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1
Coleman, Andrew John. "Filiform corrosion of aluminium alloys and iron." Thesis, Swansea University, 2007. https://cronfa.swan.ac.uk/Record/cronfa42908.
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Shollock, B. A. "Precipitation in rapidly solidified aluminium-chromium-iron alloys." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238185.
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Moshtaghie, A. A. "Interrelationships between aluminium and iron metabolism in man." Thesis, University of Newcastle Upon Tyne, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380213.
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Hull, S. "Precipitation in aluminium based and iron based alloys." Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370120.
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5
Sidhu, Mandeep Singh. "Liquid Aluminium Corrosion Characteristics of Cast Iron and Steel." Thesis, University of Canterbury. Mechanical Engineering, 2012. http://hdl.handle.net/10092/7013.
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Cast iron and steel alloys are commonly used for tooling and structural components in Al production, Al die-casting and the aluminizing industry due to their favourable properties including high strength, good formability and low cost. However, the iquid Al corrosion of these materials is one of the crucial concerns in maintaining the efficient production. Al is produced by the electrolytic smelting of alumina. Cast iron and/or cast steel pipes - commonly known as „tapping pipes‟ - are used to extract the liquid Al produced by smelting. Tapping pipes mainly degrade by material loss because liquid Al reacts with nearly all metals. Failure of tapping pipes is a significant contributor to the maintenance expenses; therefore, the primary aim of this research is to develop a material to enhance the life time of tapping pipes. Various test methods were developed in order to examine the effect of molten Al
environment on cast iron and steel alloys. The corrosion resistance of these alloys was determined under different conditions of Al flow and temperature. The intermetallic compounds formed by exposing the ferrous to liquid Al were characterized using the Energy Dispersive X-ray Spectroscopy (EDS) and Electron Back Scatter Diffraction (EBSD) techniques. The formation, growth and nature of reaction products were revealed to establish a link to the liquid Al corrosion resistance. A relationship between the chemical composition and liquid Al corrosion resistance of cast irons could not established in the past. In the present work, the corrosion rate was found to depend upon the graphite morphology and fraction of each Fe-C phase of cast
iron matrix, which can be controlled by selecting the chemical composition. Moreover, present research suggested the guidelines for producing a cast iron with enhanced liquid
Al corrosion resistance. The presence of C-rich phases, graphite flakes and cementite was found to be effective in enhancing the liquid Al corrosion resistance of gray cast
irons. Conversely, a higher Si content was found to enhance the susceptibility of cast irons to liquid Al corrosion.
The corrosion mechanisms for ferrous alloys in liquid Al are not fully understood. Thus the subsequent analysis of the dissolution data was supported by investigating the
reaction products formed between Al and substrate materials. In addition to commonly existent ε-Fe2Al5 and ζ-FeAl3 phases, the formation of Al4C3 and κ-Fe3AlC compounds was confirmed for the first time in the intermetallic layers of ferrous alloys. The Fe3Si phase in the intermetallic layers of high Si cast irons was found, which was believed to facilitate the high corrosion rates of high Si cast irons. Moreover, the mechanism by which C in Fe-substrates affects the liquid Al corrosion resistance can be better understood given the present work.
Furthermore, the analysis presented here gives an understanding of the nature, growth and dissolution of intermetallic compounds in several cast iron alloys. Higher Si
additions to cast irons played an important role in molten metal corrosion by accelerating the material loss and changing the nature of intermetallic layers. The results of this study
clearly indicated that the dissolution and the growth of intermetallic compounds are interrelated and the dissolution and/or spallation of the intermetallic layers may be the
primary mode of liquid Al corrosion of ferrous alloys.
6
Hale, Geoffrey Eric. "The structure and properties of iron-manganese-aluminium alloys." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434965.
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Humphreys, Elen Siobhain. "Production and characterisation of rapidly solidified Al-V-Fe alloys." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302070.
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8
Coscia, Carlo. "Transformation of an aluminium-iron-magnesium- chloride solution during pyrohydrolysis." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102490.
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Industrial experience has revealed that when used to treat multi-component metal chloride waste liquors, existing fluidized bed acid regeneration facilities are not as efficient as when employed for the pyrohydrolysis of conventional iron chloride solutions (i.e. waste pickle liquor). As a result, experimental studies and thermochemical modelling were performed to characterize the transformation of a saturated Al-Fe-Mg-Cl solution at 105°C, after it is injected into a reactor at 850°C. Efforts were geared toward defining the sequence of reactions that take place as the liquor gradually transforms into oxides.C, after it is injected into a reactor at 850°C. Efforts were geared toward defining the sequence of reactions that take place as the liquor gradually transforms into oxides.C, after it is injected into a reactor at 850°C. Efforts were geared toward defining the sequence of reactions that take place as the liquor gradually transforms into oxides.C, after it is injected into a reactor at 850°C. Efforts were geared toward defining the sequence of reactions that take place as the liquor gradually transforms into oxides.Upon completing a comprehensive literature review, testwork was initially performed with a simplified experimental set-up to study the physical behaviour of the chloride solution as it is exposed to a static bed of oxides at 850°C, and ultimately identify the various phases of the transformation process. Subsequently, controlled evaporative crystallization experiments were conducted under pseudo-equilibrium conditions to define the McClx·yH 2O precipitation path that takes place during the H2O evaporation phase and to determine whether the chlorides precipitate independently or as complex compounds. Further experiments were performed in a fully instrumented tube furnace to elaborate on the nature of the reactions (dehydration and/or pyrohydrolysis) that take place after all of the water in the starting solution has evaporated (i.e. T=300°C+).
In an effort to assist with the interpretation of the experimental results, thermochemical modelling was performed to predict the equilibrium phase assemblages that could occur during the transformation of the saturated Al-Fe-Mg-Cl solution, at reaction temperatures of 200°C+.
The research study at hand has shown that when the saturated Al-Fe-Mg-Cl solution at 105°C is exposed to fluidized bed pyrohydrolyzer operating conditions at 850°C, the following sequence of events take place: (1) rapid solvent H2O evaporation (i.e. vigorous boiling) and onset of solid metal chloride precipitation. (2) slurry densification due to a gradual increase in crystal content (i.e. AlCl·6H2O, FeCl2 ·xH2O, and MgCl2·xH2O, where x = 2 or 4). (3) hydrated crystal drying and onset of pyrohydrolysis (i.e. thermal decomposition of McClx·yH2O). The same holds true for the high temperature hydrolysis of typical waste pickle liquors (i.e. primarily FeCl2 solution).
The crystallization studies revealed that when the Al-Fe-Mg-Cl solution is allowed to gradually evaporate at 105°C,.AlCl3·6H 2O precipitates when 15% of the solvent water evolves from the liquor, followed by FeCl2·xH2O and MgCl2·xH 2O (where x = 2 or 4) at 26 and 41% evaporation, respectively. Ferric chloride remains in solution even after 54% of the water has been driven from the liquor. The latter result suggests that higher ferric concentrations in the reactor feed are more than likely to favour an increase in the quantity of liquor entrainment by the fluidizing gases and therefore lead to lower process efficiencies. Dedicated pyrohydrolysis experiments, with a simulated reactor atmosphere (gaseous, not dynamic), have shown that excluding kinetic effects, the transformation of the Al-Fe-Mg-Cl solution occurs primarily over the 300 to 600°C temperature range.
Thermochemical modelling revealed that with the exception of AlCl 3·6H2O hydrolysis, the majority of the reactions taking place as the saturated Al-Fe-Mg-Cl liquor is introduced into and eventually reaches 850°C are governed by either reaction kinetics or diffusion. Furthermore, the resulting phase assemblage at any given temperature was predicted to vary significantly with oxygen potential. A liquid chloride phase (including molten salt), other than the feed liquor, was not predicted to form at any temperature (i.e. 200°C or above) under the range of oxidizing or reducing conditions considered.
The findings of this research were quite useful in identifying the means for improving the performance of a commercial fluidized bed pyrohydrolyzer for a spent chloride liquor containing the said species.
9
Deards, Nicola. "Recrystallisation nucleation and microtexture development in aluminium-iron rolled alloys." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259602.
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Sjöstedt, Carin. "Iron and aluminium speciation in Swedish freshwaters : Implications for geochemical modelling." Doctoral thesis, KTH, Miljögeokemi och ekoteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94528.
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Speciation governs transport and toxicity of trace metals and is important to monitor in natural waters. Geochemical models that predict speciation are valuable tools for monitoring. They can be used for risk assessments and future scenarios such as termination of liming. However, there are often large uncertainties concerning the speciation of iron and aluminium in the models, due to the complicated chemistry of these metals. Both are important in governing the speciation of other metals, due to (i) their capacity to form minerals onto which metals can adsorb and (ii) their ability to compete for binding sites to natural organic matter (NOM). Aluminium is also potentially toxic and is therefore closely monitored in acidified freshwaters. In this study different phases of iron in Swedish lakes were characterised. This required a good method for preconcentrating the iron colloids. A new method was developed in this thesis that uses an anion-exchange column to isolate the iron colloids prior to characterisation with extended X-ray absorption fine structure (EXAFS) spectroscopy. Iron was present as ferrihydrite in particles but was also strongly monomerically complexed to NOM in two Swedish lakes. Based on the results an internally consistent process-based geochemical equilibrium model was presented for Swedish freshwaters. The model was validated for pH (n = 9 400) and inorganic monomeric aluminium (Ali) (n = 3 400). The model could simulate pH and Ali simultaneously, and be used for scenario modelling. In this thesis, modelling scenarios for decreases and complete termination of liming are presented for the 3 000 limed Swedish lakes. The results suggest that liming can be terminated in 30 % of the Swedish lakes and decreased in many other lakes.QC 20120919
11
Richmond, Nicola Claire. "Computer simulation study of iron, aluminium and manganese in mantle silicates." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313690.
