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Sciences et génie des matériaux

Nombre total de résultats : 47
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Microstructure and mechanical behavior in dissimilar 13Cr/2205stainless steel welded pipes

K. Bettahar, M. BOUABDALLAH, R. Badji, M. Gaceb, C. KAHLOUN, B. BACROIX (2015)

Thiswork aims to investigate the microstructure and themechanical behavior of dissimilar 13Cr Supermartensitic/2205 Duplex stainless steelwelded pipes. A wide variety ofmicrostructures resulting fromboth solidification andsolid state transformation is induced by the fusion welding process across the weld joint. The tensile tests showthat the deformation process of the dissimilarweld joint ismainly controlled by the two basematerials: the duplexsteel at the beginning of the deformation and the supermartensitic one at its end. This is confirmed by the microtensiletests showing the overmatching effect of the weld metal. The fatigue tests conducted on dissimilar weldedspecimens led us to conclude that the weld metal is considered as a weak link of the weld joint in the high cyclefatigue regime. This is supported by its lower fatigue limit compared to the two basematerials that exhibit a similarfatigue behavior.Voir les détails

Mots clés : Dissimilar welding, microstructure, Tensile testing, High cycle fatigue

Study of structural and thermal properties of SiO2 and Al2O3 in the Diatomite

K.Boubendira, K.LABIOD, S.BENAYACHE, F.AOUADJA, H.Meradi (2016)

Diatomite is a light colored rock formed entirely or substantially of "backbones" of diatoms. These unicellular algae are surrounded by a "shell" in silica, frustule, the accumulation of the substance can lead to the formation of a rock.In this work we determine the structural and thermal properties of SiO2 and Al2O3 in the diatomite using the plane wave method and linearized augmented (LAPW) in the functional theory of density (DFT).The potential for exchange and correlation is calculated by the generalized gradient approximation (GGA).Regarding thermal properties, we calculated the free enthalpy G, S entropy, specific heat C, thermal conductivity λ ..... etc of SiO2 and Al2O3 component. The temperatures used in this work are 1400, 1450 and 1500 respectively;The results are in good agreement with some experimental data.Voir les détails

Mots clés : DFT1, diatomite, thermal proprieties

Corrosion of Multi-Material in Marine Environment. .

Djilali Allou (2016)

The aim of this study is the characterization of multi-material developed by Hardfacing using the Manual Arc welding (SMAW) process. To highlight the effect of the thermal cycle on the interfaces cohesion, particularly on the steel substrate.We focused on the electrochemical behavior of the hardfacing in marine environment and evaluated the influence of heat treatment on the different parts of the Hardfacing. Microstructural characterization was assessed using the optical microscope (MO).Voir les détails

Mots clés : 25CD4Steel, Hardfacing, electrochemical characterization, corrosion

Quality and performance of sacrificial anodes used in cathodic protection

S.Bouyegh, M.Ouadah, F.Brihmat, D. Allou. (2016)

Abstract— Sacrificial anode cathodic protection is one of the most techniques used to protect metallic structures from corrosion in seawater. In this paper, the morphology of corrosion products on the surface of the Zinc anodes in seawater was studies. To achieve this objective, zinc anodes samples were immersed in natural seawater, for different times at room temperature. The samples before and after immersion were cleaned according to the standard method. The morphology of corrosion products was examined by optical and scanning electron microscopy (MEB) .Energy dispersive X-ray spectroscopy (EDS) was used to analyze the elements distributions. The results show that the corrosion product can take many forms depending on the structure of the metal and the corrosive environment.Voir les détails

Mots clés : sacrificial anode, immersion, corrosion products, cathodic protection.

Simulation of the propagation of cracking by finite element code calculation of a supermartensitic stainless steel pipe

K.SLIMANI1, 2, M.HASSANI 2, S. TLILI1, 3, C.E. RAMOUL1, T. HAZEM1 (2016)

The biggest concern of industrial manufacturers is the sustainability of their equipment and facilities. In the oil sector, for example, cylindrical pipe for the energy transportation to suffer corrosion damage or corrosion stress cracking is a complex problem since it requires to follow the geometry of the crack over time. Many numerical methods are applied to the propagation of fatigue cracks that require conditions to correct limitations in loading term to get results close to reality.The method of Finite Elements is a way to simulate crack propagation. However, it presents two major difficulties, the first is the use of a very fine mesh around the crack tip and the second difficulty is the explicit representation of the crack that the problem of cracking path during the simulation of propagation. Indeed, let the mesh is constructed with a priori knowledge of the route or it is changed every time the crack advance.In this context, we studied law cracking of internal pressure pipe of super martensitic stainless steel 13% Cr and 5% Ni 2% Mo by a simulation using a finite element code "ANSYS " with a calculation of the stress intensity factor and prediction of the lifetime.Voir les détails

Mots clés : simulation, Finite Elements, Crack, Pipe, Super Martensitic Stainless Steel.


