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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.
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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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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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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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Petersen, Amanda de Moura. "Comportamento inibidor da corrosão de antocianinas na liga de alumínio 2024-T3." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/153271.
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A eficiência de antocianinas como inibidores de corrosão da liga de alumínio 2024-T3 foi avaliada através de medidas eletroquímicas como a espectroscopia de impedância eletroquímica e polarizações anódica e catódica. Soluções de NaCl 0,025 mol.L-1 contendo diferentes concentrações (800, 1000, 2000, 3000, 5000 e 7200 ppm) de antocianinas extraídas da uva foram preparadas para analisar o efeito da presença destas substâncias quando em contato com a liga de alumínio 2024-T3. Medidas de espectroscopia de impedância eletroquímica apresentaram uma diminuição sobre a dispersão dos pontos nas regiões de baixas frequências com o acréscimo do tempo de contato das antocianinas com a superfície da liga de alumínio 2024-T3 de 1 hora para 3 dias de imersão. Além disso, o comportamento indutivo nestas regiões decresceu após 3 dias de imersão com uma elevação considerável da resistência à polarização e da eficiência de inibição em 1000 ppm de antocianinas. Sob polarizações anódica e catódica, também foi verificado um melhoramento generalizado das propriedades anticorrosivas como potencial de corrosão, corrente de corrosão e eficiência de proteção contra a corrosão, para a concentração de 1000 ppm de antocianinas. Análises de microscopia eletrônica de varredura, microscopia de força atômica e espectroscopia por dispersão de energia, confirmam a adsorção de antocianinas na superfície da liga, assim como medidas de absorbância após 3 dias de imersão.The efficiency of anthocyanins as corrosion inhibitor of the 2024-T3 aluminum alloy was evaluated by electrochemical measurements such as electrochemical impedance spectroscopy and anodic and cathodic polarizations. NaCl solutions 0.025 mol.L-1 containing different concentrations (800, 1000, 2000, 3000, 5000 and 7200 ppm) of anthocyanins extracted from grape were prepared to examine the effect of the presence of these substances when in contact with the 2024-T3 aluminum alloy. Electrochemical impedance spectroscopy measurements showed a decrease on the dispersion of points in the lower frequency regions with an increase of contact time of anthocyanins with the surface of the 2024-T3 aluminum alloy from 1 hour to 3 days of immersion. In addition, the inductive behavior in these regions decreased after 3 days of immersion with a considerable increase of the polarization resistance and inhibition efficiency of 1000 ppm of anthocyanins. Under cathodic and anodic polarizations, it was noted a general improvement in the anticorrosive properties such as corrosion potential, corrosion current and efficiency of protection against corrosion for the concentration of 1000 ppm of anthocyanins. Analyses of scanning electron microscopy, atomic force microscopy and energy dispersive spectroscopy confirm anthocyanins adsorption on to the surface alloy, as well as absorbance measurements in a spectrophotometer after 3 days of immersion.
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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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Tamborim, Takeuchi Silvia Margonei Mesquita. "Revestimentos anticorrosivos à base de silanos sobre a liga de alumínio 2024-T3." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16169.
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Revestimentos de silanos foram depositados sobre a liga de alumínio 2024 - T3 a fim de avaliar a sua utilização como revestimento protetor à corrosão. O capítulo I trata sobre o estudo do comportamento corrosivo de tratamentos baseados na deposição de camadas de 3-(trimetoxisililpropilmetacrilato (TMSPM) e/ou nitrato de cério sobre a liga de alumínio 2024 T-3 (AA2024 T-3). A resistência à corrosão foi avaliada por espectroscopia de impedância eletroquímica (EIE) durante a imersão em soluções de NaCl e Na2SO4 0,1molL-¹. Microscopia de força atômica (AFM), microscopia eletrônica de varredura (MEV) e espectrometria de dispersão em energia (EDS) foram utilizados para avaliar a superfície antes e após os tratamentos. Os resultados eletroquímicos mostraram que o nitrato de cério, quando presente entre duas camadas de TMSPM (camada depositada tipo sandwich), aumenta a resistência à corrosão. Este comportamento foi atribuído a presença de uma camada interna rica em silício e cério e outra mais externa rica em TMSPM, a qual aumenta o efeito barreira da camada. O capítulo II mostra um material hibrido orgânico-inorgânico carregado baseado em sílica, que foi obtido pelo método sol-gel. Esse híbrido foi usado como precursor para a síntese de um novo revestimento para ser usado sobre alumínio 99,999% e a liga de alumínio 2024-T3. A caracterização do material hibrido sintetizado foi feita por espectroscopia de ressonância magnética nuclear de carbono 13 (13C NMR) e análise termogravimétrica (TGA). O comportamento corrosivo desse revestimento híbrido foi avaliado em soluções de NaCl e Na2SO4 0,1molL-¹( pH:7), e em Na2SO4 0,3% (pH:3) atravês de técnicas de polarizações potenciodinâmicas e espectroscopia de impedância eletroquímica (EIE). Adicionalmente, o revestimento híbrido foi analisado por MEV e EDS. Experimentos de EIE feitos com o alumínio revestido em meio contendo sulfato (pH:7) e soluções contendo cloreto mostraram um aumento da resistência à corrosão comparada com o alumínio nu. Este fato foi interpretado baseado num processo de troca iônica entre o anion NO3- presente no filme hibrido pelos anions SO4-² ou Cl- presents na solução. Desta forma, este híbrido sol-gel permite a formação de um revestimento protetor para o alumínio, o qual mostra diferentes propriedades eletroquímicas de acordo com o contra-ion presente no filme. Para o liga AA2024T3 os testes realizados em meio de cloreto revelaram que este revestimento não apresenta propriedades protetora.Silanes coatings were deposited on aluminum alloy AA 2024 - T3, in order to obtain a protective film against corrosion. The chapter I aims at studying the corrosion behavior of treatments based on the deposition of layers of metacryloxypropylmethoxysilane (MAOS) and/or cerium nitrate on aluminum alloy 2024 T-3 (AA2024-T3). The corrosion resistance was evaluated by electrochemical impedance spectroscopy (EIS) during immersion in 0.1M Na2SO4 and NaCl solutions. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were also used to perform a surface analysis before and after the treatments. The electrochemical results show that cerium nitrate, when present between two layers of MAOS (sandwich-type deposited layer), improves the corrosion resistance. This can be attributed to the presence of an internal layer rich in silicium and cerium and another external MAOS layer, which further improves the barrier effect of the layer. The chapter II shows the charged organic-inorganic silica based hybrid material, containing the 1,4 diazoniabycicle[2.2.2]octane group that was obtained using the solgel method. This hybrid was used as precursor for the synthesis of a novel coating on 99.999% aluminum substrate. The characterization of the synthethysed hybrid material was carried out using NMR spectroscopy and Thermal Analysis. The corrosion behavior of this hybrid coating deposited on aluminum was evaluated in 0.1molL-¹ NaCl, Na2SO4 solution at pH 7 and in 0.3% (v/v) Na2SO4 solution at pH 3 by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). In addition, the hybrid coating was analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). EIS experiments performed with the coated aluminum in sulphate (pH:7) and chloride solutions have shown an improved corrosion resistance compared to the bare metal. This feature was interpreted on the basis of an ion-exhange process between the NO3ˉ anion contained in the hybrid film by the SO4-² or Cl- anions present in the solution. Thus, this novel hybrid sol-gel allows the formation of protective coating showing different properties according to the contra-ion present in the film. Tests performed with the coated aluminum alloy AA 2024-T3 in chloride media have showed that the protective effect of this coating is not adequate.
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Lopez-Garrity, Omar A. "Corrosion Inhibition Mechanisms of Aluminum Alloy 2024-T3 by Selected non-Chromate Inhibitors." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372077968.
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Boag, Adam Paull, and adam boag@gmail com. "The Relationship Between Microstructure and Stable Pitting Initiation in Aerospace Aluminium Alloy 2024-T3." RMIT University. Applied Science, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091028.114831.
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Aluminium alloys are essential to a variety of industry sectors, particularly transport, where they are used in the production of cars and aeroplanes. However, aluminium alloys are susceptible to degradation through corrosion which can compromise the integrity of components manufactured from this material. Therefore research into the means by which these alloys degrade is important. This thesis aims to understand how one of the more potentially damaging types of corrosion, known as pitting corrosion, occurs in the important aluminium alloy 2024-T3 (AA2024-T3). In order to study this phenomenon, this thesis first characterises the alloy microstructure in detail, particularly the type and distribution of intermetallic particles since these play an important role in corrosion processes. The microstructure was studied using an electron microprobe analysis of a 5 mm x 5 mm area of AA2024-T3 and some 80,000 particles were characterised. This investigation was one of the most comprehensive studies to date of any aluminium alloy. Of the particles studied, it was found that the major types included the S and θ phases and a number of compositions based around AlCuFeMn and AlCuFeMnSi. Depletion zones were an integral feature of the alloy microstructure. Pair correlation functions were used to determine the degree of clustering and it was found that there was both inter particle as well as intra particle clustering. Inter particle clustering was observed at length scales well beyond 50 µm. A detailed study of corrosion on AA2024-T3 was undertaken by examining the surface after corrosion over a time period spanning 2.5 minutes to 120 minutes. From this investigation, a hierarchy of the localised corrosion was observed as it was very apparent that particles of particular elemental compositions were more susceptible to attack much sooner than other compositions. Larger corrosion attack sites on the surface, which were called co-operative corrosion, were attributed to intermetallic clustering affects and changes in chemical composition such as Cu-enrichment. These results were used to develop a detailed model of the initiation of stable pitting corrosion in AA2024-T3, which will lead to a better understanding on how to prevent pitting attack on commercially important aluminium alloys. AA2024-T3 is rarely used in the polished state, for real world applications is it generally finished by mechanical or chemical processing. In the final part of this thesis, the influence of clusters on metal finishing was examined using a standard aluminium chemical deoxidiser. It was found that the etch rate of this deoxidiser increased dramatically with the increase in temperature. Under certain processing conditions only the intermetallic particles are etched out and these retain the history of the spatial distribution of the clustering of the intermetallic particles. This leaves a cluster of 'holes' which could trap metal finishing solution and lead to severe subsurface attack
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Chilukuri, Anusha. "Corrosion Inhibition by Inorganic Cationic Inhibitors on the High Strength Aluminum Alloy, 2024-T3." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343784869.
