Dissertations / Theses on the topic 'Seawater corrosion'
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Speyer, Andrew James. "Wear/corrosion sensing in flowing seawater." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269992.
Full textSingh, Harshmeet. "The corrosion behaviour of aluminium alloy B206 in seawater." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/56551.
Full textApplied Science, Faculty of
Materials Engineering, Department of
Graduate
Thistlethwaite, Christopher. "Behaviour of massive reinforced concrete sections in seawater." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/4819cd1e-a5ce-48c2-a982-874196b3e8d9.
Full textMasters, G. L. "Crevice corrosion of austenitic and duplex stainless steels in seawater." Thesis, Cranfield University, 1994. http://dspace.lib.cranfield.ac.uk/handle/1826/11288.
Full textPuget, Yannick. "Failure mechanism of polyurethane coated steel subjected to erosion-corrosion." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287320.
Full textBaker, Devon Scott. "Understanding the Corrosion of Low-Voltage Al-Ga Anodes." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/53835.
Full textMaster of Science
Takeuchi, M. "Fretting and fatigue of a roping steel in seawater." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384690.
Full textCoimbatore, Dhandayuth Venkatesh. "Cerium chloride inhibition for high strength low alloy steel exposed to sulphide polluted seawater." University of Western Australia. School of Mechanical Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0134.
Full textSneddon, A. D. "Macrofouling and corrosion of steels and copper-nickel alloys in seawater." Thesis, Robert Gordon University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378071.
Full textSmallwood, Russell. "Fretting fatigue of steel roping wire in seawater." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328387.
Full textGujarathi, Kedar Kanayalal. "Corrosion of aluminum alloy 2024 belonging to the 1930s in seawater environment." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3002.
Full textCarvalho, Maria Leonor. "Corrosion of copper alloys in natural seawater : effects of hydrodynamics and pH." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066304/document.
Full textThis thesis was carried out in the frame of the BIOCOR ITN European project, in close collaboration with the industrial partner RSE S.p.A. (Italy). Copper alloys commonly used in cooling systems of power plants may be affected by biocorrosion induced by biofilm formation. The main objective of this work was to study the corrosion behavior of 70Cu-30Ni alloy and aluminum brass in seawater environments, under real industrial conditions (field experiments) and in laboratory. The influence of different parameters, such as the solution (filtered natural seawater (FNSW) vs artificial seawater (ASW)), the concentration of biomolecules (biomolecules naturally present in seawater vs a model protein, the bovine serum albumin (BSA)), hydrodynamics (static conditions, under flow and stirring, rotating ring electrode (RRE)) and pH (8.0, 6.0 and 3.7), was evaluated. In field, the overall corrosion behavior and antifouling treatments were monitored using electrochemical (corrosion potential Ecorr vs time, LPR), gravimetric (weight losses) and genetic techniques. In lab, electrochemical measurements (Ecorr vs time, polarization curves, EIS), performed during the very first steps of oxide layers formation (1 h immersion time), were combined to surface analysis by XPS and ToF-SIMS. From field experiments, microbiological and molecular analysis of biofilms formed on both copper alloys in natural seawater indicates the presence of Marinobacter, Alteromonas and Pseudomonas bacterial species. From lab experiments, models are proposed to analyze impedance data obtained at Ecorr. In the case of 70Cu-30Ni, the HF loop illustrates mainly the anodic charge transfer (diameter equal to Rta); whereas the LF loop is related to the anodic mass transport and partial blocking effect by CuCl. In the case of Al brass, the single experimental loop illustrates both anodic charge transfer and anodic mass transport. Similar electrochemical behavior and surface chemical composition of 70Cu-30Ni alloy are obtained in static ASW and FNSW, due to the low biomolecule concentration in FNSW. Compared to 70Cu-30Ni in static ASW without biomolecules, for which a thick duplex oxide layer (outer redeposited Cu2O layer and inner oxidized nickel layer) is shown, the presence of BSA leads to a mixed Cu and Ni oxide layer with a lower thickness; the results also show a slow-down of the anodic reaction and a small corrosion inhibition effect in the presence of BSA. Under flow and stirring, a very thin mixed Cu and Ni oxide layer is obtained. For both alloys in FNSW, the corrosion current icorr estimated from Rta is independent of the rotation speed of the RRE, due to compensated potential and mass transport effects. For 70Cu-30Ni in static FNSW, the anodic reaction is slown down at acidic pH (kinetic effect). For Al brass, there is a corrosion inhibition effect at acidic pH, and the more acidic the pH, the slower the anodic reaction. In the case of 70Cu-30Ni alloy, the oxide layer thickness increases with decreasing pH, whereas for Al brass it is independent of the pH. The chemical composition of the oxide layer seems to have an effect on the amount of adsorbed proteins and the calculated organic layer equivalent thickness is very low (few Å for 70Cu-30Ni and 1 Å for Al brass)
Ismail, Azzura. "Seawater as a hydraulic fluid : corrosion mechanisms and rates of engineering materials." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7320/.
