Browsing by Author "Oñate, J. I."
Now showing 1 - 20 of 27
Results Per Page
Sort Options
Item Carbon layers formed on steel and Ti alloys after ion implantation of C+ at very high doses(1999) Viviente, J. L.; Garcia, A.; Loinaz, A.; Alonso, F.; 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 surface properties of steel and Ti 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 of carbon doses up to 8 × 1018 ions cm-2 has been performed on 440C martensitic stainless steel and Ti6A14V substrates under similar conditions and tribological and surface analysis results have been compared. Surface hardening occurred for all ion implantation conditions up to doses of 1018 ions cm-2 [1-3]. Higher doses resulted in a different behaviour for both materials. The stainless steel showed a softening while a twofold hardness increase was maintained in the Ti alloy. Nevertheless, at the higher implanted dose a decrease in hardness was also observed in the Ti alloy. Small area XPS analyses were performed to evaluate the chemical states after ion implantation and establish a relationship with the observed surface hardening. Depth profile XPS analyses showed that for a dose of 4 × 1018 ions cm-2 a carbon layer (with concentration over 85% at. C) was formed in the near surface region for both materials.Item Changes in tribological properties of an AISI 440C martensitic stainless steel after ion implantation of carbon at very high doses(1996-09) Alonso, F.; García, A.; Ugarte, J. J.; Viviente, J. L.; Oñate, J. I.; Baranda, P. S.; Cooper, C. V.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationIon implantation of N+ or C+ has been proven to be a suitable technique for improving tribological properties of steels. In the case of C+ implantation at very high doses, amorphization and a carbonaceous layer can be formed on the surface, the latter of which reduces adhesion when like-on-like material contact conditions occur, thereby decreasing surface wear and friction. A study to determine the influence of C+ ion implantation at very high doses (exceeding 1018 ions cm-2) on tribo-mechanical properties of AISI 440C steel is presented in this work. Ball-on-disc wear and friction tests using an AISI 440C steel ball showed a decrease of wear with increasing dose of more than one order of magnitude. A reduction in friction coefficient was also measured, from 1.0 down to 0.4. C 1s spectra from XPS analyses showed the presence of C-C bonds in the ion-implanted samples, suggesting the formation of a graphitic layer on the surface, responsible for the decrease in surface wear and friction after ion implantation.Item Characterization of Ti-6Al-4V modified by nitrogen plasma immersion ion implantation(1997-09) Alonso, F.; Rinner, M.; Loinaz, A.; Oñate, J. I.; Ensinger, W.; Rauschenbach, B.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationT1-6Al-4V alloy is commonly used in biomedical or aerospace applications, due to its excellent combination of chemical and mechanical properties, such as bioinertness, corrosion resistance or high strength to weight ratio. The use of surface treatments or coatings has widened the application possibilities of this alloy. The often observed poor tribological performance can be overcome by the correct choice of surface engineering methods. Ion implantation is a candidate among the different available processes and excellent results have been obtained in biomedical applications. However, when complex geometries are involved, it can be a difficult and less economically effective treatment. Plasma immersion ion implantation (PIII) offers the possibility of performing three-dimensional ion beam treatments, reducing the need for manipulation under vacuum to obtain a uniform treatment of geometrically complex parts. In this work, PIII was used to implant nitrogen in the Ti-6Al-4V alloy. The nitrogen plasma was generated with a 2.45 GHz microwave excitation, and a pulsed bias voltage of 45 kV with pulse repetition rates of 50 and 400 Hz were applied. Nitrogen retained doses were evaluated by means of Rutherford backscattering spectroscopy (RBS). Pin-on-disc wear and friction tests were performed on the implanted samples. An ultra high molecular weight polyethylene pin was used as the counterface material to partially simulate the conditions encountered in biomedical applications. A reasonable improvement in load bearing capacity with respect to the unimplanted alloy was observed after these tribological tests. However, no hardening could be measured after ion implantation. The worn surfaces were observed by scanning electron microscopy and optical profilometry after the tests and the type of wear mechanism was studied. The effect of the implantation was to increase the load at which breakthrough occurred on the protective surface layer.Item Current status of commercial ion implantation in Spain(1998-05) Oñate, J. I.; Alonso, F.; Braceras, I.; Sanz, A. L.; Rodríguez, R. J.; Tecnalia Research & Innovation; Centros PRE-FUSION TECNALIA - (FORMER); INGENIERÍA DE SUPERFICIESCommercial ion beam implantation has been steadily growing in Spain for the last 8 years. The emphasis has been placed, similar to other European countries, on the surface treatment of precision tooling and moulds rather than in large numbers of engineering components. This has somehow limited