ACHOUR Dakhouche

Beddar Madjeda , Ketfi Sara

Analyse des métaux lourds par absorption atomique et les méthodes électrochimique impulsionnelles

Bakour Zoulikha

Relation entre les propriétés mécaniques, résistance à la corrosion et la microstructure des alliages de Pb de l'accumulateur au plomb

Benkouider Imen

Elaboration et caractérisation des couches minces nanostructurées à base de ZnO pour usage photovoltaïque.

Mahdi allam

Synthèse et caractérisation de matériaux d’électrode à base de nickel à effet électro-catalytique dans la production de l’hydrogène par voie électrochimique

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The evolutions of microstructure and texture and the corrosion behaviour of low light rare-earth containing Mg-1.4Nd and low heavy rare-earth containing Mg-0.6Gd and Mg-0.4Dy (wt.%) were evaluated and compared after processing by high-pressure torsion (HPT) and isochronal annealing at 250 and 450 °C for 1 h using electron backscatter diffraction (EBSD) and electrochemical tests in a 3.5% (wt.%) NaCl solution. The EBSD results show that dynamic recrystallisation (DRX) was restricted in the Mg-1.4Nd alloy which led to a heterogenous deformation microstructure whereas the Mg-0.6Gd and Mg-0.4Dy alloys exhibited a homogenous deformation microstructure formed mostly of equiaxed dynamically recrystallised DRX grains. The HPT processing caused the development of a deviated basal texture in the three alloys. A good thermal stability of the three alloys was noticed after annealing at 250 °C. By contrast, annealing at 450 °C led to a homogenous equiaxed microstructure and weakening of texture for the Mg-1.4Nd alloy and a heterogenous bimodal microstructure with a stable basal texture for the Mg-0.6Gd and Mg-0.4Dy alloys. The HPT-processed Mg–RE alloys exhibited an improved corrosion resistance due to grain refinement. Thereafter, the corrosion resistance of the Mg-0.6Gd and Mg-0.4Dy alloys decreased with increasing annealing temperature due to an increase in grain size while the corrosion resistance of the Mg-1.4Nd alloy was improved after annealing at 450 °C due to precipitation and texture weakening.

Citation

Hiba AZZEDDINE , Achour Dakhouche , A. Hanna, T. Baudin, F. Brisset, Y. Huang, T.G. Langdon, , (2023-01-01), Evaluation of Thermal Stability and Its Effect on the Corrosion Behaviour of Mg-RE Alloys Processed by High-Pressure Torsion, Crystals, Vol:13, Issue:4, pages:662, MDPI

Hydroxyapatite (HA) is a biocompatible and bioactive material used as bone-substitute materials in both orthopedics and dentistry. This work is devoted to studying the synthesis of hydroxyapatite (HA) by sol–gel route using triethyl phosphate (TEP) and calcium nitrate tetrahydrate as calcium and phosphor precursors. In order to optimize the hydrolysis of TEP, each prepared solution was aged in a closed Teflon ® container. Several factors were tested in order to improve the synthesis conditions of well-crystallized HA. The effect of aging time (4 h, 16 h, and 24 h), aging temperature (25 °C, 50 °C, 70 °C, and 90 °C) of the prepared solutions, and the type of solvents (ethanol and/or distilled water) were tested. All dried gels were calcined at 700 °C for 1 h. The obtained results showed that the crystallinity degree of hydroxyapatite increases with aging time and temperature, which must not exceed 70 °C. When the prepared solutions were aged at 90 °C, the tri-calcium phosphate (TCP) was formed as a major phase and HA was present as a very minor phase. It was remarked that the aging of sols in a closed Teflon container ® leads to an important decrease of the aging time and temperature. It was found that 24 h and 70 °C are the optimal conditions for the synthesis of well-crystallized HA. Also, it was deduced that a sufficient amount of water was needed to hydrolyze the triethyl phosphate and consequently, to obtain a well-crystallized HA.

