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The thermal stability of two AlyTi1- y(OxN1-x) layers prepared by cathodic vacuum arc deposition with different oxygen content was studied after high temperature annealing of the samples in air. These layers were designed to be part of solar-selective coating (SSC) stacks. Compositional and microstructural characterization of the thin films was performed before and after the thermal treatment by elastic recoil detection (ERD), transmission electron microscopy, and Raman spectroscopy. AlyTi1- yN sample was stable after 2 h of annealing at 450 °C. Initial stages of the formation of a surface oxide layer after annealing at 650 °C were observed both by ERD and Raman analysis. Contrarily, no changes were found after 2 h annealing treatment either at 450 and 650 °C in the composition and microstructure of AlyTi1- y(OxN1-x) sample. In both samples, the formation of a surface anatase TiO2 film was reported after 2 h annealing at 800 °C. These compositional and microstructural changes were correlated with the optical properties determined by spectroscopic ellipsometry. A transition from metallic to dielectric behavior with increasing annealing temperature was observed. These results complete the durability studies on the designed SSC based on AlyTi1- y(OxN1-x) materials, confirming that these stacks withstand breakdown at 600 °C in air. H2020 RISE project “Framework of Innovation for Engineering of New Durable Solar Surfaces GA-645725 Spanish Ministry of Science and Innovation project “Recubrimientos innovadores preparados por magnetron sputtering para absorción solar selectiva" PID2019-104256RB-I00 Agencia Estatal de Investigacion (AEI) project “Entrenamiento avanzado en materiales para superficies solares duraderas EIN2020-112163 /AEI/10.13039/501100011033

Two multilayer solar selective absorber coatings [Al/CrN0.95/Cr0.96Al0.04N1.08/Cr0.53Al0.47N1.12/Al2O3 (stack #1) and Cr0.96Al0.04N0.89/Cr0.62Al0.38N1.00/Cr0.53Al0.47N1.12/Al2O3 (stack #2)] were deposited on 316L steel by combining direct current (DC) and high power impulse magnetron sputtering (HiPIMS) technologies with the aim of increasing the working limit temperature. The composition and thickness of the constituent layers were optimized using CODE software to achieve a high solar absorptance (α) and low values of thermal emittance (ɛ) in the infrared region. The deposited multilayered stacks were heated during 2 hours in air at 600, 700 and 800 ºC to study their thermal stability and optical performance. Compositional, structural and optical characterization of the stacks (as-prepared and after thermal treatment) was performed. Both stacks presented a good solar selectivity with  > 95% and 25 ºC < 15%, were stable up to 600 ºC and fulfilled the performance criterion PC < 5% after 600 and 700 ºC treatments. Despite the stacks suffered chemical transformations above 600 ºC, partial oxidation (stack #1) and Cr2N formation (stack #1 and #2), the optical properties were optimum up to 700 ºC for stack #1 (α = 94%, ε(25 ºC) =12%) and 600 ºC for stack #2 (α = 93%, ε25 ºC =13%).The solar-to-mechanical energy conversion efficiencies () of the as-deposited and annealed (600 and 700 ºC) samples were up to 20 percentage points higher than the absorber paint commercially used (Pyromark). At 800 ºC, they underwent a further structural transformation, provoked by the oxidation of the inner layers, and they consequently lost their solar selectivity.

International audience; It has been shown recently that the perovskite oxide SrVO 3 is a transparent conductor with optical and electrical properties outreaching those of the most used material indium tin oxide (ITO). These properties, observed in the crystalline phase, imply the strong potential of SrVO 3 for use as a lower cost alternative to ITO, but the possible integration of this perovskite oxide material in actual electronic devices is still an open question. One of the possible approaches for the integration of oxide materials is the use of amorphous thin films, allowing low thermal budgets to preserve the performances of the electronic device. Therefore, in this study, the electrical and optical properties of amorphous or poorly crystallized thin SrVO 3 films are investigated.

Solar selective coating multilayers deposited by magnetron sputtering and containing Mo:Si 3 N 4 cermet as the absorber layer and Ag as infrared reflector (IR-mirror) have shown excellent optical characteristics for concentrated solar power applications at high temperatures. However, mechanical reliability of such optical coatings is a concern due to the large thermal mismatch between the Mo:Si 3 N 4 cermet and the Ag IR-mirror layer. The substitution of the Ag IR-mirror layer by a Ti/Ag bilayer can improve mechanical reliability at the operating conditions, but at the expense of deteriorating the optical properties of the solar selective coating. In this work, we study the evolution of the mechanical and optical properties of Mo:Si 3 N 4 /Ti/Ag solar selective coatings, as a function of the Ti/Ag ratio, with the objective of finding a compromise between the optical and mechanical properties. The substitution of Ag by Ti improves the multilayers scratch resistance without deteriorating the optical properties. As a result, we suggest an optimal composition of the Ti/Ag IR-mirror bilayer.

The oxidation resistance of CrAl(Y)N coatings deposited by reactive magnetron sputtering on P92 steel substrates was tested at 650. °C in 100% steam atmosphere up to 2000. h of oxidation. Mass gain measurements and characterisation of coatings and scales after oxidation show the enhanced oxidation resistance provided by the coatings with respect to that of the substrate. The dominant influence of the film microstructure developed due to the presence of an adhesion interlayer of CrN at the coating/substrate interface over Y additions is evidenced. The best performance is achieved by a CrAlN dense coating of around 6. μm without adhesion interlayer. © 2013 Elsevier Ltd., The authors gratefully acknowledge the financial support of the Spanish MINECO (projects Consolider FUNCOAT CSD2008-00023 and NANOPROTEXT MAT2011-29074-C02-01/02). Dr. R. Escobar Galindo acknowledges financial support through Ramon y Cajal Spanish programme (RyC2007-0026).

(Bi0.5Na0.5)1-xBaxTiO3 (BNBT), which exhibits compositions for the morphotropic phase boundary (MPB) where exist an intimate coexistence of the rhombohedral and tetragonal structures, is being considered as promising lead-free alternative to the well known Pb(Zrx,Ti1-x)O3 (PZT). In this work, BNBT thin films were fabricated by chemical solution deposition (CSD) with a wide range of compositions (x~0.050-0.150) onto Pt/TiO2/SiO2/(100)Si substrates. Structural studies by X-ray diffraction (¥eCu~1.5406 A) using a four-circle goniometer were carried out to determine the crystalline structure of the films. Rietveld analysis of the experimental X-ray patterns showed different volume fractions of the rhombohedral and tetragonal phases as a function of the Ba2+ content and the coexistence of both phases, characteristic of a MPB region, for xi­0.055-0.080. Finally, Rutherford backscattering experiments (RBS) were performed to determine the compositional profile of the films. This study revealed a homogenous composition of the BNBT films with abrupt film/substrate interfaces.

