Browsing by Author "Onate, J.I."
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Item Bone cell adhesion on ion implanted titanium alloys(2005-06-22) Braceras, I.; Onate, J.I.; Goikoetxea, L.; Viviente, J.L.; Alava, J.I.; de Maeztu, M.A.; Tecnalia Research & Innovation; Biomateriales; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe authors have previously reported than ion implantation can have a significant effect on osseointegration of an implant, specially when the latter is introduced in areas of poorer bone density. These results indicate that this process is particularly suited for implant devices introduced in elderly patients or in those regions that have a poor quality of bone. The aim of this work is directed to study osteoblast adhesion on Ti alloy surfaces with different ion implantation treatments, so osseoconductive properties of several surfaces can be assessed. Polished discs of Ti–6Al–4V and Ti CP GR1 titanium alloy have been prepared and ion implanted with different species and parameters (dose and energy). Afterwards, the samples have been sterilized by UV light, inoculated with 1.5×105 human bone cells and incubated during 4 h at 37 C and 5% CO2 atmosphere. Then, once fixed and rinsed, image analysis has been used to quantify the number of cells attached to the Ti discs. On a second round of tests, cell proliferation tests have been conducted during 24, 48, 144 and 192 h, respectively. Furthermore, surface analysis techniques (e.g. AFM) have been applied to learn about the qualitative behavior, i.e. morphology, of the attached cells. Cell attachment has shown to be highly sensitive to ion implantation parameters. Although some quantitative differences have been observed, the more significant differences were qualitative. AFM analysis has shown that the star-shaped bone cells attached spread more and occupied larger surfaces like in osseointegration prone surfaces, most probably due to extracellular matrix synthesized around them, while other surfaces showed mainly large and narrow shaped or round shaped bone cells often with great cellular nucleus in the middle of the cells and little extracellular matrix around. So, ion implanted surfaces that facilitate osseointegration have been identified, in terms of initial bone cell attachment quality, where although the number of attached cells were not necessarily always larger, they tended to occupy wider areas with healthier cells.Item Characterization of nanostructured Ti–B–(N) coatings produced by direct current magnetron sputtering(2007-02-26) López-Cartes, C.; Martínez-Martínez, D.; Sánchez-López, J.C.; Fernández, A.; García-Luis, A.; Brizuela, Marta; Onate, J.I.; TECNOLOGÍAS DE HIDRÓGENO; INGENIERÍA DE SUPERFICIES; Tecnalia Research & InnovationA series of Ti–B–(N) coatings prepared by dc magnetron sputtering using TiB2 targets in Ar/N2 gas mixtures has been chemically and structurally characterized by transmission electron microscopy, X-ray diffraction, electron energy-loss spectroscopy, and X-ray photoelectron spectroscopy. The influence of synthesis parameters such as applied heating power and nitrogen flow on the structure and chemical composition of the coatings has been studied. Independently of the experimental conditions employed during the synthesis, hexagonal TiB2 is the main crystalline phase present in the coatings. The use of N2 leads to the formation of an amorphous mixture of BN/TiN phases, as well as a diminution of the TiB2 crystalline phase. The influence of the composition and structure of the coatings on their hardness is also discussed.Item Effects of ion implantation on nano-topographic properties(2007-08-05) Braceras, I.; Briz, N.; García, F.; Muñoz, R.; Viviente, J.L.; Onate, J.I.; INGENIERÍA DE SUPERFICIES; SG; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationIt is well known that surface properties at nano-scale are determinant in a number of applications, such as sensors, biomedical and optical devices. Nevertheless, relations between surface treatment parameters and their effects on topography at the nano-scale, surface energy or light reflectivity are often poorly understood. In this study, a non fluorescent glass material (Knittel) was selected and subjected to ion implantation treatments with different parameters and species, including Ar, Ne, C, N, CO and NH2. The resulting surface topography at the nano-scale was studied by Atomic Force Microscopy (AFM) and the surface energy was evaluated with the contact angle method. Additionally, the modifications induced on optical properties, i.e. reflection, were evaluated with two different wavelength lasers. The results showed remarkable