Magdeburg, Universiẗat, Diss., 2004.

Les films nanocomposites sont des revêtements composés de nanoparticules enrobées dans une matrice solide d’un matériau différent. L’intérêt de ces matériaux réside dans leur capacité à exploiter les caractéristiques inédites des nano-objets qu’ils contiennent tout en bénéficiant des propriétés de résistance mécanique et chimique de la matrice. Ces composites disposent de propriétés très prometteuses pour un grand nombre d’applications comme le photovoltaïque ou la photocatalyse. Plusieurs procédés de synthèse existants permettent de produire des matériaux nanocomposites par des méthodes physiques ou chimiques (co-pulvérisation, sol-gel,…). Cependant, aucun n’est assez flexible pour envisager la synthèse d’une large gamme de nanocomposites par le même procédé. Ceci est un frein au développement à l’échelle industrielle de ce type de matériaux. Le premier objectif de la thèse est de développer un procédé original de synthèse de films nanocomposites. Ce procédé présente un caractère universel en ce qu’il permet un choix a priori illimité dans la nature des nanoparticules et celle de la matrice. Le procédé développé combine un jet de nanoparticules sous vide formé par une lentille aérodynamique à un dispositif de pulvérisation magnétron qui permet de déposer la matrice. Le jet de nanoparticules permet de coupler toute source de nanoparticules à la pulvérisation. Les nanoparticules peuvent être soit synthétisées in situ en phase gazeuse, soit synthétisées préalablement en voie liquide. Une grande variété de nanoparticules peut donc être utilisée. La pulvérisation magnétron permet par ailleurs de disposer d’une très large gamme de matériaux pour la matrice (métaux, céramique, polymère). Dans le cadre de cette thèse, deux types de sources de nanoparticules ont été utilisés. Le premier est un réacteur de pyrolyse laser et le second un générateur d’aérosol. Le réacteur de pyrolyse laser permet une synthèse in-situ des nanoparticules en phase gazeuse alors que le générateur d’aérosol permet d’utiliser une suspension de nanoparticules préalablement synthétisées. Afin d’éprouver la robustesse du procédé de co-dépôt, deux types de matériaux nanocomposites ont été développés. Le premier matériau étudié est composé de nanoparticules d’or sphériques de 35 nm de diamètre, synthétisées préalablement par voix liquide, dans une matrice de silice. Le but ici est de bénéficier des propriétés optiques uniques des nanoparticules d’or dans un film résistant mécaniquement et chimiquement. Les caractérisations réalisées sur ces matériaux ont permis d’optimiser la concentration en nanoparticules d’or dans les films de manière à garder des propriétés mécaniques et chimiques compatibles avec les applications tout en gardant des propriétés optiques satisfaisantes. Le second type de matériaux étudiés est composé de nanoparticules semi-conductrices synthétisées in situ par pyrolyse laser et d’une matrice métallique. La synthèse de ce matériau permet de démontrer la flexibilité du procédé de co-dépôt à synthétiser une large gamme de films nanocomposites. Enfin, la robustesse du procédé ayant été démontrée, la conception d’un pilote industriel a été entreprise. Le but final étant de disposer d’une machine répondant aux exigences industrielles dans l’optique d’un transfert technologique. / The nanocomposite films are coatings of nanoparticles embedded in a solid matrix of a different material. The advantage of these materials is their ability to exploit the unique properties of nano-objects while benefiting of the mechanical and chemical resistance properties of the matrix. These composites have very promising properties for many applications such as photovoltaics and photocatalysis. Several existing synthetic methods can produce nanocomposite materials by physical or chemical methods (co-sputtering, sol-gel, ...). However, none is flexible enough to consider the synthesis of a wide range of nanocomposites by the same method. This is an obstacle to the development on an industrial scale of this type of material. The first objective of the thesis is to develop an original synthesis process of nanocomposite films. This method is universal in which it presents no limit in the choice of nanoparticles and matrix. The developed method combines vacuum nanoparticle jets formed by an aerodynamic lens with a magnetron sputtering device for depositing the matrix. The nanoparticle jets can be coupled with any source of nanoparticles. Nanoparticles may be synthesized in situ in the gas phase or beforehand solution synthesis. A wide variety of nanoparticles can be used. Magnetron sputtering also enables to have a very wide range of materials for the matrix (metal, ceramic, polymer). During this thesis, two types of nanoparticles sources were used. The first one is a laser pyrolysis reactor and the second is an aerosol generator. The laser pyrolysis reactor enables in-situ gas phase synthesis of the nanoparticles while the aerosol generator use a suspension of previously synthesized nanoparticles. To test the robustness of the co-deposition process, two types of nanocomposite materials have been developed. The first material is composed of 35 nm spherical gold nanoparticles, chemically synthesized, in a silica matrix. The goal here is to benefit from the unique optical properties of gold nanoparticles in a film mechanically and chemically resistant. The characterizations carried out on these materials have optimized the gold nanoparticle concentration in the films to keep the mechanical and chemical properties compatible with applications while maintaining satisfactory optical properties. The second type of materials studied is composed of semiconductor nanoparticles in situ synthesized by laser pyrolysis and a metal matrix. The synthesis of this material demonstrates the flexibility of the co-deposition method to synthesize a wide variety of nanocomposite films. Finally, the design of an industrial pilot was undertaken. The final goal is to have a pilot-scale setup that meets industry requirements in the context of a technology transfer.