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Elaish, Reafat. "Influences of fluorine species on the anodizing behaviour of aluminium and AA 2024-T3 alloy." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/influences-of-fluorine-species-on-the-anodizing-behaviour-of-aluminium-and-aa-2024t3-alloy(7849513e-31b6-4f71-a6ee-126ee5221321).html.
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The present study investigates the effect of fluorine species during anodizing of aluminium and AA2024-T3 alloy in sulphuric acid and tartaric-sulphuric acid (TSA) electrolytes. The investigation comprises four main parts; (i) Effects of fluoride on barrier film formation on aluminium. (ii) Effects of fluoride and fluorozirconic acid (FZ) on porous film growth on aluminium in sulphuric acid. (iii) Effects of FZ on porous film growth on aluminium and AA 2024-T3 alloy in sulphuric acid and TSA. (iv) Effects on anodizing of other fluoroacids (fluoroboric (FB), fluorosilicic (FS) and fluorotitanic acid (FT)). The anodic films were examined by analytical scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, Rutherford backscattering spectroscopy, nuclear reaction analysis and glow discharge optical emission spectroscopy. The behaviour of fluoride ions during the growth of barrier-type films on aluminium was investigated in ammonium pentaborate solution with added sodium fluoride. Additions of up to 3.5 x 10-3 M sodium fluoride had a negligible influence on the film growth. In contrast, 3.5 x 10-2 M sodium fluoride reduced the efficiency to 60% as fluoride ions promoted field-assisted ejection of Al3+ ions from the film. Incorporated fluoride ions migrated inwards at a rate about twice that of O2- ions, forming a fluoride-rich layer at the film base. The study of the influence of FZ on formation of porous anodic films in sulphuric acid and TSA employed a range of anodizing voltages, electrolyte temperatures and anodizing times. Fluoroacid increased the growth rate, with a reducing influence as the temperature increased. The films contained fluoride and sulphate ions, zirconium was not detected. The fluoride concentration decreased with increasing temperature, whereas the sulphate concentration was unaffected. Anodizing aluminium and AA 2024-T3 alloy in other fluoroacids resulted in similar influences on the anodizing behaviour as FZ. The differences in growth rate, film composition and film morphology were comparatively small and did not show a systematic dependence on the type of fluoroacid employed. Boron, silicon and titanium were not detected in the films.
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Huang, I.-Wen Evan. "Uniform Corrosion and General Dissolution of Aluminum Alloys 2024-T3, 6061-T6, and 7075-T6." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469105977.
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Palomino, Luis Enrique Morales. "Caracterização microestrutural e eletroquímica de revestimentos ambientalmente amigáveis aplicados sobre a liga de Al 2024-T3." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-14012008-093144/.
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A crescente preocupação com o desenvolvimento sustentável, aliada com uma maior conscientização com relação à preservação do meio ambiente, tem incentivado pesquisas com a finalidade de encontrar substitutos ambientalmente amigáveis para os eficientes sistemas à base de cromo hexavalente (Cr6+), que são empregados como pré-tratamento em ligas de alumínio de alta resistência utilizadas na indústria aeronáutica. Neste trabalho, o desempenho do silano BTSE (Bis-1,2-(trietoxisilil) etano) como método de proteção contra a corrosão da liga de alumínio 2024-T3 foi investigado utilizando técnicas de caracterização eletroquímicas, microestruturais e químicas. Para melhorar as propriedades anticorrosivas do sistema, a camada de silano foi modificada pela introdução de aditivos, tendo sido estudados também sistemas em bi-camada. Efeitos das condições de cura (tempo e temperatura) do BTSE e da quantidade de modificantes sobre as propriedades dos substratos revestidos também foram avaliados. Para os estudos eletroquímicos, realizados em solução de NaCl 0,1 M, foram empregadas a espectroscopia de impedância eletroquímica (EIS) e curvas de polarização potenciodinâmica anódica e catódica. As técnicas de caracterização morfológica e microestrutural foram microscopia de força atômica (AFM), microscopia eletrônica de varredura (SEM) e medidas de ângulo de contato. A caracterização da composição e do estado químico da camada foi realizada usando as espectroscopias por energia dispersiva de Raios-X (EDS), de infravermelho (IR) e de fotoelétrons excitados (XPS). Os resultados dos ensaios de corrosão mostraram que a adição dos modificantes à camada de BTSE melhora o desempenho anticorrosivo do sistema, o qual também teve seu comportamento melhorado quando utilizado em forma de bi-camada. Verificou-se que um excesso de aditivos tende a deteriorar as propriedades protetoras do silano, e que o aumento do tempo e da temperatura de cura é benéfico para as propriedades anticorrosivas dos diferentes sistemas. Os resultados dos ensaios de caracterização química e microestrutural também detectaram que os modificantes contribuem para uma melhor cobertura do substrato pela camada de silano, assim como para uma maior reticulação da mesma, sem, no entanto, modificar sua estrutura química e física.The increasing concern with sustainable development, allied with a stronger awareness with environmental preservation, has stimulated researches in order to find environmentally friendly substitutes to replace the efficient hexavalent chromium-based pre-treatment systems (Cr6+) used to protect high-strength aluminium alloys employed in the aircraft industry. In this work, the performance of BTSE (bis-1, 2-(triethoxysilyl) ethane) as a protection method against corrosion of aluminium alloy 2024-T3 was investigated using electrochemical, microstructural and chemical characterization techniques. In order to improve the system anticorrosion properties, modifiers were added to the silane layer, and bi-layers systems were also tested. The effects of the silane curing conditions (time and temperature) and of the modifiers amounts on the properties of the layers were also evaluated. Electrochemical impedance spectroscopy (EIS) and anodic and cathodic potentiodynamic polarization curves were employed for the electrochemical studies, which were performed in 0.1 M NaCl solution. For microstructural and morphological characterization, atomic force microscopy (AFM), scanning electron microscopy (SEM) and contact angle measurements were used. The chemical state and the composition of the different layers were evaluated using X-ray photoelectrons (XPS), infrared (IR) and X-ray dispersive energy (EDS) spectroscopy. The results of the corrosion studies have shown that the addition of modifiers to the BTSE layer improves its anticorrosion performance, which was also improved in the bi-layers systems. It was also verified that addition of modifiers excess hinders the performance of the layers, as well as that increasing curing time and temperature are beneficial to the anticorrosion properties of the systems. The results of the different chemical and microstructural analyses showed that the modifiers contribute to better substrate coverage by the silane layer, as well as to a more complete reticulation. However, this does not imply in modifications of the chemical and physical structure of the layer.
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Cendron, Suelen Weimer. "Revestimentos à base de BTSE/GPTMS como tratamento anticorrosivo para a liga de alumínio 2024-T3." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/147232.
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A liga de alumínio AA2024-T3 é largamente empregada na indústria aeronáutica devido à suas propriedades mecânicas, porém essa liga apresenta baixa resistência à corrosão. Cromatos são usualmente empregados como tratamento anticorrosivo e apresentam bom desempenho quando aplicados sobre alumínio e suas ligas. No entanto, o uso de espécies que contenham Cr(VI) vem sendo restringido devido à alta toxicidade e carcinogenicidade. Silanos representam uma alternativa à cromatização e apresentam vantagens como ser uma tecnologia ambientalmente correta, ter bom desempenho anticorrosivo e promover adesão da tinta posteriormente aplicada. O presente trabalho investigou o desempenho de filmes de 3-glicidoxipropiltrimetoxisilano (GPTMS) combinado com 1,2-Bis(trietoxisilil)etano (BTSE) depositados sobre a liga de alumínio 2024-T3. O efeito do pré-tratamento da superfície metálica também foi estudado, sendo o desengraxe alcalino seguido de imersão em ácido nítrico o que apresentou melhor resultado. A adição dos ácidos fosfônicos 1,2-diaminoetanotetrametileno fosfônico (EDTPO) e ácido octadecilfosfônico (ODPA) ao banho silanizante foi avaliada. Verificou-se melhor desempenho anticorrosivo para o sistema composto por 50% etanol 46% água 1% GPTMS 3% BTSE com incorporação de EDTPO na concentração de 3,75x10-5 mol L-1. O comportamento corrosivo da liga e dos filmes foi estudado utilizando Espectroscopia de Impedância Eletroquímica (EIE) após diferentes tempos de imersão em NaCl 0,05 mol L-1. A caracterização dos diferentes sistemas investigados foi realizada através das técnicas de Microscopia de Força Atômica (AFM), Espectroscopia Fotoeletrônica de raios x (XPS), Ângulo de Contato em Água (WCA) e Espectroscopia de Infravermelho (IV). Os resultados obtidos indicam que o recobrimento da liga AA2024-T3 por filmes formados por GPTMS e BTSE, na proporção otimizada, modificados com o ácido fosfônico EDTPO permite retardar o desenvolvimento de processos corrosivos.AA2024-T3aluminum alloy is widely used in the aerospace industry due to their mechanical properties, but this alloy has poor corrosion resistance. Chromate are usually employed as anticorrosive treatment and perform well when applied on aluminum and its alloys. The use of species containning Cr (VI) has been restricted due to their high toxicity and carcinogenicity. Silanes represent an alternative to chromate and show advantages such as: being an environmentally friendly technology, presenting good anti-corrosive performance and promoting adhesion of the subsequently applied paint. This study investigated the performance of 3-glycidoxypropyl trimethoxysilane films (GPTMS) combined with 1,2-Bis(triethoxysilyl)ethane (BTSE) deposited on the 2024-T3 aluminum alloy. The effect of pretreatment of the metal surface has also been studied, and the alkaline degreasing followed by immersion in nitric acid, showed the best results. The addition of phosphonic acids 1,2-diaminoethanetetrakismethylenephosphonic acid (EDTPO) and Octadecylphosphonic acid (ODPA) on the silane bath was evaluated. Best corrosion performance was verified for the system composed by 50% ethanol 46% water 1% GPTMS 3% BTSE by adding EDTPO (3,75x10-5molL-1). The alloy and films corrosion behavior was studied using Electrochemical Impedance Spectroscopy (EIS) after different immersion times in NaCl 0.05 mol L-1. The characterization of the investigated systems was carried out by Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), Water Contact Angle (WCA) and Infrared Spectroscopy (IR). The results indicate that covering AA2024-T3 alloy with films formed by GPTMS and BTSE in the optimized ratio, modified with phosphonic acid EDTPO, allows slowing the development of corrosive processes.