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Fatima Zohra MEZAHI , malika MERZOUGUI , Achour Dakhouche , Foudil SAHNOUNE , DJELEL Kherifi , , (2022), Improvement of the reactivity of triethyl phosphate and structural behavior of hydroxyapatite versus the synthesis conditions by sol-gel route, Chemical Papers, Vol:76, Issue:2, pages:1045-1061, springer

The microstructure and texture evolution of an AZ31 alloy were investigated after hot rolling and subsequent annealing using electron backscatter diffraction (EBSD). First, the alloy was hot-rolled at 350 ◦C up to low, medium and high strain (20, 50 and 85% of thickness reduction, respectively). The alloy samples where then annealed at 350 ◦C for 2, 10 and 60 min. The effect of strain level and annealing on corrosion behavior in seawater was also evaluated using electrochemical tests. At low strain, the microstructure was characterised by the absence of twinning, mainly due to the prior thermo-mechanical history of the as-received alloy. However, various modes of twinning were observed at medium strain. At high strain, the dynamic recrystallization process resulted in a microstructure with a typical basal texture. The results demonstrate that twins are responsible for the deviation of {0002} basal poles from normal towards the transversal direction. Annealing at 350 ◦C for up to 60 min led to normal grain growth in all the samples. In medium and highly strained samples, the deformation texture was retained, while the low strain sample underwent noticeable changes due to the absence of dynamic recrystallization. A synergetic effect of grain refinement and texture weakening was responsible for the alloy’s enhanced corrosion resistance.

Citation

Hiba AZZEDDINE , Achour Dakhouche , S. Tighiouaret, A. Hanna, L. Rabahi, F. Brisset, A-L. Helbert, T. Baudin, D. Bradai, , (2021-01-01), On the evolution of microstructure, texture and corrosion behavior of a hot-rolled and annealed AZ31 alloy, Materials Chemistry and Physics, Vol:267, Issue:, pages:124598, Elsevier

The corrosion behaviour of as-cast binary Mg–0.3Ce, Mg–1.44Nd, Mg–0.63Gd and Mg–0.41Dy (wt%) alloys was investigated in DMEM + 10% FBS solution using electrochemical and weight loss tests. The results revealed that the alloys with heavy RE elements (Gd and Dy) exhibited the lowest corrosion rate compared to the alloys with light RE elements (Ce and Nd). The cytocompatibility of the Mg–RE alloys was assessed via live/dead straining after 3 and 7 days. The results show that Mg–0.63Gd alloy is a suitable candidate for biomedical applications.

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Hiba AZZEDDINE , Achour Dakhouche , A. Hanna, B. Luthringer-Feyerabend, , (2021-01-01), Corrosion behavior and cytocompatibility of selected binary magnesium-rare earth alloys, Journal of Magnesium and Alloys, Vol:9, Issue:, pages:581-591, Elsevier

The corrosion behaviour of Mg-0.3Ce, Mg-0.41Dy, Mg-0.63Gd, Mg-1.44Nd and Mg-1.43La (wt.%) alloys in 3.5 wt% NaCl solution was investigated using electrochemical tests. The as-cast microstructures of the Mg-RE alloys were characterized by the presence of second phases (MgxCe, Mg41Dy5, Mg12Gd, Mg12Nd, Mg41Nd5, Mg24Nd and Mg12La) with different volume fraction and distribution. Results show that the corrosion mechanism was altered from uniform to localized corrosion mechanism depending on the specific RE alloying elements. The corrosion resistance of the Mg-RE alloys is increasing in the following order: Mg-1.43La, Mg-1.44Nd, Mg-0.3Ce, Mg-0.63Gd and Mg-0.41Dy. Accordingly, the corrosion morphology in the best resistant Mg-0.41Dy alloy and the worst Mg-1.43La alloy were observed and compared after 2h and 24 h of immersion using SEM-EDS, XPS and XRD analysis. The formation of the Dy2O3 oxide prevents the Mg-0.41Dy alloy from pitting corrosion and lead to an excellent corrosion surface even after 24 h of immersion. Meanwhile, the presence of a high fraction of the Mg12La phase along the grains boundaries in the Mg-1.43La alloy causes severe pitting corrosion by acting as anodic phase.

