Corrosion of light alloys. Semi-solid processing, Nd addition and advanced anodizing treatments

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, leída el 25/05/2016. Tesis formato europeo (compendio de artículos)La política medioambiental de la Unión Europea ha impuesto una serie de restricciones que afectan de forma directa a la industria del transporte. Así por ejemplo en automoción, ha limitado la cantidad de emisiones de gases de combustión en vehículos ligeros de pasajeros (95 g CO2/km para el 2020). Además ha establecido un listado de compuestos químicos potencialmente dañinos para la salud y medioambiente que deben ser retirados antes de 2018. Entre ellos se encuentran el ácido crómico, componente básico de los electrolitos empleados en el anodizado de aleaciones de aluminio en la industria aeronáutica. Estas limitaciones presentan un gran desafío para la industria del transporte, ya que debe ser capaz de encontrar nuevos materiales y tratamientos superficiales alternativos a los procesos actuales con el fin de alcanzar los requerimientos exigidos en un plazo relativamente corto de tiempo. Dada la relación directa que existe entre el consumo y la masa del vehículo, no es de extrañar que una de las medidas tomadas por los principales fabricantes de automóviles sea la sustitución de materiales tradicionales, como el acero, por otros más ligeros. El aluminio y el magnesio son los más ligeros de los metales estructurales. Esto, unido a las excelentes propiedades que presentan sus aleaciones y a su buena reciclabilidad, los sitúa como candidatos excepcionales para su empleo en automoción y, en general, en la industria del transporte. Desde el punto de vista de la resistencia a la corrosión, las propiedades del aluminio puro son excelentes, sin embargo la incorporación de elementos aleantes necesarios para mejorar el comportamiento mecánico pueden reducir considerablemente su resistencia a la corrosión debido, entre otras razones, a la formación fases secundarias de diferente naturaleza electroquímica. El magnesio puro y sus aleaciones presentan una elevada susceptibilidad a la corrosión en medios agresivos debido a su propia naturaleza activa y su poca tendencia a la formación de películas pasivas de carácter protector. Por tanto, es habitual recurrir al empleo de tratamientos superficiales cuando se pretende garantizar una duradera vida en servicio de las aleaciones comerciales de aluminio y magnesio...The European Union environmental policy has resulted in a number of restrictions that directly affect the transport industry. For instance, in the automotive industry, the total emissions of combustion gases from passenger vehicles have been limited to 95 g CO2/km by 2020. Additionally, a list of potentially dangerous chemicals that must be removed from the market before 2018 has been established. Chromic acid, which is the main component of electrolytes used for anodising in aircraft, has been included in this list. These limitations are a great challenge for the transport industry since new materials and alternative surface treatments should be developed in order to meet the requirements in a relatively short period of time. Since weight and fuel consumption are directly related, vehicle manufacturers have chosen to replace traditional materials such as steel, for lighter ones. Aluminium and magnesium are the lightest among the structural materials, have excellent properties and are easily recycled. These advantages make them particularly interesting for the transport industry. From the corrosion point of view, aluminium behaviour is outstanding; however the addition of alloying elements for improving its mechanical properties may reduce its corrosion resistance due to the formation of electrochemically active secondary phases, among other factors. Magnesium and its alloys are highly susceptible to corrosion in aggressive environments due to their active nature and to its low tendency to form passive layers. Thus, surface treatments are a common practice in those applications where it is intended to maximize the working life of the material...Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEunpu

El clima de aula. Un factor decisivo en el aprendizaje de lenguas

[spa] Se ha propuesto una guía didáctica para realizar en sesiones de euskera que profundice en el conocimiento mutuo entre los alumnos para que se fomente así la creación de vinculos interpersonales basados en el diálogo, la negociación y la comprensión. Todo ello supone la generación de un ambiente de aula cálido en el que todos los alumnos (gitanos y no gitanos) se sientan respetados, reconocidos y valorados, lo que garantiza el desarrollo óptimo y el acercamiento de los alumnos a la segunda lengua[eus] Elkarrizketan, negoziazioan eta elkar ulertzean oinarritutako pertsona arteko harremanen sorrera sustatzeko ikasleen arteko elkar ezagutzean sakontzen duen gida didaktikoa, euskara saioetan garatuko dena, proposatu da. Horren ondorioz, ikasleak (ijitoak eta ez ijitoak) errespetatuta, aintzatestuta, eta baloratuta sentituko diren gelako giro egokia sortuko da. Horrek bigarren hizkuntzaren garapena eta ikasleen artean hizkuntzarekiko interesa pistea bermatuko du.[eng] We had proposed a teachers' book to be developed in Basque in which the students can get a better knowledge of each other so that through a good comunication, negotiation and understanding they can create strong interpersonals bonds. All this would create a warm atmosphere in the class where all the students -Roma and not Roma- feel respected and appreciated, which would also guarantee the best evolution of the language and would boost the students’ interest for this second language

