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Diamond-like carbon (DLC) coatings have been extensively studied over the last two decades in the field of materials engineering. The addition of effective bactericidal agents like silver suggests the potential application of silver-doped DLC coatings in the biomedical sector. In this paper, DLC coatings containing about 2 at. % Ag were grown on CoCrMo substrates by pulsed filtered cathodic arc co-deposition using pure graphite and silver targets. Morphology, structure and chemical composition of the coatings were characterized by SEM, XPS, XRD, Raman and HRTEM. Wettability and surface free energy were also measured. Mechanical properties were analyzed by means of nanoindentation and Rockwell-C adhesion tests. Corrosion resistance of coated and uncoated samples was determined by potentio-dynamic polarization tests in Hank's solution. Cytotoxicity and antibacterial activity against S. aureus and P. aeruginosa were also studied. For comparative purposes, nitrogen-doped DLC coatings obtained by RF magnetron sputtering were also prepared and characterized. Well-adhered and corrosion resistant Ag-DLC nanostructured coatings of up to 1.5 µm thick and 21 GPa in hardness were obtained. The doping concentration of silver studied in this work seems to be optimal for the preparation of non-cytotoxic coatings with a significant bactericidal activity. This work has been financed by the Ministry of the Economy, Industry and Competitiveness of Spain under the project BIOPLASMA (MAT2015-67103-C4).

In this study we have analysed the indentation hardness and modulus of cathodic arc deposited CrTiAlN coatings as a function of the stoichiometric variables Ti/Cr, Al content and cation mix. The coatings have been prepared using a combinatorial cathode composition approach, leading up to 14 different stoichiometries produced in 5 batches. The coatings have been inspected by glow discharge optical emission spectroscopy, scanning electron microscopy, X-ray diffraction and nanoindentation techniques. The coatings develop crystalline structures compatible with solid solutions of face-centered cubic unit cells for all the compositions produced. Such unit cells exhibited a downwards lattice parameter dependency on the aluminum concentration of the coatings (from 0.417 nm down to 0.413 nm). The indentation hardness as a function of the Ti/Cr is compatible with other previous studies reported. The films hardnesses and moduli also increase as the aluminum concentration increases (21 GPa up to 34 GPa). Both indentation responses upon Ti/Cr and Al are attributed to solid solution strengthening. However in order to prove this statement, the indentation hardness and modulus were studied as a function of the mixing term of the cations, as this term is well representative of the solid solution compositional map. The observed results unambiguously evidence that the solid solution strengthening effect is confirmed on the basis of the dependency between the indentation hardness and the so called degree of mixing. This work has been funded by the Spanish Ministry of Science and Innovation of Spain through the project PGC2018-096855-A-C44. The authors also acknowledge the Centro para el Desarrollo Tecnológico e Industrial (CDTI) for the support of the excellence program CERVERA through the project CER2019-1003.

Due to its resistant to thermal shock and strength at elevated temperature, Titanium-Zirconium-Molybdenum (TZM) alloy is used for hot-work tooling up to 1500 °C. The friction and wear behaviour of the TZM alloy reciprocating against Al 2 O 3 and Si 3 N 4 in different conditions were investigated. It has an adhesion and/or oxidation character with a high coefficient of friction when dry sliding against an alumina ceramic ball. It is characterised with reduced wear in an abrasion mode when reciprocally sliding against a Si 3 N 4 ceramic ball. In addition, the friction and wear between TZM and an Al 2 O 3 ball under unidirectional sliding conditions can be reduced when lubricating molybdenum oxides was formed at higher temperature i.e. 600 °C. Finally, the friction and wear mechanisms involved are discussed.

Maraging steels combine excellent mechanical properties at medium-high temperatures with good fracture toughness, but they usually require the aid of thermochemical treatments to enhance superficial properties such as resistance to abrasive wear and corrosion resistance. In particular, plasma nitriding, due to its duration and temperature, which are compatible with the age-hardening cycles of maraging steels, permits the realization of both processes simultaneously. In this work, simultaneous ageing and arc-activated plasma nitriding of maraging steel grade 300 were studied as a function of the working pressure of the gases (N2 and Ar) present in the vacuum reactor chamber. In addition, the influence of the operating pressure was established by analysing the capacity of the plasma to penetrate in 2.5 mm in diameter blind holes. In-depth chemical composition, hardness and micro-hardness profiles, X-Ray diffraction, roughness, tribological characterization and corrosion tests were carried out to compare maraging steel samples treated in one simultaneous plasma nitriding and ageing process and in two-step processes. Metallographic tests and nanoindentation measurements were performed to study how the plasma penetrates and diffuses into the blind holes and how the nitride case layer thickness formed at the inner surfaces of the holes changes as a function of the distance to the surface for various working pressures.

