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Two nickel-based coatings obtained from electroless plating baths are studied. The first one is studied as-deposited whereas the second one was subjected to a heat-treatment. Hardness and Young's modulus of coatings have been investigated by means of indentation tests. Results show that mechanical properties are homogenous in the whole thickness of the coating. On the other hand, the heat treatment leads on a significantly increase of hardness and modulus. Residual stresses in the coatings are studied by the incremental ring core method. Values of residual stresses are small, scattered and do not seem to be heat-treatment dependent. Without any modifications of residual stresses before and after heat treatment, mechanical properties evolutions were attributed to the microstructural modification of the coating and to the precipitation of hard phases.

A discussion on the genocide of Srebrenica and the aftermath of the events

To withstand oxidation at a temperature >= 850 °C, an optimized Ti1-xAlxN coating was grown via reactive High Power Impulse Magnetron Sputtering (HiPIMS) technology on three identical Ti0.48Al0.48Cr0.02Nb0.02 billets. Different substrate surface pre-treatments were designed to increase performance: i) mechanical polishing, ii) mechanical polishing combined with a strong plasma etching, and iii) mechanical polishing coupled to both a weak plasma etching and a Ti1-yAly metallic interlayer deposition. Then, all the specimens were cyclically heat treated up to 200 cycles at 950 °C, using a Burner Rig (BR) facility. The chosen Ti1-xAlxN/substrate interface architecture considerably influenced average compressive residual stress (Sres) and adhesion of just deposited films. Moreover, it was possible to identify a clear relationship between Sres behavior and each coating comportment after BR tests. It became clear that the weak plasma etching/Ti1-yAly interlayer match helped improving the system stability (i.e. very low average residual stress thermal relaxation) thus guarantying high temperature oxidation resistance.[object Object]

The need for materials with special and often unique functionalities is particularly felt in forefront domains, particularly in areas where materials are subjected to extreme erosion and/or corrosion. Coating technologies are becoming more widespread since they help to improve existing materials and products separating the structural performances from the surface-protection performances [1]. Refractory metals and their alloys constitute a class of particularly interesting materials because, thanks to their outstanding properties, they can be used in hazardous environments and extreme conditions. In this work, we present an investigation on W and Ta based coatings on stainless steel substrates. Among many different applications, tungsten is used in electronic industry for x-ray optics and in harsh environments such as thermonuclear fusion reactors (tokamaks) where it is generally considered to be the most promising plasma facing material (PFM). This is due to its high cohesive energy, which makes it resistant to erosion and ensures an high sputtering threshold under hydrogen bombardment, its high melting point (the highest one when considering refractory metals), low coefficient of thermal expansion, good electrical conductivity, low affinity with hydrogen and excellent thermal conductivity. Unfortunately tungsten finds just a few applications in the standard industrial fields because of the low stability of its oxides (WO3, WO2). Tantalum has properties that make it useful for many applications, from electronics to mechanical and chemical systems. Its high melting point, toughness, low ductile-to-brittle transition temperature and exceptional resistance to chemical attack make it an attractive coating material for components exposed to high temperature, wear, and harsh chemical environments. Its excellent resistance against corrosion is ensured by the formation of a stable passive oxide film (Ta2O5). Tantalum is also used to produce a variety of alloys that have high melting points, are strong and have good ductility. In particular W is alloyed with Ta to lower brittle-to-ductile transition temperature [2,3]. W rich alloys (W-Ta) are not very well known and, to the authors' knowledge, there are just a few papers in literature. On the contrary Ta rich alloys (Ta-W) are well known materials and they excel due to their good mechanical properties and excellent corrosion resistance. With the 10 % of W the resulting alloy is 1.4 times stronger than pure tantalum but it remains easy to work even at high temperature (up to 1 600 °C). Physical vapor deposition (PVD) is one of the most promising coating technology and it is widely employed to improve mechanical, wear and corrosion properties of materials. Moreover it is possible to tailor coating features (crystallinity, grain orientation, etc.) to obtain properties that can be far apart from the bulk material ones. In this work, different films, with different W and Ta contents, have been produced via PVD using Direct Current Magnetron Sputtering (DCMS) and Pulsed Laser Deposition (PLD) [4]. Moreover pure W and Ta samples have been deposited by High-Power Impulse Magnetron Sputtering (HiPIMS) [5,6]. For these samples the various deposition parameters have not been fully optimized. However, the preliminary results look very promising. DC Magnetron Sputtering is a traditional PVD technique extensively used in industry. PLD is a relatively new technique that permits to deposit films with very complex stoichiometry (e.g. YBCO). Moreover it is able to deposit nanostructured materials tailoring film features at the nanoscale. HiPIMS is an innovative technique which utilizes magnetron sputtering cathodes and high peak power density of up to 3 kW cm-2 on the target. The plasma produces a particle flux with high degree of ionization. HiPIMS has been successfully used to enhance coating adhesion. It produces high-density microstructure films with smooth surfaces. Moreover, it has a few industrial applications in hard, electronic, and optical coatings. The produced refractory metal based coatings have been extensively analyzed. Microstructural characterization activities consisted of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The nano-mechanical properties of the films (hardness and elastic modulus) have been analyzed by nanoindentation testing. Adhesion has been finally evaluated by scratch tests [7], using a fully-computerized UMT apparatus. The electrochemical properties of thin films have been also evaluated in 3.5 wt.% NaCl aqueous solution [8]. The goal of this work was to evaluate the properties of high tech nanostructured coatings of refractory metals. Moreover it was possible to stress how to drive the film characteristics needed for the specific application using three different techniques.