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Zayer, Nadhum Kadhum. "Magnetic and transport properties of sputtered iron-aluminium films under vacuum." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/21526.
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Sputter deposition is one of the vapour quenching methods used to produce alloying compounds in thin film form. The alloying compounds produced by this method have a chemically homogeneous, non-equilibrium structure which is dill'erent from that of alloys produced by solid quenching, liquid quenching, or mechanical alloying methods. In the present investigation the Fe 1-:x.A1x alloy thin films were prepared using multisource magnetron sputtering. The samples were deposited onto a water cooled substrate and their thickness was kept constant at t- 300nm. To investigate the effect of the deposition parameters on the properties of the films, the samples were deposited at various argon gas pressures PAr I, 3, or 4 mtorr. The effect of gas pressure is consistent with the thermalization of the deposited material by collisions with gas atoms in the chamber. The composition range of the samples varied from pure iron to pure aluminium. The composition, structure and morphology of the films was obtained using Transmission Electron Microscopy (TEM). X-ray diffraction patterns were also used to obtain the structure of the films. Structure analysis showed that a bcc crystalline structure was obtained in samples of composition range x= 0 to - 50%, an amorphous structure in samples of composition range x- 55% to - 83%, and a fcc crystalline structure in samples of composition range x- 85% to 100%. These composition ranges are affected by altering the deposition gas pressure. The morphology of the deposited films was observed to be affected by the deposition gas pressure. The samples deposited at low gas pressure Par=1 mtorr consist of a fibrous structure with densely packed boundaries, while the samples deposited at high gas pressure Par=4 mtorr consist of columnar structures separated by open boundaries. Room temperature resistivity measurements show a drop in resistivity in the composition range x- 30% to 50%. This drop is thought to be due to the formation of chemically ordered Fe3Al and FeAI compounds. Also the resistivity increases with increasing argon gas pressure. The effect of altering the argon gas pressure is to change the morphology of these alloys, and this has a significant effect on the magnetic properties. The effect of annealing on the magnetisation and morphology was also studied in the samples. A low temperature resistivity measurement system was constructed. A closed cycle helium refrigerator, which provided a working temperature range of T= l5°K to 3000K was used for the cooling process. The resistivity measurements revealed three distinct characteristics dependent on composition :- 1. x= 0 to 46%: The samples in this range exhibit a metallic behaviour, with the samples in the composition range x= 27% to 46% showing a resistivity minimum at low temperature which is thought to be due to spin glass formation. 2. x= 48% to 83%: These samples have a semiconductor or metallic glass-like behaviour. 3. x= 85% to 100%: These samples show a metallic behaviour. The above properties are associated with the change in the structure of the fiIrns as the composition varies. A computer controlled AC susceptometer was designed and constructed to measure the AC susceptibility of the samples in the temperature range T= 20 OK to T= 300 OK. A closed cycle helium refrigerator was used to provide the cooling process. The AC susceptibility measurements for the samples with resistivity minima show a sharp peak at low temperature which confirms the presence of spin glass in these samples at low temperature. The results of magnetic and transport properties can be related to the structure and morphology of the filrns. The results have been compared with those obtained from bulk samples with the same composition.
13
Jansen, Boris. "The mobility of aluminium, iron and organic matter in acidic sandy soils." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/70962.
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Tash, Mahmoud. "Effect [sic] des paramètres métallurgiques sur le comportement d'usinage des alliages 356 et 319 (étude de forage et de taraudage) /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2005. http://theses.uqac.ca.
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15
Fox, P. "The effect of minor additions on the oxidation of an iron-aluminium alloy." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480511.
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Ayeni, Olutoyosi Olaide. "Growth responses within the Genus Cyperus exposed to aluminium and iron in hydroponics." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2430.
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Thesis (DTech (Environmental Health))--Cape Peninsula University of Technology, 2016.Generally, aluminium (Al) is required as a micronutrient by plants. The metabolism of Al within the plant can exert a number of effects within the plant. These include: interfering with cell division in both root tips and lateral roots, increasing cell wall rigidity, maintaining the correct cellular redox state, as well as the various other physiological and growth responses. Al is one of the most abundant elements in the earth’s crust and becomes toxic in many plants when the concentration is greater than 2-3 ppm, where the soil has a pH<5.5. Iron (Fe) is an equally important element, and the toxicity of this metal possesses constraints primarily on wetland plants growing in acidic soils that have high reducible iron content. The impact of metal toxicity (Al and Fe) requires an understanding of many aspects related to Al and Fe uptake, transport and distribution by plants in wetland ecosystems. In this study, three species of Cyperus viz. Cyperus alternifolius, Cyperus prolifer and Cyperus textilis were used to carry out phytotoxicity tests to monitor xenobiotic substances.
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Syahril. "Effect of ternary additions and thermomechanical treatments on the properties of Fe-11wt% Al alloys." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325578.
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Lorentsen, Odd-Arne. "Behaviour of nickel, iron and copper by application of inert anodes in aluminium production." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-68.
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A thorough investigation was performed on the behaviour of Ni, Fe and Cu oxides dissolved in cryolite melts, and the solubility of these species was measured as a function of alumina content, NaF/AlF3 molar ratio (CR) and temperature. Predominance area diagrams showing the solid phases containing Ni, Fe and Cu, respectively, as a function of the partial oxygen pressure and the alumina activity at 1020 oC were constructed. These diagrams were based on present emf and solubility measurements.
The interpretations of the solubility measurements for the oxides of Ni and Fe gaveconclusive and consistent results. The oxides of Ni and Fe exhibit decreasing solubility with decreasing temperature and with increasing alumina concentration. The Ni(II) concentration decreased from 0.32 wt% in cryolite to 0.003 wt% in alumina-saturated melts, while that of Fe(II) decreased from 4.17 to 0.32 wt% in similar melts. FeO and NiO are stable solid phases at low alumina concentrations, while FeAl2O4 and NiAl2O4 are stable at high concentrations. The alumina concentrations corresponding to the points of coexistence between FeO and FeAl2O4 and between NiO and NiAl2O4 were determined to be 5.03 and 3.0 wt% Al2O3, respectively, corresponding to the following Gibbs energy of formation from the oxide compounds,∆G0fNiAl2o4 = –28.6 ± 2 kJ/mol and ∆G0f FeAl2O4 = –17.6 ± 0.5 kJ/mol.
The solubilities of FeAl2O4 and NiAl2O4 as a function of the CR were investigated in alumina-saturated melts at 1020 oC. For both compounds a maximum solubility was found at CR ~5, being 0.008 wt% Ni(II) and 0.62 wt% Fe(II). The results are discussed with respect to the species present in solution. Both Fe(II) and Ni(II) dissolve as fluorides with different numbers of associated “NaF’s”. Ni(II) seems to form Na3NiF5 in melts with molar ratios 2 to 12, while Fe(II) is present as NaFeF3 in acidic (CR 3–10) melts and as Na3FeF5 and probably some Na4FeF6 in basic melts (CR > 3).
The solubility of both Cu oxidation states Cu(I) and Cu(II) decreases with decreasing temperature. The solubilities of Cu(I) initially decreased with increasing alumina concentration, showing a minimum at a certain alumina concentration followed by an increase. The solubilities were 0.36 wt% Cu(I) and 0.92 wt% Cu(II) in cryolite, and 0.30wt% Cu(I) and 0.45 wt% Cu(II) in alumina-saturated cryolite at 1020 oC.
At 1020 oC the solubilities of Cu2O and CuO were little influenced when changing the CR from 3 to 8 in alumina-saturated melts (~0.30 wt% Cu(I) and ~0.45 wt% Cu(II)), but there was an upward trend for CR < 3. Solubility measurements for CuO in alumina-saturated melts at CR 3.0 to 1.2 clearly showed that the saturation concentration is dependent on both temperature and melt composition.
Copper ions in solution show a complex behaviour, since they form fluorides and oxycomplexes simultaneously. The extent of co-existence of Cu(I) and Cu(II) in the same melt is also considerable, and it is depending on the alumina activity in the melt. According to thermodynamics the stable copper oxide phases at high alumina activities are the aluminates CuAlO2 and CuAl2O4. However, no clear changes in the solubilities were found for the points of coexistence between Cu2O and CuAlO2 and CuO and CuAl2O4, respectively, as was the case for Ni(II) and Fe(II). Although there are uncertainties regarding the thermodynamic data available for the formation of copper aluminates, models for the dissolution mechanisms and for the species present in the melt are suggested. Cu(I) seems to form mainly CuF at low alumina contents, while Na5CuO3 dominates at higher alumina concentrations. Likewise, Cu(II) seems to form CuF2, but the concentration of CuF2 decreases with increasing alumina content. The species that gave the best fit for the cupric oxy-complexes was Na16CuO9, and the amount increased with increasing alumina content.
Cermet anodes were prepared with a NiFe2O4-based oxide phase mixed with a ~20 wt% copper-rich metal phase. The electrical conductivity for these materials was measured as a function of temperature, showing semiconductor behaviour in the temperature range from room temperature to 1050 oC. The highest electrical conductivity measured was ~30 S/cm at 1000 oC, which is on the low side for use as an anode material for aluminium production.
Three cermet anodes were tested by electrolysis for 48 hours. After the experiments the anodes were examined with SEM. There was no metal phase present in the outer 100 µm of the anode, not even pores were observed that could indicate where the metal grains had been. A copper-rich phase was found in one case ~2 mm from the outer surface, and it is believed that copper diffuses out of the anode.