The application of surface treatments that incorporate silver or copper as antibacterial elements has become a common practice for a wide variety of medical devices and materials because of their effective activity against nosocomial infections. Ceramic tiles are choice materials for cladding the floors and walls of operation rooms and other hospital spaces. This study is focused on the deposition of biocide physical vapor deposition (PVD) coatings on glazed ceramic tiles. The objective was to provide antibacterial activity to the surfaces without worsening their mechanical properties. Silver and copper-doped chromium nitride (CrN) and titanium nitride (TiN) coatings were deposited on samples of tiles. A complete characterization was carried out in order to determine the composition and structure of the coatings, as well as their topographical and mechanical properties. The distribution of Ag and Cu within the coating was analyzed using glow discharge optical emission spectrometry (GD-OES) and field emission scanning electron microscope (FE-SEM). Roughness, microhardness, and scratch resistance were measured for all of the combinations of coatings and dopants, as well as their wettability. Finally, tests of antibacterial efficacy against Staphylococcus aureus and Escherichia coli were carried out, showing that all of the doped coatings had pronounced biocide activity. This research was funded by Departamento de Innovación, Empresa y Empleo from Gobierno de Navarra and Fondo Europeo de Desarrollo Regional. Project EUROINNOVA EP-2 NANOCONS (IIM10784.RI1-02182).

This study reports the synthesis and characterization of ternary Cr-Al-O and quaternary Cr-Al-O-N coatings deposited by cathodic arc physical vapour deposition, for various nitrogen and oxygen mass flow ratios during the growth process. The composition, microstructure, indentation hardness and modulus of the films have been characterized by scanning electron microscopy, electron probe micro-analysis, X-ray diffraction, and nanoindentation techniques. The evolution of the microstructure and mechanical properties of the coatings after ambient air annealing from 800 °C up to 1100 °C have been investigated. As the oxygen to nitrogen mass flow increases, the as-deposited coatings exhibit lower hardness, higher roughness, lower crystallinity and a more marked columnar structure. At oxygen to nitrogen mass flow ratios bigger than 10/90, the coatings exhibit a stoichiometry of the type (CrAl)2+εO3−ε. Only the coatings with an oxygen to nitrogen mass flow ratio smaller than 10/90 retained nitrogen in their compositions. In all cases, the coatings developed a cubic fcc lattice structure. After annealing at 1100 °C the resulting microstructure showed a clear dependency upon the initial composition of the films. The evolution of the microstructure during the high temperature tests, as well as the analysis of the nanoindentation hardness, composition and thickness also provided valuable information about the combined effects of the thermal stability and the oxidation of the deposited coatings. This work has been funded by the Spanish Ministry of Economy and Competitiveness through the project PROTEOX MAT2013-45391-P. The European Commission is also acknowledged through the FP7-FOFNMP project MICROFAST under contract Nr 608720. The Research Group of Surface Engineering and Nanostructured Materials in the Universidad Complutense de Madrid also acknowledges financial support of the Spanish MINECO (project MAT2015-65539-P).

Plasma immersion ion implantation technology has been utilized to enhance the photocatalytic activity of the anatase phase of TiO thin films deposited by cathodic arc evaporation PVD. The main objective of this study is to shift the light absorbance of the titania in order to obtain antibacterial activity under visible light irradiation. TiO thin films, deposited on polished stainless steel AISI 304 and silicon wafers, were implanted with nitrogen ions (N/N ) at 20 kV energy and different temperatures between 250 and 350 °C. The antibacterial activity of nitrogen implanted titania coatings has been monitored for Escherichia coli under visible light irradiation. Additionally ultra violet/visible spectrophotometry tests have been carried out to measure the changes in the light absorbance of the doped films. Further characterization has been performed, including X-ray photoelectron spectroscopy, X-ray diffraction and glow discharge optical emission spectrometry. As a result of Nitrogen implantation, the light absorption peak shifted from ultra violet region (UV-A) to visible wavelength range, which led to an increase of the antibacterial efficacy under visible light irradiation., This work was developed in the framework of the industrial project ACTIONIC (IDI-20140-230-231) supported by the Ministerio de Economía y Competitividad (MINECO), through Centro Desarrollo Tecnológico Industrial (CDTI), and the Government of Navarra through the project DECOBAC.

