Дисертації з теми "Corrosion patina"

Fundamental understanding of atmospheric corrosion mechanisms requires an in-depth understanding on the dynamic interaction between corrosive constituents and metal/alloy surfaces. This doctoral study comprises field and laboratory investigations that assess atmospheric corrosion and metal release processes for two different groups of alloys exposed in chloride-rich environments. These groups comprise two commercial Zn-Al alloy coatings on steel, Galfan™ (Zn5Al) and Galvalume™ (Zn55Al), and four copper-based alloys (Cu4Sn, Cu15Zn, Cu40Zn and Cu5Zn5Al). In-depth laboratory investigations were conducted to assess the role of chloride deposition and alloy microstructure on the initial corrosion mechanisms and subsequent corrosion product formation. Comparisons were made with long-term field exposures at unsheltered marine conditions in Brest, France. A multitude of surface sensitive and non-destructive analytical methods were adopted for detailed in-situ and ex-situ analysis to assess corrosion product evolution scenarios for the Zn-Al and the Cu-based alloys. Scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) were employed for morphological investigations and scanning Kelvin probe force microscopy (SKPFM) for nobility distribution measurements and to gain microstructural information. SEM/EDS, infrared reflection-absorption spectroscopy (IRAS), confocal Raman micro-spectroscopy (CRM) and grazing incidence x-ray diffraction (GIXRD) were utilized to gain information on corrosion product formation and possibly their lateral distribution upon field and laboratory exposures. The multi-analytical approach enabled the exploration of the interplay between the microstructure and corrosion initiation and corrosion product evolution. A clear influence of the microstructure on the initial corrosion product formation was preferentially observed in the zinc-rich phase for both the Zn-Al and the Cu-Zn alloys, processes being triggered by microgalvanic effects. Similar corrosion products were identified upon laboratory exposures with chlorides for both the Zn-Al and the Cu-based alloys as observed after short and long term marine exposures at field conditions. For the Zn-Al alloys the sequence includes the initial formation of ZnO, ZnAl2O4 and/or Al2O3 and subsequent formation of Zn6Al2(OH)16CO3·4H2O, and Zn2Al(OH)6Cl·2H2O and/or Zn5(OH)8Cl2·H2O. The patina of Cu sheet consists of two main layers with Cu2O predominating in the inner layer and Cu2(OH)3Cl in the outer layer, and with a discontinuous presence of CuCl in-between. Additional patina constituents of the Cu-based alloys include SnO2, Zn5(OH)6(CO3)2, Zn6Al2(OH)16CO3·4H2O and Al2O3. General scenarios for the evolution of corrosion products are proposed as well as a corrosion product flaking mechanism for some of the Cu-based alloys upon exposure in chloride-rich atmospheres. The tendency for corrosion product flaking was considerably more pronounced on Cu sheet and Cu4Sn compared with Cu15Zn and Cu5Al5Zn. This difference is explained by the initial formation of zinc- and zinc-aluminum hydroxycarbonates Zn5(OH)6(CO3)2 and Zn6Al2(OH)16CO3·4H2O on Cu15Zn and Cu5Al5Zn, corrosion products that delay the formation of CuCl, a precursor of Cu2(OH)3Cl. As a result, the observed volume expansion during transformation of CuCl to Cu2(OH)3Cl, and the concomitant flaking process of corrosion products, was less severe on Cu15Zn and Cu5Al5Zn compared with Cu and Cu4Sn in chloride-rich environments. The results confirm the barrier effect of poorly soluble zinc and zinc-aluminum hydroxycarbonates Zn5(OH)6(CO3)2 and Zn6Al2(OH)16CO3·4H2O, which results in a reduced interaction between chlorides and surfaces of Cu-based alloys, and thereby reduced formation rates of easily flaked off corrosion products. From this process also follows reduced metal release rates from the Zn-Al alloys.