Surface modification by means of wear protective and antibacterial coatings represents, nowadays, a crucial challenge in the biomaterials field in order to enhance the lifetime of bio-devices. It is possible to tailor the properties of the material by using an appropriate combination of high wear resistance (e.g., nitride or carbide coatings) and biocide agents (e.g., noble metals as silver) to fulfill its final application. This behavior is controlled at last by the outmost surface of the coating. Therefore, the analytical characterization of these new materials requires high-resolution analytical techniques able to provide information about surface and depth composition down to the nanometric level. Among these techniques are Rutherford backscattering spectrometry (RBS), glow discharge optical emission spectroscopy (GDOES), and angle resolved X-ray photoelectron spectroscopy (ARXPS). In this work, we present a comparative RBS-GDOES-ARXPS study of the surface characterization of Ag-TiCN coatings with Ag/Ti atomic ratios varying from 0 to 1.49, deposited at room temperature and 200 C. RBS analysis allowed a precise quantification of the silver content along the coating with a non-uniform Ag depth distribution for the samples with higher Ag content. GDOES surface profiling revealed that the samples with higher Ag content as well as the samples deposited at 200 C showed an ultrathin (1-10 nm) Ag-rich layer on the coating surface followed by a silver depletion zone (20-30 nm), being the thickness of both layers enhanced with Ag content and deposition temperature. ARXPS analysis confirmed these observations after applying general algorithm involving regularization in addition to singular value decomposition techniques to obtain the concentration depth profiles. Finally, ARXPS measurements were used to provide further information on the surface morphology of the samples obtaining an excellent agreement with SEM observations when a growth model of silver islands with a height d = 1.5 nm and coverage θ = 0.20 was applied to the sample with Ag/Ti = 1.49 and deposited at room temperature., This work was financially supported by the Spanish Ministry of Science and Innovation (projects FUNCOAT CSD2008-00023 and RyC2007-0026). This research is sponsored by FEDER funds through the program COMPETE “Programa Operacional Factores de Competitividade” and by national funds through FCT “Fundação para a Ciência e a Tecnologia”, in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, and PEST-C/EME/UI0285/2011 and under the project PTDC/CTM/102853/2008.

This paper is focused on the sputtering process and on the structure, chemical composition and mechanical properties of coatings consisting of Al O dielectric matrix incorporated with increasing Au contents. The maximum Au content incorporated in the coatings was 9 at.%. Al was in deficient values in relation to the Al 2 O 3 compound. Al O matrix is amorphous irrespectively of the annealing temperature and no signs of Au crystals were detected in the as-deposited films. Segregation of small Au clusters was found in the high Au content coatings after annealing at increasing temperatures. Hardness values were in the range 11–13 GPa irrespectively of the Au content and the annealing treatments. Au clustering in the dielectric matrix, which could be able to promote surface plasmon resonance effect, associated with good mechanical properties of the Al O matrix, make envisaging the application of these coatings in decorative fields.

The development of mixed-oxide thin films allows obtaining materials with better properties than those of the different binary oxides, which makes them suitable for a great number of applications in different fields, such as tribology, optics or microelectronics. In this paper we investigate the deposition of mixed chromium and silicon oxides deposited by reactive magnetron sputtering with a view to use them as optical coatings with an adjustable refractive index. These films have been characterized by means of Rutherford backscattering spectrometry, Auger electron spectroscopy, X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy and spectroscopic ellipsometry so as to determine how the deposition conditions influence the characteristics of the material. We have found that the deposition parameter whose influence determines the properties of the films to a greater extent is the amount of oxygen in the reactive sputtering gas.

In this work, we have studied the improvement on the oxidation resistance of AlCrN-based coatings by adding a subsurface titanium nitride barrier layer. Since oxidation is interrelated with the inward diffusion of oxygen into the surface of AlxCr1−xN (x = 0.70) coatings and the outward diffusion of Cr to the surface, the oxidation behaviour of the aluminium-rich AlCrN coatings can be tuned by designing the coating in an appropriate layered structure. The buried depth of the embedded layer and the oxidation time were varied, and the changes in the AlCrN/TiN depth composition profiles and surface oxidation stoichiometry were analysed by means of Glow Discharge Optical Emission Spectroscopy (GDOES) and Cross Sectional SEM (X-SEM) maps. It was observed that when a TiN diffusion barrier of 300 nm was deposited near the top surface (500 nm from the surface) the inhibition of the inward diffusion of oxygen and formation of beneficial alumina surface layers was promoted and consequently an increase of the oxidation resistance is achieved. This is explained in terms of a limited surplus of chromium from the coating to the surface. This was corroborated after performing experiments using CrN as embedded barrier layer which resulted in a continuous surplus of chromium to the surface and the formation of Cr-rich oxides. GDOES, in combination with X-SEM elemental maps, was proved to be a fast and accurate technique to monitor composition in-depth changes during oxidation, providing unique information regarding the oxide structure formation.

We have investigated the relation between the structure and morphology of TiN coatings with their optical properties. Samples were deposited by magnetron sputtering and, by changing the deposition parameters, different textures and chemical compositions can be obtained as measured by X-ray diffraction and glow discharge optical emission spectroscopy respectively. The transmittance in the visible range, measured by spectroscopic ellipsometry, and the emittance, derived from reflectance in the far infrared range as measured by Fourier Transform Infrared Spectroscopy have been related to the nitrogen atomic content and the preferred crystalline orientations present in the TiN coatings. The visible transmittance of the coatings was found not to be dependent on the preferential orientation, while the emittance clearly improves with increasing the film thickness and the presence of both (111) and (200) crystal orientations.