Citation

Hiba AZZEDDINE , Achour Dakhouche , A. Hanna, L. Rabahi, N. Scharnagl, M. Dopita, F. Brisset, A.L. Helbert, T. Baudin, , (2020-01-11), Impact of rare-earth elements on the corrosion performance of binary magnesium alloys, Journal of Alloys and Compounds, Vol:829, Issue:, pages:154569, Elsevier

The aim of the present study is to investigate the effect of deformation conditions on the corrosion behavior of AZ31 (Mg-3Al-1Zn, % wt.) in 0.9% NaCl (wt.%) solution. The AZ31 alloy was hot rolled at 360 °C to 20 and 50% of thickness reduction. Electrochemical measurements were used to study the corrosion behavior of AZ31 alloy. Analysis of corrosion products after immersion test was performed using optical microscopy, X-ray diffraction and Raman spectroscopy. The mechanical properties of corroded samples were investigated using tensile test at room temperature. Results indicated that the corrosion rate was strongly affected by the hot rolling level. A lower corrosion potential and reduced polarization resistance was observed after hot rolling compared to the as received AZ31 alloy. The corrosion product was evidenced mainly as Mg(OH)2 compound exhibiting a filiform-like morphology. Apparently, the corrosion improved the room temperature ductility of AZ31 alloy.

Citation

abdelkader hanna , Achour Dakhouche , Hiba AZZEDDINE , K. Tirsatine, A. Sari, Y. Khereddine, D. Bradai, , (2019), Effect of hot rolling on the corrosion behavior of AZ31 magnesium alloy, Metallurgical Research & Technology, Vol:116, Issue:, pages:109, EDP Sciences

samples in the 0.5 M H2SO4 solution at 25 C. Electrochemical impedance spectroscopy (EIS) diagrams, potentiodynamic polarization curves and the equivalent circuit analysis were used to evaluate the electrochemical corrosion response. It was found that Pb-1 wt.% Sn alloy exhibits a microstructure with large cellular array and better electrochemical corrosion resistance than that of Pb-1 wt.% Sb.

Citation

Achour Dakhouche , , (2018), Electrochemical Corrosion of Pb-Sn and Pb-Sb Alloys for Lead-Acid Battery Applications, ACTA PHYSICA POLONICA A, Vol:134, Issue:1, pages:103-106, online

The effect of three tetrahydroxylated Schiff bases as N,N-bis(2,3-dihydroxybenzyl- idene)-4,4’-diphenylmethane, N,N-bis(2,4-dihydroxybenzyl- idene)-4,4’-diphenylmethane and N,N-bis(2,4-dihydroxybenzylidene)-4,4’-diphenylmethane were studied as inhibitors for mild steel in 1M HCl medium. The experiments were performed using potentiodynamic polarization. This inhibition proved an efficient increase according the position of second hydroxyl of salicylaldehyde suggesting that this inhibition is dependent on concentration and the compound nature. Among these position-isomers, the best inhibition efficiency was obtained with p-hydroxylated (94%) at 1mM. Tafel plots of these inhibitors are the mixed- type, their adsorption is spontaneous obeying to Langmuir’s isotherm. AFM/SEM-EDS characterized metal surface. DFT-calculations and molecular dynamics simulations are correlated to inhibition efficiency obtained.

Citation

Achour Dakhouche , , (2018), ELECTROCHEMICAL AND THEORETICAL STUDIES INFLUENCING THE EFFECT OF HYDROXYL POSITION OF TETRAPHENOLIC SCHIFF BASES TOWARDS CORROSION INHIBITION OF MILD STEEL IN 1M HCl, Journal of Fundamental and Applied Sciences, Vol:10, Issue:3, pages:209, Online

Pb–Sn, Pb–Sb and Pb–Ca–Sn alloys are commonly used in the production of positive and negative grids, of both valve-regulated lead–acid (VRLA) and Starting, Lighting and Ignition (SLI) batteries.Pb-Sn binary alloys with different contents of tin (0–2 wt.%) were investigated as the positive grid of a lead acid battery. The microstructure of Pb–Sn alloys was observed using a polarizing microscope. The electrochemical properties of Pb–Sn alloys in sulfuric acid solution were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweeping voltammetry (LSV). The results indicate that the introduction of tin results in grain large and augmented corrosion resistance.

