Sciences et génie des matériaux

Nombre total de résultats : 87
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Etude D’efficacité D’inhibiteur NALCO E1154A Sur L’acier A36 Utilisé Dans Les Bacs De Stockage Des Hydrocarbures Du Site GTFT-ILIZI

Mémoire de Master

The corrosion of the condensate and LPG storage tanks in the GTFT zone presents a major problem that leads to a degradation of the storage tanks where huge sums are spent annually to protect the structures against corrosion, The maintenance and repair of the storage tanks. storage systems go through a detailed inspection program in order toobtain the data necessary to be properly adapted, today corrosion protection includes treatments such as cathodic protection, surface treatments or even the modification of the corrosive environment by addition of corrosion inhibitors. These constitute an original means of combating corrosion.In order to test the effectiveness of NALCO 115 EC 1154A inhibitor on A36 steel for use in the protection against corrosion of storage facilities for hydrocarbon products inthe GTFT zone, we were interested in this study to seek the optimal concentration in order to perform electrochemical tests. Voir les détails

Mots clés : corrosion, storage bins, inhibitors, A36 steel

Préparation et caractérisation des nanoparticules de ferrite de nickel dopée au Cérium par la méthode de coprécipitation

A. TALBI, A. SALHI  (2020)
Mémoire de Master

Nanocrystalline powders of cerium-doped nickel ferrite were synthesised by the coprecipitation method and the effect of the non-magnetic cerium content on the structural and magnetic properties was studied. X-ray diffraction (XRD) was used to determine the structure of NiFe2O4 nanoparticles. The surface morphology and chemical composition of the NiFe2O4 nanoparticles were obtained by scanning electron microscope analysis. The magnetic properties were studied by Vibrating Sample Magnetometry (VSM). Magnetic hysteresis cycles were measured with a maximum applied magnetic field of ≈ 1000Oe Voir les détails

Mots clés : NiFe2O4, cerium, co-precipitation, Magnetic Properties, DRX, SEM, VSM

Mise en œuvre de l’essai de fatigue sur des alliages d’aluminium

S. BENRABAH  (2020)
Mémoire de Master

The problem of fatigue of structures is commonly present in all sectors of the maritime, aeronautical, and mechanical and many other industries. In order to fully understand this harmful phenomenon, tests of different types of stresses are carried out at the laboratory level. This requires a good mastery of the test protocol. The analysis of the results obtained by these tests allows to study the behavior of the material. Our study consists in the implementation and the determination of the operating conditions of a uniaxial fatigue test with two types of specimens made of aluminum alloys of different thicknesses are tested. A tensile test is carried out to determine the mechanical behavior of the specimens and to have the necessary parameters to carry out a fatigue test, a metallographic study to characterize the specimens before carrying out the fatigue test. All the results obtained from the test are in the form of curves and a hysteresis loop. Voir les détails

Mots clés : Fatigue test, fatigue of aluminum, aluminum’s alloys

Élaboration et caractérisation des céramiques supraconductrices YBa2Cu3O7

Mémoire de Master

This work presents bibliographic research and generalities about superconducting materials. The polycrystalline superconducting compound Y123 was developed by solid state reaction (powder metallurgy) from stoichiometric mixtures Y2O3, BaCO3, and CuO. To study the effect of the addition of lanthanum-doped cobalt ferrite (0-5-10%) on magnetic and optical properties, samples of 2g (99.9% Y123 and 0.1% CoFe2O4 (0-5-10%) lanthanumdoped) were prepared, and characterized by VSM and FTIR. Voir les détails

Mots clés : cuprates, supraconducter, Y123, YBCO, magnetic

Etude des propriétés mécaniques et magnétiques des alliages Fe70Al30-xSixélaboré par arc melting

M. CHETTAH  (2019)
Mémoire de Master

This study investigates the effect of Al substitution by Si on the structural, mechanical (Vickers HV hardness) and magnetic (hysteresis loop) properties of the Fe70Al30-xSix alloys developed by Arc Melting.Results show that the increase in Si content gives rise to the ordered phase DO3 (FeAl0.7Si0.3) starting from the composition Fe70Al15Si15; this last transition is accompanied by a drop in micro hardness HV and a remarkable variation in structural parameters such as relaxation of the crystals. Also, the substitution of Al by Si atomes decreases the cell parameter.Our choice of process and alloy is based on economic considerations (low cost) to understand the phase transitions in these alloys that are typical ones. Voir les détails

Mots clés : Fe-Al-Si alloys, Arc melting, Order-disorder transitions, solid solution bcc-Fe, Ordered phase DO3 (Fe3Al0.7Si0.3), micro-hardness HV, Hysteresis cycle, Coercive field, Remanent magnetization, Saturation magnetization

Étude ab-initio dans le cadre de la DFT des propriétés structurales et physiques de supraconducteur à haute température critique (SHTc) de type pnictides de fer (FeSe)