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Shivalli, Praveen Smith Bert. "The effect of dents on fatigue life and fatigue crack growth of aluminum 2024-T3 bare sheet." Diss., A link to full text of this thesis in SOAR, 2006. http://soar.wichita.edu/dspace/handle/10057/681.
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Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering."December 2006." Title from PDF title page (viewed on Sept. 24, 2007). Thesis adviser: Bert Smith. Includes bibliographic references (leaves 62-64).
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Ahn, Joseph. "Experimental characterisation and numerical simulation of fibre laser welding of AA 2024-T3 and Ti-6Al-4V." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/53827.
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The aircraft industry has long recognised the importance of climate protection and the benefits of reducing weight for the production of cost effective and fuel efficient aircraft structures. Fibre laser welding provides advantages over conventional riveting, mainly in terms of weight reduction and time saving. However, significant changes in microstructure, metallurgical state and associated mechanical properties occur in welded joints. Such changes can result in residual stresses, distortions and defects formation in the welded structure, thus significantly influencing the performance and service life. In order to maintain structural integrity of welded structures, the relationship between welding process and performance of the structure needs to be fully assessed. In this thesis, comprehensive relationships between materials, welding process, microstructure and mechanical properties of welded joints were established. Welding parameters including power density, laser power, welding speed, focal position, filler metal feed rate and shielding gas composition were optimised to produce high quality full penetration welds. Solidification cracking was found to be a critical issue in AA 2024-T3 when welding without filler metal. The addition of filler metal reduced its crack sensitivity but it was also necessary to provide the optimum feed rate to avoid welding defects and keyhole instability. Sufficiently high laser power and low welding speed were required for full penetration and also to minimise welding defects. Both argon and helium shielding gases were found to be effective since only weakly ionised laser induced vapour plume was formed rather than strongly ionised plasma. Softening in AA204-T3 deteriorated the plastic straining capacity of the weld due to confined plasticity development within the weld. A poor weld quality resulted in a mixed mode of brittle and ductile failure and contained micro porosities and hot cracks, whereas, a good weld quality led to a ductile mode with significantly less welding defects. In the case of Ti-6Al-4V, the strength was the greatest in the weld as a result of martensitic microstructure formed during fast cooling rates. Local plastic deformation was the lowest in the weld and therefore, failed in the parent material but at the cost of reduced ductility relative to the unwelded parent tensile specimens. The residual stresses and distortions due to time dependent and localised heating imposed during fibre laser welding were numerically simulated with thermal and mechanical boundary conditions integrated in the finite element models including post weld heat treatment, mechanical stress relieving treatment and various clamping arrangements. Mechanical boundary conditions had relatively small influence on residual stresses in thin sheets of butt welded specimens, whereas, greater restraints led to higher residual stresses and lower restraints led to lower residual stresses in T-joint specimens. Non-isothermal diffusional and diffusionless phase transformations in Ti-6Al-4V were modelled and their influence on residual stresses and distortions was examined. Phase transformations only had a small influence on the magnitude and distribution of residual stresses and distortions because the level of internal stresses due to phase transformation remained low unlike other materials which exhibit greater differences in the specific volumes between phases. Post weld heat treatment (PWHT) induced diffusional phase transformations via decomposition of martensite into α. It also decreased the magnitude of y stresses to the yield strength of Ti-6Al-4V at the treatment temperature by releasing the locked-in stresses. Mechanical stress relieving was also studied for reducing residual stresses and distortions, by means of plastic deformation applied during as well as after welding. When the load reached more than 50% of its yield strength, the stresses became compressive. Residual stresses were experimentally measured using X-ray and neutron diffraction techniques They were found to be dependent on the crystallographic hkl plane due to the presence of microscopic stresses. In the case of Ti-6Al-4V, the reflections were weak and only few times larger than the background due its highly incoherent cross-section. In addition, texture in Ti-6Al-4V weld also contributed to lower intensity counts observed during measurements. As a result, only certain peaks were detected in certain orientations. The Y residual stresses in the welding direction were very high but not as high as the yield strength of the material at room temperature for both AA 2024-T3 and Ti-6Al-4V. They were largely tensile in nature only within the weld and tended to be weakly compressive in the rest of the specimen. Comparative analyses between experimental and numerical results showed good agreements, proving the robustness of the finite element models.
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Morabito, Anna Eva. "Analyse thermomécanique des effets thermoélastiques et dissipatifs associés au comportement en fatigue de l'alliage d'aluminium 2024 T3." Montpellier 2, 2003. http://www.theses.fr/2003MON20183.
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Oliveira, Fernando Silva de. "Análise de tensões residuais por difração de raios-x em chapas de alumínio 2024-T3 soldadas por FSW." Instituto Tecnológico de Aeronáutica, 2011. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3022.
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A soldagem por FSW (Friction Stir Welding) tem como principal característica o fato do material não fundir durante o processo. Isso ocorre porque as temperaturas atingidas durante a soldagem são inferiores à temperatura de fusão do material, sendo essa uma das vantagens desse processo em relação aos processos convencionais. Entretanto, o calor local gerado é suficiente para o aparecimento de tensões residuais no material. As tensões residuais de soldagem modificam as propriedades mecânicas do material, podendo causar falhas prematuras em estruturas. A medição de tensões residuais é um processo relativamente caro e demorado. Assim, torna-se interessante estimar o comportamento das tensões residuais através de outro parâmetro, como a dureza, que um processo mais barato de rápida medição. Dessa forma, esse trabalho consiste na análise das tensões residuais e comparação com a dureza do Al 2024 T3, soldado por FSW.
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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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Fontana, Álvaro. "Utilização de polianilina como revestimento protetor contra corrosão das ligas de alumínio 2014 F, 2024 T3 e 7075 O." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-25102007-165457/.
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É grande o uso do alumínio em virtude de sua viabilidade técnica e econômica além da alta proteção frente à corrosão conferida pelo filme de óxido de alumínio formado em sua superfície. Neste trabalho foram realizadas deposições de filme de polianilina (PAni) sobre ligas de alumínio AA-2014, AA-2024 e 7075 O. Os experimentos de eletropolimerização foram realizados por voltametria cíclica e cronoamperometria a partir de soluções aquosas contendo ácido fosfórico, ácido sulfâmico e anilina. Para a caracterização dos filmes obtidos sobre as superfícies das ligas foram utilizadas as técnicas de espectroscopia de infravermelho, microscopia eletrônica de varredura e espectroscopia de impedância eletroquímica. Os ensaios de corrosão foram realizados em meio agressivo ao alumínio, solução aquosa de NaCl 0,6 mol L-1 por medidas de polarização potenciodinâmica. Também foi estudada a nucleação dos filmes de PAni por cronoamperometria sobre as mesmas ligas. A partir da caracterização dos polímeros, os resultados demonstram diferenças estruturais entre os filmes de PAni decorrentes do meio ácido utilizado na eletropolimerização, que influencia na proteção contra corrosão. Estruturalmente os filmes eletropolimerizados em meio de ácido fosfórico são mais porosos em relação ao filme de PAni obtido em meio de ácido sulfâmico. Tanto para os filmes obtidos a partir de soluções aquosas de ácido fosfórico como de ácido sulfâmico ocorreram variações estruturais dos filmes após os ensaios de corrosão. Os parâmetros eletroquímicos extraídos das curvas potenciodinâmicas e das análises de impedância demonstram que os filmes obtidos protegem as ligas estudadas contra corrosão. Considerando-se o filme no estado desdopado, para a liga AA-2014, houve um deslocamento no potencial de corrosão de 61,2 mV para valores mais positivos em relação a liga sem recobrimento. Para as outras ligas esse deslocamento foi de 176,1 mV para a liga AA-2024 e 134,3 mV para a liga 7075, evidenciando assim uma maior proteção contra corrosão. Os estudos de corrosão evidenciam que os filmes de PAni podem ser alternativas viáveis aos outros meios protetores utilizados contra corrosão.Aluminum is widely used due to its technical and economic advantages, as well as due to its high level of corrosion protection provided by the oxide film formed on the surface of the metal. In the current study deposition of polyaniline (PAni) on three different Al alloys (AA-2014 F, AA-2024 T3 and 7075 O) was studied. The electrodepositions were realized from aqueous solutions of either phosphoric acid or sulphamic acid that contained the aniline monomer, using the techniques of cyclic voltammetry and chronoamperometry. The films were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). To evaluate the resistance of the films under conditions aggressive to Al, potentiodynamic polarization curves were performed in 0,6 mol L-1 NaCl. The nucleation of the films on the aluminum alloys was also investigated using chronoamperometry. Characterization of the PAni films obtained demonstrates that the use of different acids results in distinct structural characteristics, which influence their corrosion protection properties. Structurally the electro-deposited PAni films are more porous when phosphoric acid is used compared to sulphamic acid. After the corrosion assays structural differences are observed, independent of the acid used in the electrosynthesis. Data obtained from the potentioidynamic polarization curves and the impedance measurements indicate that the films obtained protect the alloys studied against corrosion. Considering the film in the undoped form for the alloy AA-2014 F, there was a positive shift in the corrosion potential of 61.2 mV. For the AA-2024 T3 and 7075 O alloys the shifts were 176.1 and 134.4 mV, respectively, indicating a greater degree of corrosion protection. The present study demonstrates that PAni films are viable alternatives to other protection methods.
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Goetze, Paul Aaron. "A Comparative Study of 2024-T3 and 7075-T6 Aluminum Alloys Friction Stir Welded with Bobbin and Conventional Tools." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1556807142415698.
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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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Bonhin, Eduardo Pires. "Estudo do processo de furação do laminado metal fibra de alumínio 2024-T3 e epóxi reforçado com fibra de vidro /." Guaratinguetá, 2019. http://hdl.handle.net/11449/181761.