Superaustenitic stainless steels have become of growing interest in industrial and technological fields, but there is not a complete understanding on their fundamental properties and their performances. For this paper, AISI 904-L superaustenitic samples were nitrided and carburized in order to study the expanded austenite stability under severe deuterium and helium ion bombardment. Surface treatments were conducted using pulsed plasma glow discharges in a low pressure atmosphere, and a dense plasma focus device was used to irradiate the samples. Characterization techniques used were focused ion beam/SEM, energy-dispersive X-ray spectroscopy, and grazing incidence X-ray diffraction. Our results showed in carburized samples lattice expansion growth with the time treatment, but in nitrided samples, an expanded austenite reduction with time treatment was observed due to the formation of nitride nanoagglomerates. Moreover, this ion impingement provoked surface melting and a severe collision cascade, and a damaged bead located under the craters composed solely of minor alloying atoms. Furthermore, nitrided samples were more stable following ion bombardment than the carburized ones. When helium ions were used, the loss of expansion (triggered by diffusion processes of N or C to deeper regions) was more pronounced in the expanded austenite, but when deuterium ions were used to bombard the sample, there was a crystallite development of stressed austenite, which provoked a diffraction peak arousal at 43.3°. Fil: García Molleja, Javier. Universite de Nantes; Francia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina Fil: Milanese, Maria Magdalena. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gomez, Bernardo Jose Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina Fil: Moroso, Roberto Luis. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Piccoli, M.. Università di Roma; Italia Fil: Niedbalski, Jorge Julio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Fisica Arroyo Seco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Burgi, Juan Mauel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina Fil: Bemporad, E.. Università di Roma; Italia Fil: Feugeas, Jorge Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina

