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This study focuses on the effects of a surface mechanical attrition treatment on the structural and mechanical behavior of arc-sprayed Ni&ndash, Cr coatings deposited on steel substrates. The surface of the as-sprayed and SMATed coatings was characterized by X-ray diffraction, Scanning Electron Microscopy, and non-contact profilometry. The coating porosity was evaluated by using image analysis software. The residual stresses were determined using X-ray diffraction with the sin2&psi, Indentation tests were carried out on the cross sections of the different coatings to evaluate their hardness. The wear properties of the coatings were assessed using a pin-on-disk tester at ambient temperature without lubrication. The results showed that surface mechanical attrition treatment (SMAT) induced a grain refinement on the coating surface due to severe plastic deformation, which was associated with a significant improvement of the mechanical properties.

International audience; Research on the β-type titanium alloys containing non-toxic elements and non-allergic properties has increased rapidly during the past decade. The objective of our research work is to study the effect of copper on Ti-Nb-Ta-Zr (TNTZ) sputtered uniform/adhesive thin films. TNTZ-Cu thin films (1-2 µm) were DC magnetron co-sputtered from an alloying target Ti-23Nb-0.7Ta-2Zr (at.%) and a pure Cu target. These films contained amounts of copper varying from 4 to 18.6 at.%. An experimental study was carried out to characterize the physico-chemical properties of the samples’ surfaces by EDX, SEM, AFM, XRD and nanoindentation. The bactericidal activity of coatings was evaluated by inductively coupled plasma mass-spectrometry (ICPMS–MS). The films deposited were chemically homogenous and the columnar morphology of TNTZ-Cu films was due to the high deposition pressure in the magnetron chamber. The film roughness evaluated by atomic force spectroscopy (AFM) on the TNTZ-Cu 8.3 at.% Cu sample presented an RMS-value of 20.1 nm being the highest RMS of any Cu-sputtered TNTZ sample. These films with a copper content of 8.3 at.% showed the fastest bactericidal activity. The XRD spectrograms of TNTZ-Cu films showed that the films were single phased with the β-Ti BCC structure. The nanoindentation measurements showed that Young’s modulus (E) and hardness (H) of films varied respectively in the range 77–104 GPa and 3–6.4 GPa by increasing Cu content up to 18.6 at.%. E and H decreased to a copper content of ∼7%, and increased above. It seems that formation of an amorphous phase leads to increasing mechanical properties. The antibacterial performance of these innovative TNZT-Cu coatings suggests a potential application in hospitals, health care facilities, implants, schools and public places.

International audience; Super-elastic Titanium based thin films Ti-23Nb-0.7Ta-2Zr-(O) (TNTZ-O) (at.%) were deposited by direct current magnetron sputtering (DCMS) in Ar + O2 atmosphere. The effects of oxygen doping (TNTZ-O) on the microstructure, mechanical properties and biocompatibility of the as-deposited coatings were investigated. Nano-indentation measurements show that 1 sccm of reactive gas in the mixture is necessary to reach acceptable values of hardness and Young’s modulus. Mechanical properties are considered in relation to the films compactness, the compressive stress and the changes in the grain size. Data on Bacterial inactivation and biocompatibility are reported in this study. The biocompatibility tests showed that O-containing samples led to higher cells proliferation. The sputtered films showed bactericidal activity as followed by surface potential and pH changes within the disinfection process.

Superelastic thin films have a fairly wide field of applications. Thanks to their ability to accommodate a large deformation reversibly, superelastic films may be used as intermediate layers between the substrate and the hard layers. This significantly improves many properties such as adhesion, wear and coefficient of friction. They can also be used in the manufacture of medical devices such as stents. Although β-metastable titanium-based alloys have excellent properties, much of the published literature on the superelastic films is devoted to Ni-Ti. Thus, the purpose of this work is to develop new superelastic β-metastable titanium-based films, obtained by magnetron sputtering. After describing the experimental device used for the synthesis of thin films, we study more specifically the influence of deposition parameters on the properties of coatings. The morphology was characterized by the observation of fractured cross-sectional by scanning electron microscope. The X-ray diffraction was used to study the microstructure and texture of the deposited films. Finally, the superelastic effect was characterized by two methods, the spherical indentation and micro-pillars compression machined by focused ion beam; Les matériaux super-élastiques sous forme de couche minces présentent un domaine d’applications assez large. Grâce à leur aptitude à accommoder de grandes déformations de manière réversible, les films super-élastiques peuvent être utilisés comme sous couches entre le substrat et les revêtements dures. Cela permet d’améliorer significativement de nombreuses propriétés telles que : l’adhésion, le taux d’usure et le coefficient de frottement. Elles peuvent également être utilisées dans la fabrication des dispositifs médicaux tels que les stents. Bien que les alliages β-métastable à base de titane présentent des propriétés remarquables, une grande partie de la littérature publiée sur les films super-élastiques est consacrée aux alliages Ni-Ti. Ainsi, le but de ce travail est de développer de nouvelles couches super-élastiques de type β-métastable, obtenues par pulvérisation cathodique magnétron. Dans ce sens, deux types d’alliages ont été étudiés, les alliages binaires Ti-Nb et l’alliage quaternaire Ti-Nb-Ta-Zr. Après une description du dispositif expérimental utilisé pour la synthèse des couches, nous étudions plus particulièrement l’influence des paramètres de dépôt sur les propriétés des revêtements. La morphologie des revêtements a été caractérisée par microscope électronique à balayage. La diffraction de rayons X a été employée pour l’étude de la microstructure et la texture des films déposés. Enfin, l’effet super-élastique a été caractérisé par deux méthodes, l’indentation sphérique et la compression de micro-piliers usinés par faisceau d’ions focalisés

International audience

International audience