Littérature scientifique sur le sujet « Corrosion patina »
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Articles de revues sur le sujet "Corrosion patina"
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Crespo, Ana, Iván Díaz, Delphine Neff, Irene Llorente, Sagrario Martínez-Ramírez et Emilio Cano. « Effect of Sulfuric Acid Patination Treatment on Atmospheric Corrosion of Weathering Steel ». Metals 10, no 5 (30 avril 2020) : 591. http://dx.doi.org/10.3390/met10050591.
Texte intégralRésumé :
The requirements for the formation of a protective patina on conventional weathering steels (WS) are well known in the scientific literature related to civil structures. However, these criteria are not always given due consideration when WS is used in cultural heritage, as in the case of sculptural work. An artificial patina was produced simulating artists’ working procedures using a direct patination technique, applying a solution of 10% H2SO4 on WS specimens. These were exposed for two years in the urban atmosphere of Madrid along with weathering steel specimens without artificial patina, called natural patina. The patinas generated have been analyzed using colorimetry, micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and thickness measurements.The artificial patina color formed hardly differs from the color that the natural patina acquires from practically the beginning of its formation in the atmosphere of Madrid. After two years, the atmospheric corrosion rate of patinated WS is lower than 6 µm/year. The sulfuric acid treatment accelerates the protective ability of the patina with respect to the natural patina according to the ratio goethite to lepidocrocite (α/γ). Chromium-rich goethite is located in the inner part of the artificial patina as well as chromium-rich ferrihydrite. Ferrihydrite may act as a precursor of nanophasic goethite.
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Li, Bingjie, Xudong Jiang, Yin Tu, Qiang Fu et Chunxu Pan. « “Inward Growth” Corrosion and Its Growth Mechanism in Ancient Chinese Bronzes ». MRS Advances 5, no 27-28 (2020) : 1457–66. http://dx.doi.org/10.1557/adv.2020.58.
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ABSTRACTWe divide the corrosion products on ancient bronzes into two categories, i.e., "inward growth" and “outward growth” corrosions. Several selected Chinese ancient bronzes with the "inward growth” corrosion are studied; and their chemical compositions, microstructures and morphologies are characterized systematically. According to the results, it is found that the “inward growth” corrosion can be further divided into three types, i.e., "noble patina", "noble-like patina" and "lamellar peeling patina". We propose that the growth mechanism of the “inward growth” corrosion is that the corrosion initiates at and develops along α-Cu phase. Furthermore, the effect of alloy Sn content on the “inward growth” corrosion is also studied.
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Myronyuk, I. F., I. M. Koval, V. I. Mandzyuk et I. P. Yaremiy. « Impurity Elements in a Lead Seals and Stamps of Middle Ages and Phase Composition of Their Patina ». Фізика і хімія твердого тіла 17, no 3 (15 septembre 2016) : 430–34. http://dx.doi.org/10.15330/pcss.17.3.430-434.
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The paper studied the elemental composition of lead alloys of appendage stamps and seals of Middle Ages, and the influence of impurity elements in the alloy and conditions for long-term storage of monuments on the course of corrosion processes and the formation of patina phase composition. Due to the influence of salts of orthophosphoric, hydrochloric and carbonate acids dissolved in the water environment on the artifacts surface patina coating is produced formed mainly of pyromorphite or pyromorphite and lead carbonate mixture. It was found that the corrosion rate of monuments depends essentially on the total content of Zn, Cd, Sn and Fe in lead alloy, which provide the protect for the main metal due to the electrochemical oxidation. Pink and brown colour of patina of certain attractions is associated with the pink colour of pyromorphite, which it takes as a result of isomorphic substitution of a small number of Pb atoms on Fe (III) ones. A colour of patine coating also depends on the content FeO, FeOOH and PbCO3∙Pb(OH)2.
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Crespo, Ana, Gloria Pérez, José A. Jiménez, Irene Llorente, Sagrario Martínez-Ramírez, Emilio Cano et Iván Díaz. « Evolution and Evaluation of Aesthetic Properties in Weathering Steel Accelerated Patinas : The Role of Lepidocrocite ». Metals 12, no 6 (7 juin 2022) : 977. http://dx.doi.org/10.3390/met12060977.
