Au cours de ce travail, nous avons décrit et mis en œuvre la fabrication de surfaces nanostructurées d’alumine par anodisation de feuilles d’aluminium de très grande pureté. Les paramètres morphologiques caractérisant la membrane d’oxyde que sont le diamètre des pores, leur profondeur et leur espacement sont finement contrôlés par les paramètres expérimentaux. Ces surfaces nanotexturées ont permis l’étude approfondie de l’interaction solide-liquide au sein des pores et de la physique de la ligne de contact devant composer avec les nano-aspérités de surface. Ces deux éléments ont pu être appréhendés par des mesures d’angles de contact à l’équilibre et d’hystérésis de mouillage. La modélisation des résultats a montré l’inadéquation des modèles classiques de CASSIE, WENZEL ou de capillarité à cette situation. L’adjonction du terme controversé de tension de ligne permet de bonnes prévisions. Nous montrons que cette interprétation n’est pas unique ; une diminution de l’énergie de surface due à la forte courbure des pores conduit à des résultats identiques. Une investigation théorique a été menée par l’intégration des forces de VAN DER WAALS. La baisse de l’énergie de surface est prévue mais dans des proportions insuffisantes. Le modèle peut être amélioré. Les mesures d’hystérésis ont dévoilé le pouvoir adhésif des surfaces nanoporeuses. À cause des forces de capillarité dans les pores, la ligne de contact ne peut jamais reculer. Les angles d’avancée ont montré que la ligne de contact a une épaisseur négligeable devant la dizaine de nanomètre. Elle peut en outre parfaitement contourner les pores, imprimant de fortes courbures à l’interface liquide-gaz à la base de la goutte. Sa forme tridimensionnelle a été abordée au travers d’un modèle numérique restant à perfectionner. / In this work, we have described and carried out the fabrication of nanostructured alumina surfaces by anodizing highly pure aluminum foils. The pore diameter, depth and spacing are finely controled through experimental parameters. These nanotextured surfaces allowed a thorough study of the solid-liquid interactions within the pores and of the contact-line constrained by the surface nanoasperities. Equilibrium contact-angle and wetting hysteresis measurements were helpful to apprehend them. Modeling the results has revealed the inability of classical CASSIE, WENZEL and capillarity models to properly match the situation. Adding the controversial line-tension term solves the problem and provides good predictions. Anyway, this interpretation is not unique. A lower surface energy within the pores due to their strong curvature yields the same modeling quality. This case has been theoretically investigated through the integration of VAN DER WAALS’ forces. A surface-energy decrease has been calculated but it is not as strong as required. The model still can be improved. Hysteresis measurements have highlighted the nanoporous surfaces are strongly adhesive. Because of the pore size, the capillarity is very marked and keeps the contact line from receding. The advancing contact angles have shown that the contact-line thickness is negligible with respect of ten nanometres. In addition, it can circumvent the pore openings which involves strong liquid–gas interface curvatures at the drop base. The three-dimensional liquid–gas interface shape has been studied with a numerical model that still has to be enhanced.

In an effort to make structures more sustainable and durable, supplementary cementitious materials are often used to replace cement. Ground granulated blast furnace slag, for instance, is an industrial by-product of iron refinement and is frequently used in concrete mixture design to not only reduce cost, but also increase later-age strength as well as durability. However, published literature indicates that slags with a high alumina content may have a detrimental effect when concrete is exposed to a sulfate environment. ASTM standard C989 does not suggest any information or guidelines regarding using slags with an alumina content between 11-18%. Therefore, the objective of this study was to fill in the gap of this standard by studying slags of variable alumina content as high as 16 percent. This study presents data collected for compressive strengths of mortar cubes exposed to lime and 5 percent sodium sulfate solution at ages of 7, 28, 91, and 182 days from the date of mixing as well as expansion data for mortar bar specimens exposed to 5 percent sodium sulfate solution up to 120 days. Slag replacement levels used here were 0, 30, 50, and 70%. Mortar bar specimens showing deterioration were analyzed using x-ray diffraction coupled with Rietveld refinement to assess the mechanism of deterioration. Cubes were stored in lime and sulfate solutions abiding by ASTM C1012 in order to analyze the resistance to sulfate attack. Sulfate resistance was measured in terms of decalcification of the CSH gel as well as expansion. The results suggest using high alumina slags at a low percentage adversely affects sulfate resistance since the acquired strength at 182 days fell below that of 28 day strength, which is often used in the industry as the parameter which constitutes whether a mixture is adequate. It was also seen that increasing alumina content of the slag resulted in increased expansion. X-ray diffraction analysis indicates that the mechanism of deterioration, of the control as well as the blended mortar, is due to secondary gypsum and secondary ettringite formation. Therefore, it is recommended that slags having a high alumina content should be further analyzed in laboratory tests to examine their performance especially if concrete will be subjected to a sulfate environment during its service life.