We use molecular beam deposition (MBD) system to grows bi-layers CuInSe2-based thin film solar cell, soda-lime glass as our substrate, cadmium sulfide(CdS) as our buffer layer, zinc oxide(ZnO) as window layer, Mo as back contact metal and using Al as front contact metal. In our device fabrication process, we primary use physical vapor deposition(PVD) to grows thin film in vacuum condition expect Cadmium sulfide. We already fabricate the CdS/CuInSe2-based thin film solar cell successful. Using current-voltage measurement to get fill factor(F.F.) is 39.76%, open circuit voltage(Voc) is 0.26V and short circuit current(Isc) is 2.104mA in our device. It¡¦s so essential to improve every layers properties in order to get higher quantum efficiencies. Especially, resistivity of the zinc oxide window layer is too high and the interface properties between Al and ZnO is not so good. The junction perfection factor is 1.9161, recombination current is the dominate current. So, research and further improve interface characterization between CuInSe2/CdS is necessary.

Tübingen, Univ., Diss., 2007.

Universiẗat, Diss., 2002--Kiel.

In the given coating chamber is a system of rotating holders, which holds rotating tools. The chamber also contains electrodes (of various materials), from which the material evaporates and is coating the tools. The goal of this thesis is to simulate the process of coating and visualize the resulting layer in given places of coated tools depending on their placement, number, rotation speed and other optional settings.