The cermet anodes dissolved slowly in the electrolyte during electrolysis. The steady state concentrations of Fe and Cu in the electrolyte were below the saturation concentrations, while the concentration of Ni was 3 - 4 times above saturation. The dissolution of the anode does not fit a first order mass-transport model, but it can probably be explained by a controlled dissolution mechanism with some additional disintegration/spalling of the anode material. Further work is needed to draw a firm conclusion. In general, correct solubility data for the anode constituents are needed to make a proper evaluation of various anode materials. Perhaps the first order mass-transport model agrees for some materials, but based on the present results it seems untenable for cermet materials made of NiFe2O4 with a copper-rich metal phase.
The solubilities of the oxides of Ni(II) and Fe(III) are very low for the alumina-saturated melt used during electrolysis, which make them promising candidates for inert anodes. However, if nickel aluminate, which is an insulator, is formed and deposited on the anode surface, it is a cause of concern. Fe(II) aluminate is not expected to form on the anode surface, since Fe(III) is the stable oxidation state in the presence of oxygen gas. However, solid Fe(II) aluminate may be formed in the bulk of the electrolyte where the partial oxygen pressure is lower.
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Boutorabi, S. M. A. "The austempering kinetics, microstructure and mechanical properties of spheroidal graphite unalloyed aluminium cast iron." Thesis, University of Birmingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520795.
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The effect of austempering processing variables on the transformation kinetics, microstructure and mechanical properties of the Fe-C-AI family of spheroidal graphite cast irons, in which the silicon is below 0.2wt% has been investigated. These alloys are described as SO Al cast irons. In the preliminary experiments the spheroidisation and inoculation treatments for SO Al were developed and the microstructure and tensile properties in the as cast and normalised SO Al cast iron at 2.2 and 3.2% of Al examined. The results show that the sequence of spheroidisation of SO Al iron differs significantly from those observed in SG Si iron. Whilst the treatment to introduce some Mg into the melt is required in both irons to alter the growth habit of graphite from flake to spheroidal, the behaviour of the irons towards the subsequent inoculation with various inoculating alloys is quite different. A wide range of mechanical properties of SG Al irons can be obtained, similar to SG Si irons, in the as cast or heat treated conditions. The effects of austenitizing temperatures of 850, 900 and 950°C, austempering temperatures of 300 to 450°C and austempering times of 5 to 300 minutes on impact and tensile properties have been investigated. X-ray diffraction has been used to determine the volume fraction, lattice parameter and carbon content of retained austenite and bainitic ferrite produced under different austempering conditions. Optical and scanning electron microscopy were used to analyse the microstructure. It has been shown that the basic mechanisms for the isothermal transformation of austenite to bainite are essentially similar to those of austempered SO silicon cast irons for both lower and upper bainite. This can be attributed to the strong graphitising effect of aluminium which delays the formation of transformation carbides. However, the higher carbon contents of retained austenite in SG Al iron show the stronger carbide inhibiting characteristics of aluminium compared with those of silicon. The first stage starts with the nucleation of bainitic ferrite from the grain boundaries and adjacent to the graphite nodules. The second stage in upper bainite fonnation is the growth of ferrite, during which carbon diffusion occurs ahead of the ferrite-austenite interface thus enriching the surrounding austenite. This is followed in the third stage by carbide precipitation in the high carbon retained austenite. In lower bainite fonnation the nucleating ferrite is supersaturated with carbon, and carbide precipitation occurs inside ferrite plates. The results show that the rate of fIrst stage transfonnation is higher in SO Al than in the corresponding SO Si iron, and the high carbon retained austenite has a longer life time with a high carbon content. Increasing the austempering temperature was shown to increase structural coarseness and retained austenite content, leading to reduced strength and hardness and improved impact properties and ductility. Retained austenite produced in austempered SO Al iron showed more stability at a high austempering temperature of 450°C, compared to SO Si iron. This was attributed to the graphitising potential of aluminium which suppresses the formation of carbide at that temperature. Austenitizing temperature was found to control the carbon content of both the matrix and of the retained austenite. Increasing the austenitizing temperature was shown to increase the matrix carbon content and to slow the bainitic reaction. Microstructures obtained at higher austenitizing temperature revealed two types of retained austenite: one with a film morphology and the other in a blocky form surrounded by ferrite growing in different directions. The length of bainitic ferrite appears to increase with austenitizing temperature. Austenitizing temperature had a greater effect on hardness in the lower bainitic region and on impact values in the upper bainitic region. The results obtained show that the controlling austempering variables for an SO Al iron of a given starting composition and microstructure are closely similar to those of SO Si iron. The transformation mechanisms are also similar, but the transformation kinetics differ and, to a small extent, microstructural differences give rise to differences in properties between the two types of irons.
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Hu, Sichun. "Investigation and laboratory tests of sub-economic aluminium resources in China." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/436.
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China, the largest aluminium producer, is seriously lacking of reserves at the present and in the future. However, there are a huge amount of sub-economic aluminium resources (high iron diasporic, low A/S and high iron gibbsite and high sulfur diasporic bauxite), and potassic sandy shale suitable for the extraction of aluminium and the production of potassium and silicon fertilizers if proper metallurgical processes are developed. This study aims to investigate the sub-economic aluminium resources through investigation and identify the right technologies through laboratory tests for metal extraction and utilization of the by-products of K-feldspar sandy shale. The investigation of the sub-economic aluminium resources includes field and site visits and data collection and collation. A series of laboratory scale tests were carried out for different types of bauxite and potassic sandy shale, which includes initial try tests and formal laboratory experiments for optimization of the processes and procedures, and crop planting tests for use of potassium and silicon fertilizers. The successful laboratory tests (technologies) in this study were optimized and proved to be effective. The results showed: 1) Medium temperature metallization roasting and then magnetic separation, and gas reduction metallization roasting and then magnetic separation are effective for processing of the high iron diasporic bauxite; 2) Dry magnetic separation, wet magnetic separation and medium temperature magnetization roasting and then magnetic separation are not effective for processing of the high iron diasporic bauxite; 3) Digestion at atmospheric conditions and high caustic alkali concentration is effective for processing of low A/S and high iron gibbsite bauxite; 4) Desulfurization flotation and desulfurization with barium aluminate are both effective for processing of the high sulfur bauxite. However, each of these methods have their own advantages and disadvantages and must be evaluated; and 5) The soda-lime sintering process is suitable for processing of the Linzhou potassic sandy shale. The aluminium and potassium are extracted and the silicon residues can be used for silicon fertilizer. The results of this study help solve the problem of aluminium reserve shortage. They also open a new way for integrated utilization of other aluminium resources including potassic sandy shale.
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Potter, Hugh 1967. "A study of the retention of heavy metals by amorphous iron-aluminium oxides and kaolinite /." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36683.
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Amorphous iron-aluminium oxides are ubiquitous in the environment and control the availability of heavy metals (Pb, Cu). Oxide physicochemical properties are affected by the proportion of Fe and Al, the Fe/Al ratio. Five amorphous oxides containing Fe and/or Al were synthesised: "Fe" (only Fe); "3FeAl" (3 moles Fe per mole Al, Fe/Al = 3); "FeAl" (Fe/Al = 1); "Fe3Al" (Fe/Al = 0.3); "Al" (only Al). Kaolinite clay was also investigated along with kaolinite to which Fe-Al oxides had been added.The effect of Fe/Al ratio on these physicochemical properties was studied: (1) Specific surface area---EGME retention; (2) pH-dependent cation and anion exchange capacity---Ca(NO3)2 saturation; (3) Particle size density---sieving, pipette methods; (4) Surface charge density---potentiometric titrations.
The Fe/Al ratio influenced the specific surface area: Fe and 3FeAl had significantly greater surface areas than Fe3Al and Al; FeAl exhibited the maximum surface area. The cation exchange capacity increased rapidly above pH 5, with Fe > 3FeAl > Al > Fe3Al > FeAl at pH 6 to 7. Surface charge density of low Fe/Al oxides was more sensitive to pH changes implying ≡AlOH surface hydroxyl groups are more easily protonated and de-protonated than ≡FeOH species. An open (porous) structure of loosely linked small particles was proposed with SO42- anions forming bridges between Al3+ and Fe3+ ions during oxide precipitation while inhibiting extensive crystal growth.
Pb and Cu retention was measured using 24 hour batch suspension tests with varying pH and contaminant concentrations (0.5 to 25 mmol/L). Higher Fe/Al ratio oxides retained more Cu and Pb at all pH values. Cu retention (0.5 to 5 mmol/L) and Pb retention (all concentrations) followed Fe > 3FeA > FeAl > Fe3Al > Al but at 25 mmol Cu/L, only Fe accumulated more Cu. However, low Fe/Al ratio oxides preferentially sorbed Cu over Pb from multi-contaminant solutions. Adsorption rather than bulk precipitation was the dominant accumulation mechanism. Geochemical modelling suggested surface precipitation occurred at higher contaminant concentrations.
Adding oxides to kaolinite significantly increased the clay's specific surface area, surface charge density and contaminant retention capacity; higher Fe/Al ratio oxide-amended clays retained more Pb and Cu.
Amorphous Fe-Al oxides substantially enhance heavy metal accumulation by soils with higher Fe/Al ratio oxides being particularly effective.
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Potter, Hugh. "A study of the retention of heavy metals by amorphous iron-aluminium oxides and kaolinite." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0029/NQ64646.pdf.
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Amiriyan, Mahdi. "Development of ceramic reinforced iron aluminide based composite coatings for wear resistant applications." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/35012.