L’élaboration des céramiques nanocomposites s’impose dans l’actualité comme une des voies la plus prometteuse pour l’obtention des matériaux céramiques ayant des propriétés remarquables. Toutefois, il s’agit d’une voie compliquée puisque la nanostructure et la densification des matériaux sont en général contradictoires. En effet, les relativement hautes températures et longues périodes de temps requises pour bien densifier les matériaux céramiques nanocomposites produisent le phénomène de grossissement des grains : dans ces conditions les phases présentes dans le composite cessent d’être nanostructurées. Dans ce contexte, l’utilisation de nouvelles techniques de frittage, telles que le « Spark Plasma Sintering » (SPS), peuvent aider à la consolidation de ce type de matériaux tout en conservant une microstructure fine. Ce travail de recherche a été consacré à l’élaboration des micro-nanocomposites alumine/5vol% SiC en utilisant trois techniques de frittage : conventionnelle ou naturelle (FN), le pressage à chaud (« Hot Pressing » ou HP) et principalement le frittage par « Spark Plasma Sintering ». Dans un premier temps, l’étape de dispersion des poudres d’alumine et de SiC a été optimisée afin de préparer des barbotines stables et homogènes et des poudres composites. Puis, les meilleures performances de la technique SPS par rapport aux autres techniques de frittage ont été mises en évidence. Ainsi, l’utilisation du frittage SPS permet une meilleure maîtrise de la microstructure : densité élevée, microstructure fine et la localisation des particules nanométriques principalement en position intergranulaire. / The development of ceramic nanocomposites is needed in the news as one of the most promising ways to obtain ceramic materials with remarkable properties. However, this is a complicated way since the nanostructure materials and densification are usually contradictory. Indeed, the relatively high temperatures and long periods of time required to fully densify the ceramic nanocomposite materials produce the phenomenon of grain growth: in these conditions the phases present in the composite cease to be nanostructured. In this context, the use of new sintering techniques, such as "Spark Plasma Sintering" (SPS), may help to consolidate this type of material while maintaining a fine microstructure. This research has been devoted to developing micro-SiC nanocomposites alumine/5vol% using three sintering techniques: conventional or natural (FN), hot pressing ("Hot Dry" or HP) and mainly the sintering by "Spark Plasma Sintering." As a first step, the step of dispersing powders of alumina and SiC was optimized to prepare stable and homogeneous slurry and composite powders. Then, the best performances of the technique compared to other SPS sintering techniques have been demonstrated. Thus, the use of SPS sintering allows better control of the microstructure: high density, fine microstructure and localization of nanoparticles mainly intergranular position.

