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Zirconium nitride thin films deposited by reactive magnetron sputtering recurrently present small amounts of hafnium (~1 at.%) in their composition derived from an inherent impurity existing in Zr targets. Hf presence in ZrN coatings is neglected by most of the researchers despite its known potential to modify properties of thin films. In this work, pure ZrN (0.9 at.% Hf contaminant) and ZrHfN thin films with intentional hafnium addition of 1.8, 3.7 and 5.5 at.% were deposited by reactive magnetron sputtering and characterized by RBS, GAXRD, SEM, nanohardness and high temperature oxidation tests. Based on the results, it is suggested that inherent hafnium presence in zirconium targets contributes for the good hardness values and oxidation resistance at 773 K registered for ZrN thin films.

TiN-WS x thin films with varying WS x content were co-deposited by reactive magnetron sputtering. GAXRD analyses showed that the addition of 4 at.% WS x led to loss of crystallinity of TiN phase and a complete amorphous characteristic was manifested upon incorporation of 19 at.% WS x . Nanohardness results indicated that TiN-WS x containing 4 and 19 at.% WS x presented 19.7 GPa and 18.4 GPa, respectively, following the rule of mixtures. Friction coefficient and wear rates measured in reciprocated tribological tests revealed that TiN-WS x coatings present an improved tribological performance when compared to pure TiN thin film at room temperature, registering friction coefficient of 0.42 ± 0.05 and 0.19 ± 0.03 for samples with 4 and 19 at.% WS x , respectively. Wear tests at high temperatures evidenced that sample with 4 at.% WS x did not provide advanced protection to substrate at 343 K and above due to deterioration. On the other hand, coating with 19 at.% WS x maintained low friction coefficient up to 343 K, registering an optimum wear rate of 0.86 × 10 −17 m 2 /N with no cracking occurrence.

Zr(1-x)Mo(x)N thin films were deposited by reactive magnetron sputtering with Mo content varying from 0 to 20 at.%. GAXRD revealed a gradual shrinkage of ZrN lattice constants as Mo concentration increased while no molybdenum crystalline phases were identified in ZrMoN coatings. XPS data showed a disturbance in ZrN electronic environment due to Mo presence, indicating a substitutional solid solution formation for samples up to 20 at.% Mo. Oxidation tests were carried out at 773 K, 873 K and 973 K for all thin films. ZrMoN samples did not maintain the original nitride structure when exposed to such high temperatures. On the other hand, Mo addition in ZrN matrix was favorable to the stabilization of the tetragonal zirconia (t-ZrO2) in preference to the more stable monoclinic zirconia (m-ZrO2) phase at high temperatures.

This study compares the corrosion resistance of ZrN and ZrSiN films deposited on AISI 430 steel by the magnetron sputtering technique. Corrosion resistance was evaluated using electrochemical imped...

Iso and non-iso architected TiN/Cr multilayers with constant composition were deposited by balanced magnetron sputtering aiming to investigate the influence of different architectures over coatings structures and properties. Glow discharge optical emission spectroscopy analyses were used to determine in-depth constituents and suggested that no diffusion of elements occurred between layers in room temperature. Field emission gun scanning electron microscopy analyses showed that all multilayers presented sharp interfaces and low porosity microstructures, with column-like grain growth influenced by layer sizes. Glancing angle X-ray diffraction analyses showed that multilayers consist of polycrystalline α-Cr and δ-TiN phases with a main peak in Cr(110) plane. The overlapping of TiN onto metallic layers led to the suppression of growth in the TiN(111) plane, although TiN layers thicker than 50 nm demonstrated a growth in plane TiN(200). Nanoindentation tests registered equal hardness values for all multilayers of around 16.2 GPa, on the other hand, a tendency to improve hardness has been identified for hierarchical multilayer. Oxidation tests revealed that architectures with thicker TiN top layers presented an improved oxidation resistance up to 600 oC, probably due to growth in more compact TiN(200) plane. However, TiN/Cr coatings did not resist integrally to oxidation tests at 750 oC.

