Liste des documents

Nombre total de résultats : 1976
Pertinence Titre A-Z Plus récents Plus anciens
10 25 50
Année de publication


BOUCHOUL Bousaha (2011)
Mémoire de magister

health starts several research to replace them by bio plasticizers, for that we studied the possibility of using the di ester isosorbide (DEI) and sunflower oil epoxydized as bio plasticizers. We manufactured PVC films containing various rates of DEHP, DEI and HTE. Then we carried out the analyses for the study of the mechanical (traction and hardness), thermals (coloring, TGA and DMA) and physic-chemical properties (volatility, extraction and leaching) according to change of the rate and the type of plasticizer. The results obtained show that the HTE has better thermal properties but very bad mechanical properties and physic-chemical, the DEI having almost the same properties or better than the DEHP. Voir les détails

Mots clés : PVC, DEHP, DEI, HTE, bio plasticizers, Volatility, extraction, leaching.

Mechanism for phosphorus deactivation in silicon-based Schottkydiodes submitted to MW-ECR hydrogen plasma

Article de journal

Current work reveals the deactivation mechanism of phosphorus in silicon-based Schottky diodes. Microwave plasma power(P) was fixed at 650 W to observe the variation in different operational parameters of diodes such as initial phosphorusconcentration, flux and hydrogenation temperature (TMWH) and process time (t). The analysis of variation in concentrationof phosphorus by hydrogenation has been carried out by capacitance–voltage (C–V) measurements to monitor the dopingactivation/deactivation. The results clearly show that the atomic species H+H is dominant in the reactors MW-ECR plasma.Therefore, the rates and depth of neutralization were obtained in the low phosphorus-doped silicon sample. The H becomesH0 and prefers an interaction with another H0 instead of gaining an electron to become a negative ion. The hydrogenationtemperature study indicates that the deactivation rate of phosphorus is achieved in a complex manner. Indeed, as the hydrogenationtemperatureincreases,deactivationof phosphorus also increasestill saturationat 250 °C.Athigher temperature,lowor evenno phosphorus–hydrogen complexexistsdue totheirthermaldissociation. The same behaviorwasconfirmedbylonghydrogenation.Voir les détails

Mots clés : MW-ECR plasma, Hydrogenation, phosphorus deactivation, C–V measurement

Synthesis and characterization of nickel nanoparticles supported on aluminum oxide

D.BELFENNACHE, A.Boulegane, D.Lakhdari, N.KAGHOUCHE (2019)
Article de conférence

Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure. In recent years, many research fields have focused on the synthesis of nanoscale-sized metallic materials with complex shape and composition in order to optimize the optical and electrical response of devices containing metallic nanostructures. In This work, we study nickel nanoparticles supported on aluminum oxide, prepared by impregnation with ionic exchange. In a first stage, the fixing conditions of the nickel precursor on aluminum oxide are optimized. In the second stage, the samples are calcined at temperature (T= 750 °C). Several experimental techniques are used for the characterization of the samples at the various stages of their elaboration (SEM, DRX, and VSM). A change of morphology of the aluminum oxide grains was observed by Scanning Electron Microscope. The X-rays diffraction shows the formations of nanoparticles Al3Ni2 of near size 16.7 nm. The extracted magnetic measurements show the good and the easy magnetizationVoir les détails

Mots clés : nanostructures, Ionic exchange, Nickel nanoparticles, calcination

Modeling of dual-junction tandem based on InGaP/GaAs heterojunction stacked on a Ge solar cell

F. Bouzid, F. Pezzimenti, L. Dehimi, F.G. Della Corte, M. HADJAB, A. HADJ LARBI (2019)
Article de conférence

In this work, an analytical model is used to describe the elctrical characteristics of a dual-junction tandem solar cell performing a conversion efficiency of 32.56% under air mass 1.5 global (AM1.5G) spectrum. The tandem structure consists of a thin heterojunction top cell made of indium gallium phosphide (InGaP) on gallium arsenide (GaAs), mechanically stacked on a relatively thick germanium (Ge) substrate which acts as bottom cell. In order to obtain the best performance of such a structure, we simulate for both the upper and lower sub-cell the current density-voltage, power density-voltage, and spectral response behaviours taking into account the doping-dependent transport parameters and a wide range of minority carrier surface recombination velocities.For the proposed tandem cell, our calculations predict that optimal photovoltaic (PV) parameters, namely the short-circuit current density (Jsc), open-circuit voltage (Voc), maximum power density (Pmax), and fill factor (FF) are Jsc= 28.25 mA/cm2, Voc= 1.24 V, Pmax = 31.64 mW/cm2, and FF = 89.95%, respectively. The present study could turn useful to support the design of high efficiency dual junction structures by investigating the role of different materials and physical parameters.Voir les détails

