Examinando por Autor "Palacio C.C."
Mostrando 1 - 3 de 3
Resultados por página
Opciones de ordenación
Ítem Comparison of TiO2 targets manufactured by APS and sintering processes for PAPVD coatings suitable in technological and medical applications(ASM International, 2018-01-01) Jaramillo Raquejo D.; Palacio C.C.; Ageorges H.; Jaramillo Raquejo D.; Palacio C.C.; Ageorges H.; Universidad EAFIT. Departamento de Ciencias; Electromagnetismo Aplicado (Gema)In surface science of functional oxides, Titanium dioxide (TiO2) is one of the most investigated crystalline systems either in rutile or anatase phases. Rutile phase is widely used in microelectronic, tribological applications and in the conversion of solar energy. Anatase phase is used in self-cleaning, antifogging, photo-catalytic and biomedical technologies. This work focuses on studying the required process conditions to obtain TiO2 targets by APS onto metallic substrates using commercial TiO2 powders (Oerlikon Metco in Switzerland) with suitable physical and chemical properties for technological and medical applications as PAPVD coatings. APS targets were compared to sintered ones. The raw powders were characterized by laser diffraction, SEM, XRF and XRD while the characteristics of the APS-deposited targets as well as the sintered ones were determined by SEM and XRD to identify the constituent phases. This work allowed confirming the advantages and limitations of both processes in terms of grain size, chemical composition, microstructural homogeneity and density in order to choose the best option to manufacture targets for PAPVD coatings for technological and medical applications. © 2018 ASM International® All rights reserved.Ítem Pelletisation by tumbling as an alternative method of agglomerating nanometric particles for use as feedstock in bi-modal structured flame-sprayed ceramic coatings(Elsevier Ltd., 2019-01-01) Árias J.A.; Hurtado F.M.; Estrada G.; Cadavid E.; Rincón Ortiz M.; Palacio C.C.; Vargas F.; Universidad EAFIT. Departamento de Ciencias Básicas; Electromagnetismo Aplicado (Gema)This paper is focused on the physical evaluation of ceramic granules of Al2O3, Al2O3-13 wt% TiO2 (AT-13) and TiO2 obtained from alumina and titania nanoparticles by pelletisation in a rotating drum. The results were compared with those of both sintered and non-sintered granules of similar chemical compositions and particle size distributions which were spray dried, as well as with those of TiO2 pelletised granules blended with atomised alumina particles. The results obtained indicated that the physical characteristics of the pelletised granules conferred them a free-flowing behavior which was similar to that of the spray-dried granules. However, the TiO2 pelletised granules blended with harder atomised alumina particles disintegrated and, therefore, exhibited a poor flowability. Additionally, it was evident that the ceramic coatings fabricated from pelletised granules displayed a structure which was as or more compact than those of the granules obtained from agglomerated powders by spray drying with or without sintering, apart from being more compact than that of the coatings deposited from TiO2 pelletised granules blended with atomised alumina particles. The above findings indicate that the alternative pelletising method is potentially useful for the use of agglomerated nanoparticles as feedstock in the fabrication of bi-modal structured flame-sprayed ceramic coatings. © 2019 Elsevier Ltd and Techna Group S.r.l.Ítem Study of APS and conventional sintering parameters for the manufacture of TiO2 targets for PAPVD(IOP PUBLISHING LTD, 2019-01-01) Jaramillo Raquejo D.; Palacio C.C.; Ageorges H.; Jaramillo Raquejo D.; Palacio C.C.; Ageorges H.; Universidad EAFIT. Departamento de Ciencias; Electromagnetismo Aplicado (Gema)In surface science of functional oxides, titanium dioxide (TiO2) is one of the most investigated crystalline systems either in rutile or anatase phases. In this work commercial TiO2 powders are used to study the required process conditions to obtain TiO2 targets by Atmospheric Plasma Spray (APS) and conventional sintering, with suitable physical and chemical properties to be source material for Plasma Assisted Physical Vapor Deposition (PAPVD) for technological and medical applications. Two three factor Box Behnken experimental designs combined with surface modeling were employed to estimate the influence of spraying parameters (gun current, Ar/H2 ratio and standoff distance) and sintering parameters (heating rate, sintering temperature and holding time) within the targets microstructure (cracks and pores in cross section) and phases composition. The microstructure and composition of APS-deposited targets and sintered ones were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The lowest defects percentages of the targets manufactured in this work were 0.41 ± 0.30 % for APS-deposited targets and 0.05 ± 0.04 % for the sintered ones using the optimal parameters suggested by the statistical model, which allowed confirming the advantages of sintering process and limitations of APS in terms of microstructural homogeneity, but also of the use of design of experiments in the modeling of systems of many variables when there is not diagnostic equipment of the processes available. © Published under licence by IOP Publishing Ltd.