Browsing by Keyword "Ion implantation"
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Item Bacterial adhesion reduction on a biocompatible Si+ ion implanted austenitic stainless steel(2011-10-10) Gallardo-Moreno, A. M.; Multigner, M.; Calzado-Martín, A.; Méndez-Vilas, A.; Saldaña, L.; Galván, J. C.; Pacha-Olivenza, M. A.; Perera-Núñez, J.; González-Carrasco, J. L.; Braceras, I.; Vilaboa, N.; González-Martín, M. L.; INGENIERÍA DE SUPERFICIESThe colonization of an implant surface by bacteria is an extremely important medical problem, which often leads to the failure of medical devices. Modern surface modification techniques, such as ion implantation, can confer to the surfaces very different properties from those of the bulk underlying material. In this work, austenitic stainless steel 316 LVM has been superficially modified by Si+ ion implantation. The effect of surface modification on the biocompatibility and bacterial adhesion to 316 LVM stainless steel has been investigated. To this aim, human mesenchymal stem cells (hMSCs), as precursor of osteoblastic cells, and bacterial strains relevant in infections related to orthopedic implants, i.e., Staphylococcus aureus and Staphylococcus epidermidis, have been assayed. For the understanding of changes in the biological response associated to ion implantation, variations in the chemical surface composition, topography, surface Gibbs energy, isoelectric point and in vitro corrosion behavior have been evaluated. hMSCs adhesion, viability and differentiation to the osteoblastic lineage were unaffected by Si+ ion implantation. On the other hand, Si+ ion implantation diminished the number of attached bacteria in static conditions and led to smaller adhesion rates and retention strength. The ability of implanted surfaces to reduce the bacterial adhesion was higher for Staphylococcus epidermidis than for Staphylococcus aureus. This study proposes Si+ ion implantation as an effective way of reducing bacterial adhesion on 316 LVM stainless steel surfaces without compromising its good biocompatibility.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 Decrease of Staphylococcal adhesion on surgical stainless steel after Si ion implantation(2014-08-15) Braceras, Iñigo; Pacha-Olivenza, Miguel A.; Calzado-Martín, Alicia; Multigner, Marta; Vera, Carolina; Broncano, Luis Labajos; Gallardo-Moreno, Amparo M.; González-Carrasco, José Luis; Vilaboa, Nuria; González-Martín, M. Luisa; INGENIERÍA DE SUPERFICIES; Biomateriales316LVM austenitic stainless steel is often the material of choice on temporal musculoskeletal implants and surgical tools as it combines good mechanical properties and acceptable corrosion resistance to the physiologic media, being additionally relatively inexpensive. This study has aimed at improving the resistance to bacterial colonization of this surgical stainless steel, without compromising its biocompatibility and resistance. To achieve this aim, the effect of Si ion implantation on 316LVM has been studied. First, the effect of the ion implantation parameters (50 keV; fluence: 2.5-5 × 10 16 ions/cm 2 ; angle of incidence: 45-90°) has been assessed in terms of depth profiling of chemical composition by XPS and nano-topography evaluation by AFM. The in vitro biocompatibility of the alloy has been evaluated with human mesenchymal stem cells. Finally, bacterial adhesion of Staphylococcus epidermidis and Staphylococcus aureus on these surfaces has been assessed. Reduction of bacterial adhesion on Si implanted 316LVM is dependent on the implantation conditions as well as the features of the bacterial strains, offering a promising implantable biomaterial in terms of biocompatibility, mechanical properties and resistance to bacterial colonization. The effects of surface composition and nano-topography on bacterial adhesion, directly related to ion implantation conditions, are 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 Growth of carbon layers on Ti-6Al-4V alloy by very high dose carbon implantation(1997-12) García, A.; Viviente, J. L.; Alonso, F.; Loinaz, A.; Oñate, J. I.; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationIon implantation is a useful technique to tailor the surface properties of Ti-6Al-4V alloys. In particular, very high dose C+ implantation (in the range of 1018 ions cm-2) offers the possibility of forming carbon layers without a sharp interface with the substrate material. In this study, ion implantation treatments have been performed on Ti-6Al-4V with C+ doses up to 4 × 1018 ions cm-2. XPS analyses have been carried out to evaluate the chemical states after ion implantation. A change in C 1s binding energies has been observed depending on the carbon concentration in the implanted layer. At relatively low or medium concentrations (about 41 at.% C) mainly carbidic bonds were present, but when the concentration increased up to 88 at.