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Weathering steels are widely used in civil engineering, architecture and contemporary art due to their mechanical properties, their enhanced resistance to atmospheric corrosion as well as their aesthetic properties. Artists and blacksmiths often apply chemical treatments to obtain the appealing colors of a patina in a shorter period of time. However, the development of an accelerated patina may have an effect on the final appearance and color of the surface. With the aim of evaluating differences in color and studying the evolution of the surface, eight accelerated patinas were made and exposed to the atmosphere for periods of time of up to 24 months and were compared to a natural patina. The characterization studies showed the presence of lepidocrocite on the surface. A close inspection of the X-ray diffraction patterns showed the displacement of the (020) lepidocrocite reflection and asymmetric broadening of selective lines of this phase that were associated to stacking and twins faults, respectively. These faults decrease with the exposure time and are related to a maximum at 630 nm in the reflectance spectrum and the stabilization of the b* coordinate (yellow color). The colors of the accelerated patinas differ from the natural patina at short exposure times. However, they tend to converge at longer exposure times.
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Papadopoulou, Olga, et Panayota Vassiliou. « The Influence of Archaeometallurgical Copper Alloy Castings Microstructure towards Corrosion Evolution in Various Corrosive Media ». Corrosion and Materials Degradation 2, no 2 (19 mai 2021) : 227–47. http://dx.doi.org/10.3390/cmd2020013.
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The local patterns at the interfaces of corrosion stratification, developed on two archaeometallurgical bronzes (a Cu-Sn-Pb and a Cu-Zn-Sn-Pb alloy), in the as-cast condition, were assessed by OM and SEM-EDS systematic elemental chemical analyses. Previously, the alloys—whose metallurgical features and electrochemical behaviour were already well studied—have been subjected to laboratory corrosion experiments. The corrosion procedures involved electrochemical anodic polarization experiments in various chloride media: 0.1 mol/L NaCl, 0.6 mol/L NaCl and two other synthetic chloride-containing solutions, representing electrolytes present in marine urban atmosphere and in the soil of coastal sites. The characterization of the Cu-Sn-Pb alloy electrochemical patinas after anodic sweep (OCP+ 0.6 V) revealed that the metal in all electrolytes undergoes extensive chloride attack and selective dissolution of copper which initiates from the dendritic areas acting as anodic sites. The most abundant corrosion products identified by FTIR in all electrochemical patinas were Cu2(OH)3Cl), Cu2(OH)2CO3 and amorphous Cu and Sn oxides. The characterization of the Cu-Sn-Pb alloy electrochemical patina after slow anodic sweep (OCP+ 1.5 V) in 0.1 mol/L NaCl reveals selective oxidation of dendrites and higher decuprification rate in these areas. Corrosion products of Sn-rich interdendritic areas are dominated by oxygen species (oxides, hydroxides, hydroxyoxides) and Cu-rich dendrites by chlorides. In the case of Cu-Zn-Sn-Pb, Zn in dendritic areas is preferentially attacked. The alloy undergoes simultaneous dezincification and decuprification, with the former progressing faster, especially in dendritic areas. The two processes at the alloy/patina interface leave behind a metal surface where α-dendrites are enriched in Sn compared to the alloy matrix. The results of this study highlight the dynamic profile of corrosion layer build-up in bronze and brass. Moreover, the perception of the dealloying mechanisms progression on casting features, at mid-term corrosion stages, is extended.
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Królikowska, Agnieszka, Leszek Komorowski, Izabela Kunce, Damian Wojda, Katarzyna Zacharuk, Urszula Paszek, Tomasz Wierzbicki et Katarzyna Bilewska. « Corrosion Assessment of a Weathering Steel Bridge Structure after 30 Years of Service ». Materials 14, no 14 (6 juillet 2021) : 3788. http://dx.doi.org/10.3390/ma14143788.
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The first steel with improved resistance towards atmospheric corrosion, the so-called weathering steel, was patented in the USA in 1933 and was initially used for coal railway cars, and after that, in building and bridge engineering. Weathering steels show higher corrosion resistance than carbon steels in many types of atmosphere due to their ability to form a compact, stable, adherent and protective patina during the time of exposure. Morphological evaluation of the appearance of the corrosion product layer, together with phase analysis of its components, can enable determination of the type of patina and the degree of protection of the steel. To support the visual assessment of a patina, a check based on the qualitative and quantitative phase analysis of its components may be carried out, and the PAI (Protective Ability Index) can be calculated. The estimation of the corrosion processes on original Polish-made weathering steel (12HNNbA) was carried out on a 30-year-old bridge in Poland. There are some structural problems within the deck derived not only from corrosion but also steel cracking, both inside and outside the boxes, at different heights. Fourteen representative samples of patina were analysed and their phase structures were determined by the X-ray powder diffraction method. The PAIs were determined and analysed.
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Odnevall Wallinder, I., et C. Leygraf. « A Critical Review on Corrosion and Runoff from Zinc and Zinc-Based Alloys in Atmospheric Environments ». Corrosion 73, no 9 (4 mai 2017) : 1060–77. http://dx.doi.org/10.5006/2458.