Bättre molekylär förståelse för metallers atmosfäriska korrosion kräver en fördjupad kunskap i det dynamiska samspelet mellan atmosfärens korrosiva beståndsdelar och metallytan. Denna doktorsavhandling omfattar laboratorie- och fältundersökningar av korrosions- och metallfrigöringsprocesser av två grupper av legeringar som exponerats i kloridrika atmosfärsmiljöer: två kommersiella Zn-Al beläggningar på stål, Galfan™ (Zn med 5% Al, förkortat Zn5Al) och Galvalume™ (Zn55Al), samt fyra kopparbaserade legeringar (Cu4Sn, Cu15Zn, Cu40Zn och Cu5Zn5Al). Undersökningar har genomförts i renodlade laboratorie-miljöer med för-deponerade NaCl-partiklar i en atmosfär av varierande relativ fuktighet. Syftet har varit att utvärdera betydelsen av kloriders deposition och legeringarnas mikrostruktur på korrosionsmekanismen samt bildandet av korrosionsprodukter. Jämförelser av korrosionsmekanismer har även gjorts efter flerårsexponeringar av samma legeringar i en marin fältmiljö i Brest, Frankrike. Undersökningarna har baserats på ett brett spektrum av analysmetoder för detaljerade studier dels under pågående atmosfärisk korrosion (in-situ), och dels efter avslutad korrosion (ex-situ). Legeringarnas mikrostruktur och tillhörande variation i ädelhet hos olika faser har undersökts med svepelektronmikroskopi och energidispersiv röntgenmikroanalys (SEM/EDS) samt med en variant av atomkraftsmikroskopi (engelska: scanning Kelvin probe force microscopy, SKPFM). Korrosionsprodukternas tillväxt har analyserats in-situ med infraröd reflektions-absorptionsspektroskopi (IRAS), samt morfologi och sammansättning av bildade korrosionsprodukter ex-situ med SEM/EDS, konfokal Raman mikro-spektroskopi (CRM) samt röntgendiffraktion vid strykande ifall (GIXRD). Det multi-analytiska tillvägagångssättet har medfört att det komplexa samspelet mellan de skilda legeringarnas mikrostruktur, korrosionsinitiering och bildandet av korrosionsprodukter kunnat studeras i detalj. En tydlig påverkan av mikrostruktur på det initiala korrosionsförloppet har kunnat påvisas. Korrosionsinitieringen sker företrädesvis i mer zinkrika faser för såväl Zn-Al- som Cu-Zn-legeringar och orsakas av mikro-galvaniska effekter mellan de mer zinkrika, mindre ädla, faserna och omgivande faser. Deponerade NaCl-partiklar påskyndar den lokala korrosionen oberoende av mikrostruktur. Snarlika sekvenser av korrosionsprodukter har kunnat påvisas såväl efter laboratorie- som fältexponeringar. För Zn-Al-legeringar bildas först ZnO, ZnAl2O4 och/eller Al2O3, därefter Zn6Al2(OH)16CO3·4H2O och Zn2Al(OH)6Cl·2H2O och/eller Zn5(OH)8Cl2·H2O. På ren koppar bildas ett inre skikt dominerat av Cu2O, ett mellanskikt av CuCl och ett yttre skikt med i huvudsak Cu2(OH)3Cl. Beroende på legeringstillsats har även SnO2 och Zn5(OH)6(CO3)2 kunnat identifieras. En mekanism för flagning av korrosionsprodukter på kopparbaserade legeringar i kloridrika atmosfärer har utvecklats. Tendensen för flagning har visat sig vara mycket mer uttalad på ren Cu och Cu4Sn än på Cu15Zn och Cu5Al5Zn. Skillnaden kan förklaras med hjälp av det tidiga bildandet av Zn5(OH)6(CO3)2 och Zn6Al2(OH)16CO3·4H2O på Cu15Zn och Cu5Al5Zn som fördröjer bildandet av CuCl, en föregångare till Cu2(OH)3Cl. Därigenom hämmas även den observerade volymexpansionen som sker när CuCl omvandlas till Cu2(OH)3Cl, en process som visar sig vara den egentliga orsaken till att korrosionsprodukterna flagar. Resultaten bekräftar barriäreffekten hos de mer svårlösliga faserna Zn5(OH)6(CO3)2 och Zn6Al2(OH)16CO3·4H2O, vilken dels resulterar i en minskad växelverkan mellan klorider och de legeringsytor där dessa faser kan bildas, och dels i en reducerad metallfrigöringshastighet.