AlTiN is a promising anti-oxidation and corrosion protective material. Thanks to the formation of a coherent, compact and adherent alumina scale, it can be applied in harsh environments. In this work, the intrinsic properties of AlTiN films produced by reactive High Power Impulse Magnetron Sputtering (HiPIMS) have been investigated. Different substrates were chosen considering their technological interest: a common stainless steel (AISI 304), the T91 martensitic steel, which is conventionally used for nuclear fusion and fission plants, and, finally, a light alloy for aeronautic applications (g-TiAl), which represents a possibility to replace Ni based super-alloy in aircraft turbine engines. Working gas composition has been systematically changed (N2/(Ar+N2) atomic ratio 10, 25, 50 ,75, 100 %). Morphology, microstructure, hardness, elastic modulus, residual stress have been studied through high resolution methodologies. Microstructural analyses were carried out by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Moreover, films nano-mechanical properties, as hardness (H) and Young's modulus (E), were estimated by nano-indentation tester, while adhesion was evaluated by scratch tests. In order to investigate the average residual stress in the produced coatings, a recently proposed approach was used, which involves an incremental FIB milling of annular trenches at material surface, combined with high resolution SEM imaging . Finally, AlTiN/T91 coatings were subjected to long duration tests for the evaluation of corrosion by molten metal (Pd or Pb-Bi alloy), while all the other films were tested in air at high temperature, to investigate the behaviors of AlTiN films subjected to thermal cycles. SEM and XRD results showed a significant modification of films' microstructure due to selected deposition parameters: it ranges from quasi-amorphous structure at high N2 percentage to crystalline one at low nitrogen content. This means that the energy flux carried to the substrate considerably changes. Mechanical properties were found to be extremely promising: measured hardness reached 40 GPa. Moreover, by optimizing N2 percentage during the deposition process, it is possible to maximize the H/E ratio, which provides an indicator of the coating's elastic strain at failure. Finally, it was found how microstructure and/or mechanical properties of the coatings help to foresee the film/substrate system adhesion. The possibility to choose different experimental conditions coupled with an extensive characterization of the deposited coatings, allows to obtain useful information about structure/properties correlations and then, to optimize deposition parameters to achieve the required characteristics for specific applications.

A TiO2 (anatase) nanopowder suspension was processed by High Velocity Suspension Flame Spraying (HVSFS). The resulting coatings were characterized and compared to conventional atmospheric plasma sprayed (APS) and HVOFsprayed ones. The HVSFS operating parameters can be adjusted in order to achieve dense coatings, with a fine (nearnanosized) structure and a homogeneous distribution of anatase and rutile: these coatings have lower pore interconnectivity and higher wear resistance than APS and HVOF ones. Alternatively, quite large unmelted agglomerates of anatase nanoparticles can be embedded in the coating, increasing the porosity and the anatase content for enhanced photocatalytic efficiency.

Recently introduced FIB/SEM analysis in microscopy seems to provide a high-resolution characterization of the samples by 3D (FIB) cross-sectioning and (SEM) high resolution imaging. The aim of this study was to apply the FIB/SEM and SEM/EDS analysis to the interfaces of a metal-ceramic vs. two zirconia-ceramic systems. Plate samples of three different prosthetic systems were prepared in the dental lab following the manufacturers' instructions, where metal-ceramic was the result of a ceramic veneering (porcelain-fused-to-metal) and the two zirconia-ceramic systems were produced by the dedicated CAD-CAM procedures of the zirconia cores (both with final sintering) and then veneered by layered or heat pressed ceramics. In a FIB/SEM equipment (also called DualBeam), a thin layer of platinum (1 μm) was deposited on samples surface crossing the interfaces, in order to protect them during milling. Then, increasingly deeper trenches were milled by a focused ion beam, first using a relatively higher and later using a lower ion current (from 9 nA to 0.28 nA, 30KV). Finally, FEG-SEM (5KV) micrographs (1000-50,000X) were acquired. In a SEM the analysis of the morphology and internal microstructure was performed by 13KV secondary and backscattered electrons signals (in all the samples). The compositional maps were then performed by EDS probe only in the metal-ceramic system (20kV). Despite the presence of many voids in all the ceramic layers, it was possible to identify: (1) the grain structures of the metallic and zirconia substrates, (2) the thin oxide layer at the metal-ceramic interface and its interactions with the first ceramic layer (wash technique), (3) the roughness of the two different zirconia cores and their interactions with the ceramic interface, where the presence of zirconia grains in the ceramic layer was reported in two system possibly due to sandblasting before ceramic firing.