the growth of the market since ion implantation has to compete strongly with well established surface engineering alternatives, such as PVD, thermochemical and chemical processes. However, the possibilities of performing selected area ion implantation treatments at controlled temperatures and with computer control of the processing beam allows rapid treatment of selective areas at a very competitive level. One of the application areas where the process has been applied more successfully is in the area of transformation of plastics (injection and extrusion processes), where treatment of nozzles, mould cavities, calibrating extrusion dies, etc. is carried out on a regular basis. Also, ion implantation has yielded good results in the improvement of coining dies for the Spanish mint and is also currently applied for cutting tools for plastics, rubber and paper, as well as in tooling for the manufacturing of cans. Biomedical applications are still in the development and evaluation stage, largely due to the nature of the Spanish market, which has a less significant presence of native capital manufacturing companies. In this paper, an overview is presented of some of the current applications from the two active organisations in ion implantation, INASMET and AIN, with an indication of the areas in which actual research and technology development (R + TD) and industrial treatment services are performed.Item Deposition of hydrogenated B-C thin films and their mechanical and chemical characterization(1991-12-10) Oñate, J. I.; García, A.; Bellido, V.; Viviente, J. L.; Tecnalia Research & Innovation; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSConsiderable interest has arisen during the last decade on the deposition of diamond and diamond-like films because of their unique properties which suggest a range of applications. This paper reports on the r.f. plasma chemical vapour deposition of hydrogenated B-C films and evaluation of their mechanical and chemical properties. Thin films were deposited using various ratios of 5 vol.% B2H6 in H2 and CH4, while varying the substrate temperature, total gas pressure and r.f. power. It is shown that high B2H6-to-CH4 ratios can lead to deposition of very hard thin films. An ultramicrohardness technique, measuring hardness under loading, has been used within a load range 0.4-25.6 mN, in order to limit the penetration of the indenter. This testing approach shows hardness values of approximately three times that of a hardened and tempered AISI M2 high speed steel substrate. The films also exhibit an elastic behaviour, compared with the more plastic behaviour of the substrate material. Scratch adhesion testing shows maximum values for a critical load of approximately 20 N for 0.2 μm films on steel substrates. Thicker films exhibit lower adhesion values owing to the high stresses of the films. Adhesion of films deposited on Al2O3 substrates is higher and flaking is significantly reduced at high loads. IR spectra show that these films have significant B-C, B-H and C-H bonds. XPS data also demonstrate that carbidic bonds are present in C 1s and B 1s spectra; this jointly with the high stresses of films can explain the hardness values obtained.Item Effects of implantation treatments on micromechanical properties of M2 steel(1993-06-03) Alonso, F.; Viviente, J. L.; Oñate, J. I.; Torp, B.; Nielsen, B. R.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationThis work reports on the use of a depth-sensing technique at loads below 25.6 mN to evaluate properties of implanted M2 steel. Implantations were carried out on polished discs with N+, Cr+ +N+ and Cr+ ions at energies from 25 to 180 keV and total doses above 1017 ions/cm2. Single and multiple energy implants were carried out to evaluate the effect on mechanical properties of M2 steel by implantation with interstitial and substitutional elements. Nitrogen implantation showed improvements on surface hardness up to about 50% and higher elastic recovery than the substrate material. This can confirm the wear resistance results already obtained on tool steels used in cold forming and the processing of reinforced plastics. Combination of nitrogen and chromium ions presented similar hardening effects even at greater depths, while implantation of chromium showed only a very marginal improvement in hardness, with limited effect on elastic recovery values. XPS data are also presented to show the chemical effects of the implanted element related to the benefit in properties obtained.Item Effects of ion implantation on Ti-6Al-4V on its frictional behaviour against UHMWPE(1996-09) Alonso, F.; Ugarte, J. J.; Sansom, D.; Viviente, J. L.; Oñate, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS; Tecnalia Research & InnovationThe aim of this work was to study the effect of carbon ion implantation and a DLC coating on the friction response of T1-6Al-4V/UHMWPE materials used for biomedical implants, and on the endurance of the protective oxide layer of the Ti alloy at increasing loads. Carbon implantation was carried out at doses ranging from 2 × 1017 to 10 × 1017 ions cm-2 and energies from 75 to 180 keV. This implantation procedure produced a more than twofold improvement in hardness, as evaluated by a dynamic micro-indentation technique at increasing loads from 0.4 to 10 mN. Dry pin-on-disc tribological