Дисертації з теми "[669.017"

Дисертація присвячена вирішенню науково-технічної задачі з розробки нових багатокомпонентних сплавів, які мають поліпшені властивості. Вивчено вплив концентрації вихідних елементів на фазовий склад, мікроструктуру та фізико-механічні властивості сплавів системи Сr-Ni-Co-Fe-Cu-Al. Розроблено шестикомпонентний сплав CrMnFeCoNi2Cu з високими показниками деформованості. Досліджено вплив деформації цього сплаву на фазовий склад, текстуру, мікроструктуру, фізико-механічні властивості та показано високу термічну стабільність цих показників. Визначено умови утворення -фази в багатокомпонентних сплавах. На їх основі розроблено систему сплавів, які містять -фазу, досліджено фазовий склад, мікроструктуру, фізико-механічні властивості та зносостійкість.
Dissertation is devoted to the solution of scientific and technical problem on finding of the new multicomponent alloys, having dipped properties. The features of the structure and properties of high-entropy alloys of Cr-Al-Fe-Co- Ni-Cu-Mn-V. The effect of additional doping on their phase composition, microstructure and physical and mechanical properties. Developed six component alloy CrMnFeCoNi2Cu with high deformability. The influence of strain on alloy phase composition, texture, microstructure, physical and mechanical properties and high thermal stability shown in these figures. The conditions of formation of -phase multicomponent alloys. Based on these conditions, the system of alloys containing -phase studied their phase composition, microstructure, physical and mechanical properties and wear resistance.
Диссертация посвящена решению научно-технической задачи по разработке высокоэнтропийных сплавов с улучшенными свойствами. Сплавы получены аргонно-дуговой плавкой и исследованы рентгеноструктурным анализом, растровой электронной микроскопией с локальным рентгеноспектральным анализом, оптической микроскопией, энергодисперсионным рентгенофлуоресцентным анализом, микроиндентированием. Были проведены испытания на износостойкость согласно ГОСТ 23.208-79. В работе впервые систематически исследовано и определено влияние содержания элементов на сплавы системы Cr-Al-Fe-Co-Ni-Cu. Исследованы фазовый состав, микроструктура, физико-механические свойства и распределение элементов между структурными составляющими. Все сплавы, данной системы, характеризуются высокой твердостью, которая не присущая ни одному из исходных компонентов. Показано, что во всем исследованном концентрационном интервале изменения содержания элементов, вследствие высокой энтропии смешения, образуются только фазы на основе неупорядоченных твердых растворов замещения с ОЦК- и ГЦК-структурами, а также твердый раствор на основе фазы упорядоченной по типу В2. Показано, что в данной системе тип кристаллической решётки твердого раствора определяется средней электронной концентрацией исходных компонентов. Элементы, повышающие среднюю электронную концентрацию (Cu, Ni, Co), способствуют образованию твердого раствора на основе фазы с ГЦК-структурой, понижающие (Al, Cr) – твердого раствора на основе фазы с ОЦК-структурой. Элементы, не влияющие на среднюю электронную концентрацию (Fe), к его однофазному состоянию не приводят. Разработан сплав CrMnFeCoNi2Cu способен деформироваться холодной прокаткой на большие степени деформации без появления трещин или надрывов. Деформация осуществлялась путем последовательной прокатки на станах ДУО-500, ДУО-300, и КВАРТО-100, при комнатной температуре. Показано, что при деформации возрастает его микротвердость, а модуль Юнга остается постоянным после деформации на 70 %. Фазовый состав сплава в литом состоянии состоит из двух твердых растворов на основе фаз с ГЦК-структурами. По мере увеличения степени деформации количество твердого раствора на основе фазы с ГЦК1- структурой уменьшается. Холодная прокатка разработанного сплава приводит к изменению текстуры литья в текстуру прокатки, которая подобна к текстуре прокатки ГЦК-металлов и сплавов. Проведенные отжиги показали высокую термическую стабильность фазового состава, структуры и физико-механических свойств. Так, микротвердость и модуль Юнга сплава деформированного на 98 %, снизились до показателей в литом состоянии только после двухчасового отжига при Т= 1473 К, что составляет (0,97 Тплавл). Отжиг данного сплава в литом и деформированном на 80 % состоянии, при температуре 1073 К и выше, способствует гомогенизации и образованию одного твердого раствора на основе фазы с ГЦК-структурой вместо двух. Отжиг свыше 1273 К, сплава деформированного на 98 %, приводит к выделению по границам зерен ГЦК1 фазовой составляющей. Изменение микротвердости от среднего размера зерен подчиняется соотношению Холла-Петча. Определены условия формирования многокомпонентной -фазы типа (FeCr) в системе V-Сr-Mn-Fe-Co-Ni. Получены сплавы данной системы, исследованы их фазовый состав, микроструктура и физико-механические свойства. Определена износостойкость сплавов VСrMnFeCoNi2, VСrMnFeCoNi1,5, VСrMnFeCoNi при трении об нежестко закрепленные абразивные частицы. Показано, что износостойкость сплава VСrMnFeCoNi близка к промышленному наплавочному материалу Т-590.

This project investigated the feasibility of derivatizing a montmorillonitic clay, with commercial liquid extractants to obtain a material with the metal extraction properties of the liquid extractant that can be applied directly into metal leaching circuits. The intercalation of several commercial liquid-liquid extractants: alkylphosphoric acid (DEHP A), carboxylic acid (Versatic 1 0), l3-hydroxyoxime (Acorga M-5640), substituted hydroxyquinoline (Kelex 100) and l3-diketone (LIX 54) was carried out. The alkylphosphoric extractant, DEHPA, was taken as a model for obtaining data on parameters that influence the adsorption of the molecule onto the clay. The variables studied were the kinetics of adsorption, effect of composition of the selected solvent media (EtOHIH20) and interlayer cations both inorganic (Na+, Ca2+ and Cu2+) and organic (alkylammonium). Optimum conditions obtained for the alkylphosphoric extractant were then applied to the other extractants. X-ray powder diffraction and FTIR characterisation confirmed that the extractant molecule was adsorbed in the interlayer spaces of the clay. The adsorption process showed fast kinetics (five to fifteen minutes), was strongly related to the water content of the solvent media and to the nature of the interlayer cation. The mechanisms for the adsorption of the extractant on the homoionic inorganic and organic clays are discussed. All the intercalated materials extract copper and nickel ions from solution and the metal loadings are similar to materials such as Solvent Impregnated Resins (SIR). The loading isotherms and maximum loading capacities indicate the formation of both 2: 1 and the charged 1: 1 extractant:metal complexes. Extractant losses from the alkylphosphoric intercalated montmorillonites during use compare very favourably with similar liquid-liquid systems or SIR's containing the same extractant. Attempts to agglomerate the resulting intercalated material to obtain pellets between 1 and 2 mm in diameter were made using different inorganic and organic polymeric binders. The most effective binder was a crosslinked polyester obtained by in-situ polymerisation on the clay. The resulting clay-extractant pellets retained their metal extraction properties with acceptable mechanical properties, but the process requires further optimisation.

Selective laser melting (SLM) is an additive manufacturing technique to produce complex three-dimensional parts through solidifying successive layers of powder materials on top of each other, from the bottom to top. The powder base nature allows the SLM to process a wide variety of materials and their mixtures and fabricate advanced and complicated composite parts. However, the SLM is a newly established process and seeks detailed scientific studies to develop new materials systems for the consumption of industry. These scientific studies are particularly important because of many issues associated with the SLM process, such as porosity, balling, delamination, thermal stress, etc, which can be varied from one material system to another. This PhD project aims to elucidate the fundamental mechanisms governing the microstructure and mechanical properties of the metallic and in-situ Al matrix composite parts made by SLM. The research starts with a preliminary study on SLM of stainless steel in order to explore the usage of SLM machine and related parameters. It illustrates the effect of part layout on the quality of products. The main research focuses on the in-situ formation of particulate reinforced Al matrix by using SLM of Al/Fe2O3 powder mixture. It is a pioneering research to integrate in-situ interaction with laser melting to produce advanced Al composites. It investigates the mechanisms governing SLM assisted in-situ reaction and also the effects of various parameters such as SLM layer thickness, laser power and scanning speed as well as the proportion of Fe2O3. It examines the influence of Al alloy powder and it describes the effect of hot isostatic pressing (HIP) post-treatment. The physical, mechanical, and metallurgical properties of the products are extensively assessed using various techniques. The processing windows of the process are sketched. The findings demonstrate unique microstructural features due to combined in-situ reaction and laser rapid consolidation, and contribute to provision of an in-depth scientific understanding of novel Al matrix composites by using SLM assisted in-situ processes. As part of this PhD project, industrial collaborative research has also been conducted to characterise the surface finish, metallurgical quality, process accuracy and mechanical properties of various SLM made metallic parts using Al, Ti, stainless steel, and super alloys. This part of research has generated scientific data and results for industrial applications of metallic fabrication using SLM.

