Tesi sul tema "Nitruration de surface"
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Leblond, Edith. "Nitruration de l'aluminium par voies ioniques". Ecully, Ecole centrale de Lyon, 1998. http://www.theses.fr/1998ECDL0005.
Testo completoMarchand, Jean-Luc. "Contribution à la modélisation du procédé de nitruration ionique". Vandoeuvre-les-Nancy, INPL, 1988. http://www.theses.fr/1988NAN10180.
Testo completoGuillot, Benjamin. "Etude de procédés de préparation de surface avant nitruration - fiabilité du procédé". Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0068/document.
Testo completoThe gaseous nitriding of steel parts is a thermochemical process that generates a mechanical properties gradient at the surface by nitrogen diffusion. The treated parts indicate an important residual stress and hardness gradient, optimized for power transmission applications used in aeronautics and motor sports. The increase of nitrogen concentration is due to the catalytic decomposition of ammonia at the iron-based surface of parts. However, the process is extremely sensitive to the surface state of parts that includes geometrical, mechanical but also chemical properties. This state can inhibit the catalytic decomposition properties and the nitrogen diffusion. This deactivation can have different origins, such as the adsorption of a poisoning element or the fouling of the surface of the parts. The catalytic deactivation phenomenon is studied since decades. However, few publications are available in the case of its application in the specific case of the gaseous nitriding of steel. A better understanding of the nitriding inhibition would improve the reliability of this industrial process. In order to answer this demand, an experimental approach, based on industrial case and bibliographical study, is proposed. A pollution study obtained from machining oil residues, carbon deposit, or sulfur poisoning is proposed. Moreover, an experimental approach, aiming to determine the impact of initial mechanical properties on the nitriding process is proposed. Thermogravimetric analyses coupled to observations and mechanical properties analyses enable to develop the knowledge of the nitrided surfaces deactivation processes. After this study, the surface activation capacity of three in-situ processes, namely oxidation, urea and ammonium chloride, over the previously studied contaminations is determined
Petat, Bertrand. "Contribution à l'étude de la nitruration du fer par un plasma continu-pulsé". Nancy 1, 1990. http://www.theses.fr/1990NAN10541.
Testo completoPerito, Cardoso Rodrigo Belmonte Thierry Henrion Gérard. "Plasmas micro-ondes en cavité résonnante à la pression atmosphérique étude des plasmas d'hélium et applications au traitement des matériaux /". S. l. : INPL, 2007. http://www.scd.inpl-nancy.fr/theses/2007_PERITO_CARDOSO_R.pdf.
Testo completoMalvos, Hugues. "Diagnostic de décharges et post-décharges établies a diverses fréquences (de 13,56 mhz a 2450 mhz) dans des mélanges ar-n#2-h#2-ch#4 en écoulement : contribution à la réalisation et à la modélisation d'un réacteur de nitruration fonctionnant en post-décharge micro-onde". Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL041N.
Testo completoSamih, Youssef. "Thermomechanical surface treatments of austenitic stainless steels and their effects on subsequent nitriding during “Duplex” treatments". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0100/document.
Testo completoOptimizing the surface microstructure and properties is very important to obtain high performance behaviour. Applying appropriate mechanical and thermochemical treatments has been the prime objective of metallurgists. More recently, and particularly for the stainless steels, the Plasma Nitriding was found to be an efficient technique for enhancing the hardness and wear resistance. However, as the nitriding temperature is about 500 °C, the formation of nitrides on the surface leads to a decrease of the corrosion resistance of these alloys. Recent works have shown that using a mechanical pre-treatment allows to decrease the treatment temperature and duration, and also to enhance the nitrogen diffusion within the stainless steels surfaces. In the present work, performances of different Duplex treatments (mechanical + thermochemical) are studied. The Surface Mechanical Attrition Treatment (SMAT), cold rolling and the High Current Pulsed Electron Beam (HCPEB) are used as surface activators prior to plasma nitriding of stainless steels. Before studying the effect of surface activation on the nitrogen diffusion, the effect of the different SMAT parameters (balls size, balls nature, treatment duration … etc.) on the microstructure is analysed. A new technique based on the notion of Geometrically Necessary Dislocations (GND) is used to depict the thickness of the different SMAT-induced layers and compare the effect of the processing parameters. Then, comparative analysis of the results obtained after nitriding of mechanically deformed samples leads to quantify the effect of the different Duplex treatments. X-Ray Diffraction, Secondary Electron Microscopy associated with Electron BackScattered Diffraction (EBSD), hardness measurement and chemical composition analysis by Glow Discharge Optical Emission Spectroscopy (GD-OES) showed the importance of the surface microstructure and deformation state on the nitrogen diffusion
Bockel-Macal, Savine. "Étude d'un procède de nitruration assistée par une post-décharge micro-ondes Ar-N₂-H₂ en écoulement : diagnostics de la phase gazeuse et modélisation du réacteur". Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL018N.
