Diseño y simulación de un sistema de limpieza y pintura de transformadores.

La principal dificultad es el desperdicio de tiempo provocado por los procesos manuales que actualmente funcionan en la empresa. Los tanques de los transformadores que se arman en la compañía “RVR Transformadores” al ser construidos con chapa de acero requieren de un buen acabado luego de un proceso de pintura; por lo que se vuelve necesario un procedimiento previo de limpieza que sea eficaz en la eliminación de partículas. El proceso actual consiste en la limpieza del material por medio de herramientas manuales y lavado químico, las cuales no son completamente eficientes y requieren de un mayor tiempo dedicado por parte de los operarios solamente a la limpieza. En cuanto a la pintura, ésta se realiza también por procedimiento manual, que en muchas ocasiones presenta fallas las cuales son perceptibles cuando se termina el proceso. Actualmente el proceso completo para la terminación del producto toma mucho tiempo lo que determina un menor número de unidades construidas en los lapsos de trabajo establecidos por la empresa

Pourbaix diagrams for titanium in concentrated aqueous lithium bromide solutions at 25 ºC

Pourbaix diagrams (electrode potential-pH diagrams) for Ti–Br−–H2O system at 25 °C in the absence and presence of titanium hydrides were developed in 400, 700, 850, and 992 g/L LiBr solutions. The diagrams were compared with the simple Ti–H2O system at 25 °C. Comparison of the simple Ti–H2O system with the diagrams of the Ti–Br−–H2O system at 25 °C showed that the titanium solubility range in the acid, neutral, and weak alkaline areas of the diagrams extended slightly to both higher pH values and potentials with increasing bromide ion activity and decreasing water activity.The authors acknowledge the MICINN (Ministerio de Ciencia e Innovacion, Convention No. CTQ2009-07518) and FEDER (Fondo Europeo de Desarrollo Regional) for the support of this work, Dr. M. Asuncion Jaime for her translation assistance, and Antonio Juncos for his assistance in plotting the diagrams.Muñoz Portero, MJ.; García Antón, J.; Guiñón Segura, JL.; Leiva García, R. (2011). Pourbaix diagrams for titanium in concentrated aqueous lithium bromide solutions at 25 ºC. Corrosion Science. 53(4):1440-1450. https://doi.org/10.1016/j.corsci.2011.01.013S1440145053

In-Situ Study of Corrosion Evolution of Alloy 926 (UNS N08926) in its Unsensitised and Sensitised State in LiBr Solutions Using Confocal Laser Scanning Microscopy

The aim of this work is to study the corrosion evolution of a unsensitised and sensitised stainless steel in a 992 g/l LiBr solution. The tested material has been a highly alloyed austenitic stainless steel (UNS N08926) in its as-received state and heated at 825 degrees C for 1 hour in an inert atmosphere. Tests have been carried out in an electrochemical minicell that can be put in the stage of a confocal microscope. Differences in the evolution of morphology attack have been observed between the unsensitised and sensitised samples. The used technique has demonstrated to be very useful to check differences in the evolution of corrosion processes.Leiva García, R.; Muñoz Portero, MJ.; García Antón, J. (2012). In-Situ Study of Corrosion Evolution of Alloy 926 (UNS N08926) in its Unsensitised and Sensitised State in LiBr Solutions Using Confocal Laser Scanning Microscopy. ECS Transactions. 41:1-10. doi:10.1149/1.3692434S1104

Effect of Volcano-Polluted Seawater on the Corrosion Behaviour of Different Alloys

During a subsea volcano eruption, gases and thermal water emissions are released. This might change the behaviour of the materials that are in contact with the seawater caused by the decrease of the pH value. For this reason, the materials for marine applications are selected to maintain the integrity of the structure and to be corrosion resistant. In spite of this, corrosion can cause great damage to marine steel infrastructures such as bridges, wharfs, platforms and pipeline systems. These corrosion problems could be aggravated if the medium is altered, due to volcano emissions, since the resistance of the surface film is influenced by the environmental conditions

Electrochemical behavior during the zirconium conversion coating formation on AISI 1006 steel

This study investigated a conversion coating based on hexafluorozirconic acid solution on cold-rolled (AISI 1006) steel sheets, in situ, at different pH values and immersion times. Electrochemical characterization was carried out by electrochemical impedance spectroscopy (EIS) with hexafluorozirconic acid bath as the electrolyte. Laser scanning confocal microscopy (LSCM) was used to evaluate the morphology of the coating in situ, i.e., during the coating formation. According to the results, the polarization resistance (Rp) of the conversion coating is affected by the immersion time and by the pH of the conversion bath. The electrochemical analyzes point out conversion baths at pH between 3.5 and 4.5 and immersion times from 600 to 900 s as optimal operating conditions, achieving an average polarization resistance of 713 ± 107 Ω cm2

Influence of sensitisation on the corrosion behaviour of Alloy 926 (UNS N08926) in concentrated aqueous lithium bromide solutions at different temperatures

[EN] The aim of this work is to study the influence of sensitisation to intergranular corrosion on a highly alloyed austenitic stainless steel, Alloy 926 (UNS N08926). Some specimens of this steel have been heated in an argon atmosphere at 825 degrees C during 1 hour. The degree of sensitisation has been characterised by means of SEM, etching (with oxalic acid), and electrochemical reactivation methods (single and double loop tests). The corrosion behaviour of sensitised and unsensitised Alloy 926 has been analysed in a concentrated aqueous lithium bromide (LiBr) solution of 992 g/L by means of cyclic potentiodynamic curves at different temperatures. The results indicate that chromium carbide precipitates reduce the pitting potential value of Alloy 926. Besides, the pitting potential decreases with temperature. On the other hand, the corrosion potential and open circuit potential values increase with temperature and sensitisation.We wish to express our gratitude to MICINN (CTQ2009-07518), to FEDER, to Dr. Helena Alves from Krupp VDM for supplying the materials, and to Dr. Asunción Jaime for her translation assistance.Leiva García, R.; Muñoz-Portero, M.; Garcia-Anton, J. (2011). Influence of sensitisation on the corrosion behaviour of Alloy 926 (UNS N08926) in concentrated aqueous lithium bromide solutions at different temperatures. International Journal of Electrochemical Science. 6(2):442-460. http://hdl.handle.net/10251/61141S4424606