Citation

Achour Dakhouche , bakhour Zoulikha, ,(2018), Effect of tin on the corrosion résistance of Pb-Sn alloys in H2SO4 solution.,International symposium on materials chemistry,Boumerdes

Pb–Sn binary alloys with different contents of tin (0–2wt.%) were investigated as the positive grid of a lead acid battery. The microstructure of Pb–Sn alloys was observed using a polarizing microscope. The morphology of the corrosion layers and corroded surfaces of Pb and Pb–Sn alloy electrodes were analyzed by scanning electron microscopy (SEM) following the corrosion test. The electrochemical properties of Pb–Sn alloys in sulfuric acid solution were investigated by cyclic voltammetry (CV), open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and linear sweeping voltammetry (LSV). The results indicate that the introduction of tin results in grain refinement, increased corrosion resistance.

Citation

Achour Dakhouche , Bakour Zoulikha, ,(2018), Study on the structure and property of Lead tin alloy as the positive gride.,The first International Conference on Electrochemical Science and Technology,Sétif

It well known that PbSb alloy has high performance on the charge–discharge for the lead-acid battery. While the demerit of PbSb alloys is that they can increase the water loss in lead acid battery by decreasing the over-potential of hydrogen evolution on the negative plate, andself-discharge of battery and further to the premature loss of the battery capacity. The over-potential of hydrogen evolution on PbCa alloy is higher than that on PbSb alloy for about 200 mV, which result in its lower rate of water consumption and a smaller rate of self-discharge, and then make the PbCa alloy more suitable for maintenance-free applications or valve regulated lead acid battery (VRLA). However, PbCa alloy has an unfavourable factor usually referred to as premature capacity loss (PCL), which is attributed to an high impedance barrier layer composed of PbO, and formed easily at the interface of the positive grid and the active material, which has an undesirable effect of increasing the anode impedance after storage for a certain period of time, and then the capacity of lead acid battery decreasing sharply. In order to improve the conductivity of the passive layer and the charge–discharge performance of the batteries, Sn should be added into the PbCa alloys. According to Giess et al., Sn suppresses the transformation of lead to α-PbO , and inhibits the growth of Pb(II) compound in the film. Although, the passive phenomena of the film cannot be thoroughly eliminated by adding Sn, and excessive Sn content may increase the self- discharge of the lead acid battery but how to promote the maintenance-free property of the battery is still a key problem for developing the novel grid alloy. I well known that during the anodic polarization of a lead electrode dipped in a H2SO4 solution in the lead oxide potential region (-0.40 to + 0.95 V vs. a Hg/Hg2SO4 reference electrode) the electrode system Pb/PbO layer/Pb2SO4 membrane/H2SO4 solution is formed. It was determined by X-ray diffraction that mainly the tetragonal PbO is formed, as well as small amounts of orthorhombic PbO and basic lead sulphates. It was established that the Pb/PbO/Pb2SO4/H2SO4 electrode is photoactive in the visible band (up to 650 nm) of the spectrum. So, the photoeffect is related to the semiconducting properties of the lead monoxide layer (PbO) formed on lead. In this work, the corrosion layer formed in dark on pure Pb and Pb-Sn alloys was photo electrochemically studied using: AC voltammetry, Cyclic voltammetry CV, Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky plots and Photocurrent measurements. The composition was determined by XRD analysis. It was found that tin reduces the thickness and enhances the conductivity of the corrosion layer by formation of conductive and no photoactive tin oxides. A mechanism of action of tin was proposed

Citation

Achour Dakhouche , Dilmi toufik, ,(2018), Photoelectrochemical study of PbO doped with Sn.,International Conference on Materials Science (ICMS2018),,Boumerdes

Magnesium and its alloys are increasingly used as lightweight materials in aerospace, automotive and as biomaterials owing to their lower density among all structural materials (ρMg = 1.73 g cm-3). However, Magnesium alloys suffer from poor workability and relative low mechanical strength at ambient temperature due to their hexagonal close packed structure and the associated lack of sufficient independent slip systems which limit their applications as structural materials. Furthermore, their poor corrosion resistance is a serious problem that limits their clinical application. In fact, the control and improvement of mechanical properties of magnesium alloys could be obtained through thermo-mechanical processing such as hot rolling or hot compression. The aim of the present study is to investigate the effect of hot deformation conditions on the corrosion behavior of AZ31 (Mg-3Al-1Zn, % wt.) in 0.9% NaCl solution. The AZ31 alloy was hot rolled at 360 °C to 20 and 50 % of thickness reduction. Electrochimical techniques such as open circuit potential, polarization curves and electrochimical impedance spectroscopy complemented by X-ray diffraction were used. Primary results show that the corrosion rate was strongly affected by the hot rolling level. A lower potential and reduced polarization resistance were observed after hot rolling compared to the as cast AZ31 alloy. Besides the two capacitive loops, all samples exhibited an inductive loop that decreases with increasing thickness reduction which can be associated with the development of more uniform corrosion.

