Publications Scientifiques

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    Effect of alloying additions and high temperature t5-treatment on the microstructural behavior of al–si-based eutectic and hypo-eutectic alloys
    (Springer, 2021) Sersour, Zakia; Amirouche, Lynda
    The present study has been undertaken to investigate the effect of alloying additions and high temperature T5-treatment consisting of high temperature direct aging after casting, on the microstructural characteristics of some Al-Si-based eutectic and near-eutectic alloys, typically used in the automotive industry. For comparison purposes and in order to estimate the effect of Mg, three sets of samples consisting of Al-11.9wt%Si (AS13, B413), Al-11.67wt%Si-0.22wt%Mg (AS10G) and Al-7.2wt%Si-0.44wt% Mg (AS7G06, A356) alloys have been first studied in the as-cast state. In order to examine the effect of heat treatments, three groups of alloys were investigated in two different states, namely: (i) after T6-treatment consisting of solutionizing at 540 °C for 10 hours, water quenching and then aging at 160 °C for 4 hours; and (ii) after high temperature T5-treatment consisting of annealing at 300 °C, 450 °C and 500 °C for different aging times in order to locate a possible peak hardness. Microstructural examination was carried out using optical microscopy, scanning electron microscopy, energy Dispersive Spectrometry (EDS), X-Ray Diffraction and Brinell-hardness measurements. Our as-cast alloys’ microstructure revealed that all the different intermetallic phases, such as the Q-Al5Cu2Mg8Si6 phase, the α-Al15(MnFe)3Si2, β-Al5-Fe-Si, π-Al8FeMg3Si6 and Al7Cu2Fe iron-rich compounds, as well as the Al2Cu and Mg2Si hardening precipitates, have been formed during solidification. Besides, X-rays diffraction patterns revealed that while some Al2Cu hardening precipitates have exhibited total dissolution, after solutionizing, the undesirable iron-rich phases have remained at least partially insoluble after the different heat treatments. A semi-quantitative X-Rays diffraction analysis, performed after the different heat treatments, has shed light on the interplay between the Fe-rich intermetallic compounds, denoting the transformation of the π-Al8FeMg3Si6 into the β-Al5FeSi phase on the one hand and between π-Al8FeMg3Si6 and Q-Al5Cu2Mg8Si6 phases in the precipitation and dissolution of Al2Cu and Mg2Si phases on the other hand. Both of the two processes, marking a certain interaction between the different intermetallic compounds, are observed to give rise to a significant release of Mg and Si solute atoms and to enhance the hardening precipitates volume fraction after heat treatments. It turns out that high temperature T5-treatment is more appropriate and even more efficient than the usual T6 one, in the sense that it yields a more significant amount of hardening precipitates giving rise to higher hardness peaks with just one step treatment.
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    Mechanical and damage properties of polyethylene reinforced with clay treatment
    (Technology Publishing Group, 2021) Chebbab, Brahim; Djeziri, M.; Bezzazi, B.
    This document is the subject of an experimental study for composite material implementation with a polyethylene matrix (HDPE) embedded with clay particles. We carried out a chemical optimization applied to clay particles by characterizing the mechanical behavior as well as the damage of the elaborated composite material. The work is based on the following optimized procedure: a mixture of sodium thiosulfate (Na2S2O3) and clay cooled and centrifuged for 15 minutes. The clay pellet is rinsed twice with 0.05 M HCl for 3 to 4 hours. The mechanical properties of the composite material obtained are relative to the mass fraction of treated and untreated clay. The Young's modulus is found to change as the mass loadings of the injected treated clay change, with a marked improvement over virgin HDPE from 1590.90 to 1667.32 MPa, the yield strength from 28.68 to 31.73 MPa, and the ultimate tensile strength from 19.99 to 20.84 MPa. This positive variation is achieved at a maximum of 7% mass load of treated clay. Beyond this rate, the composite material experiences a drop in these same parameters due to the high concentration of clay. Scanning electron microscopy is used to see differences in dense microstructure between specimen granules
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    Experimental and theoretical evaluation of the adsorption process of some polyphenols and their corrosion inhibitory properties on mild steel in acidic media
    (Elsevier, 2021) Zerroug, Meriem; Ferkous, Hana; Djellali, Souad; Bouzid, Abderrazak; Mohammed A., Amin; Rezki, Leila; Belakhdar, Amina; Jeon, Byong-Hun; Boulechfar, Chérifa; Benguerba, Yacine
    Polyphenols are now widely acknowledged as safe and biodegradable corrosion inhibitors due to their cost-effectiveness. As a result, this research examines how well polyphenols extracted from Artemisia Herba alba (AHA) prevent mild steel corrosion in a 1 M HCl solution. Inhibitory performance is determined using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and weight loss tests. The shape and chemical content of the mild steel sample surface are evaluated by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) after contact with AHA secondary metabolites in the acidic solution. According to the results of polarization curves, AHA extract works as a mixed-type inhibitor. For all AHA concentrations tested, the Nyquist plots show a semi-circular capacitive loop. On metal surfaces, the Langmuir isotherm regulates inhibitor adsorption. The effectiveness of inhibition is proportional to the extract concentration, reaching 92.9% at 900 ppm. On metal surfaces, the Langmuir isotherm governs inhibitor adsorption. The effectiveness of inhibition is proportional to the extract concentration, reaching 92.9% at 900 ppm. These findings are supported by metal surface experiments, which show that the deposited inhibitor molecules successfully prevent HCl attacks at steel grain boundaries. Finally, quantum chemistry simulations show that dicaffeoylquinic acids, which were found to be the most prevalent AHA extract components, are effective corrosion inhibitors
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    Hybrid Cements From Metakaolin, Slag And Clinker Mixtures. Influence Of Activators
    (Université M'hamed Bougara de Boumerdès, 2013) Zibouche, Fatima; Ferna´ndez- Jime´nez, A.; Boudissa, N.; Palomo, A.; Abadlia, Mohamed Tahar
    Hybrid cements containing a mixture of aluminates gels-substituted CSH (CASH) and NASH phases and other phases are investigated. The mechanical strength and structures of hybrid cement with geopolymeric matrix of aluminosilicates and clinker are examined. These geopolymeric matrixes are based on polycondensation of the powder precursors by alkaline activation. The activators can be solids (alkalis of sulfates and carbonates,) or liquid (alkaline solutions of silicates). The type of alkaline cation (Na, K) influences the activation. The phase’s transformations are characterised by the following parameters: the effect of cures (2, 7, 28 days) and their impact on the hardening, the texture and the mechanical strength. These properties are correlated by complementary techniques of DRX, FTIR, SEM / EDX. Alkaline potassium K more than the sodium Na allows the obtaining of products of denser reactions what increases the strength of cohesion of the matrix and show higher mechanical resistances.