tests, using an UHMWPE pin, showed that some of the implantation treatments effectively protected the surface of the Ti alloy, without producing a break in the protective passive oxide layer and exhibited low friction values, similar to those obtained in DLC coatings. No direct correlation has been found, however, between the hardening induced by ion implantation and the improved tribological response. Formation of TiC precipitates could account for the hardening effect observed after carbon implantation and, in addition, implantation may cause stabilisation of the protective oxide layer on the titanium surface.Item Effects of plasma immersion ion implantation of oxygen on mechanical properties and microstructure of Ti6A14V(1998-05) Loinaz, A.; Rinner, M.; Alonso, F.; Oñate, J. I.; Ensinger, W.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationPlasma immersion ion implantation (PIII) is a surface treatment with increasing interest, as it offers the possibility of performing three-dimensional ion beam treatments, reducing the need for manipulation under vacuum to obtain a uniform treatment in geometrically complex parts. In this work the PIII process has been used to perform surface treatment on Ti6A14V alloy. This Ti alloy is commonly used in aerospace and biomedical applications, due to its good combination of mechanical and chemical properties, such as strength to weight ratio, corrosion resistance or bioinertness. However, due to its poor tribological properties, the use of surface treatments to improve wear resistance or decrease friction coefficient is often recommended. PIII has been used to implant the surface of Ti6A14V alloy with oxygen ions. The oxygen plasma was generated by electron cyclotron resonance microwave excitation, working at two different pressures. At the lower pressure plasma density was increased by means of an external ring magnet. High voltage pulses of -40 kV, at of 400 and 600 Hz pulse repetition rates, were applied. Elastic recoil detection (ERD) analysis showed retained doses in the range of 3 × 1017 to 1 × 1018 O atoms cm-2, with oxygen concentration values ca 65% in the near surface region. Surface mechanical properties such as hardness, wear and friction have been evaluated. Microindentation tests showed an increase of up to 100% in the surface hardness of the ion implanted samples compared to the non implanted material. Dry pin-on-disk tests with spherical ended UHMWPE pins showed a very significant increase in wear resistance in oxygen implanted Ti6A14V samples. Scanning electron microscopy and optical profilometry showed an important roughening of the Ti alloy surface after PIII treatment under selected conditions.Item Evaluacion del comportamiento de materiales para protesis de rodilla en simulador de desgaste(1999-12) Comín, M.; Peris, J. L.; Oñate, J. I.; Atienza, C.; Mollá, F.; Prat, J.; Tecnalia Research & InnovationThe wear of materials used to manufacture knee prostheses, one of the main problems of these implants, was evaluated with a simulator. The simulator applied to samples loads and displacements similar to those borne by the prosthesis after implantation. The material pair CrCoMo vs high- molecular-weight polyethylene, the most widely used in the manufacture of this type of prostheses, was used as a reference to test in the simulator of an ionic implantation over both components, and coverings of titanium nitride and carbon on the metal component. Polyethylene wear was measured using gravimetric methods and laser perfilometry. The results showed that the titanium nitride covering was less resistant, while the ionic implantation and covering with titanium nitride and carbon reduced polyethylene wear compared with the reference materials of CrCoMo vs polyethylene.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 Improved tribological behaviour of MoS2 thin solid films alloyed with WC(2001) Oñate, J. I.; Brizuela, M.; Garcia-Luis, A.; Braceras, I.; Viviente, J. L.; Gomez-Elvira, J.; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIES; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSMoS2 is a broadly accepted solid lubricant for space mechanisms. However, the tribological properties can be affected by the deposition parameters that can in turn influence structure and composition of the films. One important drawback of MoS2 is its sensitivity to atmospheric water vapour which renders the film unsuitable for use under high humidity levels and forces the taking of precautions during ground qualification testing and storage of solid lubricated space mechanisms. Recently, and with developments made in magnetron sputtering PVD technology an interest has arisen in the production of more wear and moisture resistant MoS2 films. This has been evaluated by alloying the film by co-depositing a range of metallic and non-metallic elements. This paper follows a previous report in which Ti metal was co-deposited with MoS2 and a low friction under vacuum and atmospheric conditions was demonstrated. However, it was felt that extended durability was still needed for the benefit of space community. In this work, preliminary results on the deposition of WC-MoSx films by magnetron sputtering are presented. Vacuum tribology of these films, at 0.75 and 0.95 GPa contact stresses, shows that the friction coefficients are similar to those obtained in conventional MoS2 films, but there is a significant improvement in durability. When evaluating the performance of these films under atmospheric conditions and at various humidity levels (from 40 to 60 % RH), the tribological response has also been very good, with average friction coefficients as low as 0.07 and a durability as high as 450.000 wear cycles. XPS analyses have shown that the films consist mainly of a MoSx lubricating matrix in which a carbidic wear resistant WC phase is embedded. This combination ensures a low friction behaviour while providing a higher resistance to wear.