This study describes the investigations of failure in an e-type clip at the inside of rear arch, where the stresses are maximum owing to in-service loading and bending that occurs during forming operations. Visual inspection, stereomicroscopy, optical-microscopy and Scanning Electron Microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) have been used as the characterization techniques. The microstructural, morphological changes were compared both in the central area and close to the location of failure in e-clip. During primary heating for forming steel rod into e-clip shape, the oxidation and decarburization occurs which caused the formation and penetration of iron oxide. The average thickness of oxide layer was found to be 20 µm with localized areas, where the oxides penetrated up to depth of 50 µm. During forming and shot peening operations, the iron oxide ingested in material at the inside circumferential region of rear arch, which triggered the initiation and propagation of fatigue phenomenon in service. The SEM-EDS analysis and fractography confirmed the presence of iron oxide and pearlite lamellar tearing at the crack initiation site, respectively. It is suggested to use electric induction heating for forming of steel rod into e-clip shape or increased the silicon content from two to three weight percent, which minimize the thickness of oxide layer. The finishing process by adding air spray or tapping of the rod after heating will further help to remove the scale at the critical region before taking it up for mechanical forming operations.

In this work, the ternary titanium, copper, and silver (Ti-Cu-Ag) system is investigated as a potential candidate for the production of mechanically robust biomedical thin films. The coatings are produced by physical vapor deposition—magnetron sputtering (MS-PVD). The composite thin films are deposited on a silicon (100) substrate. The ratio between Ti and Cu was approximately kept one, with the variation of the Ag content between 10 and 35 at.%, while the power on the targets is changed during each deposition to get the desired Ag content. Thin film characterization is performed by X-ray diffraction (XRD), nanoindentation (modulus and hardness), to quantitatively evaluate the scratch adhesion, and atomic force microscopy to determine the surface topography. The residual stresses are measured by focused ion beam and digital image correlation method (FIB-DIC). The produced Ti-Cu-Ag thin films appear to be smooth, uniformly thick, and exhibit amorphous structure for the Ag contents lower than 25 at.%, with a transition to partially crystalline structure for higher Ag concentrations. The Ti-Cu control film shows higher values of 124.5 GPa and 7.85 GPa for modulus and hardness, respectively. There is a clear trend of continuous decrease in the modulus and hardness with the increase of Ag content, as lowest value of 105.5 GPa and 6 GPa for 35 at.% Ag containing thin films. In particular, a transition from the compressive (−36.5 MPa) to tensile residual stresses between 229 MPa and 288 MPa are observed with an increasing Ag content. The obtained results suggest that the Ag concentration should not exceed 25 at.%, in order to avoid an excessive reduction of the modulus and hardness with maintaining (at the same time) the potential for an increase of the antibacterial properties. In summary, Ti-Cu-Ag thin films shows characteristic mechanical properties that can be used to improve the properties of biomedical implants such as Ti-alloys and stainless steel.

Nanometrology refers to measurement techniques that assess materials properties at the nanoscale. Laboratory-based characterisation of nanomaterials has been the key enabler in the growth of nanotechnology and nano-enabled products. Due to the small size involved, dimensional measurements has dominated such characterisation underpinned by a tremendous development in stand-alone electron/ion microscopes and scanning probe microscopes.However, the scope of nanometrology extends far beyond off-site, laboratory-based measurements of dimensions only, and is expected to have a tremendous impact on design of nano-enabled materials and devices.In this article, we discuss some of the available techniques for laboratory-based characterisation of mechanical and interfacial properties for nanometrology. We also provide a deep insight into the emerging techniques in measuring these properties, keeping in view the need in advanced manufacturing and nanobio-interactions to develop multifunctional instrumentation, traceable and standardized methods, and modelling tools for unambiguous data interpretation.We also discuss the evaluation of nanomechanical properties and surface/interface response of materials, within the purview of manufacturing processes and standardization.Finally, we discuss scientific and technological challenges that are required to move towards real-time nano-characterisation for rapid, reliable, repeatable and predictive metrology to underpin upscaling nanomaterials and nano-enabled products from the research field to industry and market. Keywords: Nanometrology, Nanoindentation, AFM, Bio, Microscopy, Nanoscopy

This article presents an experimental investigation to quantify the effects of high temperature exposure (400–600 °C) on the mechanical properties of single basalt fibres. To this purpose, a combination of single edge notch tension and nanoindentation micro-pillar splitting methods was used to provide an assessment of the fracture toughness of as-received and thermally treated basalt fibres. Similar values were obtained by the two different methods, and interestingly both highlighted an increase in K I c after heat treatment, up to 22% after exposure at 600 °C for 1h ( 1.59 ± 0.06 M P a m ). The increase in K I c suggests that microstructural changes occur in the fibres, as confirmed by high-speed nanoindentation mapping. Local radial heterogeneity in the fibre structure and elastic modulus and, possibly, the loss of defect orientation originally induced during the fibre drawing process are envisaged to control the decay of basalt fibres tensile strength during high temperature exposure, mimicking a thermal recycling process for composites.