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This critical review aims at addressing important issues concerning zinc corrosion and zinc runoff processes of zinc or zinc alloyed with aluminum or magnesium exposed to atmospheric environments. The evolution of the corrosion product (patina) layer is very important for both processes. While corrosion largely is controlled by electrochemical reactions at the metal/patina interface, runoff is predominantly governed by chemical reactions at the patina/atmosphere interface. The gradual evolution of compounds in zinc patina follows one of two main routes: one in more sulfur-dominated and one in more chloride-dominated environments. Because of climatic changes and reduction of sulfur-containing atmospheric species in many parts of the world, the chloride-route is expected to dominate over the sulfur-route. Alloying with aluminum and magnesium results in substantial improvement in corrosion protection, whereby several mechanisms have been proposed. The released amount of zinc is highly dependent on the amount of rainfall, also on sulfur dioxide concentration or deposition, and to only a low extent on chloride deposition. Based on all runoff data, a model is presented which predicts 70% of all observed zinc runoff rates within 40% from their measured value.
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Kumaravel, D., V. K. Bupesh Raja, Kabasker Balthaser, A. Jayaganthan, S. Sahas, S. Muralidharan et Tariku Achamyeleh. « Investigation on Wear and Corrosion Behavior of Cu, Zn, and Ni Coated Corten Steel ». Advances in Materials Science and Engineering 2022 (8 octobre 2022) : 1–9. http://dx.doi.org/10.1155/2022/7341201.
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Corten steel is a low-carbon alloy steel. It is widely used in architecture, the transport sector, and industrial applications, where the steel is exposed to harsh environments. It is very much sought after due to its auto protection from corrosive environments through the formation of patina (rust). The specialty of patina formed on the corten steel is that it can self-heal itself and stop the spreading of corrosion. Generally, steels are given protective coatings to enhance resistance to corrosion, wear, abrasion, etc. One of the popular protective coating techniques is electroplating. In this study, the effect of electroplating of copper (Cu), zinc (Zn), and nickel (Ni) on the wear and corrosion behavior of Corten ASTM A242 grade steel is investigated. It was observed that the Cu coating yielded poor corrosion and wear protection performance. The Zn coating exhibited a moderate improvement. The Ni electroplating produced excellent results and, the wear and corrosion resistance was improved in the corten steel. Thus, when compared with Cu, Zn, and Ni coatings, the Ni-coated corten steel is an ideal candidate in applications where there is a need for good resistance to wear, abrasion, and corrosion.
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Es Sebar, Leila, Leonardo Iannucci, Yuval Goren, Peter Fabian, Emma Angelini et Sabrina Grassini. « Raman investigation of corrosion products on Roman copper-based artefacts ». ACTA IMEKO 10, no 1 (31 mars 2021) : 129. http://dx.doi.org/10.21014/acta_imeko.v10i1.858.
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<p class="Abstract">This paper illustrates a case study related to the characterisation of corrosion products present on recently excavated artefacts. The archaeological findings, from the Rakafot 54 site (Beer-Sheva, Israel), consist of 23 coins and a pendant, all dating back to the Roman period. Raman spectroscopy was used to identify the corrosion products that compose the patina covering the objects. To facilitate and support their identification, spectra were then processed using principal components analysis. This chemometric technique allowed the identification of two main compounds, classified as atacamite and clinoatacamite, which formed the main components of the patinas. The results of this investigation can help in assessing the conservation state of artefacts and defining the correct restoration strategy.</p>
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Mikić, Dajana, Helena Otmačić Ćurković, Tadeja Kosec et Neven Peko. « An Electrochemical and Spectroscopic Study of Surfaces on Bronze Sculptures Exposed to Urban Environment ». Materials 14, no 8 (20 avril 2021) : 2063. http://dx.doi.org/10.3390/ma14082063.
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Polluted urban environment enhances dissolution of patina and underlying bronze material of recent and historical bronze sculptures exposed outdoors. In this work, two bronze statues, situated in one of the most polluted Croatian cities, were examined in order to characterize composition of patina and its electrochemical stability. The composition of patina on several positions on each sculpture was determined by EDS, Raman spectroscopy, and FTIR measurements. Electrochemical impedance spectroscopy measurements were conducted in order to evaluate the corrosion stability of both patina and underlying bronze. Results obtained in this work show that the two examined bronze sculptures were covered with patina layer that was mainly composed of copper sulfides and sulphates, which is in accordance with the high concentrations of H2S and SO2 in the atmosphere. However, the variations in the appearance of FTIR and Raman spectra revealed that the amount of each species differed from spot to spot, as well as the fact that other compounds, such as carbonates, were present at some areas. This difference in patina composition was reflected in electrochemical behavior as observed by electrochemical impedance spectroscopy.
