 by Al-Rich Primer." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1557143060015145.
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Yoon, Yuhchae. "Formation and breakdown on chromate conversion coatings on Al-Zn-Mg-Cu 7x75 alloys." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1101754567.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xxi, 282 p.; also includes graphics (some col.). Includes bibliographical references (p. 262-282).
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Stimpfling, Thomas. "Modified layered double hydroxide (LDH) platelets as corrosion inhibitors reservoirs dispersed into coating for aluminun alloy 2024." Thesis, Clermont-Ferrand 2, 2011. http://www.theses.fr/2011CLF22169.
Повний текст джерелаАнотація:
L’alliage d’aluminium 2024 est très répandu dans l’industrie aéronautique et automobile. Le processus de corrosion peut entrainer des dommages irréversibles pouvant engendrer des issues fatales dans le domaine aéronautique. Ainsi plusieurs couches de revêtements sont déposées à la surface du métal à protéger pour prévenir le processus de corrosion. Depuis le début du 20ième siècle, le chrome hexavalent (CrVI) a été largement utilisé comme inhibiteur de corrosion dans les différentes couches du revêtement (prétraitement, primer et top-coat). La toxicité de ce composé envers l’homme et l’environnement a entrainé son interdiction et donc son remplacement comme agent de protection. Le confinement d’agent anticorrosif dans des nano-conteneurs a ainsi été reporté puisqu’un effet auto-réparant, en relargant sur demande, peut-être apporté : l’inhibiteur de corrosion agit quand le dommage apparait. Cette étude est focalisée sur l’utilisation de matériaux de type Hydroxydes Doubles Lamellaires (HDL) comme réservoir d’inhibiteurs de corrosion en raison leur propriété d’échange. Dans ce travail, plusieurs molécules ont été étudiées comme potentiel inhibiteur de corrosion. Celles-ci ont été tout d’abord caractérisées par DC-polarisation afin de déterminer la nature de leur comportement inhibiteur (anodique, cathodique ou les deux). Ensuite, ces agents anticorrosifs ont été intercalés dans des matrices HDL et leur capacité de relargage ainsi que leur comportement face au processus de corrosion ont été étudiés. Les particules HDL ainsi obtenues ont été dispersées dans la formulation d’un revêtement primaire et déposé directement sur l’alliage aluminium 2024. La résistance à la corrosion a été suivie par spectroscopie d’impédance complexe. Les propriétés d’auto-protection de notre revêtement (relargage d’agent anticorrosive encas de dommage) et leur propriété barrière, apportée par la morphologie lamellaire des nano-conteneurs, entrainant une diminution de la perméabilité aux espèces agressives (ex. eau, O2, électrolyte) responsable de l’apparition de cloques sur les revêtements, ont ainsi été caractériséesAluminum alloy 2024 is widely used in aircraft and automotive industry. Corrosion processes can provide irreversible damage on the metal substrate which could have a tragic issue in the aircraft domain. Thus, several coating layers have been applied on the metal substrate to prevent corrosion process. Since the beginning of the 20th century, hexavalent chromate compounds have been extensively used as corrosion inhibitor agents for paint, primer and conversion coating. The toxicity for human health and environment has led to replace such compounds. The literature has reported different possibilities to replace such unfriendly compounds. Moreover, the entrapment of corrosion inhibitors in nanocontainer provides a self-healing effect by releasing, on demand, the active species when damage occurs. This study focuses on Layered Double Hydroxide (LDH) material as reservoir due to its exchange properties. This study has characterized several potential corrosion inhibitor molecules by DC-Polarization to determine the nature of the inhibitor compound (i.e. anodic, cathodic or both of them). Further, active anticorrosive species have been intercalated into LDH framework. Then, the release of inhibitor agents and their subsequent behaviour toward corrosion inhibition have been evaluated. Modified LDH materials have been further dispersed in the primer coating formulation and applied on aluminum alloys 2024 substrate. Corrosion inhibition has been followed by electrochemical impedance spectroscopy experiments on scratched and unscratched panel which have permitted to evaluate the self-healing property of these modified LDH materials when damage occurs and the barrier property provided by the lamellar morphology of the inorganic reservoir that is found to decrease the permeation by enhancing the tortuosity of the coating layer towards aggressive species (i.e. water, O2, electrolyte) responsible of the blistering phenomenon
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Sharma, Anurag. "Effects of Advanced Surface Treatments on Microstructure, Residual Stress and Corrosion-Fatigue Behavior of Aluminum Alloy 7075-T6." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin162765884039947.
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Borisova, Dimitriya. "Feedback active coatings based on mesoporous silica containers." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6350/.
Повний текст джерелаАнотація:
Metalle werden oft während ihrer Anwendung korrosiven Bedingungen ausgesetzt, was ihre Alterungsbeständigkeit reduziert. Deswegen werden korrosionsanfällige Metalle, wie Aluminiumlegierungen mit Schutzbeschichtungen versehen, um den Korrosionsprozess aktiv oder passiv zu verhindern. Die klassischen Schutzbeschichtungen funktionieren als physikalische Barriere zwischen Metall und korrosiver Umgebung und bieten einen passiven Korrosionsschutz nur, wenn sie unbeschädigt sind. Im Gegensatz dazu kann die Korrosion auch im Fall einer Beschädigung mittels aktiver Schutzbeschichtungen gehemmt werden. Chromathaltige Beschichtungen bieten heutzutage den besten aktiven Korrosionsschutz für Aluminiumlegierungen. Aufgrund ihrer Giftigkeit wurden diese weltweit verboten und müssen durch neue umweltfreundliche Schutzbeschichtungen ersetzt werden. Ein potentieller Ersatz sind Schutzbeschichtungen mit integrierten Nano- und Mikrobehältern, die mit ungiftigem Inhibitor gefüllt sind. In dieser Arbeit werden die Entwicklung und Optimierung solcher aktiver Schutzbeschichtungen für die industriell wichtige Aluminiumlegierung AA2024-T3 dargestellt
Mesoporöse Silika-Behälter wurden mit dem ungiftigen Inhibitor (2-Mercaptobenzothiazol) beladen und dann in die Matrix anorganischer (SiOx/ZrOx) oder organischer (wasserbasiert) Schichten dispergiert. Zwei Sorten von Silika-Behältern mit unterschiedlichen Größen (d ≈ 80 and 700 nm) wurden verwendet. Diese haben eine große spezifische Oberfläche (≈ 1000 m² g-1), eine enge Porengrößenverteilung mit mittlerer Porenweite ≈ 3 nm und ein großes Porenvolumen (≈ 1 mL g-1). Dank dieser Eigenschaften können große Inhibitormengen im Behälterinneren adsorbiert und gehalten werden. Die Inhibitormoleküle werden bei korrosionsbedingter Erhöhung des pH-Wertes gelöst und freigegeben.