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 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 Microindentation and tribological study of nitrogen implanted martensitic steels(1992-01) Oñate, J. I.; Alonso, F.; Dennis, J. K.; Hamilton, S.; Tecnalia Research & Innovation; Centros PRE-FUSION TECNALIA - (FORMER)Ion implantation is an established technique for the modification of the surface characteristics of materials by bombardment with high energy ions to improve properties such as wear resistance, hardness, fatigue, and friction behaviour. The low treatment temperatures involved in this technique ensure the avoidance of distortion and are ideal for components and tools finished to a high precision. Results obtained in the present work illustrate that wear resistance and surface hardness of AISI M2, D2, and 420 steels can be improved by nitrogen implantation at doses >1017 ions C-2. Lubricated Falex wear tests carried out using high loads showed an enhancement in wear resistance and a significant decrease in the coefficient of friction, especially for 420 and D2 steels. Use of an ultramicrohardness technique has shown that the true hardness of implanted surface layers is greater than the values obtained by conventional microhardness methods that result in penetration below the implanted depth. Other mechanical property data, such as elastic recovery and elastic modulus, can also be obtained from the shallow implanted layer. The results indicate that implantation of nitrogen can bring about a significant change of the near surface region of steels, promoting a change in the dominant wear mechanism and thus improving tribological behaviour of the surface.Item A study of dual chromium plus carbon ion implantation into high speed steel(1994) Oñate, J. I.; Alonso, F.; Viviente, J. L.; Arizaga, A.; Tecnalia Research & Innovation; Centros PRE-FUSION TECNALIA - (FORMER); TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSA large volume of data is now available on the implantation of nitrogen ions into a wide range of steels and other materials such as titanium alloys. In some cases, especially when the substrate steel materials consist of hard martensitic structures, the benefits of nitrogen implantation are less significant. A combination of titanium plus carbon ions has often been reported to produce a significant improvement in the tribological properties of bearing and high speed steels. This work reports on dual ion implantation of chromium plus carbon ions into an AISI M3:2 high speed steel, comparing the results with a titanium plus carbon implantation procedure. Implantations were carried out in a high current Danfysik ion implanter on surface ground and polished discs at doses above 1017 ions cm-2 and energies ranging from 40 to about 180 keV to yield selected concentration profiles. Ultramicrohardness tests using a dynamic microprobe, and friction and wear testing, were carried out to evaluate the mechanical properties produced by the treatment. It is shown that this implantation procedure can yield a hardening of up to a factor of 1.2 for the highest carbon dose; this effect is very similar to that observed on multiple energy nitrogen implantation to a combined dose of up to 5.5 × 1017 ions cm-2. The results of friction testing also indicate that a relatively significant reduction from about 0.65 to 0.5 is observed in the coefficient of friction under the conditions investigated. X-ray photoelectron spectroscopy analyses indicated that the chromium and carbon implanted elements can combine forming carbidic bonds, and when the carbon dose is increased the underlying C 1s spectra show carbidic and graphitic bonds.Item Submicron characterization of B-C:H thin films produced by RF plasma CVD(1992-03-25) García, A.; Bellido, V.; Flaño, N.; Oñate, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationDiscrepancies might arise among different laboratories when evaluating hardness values of thin coatings with conventional microhardness testers, which rely on optical examination of the indentation. These procedures can lead to significant measurement errors and misleading results if applied loads are either low, producing very small indentations that are difficult to measure, or relatively high so that penetration can be beyond coating and into the base material. This paper reports on the application of a microindentation technique to sample hardness and elastic properties of thin B-C:H films within ca. 10% of the total thickness of the coating in order to minimize the influence of the base material and to avoid optical measurement restrictions. Coatings were produced by RF plasma CVD from 5% B2H6 in H2 and CH4 gas mixtures. Deposition