Thèses sur le sujet "Corrosion patina"
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David, Lindström. « Galvanized steel in outdoor constructions - metal runoff, corrosion and patina formation ». Licentiate thesis, KTH, Yt- och korrosionsvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-28615.
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Black, Leon. « A study into the factors influencing the development of patina on the surface of architectural lead ». Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265358.
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Zhang, Xian. « Atmospheric corrosion of zinc-aluminum and copper-based alloys in chloride-rich environments : Microstructure, corrosion initiation, patina evolution and metal release ». Doctoral thesis, KTH, Yt- och korrosionsvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-151180.
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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
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Campos, Pedro Herzilio Ottoni Viviani de. « Estudo e caracterização de pátinas em cobre e bronze com técnicas PIXE e ED-XRF ». Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-01072010-143505/.
Texte intégralRésumé :
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.
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Zavadilová, Petra. « Únavové vlastnosti patinující oceli ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230243.
Texte intégralRésumé :
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.
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Guan, Yong Xiang. « Calcul des coefficients dynamiques du contact patin-pivot d'un palier a patins oscillants ». Lyon, INSA, 1988. http://www.theses.fr/1988ISAL0031.
Texte intégralRésumé :
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.
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Rahmouni, Kamal. « Corrosion et protection des bronzes recouverts de patine : étude électrochimique et spectroscopique de la surface d'objets archéologiques et synthèse d'une patine équivalente sur un bronze du commerce ». Paris 6, 2005. http://www.theses.fr/2005PA066458.
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Vettori, Irene. « Accelerated ageing methodologies for the evaluation of particulate matter role in the corrosion of outdoor-exposed bronzes ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16185/.
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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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SOUZA, Antonio Henrique Tenório de. « Ferramentas computacionais para a análise de dutos com defeitos de corrosão ». Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/5258.
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Previous issue date: 2008Conselho 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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CABRAL, Hélder Lima Dias. « Desenvolvimento de ferramentas computacionais para modelagem e análise automática de defeitos de corrosão em dutos ». Universidade Federal de Pernambuco, 2007. https://repositorio.ufpe.br/handle/123456789/5696.
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Previous issue date: 2007A 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
Livres sur le sujet "Corrosion patina"
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European Commission. Directorate-General XII, Science, Research, and Development., dir. Development of a new non-destructive method for analysis of the atmospheric corrosion and corrosion protection of copper and copper alloys : Protection and conservation of the European cultural heritage. Luxembourg : Office for Official Publications of the European Communities, 1999.
Trouver le texte intégralChapitres de livres sur le sujet "Corrosion patina"
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Edwards, Howell G. M., Peter Vandenabeele et Philippe Colomban. « Patina, Corrosion and Conservation Treatments ». Dans Raman Spectroscopy in Cultural Heritage Preservation, 233–49. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-14379-3_11.
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Dubus, M., S. PagÈS-Camagna, J. Salomon, E. Delange, S. Descamps, M. Aucouturier, D. Robcis, S. Pagès-camagna et F. Mathis. « Corrosion patina or intentional patina ». Dans Corrosion of Metallic Heritage Artefacts. CRC Press, 2007. http://dx.doi.org/10.1201/9781439824054.ch13.
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MATHIS, F., J. SALOMON, S. PAGÈS-CAMAGNA, M. DUBUS, D. ROBCIS, M. AUCOUTURIER, S. DESCAMPS et E. DELANGE. « Corrosion patina or intentional patina : contribution of non-destructive analyses to the surface study of copper-based archaeological objects ». Dans Corrosion of Metallic Heritage Artefacts, 219–38. Elsevier, 2007. http://dx.doi.org/10.1533/9781845693015.219.
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Muller, J., G. Lorang, E. Leroy, B. Laik et I. Guillot. « Electrochemically synthesised bronze patina : characterisation and application to the cultural heritage ». Dans Corrosion of Archaeological and Heritage Artefacts EFC 45, 322–26. Routledge, 2017. http://dx.doi.org/10.4324/9781351192798-2.
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Bunker, Bruce C., et William H. Casey. « Oxide Films in Metal Corrosion : Oxide Defect Chemistry ». Dans The Aqueous Chemistry of Oxides. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780199384259.003.0019.
