Browsing by Keyword "Alumina"
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Item Numerical Modeling of the Influence of Nanometric Ceramic Particles on the Nucleation of AlSi10MnMg Alloy(2022-05-17) Jimenez, Ane; Sanchez, Jon Mikel; Girot, Franck; Renderos, Mario; Egizabal, Pedro; CIRMETAL; Tecnalia Research & InnovationIn recent years, many researchers have attempted to model the solidification process of nano-reinforced materials. In the present document, the effect on the heterogeneous solidification regime of the different sizes, shapes, and chemical compositions of nanometric ceramic particles in an AlSi10MnMg alloy is studied. This article develops a mathematical model to predict the solidification behavior of a general nano-reinforced alloy, then validates the results using experimental techniques. The main objective of the model is to minimize the costly and time-consuming experimental process of fabricating nano-reinforced alloys. The proposed model predicts the critical Gibbs energy and the critical radius required for nucleation in the heterogeneous solidification regime. Conversely, the experimental part focuses on understanding the solidification process from the differential thermal analysis (DTA) of the solidification curves. It was concluded that if subcooling is involved, cubic and pyramidal particles work better as nucleating particles in the studied alloy.Item Pore flow-through catalytic membrane reactor for steam methane reforming: characterization and performance(2022-07-12) Angulo, M.; Agirre, I.; Arratibel, A.; Llosa Tanco, M. A.; Pacheco Tanaka, D. A.; Barrio, V. L.; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSA series of pore flow-through catalytic nonselective membrane reactors (PTCMRs) were studied for steam methane reforming (SMR) in the 500 to 900 °C temperature range under 10 barg pressure and a steam-to-carbon ratio of 5. The reactants flow through the pores of the membrane where they react on contact with the Pd nanoparticles. Various reactor configurations were prepared and tested with porous α-Al2O3-based ceramic tubes with one or more γ-Al2O3/YSZ layers on the external surface. The palladium content and dispersion affect the catalytic activity of the reactors and the results show that the efficiency of the reactions depends on the number of γ-Al2O3/YSZ layers.Item Preparation and characterization of metallic supported thin Pd–Ag membranes for hydrogen separation(2016-12-01) Fernandez, Ekain; Medrano, Jose Antonio; Melendez, Jon; Parco, Maria; Viviente, Jose Luis; van Sint Annaland, Martin; Gallucci, Fausto; Pacheco Tanaka, D. A.; TECNOLOGÍAS DE HIDRÓGENO; Tecnalia Research & Innovation; EXTREMAT; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThis paper reports the preparation and characterization of thin-film (4–5 μm thick) Pd–Ag metallic supported membranes for high temperature applications. Various thin film membranes have been prepared by depositing a ceramic interdiffusion barrier layer prior to the simultaneous Pd–Ag electroless plating deposition. Two deposition techniques for ceramic layers (made of zirconia and alumina) have been evaluated: Atmospheric Plasma Spraying and dip coating of a powder suspension. Initially, the prepared ceramic layers have been characterized for nitrogen permeation at room temperature and surface roughness for the selection of the appropriate type of ceramic layer. The most promising membranes have been tested at 400–600 °C for single gas permeation (H2 and N2), and have shown extremely high H2/N2 permselectivities (>200,000).