QC 20140915

Autocorr, RFSR-CT-2009-00015 Corrosion of heterogeneous metal-metal assemblies in the automotive industry
Atmospheric corrosion and environmental metal dispersion from outdoor construction materials

No acervo que compõem o patrimônio cultural, há muitos utensílios, obras de arte, monumentos, etc., que são feitos de metais. Mas dentre os diversos metais existentes, o cobre possui uma posição de destaque na história, pois este foi o primeiro utilizado pela humanidade. Os metais quando expostos à atmosfera podem sofrer processos de corrosão, o que pode comprometer um artefato histórico. No cobre e suas ligas, o produto dos processos de corrosão é denominado pátina. O estudo das pátinas e das ligas que compõe a matriz, no qual a pátina se forma, é de fundamental importância para a compreensão dos processos de corrosão. Com esta informação, puderam-se determinar as melhores técnicas de conservação e restauração que devem ser aplicadas. No presente estudo utilizou-se pátinas artificiais, que já são amplamente conhecidas, e possibilitam a simulação de pátinas naturais, além de ser possível utilizá-las na recolocação de pátinas que fora removidas e/ou perdidas de peças metálicas. Em um estudo anterior foram produzidas pátinas artificiais a partir de três soluções utilizando dois procedimentos de preparação e a análise foi realizada através das técnicas: EIS (Espectroscopia por Impedância Eletroquímica), MEV (Microscopia Eletrônica de Varredura), e XRD (Difração de Raio X), que são consideradas técnicas micro-destrutivas. No presente estudo, destas mesmas pátinas, utilizou-se para análise as técnicas de PIXE (Emissão de Raio X Induzido por Partícula) e ED-XRF (Fluorescência de Raio X por Dispersão de Energia), ambas não destrutivas e, no caso de ED-XRF, mais frequentemente, possível ser utilizada in situ. Estas técnicas permitem a analise de obras de arte em atmosfera, em um arranjo externo, o que contribui para a análise de peças de diferentes formas e tamanhos. Os resultados obtidos mostraram que o PIXE possui uma melhor caracterização de elementos leve, enquanto que o ED-XRF é melhor para elemento pesados. Na comparação entre PIXE interno e externo, observou-se que a montagem externa é suficiente na análise desse tipo de material. As medidas de padrões de aço validaram a técnica PIXE para análise de alvos grossos e permitiram quantificar os elementos presentes nas amostras. Tanto PIXE, quanto ED-XRF, mostraram nas análises das amostras os elementos que estão presentes nas soluções aplicadas. Além disso, houve um aumento do enxofre em algumas amostras e pátinas, e isto pode indicar que este elemento foi agregado com o tempo nas amostras, devido à exposição à atmosfera. Em comparação ao estudo anterior, que caracterizou a composição das camadas de pátinas em amostras semelhantes, foi possível mostrar que se pode determinar e quantificar com PIXE eED-XRF os elementos presentes sem que seja necessária a retirada do material a ser analisado, principalmente se aplicadas para a análise de peças com valor histórico e cultural. O estudo utilizando as técnicas PIXE e/ou ED-XRF, juntamente com técnicas EIS, SEM e XRD, torna as respostas mais completas, mas nem sempre isso é possível em se tratando de bens do patrimônio histórico, cultural e artístico.