Ti-doped In 2 O 3 (ITiO) thin films have been prepared by electron beam physical vapour deposition (EB-PVD). Their optical and electrical properties are studied for the obtained compositions. After oxygen annealing all samples show excellent optical transparence; additionally, maximum values for conductivity are obtained for samples with titanium contents near 6 at.%, with typical resistivity values of 4 x 10 -5 Ω cm. Finally, the band-gap energy evolution is studied for the set of samples.

In this study, cemented carbide ball nose end mills with nano-crystalline Al 0.67 Ti 0.33 N hard PVD coatings deposited by cathodic arc evaporation were annealed at 700 °C during 2 h in a controlled atmosphere environment (argon + oxygen mixture) and in vacuum. The changes of structure and properties of the treated coating surfaces have been analyzed using both cross-sectional scanning electron microscopy (SEM) and x-ray absorption spectroscopy (XAS) of the N–K and O–K edges. Cutting tools have been run through ball nose end milling of hardened H13 steel (HRC 50) where temperature or stress dominating phenomena control tool life. The data obtained indicate that an AlTiN coated cutting tool can be modified upon annealing at low temperature conditions and should be considered as a composite surface engineered material. It is shown that increased tool life could be achieved if annealing of AlTiN is performed in an oxygen-containing atmosphere. A variety of different characteristics should be optimized to achieve better wear resistance of the cutting tools with annealed Al 0.67 Ti 0.33 N coating under high temperature and stress cutting conditions.

We examine here the depth resolution (interface width) in elemental analysis and depth profiling of complex layer systems of three ion-probing techniques, each of which has pros and cons: • Rutherford backscattering spectrometry (RBS); • secondary ion mass spectroscopy (SIMS); and, • glow-discharge optical emission spectroscopy (GDOES). RBS is a non-destructive technique that requires no standards for quantification, although access to medium-scale ion-source facilities is needed. SIMS maintains nanometer (nm) resolution at greater depths but at the expense of longer data-acquisition times. Finally, GDOES allows depth profiling quickly and accurately, although depth resolution degrades linearly with depth due to sputtering effects (e.g., crater shape and chemical modifications), among other factors. We discuss these ion-probing techniques in the light of new results obtained with chromium/titanium multilayer structures with individual layer thicknesses between hundreds of nm and a few nm. We resolved ultra-thin chromium layers of 2.5 nm and 5 nm, buried at different depths in titanium matrixes with thicknesses up to 3 μm, and used the results to evaluate the depth resolution of the ion-probing techniques.

The boron diffusion in the Fe2B and FeB borided phases formed at the surface of AISI H13 tool steels during the paste boriding process was estimated. The treatment was carried out at temperatures of 1173, 1223 and 1273 K with 2, 4, 6 and 8 h exposure times for each temperature using a 4 mm layer thickness of boron carbide paste over the material surface. The boride layers were characterized by the GDOES technique to determine in quantitative form the presence of the alloying elements on the borided phases. The boron diffusion coefficients and were determined by the mass balance equation and the boride incubation time assuming that the boride layers obey the parabolic growth law. Also, the mass gain produced by both boride layers at the surface of the tool steels was determined. Finally, the boron diffusion coefficients were interpreted as a function of the treatment temperature, obtaining the activation energy values for the diffusion controlled growth of Fe2B and FeB hard coatings.

Forma parte de número especial: Proceedings of the 35th International Conference on Metallurgical Coatings and Thin Films Ti–Si–C–ON films were deposited by DC reactive magnetron sputtering using different partial pressure ratio of oxygen (pO2) and nitrogen (pN2). Compositional analysis revealed the existence of three different growth zones for the films; (I) N/Ti = 2.1 (high atomic ratio) and low oxygen content; (II) 0.76 < N/Ti < 2.1 (intermediate atomic ratio) and (III) N/Ti ≤ 0.12 (low ratio) and high oxygen content. For high N/Ti atomic ratio (N/Ti = 2.1) the XRD pattern exhibits reflections that correspond to a mixture of two different phases: a metallic-like Ti and a fcc NaCl type structure. Its electrical resistivity presents a metallic character and, consequently, has high infrared reflectivity. For the intermediate N/Ti ratio (0.76 < N/Ti < 2.1), the films crystallize in a B1-NaCl crystal structure typical for TiC0.2N0.8. Their FTIR spectra present C–N modes, besides the TiN ones, that indicate a progressive substitution of nitrogen by carbon atoms with increasing oxygen content (and lowering N/Ti ratio). For the highest oxygen content (and lower N/Ti ratio) the presence of the Ti–O–Ti stretching mode shows the formation of highly resistive Ti–O compounds consistent with the semiconductor character of this film. Biofilm formation as well as material cytotoxicity seemed to be related with the presence of the Ti.

Elemental in-depth analysis of the Y–Pd thin film under hydrogenation/dehydrogenation has been performed by Glow Discharge Optical Emission Spectroscopy (GDOES). This technique was able to detect qualitatively the changes in the composition of the layer, particularly the in-depth H and O distribution during hydrogen uptake and release. The charge of the film with hydrogen was done under electrochemically controlled conditions, while the discharge was effectuated in different modes: electrochemically, in alkali electrolyte (forced anodic discharge) or spontaneously, in air ambient or in the electrolyte (open potential circuit discharge). In-depth GDOES profiles of hydrogen at different times during the charge/discharge process confirm the processes of capture/release of hydrogen into the film corresponding to a reversible transition between the two hydrogenation states of yttrium: di- and tri-hydrides. The study of the oxygen profile reveals the presence of this element in the as prepared films and demonstrates its further accumulation under cyclic hydrogenation/dehydrogenation. Anodic discharge of the electrode rapidly increases oxygen content and probably leads to the formation of hydroxides along the whole yttrium depth with the consequent deterioration of the optical switching properties.

The broadening effects found in the depth profiles of abrupt periodic multilayers obtained by Glow Discharge Optical Emission Spectroscopy (GDOES) have been modelled by assuming that the resulting absolute concentration profiles can be described by Gaussian functions of constant area (equal to that of the cross section of the individual layers) and decreasing amplitude. The full width at half maximum (FWHM) of these functions has been assumed to increase with depth z according to a power law of the type: FWHM ( z ) = a + bz c , using for a and c , values estimated from previous works. In this model, the parameter b , defining the broadening and degradation of the layer interfaces, is obtained by fitting the experimental profiles with the theoretical spectra. We have found a correlation between b and the erosion rate of the material layers. In general, the model properly describes the depth profiles of multilayer structures made of alternating Ti and Cr layers in the nanometre range, and can be an useful tool to explain the profiles of more complex systems.

