Sciences des matériaux

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Etude de l’influence du traitement thermique sur les propriétés mécaniques et électrochimiques d’un rechargement E-309L / 316L-17 sur l’acier 25CrMo4

A.DJELAMA, A.A.LECHEA  (2022)
Mémoire de Master

The main concerns of industrialists having a relationship with the field of oil drilling is wear and corrosion a set of phenomena that act alone or in combination. We propose through this work in addition to the fact of making bi-materials by the hard reloading process to the MMA coated electrode (Manuel Métal arc), using the electrode E309L-17 in the first pass and 316L-17 in finish on low alloy chromium nickel 25CrMo4 steel, This type of steel is used during maintenance on borehole head preventers. In this welding configuration, see quality on the weld by discussing the effect of the chosen parameters on the cohesion at the substrate-input metal and the optimization of the welding process. Three essential steps to be considered in this study: the production of bi-materials by MMA reloading, microstructural, mechanical characterization of compounds and the electrochemical study in NaCl has 3.5% Voir les détails

Mots clés : 25CrMo4, Interface, reloading, corrosion, tribology, heat treatmen

Étude de l’influence du traitement thermique sur les propriétés mécanique du rechargement ENiCrMo-3 sur l’acier 25CrMo4

A. LALOUI, A. ANIK  (2022)
Mémoire de Master

L’usure est la préoccupation des industriels ayant une relation avec le domaine du forage pétrolier, un ensemble de phénomènes faisant intervenir une détérioration progressive par frottement, érosion qui agissent seuls ou en combinaison. Nous nous proposons, à travers ce travail de réaliser un bi-matériaux par le procédé de rechargement dur, à l’électrode enrobé MMA (Manuel Métal arc), sur l’acier faiblement allié au chrome-nickel 25CrMo4, en utilisant l’électrode ENiCrMo-3. Ce type d’acier est utilisé lors de la maintenance sur les obturateurs de tête de puits de forage. Dans cette configuration de rechargement, voir la qualité du rechargement en discutant l’effet des paramètre choisis sur la cohésion à l’interface substrat-métal d’apport utilisant la technique de corrélation d’image et voir l’effet du traitement thermique par l’approche tribologique sur la partie supérieure du rechargement. Trois étapes essentielles sont à envisager dans cette étude : La réalisation par rechargement MMA, la caractérisation microstructurale et mécanique du composé. Voir les détails

Mots clés : 25CrMo4, Interface, MMA, rechargement, corrélation d’image, fatigue.

Synthesis, Characterization, and Photocatalytic Activity ofBa-Doped BiFeO3 Thin Films.

KHIAT Abdelmadjid, Felicia Gheorghiu Boughelout Abderrahmane.  (2022)
Publication

Abstract: In the present paper, Bi1-xBaxFeO3 (BBFO) thin films (where x = 0, 0.02 and 0.05) wereprepared by a combined sol-gel and spin-coating method. The influence of Ba substitutions on thestructural, microstructural, optical properties, and photocatalytic activity of BiFeO3 thin films hasbeen studied. X-ray diffraction pattern correlated with FTIR analysis results confirms that all thefilms have a perovskite structure of rhombohedral symmetry with an R3m space group. Atomicforce microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate thesurface morphology and reveals microstructural modifications with the increase in Ba concentration.The optical properties show that the band gap is narrowed after doping with Ba ions and decreasesgradually with the increase of doping content. The photocatalytic investigations of depositedfilms revealed that Ba doping of BFO material leads to the enhancement of photocatalytic response.The present data demonstrates that Bi1-xBaxFeO3 (BBFO) thin films can be used in photocatalyticapplications. Voir les détails

Mots clés : perovskites; films; optical properties; doped BaTiO3; photocatalytic activity

Synthesis and characterization of hydroxyapatite powder derived of eggshell by precipitation method

Samira TLILI, Saida Bouyegh, kotbia LABIOD, Noura Traiaia, Mohamed Hassani, Bilal Ariche  (2022)
Publication

Hydroxyapatite is the inorganic material with formula Ca10(PO4)6(OH)2. It is one of bioceramic was used for one repairs, fixing defects of filing voids in biomedical fields. The use of chicken eggshell is one of the natural sources to obtain the calcium phosphate compounds. The main objective of this study is to synthesize the hydroxyapatite by precipitation method from eggshell. The raw eggshell was calcined at 850°C for 2 hours following by grinding for 16 hours. The HA powder was synthesized by wet chemical method, using eggshells and phosphoric acid (H3PO4). X-ray diffraction spectroscopy (XRD, Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) were used to characterize the morphology, composition and distribution of the particles. The Thermos gravimetric analysis (TGA-DTA) was also carried out to evaluate the stability of the synthesized HA powder. The particle-size distribution (PSD) of the powder was determined by the laser scattering particle size distribution analyzer. The results showed that the sintered at 1000°C of HA powder resembles the feature of pure and single apatite phase having favorable Ca/P ratio. Voir les détails

Mots clés : hydroxyapatite, Bioceramics, synthesis, Eggshell, Precipitation.