Pure MoSx and MoSx + Hf thin films were deposited by magnetron sputtering and characterized by RBS, GAXRD, XPS, high temperature oxidation tests and tribological tests. Hf content was set at 12 at.% by RBS and GAXRD analyses revealed a complete amorphization caused by Hf incorporation. XPS analyses indicated that hafnium is inserted in MoSx in the form of HfSx, moreover, such compound was responsible for inhibiting the formation of MoS. These factors are closely correlated with improvements obtained in oxidation resistance, friction coefficient, wear rate and lifespan of MoSx thin films.

NbxAlyNz thin films were deposited by magnetron sputtering reactive technique with (y/x+y) ratio varying from 0 to 0.4, in order to maintain aluminum atoms inside NbN matrix in solid solution. GAXRD analyses revealed that the crystalline phase obtained for NbxAlyNz thin films was B1-NbN with a lattice constant shrinkage as Al concentration at these coatings was increased. Due to similarity in electro negativity values between Nb and Al, XPS analyses could not verify pronounced changes among as deposited NbxAlyNz coatings. The average hardness values evidenced that solid solution strengthening mechanism did not increase hardness significantly. The oxidation resistance increased with Al content and no oxide phases were registered by GAXRD analyses for coating with more aluminum added. However, SEM images revealed bubbles after oxidation at high temperatures for all samples.

A utilização de revestimentos é uma forma de melhorar as propriedades de um material. Os filmes ZrN e ZrSiN são conhecidos pelas suas boas propriedades mecânicas, porém existem poucas pesquisas que investiguem a resistência à corrosão dos mesmos. Dessa forma, por meio da técnica de Espectrometria de Impedância Eletroquímica, estudou-se a resistência à corrosão dos filmes de ZrN e ZrSiN depositados no aço inoxidável 316L imersos em uma solução de NaCl 3,0 % m/v, por um período de 1000 h. A técnica de nanodureza foi aplicada para avaliar a dureza. A morfologia dos filmes, antes e após o teste de imersão, foi analisada por Microscopia Eletrônica de Varredura. Observou-se que os filmes de ZrN e ZrSiN melhoraram as propriedades corrosivas do aço 316L. A adição de 2,5 % at. de Si ao filme ZrN melhorou a resistência à corrosão, mas não aumentou a dureza do recobrimento.

Biodiesel consists of long-chain fatty acid esters and it presents relatively inert behavior right after its production. However, structural changes occur during its storage, as this fuel has low oxidative stability, fact that increases its corrosivity. The problem of corrosion has become increasingly relevant due to the Government's policy of setting a gradual increase in the percentage of biodiesel added to diesel. The current study evaluated the effectiveness of three natural products to work as corrosion inhibitor in biodiesel. The evaluation was done by means of immersion tests and electrochemical impedance spectroscopy. Results showed that it is possible to reduce biodiesel influence on carbon steel corrosion and that it can be extend to other metals used in automotive engines.

NbN and Nb1-xAlxN thin films with various Al contents, with x ranging from 0.10 to 0.60, were deposited by magnetron sputtering of Nb and Al targets in an Ar/N2 atmosphere on 316L stainless steel and silicon substrates. The DC power applied to the Al target varied from 0 to 150 W, while the power at the Nb target was kept constant at 150 W. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Films with composition 0 ≤ x ≤ 0.40 presented the NbN-δ cubic phase, while for x = 0.60, the coatings showed the AlN-h hexagonal phase. All coatings showed columnar morphologies. Electrochemical corrosion resistance was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests, varying the exposure time to 3.5% (m/v) NaCl solution up to 30 days. The Al content was related to the systems corrosion response, being that films with higher levels of Al (x = 0.40 and 0.60) showed improved protective behavior against corrosion. The formation of a Nb2O5 and Al(OH)3 protective layer, as confirmed by Raman and XPS measurements, was related to increased corrosion resistance and reduced porosity in the coated systems after 30 days of immersion time in 3.5% (m/v) NaCl solution.

Screws are often used in total hip arthroplasty to increase the cementless acetabular metal-backed fixation stability. This study aimed at identifying metallurgical factors related to metal-backed screw fractures in two cases of premature total hip arthroplasty revision. A preliminary analysis of radiographs and retrieved parts was performed. Fractured screws were subjected to fracture analysis, energy dispersive X-ray spectroscopy (EDS) and metallographic analysis. A finite element analysis was performed to predict the stresses experienced by the screws. Two factors were identified: titanium alloy microstructure, consisting of alpha phase plates with oxygen-rich alpha case and as cast Cr–Co alloy with dendritic microstructure and unfavorably aligned shrinkage formation. Finite element analysis has showed enough level of stress to predict screw fracture in the case of unbounded metal-backed and bone interface.