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Les composés intermétalliques Fe₃Al et leurs revêtements composites sont des matériaux structuraux potentiels pour des applications tribologiques. Parmi les composites, ceux obtenus par broyage mécanique à haute énergie possèdent plusieurs avantages, en particulier une fabrication rentable. Le broyage à billes à haute énergie permet également une large gamme de fraction volumique des particules de renforcement. Dans cette recherche, Nous avons préparé des revêtements composites à matrice d'aluminiure de fer, basés sur la composition chimique de Fe₃Al avec des particules de renforcement de TiC et de TiB₂ en utilisant un broyeur à billes à haute énergie et déposé par la technique HVOF (High Velocity Oxy Fuel). L'effet des paramètres de traitement tels que la durée du broyage et le traitement thermique subséquent sur les la matière première destinés à la projection par HVOF a été étudié. Les paramètres de traitement ont joué des rôles importants sur la poudre composite et par la suite sur la microstructure, les propriétés mécaniques et tribologiques des revêtements. Le but de la première phase expérimentale de ce travail était d'étudier l'effet des particules de TiC in situ sur la microstructure, le comportement mécanique et tribologique des revêtements de Fe₃Al déposés par HVOF. Dans cette étape, des poudres composites Fe₃Al / TiC avec différentes quantités de carbure de titane ont été produites par broyage à haute énergie. Un mélange de Fe₃Al-Ti-C a été broyé pendant 6 h suivi d'un traitement thermique à 1000 °C pendant 2 h sous vide poussé. Des revêtements composites d'aluminure de fer renforcés au TiC in situ ont été préparés pour améliorer la dureté Vickers et la résistance à l'usure des intermétalliques de Fe₃Al. Les revêtements composites consistent principalement en une phase de TiC uniformément dispersée dans des lamelles de la matrice de Fe₃Al. Les revêtements composites ont montré une dureté Vickers croissante avec l’augmentation de la quantité de TiC, allant jusqu'à 70 % en moles de TiC. La résistance à l'usure par glissement à sec des revêtements a été augmentée avec l'addition de particules de TiC formées in situ. Les revêtements composites de Fe₃Al déposés par HVOF avec des renforts en TiC de 50 % et 70 % en moles présentaient une excellente résistance à l'usure par glissement. Le mécanisme d'usure dominant de ces revêtements était l'abrasion et l'oxydation. Dans une autre étape de ce travail, des poudres composites de Fe₃Al-TiB₂ avec deux quantités différentes de borure ont été produites par le dépôt par high Velocity Oxy Fuel (HVOF) sur un substrat en acier. Les revêtements composites consistaient principalement en une phase de TiB₂ pré-synthétisée et uniformément dispersée dans des lamelles de la matrice de Fe₃Al. Il a été montré qu'en augmentant la fraction volumique du TiB₂, la dureté Vickers et la résistance à l'usure par glissement des revêtements contre le contre-corps en alumine (6,33 mm de diamètre) étaient augmentées. L'augmentation de la résistance à l'usure était censée être liée à l'amélioration de la dureté, qui à son tour est due à la présence de particules de TiB₂ dans la matrice Fe₃Al. Le taux d'usure de glissement des revêtements a augmenté pour atteindre un maximum lorsque la vitesse de glissement augmente, puis il a diminué avec l'augmentation supplémentaire de la vitesse de glissement. Les analyses chimiques des surfaces usées ont montré que des vitesses de glissement plus élevées entraînent une oxydation plus élevée de la surface, probablement en raison de la température locale plus élevée. Une telle couche d'oxyde semble agir comme une barrière entre deux corps coulissants, diminuant ainsi le taux d'usure.Fe₃Al intermetallic compounds and their composite coatings are potential structural materials for tribological applications. High-energy ball milled powders possess several advantages, especially cost-effective fabrication and lower cost of reinforcement. High-energy ball mill also allows for a wide range of reinforcement volume fraction. In this research, Iron Aluminide matrix composite coatings based on Fe₃Al chemical composition with TiC and TiB₂ particles were prepared using a high-energy ball mill and deposited via the High Velocity Oxy Fuel (HVOF) technique. The effect of processing parameters such as ball milling duration and subsequent heat treatment soaking time and temperature on the phases of products as a feed stock for the HVOF gun was studied. The processing parameters played important roles on the microstructure, mechanical and tribological properties of the coatings. The aim of the first experimental stage of this work was to study the effect of in-situ TiC particles on microstructure, mechanical and tribological behavior of HVOF deposited Fe₃Al coatings. In this stage Fe₃Al/TiC composite powders with different carbide quantities were produced via high-energy ball milling of Fe₃Al-Ti-C system for 6 h followed by heat treatment at 1000 °C for 2 h under high vacuum. In-situ TiC-reinforced iron aluminide composite coatings were prepared to improve the Vickers hardness and wear resistance of Fe₃Al intermetallics. The composite coatings mainly consist of a TiC phase uniformly dispersed within lamellae of the Fe₃Al matrix. The composite coatings showed increasing Vickers hardness with increasing TiC content up to 70 mol% TiC. The dry sliding wear resistance of coatings was increased with the addition of in-situ formed TiC particles. HVOF deposited Fe₃Al composite coatings with 50 and 70 mol% TiC reinforcements exhibited excellent sliding wear resistance. The dominant wear mechanism in those coatings was abrasion and oxidation. In another stage of this work Fe₃Al-TiB2 composite powders with two different boride quantities were produced by the high Velocity Oxy Fuel (HVOF) spray deposition on a steel substrate. The composite coatings mainly consisted of a TiB₂ phase uniformly dispersed within lamellae of the Fe₃Al matrix. It was shown that by increasing the volume fraction of TiB₂ both the Vickers hardness and sliding wear resistance of the coatings against alumina counterbody (6.33 mm in diameter) were increased. The increase of wear resistance was believed to be related to the hardness enhancement, which, in turn, is due to the presence of TiB₂ particles within the Fe3Al matrix. The sliding wear rate of the coatings increased to reach a maximum as the sliding speed increases, and then it decreased with further increase of the sliding speed. The chemical analyses of the worn surfaces showed that higher sliding speeds result in higher oxidation of the surface, most likely due to the higher local temperature. Such an oxide layer seems to act as a barrier between two sliding bodies, thus decreasing the wear rate.
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Farhadi, Cheshmeh Morvari Gholamali. "Les effets des éléments de trace sur les caractéristiques des alliages de type 6XXX pour les applications automobiles /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1999. http://theses.uqac.ca.
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Doggaz, Amira. "Déferrisation des eaux par procédé d’électrocoagulation : étude des phénomènes physico-chimiques et réactionnels impliqués." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0171.
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La demande croissante en eau nécessite l’exploitation de certaines sources ferrugineuses. Cependant la présence du Fe(II) dissous induit des problèmes d’ordre esthétique et organoleptique. L’électrocoagulation (EC), en tant que procédé substitut de la méthode conventionnelle, a prouvé son efficacité pour l’élimination du fer. En revanche, le mécanisme de déferrisation par EC reste peu connu et non maitrisé. La difficulté de l’étudier provient de l’intervention simultanée de plusieurs phénomènes. Les travaux de cette thèse ont de ce fait pour objectif d’apporter une meilleure compréhension du mécanisme d’élimination du Fe(II) par EC. Ainsi, différentes méthodes d’élimination du fer et des techniques d’analyses du liquide et du solide ont été exploitées. Au moyen d’une unité à recirculation forcée de la solution avec des électrodes en aluminium, la technique d’EC parvient à éliminer 97% d’une solution de 25 mg/L du fer. La quantité optimale d’énergie est de 0,21 kWh/m3. Des essais en milieu anoxique ont montré que la réduction du fer ionique par adsorption sur les flocs de Al(OH)3 est faible (18%). Par oxydation-précipitation à pH 6,5, le Al(OH)3 catalyse la réaction d’oxydation. Cet effet est plus prononcé en présence des ions chlorure qu’en ions sulfate. La spéciation associée à la modélisation cinétique ont permis d’apporter des explications sur le mode d’action de ces ions. Cependant, les expériences par EC en milieux anoxique et oxygéné montrent que la part de l’oxydation dans l’élimination du fer est négligeable pour les pH de travail. Les calculs thermodynamiques au voisinage des électrodes permettent de proposer la précipitation de Fe(OH)2, comme mécanisme prédominant d’élimination du fer par EC. La présence des carbonates réduit la performance du système par la réduction de la précipitation de Fe(OH)2 suite à la diminution du pH local et le Fe2+ libre par formation des complexes du Fe(II)Water scarcity in some areas requires the exploitation of some ferruginous sources. However, the presence of Fe(II) induces aesthetic and organoleptic problems. The electrocoagulation (EC), as an alternative process of the conventional method, proved its efficacy for iron removal. Nevertheless, the iron removal mechanism in EC process remains unstudied and still unclear. The simultaneous involvement of several phenomena makes difficulties to study the system. This thesis aims to provide a better understanding of the mechanism of Fe(II) removal by EC and to highlight the phenomena that are most likely. Thus, different methods of iron removal and liquid and solid analysis techniques have been used. By means of a forced recirculating unit, EC's technique with aluminum electrodes reduce the dissolved iron of 25 mg Fe(II)/L - solution by about 97% with an optimum energy amount of 0,21 kWh/m3. Anoxic experiments showed that the reduction of ionic iron by adsorption on Al(OH)3 flocs is negligible (18%). Oxidation-precipitation experiments showed that at work pH 6,5, Al(OH)3 catalyzes the oxidation reaction. The catalytic effect is more pronounced in the presence of chloride ions than in sulfate ions. Fe(II)-speciation associated with kinetic modeling have allowed to explain of the mode by which these ions acts on the oxidation reaction kinetics. However, EC experiments in anoxic and oxygenated media show that the proportion of oxidation in iron removal is insignificant for work pH. Thermodynamic calculations allowed to propose the precipitation of Fe(OH)2 in the vicinity of the cathode as the predominant mechanism of iron removal by EC. The presence of carbonates affects the performance of the process by reducing the precipitation of Fe(OH)2; this was attributed to the decrease of the local pH and the free Fe(II) amount by Fe(II)-complexes formation
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Khalifa, Waleed. "Rôle des inclusions dans la germination de la phase a-aluminium des intermétalliques contenant du fer dans le coin riche en alumimium du système ternaire Al-Si-Fe /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2003. http://theses.uqac.ca.