This thesis involves the design and development of reagents for the recovery of base metals (specifically zinc, nickel and cobalt) in hydrometallurgical solvent extraction processes. The work aims to demonstrate how ligand design can affectively tune the strength and selectivity of extractants to achieve efficient recovery of the desired base metals. Chapter 1 reviews current solvent extraction processes used in extractive metallurgy, encompassing both the well established technologies developed for sulfate streams as well as those more recently explored for treating chloride streams. Also reviewed, is the nature of the chemical binding involved in the three key modes of extraction; namely cation transport, anion transport and metal salt transport. Chapter 2 summarises the methodologies that have been established during this research for the appropriate testing of these reagents. Chapter 3 deals exclusively with the processing of zinc sulfide ores with an aim to design reagents to achieve concentration and separation of zinc in chloride hydrometallurgical circuits. The amido functionalised reagents that are reported have a common structural feature with ligands that have been previously studied by the Tasker group (Ross J. Ellis Thesis, University of Edinburgh, 2009). A six membered chelate ring is formed by a protonated amino nitrogen atom and an amido oxygen atom in a sequence of the type R2HN+-CH2-NR-CO-R. This differs from those previously studied which have a sequence of the type R2HN+-CH2-CHR-CO-NR2. The pro-ligands (L) operate via an anion exchange mechanism (Equation 1) whereby two protonated ligands (LH+) coordinate to the outersphere of anionic zinc(II) or iron(III) chloridometalates from acid chloride solutions using both N-H and C-H hydrogen-bond donors. pH dependent solvent extraction experiments have concluded that this reagent series achieves zinc(II) loading with pH0.5 values that are competitive with the previous ligand series (Ross J. Ellis Thesis, University of Edinburgh, 2009). Chloride concentration dependent solvent extraction experiments have demonstrated that the reagents show an unusually good selectivity for ZnCl4 2- over chloride or FeCl4 - in equilibrium of the type; yLorg + yH+ +MClx y- ⇌ [(LH)yMClx](org) (1) The development of bidentate and tridentate pyrazolone-based pro-ligands for the extraction of nickel and cobalt from mixed metal sulfate streams is considered in Chapters 4 and 5. These reagents (LH) operate via metal cation transport, where an inner-sphere complex of nickel(II) or cobalt(II) is formed with the ligand (L-) see Equation 2. A combination of N, O and S donors has been incorporated into 1-phenyl-3-methyl-4- acylpyrazol-5-ones and their respective 4-acylpyrazolone oximes in order to tune the bidentate ligands (L-) for optimal coordination with nickel(II) or cobalt(II). Substituent effects have also been investigated, by synthesising a series of 1-(2-X-phenyl)-3-methyl-4- acylpyrazol-5-one oximes [X = Cl, H]. Substitution in the 3-position of the phenol group in phenolic oximes has been reported to increase extractant strength for copper by two orders of magnitude (Ross S. Forgan Thesis, University of Edinburgh, 2008). Similar improvements were not observed in this study. The nature of this effect has been attributed to buttressing of hydrogen-bonds, where the substituent forms a stabilising, bifurcated hydrogen-bond between the oximic hydrogen and the pyrazolonic oxygen. yLHorg + My+ ⇌ [(L)yM]org + yH+ (2) Tridentate analogues of the oxime reagents above have been prepared as imines derived from anilines contained o-O, S or N donor atoms. It was hoped that these would give high spin octahedral nickel(II) complexes in extraction processes. They proved to be weak extractants. Chapter 6 focuses of the development of bidentate pyrazolethiones for the selective extraction of cobalt from manganese in acidic sulfate streams. These reagents have been designed to favour coordination to metals in a tetrahedral geometry as shown by L. Emeleus and A. Smith for copper and zinc (Lucy Emeleus Thesis, University of Edinburgh 1999 and Andrew Smith Thesis, University of Edinburgh 2000).

Les nanoparticules de platine (Pt) représentent environ la moitié du coût de fabrication des piles à combustible à membrane échangeuses de protons (PEMFC), ce qui constitue un frein à leur commercialisation à grande échelle. La récupération du Pt contenu dans les piles usagées apparaît donc nécessaire. Les voies de traitement habituellement mises en œuvre pour le recyclage de catalyseurs à base de Pt sont des procédés pyro-hydrométallurgiques, générateurs d’émissions polluantes (CO2, NO2). Une voie de traitement électrochimique en milieu liquide ionique (LI), plus respectueuse de l'environnement, est proposée ici. Elle combine dans une seule cellule la lixiviation du Pt par dissolution anodique et sa récupération par électrodéposition, dans des conditions de température "douces", sans émission de gaz nocifs. L’étude de nombreux électrolytes a permis de sélectionner les mélanges BMIMTFSI + BMIMCl (bis(trifluorométhylsulfonyl) imidure + chlorure de 1-butyl-3-méthylimidazolium), en raison du caractère complexant des chlorures facilitant la lixiviation du Pt et de la bonne stabilité électrochimique du BMIMTFSI. L’anion TFSI-, peu coordonnant, permet de moduler le caractère complexant de l’électrolyte, paramètre clé du procédé influant sur la nature et la stabilité électrochimique du complexe de Pt formé par lixiviation. Au cours de ce travail, les conditions expérimentales permettant de lixivier et d’électrodéposer le Pt dans une cellule unitaire ont été définies et appliquées avec succès aux électrodes de PEMFC. L’électrolyte sélectionné, faiblement hygroscopique, permet la récupération du Pt en atmosphère ambiante
The platinum nanoparticles used as catalyst in Proton Exchange Membrane Fuel Cells (PEMFCs) represent around the half of the total price of the cell and is one of the limitations for their large scale commercialization. The treatment of spent PEMFC through the recovery of platinum catalyst is a major concern for their development. Usual recovery routes for platinum-containing catalysts are pyro-hydrometallurgical processes that generate pollutant emissions (CO2, NO2). An electrochemical recovery route by coupling electrochemical leaching and electrodeposition in ionic liquids (ILs) is proposed here, more environmentally friendly, performed in "soft" temperature conditions and without any gases emission. Studies of several electrolytes lead us to select BMIMTFSI + BMIMCl melts (bis(trifluorométhylsulfonyl) imidure + 1-butyl-3-méthylimidazolium chloride), due to the complexing ability of chloride against platinum and the good electrochemical stability of the RMIM+ cation. TFSI-, a weakly coordinate anion, allows us to modulate the complexing ability of the electrolyte, which is a key parameter affecting the nature and the electrochemical stability of the Pt complex formed after leaching. The optimal conditions of the leaching and electrodeposition steps have been determined during this work and successfully applied to PEMFC’s electrode. The selected electrolyte, which is weakly hygroscopic, allows the Pt recovery under ambient atmosphere

En raison du risque d’un approvisionnement insuffisant en ressources primaires des terres rares et des impacts environnementaux générés par les zones minières, le concept de l’agromine paraît être une solution très prometteuse. Il permet d’extraire des métaux lourds à partir de sols pollués ou de friches industrielles, par une méthode respectueuse de l’environnement, grâce à la culture de plantes hyperaccumulatrices. Une fois la culture réalisée, des procédés hydrométallurgiques sont développés afin d’extraire des plantes les métaux ayant une valeur économique importante. Le présent travail vise à développer des procédés hydrométallurgiques pour l’extraction des terres rares à partir d’une plante hyperaccumulatrice appelée Dicranopteris dichotoma. Cette fougère est connue pour sa capacité à accumuler les terres rares, notamment les légères, dans sa partie aérienne. Différentes voies d’extraction, puis de séparation des terres rares des autres éléments, ont été étudiées. Dans un premier temps, des lixiviations de la biomasse sèche ont été mises en oeuvre. Les rendements de lixiviation selon la nature de l’extractant ont ainsi pu être comparés. Pour cette voie, une précipitation est ensuite effectuée, suivie d’une calcination pour obtenir les oxydes de terres rares. Dans un second temps, la lixiviation de la biomasse sèche a été intensifiée par un procédé d’échange d’ions au cours duquel les terres rares sont fixées sur la résine. Après avoir percolé sur la résine des solutions qui permettent d’éliminer des impuretés, l’élution permet d’obtenir une solution concentrée de terres rares. Enfin, une troisième voie d’extraction est réalisée à partir des cendres de D. dichotoma, après une étape de combustion. Cette voie repose sur une lixiviation alcaline des cendres permettant l’élimination des impuretés solubles dans ce milieu. Une dissolution du résidu est ensuite effectuée, suivie d’une précipitation sélective des terres rares. Les trois voies étudiées s’avèrent en fait complémentaires et la combinaison de certaines étapes peut s’avérer prometteuse, notamment pour éliminer certaines impuretés. L’étude de ces procédés et de leur combinaison mérite d’être poursuivie afin d’améliorer les rendements d’extraction et la pureté du produit final. Il s’agira ensuite de développer un procédé à l’échelle pilote puis industrielle
Due to the risk of primary resource supply of rare earths and the environmental impacts generated by mining areas, the concept of agromining seems to be a very promising solution. It allows the extraction of heavy metals from polluted soils or industrial wastelands, by an environmentally friendly method, thanks to the cultivation of hyperaccumulating plants. Once the culture is completed, hydrometallurgical processes are developed in order to extract from plants the metals having a significant economic value. The present work aims to develop hydrometallurgical processes for the extraction of rare earths from a hyperaccumulator plant called Dicranopteris dichotoma. This fern is known for its high ability to accumulate rare earths, especially light ones, in its aerial part. Different extraction and separation ways of rare earths from other elements have been studied. At first, leaching of dry biomass was implemented. The leaching yields according to the nature of extracting solutions could thus be compared. For this approach, precipitation is then performed, followed by calcination step to obtain rare earth oxides. In a second approach, the leaching of dry biomass was intensified by an ion exchange process during which, the rare earths are fixed on the resin. After percolating solutions on the resin in order to eliminate impurities, an elution step leads to obtain a concentrated solution of rare earths. Finally, a third extraction process is carried out from the ashes of D. dichotoma, after a combustion step. This approach is based on an alkaline leaching of the ash allowing the elimination of soluble impurities in this medium. The residue is then dissolved, followed by rare earths selective precipitation. These three approaches studied, are actually complementary and the combination of certain steps can be promising, especially to eliminate some impurities. The study of these processes and their combination deserves to be pursued in order to improve the extraction yields and the purity of final product. It will then develop a pilot scale and industrial process