This paper deals with the failure analysis of a potassium ore compactor roll that experienced short term fracture in service after a repair procedure. The journal bearing of the shaft experienced wear after a long period in use. Afterwards, a surface deposition was performed in order to retrieve the roll functionality, but it culminated in the formation of radial cracks beginning just near the shaft curvature radius. This portion of the roll was then removed and replaced with a new shaft interference-fitted and welded into the roll. Moreover, after this new repair procedure, the roll experienced a short term fracture. Failure analyses were performed by liquid penetrant, fracture analysis, hardness testing and metallographic analysis. Numerical simulations were also carried out considering the last repair features. Fatigue failure nucleated near a singularity at the shaft curvature radius. This singularity was originated from the interference fit and welding procedures.

A method is proposed in order to reduce significantly the influence of the coating shear stress and its cohesion failure on the normal adhesion stress of metallic films on polymers. Most methods used so far were not able to avoid the interference of the cohesion failure when the interface was delaminated in order to measure the adhesion strength. Our method has been proved to work and the results are more accurate than the standard pull-off method. The experiments consisted in delaminating copper films deposited by physical vapor deposition on four different kinds of polymeric substrates: polypropylene, polyamide 6, high impact polystyrene and polyethylene terephthalate. The polymer surfaces have also been modified by means of substrate sanding and flaming processes. Optical and scanning electron microscopies were used to study the morphology of both the removed copper film and the polymer surface after pulling-off. Adhesion work was measured by contact angle to determine the necessary energy to pull-off the metal–polymer interface.

Pedicle screws are widely used alternatives to improve the spine fusion in the treatment of several spine diseases. However, the screw fracture rates are still high nowadays. Efforts to provide design and material selection should be encouraged. This paper deals with the analysis of design issues related to failure event of 10 Ti6Al4V pedicle screws explanted from five patients who had rupture before 5 years in use. The objective of this study was to correlate the mechanical failure with the geometric and microstructural concerns. Bending fatigue was the main mechanism responsible for the failures. Fractures occurred near the thread end or at intermediate thread level. In some cases environmental assisted cracking (EAC) was associated with failure initiation. The formation of lamellar or platelike microstructure, the small thread root radius and surface roughness were factors related to failures.

The focus of this paper is to establish a characterisation method for seven polyamide (PA) grades to determine the major material to manufacture an automotive worm gear. The composite properties were measured according to the worm gear loadings: tensile strength, Young’s modulus, abrasion and impact resistance. They were also correlated to the PA moisture absorption and its glass fibre (GF) reinforcement. The data from mechanical tests were applied in the finite element analysis (FEA) using the von Mises stress criterion. Before the rig tests of the PA worm gears, the injection process was evaluated, through the capillary rheometry. A higher difficulty to process PA 6/6 30% GF was found, due to its lower apparent viscosity. In the end, the influence of moisture absorption was as decisive to the gear’s material selection as the GF to the pinion. Thus, the PAs with the best performance were: PA 6 with 30% GF (gear) and with PA 60% GF (pinion).

TiN-MoS 2 composite thin films deposited by dc magnetron sputtering with MoS 2 concentrations from 3 to 40 at.% were investigated. The elementary composition and the formed compounds were determined before and after wear. The crystalline structure of the composite thin films was accessed and the nature and concentration of the precipitates in the TiN matrix were imaged by transmission electron microscopy. The hardness and elastic moduli of the films were measured by nanoindentation and the elastic strain to failure calculated on the basis of these two magnitudes. The MoS 2 formed in the composite coatings during thin film co-deposition are nanoscopic in size, homogeneously distributed, and mostly amorphous, although part of them are crystalline. The present study does not confirm MoS 2 formation at grain boundaries or TiS formation by substitution of S for N in the TiN matrix. The hardness and elastic strain to failure are appreciably high for the present TiN-MoS 2 thin film composite coatings with MoS 2 concentrations up to 4%. The potential applications are discussed on the basis of these findings.