Full textTan, KengSoong. "Electrochemical analysis of the erosion corrosion of HVOF aluminium bronze coatings." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274707.
Full text徐立沖 and Lichong Xu. "Anaerobic corrosion of mild steel in seawater induced by sulfate-reducing bacteria (SRB)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31242546.
Full textTodoroff, Peter Kent. "Effect of Turbulence on the Passive Film Growth and Associated Durability of Aluminum Alloys in Simulated Seawater." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83770.
Full textMaster of Science
Taylor, Ryan Chandler. "Effect of a Simulated Butterfly Valve on the Erosion-Corrosion Rate of Nickel Aluminum Bronze Alloys in Highly Turbulent Seawater." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83818.
Full textMaster of Science
Xu, Lichong. "Anaerobic corrosion of mild steel in seawater induced by sulfate-reducing bacteria (SRB)." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk:8888/cgi-bin/hkuto%5Ftoc%5Fpdf?B2327315x.
Full textWu, Siu-kin. "Corrosion and fouling in heat exchangers cooled by sea water from Hong Kong harbour /." Hong Kong : University of Hong Kong, 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12335472.
Full text胡少堅 and Siu-kin Wu. "Corrosion and fouling in heat exchangers cooled by sea water from HongKong harbour." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31208010.
Full textDupuis, Jennifer. "Investigation d’alliages à base de titane de types béta-métastables pour applications marines : cas particulier d’un winch innovant." Thesis, Rennes, INSA, 2014. http://www.theses.fr/2014ISAR0028/document.
Full textTitanium alloys are used in numerous fields as aerospace industry, automotive industry, off-shore industry, and, in several applications such as medical and marine applications. This is due to their good properties like high mechanical strength, low density and excellent corrosion resistance. In order to be used for an innovating winch and so in a marine environment, we have chosen to study three β-metastable titanium alloys which are Ti-6.8Mo-4.5Fe-1.5Al, Ti-15Mo-2.7Nb-3Al-0.2Si and Ti-5Al-5Mo-5V-3Cr. In marine environment, materials are exposed to tough conditions which can generate their destruction. Several modes of degradation exist. It is so interesting to evaluate the corrosion resistance of these alloys and to search their best corrosion protection. So, the heart of the study is to select titanium alloys to meet the specifications of the innovating winch. At first, we defined thermomechanical treatments for those titanium alloys and then these materials were characterized to know their mechanical and metallurgical properties. These tests allowed us to have a well knowledge of mechanical properties of these alloys and to choose which alloys can be employed in a winch. Then, galvanic corrosion tests were made in nitric acid, sodium chloride and sodium hydroxide. We measured potential differences between our treated titanium alloys and other materials which may be used in a winch such as stainless steels, aluminum alloys and leaded brass. Then, in order to evaluate the behavior of the passive film in marine environment of titanium alloys, electrochemical corrosion tests were conducted using a three-electrode method in sodium chloride and natural seawater electrolytes. So, free potential and cyclic voltammetry measurements were conducted. The flaw of titanium alloys is their low friction coefficient. So in order to improve the coefficient of friction of titanium alloys it is useful to do a surface treatment. In this study, a gaseous nitriding thermochemical treatment was done for the most recent developed alloy among the three studied nuances, which is Ti-5Al-5Mo-5V-3Cr. Then this treated alloy was characterized too similarly to the three thermomechanical treated titanium alloys. All of tests we led allowed us to know which titanium alloys with which thermomechanical and surface treatments may be used for the innovating winch
Howell, William R. N. "An analysis of possible microbiologically influenced crevice corrosion of 316 stainless steel in a seawater environment." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/7939.
Full textHowell, William R. N. (Robert Newton). "An analysis of possible microbiologically influenced crevice corrosion of 316 stainless steel in a seawater environment." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/39622.
Full textMachuca, Suarez Laura Lizeth. "Microbiologically influenced corrosion of common alloys used for subsea applications." Thesis, Curtin University, 2012. http://hdl.handle.net/20.500.11937/258.