La lixiviation en tas est une méthode industrielle utilisée pour traiter des minerais à basse teneur consistant en la percolation d’une solution de lixiviation à travers un tas de 6 à 9 mètres de haut afin d’en extraire l’élément d’intérêt. Cependant, la présence de nombreuses fines particules et d’argiles au sein du minerai peuvent causer l’apparition de phénomènes de colmatage dans les tas, diminuant l’efficacité de la lixiviation. Afin de résoudre ce problème, les industries du nickel, du cuivre ou encore de l’uranium agglomèrent le minerai, augmentant ainsi sa granulométrie par le rassemblement des fines particules. Néanmoins, l’agglomération de minerais uranifères ainsi que l’impact de la structure des agglomérats sur la lixiviation reste peu étudiée. Cette thèse a permis de caractériser l’évolution structurale et pétro physique des agglomérats de minerais d’uranium au cours de la lixiviation, d’étudier l’influence des conditions d’agglomération sur la structure des agglomérats résultants et enfin d’étudier la lixiviation des agglomérats à l’échelle du tas, par le biais d’essais en colonnes métriques. De plus, les causes de colmatage ont pu être identifiées comme provenant d’une dégradation mécanique des agglomérats entrainant une réduction de la perméabilité et de la porosité du tas
Heap leaching allows processing low grade ores. Basically, this industrial mining process consists in percolating a leaching solution slowly down through an ore heap of 6 to 9 meters high to extract the metals of interest. However, fine particles and clays are often the cause of clogging within heaps, leading to a decrease of leaching efficiency. To solve this problem, copper, nickel and uranium industry uses agglomeration of the ore particles. This process allows adjusting the particle size distribution by gathering fine particles. However uranium-ore agglomeration and the impact of the agglomerates structure on heap leaching remains poorly understood. The current thesis allowed characterizing structural and petrophysical properties of agglomerates and its evolution during leaching, studying the influence of agglomeration conditions on agglomerates structures and finally upscaling there results at the heap scale, using meter scale columns. Clogging phenomena were especially due to the mechanical degradation of agglomerates, causing a decrease of both heap porosity and permeability

Un procédé innovant de production de fer par électrolyse d’une suspension d’oxydes de fer en milieu alcalin concentré est développé au centre de recherche d’ArcelorMittal de Maizières-lès-Metz. Ce procédé s’il atteignait la maturité industrielle permettrait de réduire significativement les émissions de dioxyde de carbone associées à l’industrie sidérurgique, en remplaçant le carbone utilisé comme agent réducteur dans les hauts-fourneaux par de l’électricité. Bien que ce procédé permette la production de fer à partir d’hématite commerciale (Fe2O3) à une densité de courant de l’ordre de 1000 A.m-2 avec une efficacité faradique supérieure à 80%, une dégradation des performances est systématiquement constatée lors de l’électrolyse de minerais de fer. Les impuretés majoritaires de ces minerais sont les oxydes et hydroxydes d’aluminium et de silicium, des composés solubles dans la soude concentrée. Ces composés pourraient donc être à l’origine de la baisse de réactivité observée lors de l’alimentation du procédé par des minerais de fer. Ainsi afin de tenter d’améliorer les performances de l’électrolyse alcaline à partir de minerais, des traitements de lixiviation alcaline sur un minerai défini ont été effectués dans cette thèse. La réactivité des minerais avant et après traitement a été comparée par chronoampérométrie. Bien que suite à l’élimination de ses composés alumineux, le minerai traité ait vu son rendement faradique réhaussé à environ 80% pour une valeur avant pré-traitement de 65%, sa densité de courant est restée deux fois moins élevée que celle de l’hématite pour une même tension électrique appliquée. Des expériences d’ajout d’ions aluminates et d’ions silicates lors de l’électrolyse d’hématite pure n’ont de plus eu pratiquement aucun effet indésirable sur son électrolyse. Les diverses expériences conduites dans cette thèse laissent supposer que les impuretés traitées n’ont que peu d’influence sur la réactivité des minerais. Le procédé est en revanche très sensible à la granulométrie des particules de minerais. Par ailleurs de forts phénomènes d’agglomération, qui n’ont pas lieu avec les oxydes de fer purs, ont été constatés lors de mesure de granulométrie du minerai étudié. Ainsi les expériences réalisées laissent supposer qu’un autre phénomène, probablement lié à la granulométrie secondaire des minerais en milieu alcalin concentré, soit à l’origine de la baisse de réactivité observée lors de leur électrolyse. Parallèlement une analyse thermodynamique avancée a été menée afin de déterminer les meilleures conditions théoriques de pression, de température et de concentration en NaOH pour effectuer l’électrolyse de l’hématite. La solubilité des composés de la gangue a été représentée avec des équations de Pitzer, et de nouveaux paramètres ont été calculés pour les interactions Na-SiO3-Al(OH)4. Cette étude thermodynamique a permis la conception et le pré-dimensionnement d’une étape de traitement des minerais par lixiviation alcaline
An innovative ironmaking process by alkaline electrolysis of suspended iron oxides is being developed at ArcelorMittal Global R&D Maizières-lès-Metz. Were it to achieve industrial maturity, this process would permit a significant reduction of steelmaking CO2 emissions. Indeed, the use of carbon as a reducing agent in blast furnace would be replaced by electricity. Although this process enables iron production from commercial hematite (Fe2O3) at current density of 1000 A.m-2 with faradaic efficiency higher than 80%, these performances are systematically lower when using iron ore instead. The main impurities in these ores are aluminium and silicon oxides and hydroxides, these compounds are soluble in concentrated sodium hydroxide solutions. These compounds could be the source of the decrease in reactivity observed when feeding the process with iron ores. To raise the electrolysis performance with iron ores, alkaline leaching treatments were conducted on a defined iron ore. Reactivity of iron ores before and after treatment was compared by chronoamperometry. Although the elimination of aluminous compounds resulted in the ore gaining a faradaic yield increase to a value of 80%, compared with 65% before treatment, its current density remained twice as low as the one of hematite for a same applied voltage. Furthermore, complementary experiments of aluminate and silicate ions addition during pure hematite electrolysis did not have any deleterious effect on its electrolysis. Based on all the experiments undertaken in this PhD, it seems unlikely that siliceous and aluminous impurities hold an important effect on iron ore reactivity in alkaline electrolysis. The process is nonetheless very sensitive to iron ores granulometry. On this subject, strong agglomeration phenomena were witnessed when measuring iron ores granulometry but did not occur with pure iron oxides. Therefore, it would seem that other phenomena may be the main cause of reactivity loss, these phenomena may well be linked to secondary granulometry of iron ores in concentrated alkaline media. In parallel, an advanced thermodynamic analysis was carried out to describe the best theoretical conditions for pressure, temperature and NaOH concentration to realize hematite electrolysis. Gangue compounds solubility was represented with Pitzer equations, and new parameters were calculated for Na-SiO3-Al(OH)4 interactions. This thermodynamic study enabled the design and pre-sizing of a treatment step for iron ores by alkaline leaching

