This thesis is devoted to the investigation of ion generation and fluxes from cathodic arc spots for a better understanding of energetic deposition of thin film. The ion generation is related to the arc spot properties, and ion fluxes influence the film deposition. Significantly, the cathodic arc has the explosion characteristic for the ignition process, which is the generation process of ions. Thus, it is not easy to observe the spot characteristics, and some fundamental questions related to cathodic arc spot motion are still open. The multiply charged ions produced from the arc spot ignition process have a higher ion potential energy than ions of other deposition techniques; therefore, consideration of the effect of ion potential energy on film growth is required for the cathodic arc technique. The first part of this thesis deals with fundamental arc spot characteristics, especially the trend of spot motion in a magnetically steered arc source placed in vacuum or in a reactive gas atmosphere. This is investigated with a streak camera having high spatial and temporal resolutions. To answer the fundamental question of whether the spots have characteristic times, such as a 'periodic spot lifetime' or a 'the periodic characteristic time between spot ignitions”, the streak images were analyzed by fast Fourier transformation (FFT). It was found that the power spectrum of the arc spot fluctuations does not show any specific frequencies, which means the arc spot ignition process can be described by a fractal model, and the spectral slope in the log-log power-frequency diagram has a tendency to be reduced in the presence of a compound (for example oxide or nitride) layer on the cathode surface. Through the fractal analysis and measurements of optical emission spectroscopy, the fundamental limitation of the temporal resolution for the optical emission method is determined and considered. The second part of this thesis considers cathodic arc’s application aspects: the energetic deposition of thin films and coatings. Most studies related to energetic deposition have previously investigated the effects of ion kinetic energy on film deposition; however, this thesis focuses on the effects of ion potential energy on film growth. To investigate the effect of ion potential energy on film growth, plasma diagnostic by energy-resolved mass spectrometry and deposited film characterization by XRD, XRR, AFM, profilometry and SEM were carried out. The ion potential energy influences the preferential direction of film growth or a polycrystalline growth in the case of aluminum deposition. This result could be a starting point for further research into the effect of ion potential energy on film deposition.

The speed and complexity of globalisation and reduction of natural resources on the one hand, and interests of large multinational corporations on the other, necessitates proper management of mineral resources and consumption. The need for scientific research and application of new methodologies and approaches to maximise Net Present Value (NPV) within mining operations is essential. In some cases, drill core logging in the field may result in an inadequate level of information and subsequent poor diagnosis of geological phenomenon which may undermine the delineation or separation of mineralised zones. This is because the interpretation of individual loggers is subjective. However, modelling based on logging data is absolutely essential to determine the architecture of an orebody including ore distribution and geomechanical features. For instance, ore grades, density and RQD values are not included in conventional geological models whilst variations in a mineral deposit are an obvious and salient feature. Given the problems mentioned above, a series of new mathematical methods have been developed, based on fractal modelling, which provide a more objective approach. These have been established and tested in a case study of the Kahang Cu-Mo porphyry deposit, central Iran. Recognition of different types of mineralised zone in an ore deposit is important for mine planning. As a result, it is felt that the most important outcome of this thesis is the development of an innovative approach to the delineation of major mineralised (supergene and hypogene) zones from ‘barren’ host rock. This is based on subsurface data and the utilisation of the Concentration-Volume (C-V) fractal model, proposed by Afzal et al. (2011), to optimise a Cu-Mo block model for better determination of an ultimate pit limit. Drawing on this, new approaches, referred to Density–Volume (D–V) and RQD-Volume (RQD-V) fractal modelling, have been developed and used to delineate rock characteristics in terms of density and RQD within the Kahang deposit (Yasrebi et al., 2013b; Yasrebi et al., 2014). From the results of this modelling, the density and RQD populations of rock types from the studied deposit showed a relationship between density and rock quality based on RQD values, which can be used to predict final pit slope. Finally, the study introduces a Present Value-Volume (PV-V) fractal model in order to identify an accurate excavation orientation with respect to economic principals and ore grades of all determined voxels within the obtained ultimate pit limit in order to achieve an earlier pay-back period.