%, the binding peak shifted to values that correspond to C-C bonds. Dynamic microindentation techniques, used to evaluate the hardness of the implanted material, have shown a significant change in relative hardness as a function of C+ dose, owing to the formation of a carbon layer in the titanium alloy surface. A two-fold increase in the hardness ratio and elastic recovery values is observed for the highest implanted dose.Item Histomorphometric study of ion implantation and diamond-like carbon as dental implant surface treatments in beagle dogs(2007-03) De Maeztu, Miguel A.; Braceras, Iñigo; Alava, J. Iñaki; Sánchez-Garcés, M. Angeles; Gay-Escoda, Cosme; INGENIERÍA DE SUPERFICIESPurpose: Improvements in the bone-implant interface can provide clinical benefits, such as increasing the amount of bone in contact with the implant and shortening the time required to achieve sufficient bone appositioning to allow early prosthetic loading. The present study describes the results obtained with 2 new surface treatments: (a) CO ion implantation; and (b) diamond-like carbon (DLC) coating. Materials and Methods: Each group (ion implantation, DLC, and the control group, turned titanium) consisted of 12 samples. Beagle dogs subjected to previous partial edentulation were used. Dual histologic evaluation was made of percentage bone-implant contact (% BIC) of all samples based on conventional histomorphometric analysis and environmental scanning electron microscopy (ESEM). Results: The results obtained after 3 and 6 months of dental implant placement showed greater and faster bone integration in the CO ion implantation group (61% and 62% BIC, respectively) compared with the DLC group (47% and 50%); the data corresponding to the ion implanted samples were statistically significant compared with the control group (33% and 49% BIC after 3 and 6 months, respectively). Conclusions: The results showed improved % BIC for implants with ion-implanted surfaces in comparison to DLC coating and machined controls. Furthermore, bone integration appeared to be accelerated in the ion implantation group, since high % BIC values were recorded in the early stages after in vivo implantation.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 Improvement of osseointegration of titanium dental implant surfaces modified with CO ions: a comparative histomorphometric study in beagle dogs(2008-05) De Maeztu, M. A.; Braceras, I.; Alava, J. I.; Gay-Escoda, C.; INGENIERÍA DE SUPERFICIESThe aim of this study was to compare carbon-oxygen (CO) ion implantation as a surface treatment with diamond-like carbon and commercially treated implants, including double acid-etched (Osseotite®), oxidized (TiUnite®) and sandblasted and acid-etched (SLA®), using machine-turned titanium implants as control. A total of 72 dental implants divided into 6 groups were placed in the mandibles of 12 beagle dogs. Evaluation was performed by conventional light transmission microscopy and environmental scanning electron microscopy (ESEM). The histological results obtained via ESEM demonstrated bone-implant contact percentage (%BIC) for implants treated with CO ion implantation of 61% and 62% at 3 and 6 months, respectively. At the same time points, the values were 48% and 45% for double acid-etched, 46% and 52% for sandblasted and acid-etched, 55% and 46% for oxidized, and 33% and 49% for machine-turned titanium control implants. Values of %BIC were statistically significantly higher in implants treated with CO ion implantation compared to the commercially treated implant group (p = 0.002 and p = 0.025) and the control implants (p = 0.001 and p = 0.032) at 3 and 6 months, respectively. No significant differences were observed between the three groups of commercially treated implants. The larger %BIC of the ion-implanted group was observable at an early stage.Item Improvement of tribological properties by ion implantation(1998-04-01) Oñate, J. I.; Alonso, F.; García, A.; Tecnalia Research & Innovation; Centros PRE-FUSION TECNALIA - (FORMER)Ion implantation is a surface technology process that is emerging as a viable and economical technique for the improvement of tribological properties of engineering components. This treatment is highly versatile for modifying surface properties of materials by a careful selection of ions to be implanted and processing conditions. The study of tribological properties induced by ion implantation has received increasing attention during the last years and a large volume of literature exists on this subject. Most of these reports deal with the effect of selected implantation treatments on steels and other materials of engineering importance, such as titanium and aluminium alloys. This work indicates some of the mechanisms that have been postulated as to account for the beneficial effects of ion implantation on the friction and wear of these materials. The paper also discusses how the modification of surface micro structure and mechanical and chemical properties can significantly influence the tribological performance of engineering materials. The extent of this influence depends on the type of wear and friction mechanisms that are operative in the tribosystem. Some examples are presented on the effect of ion implantation on tribo-mechanical properties of selected materials, including steels, hard chromium coatings and titanium alloys. Under certain operative conditions, ion implantation can lower the adhesion between surfaces and promote a change in operative wear mechanisms during run-in. Results show how ion implantation of carbon at very high doses can lead to the formation of a solid lubricant layer on steels and titanium alloys. C 1s spectra obtained from XPS