L’agromine est une filière destinée à valoriser des métaux dispersés dans des sols ou autres matrices, à l’aide de plantes hyperaccumulatrices (HA). La première étape consiste à cultiver ces plantes pour obtenir des rendements élevés en métaux et la seconde, à produire des composés métalliques d’intérêt à partir de la biomasse. L’agromine a surtout été développée pour valoriser le nickel (Ni). Jusqu’à présent, la biomasse était brûlée pour concentrer le métal et éliminer les matières organiques. L’enjeu de cette recherche est de concevoir des procédés de récupération du Ni par extraction directe depuis la biomasse, sans brûler la plante. Il s’agit de comprendre les processus impliqués lors de l’extraction du Ni de la biomasse sèche à l’aide d’un solvant et déterminer les formes chimiques des espèces en solution. A partir de là seront mises en œuvre des opérations de séparation adaptées, pour isoler le Ni sous une forme intéressante pour des applications ultérieures. Les expériences de lixiviation à l’eau à 20 °C, menées avec deux HA contrastées, ont démontré qu’il était possible de transférer en solution jusqu’à 80% du Ni présent dans les tissus des plantes. Celui-ci est accompagné des ions majeurs et de composés organiques. L’analyse des composés et la modélisation des équilibres chimiques en solution ont montré que le Ni était complexé à plus de 95% par des ligands organiques, acides carboxyliques, porteurs du Ni dans la plante, ainsi que des complexants plus forts. A partir de ces résultats, des procédés de séparation ont été sélectionnés : la précipitation sélective et l’adsorption sur résine complexante. Ils ont permis de récupérer respectivement 75 et plus de 95% du nickel sous forme sulfure ou composé carboxylique. En revanche, la purification à l’aide de décanoate n’a pas permis d’isoler le Ni. Ainsi, ce travail a permis de mieux comprendre l’extraction du Ni directement à partir de plantes, la spéciation du Ni en solution multiconstituant en présence de ligands organiques, et de valoriser le nickel par des voies jusqu’alors inexplorées avec ce type de matière première
Agromining is a chain allowing the recovery of metals dispersed in soils or other matrices, using hyperaccumulator plants (HA). The first step is to grow these plants to achieve high yields of metals and the second to produce metal compounds of interest from the plant biomass. Agromining has mainly been developed to value nickel (Ni). Until now, biomass was burnt to concentrate the metal and remove organic matter. The challenge of this research is to design processes for Ni recovery by direct extraction from biomass, without burning the plant. It will allow a better understanding of the processes involved in the extraction of Ni from dry biomass using a solvent and the determination of the the speciation in the solution. Then, appropriate separation operations will be implemented to isolate the Ni in an interesting form for subsequent applications.Water leaching experiments, run at 20 ° C with two contrasted HAs, demonstrated that up to 80% of Ni could be transferred from the plant tissues to the solution. Ni is accompanied by major ions and organic compounds. The analysis of these compounds and the modeling of the chemical equilibria in solution showed that more than 95% of Ni was complexed by organic ligands, carboxylic acids (Ni carriers in the plant) as well as stronger complexing agents. From these results, separation processes were selected: selective precipitation and adsorption on complexing resin. They made it possible to recover respectively 75 and more than 95% of the nickel in sulphide or carboxylic compound forms. In contrast, purification with decanoate did not isolate the Ni.Thus, this work has made it possible to better understand the extraction of Ni directly from plants, the speciation of Ni in a multicomponent solution in the presence of organic ligands, and to valorize nickel by ways previously unexplored with this type of material

Le cobalt fait partie des cinquante métaux stratégiques, considérés comme essentiels pour l’industrie et qui sont au cœur d’enjeux économiques et géopolitiques mondiaux. C’est pourquoi, la recherche portant sur la récupération de ce métal critique, à partir de déchets industriels ou urbains, est particulièrement importante pour les années à venir. L’objet de la thèse porte sur le développement d’un procédé hydrométallurgique permettant de récupérer le cobalt à partir d’un lixiviat de batterie Li-ion par précipitation. La première partie de ces travaux s’est portée sur le choix de l’agent précipitant, celui-ci devant répondre à un certain nombre de critères tels qu’une haute efficacité de récupération du cobalt, un impact environnemental faible et un coût économique limité. Une étude comparative des agents a été effectuée, basée sur la littérature ainsi que sur des simulations des équilibres thermodynamiques réalisées sous Visual Minteq 3.0. Les résultats ont montré qu’il était possible de récupérer 99,8 % du cobalt, sous forme d’hydroxyde. Des expériences ont alors été conduites afin de valider les hypothèses émises et de comparer les résultats obtenus avec les simulations effectuées. Expérimentalement, plusieurs paramètres opératoires ont été étudiés afin de déterminer les conditions optimales de récupération du cobalt, en termes de rendement, de sélectivité et de filtrabilité du précipité. Certains paramètres tels que la sursaturation, peuvent influencer les propriétés du produit obtenu (taille des particules, des agglomérats, polymorphisme…). Le polymorphe retenu devra permettre d’obtenir les rendements les plus élevés et des temps de filtration les plus faibles. Par la suite, les recherches ont porté sur l’étude de milieux synthétiques complexes contenant du cobalt, du manganèse, se rapprochant ainsi des conditions réelles de lixiviats de batterie Li-ions, et conforme au schéma de procédé proposé. Enfin, à partir des résultats obtenus réacteur parfaitement agité en régime discontinu, des expérimentations ont été réalisées en mode continu. Il a été possible de déterminer les paramètres optimaux de récupération du cobalt et de les extrapoler à l’échelle pilote en réacteur à lit fluidisé, permettant d’envisager le procédé à plus grande échelle
Cobalt is one of the fifty strategic metals considered essential for the industry and which are at the heart of global economic and geopolitical issues. This is why, research into the recovery of this critical metal, from industrial or urban waste, are particularly important for the years to come. The subject of the thesis is the development of a hydrometallurgical process to recover cobalt from a Li-ion battery leachate by precipitation. The first part of the thesis focused on the precipitating agent choice, which must meet a certain number of criteria in order to recover cobalt efficiently. Based on these criteria, a comparative study of the different precipitating agents was carried out. It was based on the literature as well as on the simulations of thermodynamic equilibria carried out in Visual Minteq 3.0. The results showed that it was possible to recover 99.8% of cobalt, in the hydroxide form. Based on these results, experiments were conducted to validate the hypotheses put forward and to compare the results obtained with the simulations performed. Experimentally, several parameters were studied in order to determine the optimal conditions for cobalt recovery, in terms of yield, filterability and selectivity. Certain parameters such as supersaturation can influence the product obtained typology (particle size, agglomerate size, polymorphism...). The selected polymorph should allow to obtain the highest yields and the lowest filtration times. Subsequently, the research focused on the study of complex synthetic media containing cobalt and manganese, thus getting closer to the real conditions of Li-ion battery leachates, and appearing on the proposed process scheme. Experimental results were compared to simulations previously carried out. Finally, based on the results obtained in discontinuous mode, experiments were carried out in continuous mode. It was possible to determine the optimal parameters for cobalt recovery and to extrapolate them to the pilot scale in a fluidized bed reactor, allowing the process to be considered on a larger scale

Dans le procédé de refusion à l’arc sous vide, la structure et la dynamique de l’arc électrique conditionnent les distributions spatiales d’énergie et de courant au sommet du lingot refondu. Ces distributions impactent fortement les champs de température et de vitesse du métal liquide, qui gouvernent les conditions de solidification du lingot et donc la qualité finale du produit. Une étude par mesures optiques, de la dynamique de l’arc aux longues échelles de temps lors de refusions industrielles d’alliages de titane a été entreprise. Cette analyse a été effectuée par une méthode qualitative, à l’aide d’enregistrements vidéo, et par une nouvelle méthode de diagnostic quantitative développée spécifiquement dans ce travail, à base de photodiodes. L’analyse de la dynamique de l’arc confirme la présence d’un mouvement d’ensemble de l’arc électrique lors de refusions d’alliages de titane et montre une forte corrélation entre la dynamique observée et l’intensité du brassage électromagnétique imposé. Nos résultats ont de plus permis de prédire la dynamique probable de l’arc dans des conditions non étudiées et de proposer de possibles origines à la dynamique observée. Enfin, une première approche de modélisation de cette dynamique dans le logiciel de simulation RAVEL est proposée afin d’étudier son impact sur la solidification du lingot. Ce travail présente également une modélisation détaillée des rayonnements thermiques émis au sommet du lingot, basée sur la méthode des radiosités
In the vacuum arc remelting process, the structure and dynamics of the electric arc are responsible for the spatial distributions of energy and current at the top of the remelted ingot. Those distributions strongly impact the ingot temperature field and the liquid metal velocity field, which govern the ingot solidification conditions, hence the final product quality. A study based on the optical measurement of the electric arc dynamics at a long time-scale during vacuum arc remelting of titanium alloys was undertaken. This analysis was performed either qualitatively using melt video recordings, or quantitatively by a new specifically developed diagnostic technique based on the use of photodiodes. The analysis of the electric arc dynamics confirmed the presence of an ensemble arc motion during vacuum arc remelting of titanium alloys and showed a strong correlation between the observed dynamics and the magnitude of the imposed electromagnetic stirring. Furthermore, our results allow to predict the arc dynamics in non-studied conditions and to propose possible origins for the observed behaviors. Finally, a first simulation of the influence of the arc behavior is proposed in order to study its impact on the ingot solidification. This work comprises also a detailed modelling of the thermal radiation at the ingot top, based on the radiosity method