This article reports the design, construction, and first use of an experimental device consisting of a specially designed vacuum chamber equipped with a reactive sputtering magnetron (RSM) to be used for controlled deposition of thin films on a Si(100) flat substrate. The setup was designed to allow for in situ and real-time recordings of X-ray diffraction patterns during the growth of the deposited films and was installed in the X-ray diffraction and spectroscopy beamline emerging from a superconducting wiggler source at the Brazilian Synchrotron Light Laboratory. The first use of the RSM setup was an in situ and real-time X-ray diffraction study of processes of growth of multilayered aluminum nitride thin films, whereas the operation parameters of the reactor were sequentially changed. This sequential process led to the development of multilayered films. Alternate variations in chamber pressure and magnetron power density allowed us to obtain thin films composed of several micrometer thick layers, with alternate amorphous and (10·0), (00·2), or (10·1) textured polycrystalline structures.

Residual stresses play a crucial role in determining material properties and behaviour, in terms of structural integrity under monotonic and cyclic loading, and for functional performance, in terms of capacitance, conductivity, band gap, and other characteristics. The methods for experimental residual stress analysis at the macro- and micro-scales are well established, but residual stress evaluation at the nanoscale faces major challenges, e.g. the need for sample sectioning to prepare thin lamellae, by its very nature introducing major modifications to the quantity being evaluated.Residual stress analysis by micro-ring core Focused Ion Beam milling directly at sample surface offers lateral resolution better than 1 μm, and encodes information about residual stress depth variation. We report a new method for residual stress depth profiling at the resolution better than 50 nm by the application of a mathematically straightforward and robust approach based on the concept of eigenstrain. The results are validated by direct comparison with measurements by nano-focus synchrotron X-ray diffraction. Keywords: FIB-DIC ring core, Residual stress, Eigenstrain, Depth profiling, Nano resolution, XRD

Ni-B coatings with low, increasing amount of Boron have been produced using a Ni sulfamate plating bath with the addition of dimethylaminborane. Coatings' characterization revealed that it is possible to produce crack-free coatings with a B content up to 0.12 wt%, with a thickness of about 40–50 μm. The introduction of an increasing amount of B changes progressively the coatings microstructure from columnar, to fine fibrous and then to lamellar. The presence of B as interstitial atom in the Ni elementary cell caused an increase of the residual stress, as measured by FIB-DIC method, which change from compressive to tensile as a function of B concentration. The microstructure refinement and the increase of the residual stresses caused a noticeable increase of the microhardness. On the other hand, the resistance to localized corrosion decreased by increasing the B content maybe due to the formation of micro-defects or micro-cracks on the Ni passive layer due to the residual stresses. To confirm this hypothesis, the Ni-B coatings have been annealed at 400 °C to achieve a complete stress relaxation. The stress relaxation caused a decrease of the hardness and a noticeable increase of the corrosion resistance.

Indentation tests have been carried out on a marble in order to define the role of the intra-grain microcracks on its mechanical behavior. The investigated marble shows a strong variability in grain-texture (granoblastic to xenoblastic) also on the scale of centimeter and contains different types of microdiscontinuities (cleavage cracks, grain boundaries cracks), despite the almost monomineralic composition of calcite crystals. The mechanical properties of the calcite grains have been determined by applying static non-instrumented Vickers and Knoop indentations and Berkovich nanoindentation in Continuous Stiffness Measurements (CSM) mode. The study has clearly revealed the influence of microcracks on the mechanical strength and deformability characteristics of the investigated rock, even on the smallest scales.