Die Konzentration, Position und Größe der integrierten Behälter wurden variiert um die besten Bedingungen für einen optimalen Korrosionsschutz zu bestimmen. Es wurde festgestellt, dass eine gute Korrosionsschutzleistung durch einen Kompromiss zwischen ausreichender Inhibitormenge und guten Barriereeigenschaften hervorgerufen wird.
Diese Studie erweitert das Wissen über die wichtigsten Faktoren, die den Korrosionsschutz beeinflussen. Somit wurde die Entwicklung effizienter, aktiver Schutzbeschichtungen ermöglicht, die auf mit Inhibitor beladenen Behältern basieren.Metals are often used in environments that are conducive to corrosion, which leads to a reduction in their mechanical properties and durability. Coatings are applied to corrosion-prone metals such as aluminum alloys to inhibit the destructive surface process of corrosion in a passive or active way. Standard anticorrosive coatings function as a physical barrier between the material and the corrosive environment and provide passive protection only when intact. In contrast, active protection prevents or slows down corrosion even when the main barrier is damaged. The most effective industrially used active corrosion inhibition for aluminum alloys is provided by chromate conversion coatings. However, their toxicity and worldwide restriction provoke an urgent need for finding environmentally friendly corrosion preventing systems. A promising approach to replace the toxic chromate coatings is to embed particles containing nontoxic inhibitor in a passive coating matrix. This work presents the development and optimization of effective anticorrosive coatings for the industrially important aluminum alloy, AA2024-T3 using this approach. The protective coatings were prepared by dispersing mesoporous silica containers, loaded with the nontoxic corrosion inhibitor 2-mercaptobenzothiazole, in a passive sol-gel (SiOx/ZrOx) or organic water-based layer. Two types of porous silica containers with different sizes (d ≈ 80 and 700 nm, respectively) were investigated. The studied robust containers exhibit high surface area (≈ 1000 m² g-1), narrow pore size distribution (dpore ≈ 3 nm) and large pore volume (≈ 1 mL g-1) as determined by N2 sorption measurements. These properties favored the subsequent adsorption and storage of a relatively large amount of inhibitor as well as its release in response to pH changes induced by the corrosion process. The concentration, position and size of the embedded containers were varied to ascertain the optimum conditions for overall anticorrosion performance. Attaining high anticorrosion efficiency was found to require a compromise between delivering an optimal amount of corrosion inhibitor and preserving the coating barrier properties. This study broadens the knowledge about the main factors influencing the coating anticorrosion efficiency and assists the development of optimum active anticorrosive coatings doped with inhibitor loaded containers.
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ZIPPERIAN, DONALD CHARLES. "PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE ZINCATE IMMERSION PROCESS FOR ALUMINUM AND ALUMINUM ALLOYS." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184123.
Повний текст джерелаАнотація:
A detailed experimental study has been carried out to investigate the zincate immersion deposition process for 99.99%, 6061, and 356-T6 aluminum samples. In particular, the effect of iron and tartrate in the immersion bath, the aluminum surface preparation, and the relationship of the first immersion step to the second immersion step were investigated by chemical, electrochemical (polarization and rest potentials), and surface analytical scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) techniques. Eh-pH diagrams were constructed to determine the most stable zinc, iron, and aluminum species in solution. These diagrams predict that ferrous and ferric ions, as well as aluminum should form stable complexes with tartrate at the typical immersion deposition conditions (Eh -0.9 to -1.0 and pH 14 to 15). Experimentally, tartrate was found to enhance the dissolution rate of aluminum in highly caustic solutions. The addition of ferric chloride to the immersion bath produced coatings that were more crystalline, and also decreased the amount of hydrogen gas evolved in the second immersion step. The deposition of zinc and iron during the second immersion step was considerably less than that during the first immersion step. The second immersion coating became more adherent as the initial surface roughness decreased, and as grain size was increased the second immersion coating became thicker. For increasing grain size the micrographs for the first and second immersion coatings showed that the coatings became more localized. The second immersion coating thickness and morphology were also dependent upon several first immersion variables, such as bath temperature, immersion time and bath composition. Increased dissolution rates of aluminum in the first immersion produced thinner coatings with a finer crystallite growth. Increased bath temperature and increased first immersion time enhanced the dissolution rate of aluminum. The zinc coating slowed the dissolution rate of aluminum. When zinc was absent from the first immersion bath, the aluminum dissolution was much faster and resulted in thinner coatings upon subsequent second immersion. The molar ratio of zinc deposited to aluminum dissolved was a constant value of 1.1 for both first and second immersions; the molar ratio was also constant for the different aluminum substrates examined in this investigation.
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Even, Anaïs. "Compréhension des mécanismes d'inhibition de la corrosion dans le cadre de revêtements hybrides pour pièces aéronautiques." Thesis, Lorient, 2019. http://www.theses.fr/2019LORIS534.