In this work, a successful sequential co-implantation treatment of Cr+ and N2 + ions into electrodeposited nickel plates is presented. The goal of this treatment is the simultaneous enhancement of the wear resistance, mechanical stability and corrosion-protection properties of the Ni surfaces. The ion-implanted surfaces have been characterized by glow-discharge optical-emission spectroscopy, X-ray diffraction, nano-hardness, roughness, nano-wear and potentio-dynamic corrosion tests. It has been observed that the implantation of Cr+ or N2 + alone is not sufficient to achieve simultaneously the enhancement of both the wear-resistance and the corrosion-protection properties. Conversely, the sequential implantation of Cr+ and N2 + at 140keV and fluencies of 3×1017 and 1.5×1017ions/cm2 respectively, permits the formation of a functional surface capable of reducing both the corrosion rate and the wear rates, with respect to those exhibited by the un-implanted Ni surfaces.This treatment can be used to protect the surfaces of micro-embossing/stamping dies based on electroformed Nickel, as an alternative to other coating strategies. Furthermore, the ion implantation assures the non-modification of the net-shape and surface finish of these types of dies, which is of crucial importance when they are used for high-precision micro-texturing/imprinting applications. © 2011 Elsevier B.V.

This work reports on the growth and properties of Cathodic Arc Physical Vapor Deposition of low friction-coefficient CrCN coatings, as deposited on the basis of complementary carbon/nitrogen gradient concentrations through the film thickness. The coatings developed in this study exhibited friction coefficients ranging from 0.2 to 0.6, against 100Cr6 bearing steel, depending on the preparation conditions. Gradient CrCN films with COF of 0.35 and comparable mechanical strength to that of CrN were achieved. The adhesion rate of metallic elements such as Fe during the sliding process of CrCN coated tools on AISI316L steels were monitored using a pin-on-disc experimental set-up. The results demonstrated a low tendency of the gradient CrCN deposited films to pick up material from the AISI316L steels surfaces, in contrast to that found when using standard CrN cathodic arc PVD films.

The use of ion implantation as a surface treatment technology has been dominated by its applications to prevent wear and oxidation in metal alloys, although some early works already pointed out that ion implantation could also be effective as a surface treatment for other materials, including polymers. Further research has shown that low-dose implantation of energetic light ions could be very effective for improving properties such as hardness and wear resistance in many different polymers. Cross linking of polymeric chains due to ionization energy provided by the stopping process is the main mechanism to explain the changes in mechanical properties. According to this model the lighter the ion is, the stronger is the effect: hydrogen and helium ions would be the ideal options to be employed in the treatment of polymers. This paper presents the results obtained by helium implantation in ultra high molecular weight polyethylene (UHMWPE). He+ ions were at 90 and doses between 5 × 1015 and 2 × 1016 ions/cm2. Nitrogen was also implanted in separate samples, under the same conditions, as a reference. Universal Hardness was measured using micro indenter at a maximum load of 2 mN. The results clearly show a higher increase in hardness and surface elastic modulus for samples implanted with helium, in comparison to those implanted with nitrogen or unimplanted. The effect also increases with the dose, although it saturates at 1 × 1016 ions/cm2.

