Browsing by Keyword "Hydrothermal synthesis"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item 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 Synthesis of zeolite type analcime from industrial wastes(2020-02) Vigil de la Villa Mencía, Raquel; Goiti, Eunate; Ocejo, Marta; Giménez, Rosario García; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNA range of industrial wastes (recycled glass, silica fume, siliceous concrete waste aggregates, sterile coal and foundry sand from the steel industry) are employed in the formation of secondary raw materials following their hydrothermal treatment. Composed mainly of zeolites, these secondary materials, in almost all cases, formed analcime. The sterile coal yielded the best defined analcime crystals. In addition, the secondary raw materials are incorporated as an addition in cement paste formulations, to evaluate their effect at early stages of the hydration process. The secondary materials from the siliceous concrete waste aggregates and recycled glass produced a 23% increase in the compressive strength of the paste after 1 day of curing (in comparison with the cement paste reference).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.