differences in surface nano-topographies and contact angles (from 15° to 70°) that were obtained. Furthermore, the effects of ion implantation parameters had also very significant consequences on background noise effects, of great importance for optical properties. It was found that the best implantation treatment corresponded to N2 + ions implanted to a dose of 3×1017 ions/cm2 at an energy of 30 keV. This treatment resulted in a adequate contact angle, producing a nano-textured surface with potential features for a good attachment and orientation of deposited bio-molecules, and a very low background fluorescence, hence allowing a high degree of scanning sensitivity, for application on DNA microarrays. The study has shown that ion implantation represents a powerful tool for modifying key properties on surfaces that play an important role in the response elicited on living tissue and bio-molecules, which is notoriously relevant for the application as bio-sensors.Item Improved osseointegration in ion implantation-treated dental implants(2002-09) Braceras, I.; Alava, J.I.; Onate, J.I.; Brizuela, Marta; García-Luis, A.; Garagorri, N.; Viviente, J.L.; de Maeztu, M.A.; Oate, J. I.; INGENIERÍA DE SUPERFICIES; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSImplants for knee, hip and dental part replacement are becoming increasingly used in surgery. Unfortunately, their use is sometimes accompanied by failure due to infection, inflammation, integration problems with the surrounding tissues or bone, and implant failure due to mishandling. Surface treatment, such as ion implantation, has been identified as a good candidate to modify the surface properties of the implant to significantly improve its osseointegration. This work reports on the ion implantation of light ions in commercial Ti6Al4V dental implants and subsequent osseointegration tests. Various light ions were implanted (C, N, CO, Ne) with energy ranging from 45 to 100 keV and doses up to 5×10e17 ions/cm2. Both ion-implanted and control dental implants were inserted in the tibial plateau of adult rabbits, the epiphysis and diaphysis of the tibia for the evaluation of their degree of osseointegration. After 3 months the implants were extracted and several histological sections were prepared from whole bones for evaluation of their osseointegration in the tibia. In addition, the surface of the implant, and the interface between the bone and the implant were examined by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques. Some ion implantation treatments did not significantly change the performance of the dental implants relative to the untreated implants, while tests showed that the ion implantation of CO remarkably improved the osseointegration properties, i.e. the percentage of bone and implant in contact.Item Magnetron sputtering of Cr(Al)N coatings: Mechanical and tribological study: Mechanical and tribological study(2005-10-01) Brizuela, Marta; García-Luis, A.; Braceras, I.; Onate, J.I.; Sánchez-López, J.C.; Martínez-Martínez, D.; López-Cortés, C.; Fernández, A.; López-Cartes, C.; INGENIERÍA DE SUPERFICIES; TECNOLOGÍAS DE HIDRÓGENO; Tecnalia Research & InnovationCrN coatings produced by magnetron sputtering are routinely deposited on tools and components for machining and forming applications. This paper reports on the effect of additions of aluminium (<15 at.%) on the mechanical and tribological properties of CrN coatings. Aluminium has been incorporated into CrN by co-sputtering of chromium and aluminium in a mixture of argon and nitrogen. Mechanical properties have been evaluated by ultramicroindentation techniques and scratch testing, while tribological tests have been carried out against ball bearing steel and titanium alloy balls by the pin-on-disc method. The thermal stability and oxidation resistance of the coatings have also been examined. A significant increase in hardness, reaching values up to 35 GPa, has been achieved for the CrAlN coatings when compared to CrN coatings. The improvement in tribological properties has also been remarkable, with a decrease in friction coefficient against bearing steel and also a non-adhesive wear mechanism against titanium alloy balls. In addition, the CrAlN coatings exhibited higher thermal stability than pure CrN coatings.Item Mechanical behavior and oxidation resistance of Cr (Al) N coatings(2005-06-21) Sánchez-López, J.C.; Martínez-Martínez, D.; López-Cartes, C.; Fernández, A.; Brizuela, Marta; García-Luis, A.; Onate, J.I.; INGENIERÍA DE SUPERFICIES; TECNOLOGÍAS DE HIDRÓGENO; Tecnalia Research & InnovationNanocrystalline chromium nitride and ternary chromium aluminium nitride thin films were