Corrosión por nido de hormigas de tubos de cobre utilizados en sistemas de aire acondicionado

15 pages, 12 figures, 3 tables.[EN] Ant-nest corrosion is a specific type of premature failure (2-3 months) of copper tubes used in air-conditioning units causing the loss of refrigerant liquid and the consequent environment pollution. It is known that attack requires the simultaneous presence of moisture, oxygen and a corrodent, usually an organic acid, such as formic, acetic, propionic or butyric acid or other volatile organic substances like methanol, ethanol, formaldehyde or acetoaldehyde. Approximately 10% of all premature failures of copper tubes used in the heating, ventilation and air-conditioning (HVAC) industry are the result of ant-nest corrosion. This type of corrosion usually occurs in thin-wall copper pipes, especially when copper is de-sulphurised, and is known by several names: formicary corrosion, unusual corrosion, branched pits, pinhole corrosion, etc.[ES] Corrosión por “nido de hormigas” es un tipo específico de fallo prematuro (2-3 meses) que tiene lugar en tubos de cobre utilizados en sistemas de aire acondicionado originando la pérdida de líquido refrigerante y la consecuente contaminación ambiental. Es conocido que este tipo de ataque requiere la presencia simultánea de humedad, oxígeno y un medio agresivo, habitualmente un ácido orgánico, como fórmico, acético, propiónico o butírico u otras sustancias orgánicas volátiles tales como metanol, etanol, formaldehido o acetoaldehido. Aproximadamente el 10% de los fallos prematuros en tubos de cobre utilizados en calefacción, ventilación y en la industria de aire acondicionado son el resultado de corrosión por nido de hormigas. Frecuentemente, este tipo de corrosión tiene lugar en tubos de cobre de pared delgada, especialmente cuando el cobre es del tipo desulfurizado, y se conoce con varios nombres: corrosión por ácido fórmico, corrosión no habitual, picaduras ramificadas, corrosión con forma de alfiler, etc.The authors express their gratitude to the International Copper Association (ICA) Ltd. (New York) and to the Centre for Advanced Interdisciplinary Research in Materials (CIMAT) (Chile) for financial support under Project No. TEK-1023-9.Peer reviewe

Corrosión por nido de hormigas de tubos de cobre utilizados en sistemas de aire acondicionado

15 pages, 12 figures, 3 tables.[EN] Ant-nest corrosion is a specific type of premature failure (2-3 months) of copper tubes used in air-conditioning units causing the loss of refrigerant liquid and the consequent environment pollution. It is known that attack requires the simultaneous presence of moisture, oxygen and a corrodent, usually an organic acid, such as formic, acetic, propionic or butyric acid or other volatile organic substances like methanol, ethanol, formaldehyde or acetoaldehyde. Approximately 10% of all premature failures of copper tubes used in the heating, ventilation and air-conditioning (HVAC) industry are the result of ant-nest corrosion. This type of corrosion usually occurs in thin-wall copper pipes, especially when copper is de-sulphurised, and is known by several names: formicary corrosion, unusual corrosion, branched pits, pinhole corrosion, etc.[ES] Corrosión por “nido de hormigas” es un tipo específico de fallo prematuro (2-3 meses) que tiene lugar en tubos de cobre utilizados en sistemas de aire acondicionado originando la pérdida de líquido refrigerante y la consecuente contaminación ambiental. Es conocido que este tipo de ataque requiere la presencia simultánea de humedad, oxígeno y un medio agresivo, habitualmente un ácido orgánico, como fórmico, acético, propiónico o butírico u otras sustancias orgánicas volátiles tales como metanol, etanol, formaldehido o acetoaldehido. Aproximadamente el 10% de los fallos prematuros en tubos de cobre utilizados en calefacción, ventilación y en la industria de aire acondicionado son el resultado de corrosión por nido de hormigas. Frecuentemente, este tipo de corrosión tiene lugar en tubos de cobre de pared delgada, especialmente cuando el cobre es del tipo desulfurizado, y se conoce con varios nombres: corrosión por ácido fórmico, corrosión no habitual, picaduras ramificadas, corrosión con forma de alfiler, etc.The authors express their gratitude to the International Copper Association (ICA) Ltd. (New York) and to the Centre for Advanced Interdisciplinary Research in Materials (CIMAT) (Chile) for financial support under Project No. TEK-1023-9.Peer reviewe