Cr, CrN, TiCr coatings have been investigated as potential anti-multipactor coatings. The coatings were synthesized by cathodic-arc reactive evaporation in Ar–N 2 atmosphere where the ion energy is controlled by substrate biasing. Chemical state analysis and surface composition were studied by X-ray photoemission spectroscopy (XPS), whereas bulk composition and depth profile were studied by glow discharge optical emission spectroscopy (GDOES). The surface morphology was studied by optical profilometry (OP) and scanning electron microscopy (SEM). The compositions of the coatings were CrN and Ti 40 Cr 60 and they were homogeneous in depth. Surface oxidation was higher in Ti 40 Cr 60 than in CrN. Coatings deposited at high negative bias show lower deposition rate and had lower surface roughness than those obtained at low bias. Secondary electron emission yield (SEY) was higher for CrN than for Ti 40 Cr 60 , both before and after low-energy Ar + ion bombardment. The SEY of Ti 40 Cr 60 (1.17 maximum) was clearly smaller than the others. The maximum yield, σ m , and the first crossover electron energy, E 1 , are the most important parameters, and ( E 1 / σ m ) 1/2 is a good figure of merit. This quantity was approximately 3 eV 1/2 for Cr and CrN and 4 eV 1/2 for Ti 40 Cr. After Ar + ion bombardment, the average value improved significantly to 8.9 eV 1/2 for Cr and CrN and 10.2 eV 1/2 for Ti 40 Cr 60 . The radio-frequency multipactor performance of these materials was simulated using the experimentally determined SEY parameters.

CrN multilayer coatings are possible replacements for hard chromium because of their good mechanical and chemical properties. This paper focuses on X-ray photoelectron spectroscopy (XPS) to study the mechanism of electrochemical stripping of multilayered Cr-N based coatings. The samples were produced by electron beam (e-beam) physical vapour deposition (PVD), on mirror polished M2 steel. Multilayers constituted three separate layers of CrN with intermediate interlayers of Cr (0.1 μm). The total coating thickness was in the range 4.5-5.5 μm. Under galvanostatic conditions, anodic oxidation of CrN leads to replacement of nitrogen in the CrN coating by oxygen, forming oxy-nitrides on the samples surface. Contrary to findings described by some authors, we have not detected Cr6+ in this research. © 2006 Elsevier B.V. All rights reserved.

Diamond-like carbon (DLC) coatings have found great applicability in the automotive industry because of their low friction coefficient and high wear resistance. Nevertheless, their tribological performance can be greatly reduced on soft substrates such as titanium alloys. The hard DLC coating cannot usually follow elastic and plastic deformation of the substrate without failing. In order to overcome this property mismatch between hard coating and soft substrate, triode plasma nitriding was applied as a pre-treatment to improve the mechanical properties of the Ti6Al4V alloy and further enhance the load support for the DLC coating. DLC and multilayered TiN/DLC, CrN/DLC CrAlN/DLC coatings were deposited onto “standard” and plasma nitrided Ti6Al4V substrates. Triode plasma nitriding increased the load-bearing capacity of the coating/substrate system, as higher critical adhesion loads were recorded for DLC coatings on plasma nitrided Ti6Al4V substrates. This treatment also reduced the wear rate of the DLC coating/substrate. Further load support and lower wear rates were achieved by using TiN, CrN and CrAlN as intermediate layers on plasma nitrided Ti6Al4V substrates.

Plasma nitriding of different substrates such as Ti6Al4V and AISI M2 steel was achieved by means of D.C. glow discharges assisted by thermionic emission (triode configuration). The higher ionisation levels achieved using a D.C. triode configuration reduced the treatment time and nitriding temperature required to obtain hard and reasonably deep nitrided cases in the Ti6Al4V alloy. For this alloy, surface hardness values of 560–600 HV 0.05 and nitrided layer depths of 30–40 μm were achieved at 700 °C. Up to this nitriding temperature, hardening seemed to be mainly accomplished by incorporation of nitrogen in the α-Ti phase, as the formation of a titanium nitride layer on the surface could not be detected by SEM. For the AISI M2 steel, hard (1379–1524 HV 0.05 ) nitrided layers of 100–150 μm were obtained at 480–500 °C for 240 min, depending on total pressure, gas composition and substrate bias. For the highest nitrogen concentration and lowest bias voltage, no compound layer was formed. The triode plasma nitriding process allowed a significant reduction in processing time for both M2 steel and Ti6Al4V alloy in comparison to conventional D.C. diode plasma nitriding.