Full textVenkatesan, R. "Studies On Corrosion Of Some Structural Materials In Deep Sea Environment." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/189.
Full textVenkatesan, R. "Studies On Corrosion Of Some Structural Materials In Deep Sea Environment." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/189.
Full textNæss, Monika. "EFFECT OF MICROSTRUCTURE AND SURFACE FINISH ON LOCALIZED CORROSION PERFORMANCE OF SUPER DUPLEX STAINLESS STEEL IN SEAWATER." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produksjons- og kvalitetsteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25741.
Full textMcKinnon, John Motley. "Corrosion Damage Evolution of a Unidirectional Pit." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1463754286.
Full textChicuba, Pedro Claudio Francisco. "Assessment of the corrosion behaviour of alloys 825 and 625 in stagnant seawater-effect of temperature and welding." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27392.
Full textMcGovern, Scott. "The development of embedded sensors to assess the fatigue response of adhesive joints in marine environments." Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080911.154008/index.html.
Full textStipaničev, Marko. "Improved decision support within biocorrosion management for Oil and Gas water injection systems." Phd thesis, Toulouse, INPT, 2013. http://oatao.univ-toulouse.fr/10304/1/stipanicev.pdf.
Full textMÁRQUEZ, Marcy Viviana Chiquillo. "Avaliação da resistência à corrosão do aço carbono ASTM 572 Gr50 exposto a óleo cru, água do mar e misturas de óleo/água do mar em condições estáticas e dinâmicas." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18603.
Full textMade available in DSpace on 2017-04-19T19:20:06Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação completa (FINAL).pdf: 5768431 bytes, checksum: 342e336553ff7aabb5d24cb8e9437063 (MD5) Previous issue date: 2016-11-17
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Nas diversas etapas processuais da indústria de petróleo – extração, recuperação, armazenamento, transporte e refino, os materiais metálicos são expostos a fluidos corrosivos e solicitações mecânicas. Na etapa de armazenamento, em tanques de petróleo, é possível evidenciar a presença de duas fases, uma oleosa e outra aquosa, que de forma isolada ou associada podem influenciar no processo corrosivo. No transporte de petróleo, apresenta-se o efeito de corrosão-erosão (C-E) gerado pela presença de sais, gases e partículas sólidas que prejudicam a integridade dos equipamentos. Este trabalho teve como objetivo avaliar o comportamento do aço ASTM 572 Gr50 exposto a óleo cru, água do mar e misturas desses fluidos em diferentes proporções; sob condições estáticas simulando tanques de armazenamento e dinâmicas, visando simular transporte dos fluidos. Foram realizados testes de imersão do aço em diferentes fluidos corrosivos (óleo cru, água do mar, misturas de óleo e água do mar nas proporções de 20 e 50 % em volume de água do mar), ao longo de 60 dias em condições estáticas e dinâmicas. O processo corrosivo do material exposto aos diferentes meios foi analisado através de ensaios de perda de massa, análises eletroquímicas de potencial de circuito aberto (PCA), polarização potenciodinâmica e espectroscopia de impedância eletroquímica (EIE). A morfologia da corrosão foi avaliada através de microscopia eletrônica de microscopia óptica (MO) e varredura (MEV). Testes de microdureza Vickers e análises microestruturais foram realizados para analisar a ocorrência de mudanças nas propriedades mecânicas dos aços. Os resultados evidenciaram a influência do teor de água do mar no processo corrosivo, onde foram observados maiores valores de taxa de corrosão para os sistemas contendo maior proporção de água do mar. O mecanismo de C-E, observado nos sistemas dinâmicos mostrou ser mais agressivo que o processo de corrosão isoladamente (sistemas estáticos) o que foi observado por meio dos maiores valores de taxa de corrosão e também pelas morfologias de processo de deterioração da superfície vista por MO e MEV, onde cavidades de maior longitude e pites internos foram observados para os sistema sujeitos ao processo de C-E. Não foram observadas mudanças significativas na microestrutura do material após exposição às condições de fluido estudadas. Os resultados de MEV mostraram a presença de corrosão localizada em todos os sistemas, inclusive para os sistemas contendo apenas óleo cru, que apresentou baixa taxa de corrosão. Os ensaios eletroquímicos de PCA, polarização e EIE realizados com os eletrólitos advindos dos ensaios de imersão (fase aquosa) mostraram que o contato entre fluidos distintos (óleo e água do mar) sob condições de agitação, promove uma intensa troca composicional entre os meios, aumentando a agressividade e modificando a interação metal/meio. O eletrólito proveniente do sistema dinâmico contendo mistura de óleo e água do mar (50%) foi o que se mostrou mais agressivo, visto que no ensaio de polarização linear apresentou o maior valor de densidade de corrente anódica.