A systematic DFT study of (Ti3/2RE1/2)AlC alloys: A new database foradjustable mechanical and electronic properties

C. Meftah, N. Iles, L. Rabahi, M. Gallouze, H.I. Feraoun, M. Drir  (2022)
Publication

In this study, ab initio calculations based on Pseudo-Potential Density Functional Theory (PP-DFT) method arecarried out in order to highlight the partial substitution effect of Rare Earth (RE) elements in the well-known 211-MAX phase of Ti2AlC. The considered elements are Y, Sc and RE = La, Ce, Pr, Nd, Sm, Eu, Gd leading to (Ti3/2RE1/2)AlC alloys. According to the obtained results, the (Ti3/2RE1/2)AlC alloys are significantly less compressibleunder uniaxial stress along x and z axes. They exhibit high resistance to shearing along <001> direction. Inaddition, the calculated heat capacity for (Ti3/2RE1/2)AlC alloys increases with respect to the temperature, amaximum is found in the temperature range 200–300 K. Localized states occur in (Ti3/2RE1/2)AlC alloys due tothe f states filling of the rare earth elements. The magnetic moment of (Ti3/2RE1/2)AlC compounds increasesaccording to 4f n (n=2 for Ce to n=7 for Gd) filling. Our findings provide a theoretical database for new tunableproperties of (Ti3/2RE1/2)AlC alloys. Voir les détails

Mots clés : DFT, Rare earth elements, (Ti3/2Re1/2)AlC, mechanical properties, Localized States, Magnetic moment

Preparation and characteristics of synthesized hydroxyapatite from bovine bones and by co-precipitation method

Saida Bouyegh, Samira TLILI, kotbia LABIOD, Mohamed Hassani, Mohamed Grimet, Oussama Bensalem  (2022)
Publication

Hydroxyapatite (HA, (Ca10(PO4)6(OH)2) is a widely studied bioceramic due to its biocompatibility, bioactivity, and chemical similarity to the mineral component of bone. Generally, hydroxyapatite can be made from several natural and synthetic sources. The objective of this study is to prepare hydroxyapatite powders from different precursors (natural or chemical). Hydroxyapatite was synthetized by co-precipitation method, the chemical precursors of which are [Ca(NO3)2.4H2O, (NH4)2HPO4] and the natural source was bovine bone. Bovine hydroxyapatite (BHA) was extracted from the bovine bone bio-waste via thermal method and milling process. Synthesized HA (SHA) was prepared by co-precipitation method with the pH 10.0 of mother liquor. The prepared powders were characterized using various analytical techniques such as XRD, FTIR spectroscopy, thermogravimetry (TG), and scanning electron microscope (SEM). These techniques provide information about the structural, chemical, morphological and physicochemical of each of the prepared powders. The use of co-precipitation method produced a low crystallinity of HA while the thermal method increased crystallinity. On the other hand, the results showed that the Ca / P ratio of synthetic hydroxyapatite (SHA) as well as that of bovine bone source (BHA) was also stoichiometric. Voir les détails

Mots clés : hydroxyapatite, Bovine bone, synthesis, co-precipitation, thermal decomposition.

Tribocorrosion Dependence on Porosity of TiNi Alloysin Phosphate‑Buffered Saline Solution

KAHLOUL Latifa, MEDDAH Soumaya, Nasser Eddine BELIARDOUH, Alex Montagne, Mohamed Bououdina, Said Boudebane  (2022)
Publication

Degradations of implants during their service life lead to rejection because of corrosion and wear-related problems, i.e., toxicions and wear particles released into the human body. In this case, tribocorrosion tests are appropriate ways to investigate thesynergistic effect of the corrosion and wear phenomena, on the material implant in simulated body fluids. This study aims toanalyze the bio-tribology as well as the tribocorrosion performances of porous TiNi alloys, fabricated from elemental powdermixture (Ti, Ni) by powder metallurgy. The effect of the level in porosity, resulting from four (04) different cold pressing, wasinvestigated against alumina ball in phosphate-buffered saline solution (PBS) at 37 °C. SEM/EDS microstructural analysesrevealed the presence of various phases with TiNi as the predominant phase. Obtained results showed that the lowest frictioncoefficient was recorded for the sample with 33% in porosity rate when sliding against an alumina ball in dry conditions. Ahigh tribocorrosion resistance for all the studied TiNi compositions was also observed. Based on the corrosion parametersand the wear rate, the composition with the highest porosity exhibited the optimum performance. Voir les détails

Mots clés : TiNi alloys, Biotribolgy, Tribocorrosion, Porosity

Effet du traitement de vieillissement sur l’évolution microstructurale et le comportement électrochimique des aciers inoxydables 2101, 2205 et 2507.