Operational use of SEVIRI and other satellite enhancements at AEMET

Presentación realizada en: 3rd ACCORD ASW celebrado del 27 al 31 de marzo de 2023 en Tallin, Estonia

Layered Double Hydroxide Coatings Loaded with Corrosion Inhibitors for Corrosion Protection of AZ31 †

Layered double hydroxide (LDHs) coatings were developed for the corrosion protection of AZ31 Mg alloy. AZ31 is widely used in the transport industry due to its low mass density and good mechanical properties. LDH coatings were fabricated under co-precipitation conditions and applied under hydrothermal conditions. Two different systems Zn-Al LDH and Li-Al LDH were studied. Specimens were post-treated via immersion for 2 h at 45 °C in inhibitor aqueous baths. Na2WO4·H2O and LiNO3 inorganic inhibitors were used, respectively, to produce inhibitor-loaded systems: Zn-Al LDH(W) and Li-Al LDH(Li). The characterization of the coatings was carried out by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The corrosion process was studied by electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). The surface was also evaluated via the determination of water drop contact angle and the performance of a paint adhesion test using an epoxy primer. The characterization of the coating revealed two-layered coatings with a denser inner layer and a flaky outer layer. Both coatings improved the corrosion resistance of the AZ31 alloy. Loading with inhibitor further increased the corrosion resistance by one order of magnitude (bare substrate, Z10mHz~102 Ω cm2; LDH, Z10mHz~103–4 Ω cm2; LDH-inhibitor, Z10mHz~105 Ω cm2).Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEFEDER/Ministerio de Ciencia e Innovación−Agencia Estatal de InvestigaciónComunidad de MadridMinisterio de Ciencia, Innovaciónpu

The Host Galaxies of Hybrid Morphology Radio Sources

Based on their differing radio morphologies, powerful radio galaxies can be separated into the Fanaroff–Riley I (FR I) and II (FR II) classes. Hybrid morphology radio sources (HyMoRS) contain morphologies consistent with each type of jet on either side: a powerful, highly relativistic FR I–like jet terminating in a hotspot on one side and an FR I–like plume on the other. HyMoRS present a unique opportunity to study the conditions that give rise to the dichotomy. Using host galaxy properties, we conduct the first multiwavelength investigation into whether orientation can explain HyMoRS morphology. Through optical spectroscopy and mid-infrared photometry, we analyze the emission characteristics, and evaluate the broad characteristics of five HyMoRS host galaxies at intermediate redshifts (0.4 < z < 1.5). The HyMoRS host galaxies in our sample have properties consistent with typical host galaxies of FR II sources, suggesting that the observed hybrid morphologies may be caused by a dense, cluster-like environment bending FR II jets combined with a favorable orientation that can make one side appear similar to an FR I jet. Our results thus support the hypothesis that HyMoRS are mainly caused by environment and orientation

Effects of pre-anodizing and phosphates on energy consumption and corrosion performance of PEO coatings on AA6082

A significant reduction in the energy consumption of Plasma Electrolytic Oxidation (PEO) coatings on AA6082 alloy was obtained using strategies based on electrolyte selection and a precursor anodic film. PEO coatings were developed on AA6082 in silicate-based electrolytes with different phosphate species without and with a precursor oxide layer. The electrical response and, therefore, the specific energy consumption depended on the phosphate species and most notably on the applied pretreatment. The best result was obtained after anodic pretreatment and PEO in silicate-polyphosphate electrolyte with a reduction up to ⁓66% in comparison with the most conventional treatment (direct PEO in orthophosphate electrolyte). The corrosion response is not affected significantly by the pre-anodizing treatment either for short or prolonged immersion times revealing that coatings synthesised under high-energy efficient conditions have comparable corrosion performance under aggressive corrosive environments compared to conventional PEO processes