parameters, mainly gas composition, RF power and total pressure were modified to obtain coatings of different C/B composition ratios and mechanical properties. Ultra-microhardness measurements were carried out dynamically under loads from 0.4 to a maximum of 25.6 mN and the indentation depth was continuously monitored as a function of applied load. Coatings with the lowest C/B% atomic ratios showed the most significant increment in hardness of about three times that of the hardened and tempered AISI M2 high speed steel base material. The coatings also presented a high elastic recovery after the indentation test, and the "hardness/(elastic modulus)2" parameter indicates that the coating can provide significant protection under mild abrasive wear mechanisms. Wear tests showed an improvement in friction coefficient compared to M2 steel and TiN coating, but the wear performance of the coatings can be impaired by a lack of adhesion to the M2 steel substrate.Item Tribolab: An experiment on space tribology. In-orbit data at the ISS(2009) Brizuela, M.; García-Luis, A.; Oñate, J. I.; Garmendia, I.; INGENIERÍA DE SUPERFICIES; TECNOLOGÍAS DE HIDRÓGENO; Tecnalia Research & InnovationIn February 2008, the Discovery Shuttle mission ST-122 brought the European Columbus Space Laboratory to the International Space Station (ISS). One of the Columbus External Payload Facilities (CEPA) is occupied by the European Technological Exposure Facility (EuTEF), a group of seven different scientific experiments, where the tribology experiment Tribolab is located. The TriboLAB instrument is a space tribometer which performs tests with different lubricants and different devices at basic and component level respectively: pin-on-disk and ball bearing. TriboLAB allows to investigate the tribological behavior of lubricants under conditions not possible to simulate simultaneously on earth: g-0, vacuum, microvibrations, LEO radiation, etc. It is interesting to point out that previously obtained tribological data on Earth (friction coefficients, friction torques and long term durability of the lubricant thin layers) are going to be compared to the results obtained in the microgravity conditions of the LEO orbit of the ISS. In this way, a correlation between both data series is going to be done and the effect of the severe conditions that the lubricant has to withstand on the space is going to be evaluated. Up to now, these data are not available and the mechanisms designers will benefit from the knowledge obtained in this experiment for their future designs, as lubricants play a key role in the deployment of mechanisms and structures. Previous works by the authors have shown that the WC alloyed MoSx coating shows better tribological properties than conventional MoS2 coating, both under vacuum and under air at higher humidity conditions [1,2]. This work reports on the results of the pin-on-disk tests on the alloyed MoSx coatings in orbit in comparison with the results obtained under laboratory conditions on ground. These tests have shown that the solid lubricating film maintain very low friction levels of 0.04 and reach a maximum of 1,011,000 wear cycles demonstrating a similar behavior to that experienced on ground.Item Tribología de nuevas capas autolubricantes producidas mediante PVD(2005) Oñate, J. I.; Brizuela, M.; Garcĩa-Luis, A.; Braceras, I.; Pacheco, S.; Viviente, J. L.; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIES; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSLas capas de MoS2 depositadas mediante PVD tienen baja fricción en vacío pero se degradan con facilidad al aire, especialmente en presencia de humedad. Este trabajo describe el desarrollo de nuevas capas de MoS^ modificadas con WC. En ensayos de "bola sobre disco" a 0,75 GPa, las capas presentaron una fricción muy baja y estable (< 0,04) en vacío. Se obtuvo una durabilidad superior a 1 millón de ciclos, mostrando un desgaste de 1,3 X 10e-16 me3 /Nm, mejorado respecto a otras capas de MoS2. El coeficiente de fricción aumentó a 0,15 y la durabilidad disminuyó hasta 1 a 3 x 10e5 ciclos en aire hasta 70 % HR.El análisis superficial mostró ratios de S/Mo superiores a 1,2, con menos del 2 % de oxígeno, demostrando carácter lubricante.Item Tribological effects of yttrium and nitrogen ion implantation on a precipitation hardening stainless steel(1994-08) Alonso, F.; Arizaga, A.; Garcia, A.; Oñate, J. I.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationYttrium, nitrogen and combined yttrium and nitrogen implantations have been carried out on an ASTM A286 precipitation hardening iron base alloy to evaluate the benefits in their tribological behaviour. Microindentation tests have shown a significant 20%-60% increment in hardness on the nitrogen implanted material, with a limited improvement in elastic recovery of the indentation. An abrasive test on the same material has also produced a 50% reduction in scratch depth. Y+ and Y+ + N+ implantations also hardened the material but to a lesser extent. Reciprocating ball on disk friction and wear testing at 400 °C resulted in very severe damage in all cases. X-ray photoelectron spectroscopy analyses combined with Ar sputtering have disclosed that nitrogen is mainly in a nitrided form, yttrium remains oxidized at the surface, below which there is an apparent increase in the metallic bond.