A mechanical characterization study of the whole range (ZrO2)1-x-(Y2O3)x system is presented for thin film samples. Films have been prepared by Electron Beam Physical Vapour Deposition (EB-PVD) on Si(1 0 0) substrates. The mechanical characterization, obtained from nanoindentation and Brillouin Light scattering (BLS) techniques, shows a monotonous behaviour between the two pure compounds of the series except for the film with 0.08 Y2O3 molar content of yttria-stabilized zirconia (YSZ) solid solution that presents an anomalous hard value. Additionally, BLS is presented as an alternative technique to the study of the mechanical properties of this system. © 2007., This work has been supported by Spanish DGICYT under contract No. MAT2003-6147-C04-01&02. J.G.L. acknowledges the “Ramón y Cajal” program of the Spanish MCyT for financial support.

Novel CrTiAlN multilayered nanocomposite thin films have been developed. They consist of alternating CrN and TiAlN layers of 10–12 nm individual thickness, up to a total thickness of 1– 3 μ m . These coatings were grown on WC-Co insets and high-speed steel samples by simultaneous arc evaporation (physical vapour deposition, PVD) of pure Cr and Ti-Al alloy targets. Wear resistance of these coatings was studied through high temperature pin-on-disk experiments. Results demonstrate that this kind of coating structures improves several times the wear resistance at high temperature of commercially available TiAlN coatings.

In this work, we have studied the influence of the coating design and composition on the oxidation behavior of Al x Cr 1− x N ( x = 0.70) coatings. In particular, we have studied the effect brought about by the deposition of an additional subsurface titanium nitride barrier layer as well as by the doping of the AlCrN-based coatings by tungsten, boron and silicon. The coatings studied have been deposited using the cathodic arc vacuum (CAV) technique. The multilayered AlCrN/TiN coatings with TiN sublayer were oxidized in air at 900 °C over 3 h and then analyzed by Glow Discharge Optical Emission Spectroscopy (GDOES) and X-ray photoelectron spectroscopy (XPS). Oxidation tests were performed in air at 900 and 1100 °C for the AlCrN and AlCrWN, AlCrSiN, and AlCrBN coatings. In each case weight gain was measured and the surface morphology of the oxidized samples were studied using Secondary Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The results obtained showed that the oxidation behavior of the aluminum rich AlCrN-based coatings could be improved in two ways: (1) by controlling the chromium outward diffusion rate in multi-layered coatings and (2) by alloying the AlCrN-based coatings with Si. Both improvements are related to the enhancement of the protective oxide film formation.

The total emissivity of the absorbing surfaces is a critical parameter in the calculation of the radiative thermal losses in solar thermal collectors. This is because the radiative heat losses have a significant economic impact on the final cost of the electricity produced in a solar thermal plant. This paper demonstrates the need to calculate the total emissivity from spectral emissivity measurements at the working temperature of the solar thermal collector, instead of using extrapolated values from spectral emissivities measured at room temperature. Usual uncertainties produced by the estimation of the total emissivity, in which its temperature dependence is only introduced by the Planck function, are analyzed., This work has been carried out with the financial support of the ETORTEK and SAIOTEK 2013 program (Project numbers S-PC08UN07 and S-PE13UN123 respectively) of the Basque Government in collaboration with CIC-Energigune. T. Echániz acknowledges the Basque Government their support through a Ph.D. fellowship.

Nowadays, antibacterial properties are becoming a viable feature to be introduced in biomaterials due to the possibility of modifying the materials' surface used in medical devices in a micro/nano metric scale. As a result, it is mandatory to understand the mechanisms of the antimicrobial agents currently used and their possible failures. In this work, the antibacterial activity of ZrCN–Ag films is studied, taking into consideration the ability of silver nanoparticles to be dissolved when embedded into a ceramic matrix. The study focuses on the silver release evaluated by glow discharge optical emission spectroscopy and the effect of the fluid composition on this release. The results revealed a very low silver release of the films, leading to non-antibacterial activity of such materials. The silver release was found to be dependent on the electrolyte composition. NaCl (8.9 g L− 1) showed the lowest spontaneously silver ionization, while introducing the sulfates in Hanks' balanced salt solution (HBSS) such ionization is increased; finally, the proteins incorporated to the (HBSS) showed a reduction of the silver release, which also explains the low ionization in the culture medium (tryptic soy broth) that contains high quantities of proteins., This research is partially sponsored by the FEDER funds through the program COMPETE — Programa Operacional Factores de Competitividade and by the Portuguese national funds through FCT—Fundação para a Ciência e a Tecnologia, under the projects ANTIMICROBCOAT — PTDC/CTM/102853/2008 and in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, PEST-C/EME/UI0285/2011 and SFRH/BD/80947/2011. This work has also been supported by the Ministerio de Ciencia e Innovacion of Spain through the Consolider-Ingenio 2010 Programme (CSD2008-00023) and through project RyC2007-0026.

Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr + Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5 % (w/v) NaClO solution for 5 minutes. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at. % of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the films surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release., IF acknowledges the financial support of FCT-Fundacao para a Ciencia e a Tecnologia through grant SFRH/BD/71139/2010.This research is partially sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the projects ANTIMICROBCOAT-PTDC/CTM/102853/2008 and in the framework of the Strategic Projects PEST-C/FIS/UI607/2011, and PEST-C/EME/UI0285/2011.The authors thank the FCT Strategic Project PEST-OE/EQB/LA0023/2013 and the Project "BioHealth-Biotechnology and Bioengineering approaches to improve health quality", Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER. The authors also acknowledge the project "Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB", Ref. FCOMP-01-0124-FEDER-027462.

In this work, we address the capability of glow discharge optical emission spectroscopy (GDOES) for fast and accurate depth profiling of multilayer nitride coatings down to the nanometer range. This is shown by resolving the particular case of CrN/AlN structures with individual thickness ranging from hundreds to few nanometers. In order to discriminate and identify artefacts in the GDOES depth profile due to the sputtering process, the layered structures were verified by Rutherford backscattering spectrometry (RBS) and scanning electron microscopy (SEM). The interfaces in the GDOES profiles for CrN/AlN structures are sharper than the ones measured for similar metal multilayers due to the lower sputtering rate of the nitrides. However, as a consequence of the crater shape, there is a linear degradation of the depth resolution with depth (approximately 40 nm/μm), saturating at a value of approximately half the thickness of the thinner layer. This limit is imposed by the simultaneous sputtering of consecutive layers. The ultimate GDOES depth resolution at the near surface region was estimated to be of 4–6 nm.