M. CHETTAH  (2019)
Mémoire de Master

In this work, we presented a study on the structural, elastic, electronic, magnetic and optical properties of iron selenide. The calculations were performed by the Pseudo-Potential method which is based on density functional formalism (DFT), using local density (LDA) and generalized gradient (GGA) approximations. The doped (GdFeSe and CeFeSe) and undoped (FeSe) structural properties such as the mesh parameters (a, b and c) and the compressibility modulus, are calculated as a function of pressure and the results found are in agreement with those advanced by the experimental and other calculations. In the study of the electronic properties of FeSe, the energy gap value calculated with the GGA approach are in agreement with those of other calculations. As far as the elastic properties are concerned, we calculated the elastic constants with the GGA approach and the found values of the latter are very close to those of the experiment. We also calculated the magnetic moment and confirmed that FeSe is a non-magnetic material. For the optical properties, we calculated the different optical properties such as the function of the reflectivity, the refractive index and the absorption coefficient. Voir les détails

Mots clés : Superconductivity, pnictures, FeSe, DFT, pseudo potential, Castep

Etude expérimentale des vitesses et d’atténuation d’un polymère semi cristallin PEHD par des méthodes ultrasonores

R.Daha, D.Chehaoui  (2019)
Mémoire de Master

Semi-crystalline polymers are materials that permeate our daily lives, and are used in a wide range of applications, generally when viscoelasticity is required. Therefore, numerous works of research have been conducted these last years to study their elastic properties. Since then, we propose the use of nondestructive analysis techniques based on detecting and spreading ultra sound waves with both immersion and contact. The results obtained on the analyzed materials presents us with good estimates judged to be very satisfying compared to literature. Measures of the velocity and mitigation of longitudinal and transverse ultra sound waves have been conducted on two samples of different thickness of a semi-crystalline polymer of the type PEHD. The experiments have been conducted in ambient temperature. The objective is the characterization of this polymer using ultra sound waves. Voir les détails

Mots clés : Ultrasounds, Velocity, Attenuation, echoes, transmission, polymers.

Effet de déformation par pliage sur le comportement à la corrosion de l’acier duplex 2205

M.Meyssoune, K.MENNA  (2019)
Mémoire de Master

The effect of cold deforming by folding on the microstructure and corrosion behavior of austenoferritic stainless steel (duplex 2205) has been studied in this work. Duplex 2205 offers a good compromise between the toughness of austenitic steels and the mechanical and corrosion resistance of ferritic steels. We deformed the duplex steel by bending it at different levels (12, 25, 40 and 50%). The effect of the deformation on the microstructure and mechanical properties was investigated by the various experimental technics; microhardness; metallography, SEM. The relationship between increasing deformation and corrosion resistance was investigated by electrochemical tests. The results showed that cold working modifies the internal microstructure of both phases and that high cold forming rates have a detrimental effect on the corrosion resistance of duplex steels. Voir les détails

Mots clés : deformation, duplex, corrosion, Austenite, Ferrite, Resistant, Folding

Synthesis of Lead-Free Ceramicsof the Perovskite Type for PiezoelectricApplications by Conventional Solid-StateReaction

K. Sedda, R. Djafar, K. Boumchedda, F. Boukazouha, M. Latef  (2020)

Structural properties of BaTiO3, CaTiO3 and Ba0.85Ca0.15Ti0.9Zr0.1O3 prepared by conventional solid state reaction technique, at different calcinations temperatures 1100, 1150 and 1280 °C and sintering temperatures (1200and 1300 °C) are studied. These compositions were selected because of theirinteresting piezoelectric properties. To follow the decomposition process of theprecursor, a differential thermal analysis coupled with thermogravimetric analysis (ATG-ATD) was performed. Structural parameters are analyzed by X-raydiffraction (XRD) and scanning electron microscopy (SEM). The obtained resultsshowed clearly the synthesis of the perovskite phase. The diffractogram illustratesthat BCTZ symmetry is both cubic with a Pm-3 m space group and orthorhombic with a R3m space group, the calculated phase rates are respectively 10% and90%. The results allowed us to specify the effect of sintering temperatures on thestructural properties of ceramics. Voir les détails

Mots clés : Lead free ceramics, synthesis, ;, microstructure, Perovskite

Cu2O addition and sintering temperature dependence of structural,microstructural and dielectric properties of CaCu3Ti4O12 ceramics

R. Djafar, K. Boumchedda, A. Chaouchi, D. Fasquelle, K. Sedda, S. Brahimi, K. Khalfaoui, M. Bououdina  (2020)

This study is aimed in the replacement of commonly used (CuO) by Cu2O in the synthesis of perovskiteCaCu3Ti4O12 (CCTO) phase by the solid-state reaction method. The XRD analysis of powder calcined at 1100 ?Cand ceramics sintered at different temperatures show that the CCTO phase was well crystallized with thepresence of small quantities of additional phases. The SEM/EDS analysis of prepared pellets show that the formation of Cu2O/CuO phase occurs above 950 ?C, resulting in enhanced densifcation at 1050 ?C (>96%).However, it is found that the Cu2O-based CCTO begins to degrade around 1090 ?C. The densifcation aftersintering at 1050 ?C reaches 96%, meanwhile dielectric constant and loss tangent values are optimum in the lowfrequency range (<103 Hz); i.e. 13378 and 0.177, respectively. This favors the use of Cu2O instead of CuO inCCTO ceramics for applications at low frequencies. Voir les détails

Mots clés : Ceramics, CCTO, powder metallurgy, XRD and SEM, Dielectric properties