Belgacem BEZZINA  (2012)
Mémoire de magister

This work aims at finding an optimal composition of a water repellent admixture for waterproofing concrete and mortar. The composition optimization is performed by implementing an experimental design type D‐optimal. The influence of four main components (A :Oil, B :NaOH, C :Éthanol, D : water) and a fifth (E :emulsifier) considered as an additive, on three properties of waterproofing concrete aged at least 28 days with knowing : capillarity, index of porosity and mechanical strength, is studied. This research allowed finding a compromise providing both a low capillarity and a low porosity and an acceptable mechanical strength of adjuvanted concrete.Voir les détails

Mots clés : Admixture, Waterproof, concrete, Mortar, Experimental Design.

Elaboration et caractérisation de nouvelles formulations améliorées des films à base de polymères biodégradables

Djalila AOUFI
Thèse de doctorat

Les matières plastiques synthétiques, dérivées de la chimie du pétrole, ont transformé notre quotidien. Cependant, l’emballage reste le premier domaine d’application du plastique. La production et l’utilisation de l’emballage à base de macromolécules d’origine pétrochimique en quantités continuellement croissantes se sont traduites par l’accumulation du plastique dans notre environnement, source de nuisance visuelle, par l’encombrement des décharges et par la pollution des sols et des milieux maritimes. Dans ce contexte, l’élaboration de nouveaux emballages biodégradables constitue une alternative très intéressante pour réduire le volume des déchets issus des matériaux d’emballage synthétique. Notre étude porte sur la synthèse et l’élaboration de nouveaux emballages biodégradables issus de ressources renouvelables. Ces derniers vont être caractérisés afin de pouvoir les utiliser comme de nouvelles formulations visant à produire des films destinés à l’emballage alimentaire.Voir les détails

Mots clés : emballages biodégradables, emballage alimentaire, polysaccharides .

Microstructure and mechanical properties of WC-Co / drill tool steel joints brazed using different thermal sprayed interlayers

D. Miroud, B. MAAMACHE, B. Cheniti, R. BADI (2016)

This paper examines the microstructure and the mechanical proprieties of WC-Co and low carbon steel joints obtained by Tungsten Inert Gas (TIG) brazing using two different thermal sprayed interlayers. On the connection zone, the characterizations of the WC–Co/interlayer/steel joints were studied by SEM, EDS and XRD. Microhardness measurements and shear test were made. The interlayer promoted the formation of interdiffusion zone, which possessed positive effects on the bond strength of the WC– Co/interlayer/steel joints. Having performed line and surface micro analyses of various zones, postbrazing diffusions of Co and Ni and other elements were determined. The hardness distribution in microhardness measurements on this zone shows the existence of element diffusion.Voir les détails

Mots clés : Tungstène carbide, steel, Interlayer bond, Thermal spray, Brazing


A.SERIER (2016)

Notre travail porte sur l’élaboration des films à base de polysaccharides et l’évaluation de l’influence d’un melange de plastifiants sur le comportement de ces films. Les films préparés par casting, pour différentes formulations, sont homogènes, opaques, minces et lisses, présentant une bonne cohésion et sans défauts visuels. Les caractéristiques physico-chimiques des films sont déterminées par différentes techniques (UV-visible, isotherme de sorption, perméabilité à la vapeur d’eau, et essais mécaniques en traction). les résultats obtenus montent que la combinaison des deux plastifiants a permis d’explorer les propriétés de chacun d’eux. Ça a donné naissance à de nouveaux films possédant de bonnes propriétés barrières contre les radiations lumineuses, une faible hydratation, une faible perméabilité aux vapeurs d’eau, une bonne stabilité thermique et une bonne flexibilité. Voir les détails

Mots clés : Mélange, plastifiants, biodégradables, polysaccharides, films.

Corrosion d’un multi matériaux soumis à un traitement thermique dans une solution d’H2SO

D. ALLOU, D. Miroud, B.cheniti, S.Bouyegh, A. Haddad (2016)

Nous nous sommes intéressés dans cette étude à caractériser des multi-matériaux élaborés par rechargement en utilisant le procédé de soudage manuel à l’électrode enrobée (SMAW), afin de mettre en évidence l’effet des conditions du cycle thermique imposés par le procédé sur la cohésion des interfaces, particulièrement du substrat-rechargement. Nous avons étudié le comportement électrochimique des différentes parties de l’assemblage en milieu H2SO4, et voir l'influence du traitement thermique sur ces variations. La caractérisation microstructurale a été évaluée en utilisant le microscope optique tandis que le comportement électrochimiques par un banc d’essai Potentiostatique et Potentiodynanmique. Le microscope électronique à Balayage pour évaluer le degré de corrosion et la composition du produit de corrosion.Voir les détails

Mots clés : Acier 25CD4, rechargement, caractérisation électrochimique, microstructure.