In the various procedural stages of the oil industry - extraction, recovery, storage, transportation and refining, metal materials are exposed to corrosive fluids and mechanical stresses. In oil tanks of the storage step, it is possible to demonstrate the presence of two phases, an oily and other aqueous, which isolated or associated, can influence the corrosion process. In the oil transport the corrosion-erosion (C-E) effect is present and it is generated by the presence of salts, gases and solid particles that can influence the integrity of the equipment. This study aimed to evaluate the behavior of ASTM 572 GR50 steel exposed to crude oil, sea water and mixtures of these fluids in different proportions; under static conditions simulating storage tanks and dynamic conditions, aiming to simulate fluid transport. Immersion tests were performed in different corrosive fluids (crude oil, seawater, oil mixtures and sea water in the proportions of 20 to 50% by seawater volume) for 60 days, under static conditions and dynamics. The corrosive process of material exposed to different media was analyzed by mass loss tests and electrochemical analysis of open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The morphology of corrosion was assessed by microscopy optical (OM) and scanning electron microscopy (SEM). Vickers microhardness testing and microstructure analysis were performed to examine the changes occurring in the mechanical properties of steels. The results showed the influence of the seawater content in the corrosion process, in which were observed higher corrosion rate values for the systems containing higher proportion of seawater. The C-E mechanism, seen in dynamical systems proved to be more aggressive than corrosion process isolated (static systems) which was observed by means of higher corrosion rate values and also by the morphologies of the surface deterioration process seen by OM and SEM, where the greater length and internal cavities pits were observed for the system subject to the C-E process; There were not significant changes in the microstructure of the material after exposure to conditions fluid studied. SEM results showed the presence of localized corrosion on all systems, including systems containing only crude oil, which showed low corrosion rate. Electrochemical test OCP, polarization and EIS conducted with electrolytes arising from immersion tests (aqueous phase), showed that the contact between different fluids (oil and seawater) under agitation conditions, promotes an intense exchange compositional between the fluids, increasing the aggressiveness and modifying the metal/media interaction. The electrolyte from the dynamic system containing a mixture of oil and seawater (50%) was the more aggressive electrolyte, as can be seen in the linear polarization that showed the highest value of anodic current density.
Costa, Jeremias de Freitas. "Avaliação de aminoácidos como inibidores de corrosão para cobre em meio de água do mar artificial." Universidade do Estado do Rio de Janeiro, 2013. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8914.
Full textCorrosion inhibitors are substances that, when added to an aggressive medium reduce or prevent the oxidation reaction of a metal with such medium and / or the reduction reactions of specimens present in the medium. For inhibiting the corrosion of copper and copper alloys in acidic or neutral media, the most widely used inhibitor is benzotriazole (BTAH), which forms complexes with the Cu (I) and Cu (II) ions on the metal surface, decreasing the corrosive process. The concern for environmental preservation and the toxicity of corrosion inhibitors have been discussed in the literature. Several studies havebeen intensified using amino acids as a proposal to replace the BTAH, which is considered toxic. Among the amino acids studied, two presented sulfur in their molecules (cysteine and methionine) and another without heteroatom in the side chair (glycine). The concentrations ranged from 10-2 to 10-4mol/L and the pH of the solution variedbetween 7,2 and 8,4. Gravimetric measurements (total immersion tests) and electrochemical techniques, such as potentiodynamic polarization and electrochemical impedance spectroscopy, were performed. The morphological characterization of the substrate surface after the immersion tests (743 hours) was made by means of scanning electron microscopy (SEM), X-rays spectroscopy energy dispersive (EDS or EDX) and X-rays diffraction (XRD ).This effect was probably due to the increased concentration of molecules adsorbed on the metal surface. Although the results with amino acids were always lower than those obtained in the presence of BTAH, similar behaviorsas a function of the amino acid concentration could be observed for the Nyquist diagrams. However, except for the results observed for the cysteine medium containing 10-2mol/L, all the inhibition efficiencies of the media containing amino acids, obtained by total immersion tests, were negative, showing that exposure time may also be relevant to the performance of these inhibitors. Among all amino acids tested, the medium containing glycine showed the worst corrosion performance, accelerating the process of anodic dissolution of copper. This result may be related to the pH range of tested solutions and to the solubility of the copper complexes formed with amino acids, showing that an optimal range of pH must also be provided to enhance the action of these amino acids as corrosion inhibitors
Egtvedt, Solveig. "Thermally Sprayed Aluminum (TSA) with Cathodic Protection as Corrosion Protection for Steel in Natural Seawater : Characterization of Properties on TSA and Calcareous Deposit." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16340.