Mots clés : Analytical modeling, tandem solar cell, Spectral response, conversion efficiency

Poly Chlorure de Vinyle (PVC) Plastifié par des Mélanges des Plastifiants d’origineBiosourcés : Synthèse et Caractérisation

Boussaha BOUCHOUL, Mohamed Tahar BENANIBA (2016)
Article de journal

L’huile de tournesol époxydée (HTE) avec un indice d’oxyrane de 4,5 a été synthétisée à partir de l’huile de tournesol vierge et l’eau oxygénée (H2O2) en présence de l’acide formique. L’HTE est utilisée avec le di esters isosorbide (DEI) comme un système plastifiant biosourcé dans le PVC en combinaison avec un plastifiant classique soit le di-éthyle-2-hexyle phthalates (DEHP).Après fabrication des films (0,5 mm d’épaisseurs) de différents pourcentages des plastifiants dans un mélangeur à deux cylindres, on a réalisé les essais de la migration et d’excudation des plastifiants des formulations obtenues. La migration des plastifiants biosourcés (DEI ou HTE) en combinaison avec le DEHP est suivie par les tests de volatilité, d’extraction et de lessivage. Les pertes des masses des formulations plastifiées réalisées obtenues par les différents modes de caractérisation à savoir: la volatilité, l’extraction dans l’eau distillée et dans la gazoline et le lessivage dépendent de la pression devapeur, de la masse moléculaire, de la solubilité, de la compatibilité et de la structure chimique du plastifiant.Voir les détails

Mots clés : PVC, Biosourcé, Epoxydation, plastifiants

Thermal and mechanical properties of bio-basedplasticizers mixtures on poly (vinyl chloride)

Boussaha BOUCHOUL, Mohamed Tahar BENANIBA, Valérie MASSARDIER (2017)
Article de journal

The use of mixtures of nontoxic and biodegradable plasticizers coming from natural resources is a good way to replaceconventional phthalates plasticizers. In this study, two secondary plasticizers of epoxidized sunflower oil (ESO)and epoxidized sunflower oil methyl ester (ESOME) were synthesized and have been used with two commerciallyavailable biobased plasticizers; isosorbide diesters (ISB) and acetyl tributyl citrate (ATBC) in order to produce flexiblePVC. Different mixtures of these plasticizers have been introduced in PVC formulations. Thermal, mechanical andmorphological properties have been studied by using discoloration, thermogravimetric analysis (TGA), differentialscanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), tensile - strain and scanning electronmicroscopy (SEM). Studies have shown that PVC plasticization and stabilization were improved by addition ofplasticizers blends containing ISB, ATBC, ESO and ESOME. An increase in the content of ESO or ESOME improvedthermal and mechanical properties, whereas ESOME/ATBC formulations exhibited the best properties.Voir les détails

Mots clés : PVC, epoxidized sunflower oil, epoxidized sunflower oil methyl ester, isosorbide diesters, acetyl tributyl citrate.

Study of the effect burnishing on superficial hardness and hardening of S355JR steel using experimental planning

Mounira Bourebia, abdeljalille bouri, Hamid Hamadache, Sihem ACHOURI, lakheder laouer, amel gherbi, Oualid GHELLOUDJ (2019)
Article de journal

Surface hardness plays an important role in lifetime of a mechanical piece subjected to friction and wear. Indeed, the hardness can be improved by superficial plastic deformation processes (SDP), such as mechanical surface treatment "MST", in particular the ball burnishing. However, the treatment result of is conditioned by mastery of operation thus ensuring treated piece good mechanical and geometric properties. Experimental work was carried out by applying the ball burnishing process on steel tensile specimens S355JR, in order to observe the influence of treatment parameters regime on surface hardness ‘Hv’ and the effect of latter on tensile behavior of this steel. Two parameters of regime were considered namely: burnishing force "Py" and number of passes "i". The relationship between these parameters and microhardness measured at "Hv" surface has been highlighting using factorial plans 22. Moreover a mathematical model has been obtained allowing prediction of response (Hv) as well as optimization of parameters of treatment regime. The experimental results showed that for surface hardness Hv it is possible to reach a 45% improvement rate for a burnishing force py = 20 Kgf and a number of passages i = 3 for this material. Regarding behavior of material during tensile test, for a low burnishing force (py = 10N) and a number of passes (i = 5), the section further weakening (S = 4.14), proof than ductility of material has decreased.Voir les détails