Corrosión de Al, Cu, Fe y Zn en atmósferas controladas

Tesis - Universidad Complutense de Madrid, 1981.Fac. de Ciencias QuímicasTRUEProQuestpu

Corrosión y protección de metales para la construcción y el patrimonio cultural

4 páginas, 2 figuras. Ed. Miguel Ángel Rogerio Candelera y Cesáreo Sáiz Jiménez. Primera Reunión de la Red de Ciencia y Tecnología para la Conservación del Patrimonio (Madrid, 28-29 de junio de 2011).La corrosión, es decir, la reacción química del metal con el medio en que se encuentra, es la principal causa de degradación del patrimonio cultural metálico. La naturaleza y estructura del material metálico, y el medio en el que se encuentra (sea el medio atmosférico exterior o interior de un museo o vitrina; el agua del mar o la tierra en los objetos sumergidos o enterrados; o incluso componentes de otra naturaleza que forman parte del propio objeto) condiciona los mecanismos y velocidad de deterioro. Es por lo tanto fundamental, si queremos asegurar correcta conservación de este patrimonio metálico, conocer los mecanismos por los que se produce este deterioro y desarrollar metodologías y estrategias para su protección, especialmente adaptadas a las características y necesidades peculiares de este tipo de objetos.Peer reviewe

Electrochemical characterization of organic coatings for protection of historic steel artefacts

Figuras en el archivo zipElectrochemical techniques are mainly known in the field of cultural heritage conservation as a tool for the elimination of corrosion layers or the removal of chlorides. However, these techniques are also a valuable tool for assessing the anti-corrosive efficiency of protective coatings. The aim of this study was to evaluate the performance of different coatings for their use in metallic heritage conservation using polarization resistance (Rp) and electrochemical impedance spectroscopy (EIS). Carbon steel samples were prepared to simulate the surface composition and morphology of historic steel artefacts, and coated by a conservator-restorer following the common practices in conservation treatments. Three commercial organic coatings have been studied: a microcrystalline wax (RenaissanceTM) and a methyl acrylate/ethyl methacrylate copolymer resin (ParaloidTM B-72) dissolved in acetone –both them commonly used in conservation and restoration treatments– and a ethylene copolymer wax emulsion in water (PoligenTM ES- 91009), that has not been used so far for this purposes. Four commercial corrosion inhibitor additives were added to the ParaloidTM B-72 resin and PoligenTM ES-91009 wax. The additives were commercial preparations with the following known active components: a blend of triazoles (M435), an ammonium salt of tricarboxylic acid (M370), a calcium sulphonate (M109), and a bis-oxazoline (Alkaterge-TTM). Rp and EIS results showed that the best protection of the steel specimens was afforded by PoligenTM ES-91009 when applied in thick layers. None of the additives have shown a clear improvement of the protection properties of the coatings, and one of them impaired the barrier effect of the coating.Acknowledgements The authors express their gratitude to the Sixth Framework Programme of the European Commission for financial support of PROMET Project (Contract 509126). D.M. Bastidas expresses his gratitude to the CSIC of Spain for his contract under the I3P Programme, co-financed by the European Social Fund.Peer reviewe

