Thesis (M.S.)--Rochester Institute of Technology, 1981. / Typescript. Includes bibliographical references (leaves 52-53).

Thesis (M.S.)--Rochester Institute of Technology, 1988. / Typescript. Includes bibliographical references (leaves 59-61).

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 31-34).

Thesis (M.S.)--Rochester Institute of Technology, 1992. / Typescript. Includes bibliographical references (leaves 32-34).

Im Rahmen der vorliegenden Arbeit wird eine neue, kostengünstige und effiziente Strategie zur selektiven Beschichtung gedruckter Muster auf Papier entwickelt. Mittels Phagen-Display werden Peptide identifiziert, die materialspezifische Adsorption zeigen und effektiv zwischen Cellulose als Hauptbestandteil von Papier und dem Toner eines mit einem handelsüblichen Laserdrucker gedruckten Musters unterscheiden können. Diese genetisch selektierten 12mer Peptide können selektiv entweder nicht bedruckte Cellulose oder gedruckte Tonerstrukturen beschichten. Es werden vielfältige Adsorptionsuntersuchungen einzelner Peptide an den jeweiligen separaten Oberflächen und an gedruckten Mustern durchgeführt und diskutiert. Des Weiteren wird eine Ligationschemie mit Triazolindion genutzt, um z. Bsp. Farbstoffe oder funktionale Peptide selektiv auf einer Oberflächenbeschichtung zu lokalisieren. Diese Methodik bietet einen einfachen Zugang zur Funktionalisierung von Mustern auf papierbasierten Materialien, wodurch neue Wege zur Realisierung kostengünstiger diagnostischer oder biomedizinischer Geräte aufgezeigt werden können. / Within the scope of this thesis, a new, cost-effective and efficient strategy for the selective coating of printed patterns on paper is developed. Phage display biopanning identifies peptides that show material selective adsorption, effectively distinguishing between cellulose of paper and printed toner of standard office laser printers. These genetically selected 12mer peptides can selectively coat either non-printed cellulose or printed toner patterns. Numerous adsorption studies of individual peptides on the respective separated surfaces and on printed patterns are carried out and discussed. Furthermore, triazolindione ligation chemistry is exploited to introduce e.g. dyes or functional peptides selectively to the coatings. The strategy offers an easy access toward patterned functionalization of paper based materials, which potentially is of relevance for low cost diagnostics or biomedical devices.