Testo completoIacob, Constantin. "Transfert thermique et transfert de masse en lit fluidise. Application à la nitruration d'aciers". Rouen, 1996. http://www.theses.fr/1996ROUES020.
Testo completoOseguera-Peña, Joaquin Esteban. "Contribution à l'étude de la nitruration des aciers entre 3 et 500 hPa dans l'azote et différents mélanges gazeux N2-H2 ou Ar-N2 en conditions de post-décharge micro-onde en écoulement". Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1990INPL018N.
Testo completoBédouin, Yvan. "Nitruration d'un alliage titane-niobium à bas module pour l'implantologie orale". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1B032.
Testo completoThis work was performed in collaboration with the Metallurgical Chemistry team of the Institute of Chemical Sciences of Rennes and the Biomaterials Laboratory of the Faculty of Dentistry of Université de Rennes1. The low modulus Ti-27Nb (at. %) alloy with non-toxic elements was nitrided for the first time in this study for dental implant applications. The alloy was firstly synthetized by cold crucible levitation melting technique. A high temperature gas nitriding treatment was then carried out in order to improve the wear and corrosion resistance. The structural analysis was performed by X-ray diffraction and the microstructure was observed by optical microscopy and by scanning electron microscopy. The chemical analysis was performed by Energy Dispersion Spectrometry. Superficial mechanical properties were then studied by nano-indentation and ball-on-disc tribological tests. Conventional and tensile tests were realized. The biocompatibility was evaluated by in vitro tests performed on human osteoblasts, fibroblastic cells and epithelial cells. Cell proliferation and differentiation were studied as well as cell morphology. All of the observed properties make the nitrided Ti-27Nb alloy particularly suitable for enhanced longevity of dental implants
Yang, Xiaofang. "Development of hybrid surface mechanical attrition treatment : formation of carbon and nitride nanomaterials". Troyes, 2009. http://www.theses.fr/2009TROY0009.
Testo completoSince the development of the new technique SMAT (Surface Mechanical Attrition Treatment), great success has been achieved. The mechanical properties and the diffusion properties of materials treated by SMAT are greatly improved. Carbon nanomaterials such as carbon nanofibers (CNFs) and carbon nanotubes (CNTs) have attracted special attention due to their unique properties and potential application. Since the diffusion properties of materials have been improved after the SMAT process, a SMAT process followed by a CVD process, i. E. Hybrid SMAT, is tailored for synthesizing carbon nanomaterials in-situ on the surface of bulk metallic materials. 316L stainless steel, pure Co, pure Ni and pure Ti plate were subjected to hybrid SMAT process to synthesize carbon nanomaterials. The effects of main parameters are discussed. The products were investigated by SEM, TEM, XRD and RAMAN characterizations. Growth mechanism was proposed. The second part of work concerns the development of SMAT machine and the formation of nitride nanomaterials on bulk metallic materials. A new SMAT system that can provide various treating conditions was developed to form a thicker nanostructured surface layer. 316 stainless steel samples were subjected to the new system, treating under traction and under thermal stress respectively. The treated samples were investigated by optical micros-copy, XRD and nanoindentation. Treated samples were submitted to the nitriding process to form nitride nanomaterials. The nitride samples were investigated by optical microscopy and microhardness tester
Marot, Laurent. "Développement d'un nouveau système d'implantation ionique en immersion plasma et analyses des processus de nitruration". Phd thesis, Université de Poitiers, 2001. http://tel.archives-ouvertes.fr/tel-00003632.
Testo completoDuez, Nicolas. "Contribution à l'étude de la nitruration de l'aluminium et du silicium par plasma d'azote en résonance cyclotronique électronique répartie". Lille 1, 2000. http://www.theses.fr/2000LIL10188.