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Glocheux, Y. "Investigations on iron and aluminium oxides and oxyhydroxides based sorbents for the removal of arsenic from groundwater." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675463.
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This thesis presents investigations on the use of various iron and aluminium oxides, and oxyhydroxides based sorbents for the removal of arsenic from groundwater via adsorption processes. Three main types of materials were employed: (i) a natural ore and an industrial by-product; (ii) organised mesoporous silicas (OMS) coated with iron and aluminium, and: (iii) metal oxyhydroxides produced from industrial coagulants solutions (FAS(OH)s). The synthetized materials were optimised with respect to adsorption capacity and all the sorbents were fully characterised. The OMS were coated with various ratios of Fe and AI oxides with a view to tailoring the As(III)/As(V) selectivity of the adsorbents. The effects of pH, arsenic speciation and concentration. and adsorbent dosage on the adsorption of arsenic were investigated in a series of batch experiments as well as the different adsorption mechanisms. A kinetic investigation was undertaken with the effect of particle size on the adsorption process and the diffusion of the As species within the solid matrix of the absorbents were investigated. The most promising materials with regard to adsorption capacity were then employed in small scale columns, for evaluation of performance in a continuous process. Several aspects from these investigations were considered and discussed with regard to the potential use of the materials in full-scale fixed bed adsorption units. First the effect of common dissolved ions on the adsorption efficiency of the materials was studied and a reconstituted groundwater was used for comparison purposes. The regeneration of saturated adsorbents using various chemicals was investigated. In a further study, the metal oxyhydroxide powder adsorbent was agglomerated into a granular material and used in subsequent adsorption experiments. Finally, a full scale adsorption unit was designed employing the optimal adsorbent material, which may result in a 50 % smaller footprint unit when compared to existing technologies.
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Bernauer, Josef [Verfasser], and von Wangelin Axel [Akademischer Betreuer] Jacobi. "Aluminium and Iron Catalysts as sustainable Alternatives in Synthetic Processes / Josef Bernauer ; Betreuer: Axel Jacobi von Wangelin." Regensburg : Universitätsbibliothek Regensburg, 2021. http://d-nb.info/1237105803/34.
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Hearn, Nikol Anuschka. "An economic impact analysis of mineral beneficiation in Kwazulu-Natal's iron and steel and aluminium value chain." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15760.
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This paper examines mineral beneficiation within the aluminium and iron & steel industries in Kwazulu-Natal and the associated value chains. Multiplier analysis is used in conjunction with the provincial social accounting matrix to determine the knock on effects of increased beneficiation, exploring the relevant impact of backward linkages. The multipliers created by both direct and indirect stimulation in the downstream industries are examined and the impacts of beneficiation on economic and welfare indicators are assessed. The key findings of the study are that the net effect on regional production is more than double the value of the initial stimulation for each of the considered sectors in the value chain. Moreover, job creation becomes evident when demand increases and that much of this employment go to the previously disadvantaged. There are however relevant drawbacks in terms of constrained electricity supply and significant leakages created by imports
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Smillie, Matthew John. "Casting and Analysis of Squeeze Cast Aluminium Silicon Eutectic Alloy." Thesis, University of Canterbury. Mechanical Engineering, 2006. http://hdl.handle.net/10092/1086.
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Squeeze casting is the practise of solidifying metals under mechanically applied pressure via a slow displacement of a die volume. It has been shown that squeeze casting enhances the mechanical properties of cast metals. Research into other high integrity casting processes has shown that using techniques that enhance melt quality can further increase the mechanical properties. Therefore a bottom-tapped, bottom-fed squeeze casting machine was designed and built around a pre-existing squeeze casting die designed for uniaxial pressure application. This was used to obtain quantitative metallurgical and microstructural information on the squeeze castings produced, including the effects of common micro-alloying additions of strontium modifier and titanium modifier on the microstructure and hardness of a commercial aluminium silicon eutectic alloy. These were examined using a Taguchi design of experiments approach. It was found that squeeze casting reduced porosity and secondary dendrite arm spacing and increased hardness, and reduced or eliminated increases in porosity and secondary dendrite arm spacing associated with micro-alloying addition. The size of possibly deleterious iron-rich precipitates was reduced, and the morphology of such precipitates changed to a possibly less deleterious form without further alloy additions of manganese. It was also found that melt control and handling is essential for consistent quality of castings in the production of small volume squeeze castings, such as the ones produced in this experimental work.
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Xu, Nan Materials Science & Engineering Faculty of Science UNSW. "Corrosion behaviour of aluminised steel and conventional alloys in simulated aluminium smelting cell environments." Awarded by:University of New South Wales. School of Materials Science & Engineering, 2002. http://handle.unsw.edu.au/1959.4/18760.
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Aluminium smelting is a high temperature electrometallurgical process, which suffers considerable inefficiencies in power utilization and equipment maintenance. Aluminium smelting cell works in the extreme environments that contain extraordinarily aggressive gases, such as HF, CO and SO2. Mild steel used as a structural material in the aluminium industry, can be catastrophically corroded or oxidized in these conditions. This project was mainly concerned with extending the lifetime of metal structures installed immediately above the aluminium smelting cells. An aluminium-rich coating was developed on low carbon steel A06 using pack cementation technique. Yttria (Y2O3) was also used to improve the corrosion resistance of coating. Kinetics of the coating formation were studied. XRD, FESEM and FIB were employed to investigate the phase constitution and the surface morphology. Together with other potentially competitive materials, aluminium-rich coating was evaluated in simulated plant environments. Results from the long time (up to 2500h) isothermal oxidation of materials at high temperature (800??C) in air showed that the oxidation resistance of coated A06 is close to that of stainless steel 304 and even better than SS304 in cyclic oxidation tests. Coated A06 was also found to have the best sulfidation resistance among the materials tested in the gas mixture contains SO2 at 800??C. Related kinetics and mechanisms were also studied. The superior corrosion resistance of the coated A06 is attributed to the slow growing alpha-Al2O3 formed. Low temperature corrosion tests were undertaken in the gas mixtures containing air, H2O, HCl and SO2 at 400??C. Together with SS304 and 253MA, coated A06 showed excellent corrosion resistance in all the conditions. The ranking of the top three materials for corrosion resistance is: 253MA, coated A06 and SS304. It is believed that aluminised A06 is an ideal and economical replacement material in the severe corrosive aluminium smelting cell environment.
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Malavazi, Jefferson. "Caracterização microestrutural dos compostos intermetálicos e seu efeito no comportamento mecânico nas ligas de Al-9%Si com adições de Fe e Mn." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-17032014-151816/.
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O objetivo deste trabalho foi determinar a influência do ferro e do manganês em uma liga de alumínio com 9% de silício (% em peso). Para isto, foram elaboradas duas famílias de liga Al-9%Si: uma com os teores de 0,1%, 0,4%, 0,8% e 1,2% de Fe e uma segunda liga de Al-9%Si-0,8%Fe com teores de 0,1%, 0,4% e 0,7% de Mn. Para a realização deste estudo, foram produzidos corpos de prova de tração fundidos em coquilha, segundo a norma ASTM B108. Os corpos de prova obtidos foram tracionados para avaliação das propriedades mecânicas, em seguida, foram submetidos a uma análise microestrutural por microscopia óptica (MO) e eletrônica de varredura (MEV). As superfícies de fratura dos corpos de prova tracionados foram também observadas por MEV com a finalidade de comparar o efeito das adições de Fe e Mn. O efeito da adição crescente de Fe na liga Al-9%Si foi observado no ensaio de tração que mostrou queda tanto nos limites de resistência e de escoamento como no alongamento, decorrentes da formação da fase β-Al5FeSi que apresentou morfologia em plaquetas, interrompendo a continuidade da matriz de alumínio. Para teores abaixo de 0,4% de Fe, ocorreu um ligeiro aumento da resistência mecânica que pode ser atribuído à formação da fase α-Al8Fe2Si, que apresentou morfologia tipo escrita chinesa, que não interrompe a continuidade da matriz. Com adição de teores crescentes de Mn na liga Al-9%Si-0,8%Fe ocorreu uma elevação do limite de resistência e do alongamento, mas uma queda do limite de escoamento, quando comparados com a mesma liga sem adição de Mn. Conclui-se que esse comportamento pode ser atribuído a mudança de morfologia do intermetálico de plaquetas para escrita chinesa que intercala a matriz dúctil com a fase frágil, devido a adição do Mn.This study aims to determine the influence of iron and manganese in an aluminum alloy with 9% silicon (% by weight). Were prepared two families of alloy Al-9%Si: one with the content of 0.1%, 0.4%, 0.8% and 1.2% Fe and a second alloy of Al-9% Si-0,8%Fe content of 0.1%, 0.4% and 0.7% Mn. For this study, tensile specimens were produced in permanent mold casting according to ASTM B108. The specimens obtained were pulled for quantitative evaluation of the mechanical properties and were subjected to a qualitative metallographic evaluation. Qualitative analysis of the bodies of tensile fracture test was conducted in order to compare the effect of additions of Fe and Mn. The effect of incremental addition of Fe in the alloy Al-9% Si was observed in the tensile test that showed a decrease in both the tensile and elongation flow as resulting from the formation of β-Al5FeSi phase platelet morphology showed that interrupting the continuity of aluminum matrix. To levels below 0.4% Fe, there was a slight increase in strength can be attributed to the formation of α-Al8Fe2Si phase morphology presented in chinese script that does not interrupt the continuity of the matrix. With addition of increasing concentrations of Mn in the alloy Al-9% Si-0, 8% Fe was an increase in the tensile strength and elongation but fall of yield stress when compared to the same alloy without Mn addition. We conclude that this behavior can be attributed to a change in morphology of the intermetallic platelets to chinese writing interspersing the ductile matrix with brittle phase due to the addition of Mn.