Повний текст джерелаАнотація:
La lutte contre la corrosion dans l'industrie aéronautique est un défi permanent. Pour y répondre, le système actuel fait appel aux chromates qui présentent des qualités anticorrosives. Ces composés sont cependant classés cancérigènes, mutagènes, reprotoxiques. Un revêtement hybride sol-gel/polymère non toxique a été développé pour proposer une alternative au système de référence. Il présente des performances de protection contre la corrosion de l’alliage d’aluminium 2024-T3. Ce revêtement est innovant par son application par pulvérisation et sa polymérisation sous irradiation UV. Ce système est complexe et la compréhension des mécanismes mis en jeu lors de l’inhibition de la corrosion a fait l’objet de ce travail de thèse. Tout d'abord, les travaux menés ont permis de mettre en évidence la protection passive du revêtement et de relier ses performances à la structuration du film jusqu’à l’échelle nanométrique. Ensuite, en cas d’endommagement du revêtement, la protection active du revêtement a été étudiée. Lors de la sollicitation du revêtement, la réponse active du système inhibiteur de corrosion a été caractérisée par une exposition en milieu naturel et complétée par des essais accélérés de corrosion cyclique. Ce travail de recherche a montré que l’action d’un inhibiteur de corrosion est étroitement dépendante de la matrice dans laquelle il est intégré. La matrice du revêtement étudié est fermée et dense, conférant un effet barrière, mais réduisant la mobilité des espèces actives lorsque le substrat à protéger est mis à nu. Ces tests révèlent que le revêtement hybride apporte uneprotection supérieure par comparaison à une peinture commerciale non chromatéThe struggle against corrosion in the aeronautical industry is an ongoing challenge. To meet these requirements, the current system uses chromates with anticorrosive properties. However, these compounds are classified as carcinogenic, mutagenic, reprotoxic. A non-toxic sol-gel/polymer hybrid coating has been developed to provide an alternative to the reference system. This coating is innovative in its application by spray and a one-step UV-curing polymerization. This system is complex and the understanding of the mechanisms involved in corrosion inhibition has been the subject of this thesis work. First, work conducted has allowed to highlight the passive protection of the coating and link its performance to the film structuration down to the nanoscale. Then, in case of damage to the coating, the active protection of the coating was studied. During solicitation of the coating, the active response of the corrosion inhibitor system was characterized by exposure to natural environment, supplemented by accelerated cyclic corrosion tests. This research work has shown that the action of a corrosion inhibitor is closely dependent on the matrix in which it is integrated. The coating matrix is closed and dense, providing a barrier effect, but reducing the mobility of active species when the substrate to be protected is exposed. These tests have shown that the hybrid coating provides superior protection in comparison with a non-chromatedcommercial paint
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Abdul-Mahdi, F. S. "Tribological characteristics of coatings on aluminium and its alloys." Thesis, Brunel University, 1987. http://bura.brunel.ac.uk/handle/2438/5016.
Повний текст джерелаАнотація:
Hard anodising on aluminium and its alloys has been widely practised for many years in order to improve the resistance of the otherwise poor wear characteristics of aluminium. In recent years there has been an increasing interest in other treatments and coatings, on both aluminium and other base metals. The aim of this investigation is to explain the tribological performance and wear mechanism(s) of an uncoated aluminium alloy, four anodic coated alloys, and also an electroless nickel alloy. All of the coatings are produced on three different aluminium alloys. The thickness of the anodic films is 30-35 micron, as this thickness falls within the range commonly used by industry. In an endeavour to explain the role of coating thickness on wear life, electroless nickel alloy has been produced in a range of thicknesses of 10, 20 and 30 micron. To evaluate abrasive and adhesive wear, the samples were rubbed against a single point diamond and steel ball, respectively, in a reciprocating movement at room temperature and 65-75% relative humidity, under a wide range of load and sliding distance. Some tests continued to run until a breakdown of the coatings occurred, whilst other tests were interrupted at intermediate stages. This enabled the initiation and propagation of failure mechanisms to be studied. Abrasive wear was performed under dry conditions, whereas, adhesive wear was evaluated under both dry and lubricated conditions. Wear of these coatings was proportional to the applied load and sliding distance, but there was no direct relationship between wear and hardness. The tribological performance of these coatings appears to be dictated by a) the composition of the substrate, b) the chemical and physical nature of the coatings and c) the test conditions. Under boundary lubricated conditions there was a considerable increase in the wear life of the coatings. A three dimensional surface texture is superior to a machined surface, in controlling contact conditions. There is an approximate linear relationship between coating thickness and wear life for electroless nickel alloys. These coatings predominantly fail by adhesion, plastic deformation and brittle fracture. A microscopic model for fracture of brittle materials, under both static and dynamic conditions for abrasive and adhesive wear correlates very well with the behaviour of these coatings. Analytical interpretation of adhesive wear was made by separately calculating the coefficient of wear "K" of the counterbodies. This information enables an improved understanding of the wear test itself to be added to the model of the wear mechanisms involved.
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Etheridge, Andrea Mary. "Conversion coatings on aluminium alloys." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307051.
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Wang, Yingying. "Electrochemical behavior of cold sprayed coatings dedicated to corrosion protection applications : Role of microstructure." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0026.
Повний текст джерелаАнотація:
Le Cold spray est une technique de réalisation de dépôts épais par projection à haute vitesse de particules. Pour cette technologie, la température du gaz vecteur reste inférieure au point de fusion de poudres projetées. Dans ce cas, les mécanismes d’adhésion sont liés aux hautes déformations plastiques que subissent les particules lors de leur impact avec le substrat. Parmi la grande variété de poudres disponibles, trois compositions ont été retenues pour ce travail. Elles autorisent l’élaboration (i) d’alliage d’aluminium, (ii) d’acier inoxydable et (iii) de magnésium. L’ajout de particules de SiC (en fonction de leur quantité ou taille) aux poudres d’aluminium a également permis de modifier les propriétés mécaniques (telle que la dureté) des couches produites. En formant des couches denses et très peu poreuses, les revêtements cold spray présentent tous les atouts des revêtements anti-corrosion. Ce travail de thèse s’est attaché à comprendre les relations existantes entre les paramètres de projection de poudres (température et pression du gaz vecteur, concentration et tailles des particules de SiC) et la qualité du revêtement obtenu, de définir les interfaces substrat / revêtement en fonction de leur composition chimique et leurs influences sur les propriétés de protection vis-à-vis de la corrosion du substrat. D’un point de vu microstructural, les résultats obtenus montrent que l’augmentation de température du gaz améliore la densité des revêtements. En diminuant le nombre de défauts mais également en optimisant la qualité de l’interface substrat/revêtement, la résistance à la corrosion se trouve également améliorée. Sur la base des différences de potentiel entre le revêtement et le substrat, il est possible de classer la nature des couches selon (i) les revêtements sacrificiels et (ii) les revêtements cathodiques. Quel que soit leur nature, les revêtements obtenus par cold spray présentent tous de bonnes propriétés barrières. Toute fois le mode de dégradation des revêtements sacrificielles a pu être assimilé à de la corrosion intergranulaire en lien avec la morphologie du dépôt mais également la distribution et la taille de particule SiC (cas particulier du revêtement d’aluminium). Si les essais de corrosion longue durée ne permettent pas d’amorcer la corrosion