L’augmentation de la démographie mondiale (de 2,5 milliards en 1950 à 10 milliards d’habitants en 2050 selon l’Organisation des Nations Unies) entraine une augmentation des besoins en métaux. Ces métaux proviennent des mines, mais leur production à partir des minerais engendre d’énormes quantités de résidus. Ces derniers occupent de grands espaces de stockage et contiennent encore des métaux qui peuvent être extraits. La valorisation de ces résidus permettrait non seulement de réduire leurs volumes et leurs empreintes écologiques, mais aussi et surtout de produire des métaux à forte valeur ajoutée pour répondre aux besoins des nouvelles technologies. Deux types de résidus riches en fer ont été étudiés dans ce travail afin d’extraire le fer et le zinc qu’ils contiennent par électrodéposition : les boues rouges et la jarosite. Dans le premier cas, il s’agit des résidus provenant de la production de l’alumine à partir du minerai de bauxite par le procédé Bayer (procédé alcalin). Le deuxième type de résidu, la jarosite, provient de la production du zinc par le procédé « jarosite » en milieu acide. Pour ce faire, deux approches expérimentales ont été mises en place. Une électrodéposition directe dans le cas de boues rouges : les échantillons sont directement mis en suspension dans une solution de NaOH 12,5 mol/L et le fer (sous forme d’hématite et/ou de goethite) est électrodéposé sur une cathode en graphite à une température de 110°C. Pour le cas de la jarosite, une démarche différente a été mise en place : (i) une lixiviation de la jarosite en milieu acide sulfurique, (ii) une lixiviation de blende pour réduire le fer ferrique en fer ferreux et enrichir le bain en zinc, (iii) une cémentation du cuivre par une poudre de zinc et enfin (iv) une étape d’électrodéposition d’alliage fer-zinc. Dans les deux cas de résidus, plusieurs paramètres opératoires ont été testés afin d’optimiser les rendements de lixiviation, de cémentation, la qualité des dépôts et les rendements faradiques. En ce qui concerne les boues rouges, les meilleurs rendements faradiques (72%) ont été obtenus pour un ratio solide/liquide de 1/3 (g/mL), une concentration en NaOH de 12,5 mol/L, une densité de courant de 41 A/m² et une température de 110°C. Les dépôts du fer électrolytique, analysés par ICP-AES, DRX, MEB/EDX, présentent une pureté supérieure à 97% massique en fer. Pour la jarosite, les meilleurs rendements de lixiviation (en zinc et en fer étaient de 73% et 70% respectivement) ont été obtenus pour une concentration d’acide sulfurique égale à 1,5 M, un rapport solide/liquide 1/10 (g/mL) et une température de 80°C pendant 7 heures. Les essais d’électrodéposition ont permis de produire des alliages zinc –fer à différentes teneurs en fer. Les rendements faradiques obtenus dans les conditions optimales (densité de courant de 800 A/m² et une température de 20°C) étaient de l’ordre de 89%. Les résultats obtenus dans cette étude confirment la faisabilité technique d’électrodéposition du fer et d’alliage fer-zinc à partir des matrices complexe. Cela ouvre une nouvelle alternative à la valorisation des résidus miniers par la technique d’électrodéposition des métaux
The increase in world population (from 2.5 billion in 1950 to 10 billion in 2050 according to the United Nations) is leading to an increase in the need for metals. These metals come from mines, but their production from ores generates huge quantities of tailings. These tailings occupy large storage areas and very often contain metals that can be extracted. The recovery of these metals would not only make it possible to reduce their volume and ecological footprint, but also and above all to produce metals with high added value to meet the needs of new technologies. Two types of iron-rich residues were studied in this work in order to extract iron and zinc by electroplating: red mud and jarosite. In the first case, these are residues from the production of alumina from bauxite ore by the Bayer process (alkaline process). The second type of residues, jarosite, comes from the production of zinc by the "jarosite" process. Two experimental approaches have been set up for this purpose. Direct electrodeposition in the case of red mud: the samples are directly suspended in a 12.5 mol/L NaOH solution and the iron (in the form of hematite and/or goethite) is electrodeposited on a graphite cathode at a temperature of 110°C. In the case of jarosite, a different approach has been used: (i) a leaching of the jarosite in a sulphuric acid medium, (ii) a blende leaching to reduce the ferric iron to ferrous iron and to enrich the bath in zinc, (iii) a cementation of the copper by a zinc powder and finally (iv) an iron-zinc alloy electrodeposition step. In both cases of residues, several operating parameters were tested in order to optimize leaching yield, electrodeposition, deposit quality and faradaic yield. For the red mud, the best faradaic yield (72%) were obtained for a solid/liquid ratio of 1/3 (g/mL), a NaOH concentration of 12.5 mol/L, a current density of 41 A/m² and a temperature of 110°C. The electrolytic iron deposits, analyzed by ICP-AES, DRX, SEM/EDX, have a purity of more than 97% iron by mass. For jarosite, the best leaching yield (for zinc and iron were 73% and 70% respectively) were obtained for a sulphuric acid concentration of 1.5 M, a solid/liquid ratio of 1/10 (g/mL) and a temperature of 80°C for 7 hours. Electrodeposition tests produced zinc-iron alloys with different iron contents. The faradaic yield obtained under optimal conditions (current density of 800 A/m² and a temperature of 20°C) was of the order of 89%. The results obtained in this study confirm the technical feasibility of iron and iron-zinc alloy electroplating from complex matrices. This opens up a new alternative to the valorisation of mining residues by the metal electrodeposition technique

1. Quality management system – Requirements, OAO "ВНИИС" ed. Moscow: 2015. 2. The Process Aproach in ISO 9001:2015, International Organization for Standardization ed. Vernier, Geneva, Switzerland.
Supply chain management is the combination of different processes of supply, production and distribution in order to manage the flow of goods and service and transformation raw materials into final product. The main objectives of supply chain management are minimizing costs, decreasing fulfillment time, improving the quality of products, increasing flexibility, diversity and the reaction. Moreover, it is necessary to keep cost down by minimizing shortages. Supply chain management improves productivity. One more statement is the efficiency of operations that directly lies in logistics process management. ISO 9001:2015 sets criteria of system of quality management and outlines the only standard in its series. The process approach is the component of the given standard. It incorporates the Plan-Do-Check-Act (PDCA) cycle and risk-based thinking. So, all processes are managed and kept under control.
Управління ланцюгами поставок - це поєднання різних процесів постачання, виробництва та розподілу з метою управління потоком товарів та послуг та перетворенням сировини в кінцевий продукт. Основними цілями управління ланцюгами поставок є мінімізація витрат, зменшення часу виконання, поліпшення якості продукції, збільшення гнучкості, різноманітності та реакції. Більше того, необхідно зменшувати витрати, мінімізуючи дефіцит. Управління ланцюгами поставок покращує продуктивність праці. Ще одним твердженням є ефективність операцій, яка безпосередньо полягає в управлінні логістичним процесом. ISO 9001: 2015 встановлює критерії системи управління якістю та окреслює єдиний стандарт у своїй серії. Процесний підхід є складовою даного стандарту. Він включає цикл "Плануй-виконай-перевіряй" (PDCA) та мислення, засноване на оцінці ризику. Отже, усі процеси управляються та тримаються під контролем.

Limiter les émissions de dioxyde de carbone (CO2) est devenu un enjeu d’envergure internationale, notamment pour les industries des secteurs énergétique, chimique et métallurgique. À cette fin, des technologies de captage de CO2 ont été développées durant ces dernières décennies. Dans cette étude, nous nous intéressons à trois types de technologies de captage de CO2 : par absorption chimique à la MEA, par séparation membranaire et par adsorption sur charbon actif. Le CO2 considéré est émis par une centrale à charbon puis directement valorisé au sein d’un procédé de fabrication sur le même site. L’objectif de cette étude est de quantifier les bénéfices environnementaux de l’installation d’une technologie de captage de CO2, en comparaison à la configuration actuelle, sans captage du CO2. Notre approche associe modélisation systémique des procédés et analyse de cycle de vie (ACV). La méthodologie adoptée consiste à modéliser le système complet (la centrale, le procédé de fabrication et les différentes unités de captage) en utilisant un logiciel de diagrammes de flux (Aspen Plus), puis à déterminer les impacts environnementaux par une ACV. Les résultats montrent que le procédé par adsorption chimique à la MEA est fortement pénalisé par l’utilisation du solvant, tant en ce qui concerne la consommation énergétique que les impacts environnementaux. Le procédé membranaire montre des impacts environnementaux importants, malgré une consommation énergétique bien plus faible, en raison de l’utilisation massive de polymères (matériaux membranaires). Enfin, le procédé par adsorption au charbon actif présente des impacts environnementaux moins élevés que les deux autres procédés dans la grande majorité des catégories d’impact
Limiting carbon dioxide (CO2) emissions is a major global issue, particularly for the energy, chemical and metallurgical industries. To this end, CO2 capture technologies have been developed in recent decades. In this study, we focused on three types of CO2 capture technologies: chemical absorption by MEA, membrane separation and activated carbon adsorption. The CO2 considered is emitted by a coal-fired power station and then directly valorized within a manufacturing process on the same site. The objective of this study was to quantify the environmental benefits of installing a CO2 capture technology in comparison to the current configuration, without CO2 capture. Our approach combined process modeling and life cycle assessment. The methodology adopted was to model the complete system (the power plant, the manufacturing process and the various capture units) using a flowsheeting software (Aspen Plus), then to determine the environmental impacts by LCA. The results show that the MEA chemical adsorption process is strongly penalized by the use of the solvent, both regarding the energy consumption and the environmental impacts. The membrane process exhibits significant environmental impacts, despite a much lower energy consumption, due to the massive use of polymers (membrane materials). Finally, the activated carbon adsorption process has lower environmental impacts than the other two processes in the vast majority of impact categories