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Vilmart, Gautier. "Détection de vapeurs d'atomes métalliques par fluorescence induite par laser (LIF) : application à la propulsion solide." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS523/document.
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Cette thèse porte sur la méthode de Fluorescence Induite par Laser (LIF) à haute cadence développée sur deux atomes métalliques (Al et Fe) utilisés comme traceurs fluorescents dans les flammes de propergols solides où ils sont naturellement présents. Deux expériences d’évaporation de l’aluminium sont mises en œuvre pour mettre au point la technique dans des conditions contrôlées sur une large gamme de pressions et températures. Un modèle théorique du processus de fluorescence appliqué à ces deux atomes est élaboré pour calculer les taux de quenching du signal avec la pression et la température. Les données collisionnelles qui sont inconnues sont prédéterminées théoriquement pour Fe et expérimentalement pour Al. Les coefficients de transferts d’énergie et d’élargissements spectraux par collisions de l’atome Al sont déterminés expérimentalement en environnement d’azote pur. Une étude du comportement du signal de Al avec l’énergie laser est effectuée pour mesurer les seuils de saturation avec les gaz N₂, Ar et He en fonction de la pression. Le modèle permet de reproduire correctement les profils temporels et spectraux avec toutefois des approximations et des limitations qui sont explicitées. Une première application de l’imagerie LIF sur Al dans une flamme de propergol solide aluminisé (10 bar et 3000 K) permet de visualiser des gouttes d’aluminium réactives et observer leur évolution dans la flammeDuring the PhD thesis, high-speed laser induced fluorescence (LIF) of two metallic atoms (Al and Fe) is presented, in order to use them as fluorescent markers in solid propellant flames, where they are naturally present. LIF measurements are first performed inside two different evaporation chambers used to generate aluminum vapors in controlled conditions over a broad pressure and temperature range. A theoretical model of the LIF process is elaborated and applied to both atoms in order to calculate the signal quenching rate as a function of pressure and temperature. Unavailable collisional data are determined theoretically for Fe and experimentally for Al. Energy transfer and collisional broadening coefficients are determined experimentally for the Al atom in pure nitrogen environment. Study of the signal level of Al as a function of laser intensity is undertaken to measure saturation thresholds in N₂, He and Ar as a function of pressure. The model is used to properly reproduce the temporal and spectral profiles, though some approximations and limitations remain. A first application of high-speed LIF imaging to the measurement of aluminum in a solid propellant flame (10 bar , 3000 K) is demonstrated. It allows us to clearly visualize reactive aluminum droplets in the flame and to follow their evolution in the flame
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Davis, Jennifer. "Closing the cycles of iron, steel and aluminium in the UK on recycling rates, scrap quality and collection of dispersed scrap." Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/843368/.
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The closure of anthropogenic substance and material cycles is a central theme in industrial metabolism and ecology. Its desirability is based on the analogy with biological nutrient cycles that are closed, as a requirement for their long-term sustainability. This thesis sets out to assess the level of closure of the UK iron, steel and aluminium cycles; i.e. three of the main structural 'nutrients' of the global industrial ecology. To investigate this a new time-dependent methodology for material flow analysis (MFA) has been developed. In sectors such as iron, steel and aluminium where the life-span of goods may be long and the life-spans differ between applications, it is vital to include a temporal dimension in the MFA; different products available as scrap entered use at quite different past times. In this analysis, residence time distribution theory, as developed in chemical engineering science, has been successfully adapted to simulate the delay of goods in use. The methodology has been applied to track the flows of iron, steel and aluminium through the UK economy. Historic information on the amounts of these metals going into different groups of goods, together with values for their estimated life-spans, have enabled modelling of the yearly release of iron/steel and aluminium scrap from the use phase in the form of end-of-life scrap. The iron and steel MFA carried out in this work shows that for 2001, the estimated release of end-of-life scrap and prompt scrap significantly exceeds the documented amount of scrap that is consumed within the country or is exported. This indicates a loss of end-of-life scrap of around 30% (corresponding to three and a half million tonnes). For aluminium, the analysis also shows that for 2001, the estimated amount of released prompt and end-of-life scrap is higher than the documented amount of recovered scrap. There is a loss of end-of-life scrap of about 20% (corresponding to 160 thousand tonnes). For both metals, a level of closure was achieved in the MFAs; i.e. modelled amounts of metal emerging from use could be largely balanced with documented amounts of metal being recycled and sent to landfill. The analysis shows that using a distribution of the life-span (as opposed to a fixed life-span) when modelling the delay of goods in the use phase is more important when the input of goods into use shows a significant increase or decrease over time. To achieve and maintain higher recycling rates of these metals it is vital to avoid build-up of alloying and contaminating elements in the scrap cycle. A model for exploring potential contamination build-up in the metal cycle has been developed in this work, which builds on the MFA methodology, incorporating the temporal dimension. It examines consequences for the composition of the metal flows depending on different future scenarios. A case study of exploring potential build-up of tin in the iron and steel cycle between 2000 and 2020 was performed to demonstrate the model. Not surprisingly, both increasing recycling rates and decreasing scrap exports leads to increases in the concentration of tin in metal products. By separating the scrap before remelting and choosing more carefully what type of scrap goes to which production, buildup can be avoided. The methodology presented here should prove useful in further exploring potential contamination in metal products and developing strategies how to avoid it. The MFA studies show there are still improvements to be made in recovering end-of-life iron/steel and aluminium scrap. Small products such as packaging stand out as a major challenge for these metals. Therefore, possible ways of collecting beverage cans were investigated in a case study of used aluminium beverage cans (UBCs). Two main issues explored included the questions: (1) Does transport intensity differ greatly between various types of collection systems, recovery rates and population density. and (2) How significant is the environmental impact of the collection stage compared to the whole life cycle of the can. Overall, the differences in environmental impacts between the collection systems (kerbside, can banks and deposit) are not considerable. Transport per collected unit increases with decreasing population density. However, in the context of the whole life-cycle of aluminium cans, the analysis of the systems shows that over a range of population density, the collection stage makes negligible contribution to en- vironmental burdens. The savings in environmental impact of recovering and recycling the cans after use far outweigh the impacts of collecting them. This very much highlights the need for functional and easily accessible recovery infrastructures for aluminium cans in the UK.
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COUTO, ANTONIO A. "Influencia do teor de cromo e de tratamentos termicos na microestrutura e no comportamento mecanico de ligas intermetalicas ordenadas a base de Fesub3 Al." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10701.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Andersson, Simon, and Johan Petersson. "Potential for Urban Mining in Norrköping : a Static Quantification of Metal in Subterranean Infrasystems." Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68929.
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As the society’s demand for metal increases, the rate of mineral extraction will do the same. This contributes to environmental implications in the form of emissions and depletion of finite natural resources. Conventional recycling is a common practice used to reduce the need for extraction of metal ore and in turn reduce the environmental impact. Recycling is an important source to satisfy the metal demand; as much of 30 % of the metal demand is covered by recycling in some markets. Another form of recycling is the practice of urban mining. A practice which includes recycling of society’s stocks of unused but not discarded metal, these unused amounts metal is part of a so called hibernating stock. An example of a very large stock is the infrasystems in the shape of power cables and pipes. The objective of this thesis is to quantify the metal stocks of copper, aluminium and iron in subterranean infrasystems in the city district of Södra Butängen in Norrköping. Also, a quantification for Norrköping as a whole is performed but on slightly different infrasystems. An economical valuation of these stocks is also performed. The Municipality of Norrköping has the ambition to transform this small industrial area, that Södra Butängen is today, into to a sustainability profiled residential and commercial area which opens up an opportunity to recycle the infrasystems when all buildings are removed and the ground is dug up. To fulfil the objective of the thesis, and quantify the metal stocks, so called static quantification was used. The infrasystems to be included in this study were chosen and the data describing these systems was collected from the respective owner of the systems. The gathered data consists of maps which were digitalized with GIS-software using ArcMap 10 where the stocks then were quantified. The results show that the infrasystems in Södra Butängen holds almost 600 tons of metal with an economical value of 4.67 million SEK. For the Norrköping quantification the results shows that the stock contains about 30,000 tons of metal. The economical value is a little over 70 million SEK. The hibernating stocks in Norrköping equals to 5,100 tons of metal and a value of 9.5 million SEK. There is a potential for urban mining in Södra Butängen that should be considered. However, there are some issues that also must be considered, like cost of extraction. There are large stocks of metal that not have been possible to identify in this thesis. This includes the power grid for Norrköping; a valuable stock due to its large copper content.
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ARAUJO, EDVAL G. de. "Efeito das adicoes de portadores de fosforo e da alumina na sinterizacao do aco rapido M2." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10766.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:95/03947-9
38
Sapkaitė, Ieva. "Metalų poveikis anaerobiniam dumblo apdorojimo procesui." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110621_170639-88279.