In this paper we present the first combined Positron Beam Analysis (PBA) and Environmental Scanning Electron Microscopy (ESEM) adhesion study on thin chromium nitride (CrN,) coatings. Both techniques are combined with a 4-point bending stage. PBA monitors the creation of open volume in the ceramic/metal interface prior to delamination while ESEM observations provide a picture of the delamination process itself. By varying the positron implantation energy, the coating layer or the coating/substrate interface can be studied separately. Coatings of 500 nm thickness were deposited via a physical vapour deposition (PVD) process on different types of steel and on polycrystalline copper. Samples were studied as deposited, after 30 min annealing at 973K, and during the 4-point bending test, respectively. After annealing the PBA results have changed depending on the substrate and the treatment. The positron S parameter associated to the nitride coating increases over the whole layer for samples deposited on tool steel and polycrystalline copper. In the case of the CrN layers deposited on interstitial free steel, there is a lower S parameter in the first 75 nm of the coating. This 2-layer structure inside the coating is more pronounced if the substrate is implanted with metal ions prior to the deposition. The positron parameter changes observed ill the coatings after annealing are confirmed by ESEM observations and it is related to the structural changes in the coating. The S value ascribed to the interface increases in all samples after the annealing process confirming the creation of open volume at the interface. The 4-point bending tests revealed a plastic deformation of the coating deposited on the soft IF substrate and a brittle delamination of the film when deposited on the hard tool steel. (c) 2005 Elsevier B.V All rights reserved.

Thin coatings of poly-ethylene terephthalate (PET) on metal (“laminates”) have been studied with a variable energy positron annihilation technique. A correlation between PET crystallinity and the positron annihilation parameter S related to the free volume in the polymer is found. It is shown that buried interfaces in these systems may be detected provided the S parameter of the polymer coating is lower than that of the substrate and higher than that of the surface. Also it is found that large positron diffusion lengths in the substrate favour interface detection. Further, changes in S parameter of PET–metal laminates were measured during uniaxial deformation and shown to be in qualitative accordance with a very simple model description that accounts for changes in free volume in PET during plastic deformation as well as the area fraction of cracks occurring in the PET.

A modified blister test has been developed based on helium ion implantation into selected areas of the metal substrate prior to the coating deposition. After a post-deposition thermal annealing, blisters are formed by agglomeration of the implanted gas at the ceramic-metal interface. This method can be used to control the pressure in the blister which eventually may lead to delamination at the periphery of the blister. A microsieve with a regular array of circular holes is used during the implantation to assure the initial blister size. Two different microsieves were employed in this work, with pore diameters of 1.5 and 4.5 mum, respectively. The distance between the centres of neighbour pores is twice the pore diameter. Scanning Electron Microscopy (SEM) and Confocal Scanning Optical Microscopy (CSOM) observations allowed the determination of the blistering parameters such as the radius, the height and the blister volume. From the gas content and these parameters, the work of adhesion or energy release rate can be obtained.In this work, we present the first results of this blister test applied to W-C:H films and multilayers of Ti and Al deposited by Physical Vapour Deposition on polycrystalline copper substrates. The copper substrates were implanted with 34 keV He+ ions up to fluences of 3 and 5 x 10(16) cm(-2) before the deposition of the coatings and annealed afterwards in vacuum at temperatures from 773 to 1073 K for 30 min. Delamination of the Ti/Al multilayer coatings was already detected after annealing at 873 K with an energy release rate estimated to be 0.5 J m(-2) at a typical helium pressure of 10(7) Pa. No delamination but only helium swelling was observed for W-C:H coatings annealed at 1073 K. Results of experiments on uncoated copper samples are also shown in order to explain the mechanism of helium bubble growth and helium release that causes the creation of the blisters. (C) 2004 Elsevier B.V. All rights reserved.

Parte del número especial: Proceedings of the 7th International Conference on Positron and Positronium Chemistry Depth-selective 2D-ACAR investigations on ordered mesoporous silica thin films provide direct evidence that para-positronium (p-Ps) created deep in the films can escape through a network of interconnected pores. The depth dependence of the escape fraction and of the average kinetic energy of non-thermally excited p-Ps is in quantitative agreement with Monte Carlo modeling, assuming classical collisions of p-Ps with the pore walls. The model provides insight in the shape of the angular correlation distributions and their sensitivity to, e.g., the effective wall mass Ms and pore dimensions.

Parte del número especial: E-MRS 2002 Symposium E: Advanced Characterisation of Semiconductors Non-destructive Doppler Broadening (DB), Positronium fraction (f-Ps) and Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR), Positron Beam Analysis (PBA) techniques have been used to study well-ordered mesoporous silica thin films with hydrophobic or hydrophilic character. The DB results, characterized by the S and W parameters, are related to both the open volume and the chemical environment at the positron annihilation site. The f-Ps and 2D-ACAR techniques are very sensitive probes to determine the type of porosity (open or closed in terms of positronium escape) in thin film materials. Samples with varying pore size (well-controlled at 2, 3 and 4.5 nm, or incorporating microporosity in the silica), pore fraction (from 4 to 57%) and extent of hydrophilicity have been studied. In the hydrophilic samples with small pore size the S-parameter increases with the porosity while the Ps-fraction remains almost unchanged. Increasing the pore size leads to smaller changes in S with increasing porosity. However, an abrupt change in the Ps-fraction is observed for samples with porosity higher than 45%, indicating a positronium percolation threshold for samples with 2D ordering structure. On the other hand, for hydrophobic samples with high porosity (57%) the highest S parameter and Ps-fraction were obtained for the three pore sizes studied. 2D-ACAR is used to determine the fraction and velocity of Ps escaping from some of the latter samples exhibiting positronium percolation. The relationship between these observations and porosity will be discussed in terms of branching of the positron annihilation channels inside the mesoporous films.