L'agglomération humide est une étape cruciale dans la technologie de mise en forme des poudres de par son fort impact sur la qualité finale des produits élaborés. Malgré son intérêt lors de l'élaboration de nombreux produits (aliment, pharmaceutique, génie civil,…), ainsi que les différents modes technologiques (malaxeurs horizontaux, verticaux, à faible ou fort de taux de cisaillement, lit fluidisé, …), elle reste insuffisamment maîtrisée de par la difficulté à proposer des diagrammes de fonctionnement opérationnels qui couplent les contributions croisées des procédés et des produits. Ce travail de thèse s'inscrit dans cette problématique et porte sur l'étude des mécanismes d'agglomération en lien avec les caractéristiques de la formulation et les paramètres opératoires. L'identification et la représentation du mode d'assemblage des particules au cours de l'opération de mouillage/malaxage est l'un des enjeux central de ce travail. A partir d'expériences menées avec deux types de poudres alimentaires (semoule de blé dur et poudre de lait), l'agglomération est induite soit par contacts humides en malaxeur à faible taux de cisaillement soit par des collisions entre les particules collantes en lit fluidisé. Les mécanismes d'agglomération humide de la semoule de blé dur développés dans un malaxeur à faible cisaillement sont décrits selon un processus de morphogénèse qui corrèle la taille des agglomérats à leur texture via une dimension fractale. L'influence des propriétés physicochimiques des liants liquides sur les mécanismes d'agglomération est étudiée au regard des paramètres du modèle fractal. L'étude fine des distributions des propriétés hydrotexturales et dimensionnelles des structures agglomérées a permis d'identifier leur « règle » d'agencement : association par même classe hydro-texturale et dimensionnelle. Les régimes d'agglomération en fonction du mode d'apport d'eau (débit faible, débit fort) sont étudiés en se basant sur la notion de flux d'atomisation adimensionné. En ce qui concerne l'agglomération de la poudre de lait en lit fluidisé, les mécanismes d'agglomération sont étudiés en suivant l'évolution des tailles et des teneurs en eau des échantillons prélevés durant l'opération de mouillage/séchage et par la suite l'étude de l'impact de certaines conditions opératoires et de formulation sur les propriétés des agglomérats finaux et les régimes d'agglomération. Un lien entre les procédés est discuté et ouvre sur une requalification des régimes d'écoulement granulaire ainsi que de la réactivité de surface des particules. / Wet agglomeration is a crucial step in the shaping technology of powders because of its strong impact on the final quality of the elaborated products. Despite its interest in the elaboration of many products (food, pharmaceutical, engineering,...) as well as different technological process (horizontal mixers, vertical, low or high shear rate, fluidized bed, ...), it remains insufficiently mastered due to the difficulty in establishing operating diagrams taking into account, in the same time, products and process contributions. This thesis focuses on the study of the agglomeration mechanisms related to the characteristics of the formulation and process parameters. The identification and representation of the way particles come together during the wetting / mixing operation is one of the central challenges of this work. From experiments with two different food powders (durum wheat semolina and milk powder), agglomeration is induced either by wet contacts in mixer at low shear rate or by collisions between sticky particles in a fluidized bed. Mechanisms of semolina wet agglomeration developed in a low shear mixer are described as a process of morphogenesis that correlates the agglomerates size to their texture via a fractal dimension. The influence of the liquid binder physicochemical properties on the agglomeration mechanisms is studied according to the values taken by the fractal parameters of the model. The detailed study of the distribution of size and textural properties of agglomerated structures make it possible to identify the rule that lead to their layout: the association is mainly possible between structures belonging to the same class concerning their hydro-textural and dimensional characteristics. Agglomeration regimes depending on the mode of water supply (low flow, high flow) are studied based on the notion of dimensionless spray flux. Concerning milk powder agglomeration in a fluidized bed, agglomeration mechanisms are studied by following the evolution of the size and water content of the samples taken during the operation of wetting / drying and thereafter studying the impact of some operational conditions and formulation on the properties of the final agglomerates and agglomeration regimes. A link between the processes (low shear mixer and fluidized bed) is discussed and opens onto a redefinition of granular flow regimes and the surface reactivity of particles.

Made available in DSpace on 2017-07-10T19:24:55Z (GMT). No. of bitstreams: 1 Gilberto Comiran.pdf: 1846926 bytes, checksum: 1b96f9d3924516f3c3a1814a89cd0014 (MD5) Previous issue date: 2006-07-21 / In this work, it is shown an application of a model to obtain the hydraulic conductivity of soils no saturated using concepts Fractal Geometry and the laws of Laplace and of Poiseuille. For the obtaining of the soil water retention curve it was used the camera of pressure of Richards and the experimental data of hydraulic conductivity in function of the soil water content were obtained through the Method of Hillel with the tensiometry use, according to a potency model. The equation van Genuchten with their parameters was used for the obtaining of the hydraulic conductivity. The application of the models of the Geometric Average and of the Neutral Pore suggested by Fuentes was shown simple and capable of predicting the hydraulic conductivity satisfactorily. / Neste trabalho, apresenta-se a aplicação de um modelo para se estimar a condutividade hidráulica de solos não saturados, utilizando os conceitos da Geometria Fractal e das leis de Laplace e de Poiseuille. Para a obtenção da curva de retenção de água, foi utilizada a câmara de pressão de Richards e os dados experimentais de condutividade hidráulica, em função da umidade do solo, foram obtidos através do Método de Hillel com a utilização de tensiometria, conforme um modelo de potência. A equação de van Genuchten, com seus parâmetros, foi utilizada para a obtenção da condutividade hidráulica. A aplicação dos modelos da Média Geométrica e do Poro Neutro sugerido por Fuentes mostrou-se simples e capaz de predizer a condutividade hidráulica satisfatoriamente.