Texte intégralRésumé :
Most metals used by our society corrode, from the mild tarnish on silver to the green patina that coats our copper statues and electrical wiring to the red rust on our cars and iron bridges (Fig. 12.1, Plate 17). Metal corrosion often involves the conversion of metals into either oxides or their soluble hydrolysis products. The metals we use in our structures, as well as in electronic and magnetic devices, are destroyed as a result of this conversion. It has been estimated that the annual cost of metallic corrosion to the U.S. economy is hundreds of billions of dollars (5% of the gross national product). Therefore, enormous efforts have been made to understand why metals corrode, and what can be done to inhibit corrosion processes. Stainless steel is just one example of humankind’s attempts to limit corrosion processes. Other examples include the use of inert paints on ships to prevent saline corrosion, coating iron with zinc to galvanize it, and exploiting electrochemical strategies, such as using sacrificial anodes that corrode instead of iron, as a means of protecting more important materials’ components. The number of comprehensive texts and reviews regarding metal corrosion scales with its economic impact, with more than 1000 articles being published on the topic per year. Those of you interested in more comprehensive discussions regarding how specific metals corrode in specific environments such as seawater and acid rain should see other works. Our focus in this chapter is to highlight how metal corrosion is mediated by the presence of oxides, with an emphasis on reactions that occur in water. This overview highlights the basic properties of oxide films that give rise to a wide range of complicated metal corrosion phenomena. The discussion draws on many concepts highlighted in other chapters of this book: surface chemistry (Chapter 6), electrochemistry (Chapter 11), and oxide dissolution (Chapter 16). Metal corrosion often involves electrochemical reactions in which the metal is oxidized by either water or O2.
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Aucouturier, M., F. Mathis, D. Robcis, J. Castaing, J. Salomon, L. Pichon, E. Delange et S. Descamps. « Intentional patina of metal archaeological artefacts : non-destructive investigation of Egyptian and Roman museum treasures ». Dans Corrosion of Archaeological and Heritage Artefacts EFC 45, 314–21. Routledge, 2017. http://dx.doi.org/10.4324/9781351192798-1.
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Atkins, Peter. « The Death of Metal : Corrosion ». Dans Reactions. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199695126.003.0012.
Texte intégralRésumé :
As in life, so in redox reactions: some are good and some are bad. Corrosion is one of the evil among redox reactions. It is the unwanted oxidation of a metal that cuts short the lifetimes of steel products such as bridges and vehicles. Replacing corroded metal parts costs industry and society a huge amount each year. Understanding it helps us to find ways to prevent it. Not all corrosion, however, is unwanted: the green patina of copper roofs is often sought and can be beautiful; the induced oxidation of aluminium in the presence of dyes can also be intentional and can bring graceful colour to a building. I shall focus on the corrosion of iron, Fe (from the Latin ferrum), its rusting, as it is so common a way of death for our everyday artefacts. Iron rusts when it is exposed to damp air, with both oxygen and water present. In the process the Fe atoms of the metal are oxidized—lose some electrons—and become Fe3+ ions. These ions pick up some oxide ions, O2–, and are deposited as the red–brown oxide, Fe2O3. The corrosion of iron is very much like its reversion to the ore, which is also typically Fe2O3, from which, with so great an effort and all the expensive and energy-intensive, environmentally invasive fury of a blast furnace, it was originally obtained (Reaction 4). In the process of forming Fe3+, the oxygen of the air, the oxidizing agent, is converted to water. The hydrogen atoms needed for the formation of H2O molecules from O2 molecules are scavenged from the surrounding solution, especially if it is acidic and rich in hydrogen ions. I shall now show you the reaction in more detail and try to lead you into appreciating visually what is going on inside a small droplet of water on the surface of a sheet of rusting iron. Although rusting is rarely thought beautiful, there is a beauty and subtlety in the choreography of the atomic events that underlie its formation. As usual, you should imagine shrinking to the size of a molecule, plunging below the droplet’s surface, and descending diver-like through the densely agitating, bustling, tumbling water molecules.
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Williams, Jonathan, et Andrew Burnett. « A New Gallo-Belgic B Coin Die from Hampshire ». Dans Communities and Connections. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199230341.003.0029.
Texte intégralRésumé :
The die is 18mm in diameter at the business end, and 23mm in length (figure 19.1). It weighs 46.80 grams. On the die-face there is an incuse design of a stylized horse and rider familiar from the coins of the type known as Gallo-Belgic B (figure 19.2). About halfway down the side, it begins to taper towards the other end which is roughly oval in shape, with a longer diameter of 15mm and a shorter one of 13mm. At the base there is a vestigial spike which projects out slightly (figure 19.3). It looks as if it should be an obverse die which would have been set into an anvil or another kind of metal case for striking. However, such evidence as exists for Iron Age dies from northern Europe suggests that, as indeed was the case in the Greek and Roman worlds, reverse dies could either be in the form of a tapered barrel-shaped object set into a metal casing probably made of iron, or in the form of a long metal shaft with the design carved onto the end. The probability, however, is that this example is in fact an obverse die, for reasons outlined below. The die was analysed by Michael Cowell using non-destructive x-ray fluorescence (XRF) on areas where the immediate surface seems to have been removed, and the bulk material exposed. The results should be regarded as semi-quantitative or approximate, as the technique provides only a surface analysis. The following average results were obtained: The die is thus made of a high-tin bronze with small quantities of other metals. Such alloys are extremely hard and difficult to work, for instance by punching or engraving. The die was examined using optical and scanning electron microscopy (SEM). Most of the surface has a dark grey or black-coloured patina, except in a few places around the edge of the die-face and along the side where the surface has been chipped or broken to reveal a light grey crystalline material beneath. The section of the surface patina is exposed here and can be seen to be more than superficial. There are no indications of copper corrosion products (i.e. red cuprite or green malachite).