This paper is focussed on the characterisation of electron beam evaporation plasma-assisted physical vapour deposition Cr–N coatings deposited on AISI M2 steel and hardmetal (K10) substrates in two different conditions: Pristine (i.e., coated) and Recoated (i.e., stripped and recoated). Analytical methods, including X-ray diffraction (XRD), scanning electron microscopy, scratch adhesion and pin-on-disc tests were used to evaluate several coating properties. XRD analyses indicated that both Pristine and Recoated coatings consisted of a mixture of hexagonal Cr2N and cubic CrN, regardless of substrate type. For the M2 steel substrate, only small differences were found in terms of coating phases, microstructure, adhesion, friction and wear coefficients between Pristine and Recoated. Recoated on WC–Co (K10) exhibited a less dense microstructure and significant inferior adhesion compared to Pristine on WC–Co (K10). The wear coefficient of Recoated on WC–Co was 100 times higher than those exhibited by all other specimens. The results obtained confirm that the stripping process did not adversely affect the Cr–N properties when this coating was deposited onto M2 steel substrates, but it is clear from the unsatisfactory tribological performance of Recoated on WC–Co that the stripping process is unsuitable for hardmetal substrates.

Cr–N benefits from good oxidation and corrosion resistance, which has, until recently, caused difficulties in removing the coating without damage to substrates. Consequently, the industrial use of Cr–N coatings, particularly on expensive tools, has been limited. As a new commercially viable wet-stripping process has been developed that causes little or negligible damage to steel substrates, it is appropriate to investigate the effect of coating thickness and structure on the stripping rate of different Cr–N films. In this work, Cr–N coatings deposited by magnetron sputtering, arc and electron beam evaporation, having different thicknesses, was wet-stripped. The stripping rate was evaluated by statistical analyses for each deposition method and thickness. The stripping rate for the various deposition methods was correlated to the coating phases, structure, morphology, and surface roughness, which varied depending on the deposition process. For all deposition methods, the stripping rate was constant at a given as-deposited coating thickness. Regardless of the deposition method, the stripping rate for all different as-deposited thicknesses was statistically similar within the same deposition process, indicating that the stripping rate was independent of the coating thickness. Moreover, the stripping rate was not influenced by changes in the coating structure with increased thickness, which occurred in arc and electron beam Cr–N coatings. For coatings having similar as-deposited thicknesses, the highest stripping rate was obtained in magnetron sputtered Cr–N (∼ 4.4 μm h − 1 ), followed by electron beam and arc Cr–N coatings, which displayed similar stripping rates (∼ 3.3 μm h − 1 ). The highest stripping rate recorded for magnetron Cr–N coatings could not be explained by changes in coating structure/morphology and surface roughness. The differences in the stripping were attributed to the amount of CrN phase present in the coatings.

This work reports a comparative investigation on tribological performance enhancement induced by nitrogen Plasma Immersion Ion Implantation (PI3) and conventional Nitrogen Ion Implantation (I2) on Ti and Al based alloys. The study has been carried out on the basis of the surface modification produced by both treatment techniques, in terms of the implanted nitrogen in-depth profiles, and its effect on surface hardening and wear resistance increase of the treated samples. Under the experimental conditions described, PI3 Ti-based alloys treated samples evidenced slightly better tribological performance than those subjected to I2 treatments. In the case of Al alloys, however, PI3 caused strong detrimental modification on the treated samples as revealed in the increase by a factor 100 of its surface roughness. Consequently, different criteria should be deemed in order to establish the adequacy of one or other technique, not only taking into account set up costs but also considering specific applications.

Recent breakthroughs in wet-stripping Physical Vapour Deposited (PVD) CrN coatings on standard high speed and stainless steels and on hard metal substrates are reported in this work. Validation of the stripping processes was evaluated in terms of substrate damage after exposure to the chemical agents and also in terms of the tribological properties of the PVD CrN layers before (Pristine) and after stripping and re-coating (Recoated). The investigation was focussed on the influence of the stripping process on the hardness, roughness, adherence and wear resistance of the Recoated CrN coatings deposited by electron beam PVD (e-beam) after stripping. Analysis of the chemically stripped and Recoated steel substrates showed that: (a) hardness and elastic modulus of the Recoated e-beam CrN did not change significantly compared to Pristine e-beam CrN, and (b) surface roughness of the Recoated e-beam CrN layers was greater by a factor of 50–60% than the initial. For hard-metal substrates, the surface damage and its effect on the re-deposited coating performance in terms of the chemical reactions during the stripping process were discussed. It was observed that wet-stripping in a basic solution led to depletion of tungsten and carbon at the surface of the stripped WC-Co specimens. D 2004 Elsevier B.V. All rights reserved.