Les zéolithes sont des aluminosilicates cristallins possédant une microporosité organisée et régulière de taille moléculaire. Les zéolithes ZSM-5 sont largement employées dans l’industrie comme catalyseurs acides mais leur application commerciale requiert des objets de taille millimétrique pour leur résistance mécanique, pour diminuer la perte de charge dans les réacteurs et pour diluer l’acidité de la zéolithe, principalement par ajout de liant, peptisant... La mise en forme est l’étape clé dans le processus d’industrialisation d’un catalyseur car les additifs peuvent modifier les propriétés intrinsèques de la zéolithe après mise en forme. Les objectifs de la thèse sont donc d’identifier et de rationaliser les conséquences physico-chimiques de la mise en forme sur les propriétés des zéolithes en étudiant l’accessibilité, la concentration et la force de leurs sites acides, ainsi que de décrire la nature de l’interface zéolithe/liant. Pour cela, une approche multi-techniques a été mise en œuvre. Elle combine des mises en forme modèles, tout en faisant varier la nature du liant et de la zéolithe ZSM-5, des caractérisations texturales, spectroscopiques (infra-rouge, RMN) et de microscopies, de l’acidité (adsorption-désorption de molécules sondes suivies par analyses thermiques et spectroscopiques), et tests catalytiques modèles. La caractérisation des propriétés des zéolithes utilisées dans cette étude (de différentes tailles de cristaux et de différents rapports Si/Al) a été menée préalablement à celles des matériaux mis en forme. Les grands cristaux de zéolithes se sont révélés plus acides mais moins actifs en catalyse. Une partie des Al des petits cristaux forment des aluminols dont l’acidité est plus faible que celle des sites pontés. De plus, l’ensemble des sites pontés ne contribue pas à la réaction catalytique, seule une partie du cristal est efficace. Durant ce travail, deux types de liants ont été utilisés : l’alumine et la silice qui sont largement employées dans l’industrie. Le but a été de mettre en évidence, dans un premier temps, les effets de la mise en forme sur une zéolithe et un liant donné puis d’estimer l’impact de la nature de la zéolithe (taille de cristal et rapport Si/Al). Pour le liant de type alumine, un bouchage partiel de la microporosité est suspecté indépendamment de la taille des cristaux et du rapport Si/Al de la zéolithe. Un phénomène d’alumination de la structure de la zéolithe par création de sites pontés a été mis en évidence. Pour le liant de type silice, le paramètre critique à prendre en considération lors de la mise en forme est sa teneur en cations sodium. Le phénomène d’échange ionique a été mis en évidence, les propriétés acides et catalytiques des catalyseurs s’effondrent mais de manière réversible. Cet effet augmente quand la taille des cristaux de zéolithes diminue et quand le rapport Si/Al augmente / Zeolites are crystalline and microporous aluminosilicates with an ordered and regular structure of molecular dimension. ZSM-5 zeolites are widely used in the industry as acid catalysts but their commercial application requires millimeter-sized bodies for mechanical strength and dilution of the zeolite acidity mainly, by addition of binder, peptizer... Shaping of zeolite is the key step of the process for the industrialization of a catalyst because the additives may modify the intrinsic properties of zeolites after shaping. The aims of this PhD thesis are to identify and rationalize the physico-chemical impacts of shaping on the zeolite properties by studying the accessibility, the concentration and the strength of acid sites, as well as to describe the zeolite/binder interface. To do this, a multi-technical approach was set up. It combines model shaped materials, by varying the type of binder and ZSM-5 zeolite, textural, spectroscopic (IR, NMR) and acid characterizations, microscopy and catalytic testing. The characterization of zeolites used in this study (various crystal sizes and Si/Al ratios) was carried out prior of those of shaped materials. Large crystals have been shown more acid but less active in catalysis. Some of Al of the small crystals form aluminols whose acidity is weaker than that of bridging sites. Moreover, all the bridging sites do not contribute to the catalytic reaction, only a part of the crystal is efficient. During this work, two types of binders were used: alumina and silica which are widely used in the industry. The strategy was to highlight, in a first step, the shaping impacts on a ZSM-5 and a given binder and then, to estimate the impact of the zeolite nature (crystal size and Si/Al ratio). For the alumina-type binder, a partial pore blocking is suspected, independently of the crystal size and the Si/Al ratios. A phenomenon of alumination of the zeolite structure was found. For the silica-type binder, the critical parameter is the content of sodium cations inside the binder before the shaping. An ion exchange phenomenon was highlighted and the acid and catalytic properties of the materials collapse but in a reversible way. This impact increases when the crystal size decreases and when the Si/Al ratio increases

The desire of the minerals industry to be more sustainable has led towards the increasing development of by-products. One such industry is the production of Alumina. The Alumina industry in Australia is the major producer of alumina in the western world with over 25 million tonnes of Bauxite Residue per annum. Alcoa World Alumina (Alcoa) has three refineries in Western Australia producing approximately 20,000 tonnes of Mud and a similar level of Red Sand each day. These as yet unutilised potential resources are being stockpiled, occupying a significant footprint. It is widely recognised within industry that there would be economic, environment and social benefits if a sustainable use for these materials were found. One such potential by-product is the production of coarse bauxite residue (Red Sand), neutralised and washed low in salt. The main purpose of this research was to establish a potential market for this material, through scientific evaluation of Red Sand as a replacement of natural fine aggregate (Natural Yellow Sand) in concrete mixes. For this research, the mixed stream of Bauxite Residue (fine and coarse) obtained in the Bayer process was neutralized by a process of carbonation then washed using cyclones and counter current wash towers to a value added byproduct. The coarse particles (Washed and Carbonated Sand-WCS) of the stream were separated by Wet High Intensity Magnetic Separation technique (WHIMS) so that different segments such as High Iron Sand (HIS) and Low Iron Sand (LIS) were formed. Physical, chemical and mineralogical properties of these materials have been tested and compared with that of natural sand. Several mixes of concrete were then designed using Red Sand as a fine aggregate in order to verify their effects on strength and durability indicators of concrete. / The comparative analysis between normal mix proportions and the mix proportions utilizing Red Sand was also achieved. In addition, the impact of marine environment on concrete mix design and properties of manufactured concrete were evaluated with a series of standard laboratory tests. The findings were promising in terms of both mechanical properties and durability and suggested that Red Sand, in particular Low Iron Sand is likely to be effective in place of fine aggregates and can be used within marine grade concrete with no major differences when compared to normal concrete. From the results obtained, it can be deduced that this material can be used in a wide range of concrete applications in Civil Engineering and Construction.