Testo completoAndrieux, Aurore. "Traitements thermochimiques basse température assistés par plasmas d’un acier inoxydable austénitique pour la micro-structuration de surface d’un contact lubrifié". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0095/document.
Testo completoSurface patterning can improve friction properties of a lubricated contact by the generation of hydrodynamic pressure. The objective of the ANR project MicroGaMe was to pattern the surface of a mechanical seal in austenitic stainless steel. We developed a process based on the use of low-temperature plasma-assisted thermochemical treatments (nitriding and carburizing). The study of the treated layers leads to a better understanding of its nature and of the formation mechanisms and also reveals the presence of nanoprecipitates. During the treatments, a deformation occurs in a direction perpendicular to the surface (called “swelling”) as a consequence of high internal stresses, which can be used as an original patterning driving force. To obtain a “positive” pattern, we treated samples through laser-cut steel plates. A “negative” motif (cavitie) requires the use of a discontinuous mask so we tested different deposition techniques. As the specific shape and dimensions needed for the application to a mechanical seal cannot be obtained with this approach, we also develop an ion etching process, which has been successfully applied to real size piece
Chemkhi, Mahdi. "Nanocristallisation superficielle couplée à la nitruration plasma pour augmenter les propriétés de fatigue et d’usure d’alliages métalliques". Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0038/document.
Testo completoCoupled mechanical and thermochemical surface treatments have been the subject of much research effort in recent years. The goal of such a coupling is to improve diffusion kinetics leading to increased penetration depths, and/or to decrease the treatment temperature for mechanically pretreated materials. In this work, SMAT (Surface Mechanical Attrittion Treatment), used to refine the grain size by severe plastic deformation, is combined with plasma nitriding of a 316L medical-grade stainless steel. This duplex process significantly improves nitrogen diffusion. An intermediate treatment between SMAT and plasma nitriding is also proposed and its significant effect on the nitrogen diffusion is demonstrated. Comparisons between nitrided-only samples and duplex-treated samples have shown up to 60% increase of the nitrided layer thickness. In order to better understand the link between the generated microstructures and the mechanical fatigue and tribological responses, the samples have been characterised by many different techniques. Also, a multiscale numerical model of the diffusion process is proposed in order to simulate the nitrogen concentration profiles after duplex treatment. The simulated and experimental profiles correspond rather well
Abrasonis, Gintautas. "Nitruration par faisceau d'ions des aciers austénitiques inoxydables : étude du transport atomique d'azote, des effets de flux et des effets structuraux". Poitiers, 2003. http://www.theses.fr/2003POIT2291.
Testo completoDetourbe, Sylvie. "Contribution à l'étude des traitements mixtes de nitruration et d'oxydation assistés par plasma en vue d'améliorer la résistance à la corrosion atmosphèrique des aciers". Vandoeuvre-les-Nancy, INPL, 1989. http://www.theses.fr/1989NAN10399.
Testo completoDe, Pauw Virginie. "Mécanismes de nitruration et d'oxydation du composé intermétallique Sm2 (Fe, Co)1#7 pour aimants permanents". Rouen, 1996. http://www.theses.fr/1996ROUES053.
Testo completoGallitelli, Donato. "Traitements de surface mécaniques : modélisation et caractérisations expérimentales". Thesis, Troyes, 2018. http://www.theses.fr/2018TROY0013.
Testo completoMechanical surface treatments are widely used in manufacturing industries in order to improve mechanical properties of materials. Among them, shot peening is certainly the most known, even if ultrasonic shot peening and laser shock peening are becoming more and more common. This work consists in a large study of shot peening, divided in three parts.The first one is focused on the conception of a semi analytical model for residual stress prediction after conventional shot peening or ultrasonic shot peening. An approach able to chain the whole shot peening process, starting from process parameters to residual stress field in a structure is proposed. Several numerical simulations of shot-body impacts are carried out in order to determine the parameters of the model.In the second part of this work, a characterization of the ultrasonic shot peening process is performed thanks to many experimental measurements and shot dynamic simulations.The last part of this PhD work corresponds to an experimental analysis focused on the combination of ultrasonic shot peeing with gas nitriding on a martensitic steel. A comparison between ultrasonic shot peening, conventional shot peeing and laser shock peening effects is finally proposed
Stinville, Jean-Charles. "Evolution des microstructures et textures locales par nitruration plasma de l'acier 316L : répercussion sur sa durabilité en fatigue". Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2010. http://tel.archives-ouvertes.fr/tel-00491846.