Ces travaux de thèse rentrent dans le cadre de l'ANR Photoflex (2013-2016) qui vise à mettre au point une technologie d'impression laser sans contact, pour créer des motifs actualisables ou permanents à caractère unique sur tout type de support, en particuliers des supports souples. Nous rapportons la synthèse par technique de pulvérisation magnétron en mode réactif et à température ambiante de films minces nanocomposites photochromes constitués de nanoparticules d'Ag entre deux couches nanoporeuses de TiO2. Ces films sont déposés sur des substrats souples tels qu'un plastique transparent (PET) et un papier diffusant. Nous montrons que lorsque le TiO2 est élaboré en régime de pulvérisation élémentaire, le film nanocomposite est coloré en raison de la présence de nanoparticules d'Ag métalliques induisant une résonance de plasmons de surface localisés dans le visible. En revanche, en régime de pulvérisation composite, le film nanocomposite est incolore car l'Ag s'oxyde lors de son recouvrement par le TiO2. Nous avons démontré que les échantillons incolores peuvent se colorer sous insolation laser UV (244 nm) dû à la réduction de l'Ag oxydé puis à la croissance de nanoparticules d'Ag métalliques par coalescence ou par mûrissement d'Ostwald. De plus, l'insolation laser visible (647 nm) à de faibles éclairements (quelques W.cm-2) de ce type de film ou des films initialement colorés donne lieu à des changements morphologiques des nanoparticules d'Ag qui modifient l'absorbance du film et entraînent une modification de la coloration de l'échantillon. Nous avons étudié l'influence des conditions de dépôt (épaisseur de la couche de recouvrement des nanoparticules, épaisseur de la sous-couche de TiO2, quantité d'Ag, temporisation après dépôt d'Ag, traitement plasma des nanoparticules d'Ag, multicouches) afin d'optimiser les effets de photochromisme en amplitude et en vitesse. Tous les mécanismes de photochromisme sont répétables durant des processus cycliques d'insolation UV/Visible. Pour de forts éclairements en laser visible (plusieurs dizaines de kW.cm-2), nous avons observé sur des films nanocomposites déposés sur verre, des changements de couleurs dépendants de la direction de polarisation du faisceau sonde, liés à la croissance thermique et à l'auto-organisation de l'Ag selon un réseau périodique de chaînes de nanoparticules. Contrairement aux faibles éclairements, les couleurs photo-induites sont permanentes et présentent un caractère dichroïque. Cette étude ouvre des perspectives intéressantes en termes d'applications, notamment pour l'authentification et la traçabilité de produits manufacturés, le stockage de données, les nouvelles générations de datamatrix, etc. / These thesis works are within the framework of the ANR Photoflex (2013-2016), which aims to develop a contactless laser printing technology, in order to create updatable or permanent patterns of unique character on any types of supports, especially flexible supports. We report on a reactive magnetron sputtering-based deposition method to synthesize, at room temperature, photochromic nanocomposite thin films consisting of Ag nanoparticles sandwiched between nanoporous TiO2 layers. These films are deposited on flexible substrates such as a transparent plastic (PET) and a diffusing paper. We show that when the TiO2 is elaborated in the metallic sputtering mode, the nanocomposite film is colored due to the formation of metal Ag nanoparticles inducing a localized surface plasmon resonance in the visible range. In contrast, in the compound sputtering mode, the nanocomposite film is colorless because the Ag nanoparticles are oxidized during their capping by the TiO2. We have demonstrated that the colorless samples can be colored under UV laser irradiation (244 nm) due to the reduction of oxidized silver, followed by the growth of metallic Ag nanoparticles by coalescence or Ostwald ripening. Moreover, visible laser irradiation at low irradiances (few W.cm-2) of the colored films gives rise to changes in the particle morphology that modifies the absorbance of the films and results in sample color changes. We have investigated the influence of the deposition conditions (capping layer thickness of nanoparticles, TiO2 buffer layer thickness, Ag amount, holding time after Ag deposition, plasma annealing of Ag nanoparticles, multilayer) in order to optimize the photochromic effects in amplitude and in speed. All the mechanisms are repeatable during UV/Visible irradiation cyclic processes. For strong visible laser irradiances (several tens of kW.cm-2), we observed on nanocomposite films deposited on glass, color changes dependent on the polarization direction of the probe beam, related to the thermal growth and to the self-organization of Ag according to a periodic grating of nanoparticle chains. Contrary to low irradiances, the photo-induced colors are permanent and have a dichroic character. This study opens up interesting possibilities in terms of applications, including authentication and traceability of manufactured products, data storage, the new generation of datamatrix, etc.

No description available.