Non-isostructural Ti 0.7 Al 0.3 N(cubic B1)/Ti 0.3 Al 0.7 N(hexagonal B4) nanoscale multilayers were deposited by dc magnetron sputtering on steel substrates, with nominal periods of 6, 10, 20 and 40 nm. The structure, composition, periodicity, and interface abruptness of the samples were characterized by X-ray diffraction, glow discharge optical spectroscopy, medium energy ion scattering, and narrow resonant nuclear reaction profiling. The nanohardness and elastic modulus of the samples were determined, revealing superhardness of up to 57 GPa for the lowest nanoscale multilayer period. The H 3 / E 2 ratios were found to be superior to those of most metal nitride multilayers commonly used as protective coatings, which indicates a superior wear resistance for the present nanostructured coating. The results are discussed in terms of the present stage of understanding of nanoscale multilayer effects on the tribological properties of protective coatings.

Transport of N, O, and Ti during dc magnetron sputtering deposition of nanoscopic TiN/Ti and TiN structures on plasma nitrided M2 tool steel, as well as transport of metallic species composing the plasma nitrided steel substrates were investigated. N and O depth distributions were determined with subnanometric resolution using narrow resonant nuclear reaction profiling, whereas Ti was profiled, also with subnanometric depth resolution, by medium energy ion scattering. The surface elementary compositions of the TiN/Ti/nitrided steel and TiN/nitrided steel structures were determined by low energy ion scattering. The chemical compounds formed during deposition were accessed by X-ray photoelectron spectroscopy, indicating the presence of TiN, TiO2, Ti oxynitrides, as well as other metallic nitrides and oxynitrides, but no metallic Ti was observed. Owing to the observed intensive atom mobility, the compositions of the deposited films on plasma nitrided steel structures varied continuously on a nanoscopic scale, from the core of the steel substrate to the bulk of the stoichiometric TiN films. The Ti interlayer assists interdiffusion of all species, in contrast to the TiN film layer, which is known to be a diffusion barrier. The improved adhesion of TiN hard coatings to plasma nitrided steel under working conditions is discussed in terms of the gradual compositional change around the interfaces and the atomic mobility during their formation.

The stability against reaction with aluminum of materials and coatings commonly used in aluminum die casting was investigated. The materials considered here were H13 tool steel and Anviloy® 1150, whereas the coatings were TiN and CrN. Special model, freestanding, multilayered thin film structures were used in this study, in association with complementary differential scanning calorimetry and X-ray diffraction. The nature of the reactions (endo or exothermic) and their onset temperatures up to 1273 K were determined. Based on of these results, some activation energies for the different reactions taking place between aluminum and die material or between aluminum and coatings could be established. Different intermetallic compounds were formed in these reactions, which were identified by post mortem X-ray diffraction analysis. Anviloy® 1150 showed superior stability as compared to H13 tool steel, whereas CrN was more inert than TiN coatings. CrN exhibited the best performance among all materials and coatings considered here, although its practical application relies also on adhesion of the CrN coating to the die bulk material. The results are discussed on the lights of two recent models for soldering in aluminum die casting.

The susceptibility to reaction with solid and liquid aluminum of TiN and (Ti,Al)N coatings was investigated using complementary differential scanning calorimetry and X-ray diffraction. Special freestanding, multilayered thin film structures of aluminum and the testing coating material were prepared for the calorimetric analyses. The results indicate that increasing concentrations of Al in the (Ti,Al)N compound coatings shift the reactions between coating and aluminum towards higher temperatures, reducing significantly the heat of reaction and inhibiting Al–Ti intemetallic compound formation. Different effects determining the protective action of this kind of coating are discussed on the basis of the present findings, together with others from the literature. Aluminum-rich Ti 1 − x Al x N compound coatings, with x ranging from 0.6 to 0.7, are apparently inert (non-wettable) in the presence of aluminum up to 1000 °C, a temperature high enough to resist any known aluminum casting situation.