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Orientador: Marcos Valério RibeiroResumo: A utilização de materiais compósitos em componentes do setor aeronáutico vem crescendo muito nos últimos anos. Isso se deve ao fato destes materiais apresentarem boas propriedades mecânicas, aliadas a sua baixa massa específica. Dentre estes, os laminados metal fibra, são uma classe de materiais que vem ganhando destaque. Contudo seu emprego na maioria dos casos, requer a confecção de furos, algo que é muito complexo e pode causar danos ao material. Portanto, o objetivo desta pesquisa foi estudar o processo de furação em cheio de um laminado de metal fibra de alumínio 2024-T3/epóxi/fibra de vidro apoiado no alumínio 7075, aplicando diferentes parâmetros de usinagem para avaliar a influência na qualidade dos furos e o desgaste das ferramentas, correlacionando com a potência consumida, vibração, força de avanço, variações dimensionais nos furos e alteração das propriedades mecânicas do material. Para tal, o material foi processado via moldagem por compressão a quente e caracterizado por meio dos ensaios de cisalhamento interlaminar (ILSS), cisalhamento por compressão (CST) e Lap shear. Posteriormente, foram realizados processos de furação utilizando 4000, 6000 e 8000 rpm, bem como avanços de 0,05; 0,1 e 0,2 mm/rot. Após a análise dos resultados, pode-se concluir que os parâmetros influenciaram nos dados de potência, vibração e força de avanço, bem como houve variação significativa nos diâmetros obtidos, sendo que o melhor resultado ocorreu para combinação de 6000 rpm com 0,05mm... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The use of composite materials in aeronautical components has been increased in the last years. This is due to these material presente good mechanical properties, allied with low specific mass. Among them, the fiber metal laminated (FML) are a class of materials that has been gaining prominence. However, its use in most cases requires the drilling of holes, which is very complex and can cause damage to the material. Therefore, the objective of this research was to study the conventional drilling process in aeronautical aluminum structures reinforced with fiber metal laminates. Applying different machining parameters, to evaluate the delamination and the wear tools, correlating with the power consumed, vibration, advance force, dimensional variations in the holes and variation of the mechanical properties on material. For this, the material was processed by hot compression molding and characterized by interlaminar shear stress (ILSS), compression shear test (CST) and Lap-shear. Afterwards, drilling processes were carried out using 4000, 6000 and 8000 rpm, as well as an advance of 0.05; 0.1 and 0.2 mm / rot. After the analysis of the results, it was possible to conclude that the parameters influenced the data of power, vibration and force of advance, as well as there was significant variation in the diameters obtained, being the best result occurred for a combination of 6000 rpm with 0,05mm / rot. It can also be stated that there is a tendency of shear strength of the Lap Shear... (Complete abstract click electronic access below)
Mestre
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BUGARIN, ALINE de F. S. "Estudo da resistência à corrosão das ligas de alumínio 2024-T3 e 7475-T651 soldadas por fricção e mistura (FSW)." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28030.
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O processo de soldagem por fricção e mistura (FSW) tem despertado grande interesse nos últimos anos e tornou-se uma alternativa para unir materiais de baixa soldabilidade, como as ligas de alumínio das séries 2XXX e 7XXX, as quais são empregadas na estrutura das aeronaves, por possuírem elevada relação resistência/peso. O processo FSW, todavia, causa mudanças microestruturais nos materiais soldados, particularmente na zona misturada (ZM) e nas zonas termicamente (ZTA) ou termomecanicamente (ZTMA) afetadas. Estas mudanças geralmente interferem no desempenho frente à corrosão das ligas soldadas. No presente estudo, a resistência à corrosão das ligas de alumínio 2024-T3 e 7475-T761, unidas pelo processo FSW foi investigada em solução 10 mM de NaCl. Ensaios de visualização em gel ágar-ágar e de imersão associados a técnicas microscópicas foram realizados para investigar o efeito do acoplamento galvânico na corrosão das diferentes regiões da junta soldada. Os resultados do ensaio de visualização em gel mostraram que, quando acopladas, a liga 2024 atua como cátodo e a 7475 como ânodo. Os ensaios de imersão revelaram acoplamento galvânico entre as ligas na zona misturada (ZM). A região mais afetada pela corrosão foi a ZTMA da liga 7475, com corrosão intergranular desde as primeiras horas de imersão. A influência do processo de soldagem na resistência à corrosão das duas ligas de alumínio foi investigada por ensaios eletroquímicos. Os ensaios eletroquímicos adotados foram medidas de potencial de circuito aberto (PCA) em função do tempo de exposição ao meio corrosivo, espectroscopia de impedância eletroquímica (EIE) e curvas de polarização potenciodinâmica. Os ensaios de polarização mostraram elevada atividade eletroquímica na zona de mistura indicada pelos altos valores de densidade de corrente em comparação com as demais zonas testadas. Os resultados de EIE globais mostraram que nas primeiras horas de exposição ao eletrólito o processo de corrosão foi predominantemente controlado pela liga 7475; todavia, com o tempo de exposição ao eletrólito, a corrosão passou a ser controlada pela liga 2024.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Bugarin, Aline de Fátima Santos. "Estudo da resistência à corrosão das ligas de alumínio 2024-T3 e 7475-T651 soldadas por fricção e mistura (FSW)." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-26102017-141238/.
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O processo de soldagem por fricção e mistura (FSW) tem despertado grande interesse nos últimos anos e tornou-se uma alternativa para unir materiais de baixa soldabilidade, como as ligas de alumínio das séries 2XXX e 7XXX, as quais são empregadas na estrutura das aeronaves, por possuírem elevada relação resistência/peso. O processo FSW, todavia, causa mudanças microestruturais nos materiais soldados, particularmente na zona misturada (ZM) e nas zonas termicamente (ZTA) ou termomecanicamente (ZTMA) afetadas. Estas mudanças geralmente interferem no desempenho frente à corrosão das ligas soldadas. No presente estudo, a resistência à corrosão das ligas de alumínio 2024-T3 e 7475-T761, unidas pelo processo FSW foi investigada em solução 10 mM de NaCl. Ensaios de visualização em gel ágar-ágar e de imersão associados a técnicas microscópicas foram realizados para investigar o efeito do acoplamento galvânico na corrosão das diferentes regiões da junta soldada. Os resultados do ensaio de visualização em gel mostraram que, quando acopladas, a liga 2024 atua como cátodo e a 7475 como ânodo. Os ensaios de imersão revelaram acoplamento galvânico entre as ligas na zona misturada (ZM). A região mais afetada pela corrosão foi a ZTMA da liga 7475, com corrosão intergranular desde as primeiras horas de imersão. A influência do processo de soldagem na resistência à corrosão das duas ligas de alumínio foi investigada por ensaios eletroquímicos. Os ensaios eletroquímicos adotados foram medidas de potencial de circuito aberto (PCA) em função do tempo de exposição ao meio corrosivo, espectroscopia de impedância eletroquímica (EIE) e curvas de polarização potenciodinâmica. Os ensaios de polarização mostraram elevada atividade eletroquímica na zona de mistura indicada pelos altos valores de densidade de corrente em comparação com as demais zonas testadas. Os resultados de EIE globais mostraram que nas primeiras horas de exposição ao eletrólito o processo de corrosão foi predominantemente controlado pela liga 7475; todavia, com o tempo de exposição ao eletrólito, a corrosão passou a ser controlada pela liga 2024.Friction stir welding (FSW) has roused great interest in recent years and it is now an alternative for joining materials of low weldability, such as the aluminum alloys of the 2XXX and 7XXX series, used in the aircrafts structure due to their high strength /weight ratio. However, FSW causes material microstructural changes, mainly in the stir zone (SZ), the heat affected zone (HAZ) or thermomechanically (TMAZ) affected zones of the materials welded. These generally interfere with the corrosive performance of the welded joint. In the present study, the corrosion resistance of the 2024-T3 and 7475-T761aluminum alloys, joined by FSW was investigated in 10 mM NaCl electrolyte. Agar-agar gel and immersion tests associated with microscopic techniques were performed to investigate the effect of galvanic coupling between the welded materials. Results from this test showed that, when galvanically coupled, the 2024 alloy acts as cathode and the 7475 as anode. Immersion tests revealed galvanic coupling between the alloys in the SZ. The zone most susceptible to corrosion was the TMAZ of the 7475. Intergranular corrosion was observed in this zone since the first hours of immersion. The influence of the welding process on the corrosion resistance of the alloys was also evaluated by electrochemical tests. The electrochemical tests adopted were open circuit potential measurements (OCP) as a function of time of exposure to the electrolyte, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. The polarization tests showed high electrochemical activity in the stir zone indicated by the high current densities measured comparatively to the other tested zones. The global EIS results indicated that in the first few hours of exposure to the electrolyte the corrosion process was predominantly controlled by the 7475 alloy; however, with time of exposure to the electrolyte, the corrosion was controlled by alloy 2024.
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Roungos, Ioannis C. "The effect of sequential action of corrosion and fatigue on fatigue crack initiation and propagation in 2024-T3 aluminium alloy." Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/11122.
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The influence of sequential action of corrosion and fatigue on fatigue behaviour of 2024- T3 aluminium alloy was investigated. EXCO solution was used for corrosion development. Corrosion evolution and penetration were investigated in terms of exposure time, dimensional characteristics, orientation, microstructure of material, incremental corrosion application and sequential application of corrosion and fatigue. Single Edge Notch Tensile specimens were used in the fatigue-corrosion tests. Fatigue intervals were interrupted by corrosion application. Four fatigue intervals and four corrosion segment times were incorporated in the test matrix. The results of fatigue ínitiation, propagation and total life were compared to the virgin and pre-corroded materials' behaviour. The main mechanisms of crack acceleration and arrest were identified and discussed relative to the morphology of corrosion development. Finally a comparison was tried between the experimental lives and the predicted ones, calculated from two crack growth packages using the most conservative approach.
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Roungos, I. C. "The effect of sequential action of corrosion and fatigue on fatigue crack initiation and propagation in 2024-T3 aluminium alloy." Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/11122.
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The influence of sequential action of corrosion and fatigue on fatigue behaviour of 2024-
T3 aluminium
alloy was investigated. EXCO solution was used for corrosion
development. Corrosion evolution and penetration were investigated in terms of
exposure time, dimensional characteristics, orientation, microstructure of material,
incremental corrosion
application and sequential application of corrosion and fatigue.