du substrat après dissolution du revêtement (pour les couches sacrifielles), des essais de corrosion galvanique autorisent une discrimination rapide de l’efficacité de la couche barrière. Ces tests électrochimiques sont également l’occasion de discuter des effets de la rupture d’un revêtement sur les cinétiques de corrosion des matériaux qu’ils protègent. L’ensemble des caractérisations métallurgiques ainsi que les tests électrochimiques menés sur les différents assemblages substrat/revêtements indiquent que la technique de cold spray est une méthode de choix pour la protection des matériaux de structures vis-à-vis de la corrosionCold spray is a relatively new coating technology in which coatings are produced by powders projected at high velocity. A significant feature of cold spray is that bonding is generated through severe plastic deformation at temperatures well below melting point of feedstock powders. In the present study, kinds of metallic coatings were produced by cold spray, including aluminum alloy coating, pure magnesium coating, magnesium alloy coating, stainless steel coating and SiC reinforced composite coatings. According to the manner in which the coating protects its substrate against corrosion, these cold sprayed coatings can be divided into two types, i.e. sacrificial anodic coating and noble barrier coating. The objective of this thesis is to verify the feasibility of producing both sacrificial anodic coating and noble barrier coating with high corrosion performance by cold spray, and meanwhile demonstrate the usefulness of electrochemical measurements for the characterization of corrosion protection properties of cold sprayed coatings. Besides material system, process parameters which influence corrosion performance of cold sprayed coatings were studied. Two factors, i.e. process gas temperature and process gas pressure were chosen. Results showed that higher process gas temperature leads to denser aluminum coating. Likely, higher process gas pressure improves denseness and corrosion resistance of stainless steel 316L coating. SiC reinforced aluminum based composite coatings were deposited on aluminum, stainless steel and magnesium substrate. Compared with aluminum coating, the addition of hard ceramic particle affects microstructure of coatings, and improves corrosion resistance by increasing denseness. Ceramic particle fraction and size affect coating microstructure in different ways and also influence corrosion behavior. In view of corrosion process, results indicate that corrosion protection of cold sprayed coating could be divided into two steps. In the first step, substrate is completely shielded by dense coating, no corrosion reaction occurs on substrate. In the second step, two types of coatings show totally different behavior. In the case of sacrificial anodic coating, substrate is under cathodic protection in galvanic couple; hence no corrosion (or weakened corrosion) happens on substrate. In contrast, when the coating is noble than substrate, the protection effect would be immediately interrupted once corrosive electrolyte penetrates through coating to interface. The overall results indicate that cold spray is a highly reliable alternative for production of coatings in anti-corrosion applications. Electrochemical measurements are useful tools for quality evaluation of corrosion behavior of cold sprayed coatings
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George, Faith Olajumoke. "Chromium-free conversion coating of aluminium-copper alloys." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/chromiumfree-conversion-coating-of-aluminiumcopper-alloys(5176c8af-02af-44a8-a47f-44b5a0c2585c).html.
Повний текст джерелаАнотація:
Aluminium alloys are frequently pre-treated by a conversion coating before application of an organic coating in order to improve the corrosion resistance and adhesive properties of the surface and the corrosion resistance provided by the system. Chromate-containing conversion coatings are commonly used for this purpose. However, legislation limits future use of hexavalent chromium compounds due to their toxic and carcinogenic nature. Therefore, alternative, so-called chromium-free conversion coatings are being developed that are more environmentally-compliant.The purpose of the present work has therefore been to contribute to a better understanding of how the aluminium substrate affects the formation and properties of conversion coatings for adhesive bonding. In particular, a chrome-free zirconium-based conversion treatment process has been investigated as a possible replacement for conventional chromate conversion treatment. The influence of the conversion time on the thickness of the formed layer on pure aluminium was investigated using complementary surface analytical techniques. The conversion time was varied between 30 and 600 seconds.In this study, the structure and composition of zirconium-based chromium-free conversion coatings on magnetron sputtered superpure aluminium and a range of aluminium-copper alloys were characterised as a function of immersion time in the aqueous conversion bath to understand the mechanism of coating formation and protection. However, the presence of copper significantly influences the coating development and ultimately the performance of the conversion coatings formed on binary copper-containing aluminium alloys.The morphology and composition of the coatings have been probed using transmission electron microscopy, Rutherford backscattering spectroscopy and glow discharge optical emission spectroscopy, with loss of substrate through growth of the conversion coating also quantified. A comparison of the RBS spectra obtained for the superpure aluminium specimens after different immersion times revealed that zirconium (Zr) and oxygen (O) peaks were wider for longer immersion times, indicating thickening of the coating with increased immersion times. Thus, increasing the immersion time resulted in an increase in coating thickness but little change in coating composition occurred as determined by the RBS RUMP simulations. Alloying decreases the coating thickness, as well as metal consumption. Here, aspects of the corrosion behaviour of superpure aluminium and aluminium-copper alloys were also considered using electronoptical, electrochemical and surface analytical probing. The influence that short and prolonged treatment times exert on the performances of such conversion coating is discussed. The conversion coating formed after 60 s and 180 s of immersion in the zirconium-based conversion coating bath provide good corrosion resistance which can be attributed to the high stability of the compounds that constitute the surface oxide layer, and good adhesion properties.
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Cai, Hong. "Microbiologically influenced corrosion and titanate conversion coatings on aluminum alloy 2024-T3 /." View online ; access limited to URI, 2006. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3225314.
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Berube, Gregoire. "Development of metastable aluminum alloy coatings and parts for automotive applications." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28328.
Повний текст джерелаАнотація:
In this study, a metastable Al-Fe-V-Si alloy powder was produced by rapid solidification using the gas atomization process. The alloy composition was chosen for its mechanical properties at elevated temperature for potential applications in internal combustion gasoline engines. The microstructural properties of the Al-Fe-V-Si powder were determined through transmission electron microscopy imaging and selected area electron diffraction indexing, energy dispersive spectroscopy, X-ray diffraction and differential scanning calorimetry. Three distinct microstructures were observed as well as two different phases, namely a Al13(Fe,V)3Si silicide phase and a metastable (Al,Si)x(Fe,V) micro-quasicrystalline icosahedral (MI) phase. The metastable MI phase was determined to be thermally stable up to 380°C, after which a phase transformation to silicide occurs. The Cold Gas Dynamic Spraying (CGDS) process was used to produce coatings of the alloy. This spray process was selected due to its relatively low operating temperature, thus preventing significant heating of the particles during spraying and as such allowing the original microstructure of the feedstock powder to be preserved within the coatings. Coatings were produced by CGDS using Helium and Nitrogen as propellant gases. The coatings microstructure was investigated using scanning electron microscopy and transmission electron microscopy analyses. The mechanical properties of the coatings were then evaluated through bond strength testing and microhardness testing.