[pt] A presente tese tem como objetivo estudar a estabilidade microestrutural da superliga 625 a base de Ni pelas suas propriedades mecânicas e suas várias aplicações na indústria, em três condições distintas: maciça (placa forjada industrialmente), partículas de pó precursora da peça 3D e uma peça produzida por impressão a laser (Deposição Direta de Metais - DMD). Amostras destas condições foram submetidas a tratamentos de solubilização e envelhecimento isotérmico a 650 graus Celsius e 750 graus Celsius durante 10 horas e 100 horas, de modo a promover fenômeno de precipitação e, assim, correlacionar com as propriedades mecânicas do material. A caracterização microestrutural foi realizada por microscopia ótica (MO), microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (MET) no modo convencional utilizando contraste de difração, na modalidade analítica de transmissão/varredura (STEM), e em alta resolução (HRTEM). Espectroscopias de raios X por dispersão em energia (EDS) e de perdas de energia de elétrons (EELS) foram utilizadas para analisar a composição local da matriz e das fases presentes. Foram realizados ensaios de microdureza para avaliar o efeito dos tratamentos térmicos. A análise microestrutural da amostra maciça na condição como recebida apresentou grãos equiaxiais com fases NbTiC e M6C. Com o tratamento térmico de solubilização a 1100 graus Celsius por 40 minutos houve uma dissolução parcial dos carbetos. O envelhecimento a 650 graus Celsius por 10 horas resultou em carbetos de NbTiC e um aumento da dureza em 5 porcento em relação a amostra como solubilizada. Entretanto no tratamento de envelhecimento a 100 horas ocorreu precipitação homogênea da fase gama aumentando a dureza do material em 45 porcento, se comparada à mesma como solubilizada. A liga maciça envelhecida a 750 graus Celsius por 10 horas apresentou os carbetos NbTiC e M23C6 nos contornos de grãos e dispersos na matriz. Já a liga maciça envelhecida por 100 horas a esta mesma temperatura, apresentou a fase δ dispersa na matriz. A análise microestrutural do pó precursor mostrou ser policristalino constituído predominantemente de grãos colunares da matriz austenítica. Análises das amostras produzidas por DMD como recebida revelou estrutura dendrítica com carbetos de Nb e fase Laves nas regiões interdendríticas. A solubilização das amostras DMD durante 40 minutos por 1100 graus Celsius e 1200 graus Celsius mostrou ser insuficientes para a dissolução dos precipitados. A fim de melhorar a difusão do Nb e a dissolução dos carbetos e da fase Laves, foi realizado o tratamento de solubilização a 1200 graus Celsius por 100 horas. Esta amostra tratada a 650 graus Celsius por 100 horas apresentou carbetos M23C6 precipitados nos contornos de grão e nas interfaces entre matriz CFC e a fase Laves. Entretanto, no envelhecimento a 750 graus Celsius durante 100 horas ocorreu à precipitação dos carbetos M23C6 e M6C nos contornos de grão e dispersos na matriz, aumentando assim a dureza do material em 18 porcento, se comparada à mesma como solubilizada. O aumento da microdureza em 12 porcento após o tratamento térmico está relacionado à precipitação dos carbetos nos contornos de grão e dispersos na matriz resultado dos tratamentos térmicos de envelhecimento. / [en] This thesis studies the microstructural stability of Ni-base Super alloy 625 for its mechanical properties and its varieties of applications in the industry, in three different conditions: bulk (industrially forged plate), precursor powder particles for 3D printing process and a sample produced by laser Direct Metal Deposition (DMD). Aiming at promoting precipitation processes and, therefore, correlate with the mechanical properties of the material, samples of these conditions were submitted to solution annealing and isothermal aging treatments at 650 Celsius degrees and 750 Celsius degrees for 10 hours and 100 hours. Characterization of the microstructure was performed by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), in the conventional diffraction contrast mode, scanning/transmission (STEM) analytical mode, and high resolution microscopy (HRTEM). Energy dispersive X-ray spectrometry (EDXS) and electron energy loss spectroscopy (EELS) were used to analyze the local composition of the matrix and precipitated phases. Micro hardness measurements were performed to evaluate the effect of thermal treatments. The microstructural analysis of the bulk sample in the as-received condition showed an equiaxial grain structure with NbTiC and M6C precipitated phases. Solid solution treatment at 1100 Celsius degrees for 40 minutes allowed partial dissolution of the carbides. Aging at 650 Celsius degrees for 10 hours showed NbTiC carbides and a hardness increase of 5 percent compared to the as-solubilized sample. However, aging at this temperature for 100 hours promoted the homogeneous precipitation of the gama phase, thus increasing the material s hardness by 45 percent, when compared to it as solubilized. The bulk sample aged at 750 Celsius degrees for 10 hours showed grain boundary and homogeneous precipitation of NbTiC and M23C6 carbides. This sample condition upon aging at this temperature for 100 hours shows δ phase homogeneously precipitated in the matrix. The microstructural analysis of the precursor powder showed micrometer size individual particles as polycrystalline, consisting predominantly of columnar grains of the austenitic matrix. Analysis of samples produced by DMD in the as-received condition revealed dendritic microstructure with carbides of Nb and Laves phase in the interdendritic regions. The solution treatment of the DMD samples for 40 minutes at 1100 Celsius degrees and 1200 Celsius degrees proved to be insufficient for the dissolution of the precipitate. In order to enhance diffusion of Nb and so carbide and Laves phase dissolution, a solution anneal was carried out at 1200 Celsius degrees for 100 hours. This sample treated at 650 Celsius degrees for 100 hours showed M23C6 carbides precipitated at grain boundaries and also at the Laves phase/matrix interfaces. However, upon aging at 750 Celsius degrees for 100 hours the precipitation of M23C6 and M6C takes place at the grain boundary and in the austenitic matrix, thus increasing the material s hardness by 18 percent, when compared to it as solubilized. The increase of the hardness by 12 percent after the heat treatment is related to the precipitation of the carbides in the grain boundaries and dispersed in the matrix resulting from the aging thermal treatments.