Single Edge Notch Tensile specimens were used in the fatigue-corrosion tests. Fatigue
intervals were
interrupted by corrosion application. Four fatigue intervals and four
corrosion
segment times were incorporated in the test matrix. The results of fatigue
ínitiation, propagation and total life were compared to the virgin and pre-corroded
materials' behaviour. The main mechanisms of crack acceleration and arrest were
identified and discussed relative to the
morphology of corrosion development. Finally a
comparison was tried between the experimental lives and the predicted ones, calculated
from two crack
growth packages using the most conservative approach.
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Queiroz, Fernanda Martins. "Estudo do comportamento de corrosão dos intermetálicos presentes na liga AA 2024-T3, por meio de técnicas de microscopia associada a técnicas eletroquímicas." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-17082009-152449/.
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A liga de alumínio AA2024-T3, amplamente utilizada na indústria aeroespacial, apresenta elevada resistência mecânica conferida pela adição de elementos de liga, principalmente o Cu, que formam precipitados finamente distribuídos e coerentes com a matriz, durante o processo de envelhecimento controlado. No entanto, durante este processo, também se formam intermetálicos (IMs) maiores com composição e atividade eletroquímica diferentes da matriz, tornando a liga altamente suscetível a processos de corrosão localizada. A literatura apresenta diversos trabalhos sobre o estudo da corrosão da AA2024-T3 associada à presença dos IMs, porém, o tema ainda é bastante controverso, e muitos aspectos precisam ser estudados com mais detalhes ou mesmo ainda desvendados. Nos últimos anos, técnicas de microscopia de alta resolução, como a microscopia eletrônica de transmissão (TEM) e microscopia eletrônica de varredura (MEV), associadas à espectroscopia por energia dispersiva de raios X (EDS) e a microscopia de força atômica (AFM) bem como técnicas eletroquímicas convencionais e localizadas têm auxiliado nestas pesquisas. Na presente tese serão apresentados os resultados dos estudos realizados sobre a corrosão da liga AA 2024-T3 em soluções de cloreto de baixa concentração. A investigação foi realizada aliando as técnicas de caracterização anteriormente descritas com técnicas eletroquímicas tradicionais: acompanhamento do potencial de circuito aberto (OCP) com o tempo, curvas de polarização (CP) e espectroscopia de impedância eletroquímica (EIS) e técnicas com elevado poder de resolução espacial: como a técnica do eletrodo vibratório de varredura (SVET). A caracterização microestrutural confirmou a heterogeneidade dos IMs, e como contribuições principais, evidenciou a existência de fases secundárias (cristalinas ou não) no interior dos próprios IMs e que a matriz da liga nas proximidades dos IMs apresenta microestrutura variável, todos estes aspectos podendo contribuir de maneira sinérgica para o complexo comportamento de corrosão exibido pelos IMs. Além do mais, mostrou-se que na corrosão os IMs estão submetidos a ataque eletroquímico e químico, este último ocasionado por aumento local do pH. Os resultados dos testes eletroquímicos convencionais mostraram que nas condições empregadas no presente estudo a corrosão da liga é dominada pelo comportamento de corrosão dos IMs, e que, dentro deste contexto, o transporte de oxigênio até os sítios catódicos formados pelos IMs, ao invés da concentração de cloretos, parece ser a etapa controladora da velocidade de corrosão. Por outro lado o tratamento da região em altas freqüências dos diagramas de EIS se mostrou um importante aliado na compreensão dos processos que ocorrem na interface quando da corrosão da liga. No que se refere às técnicas localizadas, a viabilidade do uso da técnica do eletrodo vibratório de varredura (SVET) para estudo do início da corrosão na AA2024-T3 foi avaliada e um sistema para aquisição de dados experimentais por espectroscopia de impedância localizada (LEIS) foi montado e validado. A SVET confirmou que a atividade eletroquímica da liga AA2024-T3 se inicia desde os primeiros instantes de imersão do material no eletrólito teste.The AA2024-T3 aluminium alloy is largely used in the aerospace industry. It has high mechanical properties due to the presence of alloying elements, mainly copper, that form finely distributed precipitates coherent with the matrix, during controlled aging treatment. However, during this process, large intermetallics (IMs) are also formed with composition and electrochemical activity different from the matrix, making the alloy highly susceptible to localized corrosion. Many works have been published in literature on the corrosion behavior of the AA2024-T3 alloy associated to the presence of IMs, however, the subject is still controversial and many aspects need further detailed investigation. In the last years, high resolution microscopy techniques, such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM) associated to X-ray energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM) simultaneously with conventional and localized electrochemical techniques have largely contributed to these studies. In the present work the results of studies carried out on the corrosion behavior of the AA 2024-T3 alloy in chloride solutions of low concentration are presented. The investigation was undertaken by combining the above characterization techniques with conventional electrochemical techniques: open circuit potential (OCP) measurements as a function of immersion time, polarization curves (PC) and electrochemical impedance spectroscopy (EIS) and also techniques of high spatial resolution such as scanning vibrating electrode technique (SVET). The microstructural characterization of the AA 2024-T3 alloy corroborated the heterogeneous nature of the IMs, and as the main contributions, evidenced the presence of secondary phases (either crystalline or amorphous) inside the IMs and the heterogenous microstructure of the matrix at the vicinity of the IMs. All these properties might sinergically contribute to the complex corrosion behavior showed by the IMs. Besides, it was also found that the IMs suffer electrochemical and chemical attack, this last type being caused by local pH increase. The results of the conventional electrochemical techniques showed that under the conditions adopted in the present study, the corrosion of the AA2024-T3 is ruled by the corrosion behavior of the IMs. In this perspective, the oxygen transport to the cathodic sites generated by the IMs rather than the chloride concentration, seems to be the controlling step of the corrosion rate. On the other hand, the analysis of the EIS high frequency data allowed to elucidate the the interfacial processes occurring during the corrosion of the aluminium alloy investigated. The viability of the use of SVET to study the corrosion initiation in the AA2024-T3 was evaluated and a system for experimental data acquisition by localized electrochemical impedance spectroscopy was installed and validated. The SVET showed that the electrochemical activity of the AA2024-T3 takes place since the first periods of immersion in the test electrolyte.
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André, Natália Manente. "Friction spot joining of aluminum alloy 2024-t3 and carbon-fiber-reinforced polyphenylene sulfide composite laminate with additional pps film interlayer." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/8275.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Friction Spot Joining (FSpJ) is a prize-winning joining technique for hybrid metal-polymer composite structures. This master thesis was devised to investigate the feasibility of FSpJ of metal-composite structures with additional film interlayer. Friction spot joints of aluminum alloy 2024-T3 and carbon-fiberreinforced polyphenylene sulfide laminate composite with additional PPS film interlayer were successfully produced. The highest peak temperature achieved during the joining process was 417°C. DSC analysis demonstrated that the degree of crystallinity decreased for the composite (from 22% to 12%) and increased for the PPS film (from 7% to 27%) after joining. TGA analysis indicated that no extensive thermo-mechanical degradation induced by the joining process occurred. The main bonding mechanisms of FSp joint were identified as macro- and micro-mechanical interlocking, as well as adhesion forces. The process-related microstructural effects were evaluated and correlated to the local mechanical performance of the joining parts through micro and nanohardness. Further, mechanical grinding, sandblasting and plasma activation surface pre-treatments were performed on the composite part to enhance the adhesion between the joining parts. The generated surface features due to the surface pre-treatments were correlated to the mechanical performance of the joints. Sandblasted specimens showed the best mechanical performance among the surface pre-treatments used in this work. The lap shear strength of joints with interlayer (2703 ± 114 N up to 3069 ± 166 N) was up to 55% higher than the corresponding joints without film. The fatigue life of the joints with interlayer was 4 times longer in comparison with those without interlayer; superior fatigue strength was also observed. The durability of the joints was evaluated through hydrothermal accelerated aging; the maximum reduction in initial strength was 12.4% for 28 days of aging. Finally, the failure mechanisms of the joints were discussed, demonstrating a mixture of adhesivecohesive failure mode.
A União Pontual por Fricção (FSpJ) é uma técnica internacionalmente premiada para união de estruturas híbridas metal-compósito polimérico. Esta dissertação de mestrado investigou a viabilidade técnica da produção de juntas metal-compósito com filme polimérico intermediário através do FSpJ. Juntas de alumínio 2024-T3 e laminado compósito de poli(sulfeto de fenileno) (PPS) reforçado com fibras de carbono com filme intermediário de PPS foram produzidas com sucesso. A máxima temperatura processual identificada foi de 417°C. Análises de DSC demonstraram decréscimo no grau de cristalinidade do compósito (de 22% para 12%) e acréscimo no caso do filme intermediário (de 7% para 27%) depois de submetidos ao processo de união. Análises de TGA não identificaram evidências de ocorrência de degradação termomecânica dos componentes poliméricos das juntas induzida pelo FSpJ. Os principais mecanismos de união identificados na interface das juntas foram macro- e micro-ancoramento mecânico, além de forças adesivas. As mudanças microestruturais induzidas pelo processo de união foram investigadas e correlacionadas com o desempenho mecânico local dos componentes da junta através de medidas de micro e nanodureza. Pré-tratamentos superficiais de lixamento, jateamento de areia e ativação por plasma foram realizados no componente compósito a fim de aprimorar a adesão entre os componentes a serem unidos. As superfícies pré-tratadas foram caracterizadas e suas propriedades foram correlacionadas com a resistência mecânica das juntas correspondentes. As amostras jateadas produziram juntas com a melhor resistência mecânica entre os pré-tratamentos superficiais investigados neste estudo. A resistência ao cisalhamento das juntas com filme (2703 ± 114 N até 3069 ± 166 N) apresentou-se até 55% superior à resistência das respectivas juntas sem filme. A vida em fadiga das juntas com filme apresentou-se cerca de 4 vezes mais longa em comparação às juntas sem filme. A durabilidade das juntas foi investigada através de envelhecimento hidrotérmico acelerado, sendo que a máxima redução em resistência ao cisalhamento foi de 12,4% para 28 dias de envelhecimento. Finalmente, os mecanismos de falha das juntas foram discutidos, demonstrando a predominância do modo coesivo de falha.