deposited by reactive magnetron sputtering of Cr and Al targets in argon/nitrogen atmosphere varying the sputtering power and gas composition. The coatings were characterized in terms of crystal phase, chemical composition, microstructure, and mechanical properties by x-ray diffraction, x-ray photoelectron spectroscopy, including x-ray-induced Auger electron spectroscopy, transmission electron microscopy, selected-area electron diffraction, electron energy-loss spectroscopy, cross-sectional scanning electron microscopy, and ultramicrohardness tester. The incorporation of Al in the composition of the films produces an increase in the mechanical properties (hardness and reduced Young's modulus) and an increased thermal resistance against oxidation in comparison to the pure CrN composition. The hardness behavior was attributed mainly to a reduction of the CrN crystallite size according to a Hall-Petch relationship. The oxidation resistance was evaluated after annealing both types of coatings in air up to 800 degrees C. The oxygen content and the crystallite size appear almost unaltered in the CrAIN in contrast to the pure CrN films where the oxidation and grain growth is very noticeable at 800 degrees C. This improvement in thermal stability in air is explained by the formation of a nanocomposite structure of small CrN crystals embedded in an amorphous aluminum oxide or oxinitride matrix that prevents the CrN phase from crystal growth and further oxidationItem Mechanical properties of nanocrystalline Ti–B–(N) coatings produced by DC magnetron sputtering(2005-10-01) García-Luis, A.; Brizuela, Marta; Onate, J.I.; Sánchez-López, J.C.; Martínez-Martínez, D.; López-Cartes, C.; Fernández, A.; TECNOLOGÍAS DE HIDRÓGENO; INGENIERÍA DE SUPERFICIES; Tecnalia Research & InnovationTi–B–(N) coatings have been deposited by DC magnetron sputtering using TiB2 targets in Ar/N2 gas mixtures. The influence of bias voltage and nitrogen flow on the mechanical and tribological properties of these coatings has been studied. Mechanical properties have been evaluated by ultra-microindentation techniques and scratch testing; tribology tests have been performed in a pin-on-disc apparatus with controlled humidity conditions. Microstructural characterization by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) demonstrates the nanocrystalline structure of Ti–B–(N) coatings and allows the interpretation of their mechanical behaviour. Hardness values up to 58 GPa have been achieved, depending on deposition conditions. Increasing the bias voltage on the substrates improves the hardness of coatings, while the addition of nitrogen significantly decreases these values. Coating adhesion obtained on highspeed steel is very good in most cases, reaching values higher than 60 N of critical load. Tribotests performed on these coatings against a Steel contact (wear conditions: 0.98 N load, 10 cm/s, 50% RH, 10 mm bearing steel ball diameter) have yielded very low wear rates but friction coefficients in the range of 0.6–1.0.Item MoSx lubricant coatings produced by PVD technologies(2007-03-01) Onate, J.I.; Brizuela, Marta; Viviente, J.L.; García-Luis, A.; Braceras, I.; Gonzalez, D.; Garmendia, Iñaki; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIES; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; TECNOLOGÍAS DE HIDRÓGENOAmong the different options for solid lubrication, MoS2 is probably the most attractive due to its extremely low friction levels. Recent developments in magnetron sputtering physical vapour deposition (PVD) technology have allowed the development of MoS2 composite thin films with more compact structures, low friction behaviour and enhanced wear resistance, reducing degradation by humidity. The present work provides an overview of recent developments in dry lubrication with MoS2 films deposited by modern sputtering PVD and how these MoS2 films alloyed with Ti or WC can outperform conventional unalloyed films not only under vacuum but also under atmospheric high humidity conditions. MoSx–WC composite films outperform MoSx–Ti films, showing endurance at 0·75 GPa as high as 1·2 million wear cycles, also significantly higher than the values obtained from unalloyed, conventional MoS2 thin solid films. The films also exhibit a steady state friction coefficient from 0·02 to 0·04. In addition, these films also show resistance to humid environment when tested under atmospheric conditions.Item Tailored synthesis of TiC/a-C nanocomposite tribological coatings(2005-10-25) Martínez-Martínez, D.; López-Cartes, C.; Justo, A.; Fernández, A.; Sánchez-López, J.C.; García-Luis, A.; Brizuela, Marta; Onate, J.I.; TECNOLOGÍAS DE HIDRÓGENO; INGENIERÍA