Sciences et génie des matériaux

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Corrosion of AISI4130 in différents électrolytiques solution

ALLOU Djilali, MIROUD Djamel, CHENITI Bilal  (2018)
Article de conférence

This article discusses the electrochemical behavior of AISI 4130 alloy steel in various electrolyte solutions H2SO4, HCl and NaCl. Corrosion tests were carried out on a potentiostat / galvanostatat room temperature in the various electrolytes, under an Ag / AgCl reference electrode with .Electrochemical Impedance Spectroscopy (EIS) measurement. The results obtained through the tafel curves show that the corrosion process can be divided in two parts highlighting the aggressivity of Cl- ions. The impedance which is characterized by a large semicircle in the Nyquist graph increases under H2SO4.Equivalent circuits have been determined to represent the corrosion processes at differente ectrolytes. Voir les détails

Mots clés : AISI 4130, electrolytes H2SO4, HCl and NaCl

Modal Analysis For Composite Sandwich Plates Of Honeycomb Core

Gaagaia, Guenanou, Ahmed Belaadi, Aouaichia, Bouakba, Fergani  (2018)
Article de conférence

.The purpose of this work is to realize a vibratory study on panel’s sandwiches established by the honeycomb core and aluminum skins, used in the conception of the aerospace structures; all the analyses are based on conditions in the embedded free limits (E-L-L-L). The aim is to compare the natural frequencies of the two plates with those obtained from the two simulation models. Two methods are used in modeling, 3D drawing of the sandwich structures and calculating an equivalent structure using the homogenization method based on representative elementary volume (REV) using ANSYS software. The modal resolution of these two configura-tions is performed by the finite element method. The comparison of numerical results shows excellent agreement. Voir les détails

Mots clés : Sandwich plate, homogenization, FRF's, modal analysis, Finite element method.

Extraction of green inhibitor and study of their antioxidant effectiveness of ecologicalcorrosion

Souad brick chaouche, Haddad Ahmed  (2017)
Article de conférence

Several methods are available to prevent or retard corrosion ofmetallic materials, the use of inhibitors is one of the besttechnique to ensure their protection in contact with aggressivemedia such as hydrochloric acid medium. The environmentaltoxicity of organic corrosion inhibitors has prompted thesearch for green corrosion inhibitors as they are biodegradable,do not contain heavy metals or other toxic compounds. As inaddition to being environmentally friendly and ecologicallyacceptable, plant products are inexpensive, readily availableand renewable. The objective of this work is the extraction oflimonene from orange peels and study their effectiveness onthe corrosion of X42 steel in HCl medium. The analysis ofinhibitor was evaluated by chemical methods, and theelectrochemical study shows that the addition of limonene tothe medium induces a reduction in the corrosion rate of thesteel in HCl medium. Other parameters may influence itsinhibitory activity such as immersion time, concentration ofinhibitor, the nature of media (acidic or basic). Voir les détails

Mots clés : Metal and alloys; Acid medium; corrosion inhibitors; Green inhibitors; limonene

EVALUATION OF MECHANICAL STRESS EFFECT ON THE PROPERTIES OFSTAINLESS STEEL SURFACES BY SECM, SKP, SVET AND LEIS

Ahmed HADDAD, ZIOUCHE Aicha, Yahi sara, Souad brick chaouche  (2017)
Article de conférence

Mechanical stress or fatigue cracks originate from varioussurface imperfections, such as inclusions, pits, or residualstress. It is very important to use a method to predict thelikelihood of environment-assisted cracking or pitting corrosion.The austenitic stainless steel shows high corrosionresistance level. It knows that plastic deformation decreaseit's resistance. The corrosion form in case of this steel is veryspecial and the corrosion tests are difficult. The investigationof Scanning Kelvin Probe (SKP), s canning vibrationelectrode technique (SVET) and localized electrochemicalimpedance spectroscopy (LEIS) to evaluate the influence ofmechanical stress on the electrochemical properties ofaustenitic stainless steel 316L.We tested the selected steel about its corrosion behaviour afterhigh rate deformation. We wanted to find a relationshipbetween the corrosion resistance decreasing and the rate ofthe plastic deformation. Plastic deformation effect of thecorrosion resistance in case of austenitic stainless steel Voir les détails

Mots clés : SKP, SVET, LIES, corrosion, austenitic, plastic deformation 316

Investigation of WC decarburization effect on the microstructure and wear behavior of WC-Ni hardfacing under dry and alkaline wet conditions

B. Cheniti, D. Miroud, P. Hvizdoš, j. Balko, R. Sedlák, T. Csanádi, B. BELKESSA, M. Fides  (2018)
Publication

The performance of drilling tools hardfacing in different conditions is strongly related to microstructural aspect of the coating and to the adhesion with the substrate. In the present investigation, the manual oxy-acetylene brazing process was employed for AISI 1020 steel hardfacing using WC-Ni. The substrate/hard facing interface was particularly studied which was a Ni-Cr-Al-Mo interlayer prepared by flame thermal spray method. The microstructural results exhibit a good embedding of WC particles into the Ni matrix, where the inter-diffusion of Ni, Cr, and Fe elements at the interface is enhanced using the interlayer. The dissolution and decarburization phenomena of WC particles with the formation of W2C eutectic phase and their effect on the decohesion and pull out of the particles during the wear test were studied. The hardness (HIT) and Young's modulus (EIT) of different parts of the hardfacing were investigated by instrumented nanoindentation. The wear resistance of the surface coatings under alkaline condition using sodium hydroxide (NaOH) basic solution of pH?=?12 is two times higher than under dry condition. Furthermore, the formation of SiO2 third body stripes along the wear track promotes the decrease of the friction coefficient and the volume loss. On the other side, the wear mechanism is adhesive with severe plastic deformation of the Ni matrix in dry condition and oxidative/abrasive wear in alkaline wet condition. Voir les détails