Positron beam techniques have been employed to characterise low-k dielectric silica based films, which have two or three dimensional structures of nanometre size pores. Pore fractions vary from 5 to 50%. Positrons implanted in the layer slow down and eventually annihilate with the electrons from the layer. However, in pores of the dielectric films positronium (Ps) is formed before annihilation takes place. The two states of Ps (para-positronium (p-Ps) and ortho-positronium (o-Ps)) are formed with rather different life times of 125 ps and 142 ns, respectively. The behaviour of Ps in the porous material can be described as hot particles with 1 eV initial kinetic energy, which lose their energy by frequent collisions with the atoms of the pore walls. When the pores are interconnected or separated by thin walls allowing permeation of the Ps some of the Ps will effuse from the film into the vacuum. The 2D-ACAR technique enables one to monitor the velocity distribution of the annihilating p-Ps and shows an increasing fraction of surface emitted p-Ps when positrons are implanted closer to the film surface. Measurements of Doppler broadening of 2-gamma annihilation and detection of 3-gamma events (o-Ps) give insight into the frequency of other annihilation events. Combining the results, a complete picture can be obtained of the interactions and transport of the Ps particles in the material. By modelling the Ps behaviour information is obtained on structural parameters of the porous material. A transport model based on multi energy group diffusion of particles describes the results well.

The main requirements for transparent conducting oxide (TCO) films acting as electrodes are a high transmission rate in the visible spectral region and low resistivity. However, in many cases, tolerance to temperature and humidity exposure is also an important requirement to be fulfilled by the TCOs to assure proper operation and durability. Besides improving current encapsulation methods, the corrosion resistance of the developed TCOs must also be enhanced to warrant the performance of optoelectronic devices. In this paper the performance of aluminum-doped zinc oxide (AZO) films deposited by pulsed dc magnetron sputtering has been studied. Structure, optical transmittance/reflectance, electrical properties (resistivity, carrier concentration and mobility) and corrosion resistance of the developed coatings have been analyzed as a function of the doping of the target and the coating thickness. Films grown from a 2.0 wt% Al2O3 target with a thickness of approximately 1μm showed a very low resistivity of 6.54 × 10-4 cm and a high optical transmittance in the visible range of 84%. Corrosion studies of the developed samples have shown very low corrosion currents (nanoamperes), very high corrosion resistances (in the order of 107 ) and very high electrochemical stability, indicating no tendency for electrochemical corrosion degradation., The authors acknowledge financial support from the European Commission obtained in the IN-LIGHT project (7th Framework Programme, FP7; Grant agreement nr.: 314233) and the ERC 2008 Advanced Grant (INVISIBLE n°. 228144), as well as the from the Spanish Ministry of Science and Innovation obtained in the project CSD2008-00023 FUNCOAT (in frames of the CONSOLIDER INGENIO-2010 program) and the Portuguese Science Foundation (FCT-MEC) through the projects EXCL/CTM-NAN/0201/2012 and PEst-C/CTM/LA0025/2013-14.

The aim of this study was to verify the possible physical and chemical changes that may occur on the surface of Ag–TiCN coatings after exposure to the culture media used in microbiological and cytotoxic assays, respectively tryptic soy broth (TSB) and Dulbecco's modified eagle's medium (DMEM). After sample immersion for 24 h in the media, analyses were performed by glow discharge optical emission spectroscopy discharge radiation (GDOES), Rutherford backscattering spectroscopy (RBS) and x-ray photoelectron spectroscopy (XPS). The results of GDOES profile, RBS and XPS spectra, of samples immersed in TSB, demonstrated the formation of a thin layer of carbon, oxygen and nitrogen that could be due to the presence of proteins in TSB. After 24 h of immersion in DMEM, the results showed the formation of a thin layer of calcium phosphates on the surface, since the coatings displayed a highly oxidized surface in which calcium and phosphorus were detected. All these results suggested that the formation of a layer on the coating surface prevented the release of silver ions in concentrations that allow antibacterial activity., IC acknowledges the financial support of FCT-Fundacao para a Ciencia e a Tecnologia through the grant SFRH/BD/67022/2009. REG acknowledges support from Ramon y Cajal programme (RyC2007-0026). This research is sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade and by national funds through FCT-Fundacao para a Ciencia e a Tecnologia in the framework of the Strategic Projects PESTC/FIS/UI607/2011, PEST-C/EME/UI0285/2011, PTDC/CTM/102853/2008.The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the Project 'BioHealth-Biotechnology and Bioengineering approaches to improve health quality', Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. The authors also thank the project 'Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB', Ref. FCOMP-01-0124-FEDER-027462.

For many high-temperature applications, coatings are applied in order to protect structural materials against a wide range of different environments: oxidation, metal dusting, sulphidation, molten salts, steam, etc. The resistance achieved by the use of different kind of coatings, such as functionally graded material coatings, has been optimized with the latest designs. In the case of supercritical steam turbines, many attempts have been made in terms of micro-structural coatings design, mainly based on aluminides, and other diffusion coating systems in order to consider alternatives, nano-structured coatings based on Cr and Al compositions and deposited by a physical vapor deposition technique, were assessed to high-temperature oxidation resistance in steam environments. The oxidation kinetics where analyzed for up to 2,000 h at 650 °C by means of gravimetric measurements. The evaporation behavior was also analyzed by thermogravimetric-mass spectrometry. Excellent results where observed for some of the nano-structured coatings tested. Those results where compared to results obtained for micro-structured coatings. Based on that comparison, it was deduced that the nano-structured coatings have a potential application as protective systems in high-temperature steam environments.

Considering it is somewhat difficult to crystallize thermochromic nickelates through a soft process, a major challenge in NdNiO3 crystallization is the stabilization of the Ni3+ oxidation state against Ni2+. The aim of the present work was to understand why a soft annealing is sufficient while an oxygen high pressure (200 bar) is usually considered as required. Thin films of 300 nm have been deposited by reactive magnetron sputtering at room temperature and working pressure of 0.5, 4, and 7 Pa. The oxygen content of as-deposited and annealed films was estimated by Rutherford backscattering spectrometry, whereas the nickel oxidation state evolution was followed by X-ray photoelectron spectroscopy. The measurements showed that the Ni3+ state is reached after deposition whatever the deposition pressure but that an oxygen loss occurs during air annealing with a magnitude depending on the deposition pressure. X-ray diffraction measurements, four-point probe electrical measurements, and infrared optical properties vs temperature were consistent with these results. Thin films deposited at 0.5 Pa and annealed in air at 820 K lead to an orthorhombic structure which becomes rhombohedral when the deposition pressure reaches 7 Pa. The oxygen loss causes a deterioration of the electrical resistivity, which was also evidenced by the thermochromic behavior measured using Fourier transform infrared spectroscopy. © 2014 American Chemical Society.