DE SUPERFICIES; Tecnalia Research & InnovationComposite coatings made of nanocrystalline TiC (nc-TiC) particles and amorphous carbon (a-C) have been prepared in a double magnetron sputtering system using graphite and titanium targets under Ar bombardment. Chemical composition and microstructure of coatings were studied by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and x-ray diffraction (XRD) for a set of samples prepared varying the ratio and intensity of power applied to each magnetron. Changes in coatings microstructure, from a quasipolycrystalline TiC to a nanocomposite formed by nanocrystals of TiC embedded in an amorphous matrix of carbon (nc-TiC/a-C), are observed depending on the synthesis conditions. Tribological and mechanical properties of coatings were tested using a pin-on-disk tribometer and an ultramicrohardness indenter, respectively. Coatings with moderate hardness (7-27 GPa), low friction (0.1-0.2), and low wear rates (k similar to 10(-7) mm(3)/N m) were obtained. A percentage between 15% and 30% of TiC is found as an optimum value to get a good compromise between good mechanical and tribological properties. Finally, a mapping of the mechanical and tribological properties of the nc-TiC/a-C system is presented for the synthesis conditions employedItem Wear reduction effect on ultra-high-molecular-weight polyethylene by application of hard coatings and ion implantation on cobalt chromium alloy, as measured in a knee wear simulation machine(2001-07) Onate, J.I.; Comin, M.; Braceras, I.; García-Luis, A.; Viviente, J.L.; Brizuela, Marta; Garagorri, N.; Peris, J.L.; Alava, J.I.; Oate, J. I.; Garcia, A.; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIES; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe most important factor affecting performance and longevity of hip joint and knee implants is the wear rate of the ultra-high-molecular-weight polyethylene (UHMWPE) component. UHMWPE wear debris has been linked to complications including tissue inflammation, bone loss (osteolysis) and implant loosening. Reduction of debris has been addressed by investigating new polyethylene formulations, manufacturing and finishing processes, including surface treatments and coatings both on plastic and metallic components. There have been many studies on the effect of surface treatments and hard coatings on cobalt chromium and titanium alloys for prosthetic applications. However, most of them have used laboratory tribo-testers without much correlation to articulating movements in human joints. In this work, hard coatings (TiN and DLC) and surface treatments (nitrogen ion implantation) have been investigated as potential candidates to reduce wear of UHMWPE, when applied on the counter face cobalt chromium alloy. Also the effect of applying nitrogen ion implantation on the UHMWPE surface itself has been investigated. To evaluate wear performance a special knee wear simulator has been used with a combined rolling-sliding movement that corresponds to the most unfavourable situation in the knee. As testing materials, conventional coated and uncoated Co–Cr as well as Al2O3 femoral heads were used against UHMWPE plates to obtain comparative data. Testing was carried out at 50 MPa using distilled water at 37±2°C as a lubricant. Wear measurements on UHMWPE were made following ASTM F732 standard by weight loss measurements and also by laser profilometry. The results, up to 5 million wear cycles that represent approximately 3 years of implant life, clearly have demonstrated the beneficial effects of diamond-like carbon (DLC) and ion implantation (both on Co–Cr and UHMWPE) in reducing wear of UHMWPE. Similar values were also obtained for Al2O3 ceramic material. A wear reduction up to approximately five times was obtained by the former materials, in comparison with the uncoated control specimen. However, the ion plated TiN coating increased significantly wear on the UHMWPE. Transference of UHMWPE to the ball was very evident with the uncoated control and TiN coated Co–Cr, as observed by SEM, but with DLC and the ceramic material this occurred to a much lesser extent. Some micro-delamination at the worn surface of the UHMWPE was observed when wearing against uncoated Co–Cr, but was not clear in the rest options. Ion implantation and DLC can thus be two good candidate treatments to reduce wear of UHMWPE in cobalt chromium knee and hip joint implants in substitution of a more expensive ceramic material. This DLC has passed all biocompatible tests in accordance with FDA regulations and ISO 10993 standards for implantable devices. An example of a uniformly DLC coated femoral head and knee implant is shown.