Dissertação de mestrado em Engenharia Mecânica (área de especialização em Tecnologias de Manufactura)
Este projecto foi desenvolvido em colaboração com a empresa Delabie, uma empresa de fundição instalada em Braga que produz componentes metalo-sanitários em latão, com o objectivo de estruturar e implementar um sistema de controlo e optimização do processo de fabrico. Neste relatório apresenta-se o trabalho desenvolvido. Inicialmente é feita uma descrição do processo implementado na empresa, conhecimento que é necessário para permitir efectuar o melhoramento e o aperfeiçoamento do sistema produtivo, já que um dos objectivos do trabalho consistiu na criação de documentação onde, para cada etapa e referência de peça se possa saber qual o método/parâmetros a utilizar no processamento, bem como garantir a repetibilidade do processo. Apesar de se terem detectado diversos problemas nas várias etapas do processo produtivo causando a formação de defeitos e a produção de peças rejeitadas, apenas se focou atenção na primeira etapa do processo: produção de machos. Foi possível verificar que as peças obtidas possuíam normalmente defeitos, nomeadamente: rugosidade e aderência de areia à peça, defeitos que à partida serão atribuíveis, aos machos. Por essa razão, estudou-se a influência dos parâmetros de produção dos machos, nomeadamente da composição química da areia e da temperatura de cura, no nível de defeitos detectado Os resultados obtidos para as diferentes formulações de areia realizadas, com distintas proporções de resina e endurecedor, permitiram seleccionar a melhor composição para aplicação no processo produtivo. E os testes efectuados para diferentes temperaturas de cura permitiram definir qual o valor mínimo para se garantir uma maior qualidade da peça final. Efectivamente, os melhores resultados foram obtidos para um teor de resina de 1,7%, inferior ao teor de 2% normalmente utilizado na empresa, e para temperaturas de cura compreendidas entre 180-220ºC, valores superiores aos inicialmente utilizados (150-180 °C). Adicionalmente ao trabalho desenvolvido na secção de fabrico de machos, foram desenvolvidos e implementados documentos onde se encontram descritos os modos operatórios gerais de cada secção, bem como os modos operatórios específicos para cada referência de peça, por forma a garantir a sistematização do processo e assegurar o cumprimento adequado dos procedimentos. Finalmente, os kanbans utilizados pela empresa foram igualmente melhorados e optimizados tendo-se criado uma base de dados onde a informação recolhida pelas folhas de seguimento é armazenada. Com esta base de dados é possível acompanhar a evolução do processo de forma a saber a variação da quantidade de peças não conformes, estudar os defeitos típicos para cada referência, criar uma curva ABC onde se verifica quais são as referências criticas, entre outros aspectos. A realização deste trabalho contribuiu para que a empresa aumentasse significativamente o seu conhecimento relativamente às zonas mais críticas do processo e às melhores técnicas disponíveis a adoptar no fabrico de machos para minimização do número de rejeitados. Paralelamente, foi concretizada a implementação e sistematização de um processo de controlo de qualidade nas distintas secções que integram o processo produtivo e que seguramente contribuirão para elevados níveis de desempenho e melhor posicionamento da empresa no mercado dos fabricantes de produtos metalo-sanitários em latão.
This project has been developed in collaborations with Delabie, a foundry situated in Braga that produces sanitary products in brass. The project aims to control and optimize the production process. This report is presents the developed work. The first part describes the actual process implemented in the company, which knowledge is necessary to perform the improvement and enhancement of the productive system, since one of the objectives of the present work aims the development of documentation to register, for each step and reference, which method / parameters should be used in the production process, ensuring that they will be produced every time in the same controlled way. In the initial phase of the project it was possible to detect some problems in the process that results in the formation of defects and in the production of rejected pieces. However the attention was only focused in the first part of the process: production of the cores. It was possible to verify that the parts obtained in this section usually exhibited defects, including: surface roughness and adhesion of sand to the piece, defects which appear to be attributable to the cores. Therefore, the influence of the production parameters of the cores, namely the chemical composition of the sand and of the curing temperature on the level of defects detected has been studied. The results obtained for the different formulations made of sand with different proportions of resin and hardener allowed to select the best composition to use in the production process and the tests performed for different cure temperatures allowed to set the minimum value to ensure a higher quality of the final part. In fact, the best results were obtained for a resin content of 1,7%, lower than the 2% normally used in the company, and for temperatures ranging from 180 to 220ºC, higher than the normally used in the company (150 to 180 ºC) . In addition to the work done in the optimization of core production, some documents where developed and implemented to describe the general operational procedures for each section and to specify the operating data for each reference, to ensure a process systematisation and the correct compliance with the company procedures. Finally, the kanban used by the company have also been improved and optimized creating a database where information collected by the monitoring sheet is stored. With this database it is possible to monitor the process evolution in order to identify the variation of the amount of non-conforming parts, study the typical defects for each reference and create a curve ABC with the critical references, among others. This project as contributed to increase the company knowledge of the most critical areas of the process and identify the best available practices techniques to be adopted in the manufacture of cores to minimize the number of rejects. In parallel the implementation and systematization of a process of quality control in the different sections that make up the production process of the production process will certainly contribute to high levels of performance and better position the company in the market of manufacturers of metal-sanitary brass.

Dissertação de mestrado integrado em Engenharia de Materiais
O presente estudo incide sobre o processamento de ligações γ-TiAl/Ti6Al4V por brasagem por difusão com recurso a multifolhas Al/Cu. Foi avaliada a influência das variáveis de processamento (composição química global do sistema multifolhas, temperatura de brasagem, tempo de estágio de brasagem e pressão de processamento) na composição química e microestrutura das interfaces. Em função das espessuras das folhas de Al e Cu disponíveis, selecionou-se as sequências de multifolhas Cu/Al/Cu e Al/Cu/Cu/Al, de forma a que as suas composições químicas globais se ajustassem, o mais possível, à do eutético Al-Cu e à de uma solução sólida de Al no Cu, respetivamente. O processamento das ligações foi efetuado em vazio, com temperaturas de brasagem de 625 e 725 ºC, com tempos de estágio à temperatura de brasagem de 60 e 120 minutos e com pressões de 4 e 10 MPa. A microestrutura e a composição química das interfaces foram analisadas por Microscopia Eletrónica de Varrimento (MEV) e Espetroscopia de Dispersão de Energias (EDS), respetivamente. As interfaces obtidas, independentemente das condições de processamento, apresentam sempre algumas zonas com fissuras e poros. No processamento efetuado a 625 ºC, durante 60 minutos, com a configuração Cu/Al/Cu e uma pressão de 4 MPa, a ligação ocorreu pela formação de duas camadas de reação, ambas constituídas por Al3Ti. Com uma pressão de 10 MPa, a interface não apresenta em nenhuma zona a morfologia típica do eutético, o que indica que durante o processo de ligação não houve formação de fase líquida. O aumento da temperatura para 725 ºC induz alterações na microestrutura, que se caracterizam por um maior grau de heterogeneidade, já o aumento do tempo de estágio para 120 minutos não induz alterações significativas. O processamento efetuado a 625 ºC, com a configuração Al/Cu/Cu/Al resultou na formação de uma interface homogénea mas não inibiu a formação da fase frágil Al2Cu. Para a mesma configuração e uma temperatura de 725 ºC a interface apresenta fases potencialmente mais resistentes a temperaturas elevadas e as fases Al2Cu e (Al) foram eliminadas.
The joining of a gamma based titanium aluminide alloy to Ti6Al4V alloy by diffusion brazing with Al/Cu multifoils was studied. In this study the influence of the processing variables (global chemical composition of multifoils system, brazing temperature, dwell time and pressure) on the chemical composition and microstructure of interfaces was evaluated. Joining was carried out in vacuum at 625 and 725 ºC, for 60 and 120 minutes and with a pressure of 4 and 10 MPa. In this study different sequences of pure foils of Al and Cu (Cu/Al/Cu and Al/Cu/Cu/Al) were tested. The microstructure and chemical composition of the interfaces were analysed by Scanning Electron Microscopy (SEM) and by Energy Dispersive X-ray Spectroscopy (EDS), respectively. The bonding interfaces present some zones with cracks and pores, regardless of the processing conditions tested. Joining at 625 ºC, for 60 minutes, with the configuration Cu/Al/Cu and a pressure of 4 MPa was promoted by the formation of two reaction layers, both composed of Al3Ti. With a pressure of 10 MPa, the interface does not show in any typical morphology of eutectic zone, which shows that during the bonding process there was not formation of liquid phase. The increase in temperature to 725 ºC induces changes in microstructure, which we are characterized by a greater degree of heterogeneity. Increasing the dwell time to 120 minutes does not induce significant changes in the microstructure. Joining carried out at 625 ºC, with the configuration Al/Cu/Cu/Al resulted in the formation of an homogeneous interface but did not inhibit the formation of brittle phase Al2Cu. For the same configuration and a joining temperature of 725 ºC, the interface presents high temperature phases and phases Al2Cu and (Al) were eliminated.

