Browsing by Author "Onate, J. I."
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Item Implantation d'azote dans les aciers a outils.(1989) Onate, J. I.; Dennis, J. K.; Hamilton, S.; Tecnalia Research & InnovationThis article originally appeared in the journal 'Heat Treatment of Metals' (UK) 1987, no. 3, p.77-82. In certain cases, ion implantation can constitute a replacement for and in others a complement to, conventional surface treatments or similar processes which aim to increase properties such as wear resistance, fatigue and corrosion resistance and surface hardners. The principles, merits and dements of the process are reviewed and the article focuses specifically on the implantation of nitrogen, which is the most frequently used element for treating plastic moulds. (C.J.A.)Item Interaction of engineered surfaces with the living world: Ion implantation vs. osseointegration(2007-08-05) Braceras, I.; Alava, J. I.; Goikoetxea, L.; de Maeztu, M. A.; Onate, J. I.; Biomateriales; Tecnalia Research & InnovationThe reaction of living tissues to foreign materials is a highly complex process that currently is insufficiently understood. Nevertheless, if specific reactions are to be promoted, this understanding is highly valuable and thus a significant research effort is being devoted to this issue. Typically, when a biomaterial is inserted in living tissue, proteins and other bio-molecules will adsorb to the surface. As this protein layer will mediate the interaction of the biomaterial with the living world, the consequent reactions will be highly dependant on this very first stage. Furthermore, different materials, i.e. surfaces, typically elicit a very different tissue response. It is commonly admitted that the primary adsorption depends heavily on the surface chemistry, surface topography and surface physical characteristics. Interactions between surface micro-topography and living cells have been widely studied, but protein specific reactions versus nano-topography have been barely explored. Ion beam modification of surfaces, which affect these key properties, can therefore be (i) a powerful tool to advance in the understanding of these nanoscale phenomena and (ii) useful as an industrial treatment of high value-added medical devices. This work will explore the application of ion beam based surface treatments to cause specific reactions in hard tissue regeneration. A variety of in vitro and in vivo results are presented corresponding to ion implantation treatments promoting "osseointegration" or intimate binding between the biomaterial and the living tissue, without any soft tissue interlayer, and an overview of the mechanism behind is offered, i.e. among other behaviour of osteoblasts, signalling proteins as the integrins, nanotopographic parameters.Item Micromechanical properties of diamond films deposited by microwave-plasma-enhanced chemical vapour deposition(1993-04-13) Garcia, A.; Flaño, N.; Viviente, J. L.; Onate, J. I.; Gomez-Aleixandre, C.; Sanchez-Garrido, O.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationThis paper reports on the study of mechanical properties of diamond films produced by microwave plasma chemical vapour deposition on silicon under different deposition conditions. The quality of films has been examined by scanning electron microscopy, Raman spectroscopy and Auger electron spectroscopy. Raman and Auger electron spectra show significant differences between the sp3 and sp2 bonding characters depending on the methane concentrations used in the deposition of diamond films. The microstructure of these films has a significant influence on the microhardness and elastic properties measured by a dynamic microindentation technique in a load range 0.4-10 mN. Changes in film quality have shown variations in these values, leading to a relationship between the microstructure and mechanical properties of these diamond films. The best results have been obtained for diamond films deposited at CH4 concentrations in H2 of less than 0.5 vol.%, reaching hardness values of up to 42 GPa and percentages of elastic recovery of up to 84.5%.Item NITROGEN IMPLANTATION OF TOOL STEELS.(1987) Onate, J. I.; Dennis, J. K.; Hamilton, S.; Tecnalia Research & InnovationIn certain circumstances, ion implantation offers an alternative or an addition to traditional surface heat treatments and other processes aimed at improving properties such as resistance to wear, fatigue and corrosion, and surface hardness. In this article, the authors review the principle of the process, its advantages and limitations, some of the properties conferred, and the applications. The emphasis is on implantation with nitrogen, the element most commonly used in the treatment of plastic molding dies, cold-work tools and engineering components. The process is also applicable to plated coatings.Item Wear-resistant metal-carbon composite coating(2000-06-01) Uglov, V. V.; Kuleshov, A. K.; Rusalsky, D. P.; Onate, J. I.; Yang, Si Ze; Tecnalia Research & InnovationCarbon coatings containing a metallic component (zirconium, tantalum) were deposited with ion assistance on AISI M2 steel samples using a SVETLYACHOK source. The coatings were studied by Auger electron spectroscopy (AES), transmission electron microscopy (TEM), Raman spectroscopy (RS) and pin-on-disc tribological tests. The results have shown that the carbon coatings contain up to 20 at.% of the metallic component. These coatings have an amorphous structure with sp3-type bonds. The presence of the coating on the surface of AISI M2 steel reduces the friction coefficient by a factor of five under the tribological conditions investigated. It is found that the tribological properties of the coatings deposited with the assistance of metal ions are significantly better than those coatings deposited with assistance of carbon ions. The latter coatings had carbon atoms with mixed sp3-sp2 bonds. The deposited composite carbon coatings are stable at a temperature of 100°C and allow a twofold improvement in the lifetime of fuel pump rods. (C) 2000 Elsevier Science S.A. All rights reserved.