Full textNehybka, Josef. "Příprava historických pojiv s vysokou odolností proto okolním vlivům." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401936.
Full textKweon, Young-Gak. "Influence de divers paramètres sur la fissuration par fatigue d'aciers de construction dans l'eau de mer sous protection cathodique." Châtenay-Malabry, Ecole centrale de Paris, 1986. http://www.theses.fr/1986ECAP0010.
Full textItoh, Yoshito, Yasuo Kitane, Mikihito Hirohata, Junya Takemi, 義人 伊藤, 安雄 北根, 幹人 廣畑, and 潤也 竹見. "海水中環境を模擬した腐食促進実験による鋼溶接部の腐食劣化特性に関する基礎的研究." 土木学会, 2013. http://hdl.handle.net/2237/18850.
Full textZanibellato, Alaric. "Synthèse et études physico-chimiques d’un agglomérat calcomagnésien formé sur acier en milieu marin : un éco-matériau pour la protection du littoral." Thesis, La Rochelle, 2016. http://www.theses.fr/2016LAROS005/document.
Full textA new method, based on an innovative adaptation of cathodic protection principle of metal structures in marine environment, is to promote the precipitation of a calcareous agglomerate several centimeters thick. In the presence of sand and shells, this cluster could stabilize coastal areas being eroded or improve anchorage of breakwater riprap. The objective of this work is to study and understand the reaction mechanisms allowing to create a voluminous calcareous deposit away from the cathode and to optimize deposition time as well as its mechanical properties. First, it was shown in this work that the electrolytic medium could affect the growth of the deposit, with a possible inhibition of formation of calcium carbonate fot the low potential. The influence of corrosion products in the cathodic protection mechanism was also highlighted through polarizations performed in NaCl, artificial and natural sea water. Second, one month test with impressed current were conducted from laboratory to natural site, in order to get closer of real conditions. Current density and hydrodynamic conditions are key factors closely bonded to each other, affecting the mass and composition of the Ca/Mg ratio. This work has also helped to highlight the influence of the polarization time on the composition, with stable growth kinetics but a composition’s evolution after 15, 30 and 60 days. This internal variation of the Ca/Mg ratio attributed to a process of « dissolution/precipitation » is pH dependent and the distribution of these elements within the deposit could play a major role in the evolution of the mechanical strength of deposit over time
Al, Bacha Serge. "Générateur d’Hydrogène « vert » pour mobilité légère ou de courte distance Hydrogen generation via hydrolysis of ball milled WE43 magnesium waste Hydrogen generation from ball milled Mg alloy waste by hydrolysis reaction Effect of ball milling strategy (milling device for scaling-up) on the hydrolysis performance of Mg alloy waste Effect of ball milling in presence of additives (Graphite, AlCl3, MgCl2 and NaCl) on the hydrolysis performances of Mg17Al12 Corrosion of pure and milled Mg17Al12 in “model” seawater solution Mechanism of hydrogen formation during the corrosion of Mg17Al12 Hydrolysis properties, corrosion behavior and microhardness of AZ91 "model" alloys SECM investigation of galvanic coupling between Mg and Mg17Al12 in AZ alloys Valorization of AZ91 by the hydrolysis reaction for hydrogen production (Electrochemical approach) Clean hydrogen production by the hydrolysis of Magnesium-based material: effect of the hydrolysis solution." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0312.