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Costa, Douglas Henrique da Silva [UNESP]. "Estudo do efeito do processo de shot peening na taxa de propagação de trinca por fadiga na liga aeronáutica 2024 - T3." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/123234.
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000824425.pdf: 5119036 bytes, checksum: d2208b40c21a089b314a4455cfc48518 (MD5)Este trabalho tem por finalidade avaliar o efeito do processo de shot peening na taxa de propagação de uma trinca por fadiga já existente. O shot peening é um processo de trabalho a frio, que consiste no jateamento repetitivo com microesferas de aço, cerâmica ou vidro, na superfície de uma peça, produzindo encruamento e induzindo tensões residuais compressivas nas superfícies tratadas. Devido a isso, o shot peening tem-se mostrado um método bastante eficiente para dificultar o início e a propagação de uma trinca por fadiga a partir da superfície do material, melhorando a sua resistência à fadiga. Contudo, estudos de seu efeito sobre uma trinca já existente são pouco conhecidos. Corpos de prova do tipo CT, para a liga aeronáutica de alumínio 2024 - T3, foram inicialmente trincados por fadiga e, em seguida, submetidos ao processo de shot peening em ambos os lados. Após o tratamento, os ensaios foram reiniciados nas mesmas condições. Os ensaios foram realizados com amplitude constante em duas espessuras de corpos de prova e duas razões de carga, R, para analisar possíveis efeitos do estado de tensão na ponta da trinca nos resultados. Duas intensidades de shot peening foram utilizadas para cada valor de R ou espessura analisada. Também foram estudadas duas regiões de aplicação do processo de shot peening (atrás e em volta da ponta da trinca) em dois tamanhos de trincas. Curvas comparativas do comportamento da taxa de propagação de trincas por fadiga, mostrando a influência de cada um dos parâmetros descritos, são apresentadas, e suas diferenças, discutidas. Os resultados encontrados mostram que o processo de shot peening, quando realizado em um tamanho de trinca em pleno estágio II de propagação, apresenta maior influência quando aplicado atrás da ponta da trinca, com menor intensidade, em corpos de prova em estado ... (Resumo Completo, clicar acesso eletrônico abaixo)
This work focuses to evaluate the effect of the shot peening process in the propagation rate of a fatigue crack already existing. The shot peening is a cold working process, which consists of repetitive blasting with steel shot, ceramic or glass, the surface of a workpiece, producing hardening and inducing compressive residual stresses on the treated surfaces. Because of this, shot peening has proved a very efficient method for hindering the initiation and propagation of a fatigue crack from the surface of the material, improving its fatigue strength. However, studies of its effect on an already existing crack are little known. Specimens of type CT to the aeronautics aluminum alloy 2024 - T3, were initially cracked by fatigue and then subjected to shot peening process on both sides. After treatment, the tests were resumed under the same conditions. Tests were carried out with constant amplitude in two thicknesses of specimens and two load ratios, R, to analyze possible effects of stress state on the crack tip results. Two shot peening intensities were used for each R value or thicknesses analyzed, and were also studied two application regions of shot peening process (behind and around the crack tip) in two sizes of cracks. Comparative curves of the fatigue crack propagation rate, showing the influence of each of the parameters described are shown, and their differences discussed. The results show that the shot peening process, when performed in a crack size in full stage II propagation, has greater influence when applied behind the crack tip, with lower intensity, in the specimens in plane stress state and lower load ratio. For crack lower (close to the stage I of propagation), the shot peening process applied behind the crack tip induced delay in their propagation rate in all conditions studied. The delay effect on fatigue crack propagation rate ... (Complete abstract click electronic access below)
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Costa, Douglas Henrique da Silva. "Estudo do efeito do processo de shot peening na taxa de propagação de trinca por fadiga na liga aeronáutica 2024 - T3 /." Guaratinguetá, 2015. http://hdl.handle.net/11449/123234.
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Orientador: Marcelo Augusto Santos TorresBanca: Antonio Jorge Abdalla
Banca: Carlos Antonio Reis Pereira Baptista
Resumo: Este trabalho tem por finalidade avaliar o efeito do processo de shot peening na taxa de propagação de uma trinca por fadiga já existente. O shot peening é um processo de trabalho a frio, que consiste no jateamento repetitivo com microesferas de aço, cerâmica ou vidro, na superfície de uma peça, produzindo encruamento e induzindo tensões residuais compressivas nas superfícies tratadas. Devido a isso, o shot peening tem-se mostrado um método bastante eficiente para dificultar o início e a propagação de uma trinca por fadiga a partir da superfície do material, melhorando a sua resistência à fadiga. Contudo, estudos de seu efeito sobre uma trinca já existente são pouco conhecidos. Corpos de prova do tipo CT, para a liga aeronáutica de alumínio 2024 - T3, foram inicialmente trincados por fadiga e, em seguida, submetidos ao processo de shot peening em ambos os lados. Após o tratamento, os ensaios foram reiniciados nas mesmas condições. Os ensaios foram realizados com amplitude constante em duas espessuras de corpos de prova e duas razões de carga, R, para analisar possíveis efeitos do estado de tensão na ponta da trinca nos resultados. Duas intensidades de shot peening foram utilizadas para cada valor de R ou espessura analisada. Também foram estudadas duas regiões de aplicação do processo de shot peening (atrás e em volta da ponta da trinca) em dois tamanhos de trincas. Curvas comparativas do comportamento da taxa de propagação de trincas por fadiga, mostrando a influência de cada um dos parâmetros descritos, são apresentadas, e suas diferenças, discutidas. Os resultados encontrados mostram que o processo de shot peening, quando realizado em um tamanho de trinca em pleno estágio II de propagação, apresenta maior influência quando aplicado atrás da ponta da trinca, com menor intensidade, em corpos de prova em estado ... (Resumo Completo, clicar acesso eletrônico abaixo)
Abstract: This work focuses to evaluate the effect of the shot peening process in the propagation rate of a fatigue crack already existing. The shot peening is a cold working process, which consists of repetitive blasting with steel shot, ceramic or glass, the surface of a workpiece, producing hardening and inducing compressive residual stresses on the treated surfaces. Because of this, shot peening has proved a very efficient method for hindering the initiation and propagation of a fatigue crack from the surface of the material, improving its fatigue strength. However, studies of its effect on an already existing crack are little known. Specimens of type CT to the aeronautics aluminum alloy 2024 - T3, were initially cracked by fatigue and then subjected to shot peening process on both sides. After treatment, the tests were resumed under the same conditions. Tests were carried out with constant amplitude in two thicknesses of specimens and two load ratios, R, to analyze possible effects of stress state on the crack tip results. Two shot peening intensities were used for each R value or thicknesses analyzed, and were also studied two application regions of shot peening process (behind and around the crack tip) in two sizes of cracks. Comparative curves of the fatigue crack propagation rate, showing the influence of each of the parameters described are shown, and their differences discussed. The results show that the shot peening process, when performed in a crack size in full stage II propagation, has greater influence when applied behind the crack tip, with lower intensity, in the specimens in plane stress state and lower load ratio. For crack lower (close to the stage I of propagation), the shot peening process applied behind the crack tip induced delay in their propagation rate in all conditions studied. The delay effect on fatigue crack propagation rate ... (Complete abstract click electronic access below)
Mestre
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Pinto, Junior Carlos Carvalho Engler 1965. "Analise de retardo na propagação de trincas de fadiga em uma chapa de aluminio 2024-T3 submetida a carregamentos de amplitude variavel." [s.n.], 1989. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264893.
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Orientador: Ana Maria Martinez NazarDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Campinas
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Resumo: A maior parte das falhas de estruturas metálicas particularmente na indústria aeronáutica, é devido à ação de cargas cíclicas (fadiga), que podem provocar o surgimento e a propagação de trincas no material. Quando o espectro de cargas apresenta amplitudes variáveis, ocorrem efeitos de interação entre a "história dq carregamento" (sequência de aplicação das cargas) e a taxa de propagação da trinca. Dentre estes efeitos de interação, o mais importante é o retardo na propagação da trinca, que pode aumentar consideravelmente a vida útil da estrutura trincada. O objetivo principal deste trabalho é analisar e quantificar o retardo na propagação de trincas em uma chapa fina da liga de alumínio de alta resistência 2024- T3, comparando os modelos matemáticos existentes para representar este fenômeno. Foram realizados ensaios do tipo sequencial alto-baixo, para diferentes tamanhos dê trinca e relação de sobrecarga (Rsc = Kmaxa/ Kmaxb). Verificou-se experimentalmente que o retardo é proporcional à Rsc, e que o efeito do retardo permanece pelo menos até que a ponta da trinca atinja o fim da zona plástica induzi da pela carga alta. Uma comparação dos resultados experimentais com os modelos de Willemborg e Wheeler mostrou que estes não representam de maneira correta o comportamento da trinca. Foi desenvolvida uma expressão para corrigir o tamanho da zona plástica para condições intermediárias entre tensão plana e deformação plana. Com esta expressão corrigida, foi possível desenvolver um modelo simplificado, baseado na teoria das tensões de fechamento da trinca, que conseguiu representar muito bem o comportamento da trinca durante o retardo, principalmente para condições de tensão plana. Finalmente, foi constatado que a teoria das tensões de fechamento também é capaz de prever as condições de parada total no crescimento da trinca.
Abstract: The majority of failures in metallic structures, especially in the aeronautic industry, are due to cyclic loads (fatigue), which can nucleate and propagate cracks through the material. In variable amplitude loading, there are interaction effects between the loading history and the crack propagation rate. The most important of those effects is the retardation in the crack propagation, that may raise considerably the life of the cracked structure. The main objective or this research is to analyse and quantify the retardation of crack propagation in a thin plate of the high-resistance aluminum alloy 2024- T3, comparing the results obtained from the mathematical models proposed to account for the retardation effect. The specimens were tested under a high-Iow loading sequence, for different crack sizes and overload ratios (RoI = Kmaxh / Kmax,). It was verified that the retardation is proportional to Rol, and that the models of Willemborg and Wheller couldn't represent correctly the crack behaviour after the transition to the low level loads, because the retardation was observed at least until the crack tip reached the end of the plastic zone due to the high loads. It was proposed an expression to correct the plastic zone size for conditions between plane stress and plane strain. With that corrected expression, and based on crack closure theory, it was proposed a simplified model, that represent with good precision the crack behaviour during retardation, particularly for plane stress conditions. Finally, it was also verified that the crack closure theory allows the prediction of crack arrest conditions.