Improved in vitro angiogenic behavior on anodized titanium dioxide nanotubes

[Background] Neovascularization over dental implants is an imperative requisite to achieve successful osseointegration onto implanted materials. The aim of this study was to investigate the effects on in vitro angiogenesis of anodized 70 nm diameter TiO2 nanotubes (NTs) on Ti6Al4V alloy synthesized and disinfected by means of a novel, facile, antibacterial and cost-effective method using super oxidized water (SOW). We also evaluated the role of the surface roughness and chemical composition of materials of materials on angiogenesis.[Methods] The Ti6Al4V alloy and a commercially pure Ti were anodized using a solution constituted by SOW and fluoride as electrolyte. An acid-etched Ti6Al4V was evaluated to compare the effect of micro-surface roughness. Mirror-polished materials were used as control. Morphology, roughness, chemistry and wettability were assessed by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy (EDX) and using a professional digital camera. Bovine coronary artery endothelial cells (BCAECs) were seeded over the experimental surfaces for several incubation times. Cellular adhesion, proliferation and monolayer formation were evaluated by means of SEM. BCAEC viability, actin stress fibers and vinculin cellular organization, as well as the angiogenic receptors vascular endothelial growth factor 2 (VEGFR2) and endothelial nitric oxide synthase (eNOS) were measured using fluorescence microscopy.[Results] The anodization process significantly increased the roughness, wettability and thickness of the oxidized coating. EDX analysis demonstrated an increased oxygen (O) and decreased carbon (C) content on the NTs of both materials. Endothelial behavior was solidly supported and improved by the NTs (without significant differences between Ti and alloy), showing that endothelial viability, adhesion, proliferation, actin arrangement with vinculin expression and monolayer development were evidently stimulated on the nanostructured surface, also leading to increased activation of VEGFR2 and eNOS on Ti6Al4V-NTs compared to the control Ti6Al4V alloy. Although the rougher alloy promoted BCAECs viability and proliferation, filopodia formation was poor.[Conclusion] The in vitro results suggest that 70 nm diameter NTs manufactured by anodization and cleaned using SOW promotes in vitro endothelial activity, which may improve in vivo angiogenesis supporting a faster clinical osseointegration process.The authors wish to thank to the Program Number UABC-PTC-469 from PRODEP and Program Number 2058 of UABC for financial support. They are also grateful to CONACYT, Mexico, for scholarship 348737-114359.Peer reviewe

A Raman spectroscopy study of steel corrosion products in activated fly ash mortar containing chlorides

8 pags.; 9 figs.; 3 tabs.Raman spectroscopy was used to characterise the corrosion products of reinforcing steel embedded in activated fly ash mortars in the presence of 0.4% and 2% chlorides. Two alkaline solutions with different soluble silica contents were utilised to activate the fly ash. Raman spectra were obtained using two excitation wavelengths (532 and 633 nm) and making power scans to select the suitable conditions of register for each wavelength. The main steel corrosion products identified were iron oxyhydroxides with low crystallinity, goethite (a-FeOOH) and lepidocrocite (c-FeOOH). These products need to be studied using a spectrometer with the laser line of 532 nm at low powers from 0.025 to 0.25 mW or a spectrometer with the laser line of 633 nm at high power between 2.5 and 25 mW. 2015 Elsevier Ltd. All rights reserved.M. Criado expresses her gratitude to the Spanish Ministry of Science and Innovation for her Juan de la Cierva contract (Ref. JDC-2010). The authors express their gratitude to Project BIA2008-05398 from CICYT, Spain, for financial support. European Community and Comunidad de Madrid for supporting two Geomateriales programs S2013/MIT- 2014Peer reviewe

Corrosion of Reinforced Concrete Structures

Corrosion of reinforced concrete structures is nowadays one of the major concerns on the durability and serviceability of buildings and constructions. Corrosion management and monitoring of infrastructure and civil engineering structures are required to guarantee their lifetime in service. Current society demands for new materials; diagnosis techniques and computational modeling then can contribute to increase corrosion resistance, thus improving safety and extending the service lifetime of reinforced concrete structures. Sustainability of reinforced concrete structure is crucial for better social development because of the importance of structural safety, preservation of environment, and economy. In developed countries, corrosion economic losses due to maintenance, repair, and replacement of existing structures and infrastructure account for up to 4% gross domestic product (GDP). It is worth to note that production of new materials not only is costly but also requires a large amount of energy consumption, which dramatically influences greenhouse effect because of CO2 emissions.As guest editors, we would like to especially thank Jonathan Wood, review operations specialist, for his support and active role in the publication. We are also grateful to the entire staff of the Frontiers in Materials Editorial Office for the precious collaboration

Cleaning of two hundred year-old copper works of art using citric acid with and without benzotriazole and 2-amino-5-mercapto-1,3,4-thiadiazole

This paper studies the use of 5% (wt) citric acid without inhibitor, inhibited with benzotriazole (BTA) and 2-amino-5-mercapto-1,3,4thiadiazole (AMT) and de-aerated with nitrogen in the cleaning of 18th and 19th century chalcographie plates. DC and AC electrochemical techniques have been used to characterize the effect of the inhibitors and to quantify the aggressiveness of the cleaning treatment. Citric acid removes copper surface tarnish. BTA and AMT inhibitors are similarly efficient. De-aeration reduces corrosion to levels similar to those obtained with inhibitors. © VCH Verlagsgesellschaft mbH, 1996.Peer Reviewe