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Anaerobinis dumblo pūdymas - tai procesas, kurio metu dalis biomasėje esančių organinių junginių dėl įvairių rūšių mikroorganizmų veiklos yra suardomi. Vykstant šiam procesui, irstančios organinės dalelės verčiamos į biodujas – atsinaujinantįjį energijos šaltinį. Tačiau anaerobinis dumblo pūdymas gali sutrikti dėl įvairių inhibitorinių medžiagų. Norint reikiamą nuotekų išvalymo laipsnį užtikrinti pagal bendrąjį fosforą, naudojamas cheminis fosforo šalinimo būdas, kurio metu į nuotekas įterpiamos Al arba Fe metalų druskos.
Šio darbo tikslas ‒ nustatyti, kaip skirtingos aliuminio ir geležies koncentracijos veikia anaerobinio stabilizavimo procesą ir išgaunamų dujų kiekį.
Darbui atlikti buvo naudojamas standartinis anaerobinio pūdymo W8 (Armfield Ltd, UK) modelis. Tyrimu nustatyta, kad pūdant dumblą, į kurį buvo dozuota Fe druska, išsiskyrusių biodujų kiekis ml/d buvo artimas kontrolinio pūdytuvo reikšmėms, o pūdant dumblą, į kurį buvo dozuotos Fe ir Al druskos, biodujų ml/d išsiskyrė iki 30 % daugiau, nei palyginus su dumblu, į kurį druskos nebuvo dozuotos. Dozuojant metalų druskas ir esant padidėjusiai pūdytuvo apkrovai bepelenėmis sausosiomis medžiagomis, taip pat buvo nustatyta, kad sumažėja bepelenių sausųjų medžiagų suskaidymo efektyvumas iki 5—12 %. Nepaisant sumažėjusio bepelinių sausųjų medžiagų suskaidymo, biodujų m3/kgBSM suskaidytų padidėjo net iki 43 % pagal vidutines reikšmes.
Išanalizavus tyrimų rezultatus pateiktos išvados ir rekomendacijos. Darbą sudaro šios... [toliau žr. visą tekstą]Anaerobic sludge digestion is a process in which part of organic compounds existing in biomass are destroyed of various microorganisms. In this process volatile solids (VS) are converted into biogas – renewable energy source. Anaerobic digestion can be impaired in presence of inhibitors. Chemical phosphorus removal when Al and Fe metals salts are added to wastewater is used to reach the degree of waste water treatment by total phosphorus. Objective of this work was to investigate impact of different aluminium and iron doses on anaerobic digestion process and biogas produced. The work was carried out using standard anaerobic digestion model W8 (Armfied Ltd. UK). Research showed that biogas produced from Fe-dosed sludge was close to biogas production from un-dosed sludge and during digestion of Al-Fe-dosed sludge biogas ml/d production was 30% higher that from control. The efficiency of volatile solids destruction decreased 5-12% during dosing of metal salts. Biogas production from VS destructed was approx. 43% higher by average values when metal salts were dosed into sludge. The composition of biogas was not measured during research. Conclusions and recommendations are presented.
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PAOLA, JEAN C. C. de. "Efeito de tratamentos termicos e da adicao de cromo nas propriedades mecanicas de ligas Fe-24 atAl." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10664.
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Dissertacao(Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
40
Castan, Christophe. "Etude de la recristallisation au cours du laminage a chaud d’aciers a basse densite fer-aluminium." Thesis, Saint-Etienne, EMSE, 2011. http://www.theses.fr/2011EMSE0629/document.
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Les directives de l'Union Européenne conditionnent la R&D du secteur automobile concernant l'utilisation de matériaux plus légers ayant pour but de réduire la consommation de carburant et une diminution de l’émission de gaz d’échappement. L’objectif est de mettre au point des aciers allégés d’au moins 10% (ρmax ≈ 7g/cm3). Les alliages fer-aluminium possèdent des propriétés physiques et mécaniques prometteuses mais présentent des défauts de surface appelés roping, apparaissant après l’emboutissage à froid. Cette étude a consisté à mieux comprendre les conditions de recristallisation au cours du laminage à chaud afin de contrôler la microstructure et ainsi limiter ces défauts. Il est généralement admis, lors d’une déformation à chaud, que les alliages ferritiques, à haute énergie de défaut d’empilement, donnent lieu aux processus de recristallisation dynamique géométrique (RDG) et de recristallisation dynamique continue (RDC). Dans cette étude, l’existence d’une transition entre les mécanismes de RDC et de recristallisation dynamique discontinue (RDD) a été mise en évidence pour des températures comprises entre 900 et 1100°C et des vitesses de déformation comprises entre 0,1 et 50s 1. La recristallisation post dynamique a aussi été étudiée afin d’observer l’évolution de la microstructure lors de maintiens en température. Un modèle développé antérieurement pour la RDC de l’aluminium a ensuite été utilisé afin de simuler une passe de laminage. Bien que la comparaison des résultats expérimentaux et simulés fasse apparaître un certain nombre de différences, ce modèle permet de reproduire qualitativement les évolutions de la microstructureThe instructions of the European Union pilot the R&D in the automotive industry regarding the use of lightweight materials which aims at reducing fuel consumption and emission of exhaust gases.The objective is to develop steels of density reduced by at least 10% (ρmax ≈ 7g/cm3). Iron aluminum alloys display promising physical and mechanical properties but they often exhibit surface defects, referred to as roping, appearing after the deep drawing process. This study was carried out to better understand the conditions of recrystallization during hot rolling to control the microstructure and thereby limit these defects.During hot deformation, it is generally agreed that geometric dynamic recrystallization (GDRX) and continuous dynamic recrystallization (CDRX) operate in ferritic alloys with high stacking fault energy. In this study, the existence of a transition between CDRX and the mechanism of discontinuous dynamic recrystallization (DDRX) has been brought into evidence in the temperature range 900 1100°C and strain rate range 0.1-50s-1. Post-dynamic recrystallization was also studied to observe the evolution of microstructure during holding temperatures.A model formerly developed for the CDRX of aluminum was then used to simulate a rolling pass. Comparison of computed and experimental results shows some differences but this model can reproduce microstructural changes qualitatively
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Zacharopoulos, Marios. "Simulation numérique des fissures et du comportement ductile-fragile de l’aluminium et du fer." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066038/document.
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L'objectif principal de la présente dissertation est d'étudier le rôle des fissures pointues sur le comportement mécanique des cristaux sous charge à l'échelle atomique. La question d'intérêt est la façon dont un cristal pur, qui contient une seule fissure en équilibre mécanique, se déforme. Deux métaux ont été considérés: l'aluminium, qui est ductile à toute température, et le fer, transformé de ductile en fragile à une température décroissante inférieure à T=77K. Les forces de cohésion dans les deux métaux ont été modélisées via les potentiels phénoménologiques "n-body". A (010)[001] mode I nano-crack a été introduit dans le réseau cristallin parfait de chacun des métaux étudiés en utilisant des déplacements appropriés attribués par l'élasticité anisotrope. A T=0K, des configurations de fissures à l'équilibre ont été obtenues par minimisation d'énergie avec un type mixte de conditions aux limites. Les deux modèles ont révélé que les configurations de fissures restaient stables sous une gamme finie de contraintes appliquées en raison de l'effet de piégeage en treillis. La présente thèse propose une nouvelle approche pour interpréter le comportement mécanique intrinsèque des deux systèmes métalliques sous le chargement. En particulier, la réponse ductile ou fragile d'un système cristallin peut être déterminée en examinant si la barrière de piégeage en treillis d'une fissure préexistante est suffisante pour provoquer le glissement de dislocations statiques préexistantes. Les résultats des simulations ainsi que les données expérimentales démontrent que, selon le modèle proposé, l'aluminium et le fer sont ductiles et fragiles à T=0K, respectivementThe principal aim of the present dissertation is to investigate the role of sharp cracks on the mechanical behaviour of crystals under load at the atomic scale. The question of interest is how a pure crystal, which contains a single crack in mechanical equilibrium, deforms. Two metals were considered: aluminium, ductile at any temperature below its melting point, and iron, being transformed from ductile to brittle upon decreasing temperature below T=77K. Cohesive forces in both metals were modeled via phenomenological n-body potentials. A (010)[001] mode I nano-crack was introduced in the perfect crystalline lattice of each of the studied metals by using appropriate displacements ascribed by anisotropic elasticity. At T=0K, equilibrium crack configurations were obtained via energy minimization with a mixed type of boundary conditions. Both models revealed that the crack configurations remained stable under a finite range of applied stresses due to the lattice trapping effect. The present thesis proposes a novel approach to interpret the intrinsic mechanical behaviour of the two metallic systems under loading. In particular, the ductile or brittle response of a crystalline system can be determined by examining whether the lattice trapping barrier of a pre-existing crack is sufficient to cause the glide of pre-existing static dislocations on the available slip systems. Simulation results along with experimental data demonstrate that, according to the model proposed, aluminium and iron are ductile and brittle at T=0K, respectively
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PILLIS, MARINA F. "Estudo do comportamento de sulfetacao de ligas Fe20Cr." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10925.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
43
MALAVAZI, JEFFERSON. "Caracterização microestrutural dos compostos intermetálicos e seu efeito no comportamento mecânico nas ligas de Al-9%Si com adições de Fe e Mn." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10554.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
44
Zongo, Inoussa. "Étude expérimentale et théorique du procédé d'électrocoagulation : application au traitement de deux effluents textiles et d'un effluent simulé de tannerie." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL066N/document.