Testo completoFouquet, Valérie. "Etude des mécanismes d'implantation et diffusion lors de la nitruration du titane et de Ti-6Al-4V par implantation ionique en immersion plasma". Poitiers, 2004. http://www.theses.fr/2004POIT2271.
Testo completoThe aim of this work is to study the implantation and diffusion mechanisms occuring during nitridation of titanium and of Ti-6Al-4V by plasma based ion implantation. Chemical and microstructural studies allow the determination of the characteristics of the phases formed depending on the treatment parameters. The implantation is the main formation mechanism of nitrides at low temperature whereas the nitridation is mainly controlled by the thermally activated diffusion at high temperature. By means of a numerical resolution of the equation of diffusion taking into account the experimental observations, implantation-induced defects have been shown to enhance the diffusion coefficient in the nitride layer. The in-depth nitridation of titanium is however favoured by the continuously implanted nitrogen in the nitride layer which acts as an in-depth source. On the contrary, in a thermal-activated treatment, the nitride forms a diffusion barrier which limits the later incorporation of nitrogen
Thirion, Valérie. "Croissance et nitruration à basse pression d'oxydes minces de silicium : caractérisations physiques et électriques pour l'application aux dispositifs CMOS". Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10052.
Testo completoRenevier, Nathalie. "Étude d'un réacteur de nitruration à basse pression assistée par un plasma de décharge d'arc : application au traitement de surface des aciers, de l'aluminium et du titane". Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL001N.
Testo completoGuo, Yuanyuan. "Etude des interactions entre l'azote et le carbone lors de traitements séquencés de nitruration, de carburation et de nitrocarburation à basse température d'aciers inoxydables austénitiques : application à la texturation de surface". Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL047N/document.
Testo completoDifferent aspects of thermochemical treatments (nitriding, carburizing and nitrocarburizing) of austenitic stainless steel AISI 316 L conducted at low temperature were discussed. In the first chapter, a state of the art of these thermochemical treatments, as well as techniques used to achieve them have been presented. The nitriding and carburizing treatments, performed in a plasma reactor assisted by microwave in the Matrix Distributed Electron Cyclotron Resonance configuration, were studied in chapter 3. Analysis of the treated layers was performed by different experimental techniques: optical microscopy, profilometry, X-ray diffraction, Secondary Neutral Mass Spectroscopy, Secondary Ion Mass Spectrometry and glow discharge spectroscopy. In the fourth chapter, the nitrocarburizing treatment was studied and compared to sequenced carburization / nitriding and nitriding / carburizing treatments. A strong correlation was made between the average concentration of interstitial elements and the average compressive residual stress in the treated layers. The final chapter deals with the surface texturation or patterning to the nanometer or micrometer scale. To achieve this patterning, the deformation properties of the expanded austenite, formed during a nitriding treatment at low temperature, are used to construct a two dimensional array of dots, using grids or metallic tissues playing the role of masks to transfer a pattern on a piece of austenitic stainless steel
Rabbe, Louis-Marie. "Comportement physico-chimique d'un contact métal/polymère soumis à un frottement sous petits débattements en milieu chlorure : influence des traitements de surface par implantation et nitruration ioniques". Grenoble INPG, 1993. http://www.theses.fr/1993INPG4207.
Testo completoLabidi, Chafik. "Amélioration de la durée de service d'outils d'usinage du bois par traitements de surface et préparation de l'arête de coupe". Phd thesis, Paris, ENSAM, 2006. http://pastel.archives-ouvertes.fr/pastel-00002491.
Testo completoSaker, Abdelhamid. "Étude des produits de pulvérisation cathodique magnétron et de nitruration a basse température des aciers inoxydables austénitiques dans des plasmas réactifs contenant de l'azote". Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL017N.
Testo completoCollin, Monique. "Élaboration et caractérisation de revêtements de nitrure et carbure de titane par laser continu sur l'alliage de titane TA6V". Paris 11, 1988. http://www.theses.fr/1988PA112384.
