Aluminum-silicon coatings on austenitic stainless steel (aisi 304 and 317) deposited by chemical vapor deposition in a fluidized bed

Se obtuvieron recubrimientos de aluminio-silicio en los aceros inoxidables AISI 304 y AISI 317. La deposición se realizó a 540 °C, con una proporción de gases activos (HCl/H2: 1/15.3), como gas de arrastre se utilizó argón. El lecho del proceso CVD-FBR estaba formado por 2,5 g de polvo de aluminio, 7,5 g polvo de silicio y 90 g de alúmina. Después de depositados los recubrimientos, se le dio un tratamiento térmico para mejorar sus propiedades mecánicas y su comportamiento frente a la oxidación, por entre la difusión de los elementos de aleación. La simulación termodinámica se realizó con el software Thermo-Calc para obtener información sobre la posible composición del material depositado. Las muestras recubiertas y sin recubrir, se expusieron a 750 º C en una atmósfera donde el vapor se transporta a las muestras usando un flujo de N2 de 40 ml / min y 100% de vapor de agua (H2O). Aceros recubiertos ganaron algo de peso durante las mil horas de exposición y resisten muy bien el ataque corrosivo frente a los sustratos recubiertos. Además, los aceros inoxidables recubiertos muestran una velocidad de oxidación con tendencia logarítmica, mientras que la velocidad de oxidación de acero sin recubrimiento tiene tendencia lineal.Aluminum-silicon coatings were deposited onto stainless steels AISI 304 and AISI 317. The deposition was performed at 540°C with a ratio of active gases HCl/H2 of 1/15.3; argon was used as a carrier gas. The bed of the FBR-CVD process consisted of 2.5 g aluminum powder, 7.5 g silicon powder and 90 g alumina. After the coatings were deposited, each sample was given a heat treatment to improve its mechanical properties and oxidation behavior by diffusing the alloying elements. Thermodynamic simulation was performed with Thermo-Calc software to investigate the composition of the deposited material. The coated and uncoated specimens were exposed to temperatures of 750ºC in an atmosphere where the vapor was transported to the samples using a flow of N2 of 40 ml/min and 100% water vapor (H2O). The coated specimens gained little weight during the thousand hours of exposure and will thus guard against a corrosive attack compared to the uncoated substrates. In addition, the coated stainless steels show an oxidation rate with a logarithmic trend while the uncoated steel oxidation rate showed a linear trend

Aerial Robotic Solution for Detailed Inspection of Viaducts

The inspection of public infrastructure, such as viaducts and bridges, is crucial for their proper maintenance given the heavy use of many of them. Current inspection techniques are very costly and manual, requiring highly qualified personnel and involving many risks. This article presents a novel solution for the detailed inspection of viaducts using aerial robotic platforms. The system provides a highly automated visual inspection platform that does not rely on GPS and could even fly underneath the infrastructure. Unlike commercially available solutions, our system automatically references the inspection to a global coordinate system usable throughout the lifespan of the infrastructure. In addition, the system includes another aerial platform with a robotic arm to make contact inspections of detected defects, thus providing information that cannot be obtained only with images. Both aerial robotic platforms feature flexibility in the choice of camera or contact measurement sensors as the situation requires. The system was validated by performing inspection flights on real viaducts.Unión Europea H2020-2019-769066Unión Europea H2020-2020- 87154

Evaluación del daño por carburización de un tubo retirado de servicio de un horno de pirólisis

Hydrocarbon pyrolysis is a process characterized by carried out for long periods at temperatures above 843° C and environment highly reducing. These severe conditions contribute to deterioration by carburización of the coils of the furnaces which carries out the process of thermal breakage by pyrolysis of hydrocarbons. In this work it was evaluated the damage state of a section of the coil in the radiant zone of a pyrolysis furnace of ethane to ethylene production. This tube was removed from service by coking. Further analysis of Electronic Scanning Microscopy, metallographies, chemical composition analysis, hardness and microhardness, allowed to evaluate and to establish the state of damage by carburizing.La pirólisis de hidrocarburos es un proceso que se caracteriza por llevarse a cabo durante largos períodos de tiempo a temperaturas superiores a los 843° C y atmósferas altamente reductoras. Dichas condiciones severas contribuyen al deterioro por carburización de los serpentines de los hornos en donde ocurre el proceso de rotura térmica por pirólisis, de los hidrocarburos. En este trabajo, se evaluó el estado de daño de un tramo de serpentín de la zona radiante de un horno de pirólisis de etano para la producción de etileno. El tubo fue retirado del servicio del horno de pirólisis debido a la coquización presente en su interior. Posteriores análisis de Microscopia Electrónica de Barrido, análisis metalográfico, análisis de composición química, análisis de dureza y microdureza, permitieron evaluar el estado de daño por carburización

Mesh size and effort changes in multispecies fisheries in ICES Divisions Vlllc and IXa.