A complete experimental study of temperature dependence of the total spectral emissivity has been performed, for the first time, for absorber-reflector selective coatings used in concentrated solar power (CSP) systems for energy harvesting. The coating consist of double cermet layers of silicon oxide with different amounts of molybdenum over a silver infrared mirror layer. The experimental measurements were carried out by a high accurate radiometer (HAIRL) with controlled atmosphere in the mid-infrared and for temperatures between 150 and 600 C. The spectral emissivity is nearly constant in this temperature range. Therefore, the temperature dependence of the total emissivity is given by Planck function. These results were compared with those obtained with the usual calculus using room temperature reflectance spectrum. Finally, the performance of the coating was analyzed by comparison of coated respect to non-coated stainless steel., This work was financially supported by the European Commission (project HITECO FP7-ENERGY-2010-1Collaborative N. 256830) the Spanish Ministry of Science and Innovation (projects FUNCOAT CSD2008-00023, RyC2007-0026) and program ETORTEK of the Consejería de Industria of the Gobierno Vasco in collaboration with the CIC-Energigune Research Center. L. González-Fernández acknowledges the Basque Government the support through a Ph.D. fellowship.

New multifunctional materials based on well-established materials to which functional properties are added, such as antibacterial performance, have become a relevant research topic, in order to meet the requirements of today's technological advances. This paper reports the results of a detailed structural and chemical characterization study of ZrCN-Ag coatings produced by reactive magnetron sputtering, as well as the release of silver after immersion in a simulated body fluid (Hank's balanced salt solution), which mimic the material behaviour within the human body. The chemical composition was evaluated by electron probe microanalysis, x-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy, whereas the structure was assessed by Raman spectroscopy and x-ray diffraction. The material exhibits a homogeneous distribution of the elements throughout the films, with a (C + N)/Zr ratio of around 1.3 and 15 at% of silver. A mixture of amorphous (a-C and CNx) and crystalline phases (ZrCN) was identified. In addition, the silver was detected to be released in less than 0.7% of the total silver in the films, occurring during the first two hours of immersion; no further release was evidenced after this period of time. © 2013 IOP Publishing Ltd., This research is partially sponsored by FEDER funds through the program COMPETE—Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundaçâo para a Ciência e a Tecnologia, under the projects ANTIMICROBCOAT—PTDC/CTM/102853/2008. This work has also been supported by the Ministerio de Ciencia e Innovación of Spain through the Consolider-Ingenio 2010 programme (CSD2008-00023) and through project RyC2007-0026.

Cr–O–Al thin film mixed oxides grown on Si (100) substrates by reactive magnetron sputtering using different target compositions from 90% Cr (10% Al) to 10% Cr (90% Al) and oxygen fluxes in the range from 0 to 15 sccm have been investigated using ex situ XPS, XPS depth profiles and ARXPS. The chemical information obtained with XPS as well as the observed chemical shift of the Cr 2p, Al 2s and O 1s bands points to the formation of mixed substitutional Me2O3 oxides (Me = Al + Cr) instead of the formation of single oxide phases. Compositions and stoichiometries obtained from concentration depth profile measurements (CDP) simultaneously using XPS and Ar+ bombardment confirm the formation of such a type of substitutional mixed oxides. ARXPS allows ruling out oxygen preferential sputtering during Ar+ bombardment. Finally, it is shown that the optical properties of the films like their refractive index can be controlled through their chemical composition. Ministerio de Ciencia e Innovación CSD2008- 00023 (Consolider-Ingenio 2010) Ministerio de Ciencia e Innovación MAT2008-06618-C02

Low-emissivity (low-e) coatings on glass are nowadays extensively used for energy saving applications in architectural windows and on solar thermal collectors. In this work the feasibility of TiN-based layers as low-e coatings has been studied. TiN samples were deposited by reactive magnetron sputtering and, in order to improve their optical properties (transmission in the visible range, T and emissivity, ε), we have investigated the changes in optical response following three different approaches: (i) post-deposition annealing treatments up to 500 ◦C, (ii) doping the TiN layers with aluminium (target composition: Ti/Al = 90/10, 75/25 and 50/50) and (iii) deposition of antireflective coatings of TiO2 in multilayers structures. The crystalline structure and chemical composition of the multilayers were studied by X-Ray Diffraction and Rutherford Backscattering Spectroscopy, respectively. Spectroscopic Ellipsometry, Fourier Transform Infrared Spectroscopy and direct emissivity measurements were employed to determine the optical properties T and ε. We have concluded that the most noticeable improvement has been obtained by the deposition of multilayers structures increasing in a 30% the original transmittance of the single TiN coatings., Spanish Ministry of Science and Innovation, MCINN

Ag–TiCN coatings were deposited by dc reactive magnetron sputtering and their structural and morphological properties were evaluated. Compositional analysis showed the existence of Ag–TiCN coatings with different Ag/Ti atomic ratios (ranging from 0 to 1.49). The structural and morphological properties are well correlated with the evolution of Ag/Ti atomic ratio. For the samples with low Ag/Ti atomic ratio (below 0.20) the coatings crystallize in a B1-NaCl crystal structure typical of TiC0.3N0.7. The increase in Ag/Ti atomic ratio promoted the formation of Ag crystalline phases as well as amorphous CNx phases detected in both x-ray photoelectron spectroscopy and Raman spectroscopy analysis. Simultaneously to the formation of Ag crystalline phases and amorphous carbon-based phases, a decrease in TiC0.3N0.7 grain size was observed as well as the densification of coatings., Spanish Ministry of Science and Innovation, Fundação para a Ciência e Tecnologia (FCT), CRUP Institution, MCINN