Differential geometric nonlinear control of a multiple stage evaporator system of the liquor burning facility associated with the Bayer process for alumina production at Alcoa Wagerup alumina refinery, Western Australia was investigated.Mathematical models for differential geometric analysis and nonlinear controller synthesis for the evaporator system were developed. Two models, that were structurally different from each other, were used in the thesis for simulation studies. Geometric nonlinear control structure, consisting of nonlinear state feedback control laws and multi-loop single-input single-output proportional-integral controllers, were designed for the industrial evaporator system. The superiority of the geometric nonlinear control structure for regulatory control of the evaporator system was successfully demonstrated through computer simulations and real-time simulator implementation. The implementation trial has verified the practicality and feasibility of these type of controllers. It also re-solved some practical issues of the geometric nonlinear control structure for industrial control applications. In addition, the implementation trial also established a closer link between the academic nonlinear control theory and the industrial control practices.Geometric nonlinear output feedback controller, consisting of the geometric nonlinear control structure and reduce-order observer was proposed for actual plant implementation on the evaporator system on-site. Its superior performance was verified through computer simulations, but its feasibility on the evaporator system on-site has yet to be investigated either through simulator implementation or actual plant implementation. This investigation was not performed due to the time constraint on the preparation of this thesis and the inavailability of the plant personnel required for this implementation.Robust ++ / nonlinear control structures that are simple and computationally efficient have been proposed for enhancing the performance of geometric nonlinear controllers in the presence of plant/model mismatch and/or external disturbances. The robust nonlinear control structures are based on model error compensation methods. Robustness properties of the proposed robust nonlinear control structures on the evaporator system were investigated through computer simulations and the results indicated improved performance over the implemented geometric nonlinear controller in terms of model uncertainty and disturbance reductions.A software package was developed in MAPLE computing environment for the analysis of nonlinear processes and the design of geometric nonlinear controllers. This developed symbolic package is useful for obtaining fast and exact solutions for the analysis and design of nonlinear control systems. Procedures were also developed to simulate the geometric nonlinear control systems. It was found that MAPLE, while it is superior for the analyses and designs, is not viable for simulations of nonlinear control systems. This was due to limitation of MAPLE on the physical, or virtual, memory management. The use of both symbolic and numeric computation for solutions of nonlinear control system analysis, design and simulation is recommended.To sum up, geometric nonlinear controllers have been designed for an industrial multiple stage evaporator system and their simplicity, practicality, feasibility and superiority for industrial control practices have been demonstrated either through computer simulations or real-time implementation. It is hoped that the insights provided in this thesis will encourage more industry-based projects in nonlinear control, and thereby assist in closing the widening gap between academic nonlinear control theory and industrial control ++ / practice.Keywords: geometric nonlinear control, input-output linearization, multiple stage evaporator, robust geometric nonlinear control, control performance enhancement.