The development of nanostructured coatings which exhibit enhanced mechanical properties is currently of interest due to the importance of high performance coatings in a large range of applications. Single layer coatings have predominantly been used for these demanding applications, however the promising mechanical properties observed in multilayer coatings has shifted the focus of current research. In particular, there has been reports of the use of alternating materials with opposing mechanical properties, as seen in the abalone shell, which have exhibited hardness and toughness values significantly greater than either of their constituent materials. The main objective of this thesis was to fabricate Al/W nanostructured multilayers and determine if they exhibit enhanced mechanical properties. The Al/W nanostructured multilayers were fabricated using two different deposition techniques: pulsed magnetron sputtering and cathodic arc deposition. These two techniques differ in the energy of the depositing species and this results in significant differences in film properties. The indentation hardness of the coatings was measured using a Hysitron Nanoindenter. The relationship between the mechanical properties and microstructure was obtained using a range of characterisation techniques. Auger electron spectroscopy (AES), energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS) were used to determine the chemical composition and stoichiometry, while cross-sectional transmission electron microscopy (XTEM) and energy filtered transmission electron microscopy (EFTEM) were used to explore the microstructure. The findings of this thesis showed very different results for the two deposition techniques. Although sputtering successfully produced well defined multilayers, no evidence of enhanced hardness was found for periods between 5 and 200 nm. On the other hand, arc deposited samples with intended periods between 1 and 200 nm showed a hardness enhancement above that of pure W, however the samples of highest hardness did not contain Al layers for much of their thickness. Arc deposited samples with the finest nominal periods (1 and 2 nm) contained W-Al intermetallics and were soft. The hardening mechanism was not attributed to a multilayer structure, rather to the introduction of defects in the W layers which acted as pinning sites for dislocations. A modified Hall-Petch equation for hardness enhancement fitted the data for W films prepared by pulsed cathodic arc in which the grain diameter was replaced by the nominal multilayer period. The difficulty producing Al layers on W surfaces in the cathodic arc was overcom e by changing the film growth mechanism by introducing Ar or O2 at the W/Al interface. In the latter case, Al2O3/W multilayers were formed but again showed no hardness enhancements. Complete microanalysis and characterisation of the multilayer structures is vital in determining the mechanisms which govern the hardness enhancements. The evidence in this thesis suggests that the defect density, and not the presence of interfaces are responsible for the hardness enhancement effect.

Zugl.: Aachen, Techn. Hochsch., Diss., 2006.

Zugl.: Stuttgart, Univ., Diss., 2003.

Mimicking nature gives rise to many important facets of biomaterials. This study is inspired by nature and reports on the fabrication of an intercalated polymer-NiTi nanocomposite that mimics the structural order of urethral tissue performing micturition. PTFE is chosen due to its hydrophobicity, low surface energy, and thermal and chemical stability. NiTi has been selected as a prime candidate for this research due to its excellent mechanical stability, corrosion resistance, energy absorbance, shape memory and biocompatibility. Nanoscale engineering of intercalated nanocomposites is done by PVD sputtering PTFE and NiTi. FTIR spectroscopy confirms that PTFE reforms as polymer chains after sputtering. Suitable PVD sputtering parameters were selected by investigating their influence on deposition rates, microstructure and properties of PTFE and NiTi thin films. PTFE forms stable nanocomposite coatings with NiTi and displays favourable surface interactions, known as ‘intercalation’. Intercalated PTFE-NiTi films were fabricated as layered and co-sputtered thin films. Co-sputtered nanocomposites contained nearly one-third vacant sites within its internal microstructure because of intercalation while intercalation introduced minute pits in fibrous NiTi columns of layered nanocomposites. These pits allow PTFE to extend their chains and crosslinks, resulting in microstructural and functional changes in the thin films. Intercalated PTFE-NiTi nanocomposites offer a close match to the natural tissue in terms of responding to the fluid contact (wetting angle modifications), and allow the soft and hard matter to incorporate in one framework without any chemical reactions (intercalation). An intercalated microstructure in co-sputtered and layered nanocomposites was verified by EDS-SEM and EDS-TEM techniques. The functional responses were witnessed by changes in water contact angle (WCA) and coefficient of friction (CoF) values measured on the film surface. The WCA (99°) and CoF (0.1 – 0.2) of the intercalated nanocomposite (sample PNT12) were different to the NiTi (top layer). WCA and CoF indicate the internal microstructural interactions because of intercalation. Although the pseudoelastic behaviour of NiTi can provide additional fluid response but the difficulty is an absence of crystallinity in as-deposited NiTi, and the heat treatment that melts PTFE. However, DSC and XRD techniques were employed to find the optimum NiTi composition and transition temperatures for phase transformation related to pseudoelasticity. This study provides the basis to incorporate the shape memory (pseudoelasticity or thermal shape memory effect (shape memory effect)) features of NiTi into the intercalated nanocomposite in future. The intercalated PTFE-NiTi nanocomposite reveals a fascinating research precinct, having the response generating characteristics similar to that of natural tissue.