Mestrado
Mestre em Engenharia Mecânica
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Sofyan, Nofrijon Bin Imam Gale W. F. "Microstructure and mechanical properties of 2024-T3 and 7075-T6 aluminum alloys and austenitic stainless steel 304 after being exposed to hydrogen peroxide." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Materials_Engineering/Dissertation/Sofyan_Nofrijon_36.pdf.
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Nookala, RamaKrishna. "Mechanistic Study of Silane Assisted Rubber to Brass Bonding and the Effect of Alkaline Pre Treatment of Aluminum 2024 T3 on Silane Performance." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148065049.
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Le, Thi My Linh. "Simulation de l'effet du confinement sur l'endommagement d'un assemblage en alliage d'aluminium." Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS048.
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Pour les structures aéronautiques, les zones sensibles à la corrosion sont principalement celles où le plan de protection de la structure peut être mis en défaut, comme à l’intérieur des joints de recouvrement (dénommé «lap joint» en anglais). Les assemblages de tôles métalliques réalisés par recouvrement en utilisant, par exemple le rivetage, peuvent présenter des défauts de contact et donc il peut exister un interstice entre les deux parties de l’assemblage. En général cet interstice est isolé de l’environnement extérieur par un mastic. Mais il y a un risque de piégeage d’humidité plus ou moins concentrée en ions agressifs qui peut provoquer des endommagements ou aggraver ceux initiés sur des défauts des revêtements. Le premier objectif de cette thèse est de développer une méthodologie permettant de reproduire, de manière contrôlée et de façon la plus représentative de cas réels, la corrosion d’un alliage d’aluminium 2024-T3 constituant un joint de recouvrement afin d’effectuer des observations complétées par des mesures chimiques et électrochimiques. Le deuxième objectif est de tester l’application de modèles de transport réactif (en milieu confiné) pour voir s’il est possible de simuler les réponses (chimiques ou électrochimiques) mesurées expérimentalement et donc de prédire sur le long terme l’évolution d’un assemblageFor aircraft structures, corrosion sensitive areas are mainly those where the protection of the structure may suffer local breakdowns, as encountered inside lap joints. The assemblies of metal plates by overlapping (riveting) may present some defects in contact and consequently a gap can exist between the two parts of the assembly. Typically this gap is isolated from the outside environment by a sealant. But there is a risk of trapping of moisture more or less concentrated in aggressive ions which can induce corrosion or increase the damages initiated on coating defects. The first objective of this thesis is to develop a methodology to reproduce in a controlled manner and in the most representative way regarding actual cases, the corrosion of a lap joint made of aluminum alloy 2024- T3 plates, to perform not only observations but also chemical and electrochemical measurements. The second objective is to test the application of reactive transport models (in confined media) to check if it is possible to simulate the chemical or electrochemical changes recorded during experiments and thus to predict the long-term evolution of lap-joint in humid environment
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Martin, Castillo Morales. "Examining the effects of ultrasonic impact treatment as a severe plastic deformation process on the fatigue behaviour of 2024-T3 and T150-T651 aluminium alloys." Thesis, University of Sheffield, 2008. http://etheses.whiterose.ac.uk/6106/.
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Aluminium alloys are widely used in aerospace vehicles which are under cyclic loads through their operation. The loads may cause detrimental changes in material structure being more prone to crack initiation, starting a potential process of failure for the structure. In this research the effects of fatigue damage are assessed for two aluminium alloys, 2024-T3 and 7150-T561, after using a surface engineering method which uses the plastic deformation on the surface, like many others, to extend (or reduce) the fatigue life of materials.
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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.
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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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Ely, Marion. "Conversion chimique des surfaces d'alliages d'aluminium sans chrome hexavalent." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066663/document.
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Les couches de conversion actuellement utilisées dans l'industrie aéronautique, pour protéger le métal de la corrosion et favoriser l'adhérence de la peinture, contiennent du chrome hexavalent, composé toxique et cancérigène dont l'utilisation va prochainement être interdite par la réglementation européenne REACh. L'une des pistes envisagée pour remplacer ces couches chromatées est l'utilisation de couches de conversion TCP (Trivalent Chromium Protection). Ces travaux portent sur l'étude des couches de TCP et s'attachent à caractériser chaque étape du traitement de surface industriel, incluant les étapes de prétraitement et de post-traitement. Des techniques d'analyse de surface (XPS, ToF-SIMS, AFM, MEB et PM-IRRAS) ont été utilisées pour analyser la composition chimique et la morphologie de la surface après chaque étape du traitement. Cette étude a été réalisée sur un alliage d'aluminium AA 2024-T3, très utilisé en aéronautique pour ses propriétés mécanique, mais présentant une faible résistance à la corrosion. Les résultats obtenus ont notamment mis en évidence que la couche de TCP se forme sur toute la surface de l'alliage (composés intermétalliques et cavités), et ont permis de comprendre comment le post-traitement permet d'améliorer la résistance à la corrosion de la couche de TCP. Ces travaux s'intéressent également à des couches de conversion sans chrome, à base de zirconium, étudiées ici pour servir de point de départ au développement d'une conversion sans chrome qui respecterait les exigences de résistance à la corrosionConversion coatings are used in aerospace industry to protect the metal from corrosion and to promote paint adhesion. Currently, chromate conversion coatings are used, but chromate is toxic and carcinogenic and its use will be forbidden by the European REACh regulation. TCP (Trivalent Chromium Protection) conversion coatings, are considered as a promising alternative to replace chromate conversion coating. This work focuses on the characterisation of the TCP layer and considers each step of the industrial surface treatment, including pre-treatment and post-treatment steps. Surface analytical techniques (XPS, ToF-SIMS, AFM, SEM and PM-IRRAS) were used to analyse the chemical composition and morphology of the surface after each step in the process. This work was done on an aluminium alloy AA 2024-T3, commonly used in the aerospace industry for its good mechanical properties, but poorly resistant to corrosion. The results obtained demonstrate, among other things, that the TCP layer totally covers the surface (intermetallic compounds and cavities) and enable to understand how the post-treatment can improve the corrosion resistance of the TCP coating. This work also focuses on conversion coating based on zirconium, which are studied here to be used as a starting point to develop a new conversion coating without chromium, meeting the corrosion resistance requirement
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Gates, Nicholas R. "Fatigue Behavior under Multiaxial Stress States Including Notch Effects and Variable Amplitude Loading." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1469637495.
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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.
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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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Young, Paul S. "Modeling and Analysis for Atmospheric Galvanic Corrosion of Fasteners in Aluminum." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430416832.
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Lee, Michael Che-Chiang. "Pretreatments of Al-2024 T3 alloy for BTSE silane deposition." Thesis, 2002. http://hdl.handle.net/2429/14287.
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Work in this thesis studied different alkaline etching procedures performed on
Al-2024 alloy prior to deposition of bis-triethoxysilylethane (BTSE). X-ray photoelectron
spectroscopy and scanning electron microscopy were used to study the chemistry and
morphology of the surfaces formed after the various pretreatments and coatings have
been applied. The corrosion performance of these samples were assessed using
polarisation curve measurements and immersion testing. Sonicating tests were performed
to determine, semi-quantitatively, the adhesion of BTSE to Al-2024 panels after
application of the various pretreatments.
Alkaline etching of the coated and uncoated Al-2024 panels was performed using
10% NaOH in deionised water, varying the duration of the treatment from 1 minute to 10
minutes. It is shown on uncoated Al-2024 that longer etching times increase surface
roughness of the substrate, but also reduce corrosion resistance, cause copper enrichment
at the surface, and form loosely-bonded etching products which affect the subsequent
silane deposition steps.
BTSE solutions varying from 1% to 10% (v/v) BTSE were used to coat the
pretreated panels. It is found that BTSE-coated samples perform better than their
uncoated counterparts in corrosion testing, and that more-concentrated BTSE solutions
on identically prepared panels produce thicker coatings, with better passivation. It is also
found that, while increasing the alkaline etching time may lead to conditions where more
BTSE is deposited to the surface, this "enhanced" silane layer is not as securely-bonded
to the surface and will not aid in the passivation of the substrate.
Finally, the effects of the HNO₃ desmutting step were studied by varying the
treatment times that the Al-2024 panels received in 10% FINO₃ after 1 minute of alkaline
etching. It is found that for up to 30 minutes of treatment, FINO₃ is beneficial to silane
deposition as it removes the etching product created during the NaOH treatment, builds
up the oxide layer and creates more sites for the silane bonding. However, with longer
exposure, HNO₃ acts as a corrosion agent removing previously-built oxide layer which
reduces the amount of securely-bonded BTSE.
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Lo, Shih-Ming, and 羅世明. "Process Development of Friction Stir Clinching of Alcad 2024-T3 Aluminum Sheets." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/38362402963846173311.
Full textAbstract:
碩士國立中正大學
機械工程學系暨研究所
102
A novel friction stir spot clinching (FSSC) process which combines the conventional FSSW process and clinching process was proposed to join Alcad 2024-T3 Aluminum Sheets. The research works first investigated the effects of tool size and die size on the mechanical locking structure and shear strength of clinch joints. The processing parameters such as tool pin length, indentation depth, rotational speed, hold time, were then investigated to obtain appropriate processing parameters. The effects of tool geometry on the locking structure of clinch joints were studied as well. Finally, the mechanical performances of different locking structures in clinch joints, including the shear strength, opening strength, and fatigue life, were examined to verify the feasibility of the FSSC process.