In-Situ Study of Single and Double Loop Reactivation Methods During the Characterisation of the Degree of Sensitisation of a Duplex Stainless Steel (UNS 1.4462) Using a Minicell and a Confocal Microscope

[EN] The aim of this work is to study the evolution of the electrode surface during the single and double reactivation methods at microscopic scale. The tested material has been a duplex stainless steel (UNS 1.4462) in its as-received state and heated at 825 degrees C for 1 hour in an inert atmosphere. Tests have been carried out in an electrochemical minicell that can be put in the stage of a confocal microscope. These devices allow the in-situ observation of the electrode surface at microscopic scale during the tests. Differences in the evolution of the electrode surface have been observed between the single and the double loop methods. Furthermore, the sensitised sample shows different evolution during the electrochemical tests than the as-received sample. These differences are due to the formation of new phases during the heat treatment. Therefore, the minicell permits obtaining additional information during the electrochemical characterisation of the degree of sensitisation in duplex stainless steels.We wish to express our gratitude to MICINN (CTQ2009-07518), to FEDER, to the Generalitat Valenciana for its help in the CLSM acquisition (MY08/ISIRM/S/100), and to Dr. Asunción Jaime for her translation assistance.Leiva García, R.; Muñoz-Portero, M.; Garcia-Anton, J. (2011). In-Situ Study of Single and Double Loop Reactivation Methods During the Characterisation of the Degree of Sensitisation of a Duplex Stainless Steel (UNS 1.4462) Using a Minicell and a Confocal Microscope. International Journal of Electrochemical Science. 6(3):830-846. http://hdl.handle.net/10251/61142S8308466

Improvement of the electrochemical behaviour of Zn-electroplated steel using regenerated Cr(III) passivation baths

Conversion coatings based on trivalent chromium are more sensitive to the presence of zinc and iron impurities than the chromate formulations. This fact contributes to a decrease in the quality of passivation and to the generation of a significant amount of hazardous liquid waste. Recently, a new eco-innovative process based on Emulsion Pertraction Technology (EPT) is being implemented at industrial scale for selectively removing Zn and Fe from spent passivation baths in order to enhance the lifetime of the Cr (III) baths. In this study, the effect of Zn and Fe removal on the electrochemical behaviour of Zn-electroplated steel samples was evaluated by means of polarisation curves and electrochemical impedance spectroscopy measurements at open circuit potential conditions in 3.5 g/L NaCl solutions. The main objective was to assess the benefits brought by EPT using electrochemical methods. Cr (III) passivation baths regenerated using the EPT process have been compared to the bath used in a local industry as well as to fresh and spent baths. According to the results, the samples passivated in the EPT regenerated bath showed a significant improvement in their electrochemical behaviour compared to the samples passivated in the spent baths. This study concluded the suitability of EPT for regenerating Cr (III) passivation baths

Ansiedad competitiva y clima motivacional en jóvenes futbolistas de competición, en relación con las habilidades y el rendimiento percibido por sus entrenadores

En este estudio se analizan las relaciones existentes entre la ansiedad competitiva (en sus facetas cognitiva y somática) y el clima motivacional percibido (de ego y de maestría) en una población de 54 jóvenes futbolistas decompetición de edad media de 9,45 años, respecto de la percepción de sus habilidades y rendimiento deportivos por parte de sus 4 entrenadores, que también participaron en el estudio. Para ello se les administró las versiones españolas del SAS-2 (Sport Anxiety Scale-2, Smith, Smoll, Cumming y Grossbard, 2006) y el MCSYS (Motivational Climate Scale for Youth Sports,Smith, Cumming y Smoll, 2008), así como dos escalas ad hoc para evaluar la percepción de su habilidad y rendimiento. Los resultados muestran, por una parte, que los jóvenes futbolistas perciben y discriminan claramente los climas motivacionales, que se distribuyen casi al 50% entre ego y maestría; por otra, que aparece ansiedad competitiva, aunque más cognitiva que somática, y que no existe relación significativa con las percepciones de habilidad y rendimiento por parte de los entrenadores. Finalmente, estos resultados se discuten y se comparan con otros similares en poblaciones preadolescentesThis study analysed the relationships between competitive anxiety (both cognitive and somatic) and perceived motivational climate (ego and mastery) in 54 young competitive soccer players (mean age: 9.45 years), related to their four coaches' perceptions of the soccer players' skills and performance. We administered the Spanish versions of the SAS-2 (Sport Anxiety Scale-2, Smith, Smoll, Cumming and Grossbard, 2006) and the MCSYS (Motivational Climate Scale for Youth Sports, Smith, Cumming and Smoll, 2008), along with two ad hoc scales to evaluate perceived skills and performance.The results show that 1) young players perceived and discriminated clearly between motivational climates (which were more or less equally distributed between ego and mastery orientations), 2) some performance-related anxiety (mostly cognitive rather than somatic) appeared and 3) no significant relationships were found between their coaches' perceptions of their skills and their performance. Lastly, the results are discussed and compared with similar results from preadolescent player