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Skoulikidis, Th, P. Vassiliou et S. Vlachos. « NEW ANTICORROSIVE PIGMENTS * *Patent # 1000449 Int. C1. C09D 5/08 ». Dans Developments in Marine Corrosion, 132–42. Elsevier, 1998. http://dx.doi.org/10.1533/9781845698768.132.
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Piccardo, P., V. Bongiorno et S. Campodonico. « Artistic patinas on ancient bronze statues ». Dans Corrosion and Conservation of Cultural Heritage Metallic Artefacts, 193–212. Elsevier, 2013. http://dx.doi.org/10.1533/9781782421573.3.193.
Texte intégralActes de conférences sur le sujet "Corrosion patina"
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Zhang, Jingwen, Chenxin Tan et Chunsheng Wang. « Formation mechanism, detection and evaluation of weathering patina on weathering steel bridges ». Dans IABSE Conference, Seoul 2020 : Risk Intelligence of Infrastructures. Zurich, Switzerland : International Association for Bridge and Structural Engineering (IABSE), 2020. http://dx.doi.org/10.2749/seoul.2020.313.
Texte intégralRésumé :
<p>The weathering bridge steel has a lower corrosion rate than low alloy steel bridge, which could produce dense and stable patina on the steel surface, separating the steel substrate from the external corrosion eviroment and preventing the further corrosion. In this paper, the patina of weathering steel for bridge were studied from formation mechanism, evaluation method and patina field and in-suit testing. The formation mechanism and composition of patina was studied, the applicability of detection and evaluation methods of weathering steel bridge were clarified, and the patina stability of weathering steel orthotropic bridge deck and existing bridge in China were evaluated. The purpose of this paper is to provide guidance and selection for the maintenance methods of the patina in the weathering steel bridge.</p>
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Atwood, Sara A., Eli W. Patten, Kevin J. Bozic, Lisa A. Pruitt et Michael D. Ries. « Double-Modular Hip Device Design Susceptible to Stress Corrosion Failure ». Dans ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-204734.
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Total hip replacements restore pain-free mobility to approximately 200,000 patients in the U.S. each year [1]. A typical hip system comprises a metal alloy stem, a femoral head (ceramic or metal alloy), and a polyethylene acetabular cup fit into a metal alloy backing. A modular press-fit Morse taper is commonly used to attach the femoral head to the stem. There are also more recent designs that incorporate a second interface at the neck-stem junction (Figure 1). Increased modularity in total hip replacement design allows the surgeon to intraoperatively preserve patient anatomy such as leg length and femoral anteversion and better balance the surrounding soft tissue for optimal biomechanics. However, modularity also increases the number of mechanical junctions and interfaces in the device which may lead to complications such as corrosion, wear, and fracture.
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Rogers, F. S. « Benefits and Technology Developed to Arc Spray 3/16 Inch (4.8mm) Diameter Wires Used for Corrosion Protection of Steel ». Dans ITSC 2000, sous la direction de Christopher C. Berndt. ASM International, 2000. http://dx.doi.org/10.31399/asm.cp.itsc2000p0691.
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Abstract It has been generally accepted that amperage and voltage are the only variables used to determine spray rate with the twin wire arc spray process. This belief has led to the common practice of defining spray rates in terms of kgs (pounds) per amperes. The "pounds to amperes" theory has been disproved with die advent of equipment capable of successfully arc spraying 4.8 mm (3/16 inch) diameter wires of zinc, aluminum, or 85/15 (zinc/aluminum). Changes in equipment design, that allowed the use of the larger diameter wires, resulted in the issue of a U.S. patent for arc spraying wires over 3.2 mm (1/8 inch) diameter. To achieve production capabilities for spraying 4.8 mm (3/16 inch) diameter wire, numerous problems needed to be solved, which led to additional patent claims.
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Restis, Jude, et Mike Dubberly. « Bolt Hole Corrosion and Fatigue Damage Repair in Hybrid Vertical Lift Structure ». Dans Vertical Flight Society 78th Annual Forum & Technology Display. The Vertical Flight Society, 2022. http://dx.doi.org/10.4050/f-0078-2022-17598.