The collection that composes the cultural patrimony has many utensils (vessels, pottery, adornment), works of art, monuments, etc., that are made of metals. However amongst the diverse existing metals, copper possesses a position of historical prominence, since this metal was the first one to be used by humanity. Metals when displayed in the atmosphere, can suffer processes corrosion which can destroy partially or completely the historical object. In copper and its alloys, the product of the corrosion processes is called patina. Analyses of the patina and the matrix alloy material are necessary to understand the corrosion processes and its development. The analyses are also needed to study the alterations imposed on an artifact in order to develop an adequate conservation and restoration treatment techniques. In the present work well known artificial patinas were used and can simulate the natural ones besides permitting to use them in the replacement of lost patinas that have been removed and/or lost in metalic parts. A previous study was realized with artificial patinas produced from three solutions and two different procedures of application. These patinas were analyzed by different techniques such as: EIS (Electrochemical Impedance Spectroscopy), SEM (Scanning Electron Microscopy), and XRD (X-ray Diffraction), which are micro-destructive methods. In the present study, the same samples were analyzed by PIXE (Particle Induced X-ray Emission) and ED-XRF (Energy Dispersive X-ray Fluorescence) techniques, both not destructive, and in the case of ED-XRF, more frequently, it can be used in situ. These methods allow the analyses of works of art of different forms and sizes in the atmosphere, in an external arrangement. The results have shown that PIXE has a better characterization of light elements, whereas the ED-XRF is better for heavy elements. The comparison of internal and external PIXE measurements showed that the PIXE external setup is enough for the analysis of this type of material. The PIXE results of steel standards had validated the technique PIXE for analysis of thick targets and had allowed the quantification of the elements presents in the samples. PIXE and ED-XRF analyses had shown the principal elements present in the samples and in the solutions. Moreover, it was possible detect an increase of sulphur in some samples and patinas, indicating that this element is being absorbed by the samples due to the exposition to the atmosphere. This work also shows that it is possible to determine and quantify with PIXE and ED-XRF the elements present in the samples, without any extraction of material and it is important mainly if applied to the analysis of historical and cultural objects. A study using suitable combination of techniques, as used in the previous study (EIS, SEM e XRD) coupled to PIXE and/or ED-XRF techniques can give a complete characterization of the corrosion compounds, but sometimes the complete combination of techniques is impossible if dealing with artistic and cultural historic objects.

This work deals with the influence of atmospheric corrosion on high-cycle fatigue properties of a weathering steel ATMOFIX B. New experimental data on fatigue strength of a steel exposed for 20 years to an atmospheric corrosion were compared to those characterizing the base material. Reduction of the fatigue lifetime of the exposed material compared with the base material was predicted on the basic of fractographic examination of fracture surfaces and the influence of surface notches on fatigue strength. The predicted results agree well with the experimental results.

Le but de notre étude est de réaliser un modèle numérique traitant le problème de contact patin-pivot dans un palier à patins oscillants et de déterminer les coefficients dynamiques (raideur et amortissement). Ce problème particulier rentre dans le cas général du contact sec et lubrifié. L'identification du contact patin pivot confirme que le contact élastique est le modèle le mieux adapté à ce problème. Les modèles du contact statique et statique évolutif sont retenus. Des outils numériques nouveaux ont été mis en œuvre pour résoudre le contact élastique sous l'hypothèse de massif semi-infini. La loi de Coulomb permet de caractériser globalement les interactions entre le contact normal et le contact tangentiel. Le programme du contact statique permet de déterminer les inconnues (zones de contact, champs de pression, les raideurs du contact, etc. . . ). Le programme du contact statique évolutif permet d'étudier le phénomène d'hystérésis. La dissipation d'énergie due au frottement de Coulomb et le coefficient d'amortissement équivalent sont examinés.

