Métallurgie
Physical and chemical analysis of the material cast of a prosthesis for tibia (morphology and DSC).
In this approach, we have shown the results of Scanning Electron Microscope characterization (SEM), Optical Microscopy and Differential Scanning Calorimetry (DSC). The prosthesis is a composite material consisted of an organic matrix reinforced by a glass fiber and perlon, prepared by a standard casting method under vacuum. All our results show us: -The microscopic analysis has a porous structure. -Furthermore, the optical micrography chows the arrangement of the fiber in the matrix. -The result of Differential Scanning Calorimetry shows a glass transition (Tg). Voir les détails
Mots clés : physical analysis, prosthesis for tibia, MEB, DSC, optical microscopy.
DETERMINATION DES PARAMETRES NANOSTRUCTURAUX A BASE DE FeX CoY NiZ ET ALLIAGES PAR DES METHODES DE CONTROLES NON DESTRUCTIF (CND).
L’élaboration des nanomatériaux a connue une évolution ces dernières années, Les nanomatériaux présentent le plus souvent des comportements originaux et des propriétés qui diffèrent considérablement de celles des matériaux massifs de même composition chimique.Il existe plusieurs méthodes d’élaboration des nanomatériaux,la mécanosynthèse (broyage mécanique) a été découverte à la fin des années 80, elle est révélé être une technique intéressante pour provoquer une variété de réactions à l’état solide comme:l’amorphisation, les transformations allotropiques, la formation de solutions solides, lesréactions chimiques .L’objet de notre travail consiste dans l’analyse des nano poudres obtenus après des transformations par mecano synthèse et d’étudier leur comportement physiquesNous avons choisi dans notre travail le système Fe-Co, Il est lié au fait que ce dernier constitue la base d’aimant permanent d’une part et son utilisation dans diverses applications d’autre part.L’élaboration de l’alliage Fe80Co20 par broyage mécanique d’un mélange de poudres de fer et de cobalt a été la première étape, la deuxième étape consiste à caractériser les éléments obtenus par le Control non destructif (CND). L’utilisation du diffraction des rayon X (DRX) et Microscope électronique a balayage (MEB) permet de vérifier les résultat obtenue par CND.Entre autre il a été confirmé que l’étude par diffraction de rayons X met en évidence la formation de l’alliage Fe-Co après seulement 15 heures de broyage et une taille moyenne des cristallites de 15 nm après 40 heures de broyage.Le traitement des courbes d’aimantation des alliages Fe-Co obtenus, montrent des propriétés magnétiques originales : comportement super paramagnétique, et surtout une aimantation à saturation et une coercitivité importante. Voir les détails
Mots clés : Fe Co Ni nanostructuré, Mécano synthèse, cnd, Métallurgie de poudre
ÉTUDE DES PROPRIÉTÉS THERMIQUES DES BATTITURES DU LAMINOIR À CHAUD COMPLEXE SIDERURGIQUE El-HADJAR-ANNABA
Les battitures de laminoir à chaud du complexe sidérurgique d’El-Hadjar-Annaba représentent 0,1% de la production annuelle des produits plats laminés causant des pertes qui peuvent être valorisées dans certains domaines d’application.A priori, nous avons étudié les propriétés thermiques des battitures provenant du laminoir à chaud. La formation de ces battitures au cours de laminage dépend de plusieurs facteurs métallurgiques, en particulier la température dans le four de réchauffage, la pression partielle des gaz dans les différentes zones du four poussant, le temps de séjour à l’intérieur du four etc…L’analyse thermique par DSC et TGA montre des pics exothermiques synonyme d’une déshydratation et déshuilage de la calamine et des pics endothermiques indiquant une éventuelle recristallisation des oxydes de fer en l’occurrence FeO qui est stable au-delà d’une température de 570°C. Voir les détails
Mots clés : Battitures, oxydation, Laminage, Propriétés thermiques, DSC-TGA
Elaboration et Caractérisation des Revêtements durs de Molybdène et des Couches Nitrocarburées Déposés sur une Fonte Grise
Pearlitic gray cast iron with lamellar graphite characterized by a better wear resistance and low friction coefficient used in the majority of cases in engineering are exposed to some very demanding operating conditions, being particularly significant thermal stresses, the abrasive wear and damage by corrosion of external parts. The present study was conducted with the main objective to study the effects of two different surface treatments to improve the microstructure and there fore anti-wear properties and electrochemical of cast iron in order to minimizing a weight loss. To answer our objectives and for first phase, we have chosen a surface hardening treatment by deposition of molybdenum with a thermal flame spraying process. Considering the diversity of parameters such as the surface pretreatment, the roughness, the flame temperature ,the distance between nozzle and substrate, gas pressure, the torch speed ,we were able to obtain a deposit thickness of 780 microns and roughness about 10 microns. This molybdenum coating is characterized by a lamellar structure containing oxides types (MoO3, Mo9O26, and Mo4O11), pores and unmelted particles. However, the contribution of molybdenum with the flame-wire process led to the formation of an interdiffusion zone can form intermetallic reinforcing coating-substrate adhesion. This treatment caused an improvement in the surface hardness up to 1400 HV. This value of hardness was also confirmed by nanoindentation testing where we found the elastic properties such as Young's modulus and Poisson's ratio. Besides, this coating is characterized by improved wear resistance and corrosion in chloride medium with 3 2 g/l relatively to the substrate. In the second phase of this study, we propose a treatment salt bath ferritic nitrocarburizing at a temperature of 580°C by varying the diffusion time from 2h up to 6h. The optimal hardening was obtained at temperature 580°C for 6h. This treatment has allowed us to obtain a nitrocarburized layer composed mainly of a compound layer (ε-Fe2-3N and γ'-Fe4N) followed by a diffusion layer (α and carbides). These layers a few tens microns of thicknesses have created a level of extreme hardness surface about 750 HV. Similarly, resistance to wear and corrosion in chloride solution at 32 g/l are significantly improved compared to those of the substrate.The analysis of the microstructure, mechanical, electrochemical behavior of coated systems and nitrocarburized layers were made using analysis techniques such as optical microscopy and scanning electron microscopy, grazing incidence X-rays diffraction, microanalysis of elements, Vickers microhardness, nanoindentation, testing abrasion and finally the electrochemical tests. Voir les détails