Testo completoDingremont, Norbert. "Analyse de la compatibilité des traitements de nitruration par voie ionique avec les dépôts par plaquage ionique : application à l'acier de construction 35NCD16 et à l'acier d'outillage pour travail à chaud Z38CDV5". Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL110N.
Testo completoVautherin, Béatrice. "Elaboration par projection plasma réactive sous très basse pression de dépôts de matériaux dans le système Aluminium-Titane-Azote". Thesis, Belfort-Montbéliard, 2014. http://www.theses.fr/2014BELF0239/document.
Testo completoThe Very Low Pressure Plasma Spraying (VLPPS) is an emerging deposition process tomanufacture metallic and ceramic coatings, under a very low surrounding pressure, typically about onehundred Pascal, thanks to a thermal plasma jet. Such a pressure range allows principallymanufacturing coatings by condensation of vapors resulting from the vaporization, partial or total, ofsolid precursors, in most of the cases. This is the main difference of this process compared to moreconventional thermal spray processes, which form coatings by spreading, solidification and stacking ofparticles melted in a high energy jet. Depending upon the spray operating conditions, coatingsmanufactured by VLPPS exhibit different types of microstructures, from columnar to lamellar, fromdense to porous. The coating building dual mode, made of condensed vapors and molten particles isalso possible.The aim of this work is to explore in a reactive mode the VLPPS potential to manufacturecoatings made of materials exhibiting a non-congruent melting behavior. Here, for a demonstrationpurpose, Aluminum and Titanium were considered as the metallic precursors and Nitrogen as thereactive element. Therefore, materials which could result would be Aluminum and Titanium nitrides.Some possible applications could result directly from this study: the manufacturing on large surfacesof Aluminum and Titanium nitride layers, exhibiting good oxidation resistance and tribologicalproperties, especially a high wear resistance.In this study, metallic coatings of Aluminum, Titanium and Aluminum-Titanium and Al-AlN,Ti-TiN and TiAl-TiAlN coatings were manufactured by reactive VLPPS. Nitrided composite coatingsexhibit, for example, higher average hardness than metallic coatings, Those coatings embed up to 30at.% of Nitrogen and TixN, AlN and TixAlN compounds were clearly identified
Lacaille, Victor. "Traitements thermochimiques de surfaces nanostructurées. Modélisation numérique et expérimentation". Ecole nationale d'ingénieurs (Saint-Etienne), 2015. http://www.theses.fr/2015ENISE034.
Testo completoSurface mechanical attrition is a way to improve the hardness of mechanical parts. It affects directly the microstructure of the treated part. In addition to their excellent hardness, wear resistance and fatigue resistance properties, nanostructured surfaces boost the diffusion of chemical elements and improve in this way the efficiency of thermochemical treatments which are also hardening methods by chemical processes. Although the reasons of this efficiency improving are known, the quantification of its effects is not still much understood. This work aims by numerical and experimental studies to give the basics for the creation of prediction tools of these effects. First, a finite elements analysis on representative volume elements leads to an analytical model and to an abacus for the prediction of the diffusion coefficient of a chemical element in a material with a given microstructure. The experimental part points out on a model material (Iron) that the effects of surface nanostructuring on nitriding stand mainly in the diffusion kinetics. It also gives data required for the explanation of experimentally observed phenomenon that the following chapter concerns. The last chapter of this work aims to elaborate the beginnings of an industrial tool which predicts the gain obtained by surface nanostructuring on the thermochemical treatment of a given material
Monier, Guillaume. "Nanostructuration de surfaces de GaAs : oxydation et nitruration". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00673419.
Testo completoRocancourt, Norman. "Etude de solutions innovantes de dépôts de superalliages et traitements de surface pour augmenter la résistance à l'usure et le comportement des moules métalliques de verrerie". Electronic Thesis or Diss., Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0014.