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L’électrocoagulation est une technique de traitement des eaux usées basée sur la dissolution d’anode sacrificielle de fer ou d’aluminium. Ces métaux se dissolvent sous formes de cations Fe2+ puis Fe3+ et Al3+ qui vont former des hydroxydes de métal qui entraînent par adsorption les impuretés de l’effluent en diminuant le potentiel Zêta de ces impuretés. Le réacteur électrochimique utilisé est constitué de deux électrodes métalliques (Fe ou Al) planes et parallèles qui laissent passer entre elles l’effluent à traiter. Des densités de courant de 50 à 200 A/m2 ont été appliquées pour traiter les trois effluents. L’un est un effluent directement issu d’une usine textile (effluent « usine »). Un second provient du flux d’entrée de la station d’épuration du site qui collecte les effluents de plusieurs usines (effluent « station »). Le troisième est un effluent artificiel de tannerie, créé en ajoutant 200 ppm de chrome VI à l’effluent « station ». Pour chaque expérience, la densité de courant et le temps de traitement vont déterminer la charge électrique et la concentration en métal dissous atteinte. L’influence de ces quatre paramètres sur l’élimination de la DCO, de l’absorbance, de la turbidité, du COT et du chrome hexavalent a été étudiée. L’évolution au cours du temps d’autres paramètres de l’EC tels que le pH, la tension, le rendement faradique et la dissolution métallique ont été étudiés afin de comprendre leur rôle dans le procédé. Le traitement a permis d’avoir un abattement maximal de DCO de 82% et 80% pour l’effluent « station » traité respectivement avec les électrodes de fer et d’aluminium ; 75 et 67% pour l’effluent « usine » traité respectivement avec les électrodes de fer et d’aluminium. L’abattement du chrome est de 100% avec les électrodes de fer mais tombe à 70% avec celles en aluminium. Des modèles d’élimination de la DCO et de l’absorbance ont été établis pour chaque matériau d’électrode utilisé. Le modèle d’élimination du chrome VI a été établi à partir du traitement avec les électrodes de fer. Une étude de la spéciation des espèces a permis de déterminer les pH optimaux de coagulation-floculation pour chaque métal impliqué (Al, Fe, Cr). La compétitivité entre l’abattement de la pollution organique et du Chrome a aussi été étudiée pour chaque type d’électrodeElectrocoagulation (EC) is a water treatment technology that relies on the electrochemical sacrificial anodes (in Fe or Al) dissolution. This metal dissolve themselves in Al3+ and Fe2+ cations that later oxidise to Fe3+ ions. These cations form metal hydroxides that adsorb the impurities of the effluent while decreasing the zeta potential. The electrochemical reactor used consists on two plane parallel metal electrodes with recirculation of the effluent to be treated between them. Current densities from 50 to 200 A/m2 were imposed to treat each effluent. Three effluents were used in this study. The first one is an effluent sampled at the outlet of a textile plant (« plant »). The second one is a mixture of several effluents coming from different plant and collected at the inlet of the wastewater treatment (« treatment plant »). The last one is a wastewater tannery plant simulated by addition of 200 ppm Chromium VI in the treatment plant effluent. For each experience the current density and the time of treatment rule the electrical charge and the concentration in dissolved metal reached. The influence of these four parameters on the elimination of COD, absorbance, turbidity, COT and hexavalent chromium content has been studied. Parameters e.g. potential, faradic yield, metal dissolution and pH have also been continuously monitored to better understand their role on EC process. The results show that DCO abatement reached 80 and 82% for treatment plant effluent, respectively with iron and aluminium electrodes; and 75 and 67% for plant effluent, respectively with iron and aluminium electrodes. The chromium treatment yields 100 % abatement with Fe electrodes whereas it is only 70% using Al electrodes. Models have been developed for COD and absorbance removal for the two electrode materials. Model for chromium (VI) treatment has been established considering all reactions occurring for iron EC. Metal speciation study allowed us to determine the optimal pH of coagulation –flocculation for each metal involved in the treatment (Al, Fe, Cr). Competition between organic pollution removal and chromium elimination has been also investigated for each electrode material
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COELHO, RODRIGO E. "Obtencao das ligas Al-Fe-X-Si (X = V ou Nb) por moagem de alta energia e extrusao a quente." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10870.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
46
Prinsloo, Andre. "The formation of chemical precipitates in the HAL process and its impact on electrostatic separation of zircon and rutile minerals." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/4577.
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Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2005.199 leaves single sided printed, preliminary pages i-vii and numbered pages 1-191. Includes bibliography, list of figures and tables. Digitized using a Hp Scanjet 8250 Scanner to pdf format (OCR).
ENGLISH ABSTRACT: This study provided scientific proof of the precipitation of iron and other metal species in the HAL circuit at the Mineral Separation Plant of Namakwa Sands. Iron and aluminium hydroxides were the most abundant precipitate complexes that formed in the HAL circuit. Sulphates formed bridges with the iron complexes. It was found that precipitation of iron in the HAL circuit was a function of the pH, ferric ion concentration and temperature of the process water. Experimental work provided abundant evidence that the precipitated iron hydroxide and other species adsorb to the surfaces of zircon and rutile mineral particles due to opposite zeta potentials of the mineral particles and iron hydroxide. These adsorbed species altered the electrostatic potential of the mineral surfaces, which reduced the electrostatic separation efficiency of these minerals. It was determined that an improvement of 7% could be expected if the precipitation and attachment of iron could be minimised. Based on the experimental results, conceptual processes were developed and iterative simulations were set up to determine the optimum solution that would maximise the removal of dissolved iron. This solution would ensure clean mineral surfaces free of any adsorbed precipitates. This process circuit was constructed in May to August 2004 at a total capital cost of R4.8m and removed 99.97% of the total dissolved iron prior to caustic addition. Prime zircon recoveries were increased by 3-7%.
AFRIKAANSE OPSOMMING: Hierdie studie het wetenskaplike bewyse gelewer dat yster en ander spesies neerslae vorm in die HAL proses van die Mineraal Skeidings Aanleg van Namakwa Sands. Yster- en aluminium hidroksiede was die vernaamste neerslag komplekse wat gevorm het in die HAL proses. Sulfaat spesies het verbindings gevorm met die yster komplekse. Die neerslag van yster was ‘n funksie van pH, ferric ioon konsentrasie en temperatuur van die proses water. Eksperimentele werk het genoegsame bewyse gelewer dat die yster hidroksied neerslag en ander spesies adsorbeer op die oppervlaktes van sirkoon en rutiel minerale weens teenoorgestelde zeta potensiale van die mineraal partikels en yster hidroksiede. Hierdie geadsorbeerde spesies het die elektrostatiese potentiaal van die mineraal oppervlaktes verander wat sodoende die elektrostatiese skeidingsvermoë van hierdie minerale verminder het. ‘n Verbetering van 7% in elektrostatiese skeiding van sirkoon en rutiel minerale kan verwag word indien die neerslag en adsorbsie van yster minimiseer word. Konseptuele prosesse, gebasseer op die eksperimentele resultate, is ontwikkel. Itteratiewe simulasies is opgestel om die optimum proses te bepaal wat sodoende die maksimum verwydering van die opgeloste yster sou verseker. Hierdie oplossing sou skoon mineraal oppervlaktes, vry van enige geadsorbeerde neerslae, verseker. Hierdie prosesaanleg was opgerig in Mei tot Augustus 2004 teen ‘n kapitaalkoste van R4.8m en dit het 99.97% van die totale opgeloste yster verwyder voordat natrium hidroksied bygevoeg is. Primêre sirkoon opbrengste het sodoende toegeneem met 3-7%.
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Opačitý, Radim. "Příčiny vzniku bodlin v litině s kuličkovým grafitem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229125.
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The aim of this thesis was to analyze the formation of defects in a given casting of ductile cast iron EN - GJS - 600-3 cast in sand molds bentonite, which is formed jolting with coining and then find a solution to remedy these defects. To resolve this issue, the influence of the composition of the sand mixture, the effect of metal flow in a cavity forms and the influence of deoxidation of metal in the presence of defects. Obtained results showed the importance of the influence Reoxidation metal cavity mold. Specifically, in this case succeeded in reducing the incidence of PINHOLES. Removal of PINHOLES to achieve deoxidation aluminum melt. This has reduced the production of nonconforming castings under 3% from the original 6.5%.
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SOUZA, KELLIE P. de. "A influência do ferro e do óxido de cério sobre a condutividade elétrica e a resistência à corrosão do alumínio anodizado." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11423.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
49
Aitsuradze, Malkhaz. "Entwicklung neuer Gießtechnologien für Leichtbaukomponenten." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2010. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-38738.
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Die Anforderungen, in vielen Bereichen des Maschinen- und Anlagenbaus immer mehr Leichtbaumaßnahmen zu realisieren, steigen ständig weiter an. Die Umsetzung von Leichtbaukonzepten wird durch den Einsatz neu entwickelter Werkstoffe und Werkstoffsubstitution realisiert. Es steht fest, dass die herkömmlichen Technologien eine weitere Steigerung der Leichtbaupotentiale nicht mehr gewährleisten können. In der vorliegenden Arbeit wurden neue innovative Fertigungstechnologien zur Herstellung von hohlen, MMC und damit massereduzierten Bauteilen entwickelt, die in der Kraftfahrzeugtechnik, Wärmetechnik und Medizin sowie im Maschinenbau Anwendung finden können. Die neuen Gießverfahren beinhalten Fertigungsmethoden auf der Basis des bekannten Niederdruckgießens durch gesteuerte Formfüllung und definierte Abkühlungsbedingungen.
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Eff, Michael N. "A Fundamental Investigation into Intermetallic Formation and Growth in the Aluminum-Iron System using Resistance-based Diffusion Couples." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563359657255421.
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