Métallurgie

Nombre total de résultats : 204
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Elaboration par pulvérisation cathodique magnétron de couches minces en vue de leur utilisation comme biomatériaux. Caractérisation à l’usure et à la corrosion.

Chems Eddine RAMOUL (En préparation)
Thèse de doctorat

Depuis les deux dernières décennies les prothèses orthopédiques (de genoux, de hanches..) fabriquées en alliages métalliques (alliage de titane, CoCrMo, aciers inoxydables…) sont recouvertes d’un dépôt de céramique (nitrures, oxydes…) ou en HAP (hydroxyapatite) dans le but d’accroître la bio réactivité de leur surface mais aussi leur résistance à l’usure et à la corrosion. Cependant le système interaction matière vivante/biomatériaux reste peu étudié et donc méconnu notamment le problème des infections toujours présentes. C’est précisément dans cette optique que se fera ce travail de doctorat. On se propose donc de développer de nouveaux matériaux ternaires ou quaternaires à base de Me (avec Me= métal tel Ti, Zr, Ag…) par pulvérisation magnétron sur divers substrats pour améliorer leur résistance à l’usure et à la corrosion, tribo-corrosion. Ces matériaux seront élaborés sous forme de couches minces par un dépôts physiques en phase vapeur. L’un des objectifs de ces travaux de recherche sera de vérifier s’il existe une relation entre les propriétés mécaniques et structurales des matériaux obtenus et leur comportement biologique. Voir les détails

Mots clés : biomatériaux, tribologie, corrosion

CHARACTERIZATION OF NATURAL DIATOMITE BY THERMAL ANALYSIS

H. MERADI, L. ATOUI, L. KOTBIA, S. BENAYACHE, W. Ghabeche, K. Bedoud, L. Bahloul (2017)
Article de conférence

Diatomite also called Kieselguhr obtained from the Sig deposit located in thewestward of Algeria, It is important to know the characteristics of diatomite beforeusing it. In this case, characterization was carried out by chemical, thermal analysisand scanning electron microscope. The results show that crude kieselguhr is formedof several components and in particular silica, alumina and calcium carbonates. It hasa extremely fine grained and highly absorbent material due to porosity over 72% andhas honeycomb like structure. The results obtained by simultaneous analyses,Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA) for calcineddiatomite at different temperature, showed the loss of mass when the temperature isincreased and revealed that the diatomite has four mass losses and showed differenttransformation (exothermic and endothermic) at different temperature.Voir les détails

Mots clés : diatomite, characterization, DSC, ATG

DRY WEAR TEST STUDY OF SUPERMARTENSITIC STAINLESS STEEL 13Cr5Ni2Mo FOR OIL AND GAS APPLICATION

C.E. RAMOUL, S. Meddah, S.Achouri, K. SLIMANI, M.I. Tlili (2017)
Article de conférence

Due to the increasing need for more cost-effective use of materials, supermartensitic stainless steels have been developed over the past 20 years and are ever more applied in the oil and gas industries to replace highly alloyed alternatives. In practice, the supermartensitic steels are used in the quenched and tempered state. In this study, we were interested in the frictional wear behavior of a supermartensitic stainless steel 13Cr5Ni2Mo, this steel intended for the manufacture of pipe used in the petroleum field. Several means of investigation have been used, namely thermal analysis by DSC on samples after homogenization treatment at 1050 ° C for 20 hours. The microstructure and the wear mechanism were studied using scanning electron microscopy. We choised a pin-on-disc tribometer under dry conditions against an Al2O3 alumina ball. All the tests were carried after quenching at 1050 °C and tempering at 550 °C, 2 hours (treatment which gave better hardness properties obtained by micro-indentation) at ambient temperature while varying the applied load of 2N, 6N to 10N. A one-off analysis of wear debris by EDS at SEM was also completed. The results obtained showed that the coefficient of friction of the 13Cr5Ni2Mo steel against the Al2O3 ball decreases with the decrease of the load. The mechanism wear observed in the SEM micrographs used surfaces is abrasive, adhesive, delamination and oxidation wear.Voir les détails

Mots clés : microstructure, 13Cr5Ni2Mo SMSS, wear, friction

DSC analysis of commercial Cu-Cr-Zr alloy processed by equal channel angular pressing