Testo completoGlass moulds have to withstand very high temperatures which can far exceed 650 °C during the glass forming process. They are exposed to very tough conditions such as abrasive wear and physico-chemical reactions, accentuated by thermal shocks due to high speed contact with hot glass melt. The aim of this work is to find innovative solutions for superalloy coating or surface treatments in order to increase the service life of glass tools. Three innovation projects are presented in this report. The first one is dedicated to PTA (Plasma Transferred Arc) welded coating of composite Co/NiB powder on copper alloy moulds. The second one is about technical feasibility of a multilayer PVD (Physical Vapor Deposition) coating with properties congruent to glass production in term of hardness and thermal stability, on AISI 431 plunger stainless steel. Last but not least, the third innovative project is about nitriding by ion implantation with multicharged nitrogen ions on AISI 431 stainless steel. We notice after ion implantation a significant hardness increase (+ 240 %). A multi-experimental and multi-scale approach was carried out in order to study the implanted material microstructure and its evolution after annealing at 650 °C during 1h to predict the material behavior during production and correlate it to hardness properties
Perito, Cardoso Rodrigo. "Plasmas micro-ondes en cavité résonnante à la pression atmosphérique : étude des plasmas d'hélium et applications au traitement des matériaux". Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL103N/document.
Testo completoThe present work deals with the study of helium microwave plasmas at atmospheric pressure generated in a resonant cavity and their applications in surface treatment. First of all, a state of art of microwave atmospheric pressure plasmas and their applications is presented. Next, a collisional-radiative model for pure helium discharge and post-discharge is described. The results of the model are compared to experimental data obtained at 2500 K and a coherent set of cross-sections and rate constants is obtained for these conditions. Emission and absorption spectroscopy diagnostics are employed to characterize the helium plasma. The gas temperature is determined by the rotational synthetic spectra method. The evolution of the gas temperature, as a function of the input power, the concentration and the nature of impurities in helium, is measured. It turns out that the plasma volume plays a significant role on the gas temperature. The He(23S) concentration is determined by laser absorption in pulsed and continuous mode. In continuous mode, the metastable concentration is divided by 3 with 360 ppm of impurity, regardless of the nature of the impurity. Nevertheless, during the post-discharge, in pulsed mode, the nature of the impurity plays an important role. These measurements support the idea that He+ and not He2+ is the main ion. Concerning the applications, only post-discharges are utilized. We demonstrate that deposition of SiOx using hexamethyldisiloxane as precursor can be efficient. We show that titanium nitriding at high temperature is possible
Thiriet, Tony. "Traitement mécaniques et thermochimiques couplés sur acier inoxydable et alliage base nickel austénitiques". Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL064N/document.
Testo completoRecent scientific work has opened new fields of application to mechanical treatments such as shot blasting or peening. Indeed, it has been shown that this treatment, performed before a nitriding treatment on the surface of ferrous alloy, lowers processing temperatures and significantly increases the diffusion kinetics. We undertook to test this combination of mechanical and thermochemical treatments on stainless steels and nickel-based alloys. The mechanical treatments were done by Surface Mechanical Attrition Treatment (SMAT). This method is implemented in a box where metal or ceramic balls were introduced and set in motion by an ultrasound system in order to impact the surface of the pieces. The treated samples were then nitrided at low temperature by using a remote plasma. The comparison of the results obtained after nitriding treatments on mechanically treated samples and those not mechanically treated allows quantifying the effects of the combined treatments. Analyses by X-ray diffraction, microhardness measurement, observations by optical and scanning and transmission electron microscopy, texture analysis by EBSD (Electron Diffraction BackScatered) and measurement of nitrogen concentration profiles by SIMS (Secondary Ion Mass Spectrometry) show the importance of the nature of the deformed layer
Bouanis, Fatima Zahra. "Amélioration des propriétés anticorrosion d’un acier au carbone par nitruration par plasma froid radiofréquence". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10183.
Testo completoThe aim of this work concerns the study of the improvement of the corrosion resistance in acidic medium (1M HCl) and mechanical properties of carbon steel (XC38) using a radiofrequency cold plasma nitriding process. The originality of this work consists in nitriding substrates using nitrogen cold plasma, where the process temperature is roughly ambient temperature and without heating the substrate. The nitriding was carried using nitrogen and nitrogen/ hydrogen plasma gas mixtures. The hydrogen role in the plasma consists not only in reducing the iron oxide layer on the substrate, but also accelerates the nitrogen diffusion in the substrate. Surface characterizations performed by means of the Electron Probe Microanalysis (EPMA) and X-ray Photoelectron spectroscopy (XPS) indicate that the treatment plasma induces the formation of a layer where the nitrided thickness is higher than ten microns for long treatment times (8h). The mechanical properties were studied by Vickers microhardness. The surface microhardness of the nitrided steel increases as the plasma processing time increases to reach a maximum of 1057Hv0.005 for the nitrided sample that was treated during 8h, when compared to sample untreated (247Hv0.005). The improvement of the corrosion resistance properties were investigated by gravimetric and electrochemical techniques such as potentiodynamic polarisation curves and electrochemical impedance spectroscopy (EIS) in 1M HCl medium. For the optimal conditions of treatment, the inhibition efficiency obtained is more than 95 % for 8h of treatment and remains constant for immersion times higher than 72h in aggressive medium (HCl 1M)
Rocancourt, Norman. "Etude de solutions innovantes de dépôts de superalliages et traitements de surface pour augmenter la résistance à l'usure et le comportement des moules métalliques de verrerie". Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0014.