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Cold expansion has been successfully used in aerospace structures, including vertical lift airframes to repair and prevent fatigue damage for more than 50 years. PartWorks is innovating the cold expansion process, parts and tooling for use in repairing corroded fastener holes (U.S. Patent 11,255,371). PartWorks is participating in a two phase development and demonstration program, first for the US Navy (Office of Naval Research/ONR) starting in 2017, and more recently for the United States Air Force (Air Force Research Lab/AFRL) for repairs to bolt holes on aerospace structures with metal/carbon-fiber composite skins. These locations in aerospace structures for vertical lift or fixed wing have demonstrated greater levels of corrosion when compared to all-metal structural skin due to galvanic corrosion between metal and carbon fiber composites. Existing repair methods for these metal/carbon fiber composite skin bolt hole/fastener sites often involve extensive removal of corrosion, non-standard or oversized holes, and extensive modeling/validation to prove repair effectiveness. Existing repairs can also lead to premature structural component replacement. This project is evaluating a new repair method that uses cold expansion with thin wall bushings and/or a rivetless nut plate (RNP) to restore fatigue life to the metal bolt hole if damage is missed or potentially without having to remove all the damage/corrosion.
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Ibrahim, Hamdy. « A Micro Arc Oxidation Composite Coating Developed on a Biocompatible Magnesium Alloy for Bone Implant Applications ». Dans ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8492.
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Abstract The biocompatibility, mechanical properties and biodegradable nature of Mg alloys have made them attractive for biomedical applications, especially as bone implants. However, one of the main problems that limit the use of Mg alloy for several biomedical applications is their fast corrosion rates inside the body. Coating Mg-based implants is one of the most extensively studied approaches to address the fast corrosion rates of Mg alloys in the physiological environment. Micro arc oxidation (MAO) coating process has shown very promising results towards reducing the corrosion rates of Mg alloys due to the formation of a protective dense, well-adhered and wear-resistant oxide layer on the surface of the Mg alloy. In this study, the feasibility of coating an Mg-Zn-Ca-based alloy with a composite coating made using a micro-arc oxidation coating process and an immersion (dipping process) was investigated. The corrosion properties and surface characteristics of the coated alloy samples are assessed. The created protective composite coating is used to slow the corrosion rates of an Mg-Zn-Ca-based alloy. The developed composite coating resulted in a significant reduction in the corrosion rates. The results of this study show that it is possible to achieve more controlled corrosion rates of Mg-based implants towards patient-specific bone implant applications.
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Andueza, Alejandro, et Segen F. Estefen. « New Algorithm for Full Hexahedral Finite Element Mesh Generation of Pipe Models With Multiple Corrosion Defects ». Dans ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57526.
Texte intégralRésumé :
Analysis of corroded pipelines using simulation techniques has become an essential step for the evaluation of the residual ultimate strength of damaged pipes. Problems with multiple corrosion defects present highly complex geometries mainly when the defects are close enough to produce interacting stress fields. In such cases it is easier the mesh generation with all-tetrahedral elements using mature algorithms implemented in commercial programs like Ansys or Patran. The use of all-tetrahedral meshes in many applications yields to less accurate analysis results. Unfortunately, the algorithm for mesh generation of all-hexahedral elements is much more complex than the generation of all-tetrahedral element mesh. Currently, the problem associated with general all-hexahedral element mesh algorithm is a research subject in progress. This paper presents a new algorithm for the mesh generation of all-hexahedral elements to be used in the analysis of damaged pipelines. The algorithm is currently under development and was designed to deal with any number of corrosion defects of arbitrary shape. The application of the new methodology is demonstrated performing the mesh generation of models with one, two and three corrosion defects in order to demonstrate both efficiency and robustness of the new methodology. Finally, computer simulations for the generated models are performed in order to determine the failure pressure of the damaged pipes. The obtained results are compared to the values predicted by the standard DNV RP-F101.
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Fang, Zhou, Zhiping Chen et Lei Wang. « Study on High-Temperature Naphthenic Acid Corrosion of Type 304 and Type 316L Stainless Steel and Their Welded Joints ». Dans ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77351.
Texte intégralRésumé :
High-temperature naphthenic acid corrosion (HNAC) behaviors of type 304 and type 316L stainless steel have been investigated in the laboratory with the experimental devices, that were designed and built by ourselves and had applied a patent, to evaluate the resistance of the base metal and their welded joints to the HNAC. Corrosion dependencies on the test temperature (ranging 220–320°C), total acid number (TAN) (ranging 1.86–32.0 mg KOH/g) and media physical states (liquid or vapor) were assessed. Specimens after HNAC tests were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. A database of corrosion rates of type 304 and type 316L steel in high-temperature naphthenic acid solution was established. It was found that the HNAC resistance of both type 304 and type 316L degraded rapidly with increasing temperature and TAN. The tests which were conducted simultaneity in liquid media and gas media revealed that both the type 304 and type 316L stainless steel with weld showed worse HNAC compared to the type 304 and type 316L base metal at all temperatures in liquid media, but the difference between them was not obvious. In gas media, the HNAC rates of the type 304 and type 316L stainless steels with welds were greater than those without welds.