Dissertação de mestrado integrado em Engenharia Mecânica
As ligas de alumínio são globalmente utilizadas em inúmeras atividades. Sendo estas, indústrias muito competitivas, existe a necessidade de um melhoramento constante de todos os intervenientes no processo produtivo. Essas melhorias têm como objetivo reduzir custos e/ou melhorar o desempenho dos componentes e têm vindo a ser efetuadas quer pelo recurso a novas técnicas de produção, quer pelo desenvolvimento de novas ligas/composições. Neste âmbito, o objetivo central deste projeto consistiu no estudo da conjugação de duas tecnologias distintas, Squeeze Casting e Ultrassons, para analisar a melhoria das propriedades mecânicas das ligas de alumínio, decorrentes dessa combinação. Inicialmente, foram realizados testes para cada uma das tecnologias singularmente, os quais se constituíram como ensaios de controlo, tendo sido depois avaliada a sua conjugação para diversos parâmetros. Foi desenvolvido um projeto para um equipamento experimental com vista à realização dos ensaios, mas, por motivos alheios ao autor, não foi possível a sua construção. No entanto, com recurso à colaboração de uma empresa local, foram realizados ensaios para estudar o efeito da conjugação das duas tecnologias. Mais especificamente, foi estudado o efeito de dois níveis de pressão distintos – 5 e 10 MPa – e de dois métodos de aplicação de ultrassons ao banho metálico – direto isotérmico por via de um radiador acústico e indireto através da coquilha, durante a solidificação. Foram avaliadas as características microestruturais, a dureza e a densidade das amostras dos diferentes ensaios. Verificou-se que as amostras resultantes da conjugação das tecnologias apresentam características microestruturais muito favoráveis – afinadas e modificadas (silício e componentes intermetálicos) – quando comparadas com os ensaios de cada uma das tecnologias singularmente. Foi possível a obtenção de amostras com cerca de 98.5% da densidade teórica com a aplicação direta da pressão contra os 95,6% obtidos apenas com desgaseificação. Os resultados relativos à dureza não foram conclusivos. Os resultados parecem indicar que a conjugação das duas tecnologias é benéfica, permitindo a obtenção de componentes complexos, afinados e livres de porosidades com pressões relativamente baixas.
The aluminum alloys are used all over the world in countless industrial activities. These activities are very competitive and demand constant improvement of all the parts involved in the productive process. Those improvements, aimed to reduce costs or improve the components performance, are done by using new production technics or by the development of new alloys and their treatment. In this context, the main goal of the project consists in the study of the conjugation of two different technologies, Squeeze Casting and Ultrasonic Melt Treatment, to analyze the improvement of the mechanical characteristics in aluminum alloys resultant of that combination. An equipment project was developed to build an experimental machine for the trials, but, due to the state of the national economy, that goal was not achieved. Even though, thanks to a local company, it was possible to conduct the trials. The first ones were made with each technology alone and were considered control trials. Afterwards, the combination of the two technologies was evaluated using different parameters – two pressure values (5 and 10 MPa) and two ultrasonic application methods (direct isothermal, using an acoustic radiator, and indirect, through the mold, during the solidification). Several aspects where evaluated, such as, the microstructural characteristics, the hardness and the density of each sample. The samples obtained with the combination of the two technologies were refined and modified – both the silicon and the intermetallic particles. With the application of pressure during the solidification, the density value increased (98,5% of the theoretical density against 95,6% without the application of pressure). The hardness trials were inconclusive. The results seem to indicate that the combination of these two technologies is interesting and might allow the production of complex, refined and pores free components. Additionally, it may allow the reduction of the pressure values used in the Squeeze Casting operations.

Dissertação de mestrado em Engenharia de Materiais
O presente trabalho surge na sequência de um estudo exploratório que indicou a possibilidade de processar ligações Ti6Al4V/Ti6Al4V, por brasagem por difusão, mediante a utilização de multifolhas de Al e Cu como liga de brasagem. No entanto, as interfaces obtidas apresentam zonas com defeitos, como fissuras e falta de ligação. Sendo assim, o presente trabalho consiste na avaliação da influência das variáveis de processamento (temperatura de brasagem, pressão de processamento e composição química global das multifolhas) na microestrutura e composição química das interfaces, de modo a identificar as variáveis de processamento que permitam a produção de ligações isentas de defeitos. Foram processadas ligações, em vazio, à temperatura de brasagem de 625 ºC e 725 ºC, com as pressões de processamento de 4 MPa e 8 MPa, durante um tempo de estágio de 60 minutos, mediante a utilização de multifolhas de Al e Cu com diferentes empilhamentos e diferentes percentagens de Cu, a saber: Cu/Al/Cu (34,5% Cu), Cu/Al/Cu/Cu/Cu/Al/Cu (68,5% Cu), e Al/Cu/Cu/Al (93% Cu). A microestrutura e a composição química das interfaces foram analisadas por Microscopia Eletrónica de Varrimento (MEV) e por Espectroscopia de dispersão de Energias (EDS), respetivamente. As ligações efetuadas mediante a utilização da configuração Cu/Al/Cu, à temperatura de 625 ºC e 725 ºC sob uma pressão de 4 MPa, resultou na formação de interfaces compostas por duas camadas, essencialmente constituídas pelas fases Al3Ti, Al2Ti, AlTi, Al3CuTi, Al2Cu e (Al). Com o aumento da pressão para 8 MPa a microestrutura das interfaces alterou-se. À temperatura de 625 ºC a interface resultante apresenta quatro camadas compostas maioritariamente pelas fases (Al), Al2Cu, AlCu e Al9Cu11, e à temperatura de 725 ºC, a interface é essencialmente constituída por Al3Ti, Al2Ti, Al11Ti5, Al3CuTi, Al2Cu e (Al). A interface resultante do processamento utilizando a configuração Cu/Al/Cu/Cu/Cu/Al/Cu apresenta duas camadas, constituídas maioritariamente pelas fases Al4Cu9 + (Cu), Al2Cu3 e (Cu). As ligações efetuadas mediante a utilização da configuração Al/Cu/Cu/Al, à temperatura de 625 ºC sob as pressões de 4 MPa e 8 MPa, resultou na formação de interfaces compostas por seis camadas, maioritariamente constituídas pelas fases (Al), Al2Cu, AlCu, Al2Cu3 e (Cu). O aumento da temperatura de brasagem para 725 ºC, sob as pressões de 4 MPa e 8 MPa, resultou na formação de interfaces essencialmente constituídas pelas fases Al4Cu9 e (Cu). A ligação efetuada à temperatura de 725 ºC, durante 60 minutos, sob a aplicação de uma pressão de processamento de 4 MPa, mediante a utilização da configuração Al/Cu/Cu/Al, apresenta as condições de processamento mais favoráveis, visto que são as que induzem à formação de interfaces com menor nível de porosidade, fissuração e constituídas por fases estáveis a temperaturas de serviço mais elevadas, uma vez que as fases (Al) e Al2Cu não são detetadas na interface.
This work comes on the following of an investigation that highlighted the possibility of using Al/Cu multifoils as brazing filler for processing, by diffusion brazing, Ti6Al4V/Ti6Al4V joints. However, several defects, such as cracks and unbounded zones, were observed at the interfaces. The present work aims to evaluate the influence of the processing variables (brazing temperature, bonding pressure and chemical composition of the multifoils) on the microstructural features and chemical composition of the interfaces, in order to identify the set(s) of processing variables that enable the production of sound/defect free interfaces. Joints were processed in vacuum, at 625 ºC and 725 ºC, with a dwelling stage of 60 minutes and bonding pressures of 4 and 8 MPa, using different stacking sequences of multifoils, namely: Cu/Al/Cu (34.5 Cu, wt.%), Cu/Al/Cu/Cu/Cu/Al/Cu (68.5 Cu, wt.%) and Al/Cu/Cu/Al (93 Cu, wt%). The microstructure and the chemical composition of the resulting interfaces were analysed by Scanning Electron Microscopy (SEM) and by Energy Dispersive X-Ray Spectroscopy (EDS), respectively. The interfaces resulting from joining with Cu/Al/Cu multifoil, at 625 ºC and 725 ºC, under a bonding pressure of 4 MPa, consist of two layers and are essentially composed of Al3Ti, Al2Ti, AlTi, Al3CuTi, Al2Cu and (Al). The increase of the bonding pressure to 8 MPa induces changes on the interfaces. For joining at 625 ºC the interface consists of four layers and is mainly composed of (Al), Al2Cu, AlCu and Al9Cu11, while at 725 ºC the interface is essentially composed of Al3Ti, Al2Ti, Al11Ti5, Al3CuTi, Al2Cu e (Al). (Cu), Al2Cu3 and Al4Cu9 + (Cu) are the main reaction products that compose the interfaces resulting from using Cu/Al/Cu/Cu/Cu/Al/Cu multifoil. The use of Al/Cu/Cu/Al multifoil for joining at 625 ºC, with bonding pressures of 4 and 8 MPa, induces the formation of interfaces composed of six layers with (Al), Al2Cu, AlCu, Al2Cu3 and (Cu) as the main phases. The increase of the brazing temperature to 725 ºC, with bonding pressures of 4 and 8 MPa, promoted the formation of interfaces mainly composed of Al4Cu9 e (Cu). Joining with Al/Cu/Cu/Al multifoil at 725 ºC, with 4 MPa bonding pressure, enables the production of sounder joints, which should also withstand higher service temperatures, since (Al) and Al2Cu were not detected at the interfaces.