This work reports on the preparation and characterization of hard (Ti,Si)N nanocomposite coatings as a function of composition and ion bombardment during growth. The energy delivered to the growing film was changed using both bias voltage change and solenoid coils placed between the targets and the substrate holder. The stoichiometry of the films was investigated by Rutherford backscattering spectrometry (RBS). With reduced energy delivered to the growing film and low deposition temperatures, the coatings developed an fcc Ti1xSixNy phase (a=0.416 nm in a sample with 18 at.% of Si) where some Si atoms are probably occupying Ti positions in the TiN1x matrix, and can be identified as a metastable phase. With higher levels of ion irradiation, an fcc TiN phase with higher lattice parameters was developed, and a significant increase in hardness was obtained. The enhancement in species mobility at the film surface is enough to ensure an effective phase segregation, leading to the formation of an nc-TiN/a-Si3N4 nanocomposite. In spite of the development of some degree of residual stresses, the overall results confirm the potential benefits of ion bombardment during film growth. The fact that these high compressive stresses can be released through thermal annealing in vacuum, keeping the coating hardness values of about 45 GPa even after thermal treatments at 900 8C, is an example of these benefits. D 2004 Elsevier B.V. All rights reserved.

In this contribution, we report on the structural and the tribological characterisation of low-energy nitrogen-ion-implanted Vanadium Titanium (V5Ti) alloys as a function of the annealing temperature during the bombardment process. The surface of the alloys was bombarded with N 2 + ions accelerated at 1.2 keV in a vacuum chamber equipped with a Kaufman-type ion source. The temperature during the low-energy ion implantation were 480, 500, and 575 °C. In this temperature range, the penetration depth reached by the implanted ions is not only exclusively ballistic (i.e., kinetic energy dependent), but diffusion effects also play a decisive role. The structural changes can be drawn as the formation of a nitrogen diffusion layer containing a blend of pristine bcc V5Ti and a solid nitrogen solution having an expanded bcc phase. It has been found that the temperature favours the increase of both, the thickness of the diffusion layer and the relative nitrogen content in the solid solution. We have investigated the microhardness, friction and wear coefficients of the implanted V5Ti surfaces as a function of the annealing temperature. The reported results indicate that both hardness and wear resistance against mechanical abrasion increase as the temperature during the bombardment increases. This increment of the hardness and wear resistance could be directly correlated to the amount of the expanded phase exhibited by the V5Ti surfaces, as observed by X-ray diffraction. The hardness and wear resistance modification upon annealing temperature are discussed in terms of the plastic deformation undergone by the expanded bcc phase to release the accumulated lattice stresses.

The present paper reports on the tribological analysis of high-performance magnetron sputtered metal-carbon multilayered coating WC:H/Cr, in particular on the effect of the different process parameters on the final coating properties. A detailed mechanical and tribological analysis in terms of hardness, elastic modulus, friction coefficient and wear coefficient for the different coatings have been carried out and discussed. The mechanical test have indicated an overall good tribological behaviour for all the deposited coatings. In particular, we have found that, when the deposition parameters are optimised, these present very low abrasive wear. In these conditions, we report wear coefficients as low as 10−16 m3/N m, which can be attributed to a combination of relative high hardness and very low roughness.

We have applied factor analysis to the study of the valence band resonant photoemission spectra of a TiO 2 thin film. Classical analysis of the photoemission spectra as a function of the photon energy through the Ti 2p → 3d absorption edge does not give a clear understanding of the resonant process, because the resonance phenomenon is present along the valence band and the only differences on the resonance are related to the distribution of cationic d-states. However, factor analysis of the spectra allows a more quantitative analysis of the resonance phenomena. Using theoretical partial Ti 3d and O 2p density of states as starting bases in principal component analysis, it is shown that only the hybridized Ti 3d states at the valence band resonate. The Ti 3d constant initial state (CIS) curve maps the Ti 2p x-ray absorption spectrum. Experimental relative photoemission cross-sections of the Ti 3d states at the absorption edge (455-470 eV) have been obtained. It is shown that resonant photoemission gives a sixfold enhancement of the Ti 3d cross-section at 463 eV with respect to the values at energies off-resonance.