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Akhtar, Anisa Shera. "Surface science studies of conversion coatings on 2024-T3 aluminum alloy." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1713.
Повний текст джерелаАнотація:
The research in this thesis aims to develop new mechanistic knowledge for coating processes at 2024-Al alloy surfaces, ultimately to aid the design of new protective coatings. Coatings formed by phosphating, chromating, and permanganating were characterized especially by scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy, and scanning electron microscopy . The objective was to learn about growth (nm level) as a function of time for different coating baths, as well as a function of lateral position across the different surface microstructural regions, specifically on the μm-sized Al-Cu-Mg and Al-Cu-Fe-Mn particles which are embedded in the alloy matrix . The research characterizes coating thickness, composition, and morphology.
The thesis emphasizes learning about the effect of different additives in zinc phosphating baths . It was found that the Ni²⁺ additive has two main roles : first, the rate of increase in local solution pH is limited by the slower kinetics of reactions involving Ni²⁺ compared to Zn²⁺, leading to thinner zinc phosphate (ZPO) coatings when Ni²⁺ is present. Second, most Ni²⁺ deposition occurs during the later stages of the coating process in the form of nickel phosphate and a Ni-Al oxide in the coating pores on the alloy surface, increasing the corrosion resistance. Aluminum fluoride precipitates first during the initial stages of the coating process, followed by aluminum phosphate, zinc oxide, and finally ZPO.
When Ni²⁺ is present in the coating solution at 2000 ppm, ZnO predominates in the coating above the A-Cu-Fe-Mn particle while ZPO dominates on the rest of the surface. The Mn²⁺ additive gives a more even coating distribution (compared with Ni²⁺) across the whole surface. The Mn²⁺ -containing ZPO coating is similar to the chromate coating in terms of evenness, while there is more coating deposition at the second-phase particles for permanganate coatings. The oxides on the Al-Cu-Fe-Mn and matrix regions are similar before coating, thereby confirming that a variety of observed differences in ZPO coating characteristics at these regions arise from the different electrochemical characteristics of the underlying metals. Upon exposure to a corrosive solution, the ZPO coating provides more protection to the second-phase particles compared to the matrix.
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Coward, M. I. E. "Vanadate - based conversion coatings for the aluminium alloy 2014A - T6." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/7591.
Повний текст джерелаАнотація:
The aluminium alloy 2014A-T6 is used as an aerospace alloy due to its strength and rigidity. The disadvantage of this alloy is that it is susceptible to galvanic corrosion, this occurs due to the fact that the main alloying element, copper, forms discreet precipitates principally of CuAl2 which are noble to the main aluminium matrix. One of the main ways in protecting the alloy from corrosion is by the application of a passive chromate conversion coating. Due to legislation, chromates are being outlawed, so replacements are being sought Investigations into sodium orthovanadate as an alternative conversion coa ing, showed that it provided a degree of protection against chloride ion attack from both salt spray testing and immersion in 3.5% sodium chloride. Tests were carried out to see if coating of the copper intermetallic could reduce the amount of galvanic attack the 2014A-T6 Al alloy was subjected to. Investigations were carried out in to the inhibition the copper surface by the use of sulphur-based compounds. The results showed that inhibition did not occur. However, further investigations into organic acids such as sebacic acid showed that when added to the sodium orthovanadate solution they promoted greater corrosion protection by reacting with the alkaline sodium orthovanadate solution to form sodium sebacate. The sodium sebacate was able to block cracks on the coating surface thereby inhibiting ingress of chloride ions to the surface of the 2014A-T6 Al alloy. This was proved by the use of scanning electron microscopy, which showed the presence of fine needle like features of precipitated sodium sebacate. X-ray photoelectron spectroscopy results showed that there was a high possibility that sodium sebacate was present on the surface due to the presence of both carbon and sodium which were not present when the alloy was treated from a solution containing just sodium orthovanadate. A variety of coatings were analysed using D. C. electrochemical polarisation, it was found that the sodium orthovanadate treatment, containing the sebacic acid, gave a considerable increase in the corrosion resistance in 3.5% NaCl compared to all other coatings except chromate. However, the sodium orthovanadate coating containing sebacic acid showed a reasonably close corrosion. resistance to the Alochrom 1200 chromate coating when subjected to salt spray corrosion tests. Simulated samples of 2014A-T6 Al alloy were produced by coupling laboratory produced CuAl2 and commercially produced aluminium. The results obtained using D. C. electrochemical polarisation gave similar trends to that obtained by a commercial sample of 2014A-T6 Al alloy showing that the sodium orthovanadate/sebacic acid coating solution was highly effective. This was backed up by the use of zero resistance ammetery which showed that the sodium orthovanadate/sebacic acid at 60 seconds at 60°C showed broadly comparable results with chromates up until 190 hours, when the coated couples were immersed in 3.5% NaCl at 25°C.
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Feng, Zuwei. "Formation of sol-gel coatings on aluminium alloys." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/formation-of-solgel-coatings-on-aluminium-alloys(7e6eed7e-959b-487d-bc3a-5950d584ca42).html.
Повний текст джерелаАнотація:
Organically modified sol-gel coatings have been investigated as potential replacements for chromate conversion coating of AA1050 and AA2024 aluminium alloys. The coatings were prepared by a combination of a completely hydrolysable precursor of tetra-n-propoxyzirconium (TPOZ), with a partially hydrolysable precursor of glycidoxypropyltrimethoxysilane (GPTMS). GPTMS contains organic functional groups, which are retained in the sol-gel coatings after the hydrolysis-condensation process. Different process parameters, e.g. GPTMS/TPOZ ratios, withdrawal speeds, solvent water concentrations, and curing temperatures were studied. Coatings produced using a low GPTMS/TPOZ ratio and a high withdrawal speed generated significant cracks due to the shrinkage of the coatings. It was found that increase of organic moieties reduced the shrinkage of the coatings and the tendency for crack formation. By controlling process parameters and ratios of organic and inorganic moieties, crack-free sol-gel coatings from 0.1 μm to 9 μm thick can be achieved. The sol-gel coatings formed are amorphous and contain organic epoxy-ether retained silicon oxide, silicon hydroxide, zirconium oxide, zirconium hydroxide, and zirconium acetate. The Si/Zr ratios of resultant sol-gel coatings are proportional to the initial GPTMS/TPOZ ratio. Cerium oxide nanoparticles were successfully incorporated into sol-gel coatings with a single layer and double layer sol-gel process. Through the dip coating process, crack-free sol-gel coatings, of varied thickness, were developed on different aluminium substrate, including electropolished superpure aluminium, magnetron sputtered aluminium with varied copper contents from 0 to 30 wt.%, and commercial AA1050 and 2024 aluminium alloys. Sol-gel coatings formed on commercial AA1050 and 2024 aluminium alloys revealed a significant passivation in 3.5 wt.% sodium chloride solution during anodic polarisation when the sol-gel coating is more than 1 µm thick and proper surface pretreatments of the alloys were used. Corrosion tests by immersion in 3.5 wt% sodium chloride solution and by salt spray in 5 wt.% sodium chloride solution revealed that sol-gel coatings successfully protected AA2024 aluminium alloy against the aggressive environment and have the potential to replace chromate containing coating systems.