Deterioration phenomena occurring on outdoor cultural heritage have been the subject of several studies, but relatively few works investigated the specific role of Particulate Matter (PM) in the corrosion of metals. This topic is really complex and, besides field exposures, accelerated ageing tests are also necessary to isolate and understand deterioration mechanisms due to PM. For this reason, the development of a methodology that allows to reproduce and analyze the effect of PM on alloys through accelerated ageing in climatic chamber has been started. On quaternary bronze specimens, single salts and a mix of them were deposited via two deposition methods: dry (directly depositing the salt on the surface) and wet (dropping a salt solution and drying it), simulating the initial chemical activation of the salts by RH% variations or by raindrops, respectively. Then, to better mimic the composition of real PM, a mixture containing a soluble salts, a mineral, a black carbon and an organic fraction was formulated and spread on the samples. The samples were placed in a climatic chamber and exposed to cyclic variations of T and RH for three weeks. The ageing cycles were set according to predictions on salt deliquescence/recrystallization through E-AIM model and to the evaluation of regional climatic data. The surface evolution was followed by SEM-EDX, Raman, AT-IR and UV-Vis Spectrophotometry. At the end of the test, mass losses were determined and corroded metals removed by pickling were analyzed by AAS. On the basis of the obtained results, the tested procedures seem to be promising in accelerating and mimicking realistic corrosion phenomena, as under the selected conditions, corrosion products typically found at different exposure time (from days to years) on outdoor bronzes were able to progressively form and evolve. Moreover, the two deposition modes simulating different condition of chemical activation of PM deposits allow to obtain complementary information.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Os dutos para transporte de petróleo e gás são um dos meios mais seguros e que menos agridem ao meio-ambiente, além de possuírem uma alta eficiência e produtividade. Mesmo tendo uma capacidade excepcional, eles são uma grande fonte de preocupação das companhias petrolíferas e estão sujeitos a diversos tipos de defeitos, dentre os quais o que mais se destaca são os defeitos causados por corrosão. Então, para que uma malha dutoviária opere com segurança, faz se necessário monitorar continuamente ela, para que defeitos encontrados sejam analisados de maneira rápida e confiável, verificando-se assim a integridade estrutural da região afetada. Neste contexto, a análise computacional pelo Método de Elementos Finitos (MEF) tem-se mostrado uma poderosa e eficiente ferramenta na avaliação estrutural de dutos com defeitos causados por corrosão, pois os resultados obtidos pelo método são mais rápidos e econômicos do que os conseguidos pelo método experimental, e bem mais precisos do que os obtidos pelos métodos analíticos. Ampliar com segurança a vida útil dos dutos transformou- se para os engenheiros uma tarefa fundamental e muito importante. Este trabalho teve como proposta, o desenvolvimento de um programa que automatizasse a geração de modelos computacionais identificados de defeitos utilizando malhas estruturadas e não estruturadas (malhas mistas) no mesmo modelo, através da implementação de funções escritas em linguagem de programação PCL (Patran Commando Language) e adicionadas ao programa PIPEFLAW (Cabral, 2007) desenvolvido pelo grupo PADMEC. Também foram construídos modelos computacionais de dutos com defeitos de corrosão com geometria irregular. Para a criação dos modelos foi empregado o programa comercial de pré e pósprocessamento MSC.PATRAN. Depois de concluídos, todos os modelos foram avaliados estruturalmente através da realização de análises não-lineares. Para esta etapa utilizou-se o programa comercial de simulação numérica o solver ANSYS. Por fim, são apresentados alguns exemplos de modelos de dutos gerados automaticamente, que utilizam malha mista, pelo programa PIPEFLAW. Os resultados dessas análises numéricas realizadas são comparados com resultados empíricos, numéricos e experimentais quando disponíveis na literatura. Também são apresentados alguns exemplos de modelos de dutos com defeitos de corrosão com geometria irregular construídos, e os resultados das análises numéricas realizadas nestes modelos para o estudo de suas capacidades estruturais

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A segurança operacional da malha de dutos de transporte de hidrocarbonetos é uma grande preocupação de todas as companhias de petróleo, devido aos imensos danos econômi-cos, sociais e em termos da imagem da companhia que um acidente de grande porte com um duto pode causar. Esta malha deve ser monitorada continuamente e problemas encontrados devem ser avaliados de forma confiável, a fim de analisar o comprometimento da integridade estrutural do duto e permitir que reparos necessários sejam realizados com segurança, antes que estes defeitos causem um acidente. No caso de defeitos causados por corrosão, a análise computacional com o Método dos Elementos Finitos (MEF) tem se mostrado uma das