Full textThe hydrolysis of magnesium alloys wastes in seawater (i.e. 3.5 wt.% of NaCl aqueous solution) is a new approach which allows both in-situ hydrogen production and the valorization of a priori non-recyclable wastes. The objective of this research work is to optimize the reactivity of magnesium-based wastes by ball milling with additives. Therefore, we investigated the effects of the main milling parameters (e.g. milling atmosphere, milling rotation speed, order of the addition of additives) on the reactivity of WE43 alloys and Mg – Al alloys wastes. A « scale-up » of the materials treatment process was conducted to explore the possibility of industrializing the process. In addition, we have shown that milling under argon is more advantageous than under hydrogen.Mg – Al alloys (more precisely AZ91) are the most widely used. In these alloys, Al forms with Mg the intermetallic Mg17Al12. To better understand the mechanism of hydrogen production from these binary Mg – Al alloys (Mg + Mg17Al12), evaluating the behavior of each of their constituents and their interactions is essential. In this regard, the chemical (i.e. hydrolysis) and electrochemical (i.e. corrosion) aspects of the reaction of Mg17Al12 with the model seawater solution and the effect of milling in the presence of additives (e.g. graphite, NaCl, MgCl2 and AlCl3) were studied. The evolution of the surface chemistry during polarization tests has proven experimentally (by Raman spectroscopy), for the first time, the formation of reaction intermediate and has allowed us to propose a mechanism of H2 formation.The interaction between Mg and Mg17Al12 was explored by comparing the properties of model materials of « AZ91 » (Mg + Mg17Al12). Using scanning electrochemical microscopy, the effect of galvanic coupling was studied at the interface of the two components of the material. In view of these studies, the contribution of Mg17Al12 in the corrosion of AZ91 alloys was clarified. The intermetallic is corrosion resistant and accelerates the corrosion of Mg due to galvanic coupling. The various milling strategies adopted in this work were compared by applying them to a commercial AZ91 alloy. Mechanical treated materials with graphite and AlCl3 showed the highest hydrolysis performances.Finally, we semi-quantitatively evaluated the purity of H2 (the composition of the gas mixture and its humidity) produced. The impact of few experimental conditions (e.g. composition of the solution, temperature, ratio of the mass of powder to the volume of solution) is reported. Thus, it has been shown that an Mg hydrolysis reactor operating at room temperature with seawater produces « clean » hydrogen in-situ and can be considered as a « green » hydrogen on demand generator
Auger, Fernand. "Altération des roches sous influence marine, dégradation des pierres en oeuvre, simulation accélérée en laboratoire." Poitiers, 1987. http://www.theses.fr/1987POIT2018.
Full textTchalla, Tatiana Siwavi. "Durabilité d'assemblages métal/élastomère en milieu marin." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0121/document.
Full textIn some industrial applications, bonding rubber coatings to metallic pipelines is a suitable solution to protect them from marine corrosion. This study deals with the long term behavior of such metallic coated pipelines in a marine environment. Two different approaches have been developed. The first focuses on degradation data of pipelines used for around thirty years in normal service conditions. As these bonded assemblies are different in terms of material formulations, manufacturing processes and aging conditions, statistical tools were used to identify homogeneous groups with identical aging mechanisms. Also, based on these results, the main degradation mechanisms of the rubber coating were established. The second approach focused on pipelines used currently in renovation operations. An experimental methodology was developed in the laboratory to accelerate aging processes. The bulk materials, surfaces and interfaces were characterized physically, chemically and mechanically before and after natural sea water ageing. This enabled an understanding of the mechanisms and kinetics governing adhesion and degradation to be developed. It also allowed the influence of sea water aging on the failure strength of the assembly of interest to be investigated
Wang, Xiang. "Long-term under-deposit corrosion of carbon steel pipes in seawater environment." Thesis, 2017. http://hdl.handle.net/1959.13/1335468.