F.Z.ROUIBI  (2021)
Mémoire de Master

this work, the effect of ageing treatment on the microstructural evolution, morphology and potential distribution of LDX2101, SDX2205 and SDSS 2507 stainless steels is investigated. The heat treatment is carried out in two stages: solution treatment for one hour, then water quenching followed by ageing at 750°C for 2101 and 850°C for 2205 and 2507, for 24 hours holding time. Metallographical characterization is conducted using optical microscopy and scanning electron microscopy (SEM) as well as XRD analysis to identify the phases and precipitates formed after treatment. In order to study the effect of ageing on the morphological changes, magnetic behavior and potential distribution on the surfaces of the treated steels, different modes of atomic force microscopy (AFM) are used. The results showed a clear increase in roughness with a very heterogeneous potential distribution due to microstructural changes as a result of the formation of precipitates and secondary phases Voir les détails

Mots clés : LDX2101, SDX2205, SDSS 2507 stainless steels, The heat treatment

Structural, Magnetic, Dielectric and Piezoelectric Properties of Multiferroic PbTi1−xFexO3−δ Ceramics

Khiat Abd elmadjid, Felicia Gheorghiu, Mokhtar Zerdali, Ina Turcan, Saad Hamzaoui  (2021)
Publication

PbTi1−xFexO3−δ (x = 0, 0.3, 0.5, and 0.7) ceramics were prepared using the classical solid-state reaction method. The investigated system presented properties that were derived from composition, microstructure, and oxygen deficiency. The phase investigations indicated that all of the samples were well crystallized, and the formation of a cubic structure with small traces of impurities was promoted, in addition to a tetragonal structure, as Fe3+ concentration increased. The scanning electron microscopy (SEM) images for PbTi1−xFexO3−δ ceramics revealed microstructures that were inhomogeneous with an intergranular porosity. The dielectric permittivity increased systematically with Fe3+ concentration, increasing up to x = 0.7. A complex impedance analysis revealed the presence of multiple semicircles in the spectra, demonstrating a local electrical inhomogeneity due the different microstructures and amounts of oxygen vacancies distributed within the sample. The increase of the substitution with Fe3+ ions onto Ti4+ sites led to the improvement of the magnetic properties due to the gradual increase in the interactions between Fe3+ ions, which were mediated by the presence of oxygen vacancies. The PbTi1−xFexO3−δ became a multifunctional system with reasonable dielectric, piezoelectric, and magnetic characteristics, making it suitable for application in magnetoelectric devices. Voir les détails

Mots clés : dielectric response, Fe-doped PbTiO3, Magnetic Properties, multiferroic ceramics, piezo- electric properties

Influence of isothermal aging in LDX 2101 duplex stainless steel on the microstructure and local properties

N Ouali, B Cheniti, B Belkessa, B Maamache, R Kouba, M Hakem  (2021)
Publication

In the present work, the interface morphology and the evolution of nitride precipitates in LDX 2101 stainless steel isothermally treated at 750 °C for various aging times were investigated. The microstructure results showed that the Cr2N nitrides precipitated along the δ/γ interface with 200 nm in length and continue to grow to 2 μm after 240 h of aging. However, only Cr2N nitrides were found at the δ/δ interface after long term of aging. Atomic force microscopy (AFM) analysis revealed that Cr2N nitrides andCr23C6 carbides started to precipitate after the first 10 min of aging with a small needle shape of the former and specific triangular morphology of the latter. The evolution of hardness and Young’s modulus of the interfaces, performed with nano-indentation measurements, showed that the δ/γ interface became harder (4.1 ± 0.2 GPa) with increasing aging times, whereas negligible changes in the hardness and elastic modulus were recorded at the δ/δ interface. 3D topographic analysis of the immersed surfaces revealed that the susceptibility of δ phase to preferential dissolution in 3.5% NaCl solution increased with aging time. This behavior was manifested by the important imperfections of δ phase, the high surface roughness (55.7 nm), and the deep corrosion pits (30 nm) along the δ/γ interface and around the Cr2N nitrides. Voir les détails

Mots clés : microstructure, Interface, precipitates, Nano-hardness, Surface degradation