ferra-mentas mais eficientes para a avaliação correta da integridade estrutural de dutos com defei-tos. Estas ferramentas permitem considerar diretamente os fenômenos físicos envolvidos no processo de falha do duto resultando assim em resultados mais precisos que os encontrados por meio de modelos semi-empíricos e bem mais rápidos e econômicos que os obtidos através de experimentos em laboratório. A análise via o MEF, no entanto, requer uma grande especialização e um treinamento específico que não são característicos de todos os engenheiros de tubulações. O processo para a criação de bons modelos computacionais para um defeito, que inclui a modelagem fiel da geometria deste defeito e a geração de uma malha apropriada, demanda uma interação manual constante do engenheiro, é demorado e muito repetitivo, e por estas razões muito propenso a erros. Normalmente, este procedimento é repetido desde o início para cada novo problema analisado, em um patente desperdício de recursos humanos qualificados. A principal proposta deste trabalho foi desenvolver um conjunto de ferramentas com-putacionais que produzem automaticamente modelos de dutos com defeitos, prontos para se-rem analisados em programas comerciais que implementam o MEF, a partir de alguns parâ-metros que localizem e forneçam as dimensões principais do defeito ou de uma série de de-feitos. Estas ferramentas são baseadas no programa comercial de pré e pós-processamento MSC.PATRAN e foram produzidas por meio da linguagem de programação PCL (Patran Command Language). O programa de geração automática de modelos (denominado programa PIPEFLAW) tem interface gráfica simplificada e personalizada, de forma que um engenheiro, com noções básicas de simulação computacional com elementos finitos, possa gerar rapida-mente modelos que resultem em simulações precisas e confiáveis. A realização das análises não-lineares foi feita por meio de um script implementado na linguagem de programação PYTHON a partir do qual toda a análise é gerenciada através da execução automática de tarefas pré-determinadas. Assim, a cada iteração da análise, o sol-ver ANSYS é acionado pelo script e em seguida, os resultados gerados durante aquela iteração são lidos e interpretados pelo script possibilitando que os critérios de convergência e incremento de carga, pré-definidos pelo usuário, sejam aplicados automaticamente, diferen-temente do procedimento usual quando se ativa os critérios de convergência e de incremento de carga determinados pelo solver . Por fim, são apresentados alguns exemplos de modelos de dutos gerados automatica-mente pelo programa PIPEFLAW. Os resultados de análises numéricas, realizadas utilizando as ferramentas desenvolvidas neste trabalho, são comparados com resultados empíricos, nu-méricos e experimentais disponíveis na literatura com o objetivo de validar as ferramentas aqui apresentadas

Le but de ce travail est l'étude de la corrosion du cuivre pur et du cuivre recouvert d'une couche de patine artificielle développée dans une solution de sulfate. Ces études ont été menées dans des solutions contenant des espèces agressives caractéristiques de l'atmosphère de la ville de São Paulo (Brésil), à savoir les ions chlorure, sulfate et ammonium, ajoutés respectivement sous forme de NaCl, Na2SO4 et (NH4)2SO4, afin d'examiner la stabilité de la couche de patine dans ces milieux. Le comportement électrochimique a été caractérisé au moyen de voltammétrie cyclique et par spectroscopie d'impédance électrochimique, tandis que la spectroscopie Raman, la diffraction des rayons X et la microscopie électronique à balayage couplé à l'analyse élémentaire EDAX ont été employés pour analyser la composition chimique, structurale et microstructurale des échantillons. La caractérisation électrochimique a été réalisée soit en utilisant des électrodes classiques avec une grande surface de travail, soit en utilisant des techniques de microélectrochimie comme la microélectrode à cavité et la microcellule électrochimique. Les caractérisations microstructurales et chimiques ont révélé une structure bicouche pour la patine artificielle avec une couche externe poreuse composée principalement de brochantite et une couche interne plus compacte composée d'oxyde de cuivre. Cette structure est conforme à celle des patines de sulfate obtenues dans conditions réelles d'expositions extérieures. Les résultats des tests électrochimiques avec les électrodes classiques ont montré que le comportement d'électrode dépendait extrêmement de la composition d'électrolyte et que la solution contenant des ions d'ammonium est la plus agressive tant pour le cuivre nu que pour le cuivre recouvert d'une couche de patine. Les expériences réalisées avec la microcellule ont permis de montrer l'existence de domaines avec des activités électrochimiques très différentes sur la surface patinée, tandis que l'utilisation de la microélectrode de cavité a montré que la patine de cuivre est électrochimiquement active dans les trois électrolytes.