Zirconium silicon nitride (ZrSiN) thin films were deposited by reactive magnetron sputtering in order to verify the silicon influence on coating morphology and mechanical properties. The Si/(Zr+Si) ratio was adjusted between 0 to 15% just modifying the power applied on the silicon target. Only peaks associated to ZrN crystalline structure were observed in XRD analysis, since Si3N4 phase was amorphous. All samples have (111) preferred orientation, but there is a peak intensity reduction and a broadening increase for the sample with the highest Si/(Zr+Si) ratio (15%), demonstrating a considerable loss of crystallinity or grain size reduction (about 8 nm calculated by Scherrer). It was also observed that the I(200)/I(111) ratio increases with silicon addition. Chemical composition and thickness of the coatings were determined by RBS analysis. No significant changes in nanohardness with increasing Si content were found. The morphology observed by FEG-SEM presents non columnar characteristics for thin films with silicon addition. The set of results suggests that Si addition is restricting the columnar growth of ZrN thin films. This conclusion is justified by the fact that Si contributes to increase the ZrN grains nucleation during the sputtering process.

The adhesion improvement produced by bright plasma nitriding hardening of tool steel prior to TiN deposition was investigated by angle-resolved X-ray photoelectron spectroscopy and atomic profiling with sub-nanometric depth resolution. Steel hardening is considered to be a consequence of homogeneously distributed, very fine iron and chromium nitride precipitates existing in the N-diffused zone formed below the surface by bright plasma nitriding, a picture confirmed here by the chemical analysis of the near-surface regions of the steel substrate. Besides hardening, analysis of the O1s, N1s, Ti2p, Fe2p, and Cr2p photoelectron groups showed that the finely dispersed chromium and iron nitrides produced by plasma nitriding also replace in part the oxides and hydroxides in the near-surface regions. Ti profiling with medium energy ion scattering and N profiling with narrow resonant nuclear reaction pointed out the interdiffusion of at least these two species near the interfaces. Thus, the enhanced adhesion and improved performance observed in duplex treated tool steel are discussed in light of the present findings: i) stronger chemical bonding at the coating/substrate interface promoted by bright plasma nitriding of the steel substrate prior to TiN deposition and ii) enhanced interdiffusion around the coating/substrate interface owing to the removal of the oxides which constitute diffusion barriers, producing an enlarged contact area and more gradual coating/substrate interfaces.

Until now, thin films' deposition is the principal way to perform materials' surface finishing. Multilayers normally improve some of the original properties of a thin film. High corrosion resistance and high hardness values can be obtained with a particular multilayer wavelength. The high hardness presented by some multilayers may be attributed to the thin films' interfaces. The periodic interface structure can originate a great intrinsic stress, increasing the coating hardness. Nevertheless, adhesion problems may occur. The present work verifies the hardness of the multilayers and its relation with the use of ion beam mixing (IBM) to improve the adhesion of the coating with the substrate. The multilayers are deposited by magnetron sputtering and are composed of chromium and vanadium. The multilayers were characterized by several techniques like Rutherford backscattering (RBS) and microhardness. The multilayer coating present no contamination and high hardness values, even after the use of the IBM technique.

Bias voltage applied to the substrate holder during thin film deposition is frequently used for modifying the coating properties in magnetron sputtering process. In this work, TiN thin films were deposited on (1 1 1) silicon. The magnetron sputtering equipment used was coupled with a quadrupole residual gas analyzer (QMG) in order to analyze the argon to nitrogen ratio involved in the deposition process. The working pressure was always 3×10 −1 Pa, and the deposition time and source power were maintained constant for all samples. The bias voltage was varied in the range −100 V to +100 V. The deposited thin films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Rutherford backscattering spectroscopy (RBS) and microhardness. With these results we can observe the film structure differences among the samples.

Ti–6Al–4V alloys and their nitrides are of wide interest in technological applications because of their exceptional properties. The structure and composition of these alloys are strongly dependent on the deposition conditions. In this work, we report the influence of the ion energy on the film characteristics. We have used a dual ion beam sputtering (DIBS) equipment where the reactive ion (N 2 ) acceleration voltage was changed in the range of 200 to 400 V. The film structure was studied by means of an X-ray diffractometer (XRD) and the chemical composition and nitration degree were measured by X-ray photoelectron spectroscopy (XPS) and by a microprobe spectrometer. Coating hardness was checked using an ultramicrohardness tester equipped with a Vickers' indentor, and the corrosion resistance power was studied by means of cyclic voltammetry. The substrates used here were stainless steel ISO 316, the same used in most femoral prosthesis, and silicon monocrystals for the analytical tests. We compare the results of the coatings deposited by DIBS with films deposited by reactive magnetron sputtering.