Soft x-ray absorption spectroscopy (XAS) has been used to perform chemical analysis of oxide films formed after contact with air, both at room temperature and at 750° C, on three titanium alloys. The alloys investigated were Ti–13Nb–13Zr, Ti–15Zr–4Nb and Ti–7Nb–6Al. Soft x-ray absorption spectra were taken at the Ti 2p and O 1s edges. The spectra corresponding to the room-temperature-oxidized samples are similar for the three alloys and show the presence of native oxide with a small metallic contribution. For the heat-treated samples, the alloying elements as well as element diffusion play a significant role in the formation of the oxide layer. In this case, the spectra exhibit clear differences between the TiNbZr alloys and Ti–7Nb–6Al. The oxide layer of the two TiNbZr alloys for the different heat treatment times is composed of TiO2 in the form of rutile. However, for Ti–7Nb–6Al short heat treatments give rise to the formation of Al2TiO5. By increasing the oxidation time, an Al2O3 layer grows on the initial oxide film, becoming thicker as the exposure time is enhanced. Copyright © 2002 John Wiley & Sons, Ltd.

The stoichiometry, structure and mechanical properties of ion beam sputtered TiC x N y thin films have been studied as a function of the assistance conditions. Tuning the ratio between the current density of assisting N 2 + ions and the target sputtering rate allows us to achieve films with stoichiometries in the range of 0.6> x >0.25, keeping x + y ≈1. The surface topography is also sensitive to the assisting conditions where the RMS roughness is an increasing parameter as the ion beam bombardment increases. In terms of the Ar + ion beam assistance, the films undergo a significant amorphisation and a steep increase in lattice strain as the current density and energy of the impinging ions are increased. The observed changes are discussed in terms of the energy transfer of the bombarding Ar + ions to the layers below the surface of the growing films, leading to vacancies and defects and to a sharp decrease in film crystallinity.

The nano-hardness (HV) of TiCxNy (x+y≈1) thin films has been investigated by nano-indentation as a function of the ion beam assistance for different contact depths and annealing temperatures. The hardness at low indentation depths (i.e. 10 nm) is observed to decrease abruptly from 55 down to 26 GPa when the carbon content in the films decreases from x≈0.2 to x≈0.05 (∼TiN). On the contrary, hardness measured at penetration depths of 40 nm is observed to decrease very slightly. After annealing in UHV the hardness of the coatings becomes independent of the penetration depths. Moreover, the values of the hardness of the annealed coatings are similar to the values measured for the untreated coatings at high penetration depths. All this suggests that, the surface of the films are hardened significantly, and that this hardening can be reduced not only by annealing but also by increasing the ion beam bombardment during the growth process. The mechanism of the film hardening has been addressed in terms of the content of lattice defects and its dependence on the ion bombardment.

SUMMARY AND CONCLUSIONS Electron energy-loss functions of Ti, TiC, TiN and TiO 2 in the energy range 3–60 eV have been determined fromexperimental REELS spectra in terms of the model proposedby Yubero and Tougaard. 23 These ELFs have been used tocalculateelectronIMFPs foreachmaterialinthe250–2000 eVenergy range and as a function of the depth travelled by theelectron, ( E 0 , x ). In the limit of x × 1 , we obtain theusual IMFP for an infinite homogeneous medium. We haveintroduced REELS as a modified IMFP that includes surfaceeffects as they appear in REELS experiments. The differencesbetween 1 and REELS areobservedtobe¾0.2 nm forthe materials studied here. A comparison of the calculatedIMFPs with values predicted by the TPP-2M formula showsgood agreement for Ti, TiN and TiC (5–10% deviations) butdifferencesofupto40%forTiO 2 ,whichapparentlycannotbeassociatedwithuncertaintiesintheproposedELF.Ingeneral,for a determined primary energy the IMFPs are observed todecrease as the density of valence electrons increases, i.e.