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Hendrick, Michelle Renee. "The effects of combustion CVD-applied alumina coatings on the high temperature oxidation of a Ni-Cr alloy." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19635.
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Kottarath, Sandeep. "Processing & properties of clay-ICP/polyimide nanocomposite coatings on aluminum alloy." Cincinnati, Ohio University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1097454077.
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GUO, YANG. "A Study of Trivalent Chrome Process Coatings on Aluminum Alloy 2024-T3." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308166499.
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Sears, Joanne Marie. "An investigation of aluminium-magnesium-cerium alloy coatings for corrosion protection." Thesis, University of Salford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365974.
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Smit, Mascha. "Titanium-based no-rinse conversion coatings on aluminium alloys." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301402.
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Danilidis, Ioannis. "Manganese-based no-rinse conversion coatings for aluminium alloys." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299758.
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Boerstler, Joshua Trevitt. "Corrosion Degradation of Coated Aluminum Alloy Systems through Galvanic Interactions." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524185375873158.
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Xu, Nan Materials Science & Engineering Faculty of Science UNSW. "Corrosion behaviour of aluminised steel and conventional alloys in simulated aluminium smelting cell environments." Awarded by:University of New South Wales. School of Materials Science & Engineering, 2002. http://handle.unsw.edu.au/1959.4/18760.
Повний текст джерелаАнотація:
Aluminium smelting is a high temperature electrometallurgical process, which suffers considerable inefficiencies in power utilization and equipment maintenance. Aluminium smelting cell works in the extreme environments that contain extraordinarily aggressive gases, such as HF, CO and SO2. Mild steel used as a structural material in the aluminium industry, can be catastrophically corroded or oxidized in these conditions. This project was mainly concerned with extending the lifetime of metal structures installed immediately above the aluminium smelting cells. An aluminium-rich coating was developed on low carbon steel A06 using pack cementation technique. Yttria (Y2O3) was also used to improve the corrosion resistance of coating. Kinetics of the coating formation were studied. XRD, FESEM and FIB were employed to investigate the phase constitution and the surface morphology. Together with other potentially competitive materials, aluminium-rich coating was evaluated in simulated plant environments. Results from the long time (up to 2500h) isothermal oxidation of materials at high temperature (800??C) in air showed that the oxidation resistance of coated A06 is close to that of stainless steel 304 and even better than SS304 in cyclic oxidation tests. Coated A06 was also found to have the best sulfidation resistance among the materials tested in the gas mixture contains SO2 at 800??C. Related kinetics and mechanisms were also studied. The superior corrosion resistance of the coated A06 is attributed to the slow growing alpha-Al2O3 formed. Low temperature corrosion tests were undertaken in the gas mixtures containing air, H2O, HCl and SO2 at 400??C. Together with SS304 and 253MA, coated A06 showed excellent corrosion resistance in all the conditions. The ranking of the top three materials for corrosion resistance is: 253MA, coated A06 and SS304. It is believed that aluminised A06 is an ideal and economical replacement material in the severe corrosive aluminium smelting cell environment.
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Dufek, Eric J. "Interfacial investigations of corrosion and corrosion inhibition on the aluminum alloy AA2024-T3." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1445041831&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Dong, Xuecheng. "Mechanism of Passivation and Inhibition of Trivalent Chromium Process Coating on Aluminum Alloys." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1335904469.
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Guo, Xiaolei. "Corrosion inhibition of aluminum alloy 2024-T3 based on smart coatings, hybrid corrosion inhibitors, and organic conversion coatings." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461188604.
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Reddy, Chandra M. "Improved corrosion protection of aluminum alloys by low temperature plasma interface engineering /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924918.
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Lee, David Tsu-Long. "Behaviour of corrosion-protection coatings in light alloys." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:bfbcec97-5f42-4eb3-aaec-ba5443e953ba.
Повний текст джерелаАнотація:
Anionic chromate (VI) compounds are inhibitive pigments and have been effectively incorporated into organic coatings to protect metal surfaces from aggressive ions, but their risk as a human carcinogen and being harmful to the environment has led to the search of suitable alternatives. Aluminium alloy, AA2024-T3, is the substrate metal alloy used in the experiments and can be found in aircraft fuselage structures due to their high strength-to-weight ratio. However, the presence of intermetallic particles increases susceptibility to localised corrosion. To investigate the protection mechanisms of primers on light alloys, many different factors must be taken into account; from aluminium alloy corrosion processes, the effects of intermetallic additions to coating chemistry, morphology and inhibitive pigments. The chemical environment in which the samples are tested in will also affect the corrosion mechanisms of the alloy as well as the performance of the coatings and release of pigments. It will be important to consider which factors are operating under particular conditions so that experimental results can then be best interpreted. As part of this project, potentiodynamic polarisation, electrochemical impedance spectroscopy and electrochemical noise analysis have been used to investigate the protective mechanisms in which chromate-based paints protect against corrosion and UV-Visible spectroscopy, scanning acoustic microscopy and optical microscopy have been used to investigate pigment release mechanism to identify what characteristics are important when developing new primers.
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Yue, Jingyi. "Corrosion Behaviors of Coated Aluminum Alloys in Simulated Corrosive Environment." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1485.