Le phénomène de stiction se traduit à l’interface disque-patin de frein par l’adhésion du patin au disque lors d’un serrage suffisamment long du frein de parking. Les mécanismes à l’origine de ce phénomène sont, à ce jour, largement inexpliqués. Cependant, à partir d’observations effectuées sur des surfaces de couples disque-patin ayant subi une stiction, l’hypothèse selon laquelle les produits de corrosion du disque, en s’incrustant dans les pores du matériau de friction, seraient à l’origine de ce phénomène, a été privilégiée. Les travaux de cette thèse ont porté sur la compréhension du phénomène de stiction en s’articulant sur trois volets qui sont : (a) la caractérisation du comportement électrochimique de divers couples disque-patin à l’aide de mesures de suivi du potentiel de corrosion, de spectroscopie d’impédance électrochimique et de voltampérométrie, (b) l’étude mécanistique des phénomènes de corrosion à l’interface disque-patin et (c) l’étude de l’effet de la pression sur les phénomènes de corrosion du couple disque-patin. L’étude sans force de serrage nous a permis, d’une part, de mettre en évidence une réactivité exacerbée du disque en présence du patin et d’autre part d’établir un critère de sélection de couple disque-patin. Le suivi du déplacement du patin lors des mesures électrochimique sous presse a permis de mettre en évidence que les produits de corrosion, en s’accumulant à l’interface disque-patin, exerçaient une force sur le patin, confirmant l’hypothèse émise au cours de cette thèse pour expliquer le phénomène de stiction
The phenomenon of stiction occurs at the pad-brake disc interface by the adhesion of the pad to the disc when the parking brake is applied long enough. The mechanisms behind this phenomenon are, to date, largely unexplained. However, from observations made on surfaces of disc-pad pairs having undergone a stiction, the hypothesis according to which the corrosion products of the disc, by becoming encrusted in the pores of the friction material, would be at the origin of this phenomenon, was privileged. The work of this thesis focused on understanding the phenomenon of stiction by focusing on three components which are: (a) the characterization of the electrochemical behavior of various disc-pad couples using measurements to monitor the corrosion potential, electrochemical impedance spectroscopy and voltammetry, (b) the mechanistic study of corrosion phenomena at the disc-pad interface and (c) the study of the pressure effect on corrosion phenomena of the disc-pad couple. The study without a clamping force allowed us, to demonstrate an exacerbated reactivity of the disc in the presence of the pad and to establish a selection criterion for the disc-pad torque. Monitoring the movement of the pad during electrochemical measurements with a clamping force revealed that corrosion products, accumulating at the disc-pad interface, exerted a force on the pad, confirming the hypothesis put forward during this thesis to explain the phenomenon of stiction

The presence of dirt, soil, aged polymers or corrosion patinas can hinder the readability of artworks; in these cases, non-invasive and controlled removal is essential. Nanostructured fluids (NSFs) - such as micellar solutions and microemulsions- allowed achieving this purpose, decreasing, at the same time, the drawbacks related to the use of solvents. In the last decades, several cleaning fluids have been developed; surfactants, in particular, have a crucial role in the NSFs’ formulations. For this reason, the research of innovative and highly performing amphiphiles represents one of the main goals in modern conservation science, in order to develop safer and greener systems. Two different NSFs were prepared with MPD surfactant and their interaction with soil and polymeric layers was evaluated through several techniques (CLSM, photographic observation, contact angle and surface tension measurements). Moreover, a comparison with a conventional nonionic surfactant (PDE) was made. MPD-based NSFs were found to be more effective in cleaning surfaces, also without mechanical action. Confining cleaning fluids in retentive matrices like gels represents one of the most powerful strategies to obtain greater control of the cleaning action. Two different pHEMA-based semi-IPNs were used as scaffold for a high selective agent (i.e., TEPA) able to remove corrosion products without affecting the protective cuprite layers. Changes in gels’ structure were evaluated by means DSC, TGA and SEM analysis before and after the interaction with the copper alloys; Cu(II) ion adsorption kinetics were used to assess the effect of the gels’ structure on the adsorption process. The pHEMA-based gels, classified as “rigid systems”, are not suitable for the treatment of bronze sculpture characterized by deep cavities and high reliefs. To overcome these limitations, TEPA was confined into a PVA-based film (HVPD) forming system. Thanks to its viscoelastic properties and its ability to combine a chemical action with a mechanical one, the HVPD represents a good option in these cases. The physico-chemical characterization was carried out to evaluate the effect of TEPA-addition on (1) the kinetics of the film formation, quantified through gravimetric and rheological measurements, and on (2) the final films’ properties, determined by DSC, ATR-FTIR and SEM analysis. 2D FTIR FPA Imaging confirmed the complete removal of corrosion products, the preservation of cuprite layers and the absence of residues on the mock-up surfaces after the treatment with both semi-IPNs and HVPDs. Finally, tests on real cases study are presented.