analyses on these surfaces indicate the presence of graphitic bonds at the near surface with a contribution of carbidic bonds beneath the surface.Item In vitro corrosion behaviour of surgical 316LVM stainless steel modified by Si+ ion implantation – An electrochemical impedance spectroscopy study(2016-08-15) Galván, J.C.; Larrea, M.T.; Braceras, I.; Multigner, M.; González-Carrasco, J.L.; INGENIERÍA DE SUPERFICIESThis work deals with the surface modification of 316LVM stainless steel by Si+ ion implantation and the in vitro study of its effect on the short-term corrosion behaviour and ion release. In order to achieve a high Si content close to the surface, the experimental set up was designed with different implantation doses, acceleration voltages and angles of incidence. Corrosion tests were carried out by Electrochemical Impedance Spectroscopy (EIS). A special feature of this paper is the evaluation of the EIS data obtained through a critical analysis of the existing equivalent electrical circuits, in order to establish adequate parameters and scientific criteria to propose a classification of the corrosion response of the investigated surfaces. It has been demonstrated that doses of Si+ ion implantation equal to 2.5 × 1016 ion/cm2 and an acceleration voltages of 50 keV enhanced the corrosion protection. In contrast, higher ion-implantation dose (1 × 1017 ion/cm2) and acceleration voltage (80 keV) produced worse results, probably due to the development of strain induced α’-martensite. The quantity of relevant ions (Cr, Fe, Mn, Mo, Ni and Si) released to the medium was determined by an optimized Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) method. It has been shown that a better corrosion resistance is accompanied by a reduction in the amount of ions released.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 Ion implantation induced nanotopography on titanium and bone cell adhesion(2014-08-15) Braceras, Iñigo; Vera, Carolina; Ayerdi-Izquierdo, Ana; Muñoz, Roberto; Lorenzo, Jaione; Alvarez, Noelia; De Maeztu, Miguel Ángel; INGENIERÍA DE SUPERFICIES; BiomaterialesPermanent endo-osseous implants require a fast, reliable and consistent osseointegration, i.e. intimate bonding between bone and implant, so biomechanical loads can be safely transferred. Among the parameters that affect this process, it is widely admitted that implant surface topography, surface energy and composition play an important role. Most surface treatments to improve osseointegration focus on micro-scale features, as few can effectively control the effects of the treatment at nanoscale. On the other hand, ion implantation allows controlling such nanofeatures. This study has investigated the nanotopography of titanium, as induced by different ion implantation surface treatments, its similarity with human bone tissue structure and its effect on human bone cell adhesion, as a first step in the process of osseointegration. The effect of ion implantation treatment parameters such as energy (40-80 keV), fluence (1-2 e17 ion/cm 2 ) and ion species (Kr, Ar, Ne and Xe) on the nanotopography of medical grade titanium has been measured and assessed by AFM and contact angle. Then, in vitro tests have been performed to assess the effect of these nanotopographies on osteoblast adhesion. The results have shown that the nanostructure of bone and the studied ion implanted surfaces, without surface chemistry modification, are in the same range and that such modifications, in certain conditions, do have a statistically significant effect on bone tissue forming cell adhesion.Item Ion implantation of TiN films with carbon or nitrogen for improved tribomechanical properties(1996-10) Sansom, D.; Viviente, J. L.; Alonso, F.; Ugarte, J. J.; Oñate, J. I.; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationIn the field of engineering materials, the study of titanium nitride (TiN) films has attracted great interest because of its unique combination of properties. This paper is concerned with the implantation of nitrogen or carbon ions into TiN films to evaluate and obtain the optimum conditions for increased tribological resistance. A commercially available titanium nitride coating produced by ion plating, of approximately 3.5 μm thickness, was treated by implantation of nitrogen or carbon ions at energies of 100 and 75 keV, respectively. The dose range was between 5 × 1016 and 1 × 1018 ions cm-2. It has been observed that a suitable implantation procedure can lead to a maximum hardness improvement of about 15%, as evaluated with a dynamic micro-indentation method at loads from 0.4 to 10 mN. Wear tests performed on an unlubricated reciprocating apparatus, using an alumina ball with a load of 9.8 N and at a speed of 150 cycles min-1, showed that implantation of nitrogen and carbon can reduce wear by 22% and 42%, respectively. Small-area X-ray photoelectron spectroscopy (SAXPS) was used to evaluate the concentration of implanted elements as a function of depth. The analysis showed that in the high-dose C+-implanted sample a very high percentage of the carbon remained as pure carbon, whereas in the lower-dose C+-implanted sample the carbon stayed mainly in a carbidic form. In the case of nitrogen implantation, no large variations in the state or concentrations were