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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Investigation Of Reactively Sputtered Boron Carbon Nitride Thin Films

Todi, Vinit O 01 January 2011 (has links)
Research efforts have been focused in the development of hard and wear resistant coatings over the last few decades. These protective coatings find applications in the industry such as cutting tools, automobile and machine part etc. Various ceramic thin films like TiN, TiAlN, TiC, SiC and diamond-like carbon (DLC) are examples of the films used in above applications. However, increasing technological and industrial demands request thin films with more complicated and advanced properties. For this purpose, B-C-N ternary system which is based on carbon, boron and nitrogen which exhibit exceptional properties and attract much attention from mechanical, optical and electronic perspectives. Also, boron carbonitride (BCN) thin films contains interesting phases such as diamond, cubic BN (c-BN), hexagonal boron nitride (h-BN), B4C, β-C3N4. Attempts have been made to form a material with semiconducting properties between the semi metallic graphite and the insulating h-BN, or to combine the cubic phases of diamond and c-BN (BC2N heterodiamond) in order to merge the higher hardness of the diamond with the advantages of c-BN, in particular with its better chemical resistance to iron and oxygen at elevated temperatures. New microprocessor CMOS technologies require interlayer dielectric materials with lower dielectric constant than those used in current technologies to meet RC delay goals and to minimize cross-talk. Silicon oxide or fluorinated silicon oxide (SiOF) materials having dielectric constant in the range of 3.6 to 4 have been used for many technology nodes. In order to meet the aggressive RC delay goals, new technologies require dielectric materials with K
62

Développement de couches minces super-élastiques à base de titane obtenues par pulvérisation cathodique magnétron / Development of superelastic titanium-based thin films obtained by magnetron sputtering

Achache, Sofiane 18 February 2016 (has links)
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 / 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

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