碩士
國立臺北科技大學
有機高分子研究所
101
The national defence , economic development, and people''s livelihood of a country are closely bound up with petrochemical industry ,its development condition depends on the cost of acquisition of crude oil, improvement of refine process, complete Supply Chains , and wholesome sales market. In order to reach extensive growth environment, and expand production capacity constantly, there must be increase more tank pressure vessels and pipeline relatively. But all most petrochemical industry factory’s environment are originally comparatively abominable .According to the the investigation of API, due to equipment failure or leakage of pipelines and other major accidents caused by the ratio of well over 40%, among them, the highest proportion of corrosion and fatigue by 41%, and consume considerable costs and terrible industrial safety. Against corrosion related research, is nothing more than the development of materials for metal corrosion (such as all kinds of stainless steel), and corrosive environment factors and corrosion protection materials research (Such as anti-corrosion coatings and corrosion inhibitors).Corrosion inhibitors due to a good effect and high economic value, it can be said now is the application of anti-corrosion technology in one of the methods most widely. Corrosion inhibitors are used in cooling water systems, oil and gas fields and paint coatings. Its technology and patents related development is already very mature. According to the World Intellectual Property Organization survey, proper use patent information can shorten development time 60%, saving 40% of R & D funding. This study focused on the use of patent analysis of corrosion inhibitor in the petrochemical industry in the cooling water system . To retrieve a collection of patents completed after studying patent summary table. And then ,compile a patent map and patent management chart to analyze the corrosion inhibitor materials R & D technology Finally, we want to use above-mentioned patentinformation, make related petrochemical plants develop future strategies to improve equipment corrosion helpful and understanding future trends in technology of corrosion inhibitors.

Объектом исследования является идея осуществления производства антикоррозийных продуктов. Целью работы является обоснование экономической целесообразности реализации проекта по производству антикоррозийных продуктов. В процессе выполнения работы были получены следующие результаты. В рамках изучения методических подходов к оценке экономических перспектив были даны определения экономического и маркетингового анализа, определены их основные методы и задачи. А также составлена авторская классификация антикоррозионных продуктов, учитывающая их ключевые признаки. Результаты анализа рыночных и перспектив позволили выявить основных потребителей и конкурентов интересующего отраслевого рынка, а также позволили определить оптимальный объем выпуска антикоррозийного продукта и его среднерыночную стоимость. Таким образом, оптимальный объем выпуска, не нарушающий сложившегося рыночного равновесия, составляет порядка 30 тонн, а среднерыночная стоимость 1 тонны продукта составляет 100-110 тыс. рублей. Результаты патентного исследования, проведенного в рамках оценки научно-технических перспектив, позволили определить динамику патентования и выявить аналогичные технические решения. На основе результатов проведенного патентного исследования пределен средний срок жизни проекта по производству железооксидного пигмента с противокоррозионными свойствами – 4 года. Научно-практическим результатом, полученным автором в процессе выполнения работы, является создание модели производства, учитывающей более эффективные инструменты реализации идеи по производству антикоррозийных продуктов. В рамках этой модели, с учетом выводов, сделанных в аналитической части работы, рассчитаны показатели экономической эффективности трех вариантов трансфера технологии.
The object of the study is the idea of the production of anti-corrosion products. The purpose of the work is to justify the economic feasibility of the project for the production of anti-corrosion products. The following results were obtained in the course of the work. As part of the study of methodological approaches to the assessment of economic prospects, the definitions of economic and marketing analysis were given, their main methods and tasks were determined. And also the author's classification of anticorrosion products, taking into account their key features. The results of market and prospects analysis allowed to identify the main consumers and competitors of the industry market of interest, as well as to determine the optimal volume of production of anti-corrosion product and its average market value. Thus, the optimal volume of output that does not violate the existing market balance is about 30 tons, and the average market value of 1 ton of product is 100-110 thousand rubles. The results of the patent research conducted in the framework of the assessment of scientific and technical prospects allowed to determine the dynamics of patenting and to identify similar technical solutions. Based on the results of the patent research, the average life of the project for the production of iron oxide pigment with anti – corrosive properties is limited to 4 years. The scientific and practical result obtained by the author in the process of the work is the creation of a production model that takes into account more effective tools for the implementation of the idea for the production of anti-corrosion products. Within the framework of this model, taking into account the conclusions made in the analytical part of the work, the indicators of economic efficiency of the three options for technology transfer are calculated.