Повний текст джерелаАнотація:
This study investigated the corrosion of an aluminum alloy with and without coatings under simulated corrosive environments. Coatings were selected and applied from commercial materials and techniques, consisting of microceramic, epoxy primer, and topcoat. The experiments for coated specimens were carried out under various corrosive conditions, specifically, hydrodynamic flow, immersion in salt water and DI water, varying temperatures, and simulated sun light. The hydrodynamic conditions were simulated using a rotating cylinder electrode (RCE) with rotational speeds of 200, 400, 600, 800, and 1000 rpm. The immersion in saltwater and sunlight illumination tests were applied for 8 hours, and the simulated exterior temperature variation were cycled for 7 days. Polarization techniques were used to study the corrosion mechanism and calculate the corrosion rate of coated specimens under simulated salt water. Microstructure of coated specimens were identified by using atomic force microscopy (AFM) and optical microscope (OM) analysis. Results indicated that corrosions in the simulated salt water were generally more serious than those in the distilled water. This was especially true for bare aluminum alloys, that its corrosion rates in the salt water exhibited two orders of magnitude higher than those in the DI water. The combination of an environmentally friendly electrodeposited ceramic coating with a primer and topcoat, which results in a chromium-free coating, exhibited a higher polarization resistance and a lower corrosion rate than the traditional chromate conversion coating combination. In addition, for all coated Al alloys, the corrosion rate increased with increasing rotation speed. For immersion portion, immersion in salt water accelerated the pitting corrosion process and increased the corrosion rate of the aluminum alloy five times higher as compared to the samples without immersion. For the varying temperature portion, the rates of corrosion nearly doubled for bare and ceramic coated Al alloy, under varying temperature conditions for 7 days. Besides, addition of ionic liquid inhibitors, such as BMIMBR and BEIMCl, exhibited great improvement of corrosion resistances of aluminum alloy in the salt water. The corrosion rates of aluminum in the presence of inhibitors were almost one order of magnitude lower than that in the absence of inhibitors.
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Priest, Matthew. "Synthesis of reactive element-modified aluminide coatings on single-crystal Ni-based superalloys by a pack cementation process a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=26&did=1760523421&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1254926883&clientId=28564.
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Grilli, Rossana. "Conversion coatings for aluminium alloys : a surface investigation for corrosion mechanisms." Thesis, University of Surrey, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520579.
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Rajamani, Deepika. "Processing and Properties of Environmentally-Friendly Corrosion Resistant Hybrid Nanocomposite Coatings for Aluminum Alloy AA2024." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1138811300.
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ASHIRGADE, AKSHAY A. "ENVIRONMENTALLY-COMPLIANT NOVOLAC SUPERPRIMERS FOR CORROSION PROTECTION OF ALUMINUM ALLOYS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1153245386.
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Teixeira, Dilton Gonçalves [UNESP]. "Estudos da preparação de superfície da liga AA6063T5 e do desenvolvimento de revestimentos híbridos orgânico-inorgânicos a base de siloxano-PMMA para aplicação anticorrosiva." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/102551.
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Este trabalho está basicamente dividido em duas partes. A primeira está relacionada à limpeza da superfície da liga de alumínio AA6063T5 e sua influência na proteção contra a corrosão. A segunda parte se refere à preparação de revestimentos híbridos orgânicoinorgânico pelo processo sol-gel e deposição sobre a superfície da liga de alumínio por dipcoating. Três amostras de liga AA6063T5 foram investigadas: como recebida, debastada e polida mecanicamente e tratada quimicamente. O tratamento mecânico foi realizado utilizando lixas SiC de granulometria 320 a 4000 e o químico foi realizado utilizando uma solução aquosa contendo uma mistura de hidróxido, sulfato e cloreto de sódio. Todas as amostras foram caracterizadas fisicamente por difratometria de raios X (XRD), medidas de dureza, microscopia eletrônica de varredura (SEM) e microscopia óptica (MO), e por medidas de potencial de circuito aberto (OCP) e espectroscopia de impedância eletroquímica (EIS) em solução 3,5% NaCl. As imagens SEM mostraram que a presença de partícula intermetálicas na superfície da liga diminui após o tratamento químico comparado ao tratamento mecânico. Os resultados de EIS mostraram que o tratamento químico oferece maior resistência à corrosão do que as submetidas aos outros tratamentos, porque o ataque alcalino utilizado dissolveu a maioria dos precipitados contendo Fe ou Cu, elementos responsáveis por sítios catódicos. A lavagem com HNO3 pela qual passou a amostra tratada quimicamente provavelmente reforçou a camada de óxido, tornando a superfície da liga mais resistente ao ataque por cloreto. Os revestimentos híbridos foram somente depositados na liga que recebeu tratamento químico. Esses filmes híbridos foram preparados com tetraetoxi-silano (TEOS) e 3-metacriloxipropril trimetoxi silano (MPTS), pela hidrólise e policondensação em meio ácido seguido por...
This work is basically divided in two parts: the first one is related to the surface treatment of AA6063T5 aluminum alloy and its influence on the protection against corrosion. The second concerns to the preparation of organic-inorganic hybrid coatings by the sol-gel process that were deposited on the aluminum alloys by dip-coating. Three samples of AA6063T5 aluminum alloys were investigated, the as-received one, after mechanical and chemical treatment, respectively. The mechanical treatment was realized using SiC paper grades 320 to 4000 and the chemical one was done by an aqueous solution containing a mixture of sodium hydroxide, chloride and sulfate. All samples were physically characterized by X-ray diffractometry (XRD), hardness measurements, scanning electron microscopy (SEM) and optical microscopy (OM), and electrochemically by open circuit measurements (OCP) and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The SEM images depicted that the presence of intermetallic particles on the alloy surface decreased after the chemical treatment compared to the mechanical one. The EIS results showed that the sample chemically treated possesses a higher corrosion resistance than those obtained using other procedures. EIS results showed that the chemically treated sample presented higher corrosion resistance than the ones submitted to other procedures. The alkaline treatment dissolves the great part of precipitates containing iron or copper, which are responsible by the cathodic sites formation. The washing of the sample with nitric acid solution after the alkaline treatment removes impurities from the surface and can give to the oxide layer higher resistance against the action of the chloride ion. The hybrid coatings were only deposited on the alloy that received the chemical treatment. Hybrid films containing tetraethoxysilane (TEOS) and 3-methacryloxypropyltrimetho... (Complete abstract click electronic access below)
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Qi, Jiantao. "Trivalent chromium conversion coatings on Al and Al-Cu alloys." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/trivalent-chromium-conversion-coatings-on-al-and-alcu-alloys(138b7db5-0524-4bcc-a358-3d6bbc0d36d5).html.