Mots clés : Interface, WC dissolution, Hardfacing, inter-diffusion, Decarburization

Effect of brazing current on microstructure and mechanical behavior of WC-Co/AISI 1020 steel TIG brazed joint

B. Cheniti, D.Miroud, R.Badji, D.Allou, T.Csanádi, M.Fides, P. Hvizdoš  (2017)
Publication

In this work, the WC-Co carbide/1020 steel brazed joints which were prepared by Tungsten Inert Gas (TIG) process using different brazing currents have been studied. The peak temperature reached by increasing the brazing current caused remarkable inter-diffusion of Ni, Mn, Cu and Co elements between the braze and the base materials. The higher the brazing current was, the larger the diffusion extent of these elements became and the greater the WC rearrangement occured. As the diffusion rate of Ni towards the WC-Co was enhanced through increasing brazing current, a short range diffusion of Co element towards the braze was recorded. A Special Shear Test (SST) conducted at room temperature revealed the best bonding strength for the current of 80A. Besides, hardness (HIT) and elastic modulus (EIT) values of the interfaces were situated between those of the braze and the base materials. Voir les détails

Mots clés : WC-Co cemented carbide, TIG brazing, inter-diffusion, Interface, Nano-indentation

Valuation of mill scale as iron pigments for painting anticorrosive.

Belgacem BEZZINA, Mohamed Tayeb ABEDGHARS, Hocine BENDJAMA, Salah Bouhouche  (2017)
Publication

The mill scale is a steelmaking byproduct. This work focuses on the valuation of the steel waste and its transformation to a usable product in the field of anti-corrosion paints. These iron oxides have been examined as a pigment and corrosion inhibitor in two types of paints with different concentrations (1 %, 3 %, 7 %, and 15 %) to determine the best formulation. Their properties were compared to that of an anticorrosion paint trademark based on iron oxide. For this purpose various techniques of mechanical and physical-chemical analysis were used; grinding is applied to pieces of mill scale for very fine powders (< 32 μm); the particle size of the milled scale analysis, to determine their particle size distribution; a primary electrochemical method used to evaluate the performance and scale vis-à-vis the phenomenon of corrosion behavior, and a UV-Visible spectroscopic method for determining the concentration of total dissolved iron. The experimental results showed that the anti-corrosion properties or rather inhibition efficiency increases with increasing concentration of the mill scale in the tested paints. Voir les détails

Mots clés : mill scale, corrosion inhibitor, spectroscopic, electrochemical analysis

Exploitation des sous-produits sidérurgiques du complexe Elhadjar -Annaba-.

Belgacem BEZZINA, Mohamed Tayeb ABEDGHAR, Oualid GHELLOUDJ, Chems Eddine RAMOUL, Kheireddine SLIMANI, Toufik CHOUCHANE, Djameleddine KHATMI  (2017)
Article de conférence

Le présent travail de recherche se base sur l'exploitation du sous-produit sidérurgique (calamine) et sa transformation en produit utilisable dans le domaine des peintures anticorrosion. Ces oxydes de fer ont été examinés comme pigment et inhibiteur de corrosion dans deux types de peintures à concentrations différentes (1%, 3%, 7%, 15%) pour déterminer la meilleure formulation. Le meilleur temps de broyage de calamine est 2 minutes avec une distribution volumique D(0,9) des particules à une taille inférieure de 32 micromètre et une surface spécifique égale à 1.6 m2/g. L’analyse chimique montre une teneur en fer total moyenne de 72 % et des faibles teneurs en des oxydes de manganèse et de silice. L’analyse électrochimique a prouvé que les propriétés anticorrosives ou plutôt le rendement d’inhibition augmentent avec l’augmentation de concentration de la calamine dans les peintures testées (15% pour Glylac et 7% pour Glycar). Voir les détails

Mots clés : calamine, agent anticorrosif, analyse granulométrique, analyse électrochimique.

Dephosphorization of Western Algerian Oolitic iron ore

Belgacem BEZZINA, Mohamed Tayeb ABEDGHARS  (2017)
Article de conférence

A Combination of roasting and acid leaching processes was tested for the dephosphorisation of Gara Djebilet oolitic iron ore (Algerian Western Sahara) that contains a high phosphorus content of 0.91% which exceed-acceptable limits. A laboratory scale, this process involving a chemical attack after roasting of the raw sample of iron ore that mixed with alkaline additives (CaCl 2 or NaCl) followed by an acid leaching using nitric acid, perchloric acid, hydrochloric acid and sulfuric acid. 89% of phosphorus is removed by the addition of the salt (NaCl) then attacked by nitric acid. The laboratory tests carried out for a dephosphorisation show that the combination of roasting with alkaline additives, followed by an acid leaching makes it possible to obtain high quality iron concentrate. Despite the phosphorus content decreases from 0.91 to 0.1%. Voir les détails

Mots clés : Oolitic iron ore, acid leaching, dephosphorisation, alkaline additive.

Experimental investigation of the polymer material (HDPE) behavior welded by FSW

S. Ameur, B.O. Chikh, H.M. Meddah, B. Bouchoicha and M. Bendouba  (2017)
Article de conférence

This work contributes in the knowledge of the process of friction stir welding, and its use for the first time in a polymer material, it is the high-density polyethylene material widely used in gas transport and other applications. Welding and friction stir is a rapid and a controlled process to achieve strong and sustainable mechanical connection plates welded on. Simple Tensile tests were conducted in order to characterize the parameters of HDPE welded and not welded. We found that the FSW can be used in the welding of this material. Voir les détails

Mots clés : HDPE, welding, FSW