We have studied the implantation of 2 keV N2+ ions in TiC. Both the shape and binding energy of the different core levels, as well as their modification, have been analysed during the implantation process. In order to quantify the implantation steps as a function of the N2+ dose, we have used a Monte-Carlo-based TRIM code to simulate the implantation profile of the nitrogen ions, except for the absolute atomic concentration, which is then determined by making use of the usual equations for quantitative XPS. We have derived the atomic concentration of implanted nitrogen atoms, i.e. N(z, DN), as a function of depth and the N2+ ion dose in terms of TRIM simulated in depth profiles and the usual equations for quantitative XPS analysis. Owing to the accumulation effect and the sputtering of the target surface, the static nitrogen profiles NN(z) derived by TRIM evolve to an erf(z) distribution with increasing ion dose DN. A proper analysis of the Ti 2p, C 1s and N 1s peaks also allows different species to be distinguished and their distribution in depth. Copyright © 2002 John Wiley & Sons, Ltd.

Amorphous carbon nitride thin films were prepared in a dual ion beam sputtering (DIBS) system. The N/C atomic concentration ratio ranged between 0.3 and 0.5 as determined by quantitative X-ray photoelectron spectroscopy (XPS) of the surface. Fourier Transform Infrared spectroscopy (FT–IR), XPS and X-ray Absorption Spectroscopy (XAS) were used to obtain information about the different types of bonding present in the films. The hardness and the Young's modulus of the samples were determined by nanoindentation measurements. The hardness varied in the range 15–30 GPa with Young's modulus between 170 and 250 GPa. In order to explain the measured hardness, some of the films are considered as heterogeneous, in good agreement with the XPS, FT–IR and XAS data.

In this work, dual implantation of Cr + and N 2 + ions on electroplated Ni substrates have been investigated for N 2 + implantation energies of 140keV, 100keV and 60keV. The implanted specimens have been analyzed by glow discharge optical emission spectroscopy, X-ray diffraction, nano-indentation, coefficient of friction, nano-wear and potentiodynamic corrosion curves. The properties of the dual implanted samples have been compared to Cr + or N 2 + implanted specimens.The microstructural and mechanical properties of the Ni plates depend on the penetration ranges of the Cr and N atomic profiles obtained after the implantation process. The increase of hardness reduced the coefficient of friction of the samples and the wear rates. Preferential formation of Cr-N over Ni-N compounds has been observed when the Cr and N atomic profiles coexist within the Ni matrix.The potentiodynamic corrosion curves in acidic solutions revealed that the presence of Me-N species is detrimental for the chemical stability of the plates. Both nano-wear and corrosion properties are optimized when a Ni-N sublayer is formed underneath a top Cr-Ni implanted film. This is achieved by tuning the implantation energies of Cr + and N 2 + ions at 140keV. This bilayer structure could be a suitable treatment for micro-embossing dies for plastic texturing processes. © 2012 Elsevier B.V.

We report the Ti 2p X-ray absorption (XAS) and resonant photoemission (RPES) spectra of one equivalent TiO2 monolayer grown on MgO, Al 2O3 and SiO2 substrates. The Ti 2p XAS spectra of these systems were compared to atomic multiplet calculations projected in different octahedral crystal fields. The comparison indicates that the crystal field splitting and the Ti-O hybridization decrease along the MgO, Al 2O3 and SiO2 series. The analysis of the RPES spectra provides the Ti 3d contributions to the valence band in these systems. These were compared to configuration interaction calculations of a TiO 6 cluster for different Ti 3d-O 2p hybridizations. The Ti 3d states in the valence band shift to lower binding energies along the MgO, Al 2O3 and SiO2 series. These effects are attributed to changes in the electronic structure at the interface, which, in turn, are related to the formation of cross-linking Ti-O-M (M = Mg, Al, and Si) bonds. © 2010 Elsevier B.V. All rights reserved., This work has been financially supported by the Spanish Ministerio de Ciencia e Innovación (MICINN) through contracts FUNCOAT-CSD2008-00023, MAT2007-66719-C03-03 and MAT2008-01497. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 226716.

We have studied the early stages of growth of the layers formed by Ni evaporation in an oxygen atmosphere at room temperature on a Cu(111) single crystal. The layers have been analysed by XPS and x-ray absorption spectroscopy as a function of the deposition time. A background analysis of the XPS spectra has also been performed. We have found a Stranski-Krastanov way of growth, i.e. the formation of a metallic Ni monolayer followed by the formation of defective NiO islands. Further deposition leads to the formation of stoichiometric NiO.