K. ABIB, F. HADJ LARBI, L. Rabahi, B. Alili, D. Bradai (2015)
Article de journal

Samples of a commercial Cu-1Cr-0.1Zr (mass fraction, %) alloy were subjected to equal channel angular pressing(ECAP) up to 16 passes at room temperature following route Bc. Differential scanning calorimetry (DSC) was used to highlight theprecipitation sequence and to calculate the stored energy, recrystallization temperature and activation energy after each ECAP pass.On another hand, electrical properties were correlated with the dislocation density. Results show that the stored energy increasesupon increasing ECAP pass numbers, while the recrystallization temperature decreases significantly.Voir les détails

Mots clés : equal channel angular pressing (ECAP), Cu-Cr-Zr alloy, differential scanning calorimetry (DSC), electrical conductivity, stored energy

Etude expérimentale et modélisation des cinétiques de transformation de phase dans un alliage de titane

Nabil KHERROUBA (2017)
Thèse de doctorat

The aim of this thesis is to experimentally study and to model the kinetics of α + β → β → αII phase transformations in Ti-6Al-4V alloy for isothermal and non-isothermal conditions. To this purpose, several technics have been performed (DSC, SEM, optical microscopy, in-situ electrical resistivity and XRD). The KM-JMA equation has been used to describe the kinetics of phase transformations during isothermal holdings. An approach based on the additivity rule has been developed to adapt the KM-JMA equation to non-isothermal phase transformations and is compared to the one using the fictitious time. Kinetics parameters (n, k and Q) have been determined using this approach and discussed based on the microstructural analysis. Mechanisms of the α + β → β → α phase transformations have been discussed by considering the microstructural analysis and the kinetics parameters already determined. Finally, the βm → αII phase transformation kinetics in isothermal conditions has been simulated with the MatCalc software and modelled using both the nucleation – growth theory and the KM-JMA equation. Voir les détails

Mots clés : Ti-6Al-4V, KM-JMA, additivity, nucleation – growth

Characterization and Microstructural of HotRolling Mill Scale

B. Maalem, A. BALASKA, A. HAMOUDA, S. Djemili (2017)
Article de conférence

In the IMETAL-El Hadjar complex, during the steel manufacturing process, a significant amount of scale is produced on the surface of slabs and billets of hot-rolled steel. In the various rolling mills, the quantity of scale produced is estimated to be about 0.1% of the annual production of the steel complex. The quality of the thin steel sheet during the rolling process is affected by the behavior of the iron oxide layers formed on their surfaces (scale).This amount of scale which is a fatal by-product of the forging and rolling processes can be reused in certain areas and applied by appropriate recycling techniques such as agglomeration of iron ores in the blast furnace as a raw material. This aspect of recycling is taken into consideration.The objective of this study is to identify the microstructural properties of the scale, using different analytical methods such as X-ray diffraction and scanning microscopy.Several samples were used for characterization of the locally produced scale.The analyzes of the results given by SEM showed that hematite and magnetite, the main phases present in the scale, are stacked in thin layers of a magnitude of the order of a micron meter. These phases of iron oxides are confirmed by the analysis of the spectra given by the X-ray diffractometer.The presence of silicon in the scale is due to the covering powder used on the wall layers of the ladles.Voir les détails

Mots clés : mill scale, Oxidation, hot rolling, Microstructural properties, SEM, X-ray

Résistance à la corrosion des joints soudés par le procédéTIG, d’un assemblage hétérogène 304L /A9étamé, dansNaCl 32g/l.

Badr Eddine MAALEM (2015)
Mémoire de magister

The heterogeneous welding of extra-soft steel A9 and a rustproof austenitic steel AISI304Lhas been achieved by the TIG process (autogeneous welding).Soldering have been made in the goal to substitute the mechanical assembly (clinch, bolting)in certain applications. In the other hand, to value the resistance to the corrosion of jointswelded to certain types of corrosion galvanic coupling for example.Three profiles have been achieved; the two welded separately the extra-soft steel A9 andrustproof austenitic steel AISI304L then together steels.A comparison of corrosion parameters (speed of corrosion, potential and current of corrosion)of the three profiles shows that the heterogeneous joint is good resistant in a saline solutionaired without agitation to 32g/l NaCl that homogeneous assembly A9. Voir les détails

Mots clés : heterogeneous welding, TIG, galvanic corrosion, rustproof steel.

Elaboration de fonte au cubilot. Impct sur l'Environnement.