Mots clés : traitement de surface, projection thermique, Nitrocarburation, Revêtement Mo, propriétés mécaniques, fonte grise
ETUDE DES PROPRIETES MECANIQUES DES COUCHES DE MOLYBDENE PROJETEES THERMIQUEMENT SUR UNE FONTE GRISE
The coatings obtained by thermal spraying are used in order to meet the most stringent industrial requirements in the fields of application wider. The molybdenum coating is one good wear resistance which used in several mechanical applications. In this work, we have studied the mechanical properties of molybdenum coating deposited using thermal spraying on gray cast iron with lamellar graphite. After optimization of spraying parameters, the microstructure has been studied using the optical microscopy, scanning electron microscopy and the X-ray diffraction. Also, the mechanical properties such as microhardness and elastic properties like elastic modulus using nanoindentation test have been evaluated on cross section sample polished. The weight loss has been studied using the abrasive wear test varying the normal load. The results obtained have showed an improvement the mechanical properties of gray cast iron after deposit of molybdenum. Voir les détails
Mots clés : Thermal Spraying, Molybdenum Coating, gray cast iron, wear, mechanical properties
Microstructural and mechanical properties of WC-Co/1020 steel joints obtained by oxyacetylene and TIG brazing process
In this work, the microstructure evolution and the mechanical behavior of WC-Co / 1020 steel joint obtained by oxyacetylene and tungsten Inert Gas (TIG) brazing process are investigated. The maximum peak temperature induced by TIG process and the introduction of shielding gas causes a remarkable inter-diffusion at WC-Co/braze interface. The diffusion of Co Towards the braze in the interface obtained by TIG process is greater compared with the oxyacetylene ones. On the other side, a short range diffusion of Ni towards the WC-Co is observed. This phenomenon leads to create a new zone devoid in Co elements with high WC particle concentration at WC-Co/braze interface using TIG brazing process. The mechanical behavior is carried out through shear and micro-hardness test, they show that the presence of the new zone concentrated in WC particles beside the hard metal, makes the joint less strong than the one obtained by the oxyacetylene brazing, despite the inter-diffusion of Co and Ni elements in the interface. However, special shear test (SST) reveals that the joint made by the TIG process is resistant as much as the oxyacetylene brazing one. Voir les détails
Mots clés : WC-Co cermet, TIG brazing, Interface, inter-diffusion, mechanical behavior
Evaluation and Chemical Analysis of Particulate Pollution in the Ironworks Site of El-Hadjar
The air that we breathe today is a mixture more or less polluted by location where we are. This mixture of pollutants generating significant and sustainable threats to human health, especially respiratory problems .The environmental concern is becoming increasingly strong, driven in particular by the current debate on sustainable development that is mirrored various international conferences [1] .Also theeffectson a global scale are warming the atmosphere and therefore the Earth, or the destruction of the ozone layer. The air quality management contributes to the mastery of a better knowledge of the pollution generated by the steel industrial activity. This investigation is the first national enterprise approach to the management of environmental problems on an industrial scale, more particularly in the steel sector. Taking into account these principles, it is appropriate to follow the pollution by suspended particles in and around the steel complex of El Hadjar.The objectives of this work are:Knowledge Of highest concentration level of dust inside and outside the workplace. Evaluation Compared to WHO limits values [2] and European Directives [3];[4]. Determination Of heavy metals in dust fallout.For the choice of measurement sites, a clipping entire surface of the steel complex was carried out by a method called mesh. This method we devoted 19 measurement sites. The sampling method used is that of BERGHEROFF. Indicators are the overall amount of dusts deposited chemical analysis elements such as Cr, Cu, Zn, Ni, Pb and Mn [4]. The quantities of dust are analytically weighed and then analyzed atomic absorption analytical chemistrySuspended particles that contaminate the air are the main carriers carry in the wind various polluting compounds (SO2, Cu, Pb, H2SO4, NH3 ...) [3]. At PMA 2, calculations show is discharged 4509 m3 per ton of fumes sinter. The results showed measurement sites S2, S3, S4, S5 and S18 are large emissions dusts. These sites except S18 represent the hot zone of complex. According Opair,the incidence of values of the measured dust on the sites is all above the limit value. For heavy metals in the dusts, there is a high concentration of zinc in all sites. Knowing that is neurotoxic and carcinogenic Pb is present in large quantities with a peak in S3. For S11 and S17 its value is close to the norm. The chromium and nickel both carcinogenic move in the same direction with alarming values. Voir les détails
Mots clés : Air pollution, dust emission, particulate fallout, TPS, method Bergeroff, heavy metals.