Mots clés : Surface hardness, factorial designs, ball burnishing, Mathematical model, tensile behaviour

ZnO nanoparticles and biocidal effect of nanostructured ZnO filmson Escherichia coli

Nabila Bouasla, Sihem Abderrahmane, Sameh Athmani, Amel Oulabbas, Mohamed Bououdina (2018)
Article de journal

The biocidal effect of ZnO nanostructured films was studied using Escherichia coli ATCC 43897. TheZnO nanoparticles were synthesized in diethylene glycol by using zinc acetate forced hydrolysis.X-ray diffraction analysis confirmed the formation of single wurtzite-type ZnO phase with a crystallitesize of 20.59 nm. Transmission electron microscopy observations revealed spherical-shaped particlesin the nanoscale regime with a mean particle size of 21.96 nm. It was found that the addition oftrioctylphosphine during synthesis favored much improved dispersion of ZnO nanoparticles, withsmaller particle size; that is, 16.28 nm. Meanwhile, ZnO film grown onto glass substrate by spin-coatingrevealed single phase with the formation of aggregates (≈700) having mushroom-like morphologyformed of very fine particles in the nanoscale regime. The as-deposited nanostructured films exhibiteda hydrophilic character. The classical bacteriological and electrochemical impedance spectroscopymeasurements enabled the biocidal effect of ZnO nanostructured films with 94% inactivation efficiencyafter 90 min of contact time.Voir les détails

Mots clés : ZnO; Spin-coating; Nanostructured film; Biocide effect; E. coli; EIS

Endurance and Damage in Fatigue of Symmetrical Configuration 2P-2V-2P Perlon-Glass-Acrylic Composite Laminates of Orthopaedic Use

Bachir Redjel, Sihem ACHOURI (2019)
Article de journal

In this paper, an experimental characterization of fatigue behaviour on prismatic specimens of a symmetrical laminated composite material perlon- glass- acrylique 2P-2V-2P for orthopaedic use is conducted. Cyclic repeated solicitation is employed corresponding to applied minimum stress σmin equal zero. The various loading levels imposed on the specimens are 80%, 70%, 60%, 55%, 45%, 35% and 25% of the value of the static failure strength measured in flexure. A significant scatter characterizes the results of material fatigue lifetime. That is the consequence of the heterogeneity of the material structure. The scattered phenomenon prevents any prediction of the lifetime with a good probability using Wohler equation. This enables defining a constant degradation rate by 10% cycle decade. The microstructure morphology study through microscopic observations is also discussed and analyzed. The damage state in fatigue is characterized by a combination of density and orientation of micro-cracks. This damage is mainly due to mechanisms complexity of matrix micro-cracking, inter facial exfoliation, debonding and delamination. The damage evolution stages in the case of cyclic loading have the same nature than those found in static loading but have different chronology and scaleVoir les détails

Mots clés : perlon, acrylic, Orthopaedic, fatigue, Scatter

Natural extract of Opuntia ficus indica as green inhibitor for corrosion ofXC52 steel in 1M H3PO4

Amel Oulabbas, Abd errahmane Sihem (2019)
Article de journal

The purpose of this study is to evaluate the anti-corrosive effect of natural extract of Opuntia Ficus Indica (O.F.I) for XC52steel in 1M H3PO4. Experimental work has been achieved by weight loss, potentiodynamic polarization and EISmeasurement, as well as SEM surface characterization. Among the results obtained, we can mention an inhibitory efficiencyof 90% by gravimetric method and 83.9% by electrochemical method at 10% (v/v) of O.F.I. Moreover, The O.F.I extract actsas a mixed inhibitor; however, adsorption free enthalpy indicates a physisorption. The adsorption obeys the Langmuirisotherm model. These results have been improved by SEM micrographsVoir les détails

Mots clés : corrosion, Opuntia ficus indica, EIS, green inhibitor, XC52 steel