recorded.Item Mechanical properties and structure of Ti-6A1-4V alloy implanted with different light ions(1995-10) Alonso, F.; Arizaga, A.; Quainton, S.; Ugarte, J. J.; Viviente, J. L.; Oñate, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationThe effect of N+ and C- implantation on the properties of Ti-6Al-4V alloy is widely documented. However, some authors claim that other light ions, such as O+ or B+, also have an effect on this alloy, improving its mechanical properties. In this work, Ti-6Al-4V alloy samples have been implanted with C+, N+ and O+ light ions. Energies from 50 to 180 keV and doses of the order of 1017 ion cm-2 have been used, keeping the substrate temperature below 500°C. Mechanical properties such as the hardness or elastic recovery have been evaluated by means of microindentation tests, with a loading-unloading cycle at loads up to 10 mN. An increase in surface hardness of more than 100% has been observed in most of the implanted samples. Pin-on-disc wear tests under lubricated conditions have been performed to evaluate and compare the tribological behaviour of implanted samples against ultrahigh molecular weight polyethylene. A decrease in the friction coefficient from 0.1 to 0.05, resulting from ion implantation, has been observed. Unlubricated wear tests using an alumina ball on a Ti-6Al-4V disc have also been carried out. Wear tracks on the Ti-6Al-4V, evaluated by means of optical profilometry and scanning electron microscopy, have shown that implantation can improve the abrasive wear resistance by two orders of magnitude. X-ray photoelectron spectroscopy analyses also were carried out on selected samples, showing the presence of hard phases, such as oxides or carbides, in the implanted samples.Item Risk analysis and implants(2008-11) Braceras, I.; Ipiñazar, E.; De Maeztu, M. A.; Alava, J. I.; INGENIERÍA DE SUPERFICIES; VALORIZACIÓN DE RESIDUOSAccording to the Medical Devices Directive, both the preparation for clinical trials and marketing of implants require that a risk analysis is performed. This paper presents a risk analysis for a dental implant in the framework of the risk management process carried out for the preparation of a multi-centre clinical trial, where likely hazards, failure modes and their severities, probabilities and detectabilities are assessed, together with a review of the related scientific literature. The clinical study aimed to evaluate a new ion implantation-based implant surface designed for the promotion of more extensive and faster osseointegration.Item The use of preliminary ion implantation and heating on the substrate for modifying TiN coating properties and TiN/substrate interface(2001-07) Solodukhin, I. A.; Khodasevich, V. V.; Uglov, V. V.; Brizuela, M.; Oate, J. I.; INGENIERÍA DE SUPERFICIES; Tecnalia Research & InnovationThe influence of preliminary implantation of argon ions on a carbon steel substrate and deposition temperature on the texture and adhesion of TiN coatings deposited by cathodic arc plasma deposition has been investigated. The samples have been evaluated by glancing X-ray diffraction, Auger-electron spectroscopy and scratch adhesion testing. Strengthening of the (220) TiN texture with increasing ion implantation dose on the substrate has been revealed. An increment of deposition temperature (from 450 up to 720 K) leads to a more chaotic orientation of TiN crystallites. An increase of transitional layer thickness (by 60% for the Ti profile) is only observed when depositing the coating at high temperature (720 K). However, both the preliminary implantation process and the heating of the substrate lead to an adhesion improvement of TiN coatings.Item X-ray photoelectron spectroscopy characterization of high dose carbon-implanted steel and titanium alloys(1999-04) Viviente, J. L.; García, A.; Alonso, F.; Braceras, I.; Oñate, J. I.; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Centros PRE-FUSION TECNALIA - (FORMER); INGENIERÍA DE SUPERFICIES; Tecnalia Research & InnovationA study has been made of the depth dependence of the atomic fraction and chemical bonding states of AISI 440C martensitic stainless steel and Ti-6Al-4V alloy implanted with 75 keV C + at very high doses (above 10 18 ions cm -2 ), by means of X-ray photoelectron spectroscopy combined with an Ar + sputtering. A Gaussian-like carbon distribution was observed on both materials at the lowest implanted dose. More trapezoidal carbon depth-profiles were found with increasing implanted doses, and a pure carbon layer was observed only on the titanium alloy implanted at the highest dose. The implanted carbon was combined with both base metal and carbon itself to form metallic carbides and graphitic carbon. Furthermore, carbon-enriched carbides were also found by curve fitting the C 1s spectra. The titanium alloy showed a higher carbidic contribution than the steel implanted at the same C + doses. A critical carbon concentrations of about 33 at.% and 23 at.% were measured for the formation of C-C bonds in Ti-6Al-4V and steel samples, respectively. The carbon atoms were bound with metal to form carbidic compounds until these critical concentrations were reached; when this C concentration was exceeded the proportion of C-C bonds increased and resulted in the growth of carbonaceous layers.