Full textWater injection is the most commonly used method to increase the yield from oil and gas reservoirs. Seawater is typically the most convenient water source, and aquifer water and produced water (recovered from crude oil) or some combination is also used. The water injection pipelines (WIP) usually are carbon steel and often are many kilometres long. Because the insides of the pipes usually are not coated, the adverse operational environment means that internal corrosion is an on-going problem for many water injection pipelines. A corrosion problem of much concern in practice is the severe internal corrosion at the lower part of water injection pipelines in near-horizontal positions, in some cases, severe metal loss threatening the integrity of the pipelines. This type of corrosion is known variously as channelling corrosion, 6 o’clock corrosion, and bottom of the line corrosion. The examination of field observations suggests both under-deposit corrosion (UDC) and microbiologically influenced corrosion (MIC) are likely to be associated with the phenomenon. However, the mechanism of this phenomenon is still not fully understood. This thesis reports the observations of long-term corrosion of model steel pipes in a pilot laboratory study aimed at improving the understanding of development of channelling corrosion in offshore water injection pipelines. Half-pipe steel specimens were exposed continuously to stagnant and simulated deoxygenated seawater in the presence of mixed deposits for up to 365 days. The relative contributions of MIC, UDC and nitrate addition to corrosion development were investigated using four different test environments. The steel specimens were recovered after 12, 180 and 365 days of exposure and the changing surface topography was examined by Scanning Electron Microscopy (SEM) and optical microscope. The evolution of corrosion products were analysed by SEM and Energy-dispersive X-ray spectroscopy (EDS). The pit depths were measured by digital Linear Variable Differential Transformer (LVDT). These techniques present detailed graphical, morphological and chemical results of the corrosion process of mild steel in presence of deposits exposed to deoxygenated seawater. The observations show the synergistic effect of MIC and under-deposit corrosion led to severe localized corrosion. Nitrate addition caused most severe localized corrosion. This is linked to the enhanced MIC and the added nitrate plays the role of a source of critical nutrient. The progression of maximum pitting depth with increased exposure period was evaluated and a preliminary extreme value analysis of variability in maximum pit depth is presented. It is found that extreme value distribution examination shows Gumbel function is not appropriate to describe all the pit depth data. Frechet distribution is a better model to deal with the variability of the deepest pits. Finally, it is proposed that the continuous propagation of broad pits with the initiation of newer pits may explain the ultimate formation of channelling corrosion seen in practical water injection pipelines. Suggestions are provided for industrial practice on controlling rust deposition and MIC. The extreme value analysis of the pit depth data is also important for predicting failure probability due to pitting corrosion. In sum, the results in this thesis have implications for the corrosion management of water injection pipelines in the offshore oil industry.
Chang, Zhen-Tian Civil & Environmental Engineering Faculty of Engineering UNSW. "Corrosion rate of steel reinforcement in concrete in seawater and influence of concrete crack width." 2007. http://handle.unsw.edu.au/1959.4/40539.
Full textEscue, William David. "Characterization of the corrosion behavior of high damping alloys in seawater." Thesis, 1987. http://hdl.handle.net/10945/22663.
Full textLiang, Mengxia. "Characterisation of pitting corrosion for aluminium alloys in natural seawater and freshwater immersion environments." Thesis, 2019. http://hdl.handle.net/1959.13/1407935.
Full textAluminium alloys are increasingly being used in structural and commercial infrastructure, such as aerospace, transportation, architecture, defence and marine industries, due to their low density, desired strength, excellent corrosion resistance and other combined properties. For this reason, structural safety is paramount as it can be influenced by the long-term exposure of aluminium alloys to various environments. In wet environments or when in contact with water, aluminium alloys are prone to pitting corrosion, which can be very detrimental. Pitting leads to rapid attacks of discrete areas on the metal surface, while the adjacent surface can remain virtually unaffected. It is vicious and insidious and may result in perforation or contribute to stress-induced failure. For safety and economic reasons, it is important to be able to predict future corrosion and estimate the lifetime of aluminium components. This requires a thorough understanding of the progression of pitting and reliable corrosion data, measured in years, which is essential to building an accurate corrosion prediction model. Many decades of research and investigation have provided for a considerable understanding of the onset and early development of pitting. Unfortunately, relatively few investigations have been dedicated to longer-term (especially that expressed in years) pitting behaviour. In addition, recent research on AA6060-T5 aluminium alloys that are continuously immersed in natural seawater for 2(+), 3, 3.5 and 4 years showed that the long-term pitting corrosion of aluminium alloys is a very complex process. Several different types of pitting morphologies were observed on the metal surface. The development of mass loss at the maximum pit depths as a function of time showed a trend similar to the early part of a bi-modal model, as previously proposed based on long-term pitting corrosion data of steels. In order to have a better understanding of how these complex corrosion morphologies develop and whether this bi-modal model trend can also be applied to other series of aluminium alloys, a group of long-term test programs were performed. This thesis reports observations on the complex, long-term pitting corrosion of AA5005-H34 aluminium alloys in six different immersion environments, all in natural seawater or freshwater. Test coupons were recovered periodically after exposure periods of 1 month, 3 months, 6 months, 12 months, 18 months and 2 years. The corrosion properties including pitting morphologies, corrosion products, mass loss and maximum pit depths for each exposure period were carefully investigated. The changing pitting morphologies and their relationship with the development of mass loss and pit depth as a function of time were analysed and discussed. Extreme value theory was used to analyse the uncertainty of the pit depth data. Also, the likely factors influencing pitting corrosion were discussed. The results showed that pitting morphologies varied significantly in different immersion environments. Within the same immersion environment, the dominant pitting morphology also changed after different amounts of exposure. It was found that the mass loss, the average of the 15 deepest pit depths and the maximum pit depths tended to develop in stages as exposure time increased. Overall, the trends of the datasets for the mass loss and pit depths were similar to that of the early part of a bi-modal trend as a function of time. Corrosion products played an important role in the bi-modal development of pitting. Also, for the deeper pits, specifically those ‘dimple’-like pits that developed in a long-term steady phase, Frechet extreme value distribution showed a slightly better distribution than Gumbel distribution.