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Naylor, Thomas, Roger Black, Cameron Hernandez et Brian D. Jensen. « Relationships Among Band Tension, Sensor Pressure, Patient Comfort, and Puslatile Signal Quality for Wrist Worn Health Monitoring Devices ». Dans ASME 2022 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/detc2022-90637.
Texte intégralRésumé :
Abstract This paper presents the design and testing of a wrist worn health sensing band used to gather relationship data among band tension, sensor pressure, patient comfort, and measured pulsatile signal quality. It uses micromachined carbon-infiltrated carbon nanotube electrodes to detect a patient’s pulse using a bioimpedance approach. The micromachined electrodes experience no corrosion, and they are both strongly conductive and hypoallergenic. A simple mathematical model was developed to show the relationship between pressure on the wrist and tension in the wristband. The wristband was tested by being worn by 10 different research subjects over 15 tests. During each test, the tension in the band was varied, and the tension, pressure, and bioimpedance signal were measured and recorded. The test subject also reported a comfort and pain level score for each level of band tension. The results show that the model correctly predicts that tension varies linearly with pressure, and that the pressure vs. tension slope increases with increasing wrist width. There also exists a linear relationship between tension and patient pain/comfort, but pressure does not show an effect on the patient discomfort or pain experienced. Signal quality when measured in the range of 0–4 N of tension and 0–20 kPa of sensor pressure does not have a direct correlation to either tension or pressure.
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Kobayashi, Y., et S. Yamaguchi. « Development of Thermally Sprayed Coating Applied for Boiler Tube ». Dans ITSC2004, sous la direction de Basil R. Marple et Christian Moreau. ASM International, 2004. http://dx.doi.org/10.31399/asm.cp.itsc2004p0041.
Texte intégralRésumé :
Abstract New composite materials thermally spray powder is developed in order to protect the surface of boiler tube while long period more than up to this time. This powder is so constitute that original sermet is organized from several bolides and inter metallic compounds (patent pending applied for). For the reliable electric power supply, the steam generating boiler is important facility still today. And in boiler operation, one of the most significant problems is the prevention of boiler tube failure. The main destructive processes that ravage boiler tubes are corrosion and erosion. During the last several years, thermally sprayed coating has been applied to the surfaces of boiler tubes. Accordingly, this paper reports on the effects of this developed powder’s coating as compared with these conventional coatings on the prevention of these hot abrasion are tested in laboratory.
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Ocran, Emmanuel, Johnson Aina et Daniel Odoh. « Simulation of the High Strain Rate Deformation Behavior of Titanium Based Alloy for Biomedical Applications ». Dans ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63046.
Texte intégralRésumé :
Human body functions as a network of mechanically coupled parts (components) that work together to form a complete system; these body components can experience failure when in service. Specifically, failure such as arthritis may be caused by articulations at the hip and knee joints. One of such solutions to this failure is the total hip replacement. Materials used in this prosthesis, therefore play an important role in the success of the implant. One of the most commonly used implant material in modern day arthroplasty is the Ti6Al4V alloy, because of its excellent resistance to wear and corrosion in the human body environment. In reality, such implant in service may be subjected to impact loading (at a velocity of about 250–1000m/s), leading to deformation. Typical, examples include an implanted patient involved in an automobile crash and a golf ball hitting an implanted patient at the point of implantation. In this study, the wear and tear resistance property of Ti6Al4V alloy is determined by performing simulation on the high strain rate deformation behavior of IN718 super alloy material and Ti6Al4V plated Inconel material. The maximum stress localized within the plated Inconel material is lesser than that in the unplated material. This shows that Ti6Al4V alloy prevents the localization of stress in the parent Inconel material and is therefore a good wear prevention material, under impact conditions. Also, the impact characterization behavior of Ti6Al4V material is performed in this research in order to determine the maximum stress allowable in the titanium alloy before ultimate failure. Simulation of the high strain rate behavior of the Ti6Al4V alloy is performed at velocities in the range 9–20m/s. It is observed that the localized stress within the Ti6Al4V alloy increases with increased impact velocity. A maximum localized stress is observed in the material beyond which the Ti6Al4V alloy experiences failure. The result of the simulation process helps in determining the maximum impact which an implanted patient can therefore be exposed to and the preventive measures that can be taken in order to guarantee safety of the implanted patient.