Testo completoGlass moulds have to withstand very high temperatures which can far exceed 650 °C during the glass forming process. They are exposed to very tough conditions such as abrasive wear and physico-chemical reactions, accentuated by thermal shocks due to high speed contact with hot glass melt. The aim of this work is to find innovative solutions for superalloy coating or surface treatments in order to increase the service life of glass tools. Three innovation projects are presented in this report. The first one is dedicated to PTA (Plasma Transferred Arc) welded coating of composite Co/NiB powder on copper alloy moulds. The second one is about technical feasibility of a multilayer PVD (Physical Vapor Deposition) coating with properties congruent to glass production in term of hardness and thermal stability, on AISI 431 plunger stainless steel. Last but not least, the third innovative project is about nitriding by ion implantation with multicharged nitrogen ions on AISI 431 stainless steel. We notice after ion implantation a significant hardness increase (+ 240 %). A multi-experimental and multi-scale approach was carried out in order to study the implanted material microstructure and its evolution after annealing at 650 °C during 1h to predict the material behavior during production and correlate it to hardness properties
Jelliti, Sami. "Étude des performances mécaniques surfaciques d'alliages métalliques par traitement duplex nanostructuration-nitruration ionique pour applications biomédicales [prothèses orthopédiques]". Compiègne, 2012. http://www.theses.fr/2012COMP2014.
Testo completoIn terms of biomaterials protection against corrosion and wear, several approaches are possible: modify the chemical environment and operating conditions, change the material or also modify its properties. The first two options require a complete revision of a conceptual set and can therefore lead to new difficulties and additional costs. The third approach, which consists on modifying the biomaterial’s surface properties, is the simplest to implement as it aims to adapt the biomaterial to the different constraints of its environment and therefore requires a smaller investment. In order to improve the mechanical surface properties (hardness, roughness…), chemical proprieties (corrosion resistance) and tribological proprieties (wear resistance) of biomaterials, it was decided to set up a nanostructuring treatment SMAT (Surface Mechanical Attrition Treatment). Microscopic observations revealed the presence of a nanostructured layer on the surface of the titanium alloy Ti6Al4V and 316L stainless steel. The electrochemical experimental results showed an improvement in the corrosion resistance of used biomaterials in particular for the titanium alloy. Thus, electrochemical properties have been demonstrated through corrosion tests (monitoring free potential, polarization curves, impedance diagrams. . . ) associated with microscopic observations (SEM) and XPS analyses. Through this technique, we could appreciate the quality and extent of the layer on the surface which is a fundamental parameter for determining the corrosion behavior of biomaterials. In the second part, a duplex SMAT-nitriding treatment was applied on Ti6Al4V. More significant improvement of corrosion properties was observed on the SMATed and nitridtreated titanium alloy. In the last section, we addressed the surface mechanical properties (hardness, roughness) of biomaterials after SMAT. The roughness profiles have increased and hardness values showed a maximum near the outermost treated surface. Fretting tests were performed on different samples. SMAT treatment slightly reduces the coefficient of friction and decreases the mass loss
Aubel, Dominique. "Apport des techniques de photoémission à la connaissance des hétérostructures Ge/Si(001), Si/Ge(001), Si1-xGex/Si(001) et Si1-xGex/Ge(001)". Mulhouse, 1995. http://www.theses.fr/1995MULH0412.
Testo completoNORMAND-CHAVE, CAROLE. "Etude et modelisation de la post-decharge d'une decharge micro-onde d'azote ou d'argon-azote en flux : application a l'etude d'un reacteur de nitruration de surfaces metalliques fonctionnant en post-decharge". Paris 11, 1991. http://www.theses.fr/1991PA112210.
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