Wu, Bee Fong, and 吳碧峰. "Effect of Corrosion Inhibitors on Corrosion Rates of Mild Steel in 3.5% NaCl Solution and Artificial Seawater Cont- -taining Various Concentrations of NaClO." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/57083511168729976705.
Full text文化大學
應用化學系
83
NaClO is widely used to eliminate macroorganisms and microorganisms on metal surface in marine enviroment,and prevent the acceleration corrosion that is caused by fouling problems. NaClO is a strong oxidizing agent, may remain in aqueous solutions, and result another severe corrosion problem. In this study, two corrosion inhibitors were chosen to evaluate their inhibitor efficiencies for steel used in 3.5% NaCl solution and artificial seawater containing various concentration (0.1-30 mL/L) of NaClO. The corrosion rate of steel increases with increase concentration of NaClO. Sodium chromate is an effective passivating inhibitor for all test solutions. The corrosion potentials of steel move to more noble (positive) value with the addition of chromate, and corrosion rate can be retarded. Lime is a cathodic inhibitor ,also causes the corrosion potential move positive,and slows down corrosion rate. Lime is not suitable to apply in the aqueous solution containing high concentrate NaClO.
Chang, Po-Hung, and 張伯鴻. "The optimal control for corrosive effluent from the seawater desalination plant." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/30822934360445542257.
Full text國立成功大學
環境工程學系碩博士班
92
Shortly after the inauguration of Wu-Kan seawater desalination plant in Peng-Hu, leaching of materials from cement-mortar linings of the ductile-iron pipes and complaints about red-water from the customers were reported. These were thought to be caused by the aggressive effluent from the RO membrane, which removed most ions from seawater. The purpose of this research is to select the appropriate post-treatment processes to reduce the corrosiveness of the effluent from the desalination plant. First, the literature, concerned with the corrosion control for public water supply, especially for those involved with seawater desalination, was searched. Then the effluent from the Wu-Kan desalination plant was collected and the water quality analyzed. Based on the result from water quality analysis, the appropriate chemicals and dosage needed to restore its chemical stability were predicted theoretically. After chemical conditioning, the water quality was reanalyzed, and the values of various corrosion indexes were calculated. Following the method “Laboratory Immersion Corrosion Testings,” of ASTM G31, the corrosion intensity of the post-treated water was measured. The coupons used in these tests were made of ductile iron. Then correlation between the various corrosion indexes, namely LSI (Langelier Saturation Index), RSI (Ryznar Stability Index), and CCPP (Calcium Carbonate Precipitation Potential), and the lab-measured corrosion rate were evaluated. In addition, alkaline media filter with marble as media and coupling with CO2 addition was also evaluated as alternative post-treatment process. Based on the results from this study, the laboratory immersion corrosion testings are effective for evaluating various post-treatment processes for effluent from seawater desalination plant. However, attention should be paid to providing appropriate mixing and dissolved oxygen in the reacting vessel. Comparing the corrosion inhibition efficiency of the three post-treatment processes, namely lime and carbon dioxide, sodium bicarbonate or carbonate, and alkaline media filter, the results show that lime and carbon dioxide process was very efficient. At Ca(OH)2 dosage of about 60 mg/L and adding sufficient amount of CO2 to keep pH value at about 8.0, the treated water, with LSI value at about 0.2, was chemically stable concerning corrosion. Generally speaking, when the corrosion index of the post-treated water meets the following criteria: LSI 0.2, RSI 8, or CCPP 0, the corrosion rate is limited. Adding only sodium bicarbonate or sodium carbonate, even at very high dosages, was not very effective for corrosion control. These two alkaline agents must be coupled with lime and CO2 in order to adjust the value of corrosion index to the desired range. The water quality of the effluent from the alkaline media filter was similar to that from the lime-CO2 process, and therefore also demonstrated similar corrosion rate. However, the granular size of the alkaline media was found to have profound effect on the performance of the filter. Further, under similar value of corrosion index, the post-treated waters with higher calcium content were found to have lower corrosion rate than those with higher alkalinity value. This probably is related to the formation of protective calcium carbonate layer on metal surface.