Dissertação de mestrado integrado em Engenharia Mecânica
Esta dissertação de mestrado tem como principal finalidade a análise e otimização do processo de fundição em estruturas finas – estruturas celulares metálicas. Partindo de uma análise bio mimética inspirada no funcionamento dos elementos constituintes da natureza pretende-se desenvolver conceitos e aplicar esses mesmos princípios na área da tecnologia de fabrico. O principal objeto de estudo é o efeito que estruturas rugosas podem ter no comportamento de escoamento de fluidos, bem como a otimização da sua morfologia. Pretende-se estudar e compreender o efeito que as superfícies rugosas das cavidades moldantes possam apresentar, no processo de transferência de calor e consequentemente na sua fluidez. O processo de fundição por cera perdida é o indicado para este tipo de estruturas, pois é dotado de boa qualidade dimensional e geométrica. São realizados alguns ensaios práticos de forma a analisar as fases de enchimento e respetivas taxas de solidificação durante a solidificação e enchimento do metal. Estes ensaios experimentais complementam diferentes níveis de rugosidade, para se compreender melhor a influencia deste fator. Utilizando como ligas de vazamento, respetivamente o alumínio (Al) e o bronze (CuSn), submetendo sempre o fluido a condições ideais de pressão e vácuo. São também apresentados alguns estudos relacionados com a transferência de calor e fundamentos teóricos que devem ser mencionados para que se possa adquirir uma maior sensibilidade na abordagem deste projeto. No final pretende-se determinar se a rugosidade pode influenciar, direta ou indiretamente este tipo de fundição, com o objetivo de otimizar o processo de fabrico de estruturas finas e detalhadas.
This dissertation has as main purpose the analysis and optimization of the casting process for thin structures - metal foams. From bio mimetic analysis inspired by the development of the constituent elements of nature is intended to develop concepts and apply these same principles in the manufacturing technology area. The effect it may have, rough structures on the behavior of fluid flow, as well as the optimization of their morphology, is the subject of this study. Aims to study and understand the effect that the rough surfaces of the cavities molding can be in the process of heat transfer and consequently in its fluidity. The process of lost wax casting is suitable for this type of structures, it is endowed with good quality and geometric dimensional. Some practical tests are performed in order to analyze the respective stages of filling and solidification rates during filling and solidification of the metal. These experimental complement different levels of roughness, to better understand the influence of this factor. Using as a casting alloys respectively the aluminum (Al) and bronze (CuSn) subjecting the fluid to always ideal conditions of pressure and vacuum. Also featured are some studies related to heat transfer and theoretical foundations that should be mentioned so that you can acquire a greater sensitivity in tackling this project. In the end it is intended to determine whether the roughness can influence, directly or indirectly such casting, in order to optimize the manufacturing process of fine structures and detailed.

Dissertação de mestrado integrado em Engenharia Mecânica
O presente trabalho enquadra-se no âmbito do Projeto de Dissertação inserido no Mestrado Integrado em Engenharia Mecânica da Universidade do Minho 5 ° Ano. Este projeto teve como principais objetivos, a análise e implementação de sistemas de controlo no processo de fundição e o acompanhamento de projetos de coquilha desenvolvidos na empresa DELABIE, que se dedica à produção de torneiras e válvulas em latão. Este trabalho iniciou-se com, uma revisão bibliográfica sobre temas ligados à tecnologia de fundição, vazamento por gravidade em moldação permanente, propriedades do latão e projeto de coquilha. Em paralelo, foram analisados os procedimentos da empresa, com principal incidência nas atividades de fusão, vazamento do latão e de projeto de coquilha. A partir da identificação dos problemas nas Atividades de Produção do posto de trabalho Vazamento de Peças, foram implementadas modificações no seu ciclo de produção, setup’s e perturbações do posto, permitindo aumentar a produção útil em 12%, melhorar a organização e uniformização das suas atividades. No âmbito da implementação de Procedimentos de Controlo, estabeleceu-se no procedimento de carregamento do forno um limite máximo de 30% para refusão de gitos, registando-se nas análises químicas das amostras do banho do forno, uma diminuição do desvio padrão na percentagem dos elementos de liga. O procedimento de controlo dos banhos de grafitização das coquilhas introduziu, atividades de monitorização da densidade dos banhos e de adição de grafite, uniformizando a densidade para 1,070 g/cm3. Os procedimentos de controlo dos parâmetros específicos de vazamento permitiram, criar uma base de dados das suas variáveis, sendo criados documentos de produção para cada uma das referências. De modo a avaliar o processo de “Projeto de Coquilha” utilizado na DELABIE, selecionaram-se duas referências, descrevendo os problemas e decisões tomadas em cada fase até, estas serem validadas para produção. Algumas das decisões tomadas de forma empírica, foram estudadas com recurso a ferramentas de simulação de fundição (NovaFlow&Solid), comparando os seus efeitos com os resultados obtidos no software.
This work is presented in the context of the Project for Dissertation inserted into the Master in Mechanical Engineering, University of Minho 5th Year This project had two main objectives, the implementation of control systems in the casting process and follow the development of permanent mold projects in DELABIE company, which is engaged in production of taps and valves in brass. This work began with a literature review on issues related to foundry technology with permanent mold by gravity pour, properties of brass and the cast mold design. In parallel, the company's procedures were analysed, with the main focus on fusion, brass casting and permanent mold design activities. From the identification of problems in the Production Activities on the PT Pouring, modifications were implemented in the production cycle, setup's and disorders of the stand, enabling the increase the useful production by 12%, improve the organization and standardization of activities. In the implementation of control procedures, settled in the loading procedure the oven a maximum of 30% gating’s remelt, registering on chemical analyses of samples from the furnace bath, a standard deviation decrease in the percentage of alloying elements. The control procedures for the shells graphitization introduced monitoring activities of the density of the baths and graphite added, standardizing the density to 1.070 g/cm3. The procedures for monitoring the specific pouring parameters allowed create a database of your variables and production documents being created for each reference. In order to evaluate the process of "Project Die Casting" employed in DELABIE, 2 references were selected with problems, describing the problems and decisions taken until they are validated for production. Some of the decisions made empirically, were studied using the casting simulation (NovaFlow & Solid) tools, comparing its effects with those obtained in the software.

Dissertação de mestrado integrado em Engenharia de Mecânica
A presente tese de mestrado expõe o estado da arte das barreiras de protecção rodoviária, com incidência mais profunda nas barreiras metálicas mais usuais, área de estudo deste trabalho. De modo a executar uma análise fidedigna, é descrita previamente a curva do material, obtida experimentalmente, que posteriormente é tratada de modo a obter a curva verdadeira do material para introdução no programa. As análises executadas são de cariz estático, estudando de forma individual estes dois elementos. Como se pretende verificar o comportamento plástico das mesmas, o estudo numérico recorre ao programa ANSYS que permite o estudo não-linear e plástico nas suas análises. Neste trabalho são executadas análises das ligações (prumo e espaçador) das barreiras de protecção rodoviária com vista ao entendimento do seu comportamento de deformação, comparando dois tipos de perfis, o UPN120 e o C125, retirando por fim as equações que descrevem o comportamento das diferentes estruturas, de modo a poder aplicar as análises numéricas a casos reais de colisão.
The present master degree dissertation exhibits the state of the art of the road safety barriers with special focus in the most usual metallic barriers, subject area of this work. In order to perform a realistic analysis, it is done an experimental test to obtain the stress-strain curve, which will be treated so the true stress-strain curve can be obtained in order to introduce it in the software. The analyses performed are static, and the two structures are independently analysed. In order to study the plastic behaviour in these structures, this work uses software that allows the non-linear and plastic behaviour in its analyses, the ANSYS. In this work are performed connection analyses (post and spacer) of the road safety barriers in order to understand their deformation behaviour, comparing the two post types, the UPN120 and the C125, achieving the final formulation that describes its behaviour, in order to able to apply that formulation in real crash cases.