Mohamed Tayeb ABEDGHARS (2012)
Mémoire de magister

Les exigences en matière d’écologie sont de plus en plus imposées par le législateur. Les fonderies de fonte, utilisant le cubilot comme moyen de fusion et plusieurs autres matériaux pour la confection des moules et des noyaux, produisent une grande quantité de gaz polluant et de poussière. Ces polluants sont rejetés dans l’atmosphère et sont très néfastes pour la santé humaine des travailleurs et de l’environnement avoisinant les sites de production.De ce fait, notre étude porte sur la caractérisation d’une fonte produite par le cubilot d’une part et le monitoring des gaz polluants tels que: le SO2, les NOx et les BTX en continue pendant un poste de travail par des capteurs passifs d’autre part. La mesure du taux de poussière régnant dans les différents ateliers de la fonderie est réalisée par la méthode de décantation (méthode de Bergeroff). Tous ces polluants sont connus pour leur impact nocif sur la santé humaine.Les objectifs stratégiques visés par cette étude sont de répertorier les émissions atmosphériques, déterminer le niveau de la pollution atmosphérique générée par l’activité d’une unité de production de pièces coulées en fonte utilisant comme appareil de fusion le cubilot et comme moulage le procédé classique, déterminer les pics de concentration des gaz polluants (SO2, NOx et BTX), quantifier et analyser la pollution par les particules en suspension, élaborer une cartographie de la pollution atmosphérique et comparer les valeurs obtenues relatives à la situation actuelle aux valeurs limites de l’OMS.Des essais de caractérisation de la fonte produite au niveau de la fonderie de l’Ouenza nous ont permis de constater qu’il s’agit d’une fonte grise courante de structure perlitique avec graphite lamellaire. La présence du phosphore en quantité supérieure à la limite admissible est sous forme d’eutectique phosphoreux.L’analyse chimique a montré la présence du cuivre en faible quantité, ce dernier est considéré comme un élément perlitisant et durcissant.Les résultats des mesures effectuées ont montré une très forte pollution atteignant des valeurs de 236.6µg/m3 pour le benzène (C6H6), 508.2µg/m3 pour le dioxyde de soufre (SO2) et 722.4µg/m3 pour les oxydes d’azote (NOx). Les concentrations en poussières sont en deçà de la valeur limite de l’OMS. Leur analyse chimique a montré la présence de beaucoup de silice et de fer. Voir les détails

Mots clés : fonte, cubilot, Environnement, OMS, pollution air, particules, santé

Beta to alpha transformation kinetics and microstructure of Ti-6Al-4Valloy during continuous cooling

Nabil KHERROUBA, Mabrouk BOUABDALLAH, Riad BADJI, Denis CARRON, Mounir AMIR (2016)
Article de journal

In the present paper, an approach based on the Kolmogorov-Johnson-Mehl-Avrami (KJMA) model hasbeen developed and applied to study the transformation kinetics of the b phase in Ti-6Al-4V titaniumalloy during cooling. To this purpose, Differential Scanning Calorimetry (DSC) tests have been conductedusing a set of cooling rates ranging from 10 to 50 C/min. This approach allows the kinetics parameters,particularly the activation energy, to be calculated from a single DSC test using a simple linear regression.The microstructural analysis indicates that the microstructure is dominated by the a Widmanstatten €morphology (aW). Microstructural observations along with the calculated values of the Avrami index andof the activation energy suggest that the growth of the aW platelets obeys a mixed mode combining thevanadium diffusion and a displacive mechanism.Voir les détails

Mots clés : Continuous cooling, KJMA model, additivity rule, diffusion, Displacive mechanism

Study of kinetics phase transformations during continuous heating and cooling in Ti-6Al-4V

Nabil KHERROUBA, Brahim MEHDI, Lyacine RABAHI, Riad BADJI (2017)
Article de conférence

The aim of this work is to investigate the effect of the solution treatment temperature on the β → α during continuous cooling from temperatures above the transus β in the Ti-6Al-4V titanium alloy. The microstructural analysis reveals the nucleation of two morphologies of α phase: αGB layer that nucleates along the β/β grain boundaries and αW platelets nucleating from the αGB layer or directly on the β/β grain boundaries. An increase in the solution treatment temperature causes a β grain coarsening and delays the formation of the α phase. An approach based on the additivity rule to adapt the KJMA equation to non-isothermal phase transformation has been used to determine the kinetics parameters. This approach permits also to study the α + β → β phase transformation kinetics during continuous heating. This parameters have been discussed according to the microstructure evolution.Voir les détails

Mots clés : Ti-6Al-4V, additivity rule, KJMA equation, sympathetic nucleation