Browsing by Author "Arteche, A."
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Item Bioenergía: Producción de biocombustibles líquidos: Últimas tendencias en la aplicación de la biotecnología industrial(2012-03) Roncal, T.; Gómez, O.; Arteche, A.; Pérez, S.; Belsué, M.; BIOECONOMÍA Y CO2; Mercado; VALORIZACIÓN DE RESIDUOS; Tecnalia Research & InnovationItem The effect of the addition of carbon nanotubes in the hydrothermal synthesis and in the thermal phase stability of nanozirconia(2010-04) Garmendia, N.; Arteche, A.; García, A.; Bustero, I.; Obieta, I.; Mercado; PRINTEX; Tecnalia Research & InnovationThe yttria partially stabilized zirconia is a very attractive material for orthopaedic applications. It exhibits excellent biocompatibility, high fracture toughness, high strength and low wear rates. But case studies show that delayed failure can occur in vivo due to crack propagation. Carbon nanotubes could avoid the slow crack propagation and enhance the toughness of the ceramic material used for prostheses fabrication. In this work, X-ray diffraction has been used to study the influence of the addition of MWCNT on the hydrothermal synthesis of tetragonal zirconia nanoparticles and on the phase stability of the CNT-nanozirconia nanocomposite with the temperature. First, the influence of the processing variables on the hydrothermal synthesis has been studied. The theoretical mathematical models that relate the percentage of tetragonal zirconia nanocrystals and the relative crystallinity with the processing variables in the range of analyzed values have been obtained. The values that give the maximum percentage and crystallinity of tetragonal phase in the studied range have been established. No significant differences were observed in the crystalline phases obtained when adding MWCNT during the synthesis. Nanozirconia partially coated MWCNT synthesized under the optimized parameters were added to commercially available nanozirconia particles and their influence in the phase stability of the zirconia with the temperature was studied by XRD. It was concluded that the addition of the carbon nanotubes delays both the monoclinic phase decomposition and the grain growth.Item Recovery «in situ» of EAFD metals by means of process INTECT in the laboratory and pilot plant experimentations(2005) Solozabal, R.; Arteche, A.; Kanari, N.; Gaballah, I.; Ugarte, A.; Tecnalia Research & Innovation; MercadoThis paper summarizes the INTECT process devoted to the recovery of valuable elements from electric arc furnace dust 'EAFD' «in - situ». Acidic leaching of EAFD, separation of solid/liquid, cementation of obtained ZnCl2 solution, precipitation of hydroxy-carbonate, calcinations of Zn5(CO3)2(OH)6 to obtain ZnO were successful tasks on the laboratory and pilot plant scales. The electrodialysis unit for NaCl splitting, to generate NaOH and HCI, was successful on the laboratory scale, its scaling up to the pilot scale was half success. Manufacturing of 400 tons of briquettes devoted to the study the impact of recycling of leaching's solid residue in the electric arc furnace was successful. Results of industrial trials confirm that including briquettes up to 2% of the charge of EAF doesn't modify the quality of the produced steel. The off gases' chemical composition was almost identical to that of normal operations. Moreover, the physico-chemical characteristics of the dust and the slag weren't modified. In addition, the generated dust had a higher content of Zn and there were no modifications of working conditions. Environmental assessment of the INTECT process is positive since recycling of EAFD will allow the conservation of mineral and energetic resources and will contribute indirectly to lower the CO2 emission.Item XRD study of the effect of the processing variables on the synthesis of nanozirconia in the presence of MWCNT(2009-02) Garmendia, N.; Arteche, A.; García, A.; Bustero, I.; Obieta, I.; Mercado; PRINTEX; Tecnalia Research & InnovationSeveral challenges must be solved to obtain an effective introduction of carbon nanotubes in a ceramic matrix. Dispersion, good load transfer, and wettability are the major issues to be overcome to obtain good final properties of a zirconia nanocomposite. We have developed a process to coat multi-wall carbon nanotubes with nanozirconia to deal with these challenges. The process is based on the hydrothermal synthesis of tetragonal zirconia nanoparticles in the presence of multi-wall carbon nanotubes (MWCNT). In this work, X-ray diffraction has been used to study the influence of the processing variables in order to optimize this process. The theoretical mathematical models that relate the percentage of tetragonal zirconia and their crystallinity in relation to the processing variables have been extracted.