Biologically inspired materials are being developed with the aim of improving the integration of medical implants and minimizing non-desirable host reactions. A promising strategy is the design of topographically patterned surfaces that resemble those found in the extracellular environment. Nanoporous alumina has been recognized as a potential biomaterial and as an important template for the fabrication of nanostructures. In this thesis in vitro studies were done to elucidate the role of alumina nanoporosity on the inflammatory response. Specifically, by comparing alumina membranes with two pore sizes (20 and 200 nm in diameter). Complement and platelet activation were evaluated as well as monocyte/macrophage behaviour. Whole blood was incubated with the alumina membranes and thereafter the biomaterial surfaces were evaluated in terms of protein and platelet adhesion as well as procoagulant properties. The fluid phase was analyzed for complement activation products and platelet activation markers. Besides, human mononuclear cells were cultured on the alumina membranes and cell adhesion, viability, morphology and release of pro-inflammatory cytokines were evaluated. The results indicated that nanoporous alumina with 200 nm pores promotes higher complement activation than alumina with 20 nm pores. In addition, platelet response to nanoporous alumina was found to be highly dependent on the material porosity, as reflected by differences in adhesion, PMP generation and procoagulant characteristics. A clear difference in monocyte/macrophage adhesion and activation was found between the two pore size alumina membranes. Few but highly activated cells adhered to the 200 nm membrane in contrast to many but less activated monocytes/macrophages on the 20 nm surface. The outcome of this work emphasizes that nanotopography plays an important role in the host response to biomaterials. Better understanding of molecular interactions on nano-level will undoubtedly play a significant role in biomaterial implant development and will contribute to design strategies for controlling specific biological events.

Multi-walled carbon nanotubes (MWCNTs) are a potential alternative to commonly used catalyst support structures in hydrotreating processes. Synthesis of MWCNTs with specific pore diameters can be achieved by chemical vapor deposition (CVD) of a carbon source onto an anodic aluminum oxide (AAO) template. AAO films consist of pore channels in a uniform hexagonal arrangement that run parallel to the surface of the film. These films are created by the passivation of an aluminum anode within an electrolysis cell consisting of certain weak acid electrolytes. Changing the concentration of the electrolyte (oxalic acid) and the electrical potential of the electrolysis cell altered the pore channel diameter of these AAO films. Controlling the pore diameter of these templates enabled the pore diameter of MWCNTs synthesized by CVD to be controlled as well. The produced MWCNTs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Raman spectroscopy, and N2 adsorption analysis. Anodizing conditions of 0.40 M oxalic acid concentration and 40.0 V maximum anodizing potential were found to produce AAO films that resulted in MWCNTs with optimum surface characteristics for a catalyst support application. CVD parameter values of 650°C reaction temperature and 8.00 mL/(min·g) C2H2-to-AAO ratio were found to produce the highest yield of MWCNT product.<p> The MWCNTs were synthesized for the purpose of supporting hydroprocessing catalysts, with several grades of NiMo/MWCNT sulfide catalysts being prepared to determine the optimum pore size. These catalysts were characterized by techniques of TEM, CO chemisorption, N2 adsorption, and H2 temperature programmed reduction (TPR). A MWCNT grade with 67 nm inner diameters (found from TEM analysis) was found to offer the best hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities for the treatment of coker light gas oil (CLGO). After determining the most suitable pore diameter, the optimum catalyst metal loadings were found to be 2.5 wt.% for Ni and 19.5 wt.% for Mo. The optimum catalyst was found to offer HDS conversions of 90.5%, 84.4%, and 73.5% with HDN conversions of 75.9%, 65.8%, and 55.3% for temperatures of 370°C, 350°C, and 330°C, respectively. An equal mass loading of commercial NiMo/ã-Al2O3 catalyst offered HDS conversions of 91.2%, 77.9%, and 58.5% with HDN conversions of 71.4%, 53.2%, and 31.3% for temperatures of 370°C, 350°C, and 330°C, respectively.<p> A kinetic study was performed on the optimum NiMo/MWCNT catalyst to help predict its HDS and HDN activities while varying the parameters of temperature, liquid hourly space velocity (LHSV), pressure, and gas-to-oil flow rate ratio. Rate expressions were then developed to predict the behavior of both the HDS and HDN reactions. Power law models were best fit with reaction orders of 2.6 and 1.2, and activation energies of 161 kJ/mol and 82.3 kJ/mol, for the HDS and HDN reactions, respectively. Generalized Langmuir-Hinshelwood models were found to have reaction orders of 3.0 and 1.5, and activation energies of 155 kJ/mol and 42.3 kJ/mol, for the HDS and HDN reactions, respectively.

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