Citation

Achour Dakhouche , ,(2018), Effect of hot rolling on the corrosion behavior of AZ31 magnesium alloy,International symposium on materials chemistry,Bouberdes

at room temperature was studied in an effort to evaluate the effect of applied potential on the composition limits, corrosion resistance and the electrocatalytic properties of the deposits towards the hydrogen evolution reaction (HER) in concentrated alkaline solution. The alloys were potentiostatically electrodeposited onto pure copper sheet substrates. The electrodeposits were characterized by means of field-emission scanning microscopy (FESEM) and energy dispersive X-ray analysis (EDXA). In an electrolyte where MoO2
4 =WO2
4 ¼ 1 : 1, at a given deposition potential, there is more Mo than W in the deposits, indicating an advantageous induced co-deposition of Mo compared to W. The nucleation mechanism, studied according to Scharifker-Hills theoretical model, revealed an instantaneous nucleation followed by a three-dimensional growth. On the hand, increasing MoO2
4 =WO2
4 ratio in the electrolyte under the same deposition potential reduced both Ni and W content in the deposits. A different trend was observed in an equimolar solution, when applying more negative potentials, both Mo and W contents decreased leading to the enhancement of Ni amount. The stability in corrosive media and the catalytic performances of the coatings depended mainly on the applied overpotentials, A mechanism of induced co-deposition of molybdenum and tungsten with nickel is proposed and discussed.

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Achour Dakhouche , Mahdi Allam, Mohamed Benaicha, , (2017), Electrodeposition and characterization of NiMoW alloy as electrode material for hydrogen evolution in alkaline water electrolysis, i n t e r n a t i o n a l journal of hydrogen energy, Vol:10, Issue:10, pages:105, Elsevier

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Achour Dakhouche , ,(2017), Electrochemical corrosion of Pb-Sn and Pb-Sb alloys for lead-acid battery applications,7th APMAS ‘’International Advance in Apllied Physics and Materials Science Congress & Exhibition,Sentido Lykia Resort Oludeniz, Turkey

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Achour Dakhouche , ,(2017), Study of the growth process of corrosion layer obtained by cycling on Pb/Sn alloy.,3rd International Symposium on Materials and Sustainable Development ISMS,Boumerdes - Algeria

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Achour Dakhouche , Bakour Zoulikha, ,(2017), Microstructure and electrochemical corrosion behavior of Pb- wt % Sn alloy for lead-acid battery,First arab conference on mechanical engineering,Biskra

The electrodeposition of NiW alloys from citrate electrolyte was studied in an effort to evaluate the effect of applied potential and solution pH on the composition limit and the properties of the deposits. Electrochemical measurements employing cyclic voltammetry (CV), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to investigate the codeposition process, corrosion resistance and HER electrocatalytic properties of the deposits. The deposits morphology was characterized by scanning electron microscopy (SEM) and the surface composition of coatings was ascertained by Energy dispersive x-ray analysis (EDXA). Possibility of W-rich NiW alloys electrodeposition from ammonia-free citrate electrolyte at room temperature was confirmed. The tungsten content was close to 32 at.% in deposits obtained from a quasi-neutral solution. Structural study revealed that all of NiW coated alloys were amorphous regardless of W content. On the other hand, it was found that Ni-W alloys deposited at -1.4 V/CSE (having about 14 at.% W) are good electrode materials as cathode for HER following the Volmer-Heyrovsky mechanism with substantial surface-adsorbed hydrogen while alloys plated at -1.2 V/SCE (having about 32 wt.% W) were of excellent corrosion resistance in 3.5% NaCl solution.

Citation

Achour Dakhouche , Mohamed Benaicha, Mahdi Allam, Meriem Hamla, , (2016), Electrodeposition and Characterization of W-rich NiW Alloys from Citrate Electrolyte, International Journal of ELECTROCHEMICAL SCIENCE, Vol:11, Issue:1, pages:7605 – 7620, Online