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Trivalent chromium conversion coatings formed on Al and Al-Cu alloys has been investigated using high-resolution, analytical electron microscopy, atomic force microscopy, ion beam analysis, glow discharge optical emission spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, potentiodynamic polarization and electrochemical noise analysis. These coatings on the electropolished Al and sputtering-deposed Al consist of a chromium- and zirconium-rich outer layer and a thinner, aluminium-rich inner layer. Zirconium and chromium are presented in chemical states consistent with ZrO2, Cr(OH)3, Cr2(SO4)3, CrF3 and CrO3 or CrO42-. However, negligible amounts of hexavalent chromium species occurred in both coatings formed in de-aerated solution. On AA2024-T351 alloys, the coating above the second phase particles was thicker than that on the matrix due to the increased localized alkalinity. Moreover, the localized corrosion and copper enrichment of the matrix occurred at the coating base. The presence of copper resulted in a thinner coating at the matrix compared with superpure aluminium. An Fe(III)-containing D30 desmutter can effectively remove the protruded particles generated by alkaline etching. Moreover, a thinner oxide film on the D30-treated surface was evidenced to promote the coating initiation on the matrix. Further, the coating comprised the concentrated zirconium oxyfluorides and decreased contents of aluminium and copper. Coated alloys displayed a significantly enhanced corrosion protection, especially the cathoidc inhibition. In terms of coating post-treatments, the water immersion (40 ºC, pH 5) soon after conversion treatment revealed a simple but effective process to improve the fluoride enrichment in coatings and to enhance corrosion protection of freshly-developed coatings. Increasing concentration of solid-solution copper in sputtering-deposited alloys, in a range of 2, 24, 40 and 64 at.%Cu, significantly promotes the coating growth kinetics and an evident and a thicker corrosion layer by substrate dissolution was observed on Al-40 at.%Cu alloys. In addition, the relationship of copper-rich deposits with Cr(VI) transformation was demonstrated by Raman spectroscopy.
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SIQUEIRA, GONÇALO. "Caracterização microestrutural, mecânica e tratamento térmico da liga AA-6082 obtida pelo processo de conformação por spray." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10151.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Othman, Intan. "Electrodeposition of nickel coatings on aluminium alloy 7075 through a modified single zincating process." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/397142/.
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Electrodeposition on aluminium alloy substrates often is often difficult in producing a coating with good adhesion when compared to other metals. This is due to the rapid formation of oxide layers on the substrate’s surface when exposed to air and water, preventing metallic bonds from forming between the nickel coating and the aluminium alloy substrate which in turn resulting in poor adhesion. Adhesion of the coating on the substrate influences the quality of the coating. To overcome this problem, a series of critical surface pre-treatment procedures are required for a successful electrodeposition process with a strong coating adhesion. The pre-treatment process consists of mechanical grinding and polishing, alkaline and acidic cleaning, zincating and activation process. This study focuses on the zincating process to obtain a strong adherence coating on the substrate. An aim of this study was to replace the complex double zincating process. To this end, modification has been made to a conventional single zincating process, as the process results in a non-homogenous deposition of zinc particles on the substrate which leads to a poor adhesion of the coating. The modified process, for which the duration of the single zincating process was extended from 1 to 20 minutes, was based on the electrochemistry measurements of aluminium alloy 7075 substrate in the zincatingsolution. For comparison, nickel coatings prepared using a double zincating process at 60/10, 60/20, 60/30, 60/40 and 60/50 seconds were also produced in this study. By replacing the double zincating with a modified single zincating process, two pre- treatment steps of double zincating process will be eliminated. Thus, the waste disposal problem in terms of the chemical used in the zincating solution is reduced. In addition, copper activation was applied before the single zincating process in order to overcome the high dissolution of the substrate in the zincating solution. The surface pre-treated samples were characterized after alkaline cleaning, acid cleaning, zincating process and copper activation at various immersion durations by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and atomic force microscopy (AFM). The modified single zincated samples were found to contain larger zinc particles, as compared to the conventional single and double zincated samples. The modified single zincating process also showed an increasing trend in the nucleation density and size of zinc particles with time. A gradual decrease in the surface roughness values with the extension of the modified single zincating duration was also observed. Then, the influence of multiple zincating processes (conventional and modified single zincating with and without copper activation, and double zincating) at various durations on the coating adhesion was investigated using scratch adhesion test. Scratch failure modes were analysed using acoustic emission signals, frictional force, and microscopy observation. The conventional single zincating and double zincating processes resulted in poor adhesion of the nickel coatings to the substrate, as both the cohesive and adhesion failures occurred during the scratch test. The adhesion of the coating to the substrate was improved by extending the single zincating duration from 1 to 5, 10, 15 and 20 minutes, with only cohesive failure found for the samples. This result was supported by the number of acoustic emission activity (NAE) events recorded during the test, which showed the highest NAE at about 130 for the sample produced from the conventional single zincating process. An increase in the zincating duration to 5 minutes resulted in a drastic reduction of the NAE to 30. The similar adhesion behaviour was also observed on modified single zincated samples with copper activation. The corrosion tests were carried out by immersing the coatings in a 3.5 wt. % NaCl solution at room temperature. It was found that a modified single zincating process at a longer duration provided a significant enhancement of corrosion resistance as compared to the conventional single zincating process, due to the increase in corrosion potential and decrease in corrosion current density of the conventional single zincated sample. These much improved performance of coating adhesion and corrosion resistance maybe explained by homogenous distribution of zinc particles and good coverage of the zinc particles on the aluminium alloy substrate.
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Shabani-Nooshabadi, M., and Y. Jafari. "Electropolymerized Coatings of Poly (o-anisidine) and Poly (o-anisidine)-TiO2 Nanocompsite on Aluminum Alloy 3004 by using the Galvanostatic Method and Their Corrosion Protection Performance." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34811.
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Poly (o-anisidine) (POA) and also poly (o-anisidine)-TiO2 (POA-TiO2) nanocomposite coatings on aluminum
alloy 3004 (AA3004) have been investigated by using the galvanostatic method. The electrosynthesized
coatings were characterized by FT-IR, SEM- EDX, SEM and AFM. The corrosion protection performances
of POA and also POA-TiO2 nanocomposite coatings were investigated in 3.5% NaCl solution by using
the potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). The
corrosion rate of nanocomposite coatings was found ∼900 times lower than bare AA3004. The results of
this study clearly ascertain that the POA-TiO2 nanocomposite has outstanding potential to protect the
AA3004 against corrosion.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34811
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Raps, Dominik. "Development of a self-healing corrosion protection coating system for high strength aluminium alloys /." Düsseldorf : VDI-Verl, 2008. http://d-nb.info/990760103/04.
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