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Yi, Han-Bang, and 易漢邦. "A Study of Trivalent Chromium Conversion Coatings on Aluminum Alloy 2024-T3." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/29232571116092772509.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
103
Aluminum alloy 2024-T3 has widely been used in the aircraft industry. To avoid an air crash caused by corrosion of the alloy, conversion coatings have commonly conducted on aluminum alloy 2024-T3. Hexavalent chromium conversion coatings provide excellent anti-corrosion properties; however, hexavalent chromium is a toxic element and harmful to species and environment. International directives have strictly banned the use of hexavalent chromium. Therefore, many efforts have been made to find the process alternative to hexavalent chromium conversion process. Trivalent chromium conversion coating is a potential alternative process to hexavalent chromium conversion coating. However, the oxidizing capability of trivalent chromium is inferior to hexavalent chromium. Moreover, trivalent chromium conversion coating does not have self-healing capability. Modifications of the processing procedure are thus essential to improve the anti-corrosion properties of trivalent chromium conversion coating. The trivalent chromium conversion solution we now use in Taiwan is imported from foreign manufacturers and the modifications we can make are limited by aerospace specifications. Under that premise, this study is to understand the effect of two different acidic pretreatments, nitric acid and Deoxidizer 6, on the microstructure and properties of the subsequent trivalent chromium conversion coating on aluminum alloy 2024-T3. The results show that the coating treated with nitric acid pretreatment performs better in potentiodynamic polarization test and are able to pass 168-hr of the salt spray test. Pits attacked by F ions become larger and then coalescence with each other, resulting in a rough surface after pretreatment in Deoxidizer 6. The uneven surface may also influence the uniformity of the trivalent chromium coating. However, there are only a few pits on the surface pretreated in nitric acid and the surface seems smoother than that pretreated in Deoxidizer 6. Cross-sectional characterization reveals the presence of trivalent chromium conversion coating on aluminum alloy 2024-T3 after immersion in Metalast TCP-HF regardless of the acidic pretreatments. The trivalent chromium conversion coating on aluminum alloy 2024-T3 pretreated in nitric acid is denser and thicker compared to that on aluminum alloy 2024-T3 pretreated in Deoxidizer 6. A two-layered structure is clearly observed, where Cr(III) and Zr content in the outer part of the coating is higher than that in the inner part. On the contrary, the inner part of the coating is rich in Al. The trivalent chromium conversion coating on aluminum alloy 2024-T3 is composed of oxide and hydroxide of Cr(III), Zr, and Al, as revealed by XPS. Due to the presence of chromate ions in Deoxidizer 6, there is already a thin film containing Cr(III) on the surface after the acidic pretreatment. This thin film serving as a passivation layer deteriorates the reactivity during the following TCP. With respect to the uniformity of the coating and reactivity of conversion reaction, the pretreatment in nitric acid is more suitable for the trivalent chromium conversion process using the Metalast TCP-HF solution.
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Chien-HsiungWang and 王健雄. "Effect of Corrosion on the Fatigue Behavior of 2024-T3 Aluminum Alloy." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/10456738190327065849.
Full textAbstract:
碩士國立成功大學
航空太空工程學系專班
98
In this study, the 2024-T3 aluminum alloy was used as base material. By using alternative immersion corrosion process with an artificial corrosive environment in laboratory, 2024-T3 aluminum alloy specimens were subjected to continual immersion-dry process in 3.5% sodium chloride solution for 7, 21, and 42 days, respectively. After the corrosion process, the specimens were then subjected to fatigue test at different stress levels and S-N curves of material under different corrosion level were obtained. In addition, through the use of Scanning Electronic Microscope, the depth and dimension of pitting on the fracture surface of specimens were observed. The experiment results show that the fatigue lives of specimens reduce as the exposure time increases. For example, at the stress level of 25 ksi, fatigue lives of specimens subjected to immersion-dry process for 42 days reduce approximately by 35% and 16%, respectively, as compared to those subjected to processes for 7 and 21 days. Furthermore, fatigue life of material was affected by the combined effects of pit depth, leading edge shape of pit, loss of cross-section, multiple fatigue cracks growth and stress.
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Su, Zheng-Ming, and 蘇政明. "Fatigue Analyses for Swept Friction Stir Spot Welds on Alclad 2024-T3 Aluminum Sheets." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/32789261495511115247.
Full textAbstract:
博士國立中正大學
機械工程學系暨研究所
102
Fracture and fatigue behaviors of swept friction stir spot welds (Swept-FSSWs) in lap-shear and cross-tension specimens of Alclad 2024-T3 aluminum sheets were first investigated by experimental approaches in this research. The Swept-FSSWs were made by a welding tool with a triangular probe and aluminum sheets with 1.6 mm thickness. Optical and scanning electron micrographs of the welds before and after failure under quasi-static and cyclic loading conditions were examined. Experimental results indicated that lap-shear specimens have three failure modes while cross-tension specimens have two failure modes. Based on the paths of the dominant fatigue cracks, two Fatigue crack growth models, including the global and local stress intensity factors for kinked cracks combined with the Paris law for crack propagation, were developed to estimate the fatigue lives of Swept-FSSWs. The fatigue life estimations based on the models agreed well with the experimental results. In addition, the equivalent local stress intensity factor from finite kinked cracks was taken as a factor to collapse fatigue data of Swept-FSSWs in lap-shear and cross-tension specimens. The regression curve of the collapsed data could be used for fatigue life estimations of Swept-FSSWs under general loading conditions.
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Pan, Chun-Ting, and 潘俊廷. "Effect of Acidic Pretreatments on Trivalent Chromium Conversion Coating on Aluminum Alloy 2024-T3." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/596vf6.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
105
Aluminum alloy 2024-T3 has widely been utilized in the aircraft industry because of the high mechanism strength and low-weight. Adding alloy elements into aluminum substrate improve the mechanism strength but reduce the corrosion resistance. To improve corrosion resistance, conversion coating has been conducted on aluminum alloy 2024-T3. Hexavalent chromium conversion coating once is a choice of conversion coating; However, Hexavalent chromium is a toxic substance and harm both human and environment. Therefore, substitutions are necessary. Trivalent chromium conversion coating is a potential substitution for hexavalent chromium; However, Trivalent chromium conversion isn’t as good as Hexavalent chromium in corrosion resistance and doesn’t exhibit self-healing behavior. Modification of the processing procedure is hence necessary to improve the anti-corrosion property of trivalent chromium conversion coating. There are two series of precipitates in aluminum alloy 2024-T3: Al-Cu-Mg and Al-Cu-Fe-Mn, former is more active than matrix and the latter is more noble than matrix. After the acidic pretreatment of nitric acid, Al-Cu-Mg precipitates dealloy. The extent of dealloying is more obvious when the processing time goes. Al-Cu-Fe-Mn precipitates have little influence during the procedure. Both type of precipitates are eroded severely especially Al-Cu-Mg precipitates during acidic pretreatment of Deoxidizer 6, and grew a thin layer of Cr oxides on the surface. The specimens treated by nitric acid exhibit better corrosion resistance than those treated by Deoxidizer 6 in salt spray test. Dome-like corrosion product can be observe on the specimens treated by both parameters but the large scale corrosion only can be observed in specimens treated by Deoxidizer 6.
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Matos, Paulo Fernando Pinto de. "The influence of residual stresses on the fatigue behaviour of 2024-T3 Al specimens." Dissertação, 2003. http://hdl.handle.net/10216/12149.
Full textAbstract:
Dissertação apresentada para obtenção do grau de Mestre em Engenharia Mecânica, na Faculdade de Engenharia da Universidade do Porto, sob a orientação dos Professores Paulo Manuel Salgado Tavares de Castro e Artur Portela
48
Susac, Darija. "Surface science studies of organosilane and zinc phosphate coatings on 2024-T3 aluminum alloy." Thesis, 2003. http://hdl.handle.net/2429/16104.
Full textAbstract:
The effects of 2024-T3 alloy microstructure on the formation of organosilane and zinc phosphate (ZPO) coatings have been studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) , energy dispersive X-ray (EDX ) spectroscopy and scanning Auger microscopy (SAM). Some studies of corrosion protection were also made using electrochemical polarization measurements, especially for comparing different post-treatment rinses applied to the ZPO coatings. This thesis describes new information for the different chemistries occurring at microregions of 2024-A1 alloy, especially those associated with intermetallic compounds (secondphase particles) of compositions Al-Cu-Mg and Al-Cu-Fe-Mn. These particles have been shown to strongly affect initiation of the ZPO coatings. Coating crystallites start to form at Al-Cu-Mg particles, while the coverage on the Al-Cu-Fe-Mn particles is more amorphous. During the etching stage o f the coating process, the natures of the Al-Cu-Mg particles appear to change from anodic to cathodic character, and this helps drive the precipitation of ZPO crystals. Additionally, a Cu enrichment is found at the interface between the Al-Cu-Mg particles and the ZPO coating. After completion, the coating thickness is least on the matrix regions closest to the Al-Cu-Mg particles, where the competition between substrate etching and ZPO deposition is strongest. A lowering in the pH of the coating solution results in thinner and more amorphous ZPO coatings, and a greater Cu enrichment. The adsorption of bis-l,2-(triethoxysilyl)ethane (BTSE) silane is also strongly affected by the distribution o f second-phase particles and by the amount of oxide at the 2024-A1 alloy surface. For a mechanically-polished sample, BTSE adsorbs on the matrix regions away from the particles, and on the particles themselves, but less adsorbs near the particle-matrix interface areas. For an air-oxidized sample, the amount o f adsorbed BTSE increases markedly, but with a high degree of non-uniformity. It is postulated that the BTSE deposition depends on the precise natures of oxide layer formed at the various micro-areas, and on the competition between silane deposition and oxide etching. In contrast, y-aminopropyltriethoxysilane (y-APS) forms a film of relatively even thickness over a large sample area, apparently due to the formation of hydrogen bonds through the amino groups.Science, Faculty of
Chemistry, Department of
Graduate
49
Matos, Paulo Fernando Pinto de. "The influence of residual stresses on the fatigue behaviour of 2024-T3 Al specimens." Master's thesis, 2003. http://hdl.handle.net/10216/12149.
Full textAbstract:
Dissertação apresentada para obtenção do grau de Mestre em Engenharia Mecânica, na Faculdade de Engenharia da Universidade do Porto, sob a orientação dos Professores Paulo Manuel Salgado Tavares de Castro e Artur Portela
50
Hsu, Hsiao-Hung, and 許曉弘. "EndoFEM Studies on Mode I Crack Growth Mechanical Behavior of Al 2024-T3 CT Specimen." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/17006802672350624280.
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