Made available in DSpace on 2017-05-12T14:48:17Z (GMT). No. of bitstreams: 1 Gilberto Comiran.pdf: 1846926 bytes, checksum: 1b96f9d3924516f3c3a1814a89cd0014 (MD5) Previous issue date: 2006-07-21 / In this work, it is shown an application of a model to obtain the hydraulic conductivity of soils no saturated using concepts Fractal Geometry and the laws of Laplace and of Poiseuille. For the obtaining of the soil water retention curve it was used the camera of pressure of Richards and the experimental data of hydraulic conductivity in function of the soil water content were obtained through the Method of Hillel with the tensiometry use, according to a potency model. The equation van Genuchten with their parameters was used for the obtaining of the hydraulic conductivity. The application of the models of the Geometric Average and of the Neutral Pore suggested by Fuentes was shown simple and capable of predicting the hydraulic conductivity satisfactorily. / Neste trabalho, apresenta-se a aplicação de um modelo para se estimar a condutividade hidráulica de solos não saturados, utilizando os conceitos da Geometria Fractal e das leis de Laplace e de Poiseuille. Para a obtenção da curva de retenção de água, foi utilizada a câmara de pressão de Richards e os dados experimentais de condutividade hidráulica, em função da umidade do solo, foram obtidos através do Método de Hillel com a utilização de tensiometria, conforme um modelo de potência. A equação de van Genuchten, com seus parâmetros, foi utilizada para a obtenção da condutividade hidráulica. A aplicação dos modelos da Média Geométrica e do Poro Neutro sugerido por Fuentes mostrou-se simples e capaz de predizer a condutividade hidráulica satisfatoriamente.

Functional coatings produced using scalable and cost-effective processes such as electrodeposition and etching lead to the creation of random roughness at multiple length scales on the surface. The first part of thesis work aims at developing a fundamental mathematical understanding of multiscale coatings by presenting a fractal model to describe wettability on such surfaces. These surfaces are described with a fractal asperity model based on the Weierstrass-Mandelbrot function. Using this description, a model is presented to evaluate the apparent contact angle in different wetting regimes. Experimental validation of the model predictions is presented on various hydrophobic and superhydrophobic surfaces generated on several materials under different processing conditions. Superhydrophobic surfaces have myriad industrial applications, yet their practical utilization has been severely limited by their poor mechanical durability and longevity. Toward addressing this gap, the second and third parts of this thesis work present low cost, facile processes to fabricate superhydrophobic copper and zinc-based coatings via electrodeposition. Additionally, systematic studies are presented on coatings fabricated under different processing conditions to demonstrate excellent durability, mechanical and underwater stability, and corrosion resistance. The presented processes can be scaled to larger, durable coatings with controllable wettability for diverse applications. Apart from their use as superhydrophobic surfaces, the application of multiscale coatings in photo-thermal conversion systems as solar selective coatings is explored in the final part of this thesis. The effects of scale-independent fractal parameters of the coating surfaces and heat treatment are systematically explored with respect to their optical properties of absorptance, emittance, and figure of merit (FOM). / Master of Science / Coatings are extensively used through various industries and serve a range of purposes such as providing protection, changing the physical and chemical properties, decoration, and adding other new properties to the base surface. Coatings produced using scalable and cost-effective processes such as electrodeposition and etching are inherently rough and have features ranging from micro- to nano-scale, leading to their multiscale nature. The first part of thesis work aims at developing a fundamental mathematical understanding of these rough coatings by presenting a model to describe and predict the wettability on such surfaces. Wettability of a surface is its ability to maintain contact with a liquid, resulting from intermolecular interactions when the two are brought together. Wettability for a solid surface is generally quantified by the contact angle, measured through the liquid, where a liquid-vapor interface meets the solid surface. A mathematical model is presented to evaluate the apparent contact angle on such multiscale rough surfaces. Experimental validation of the model predictions is presented on various hydrophobic and superhydrophobic surfaces generated on several materials under different processing conditions. Superhydrophobic surfaces do not get wet by water and water droplet contact angle on these surfaces exceed 150°. Such surfaces have extensive industrial applications, yet their practical utilization has been severely limited by their poor mechanical durability and longevity. Toward addressing this gap, the second and third parts of this thesis work present low cost, facile processes to fabricate superhydrophobic copper and zinc-based coatings via electrodeposition. Additionally, systematic studies are presented on coatings fabricated under different processing conditions to demonstrate excellent durability, mechanical and underwater stability, and corrosion resistance. The presented processes can be scaled to larger, durable coatings with controllable wettability for diverse applications. Apart from their use as superhydrophobic surfaces, the application of multiscale coatings in photo-thermal conversion systems as solar selective coatings is explored in the final part of this iv thesis. Solar selective coatings aim to improve photo-thermal conversion efficiency by providing a high solar absorptance and low thermal emittance. Solar selective coatings ensure that maximum incoming solar radiation is absorbed into the surface and radiative losses due to emissions at high temperatures are minimized. The effects of scale-independent mathematical parameters of the coating surfaces and heat treatment are systematically explored with respect to their optical properties of absorptance, emittance, and figure of merit (FOM).