Transparent Al-doped ZnO thin films were deposited by reactive magnetron sputtering with different oxygen flow rates. The electronic resistivity, measured by the 4 point-probe method, is very sensitive to the sample position relative to the magnetron axis: the closer the magnetron from the axis the higher the resistivity. This is more pronounced for the films deposited under higher oxygen flow rate. Neither Rutherford backscattering spectroscopy nor Zn–K edge X-ray absorption near-edge structure (XANES) analyses evidenced any change in chemical composition such as a measurable variation of the oxygen stoichiometry. XANES at the Al–K and O–K edges show that (i) a portion of the aluminum atoms get positioned in octahedral conformation with oxygen, consistent with the formation of an Al2O3(ZnO)m nanolaminate structure, (ii) the films exhibit relaxed O-terminated (0 0 0 1) surfaces with a higher density of empty states in more resistive samples. These two findings are believed to play a significant role on the electrical measurements by dopant deactivation and by creating an insulating barrier at the film surface, respectively. Ministerio de Ciencia e Innovación CSD2008-00023 Ministerio de Ciencia e Innovación FIS2009-12964-C05-04

Ti–Si–C–ON films were deposited by DC reactive magnetron sputtering and their chemical properties, biofilm formation and toxicity were characterized. Based on the films composition three different growth regimes were identified on the films; (I) N/Ti = 2.11 (high atomic ratio) and low oxygen content; (II) 0.77 ≤ N/Ti ≤ 1.86 (intermediate atomic ratio) and (III) N/Ti ≤ 0.12 (low ratio) and high oxygen content. The phase composition varied from mainly TiN on regime I to TiCN on regime 2 and titanium oxides on regime III. Taking into account the results of biological characterization (biofilm formation and cytotoxicity), it was possible to conclude that samples with a high TiN content (regime I) presented more favorable biocompatibility, since it was less prone to microbial colonization and also displayed a low cytotoxicity., The authors are grateful to Dr. Alicia Andres, Institut de Ciencia de Materiales de Madrid (ICMM-CSIC), for his assistance in carrying out the Raman spectroscopic analysis. The work was financially supported by the CRUP Institution (project "Accao No E-1007/08), and the Spanish Ministry of Science and Innovation (projects FUN-COAT CSD2008-00023, MAT2008-06618-C02 and Integrated action HP016-2007). This research is partially sponsored by FEDER funds through the program COMPETE- Programa Operacional Factores de Competitividade and by Portuguese national funds through FCT-Fundacao para a Ciencia e a Tecnologia, under the project PTDC/CTM/102853/2008.

The polymers Epoxy and Poly(Methyl MethAcrylate) spin coated on Interstitial Free (IF) steel were subjected to external stresses and studied using the Delft Variable Energy Positron (VEP) beam facility. The polymer/metal interface was identified using an S-W map. After tensile experiments vacancy formation in the steel substrate was measured but no significant changes at the interface were observed. Positronium formation in the polymer layer was determined to be 30%. Results of application of the above method to a multilayer coating on an industrial can are presented.

Positron annihilation studies on SiO2 structures show that a significant fraction of the positrons forms positronium (Ps). The fraction of Ps is obtained by lifetime measurements and 2D-ACAR experiments, as well as by decomposition of Doppler broadening (DB) spectra. The narrowest component is attributed to para-positronium (p-Ps). For all SiO2 structures studied the DB parameters S and W show similar values. Dramatic changes are observed when point defects are introduced by ion implantation. These defects are very efficient traps for positrons. Once positrons are trapped at the defects the Ps formation reduces to zero. In addition the S parameters drops by about 10%, while the W parameter increases by about 20%. Vacuum annealing experiments show that the original conditions are restored after treatments at about 800 K. For the first time we explain the transport of positrons in biased SiO2 in terms of Ps production and suppression.

ZrCN coatings were deposited by dc reactive magnetron sputtering with N2 flows ranging from 2 to 10 sccm in order to investigate the influence of the nitrogen incorporation on structure and properties. Information about the chemical composition was obtained by glow discharge optical emission spectroscopy and Rutherford backscattering spectroscopy. The evolution of the crystal structure studied by X-ray diffraction revealed the formation of a face-centred cubic ZrCN phase for N2 flows greater than 4 sccm. Additionally, the presence of an amorphous phase in the coatings deposited with the highest N2 flows could be evidenced by Raman spectroscopy and X-ray photoelectron spectroscopy. This phase can act as a lubricant resulting in a low coefficient of friction as shown in the conducted ball-on-disc tests. Nanoindentation measurements showed that coatings deposited with a 6 sccm N2 flow had the maximum hardness which also revealed the best performance in the conducted dry cutting tests., CRUP Institution, Spanish Ministry of Science and Innovation, Christian Doppler Research Association

Silver-containing diamond-like-carbon (DLC) is a promising material for biomedical implants due to its excellent combination of antibacterial and mechanical properties. In this work, a dual-cathode pulsed filtered cathodic arc source containing silver and graphite rods was employed in order to obtain DLC samples with various silver contents. Chemical composition of the samples was analyzed by acquiring their compositional depth-profiles using radio-frequency Glow Discharge Optical Emission Spectroscopy (rf-GDOES), while the microstructural properties were analyzed by X-ray diffraction and Raman spectroscopy. Tribological studies carried out against UHMWPE balls in fetal bovine serum indicate that the presence of silver in DLC could be beneficial to reduce the wear of the polymeric surfaces. Ministerio de Ciencia e Innovación CSD 2008-0023 (FUNCOAT) Ministerio de Ciencia e Innovación FIS2009-12964-C05-04

The use of a 50-nm thick Mo interlayer on silicon substrates for the nucleation enhancement of microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films synthesized by hot filament chemical vapour deposition was studied. The MCD and NCD films were deposited using methane concentrations of 1% and 2%, respectively. The presence of a Mo nucleation layer enabled the formation of more uniform NCD films with reduced surface roughness (rms roughness approximately 40 nm for a 750-nm thick layer) and with significantly less interfacial voids due to the superior nucleation densities and surface coverage in the early stages of NCD film formation. During the initial stages of MCD film growth, the nucleation density increased by one order of magnitude as compared to uncoated silicon. As a result, much thinner MCD films with smaller surface grain sizes and, thus, reduced surface roughness could be produced as well. The presence of a Mo nucleation layer not only leads to a structural optimization of NCD and MCD films but also allows fast nucleation and film growth kinetics at relatively low substrate temperatures (approximately 575 degrees C), relevant for the coating of substrate materials that do not withstand high substrate temperatures.