Different simulations varying trawl mesh size and effort changes for several fishing units in ICES Divisions VIllc and IXa were carried out. Landings included in the analysis represent most of the catches in the southern area defined as the management unit for hake, megrim; monkfish, horse mackerel, blue whiting and mackerel. Three Nephrops stock s in Divisions Vlllc and IXa are also included. These species are mainly exploited by Spanish and Portuguese fleets, using various fishing gears to exploit different fractions of the populations, and for this reason nine fishing units were used in the analysis

Experimental study on steam oxidation resistance at 600 °C of Inconel 625 coatings deposited by HVOF and laser cladding

Inconel 625 (IN625) coatings were deposited by High-Velocity Oxy-fuel (HVOF) and laser cladding, on a 10.50–12%Cr steel to improve its oxidation resistance. Both as-deposited coatings exhibited a γ-Ni-Cr matrix and two protective oxides (Cr2O3 and NiCr2O4). In addition, laser cladding as-deposited coatings also presented precipitates A2B-type Laves phases due to the dilution effect from laser cladding technique. Coated and uncoated steel were oxidized under isothermal conditions at 600 ◦C for 2000 h and subsequently analyzed using gravimetry, SEM-EDS and XRD techniques. The application of IN625 coatings revealed a weight gain ten times lower than that registered for the uncoated steel, this improvement being mainly due to the presence of protective and stable Cr2O3 and NiCr2O4 oxides. Additionally, the XRD analysis showed that the initial Laves phases present in the laser cladding coating, were re-dissolved and transformed in δ-Ni3Nb compound suggesting that that the temperature and exposure time are enough to induce this transformation

Defective lysosomal proteolysis and axonal transport are early pathogenic events that worsen with age leading to increased APP metabolism and synaptic Abeta in transgenic APP/PS1 hippocampus

Background: Axonal pathology might constitute one of the earliest manifestations of Alzheimer disease. Axonal dystrophies were observed in Alzheimer’s patients and transgenic models at early ages. These axonal dystrophies could reflect the disruption of axonal transport and the accumulation of multiple vesicles at local points. It has been also proposed that dystrophies might interfere with normal intracellular proteolysis. In this work, we have investigated the progression of the hippocampal pathology and the possible implication in Abeta production in young (6 months) and aged (18 months) PS1(M146L)/APP(751sl) transgenic mice. Results: Our data demonstrated the existence of a progressive, age-dependent, formation of axonal dystrophies, mainly located in contact with congophilic Abeta deposition, which exhibited tau and neurofilament hyperphosphorylation. This progressive pathology was paralleled with decreased expression of the motor proteins kinesin and dynein. Furthermore, we also observed an early decrease in the activity of cathepsins B and D, progressing to a deep inhibition of these lysosomal proteases at late ages. This lysosomal impairment could be responsible for the accumulation of LC3-II and ubiquitinated proteins within axonal dystrophies. We have also investigated the repercussion of these deficiencies on the APP metabolism. Our data demonstrated the existence of an increase in the amyloidogenic pathway, which was reflected by the accumulation of hAPPfl, C99 fragment, intracellular Abeta in parallel with an increase in BACE and gamma-secretase activities. In vitro experiments, using APPswe transfected N2a cells, demonstrated that any imbalance on the proteolytic systems reproduced the in vivo alterations in APP metabolism. Finally, our data also demonstrated that Abeta peptides were preferentially accumulated in isolated synaptosomes. Conclusion: A progressive age-dependent cytoskeletal pathology along with a reduction of lysosomal and, in minor extent, proteasomal activity could be directly implicated in the progressive accumulation of APP derived fragments (and Abeta peptides) in parallel with the increase of BACE-1 and gamma-secretase activities. This retard in the APP metabolism seemed to be directly implicated in the synaptic Abeta accumulation and, in consequence, in the pathology progression between synaptically connected regions