Multilayered and nanolayered hard nitride thin films deposited by cathodic arc evaporation. Part 1: Deposition, morphology and microstructure

TiN/AlTiN, TiN/CrN and CrN/AlTiN multilayer coatings have been deposited by the cathodic arc evaporation technique. The period is in the range 7-200 nm for a total thickness of 3 μm. The period's control of the nanoscaled hard films is achieved, a priori, by way of a simple geometrical calculation and, a posteriori, via both X-ray diffraction and transmission electron microscopy on cross-sections. Microstructure of the as-deposited coatings has been investigated by means of X-ray diffraction and transmission electron microscopy in connection with the decrease of the period λ. For lower periods (multilayered coatings), the fcc structures which derive from each nitride are observed while only the superlattice structure is found for nanoscale layered films (nanolayered coatings). Microstructure evolution with the period is investigated for the three systems and the differences are comment. Tribological behaviours and cutting performances are studied in [C. Ducros, F. Sanchette, submitted to Surf. Coat. Technol.]. © 2006

Influence of bias voltage on properties of AlCrN coatings prepared by cathodic arc deposition

International audienceAlCrN coatings were prepared by vacuum cathodic arc deposition. This low-temperature technique has been chosen due to its versatility, allowing the industrial up-scaling.In this study, the attention was focused on the correlation of the bias voltage with the resulting mechanical–tribological properties. For this purpose, the bias voltage was varied from 0 to − 150 V. Indeed, the variation of grain sizes from 24 to 16 nm as well as the residual stresses from − 0.68 to − 8.94 GPa lead to obtain different mechanical–tribological properties. In this context, the sample deposited at − 100 V exhibited an enhanced hardness (50 ± 2 GPa) and an acceptable wear resistance

Développement de matériaux pour les piles à combustibles SOFC

Dans le cadre des nouveaux programmes du CEA dédiés aux Nouvelles Technologies pour l'Energie, l'un des axes concerne les piles à combustible haute température et tout solide (SOFC). Deux voies de recherche sont présentées ici ; l'une traite de l'élaboration d'électrolytes connus - de type zircone yttriée - en couche mince, par des techniques de dépôt PVD ou CVD à injection, ceci dans le but d'un fonctionnement à plus basse température. L'autre a trait au développement de matériaux d'anode compatibles avec l'utilisation directe du méthane à la place de l'hydrogène. Les chromates de lanthane substitué par le strontium, dont une méthode de synthèse sous forme de poudres très divisées est présentée ici, semblent être des matériaux prometteurs pour cette application, à condition qu'ils ne subissent pas de dégradation en fonctionnement

Mini et micro-batteries

La miniaturisation de l'électronique portable requiert des sources d'énergie de taille plus en plus réduite. C'est la raison pour laquelle le Commissariat à l'Energie Atomique (CEA), grâce à ses compétences dans les différents domaines techniques concernés (énergie, électrochimie, matériaux, microélectronique), conduit des études pour développer deux types de batterie secondaire innovante : les mini et les micro-batteries au lithium. Les travaux menés au CEA sur ces deux types d'objet ainsi que les développements envisagés sont présentés dans cet article

Cathodic arc deposited (Cr,Six)N coatings: From solid solution to nanocomposite structure

cited By 5International audienceThis paper aims to investigate the effect of silicon addition on the microstructure and mechanical properties of CrN coatings with an emphasis on their stability at high temperature. Thin films were deposited onto M2 tool steels using a cathodic arc deposition process. Silicon was introduced using duplex Cr-Cr3Si targets, allowing Si enrichment within the 0.6-10.8at.% range.The microstructure of the films was characterized by SEM and TEM, while their crystalline structure at room temperature and after high temperature annealing treatments (up to 1000. °C) was determined by XRD analyses. Mechanical properties were deduced from nanoindentation measurements and from residual stress experiments.A minimum content of 2at.% was evidenced as the solubility limit of Si in CrN. Below this value, Si substituted Cr in the CrN lattice to form a solid solution. Above 2at.% Si, a nanocomposite bi-phased structure appeared, composed of Si-poor CrN nanograins surrounded by an amorphous Si-rich CrN matrix. Si addition induced significant grain shrinkage, without a significant effect on hardness at room temperature. For (Cr,Six)N films annealed at high temperatures, the nanocomposite structure allowed a delay in structural transformations linked to nitrogen losses, preserving better and more stable mechanical properties. © 2012 Elsevier B.V

Properties of TiSiN coatings deposited by hybrid HiPIMS and pulsed-DC magnetron co-sputtering

International audienceTiSiN nanocomposites coatings were synthesized for the first time by a hybrid deposition technique where high power impulse (HiPIMS) and pulsed-DC (PDCMS) magnetron co-sputtering were used for Ti and Si deposition respectively in an Ar + N-2 atmosphere. For the Ti target, the deposition parameters were fixed, while the current applied to the Si target ranged from 0 to 0.9 A. Thus, the Si content in the films was adjusted from 0 to 8.8 at.% Si to allows tailoring of microstructure and mechanical properties. TiSiN grain sizes decreased from similar to 41 to similar to 6 nm as the coatings became more siliceous. The hardness increased from 20 +/- 0.41 to 41.31 +/- 2.93 GPa when the Si concentration rose from 0 to 4.4 at.% Si, but beyond this last value, hardness degrades reaching 36.1 +/- 2.21 GPa at 8.8 at.% Si. The wear behaviours evaluated by ball-on-disc tests were correlated with the Hardness/Young's modulus ratio. Moreover, the silicon enhanced the oxidation resistance and the least hardness deterioration was found in the sample with the higher silicon content (8.8 at.% Si) after a thermal annealing in air (2 h/700 degrees C). (C) 2014 Elsevier Ltd. All rights reserved

Microstructural, thermal and mechanical behavior of co-sputtered binary Zr–Cu thin film metallic glasses

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