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    Study of Temperature and Concentration Effects for CZTS Layers using Spray Pyrolysis
    (IEEE, 2017) Haouanoh, Djedjiga; TalaIghil, Razika Zaïr; Toubane, Mahdia; Bensouici, Fayçal; Zair, Razika
    In this study, Cu 2 ZnSnS 4 (CZTS) layers were successfully deposited onto glass and silicon substrates by spray pyrolysis technique. The surface morphology, chemical, crystal phase structure and optical properties of (CZTS) thin films were characterized using a scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffractometer (XRD) and UV-visible spectrophotometer. Substrate temperatures and concentrations of precursor effects parameters were investigated. X-ray diffraction showed the formation of kesterite phase. SEM images revealed uniform, smooth, porous, and compact and densely packed morphology. A wide variation in the value of the band gap is observed when we have changed both parameters temperature and concentration.
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    Study of the influence of Na/Li on the microstructure of an aluminosilicate nuclear glass
    (2018) Moudir, Dalila; kamel, Nour El Hayet; Benmounah, Abdelbaki; Ikhaddalene, Soumia; Mouheb, Yasmina; Aouchiche, Fairouz
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    Effect of surfactants on the electrochemical behavior of the positive plate
    (2016) Boudieb, Naima; Bounoughaz, M.; Bouklachi, A.
    The main goal of this research is to improve the performance of positive plate of lead-acid battery using surfactants in 0.5 M H 2 SO . The use of surfactants aims to increase the ability and the cycle life of the positive active material. The electrochemical behavior of pure lead and PbO 4 electrodes interface was investigated at room temperature by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potential-dynamic polarization curves. Scanning electron microscopy (SEM) was used to explore the film layer morphology deposited on the surface of working electrodes. Cyclic voltammograms of pure lead (Pb) electrode show that in the presence of PS the current peaks of the transition of PbO 2 to PbSO 4 and PbO 2 to PbSO 4 2 dropped at small concentrations of surfactants. We observed a remarkable improvement of the discharge capacity of the PAM for an amount of PS ranging between 10 and 50 ppm. EIS results indicate the improvement of mass transport by the decrease of resistance. In the other hand, the PbSO 4 surface layers and the crystal size of PbSO changes with impact effect of surfactants. As a result of the morphological changes which occurred, the PbO 4 films formed are hardly more reducible with PbSO 4 and delays the appearance of resistive PbSO layers at the material interface. As a conclusion, we can say that the electrical performance of the battery increase by extending the life cycle
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    Effect of the iron concentration on the properties of an aluminosilicate glass used for storage of radioactive waste
    (PARLAR SCIENTIFIC PUBLICATIONS (PSP), 2016) Moudir, D.; Ikhaddalene, Soumia; Kamel, N.; Benmounah, A.; Zibouche, Fatima; Mouheb, Y.; Aouchiche, F.
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    Structural, optical and photocatalytic properties of ZnO nanorods : effect of aging time and number of layers
    (Elsevier, 2016) Toubane, Mahdia; Tala-Ighil, Razika; Bensouici, F.
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    The effect of surfactants on the efficiency of lead acid batteries
    (Elsevier, 2015) Boudieb, Naima; Bounoughaz, M.; Bouklachi, A.
    The aim of this study is to show the effect of two phosphonate surfactants (PS) on the electrochemical behavior of the negative plate of lead-acid battery in the sulfuric acid medium. The characterization of the electrode interface was investigated at room temperature by a set of electrochemical techniques as linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). Scanning electron microscopy (SEM) was employed to determine the film layer's morphology deposited on the surface of working electrodes, in the presence and in the absence of the PS. When the PS was added in the acidic solution, hydrogen evolution became higher, the over-potential of hydrogen was shifted to negatives values and the growth of the anodic β-PbO2 was inhibited. SEM imaging with the presence of PS showed reduction in the growth of the anodic β-PbO2 and PbSO4 layers. EIS results indicate the decrease of the conductivity of β-PbO2 film on the lead surface electrode. The result of the CV, show a decrease in the peak related to transition of PbO to Pb demonstrates that lower PbO has been formed underneath the lead sulfate membrane in the presence of low concentration of SP indeed a decrease in the amount of formed PbSO4 on the electrode surface