Characterization of diatomitefrom Sig region (West Algeria)for industrial application
Diatomite also known Kieselguhr, is a non-metallic mineral composed of the skeletalremains of microscopic single-celled aquatic algae called diatoms. The purpose of this paper is to testand to evaluate the diatomite of Sig region (West Algeria) to substitute the main mould powder used incontinuous casting of steel for thermal insulation and lubrication.Design/methodology/approach – To assess the behavior of diatomite at different temperatures,a combination of simultaneous scanning calorimetric and thermogravimetric testing was used and toevaluate the structure of diatomite, the scanning microscopy method was applied.Findings – The results showed different endothermic and exothermic peaks, mainly at 84.7°C and783.5°C for endothermic peaks and 894.9°C for exothermic peak. The scanning microscopy methodwas used and a large porosity was observed. The trial industrial in continuous casting of steel showeda weak loss temperature of steel.Originality/value – This product may be used for thermal insulation in continuous casting of steel.Also the characterization showed the hot behavior of this product with the various transformationsand could give the possibility to other use Voir les détails
Mots clés : diatomite, fluorine, lubrication, Mould fluxes, thermal insulation
PROCEDE "TENIFER" ET CARACTRIPROCEDE "TENIFER" ETCARACTRISATION EN STRUCTURE ETDURETE DE DEUX NUANCES Z60CDV5 etZ100CDV5.
l'optimisation d'un traitement superficiel de durcissement par nitruration nécessite la prise en compte de nombreusesparamètres afin d'améliorer la résistance de l'usure de l'outil. On cite la microstrucure initial du matériau , induite par le traitementpréalable ( trempe et récuit) considéré comme éssentielle. l'homogénéité de la structure présente une caractéristiques des aciers . Lacouche nitrurée à 570° permet d'augmenter considérablement les qualitées de fottements et de résisstance à l'usure.Keywords : nitruration, traitement superficiel, résistance à l'usure Voir les détails
Mots clés : nitruration, traitement superficiel, résistance à l'usure
IMPROVING WEAR PROPERTIES OF HIGH-CHROMIUM CAST IRON BY MANGANESEALLOYING
High-chromium cast irons are widely needed by severalindustrial areas where wear is the dominant environment.They are used in mining, cement- and steel-making plants,and many others. Their microstructure consists of nettedeutectic carbides embedded in an austenitic or martensiticmatrix. The wear behaviour is mainly controlled by thecarbides shape and also matrix type. Several scientificworks try to improve the wear behaviour and to optimizethe life service of this cast iron by using various techniques.In this work, we intend to study the effect of manganesecontent on the microstructure properties and wearbehaviour of a 15 % chromium white cast iron used forball mill production. The present work treats the wearbehaviour, after heat treatment, of a manganese-alloyedhigh-chromium cast iron. A set of specimens were melted inan induction oven by varying the manganese content in therange 0–3 %. Heat-treated samples were analysed byoptical microscopy, MEB (SEM) scanning electronmicroscopy, differential scanning calorimetry, and X-raydiffraction and were wear tested by abrasion and friction.Increasing the manganese addition gave a structural evolutionand a wear resistance improvement. The best wearbehaviour is obtained with samples containing 3 % Mn. Voir les détails
Mots clés : Chromium cast iron, carbide-forming elements, eutectic carbides, secondary precipitation, abrasion, friction