Search results for "oxydation"
showing 10 items of 32 documents
Additive manufacturing, new elaboration technique of metallic materials : impact of the microstructure on high temperature durability of AISI 316L st…
2021
Additive Manufacturing (AM) processes are able to elaborate, in a single step, metallic parts with very complex geometry, as close as possible to their final dimensions, based on 3D CAD model. Despite a very large number of studies on AM parameters, very few studies report on the high temperature behavior of the metallic materials produced by these processes. This thesis work evaluates the impact of the Selective Laser Melting (SLM) process on the high temperature durability of the austenitic stainless steel AISI 316L, commercial grade widely used in the industry. For this purpose, the reactivity of SLM samples was studied in different conditions (atmosphere, temperature, isothermal or cycl…
Study of the oxidation mechanisms of Plutonium
2022
Oxidation is a key point when applied to a material such as plutonium. It is essential to understand the oxidation mechanisms in order to predict and prevent catastrophic oxidation, thus managing the reprocessing cost.The originality of this work lies in the coupling of different experimental techniques : in-situ X-ray diffraction, Photo-electron spectroscopy (XPS), FIB-SEM, Raman spectrometry and X-ray absorption (EXAFS) with numerical techniques : CALPHAD and Reverse Monte Carlo, in order to determine the oxidation mechanisms of the studied alloy : -phase stabilised PuGa 1 at%.Study of oxidation of this alloy at different temperatures and oxygen partial pressures showed the oxidation kin…
Modélisation de phénomènes locaux : vers leur prise en compte dans la simulation de la cinétique d'oxydation d'un métal.
2006
The oxidation of metals is a complex process involving several mechanisms that take place at different length scale (macroscopic and microscopic). In this work, we try to integrate local phenomena (microscopic scale) in macroscopic models, especially to the modelling of the metal oxidation kinetics. The study is divided in two parts ; the first one based on non-equilibrium thermodynamics allows us to obtain the evolution laws of the system metal/oxyde, those were used to modelling oxidation kinetics. The second one is microscopic ; it consists in a study of the thermo-mechanical behaviour of various aluminium surfaces by molecular dynamic and the calculation of their surface energy density.…
Functionalised Imidazoporphyrins and their application in catalysis
2017
A broad series of functionalized imidazo[4,5-b]porphyrins was synthesized by the acid-catalyzed condensation of 2,3-dioxo-5,10,15,20-tetraarylchlorins with aromatic aldehydes. Both steric and electronic features of meso-aryl substituents influence on the product yield ranging from 18% to 90%.Single-crystal X-ray diffraction analysis of the structure of zinc(II) 5,10,15,20-tetramesityl-2-(4-pyridyl)-1H-imidazo[4,5-b]porphyrinate showed that this compound forms 1D coordination chains in the solid state.The post-synthetic modifications of imidazo[4,5-b]porphyrins were investigated by performing the Suzuki-Miyaura coupling reaction, preparing water-soluble imidazoporphyrins and linear/angular b…
ZnO(core)/TiO2(shell) composites : influence of TiO2 microstructure, N-doping and decoration with Au nanoparticles on photocatalytic and photoelectro…
2017
The aim of the thesis is to study the influence of microstructure of ZnO/TiO2 composites on their properties in photocatalytic degradation of organic pollutants, and in photoassisted water oxidation. To realize such study we chose the design based on ZnO nanorods supported on ITO (Indium Tin Oxide)-coated glass electrode. The ZnO nanorods were then covered with a layer of TiO2 under different conditions. The composition and microstructure of the obtained ZnO(core)/TiO2(shell) composites were modified in the aim to elucidate how these parameters influence their photocatalytic activity. The results of studies lead to elaboration of two most distinctive variants of sol-gel procedure that allow…
Peroxydation des lipides émulsionnés et transfert d'ions fer à l'interface huile / eau stabilisée par des protéines de lait : influence des résidus p…
2010
Iron incorporated into food systems induces oxidation and precipitation. The consequences are a reduced bioavailability and a modification of other food flavor. The iron chelates such as Fe-bisglycinate and Fe-EDTA represent a possibility to avoid side effects, since the iron is protected. The inertety of Fe bisglycinate and NaFe EDTA for lipid peroxidation has been verified in oil-in-water emulsion models stabilized by sodium caseinate or by β lactoglobulin through the following studies: i/ increase of primary and secondary products of oxidation, ii/ change of the properties of the oil/water interface (tension and interfacial rheology), iii/ the stability of the chelate iron (Fe-bisglycina…
Contribution to the molecular study of the oxidative stability of white wines of Burgundy
2019
In order to understand and control the aging of wines, particularly white wines, it is necessary to deepen our knowledge about the physico-chemical mechanisms of oxidation related to oxygenation processes. For this, it is important to have tools to quantify the antioxidant capacity of white wines, and to identify the compoiunds involved, in order to anticipate the aging ability of a wine.In this study, analyzes of the antioxidant capacity by DPPH and Electron Paramagnetic Resonance (EPR) were carried out on a large number of wines during aging and from several vintages, in parallel with metabolomic analyzes, mainly carried out by Liquid Chromatography Coupled to Mass Spectrometry (UPLC-Q-TO…
Etude comparative du catabolisme de l'acide ricinoléique chez les levures du genre Sporidiobolus : mise en évidence et caractérisation du système bét…
2002
*INRA Centre de Dijon (FRA) Diffusion du document : INRA Centre de Dijon (FRA) Diplôme : Dr. d'Université
Contribution to the study of interaction between residual stress and oxygen diffusion in a deformable and reactive solid
2011
The aim of this PhD work is to highlight the interactions between the mechanical stress and the chemical composition within diffusion of matter process for a reactive solid. The chronological evolution of our work goes from a parametric numerical study to an experimental study and reveals the role of mechanical stresses on the oxygen diffusion process.Different origins of mechanical stress were first numerically analysed from the point of view of their impacts on the process of oxygen diffusion into a metal (Zr) or a ceramic (UO2) subjected to an oxidizing environment. This approach allowed us: to identify a surface treatment (shot-peening) able to generate a residual specific stress field,…
Peroxydation in vivo et in vitro des acides gras polyinsaturés
2007
It is well admitted that polyunsaturated fatty acids are the most sensitive fatty acids to oxidative damage because of their high number of double bonds. This concept could not be confirmed by in vitro, animal, or human studies since unexpected or even contradictory results were obtained. The explanation of that is probably related to the methods evaluating lipid peroxidation whose relevance is not always established, but especially to movements of polyunsaturated fatty acids within lipoproteins that results in their protection. This short review aims to discuss the main results related to this topic.