Sciences des matériaux

Nombre total de résultats : 442
Pertinence Titre A-Z Plus récents Plus anciens
10 25 50
Année de publication

Numerical study of polymer coating by UV photopolymerization.

Article de conférence

Polymer-based coatings are used to protect a structure or device against mechanical attacks such as scratches, abrasion and erosion or against chemical attacks such as humidity, temperature, UV rays. This work concerns the development by photopolymerization UV of new coating materials based on a polymer as (Polyurethane Acrylate, oligomers) deposited on heat-sensitive materials such as thermoplastics (PC; PMMA,). Now, the polymers, which are already used in thermal powder coating. They generally show very high melting temperatures (around 200 °C). They will not be suitable for depositing on supports sensitive to high temperatures without risk of damaging them. In this work, we proposed a numerical study of the effect of different synthesis parameters (energy and applied UV rays, exposure time, temperature, external medium, etc.) on the conversion rate to a 3D mesh (crosslinking rate) and model optimization of coating parameters on heat-sensitive substrates. Voir les détails

Mots clés : polymers, coatings polymer, photopolymerization UV

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

Comportement mécanique et métallurgique des jonctions hétérogènes soudées par friction rotative

Mémoire de Master

Rotational friction welding is a solid state welding process, which has seen spectacular development in various industries. It offers the possibility of producing very high quality solder joints in an extremely short time. The objective of this work is to improve the operating parameters of this process by changing the friction time (periods) and fixing the other parameters namely the speed of rotation [round per minute], the forging time [s], the friction and forging pressure [MPa]. The major problem with the disimmilar assembly of aluminum and stainless steel alloys is the low mechanical strength in the welded joint, due to the formation of certain unwanted inter-metal compounds during welding. An experimental procedure was used to obtain an Al6013-T8 /304L stainless steel welded joint with and without copper insertion. Different characterization methods were used namely x-ray diffraction, optical microscopy, HV microhardness and tensile testing. The Al6013-T8 side microstructure reveals the formation of two zones, the HAZ and the TMAZ at the center of the junction, unlike 304L stainless steel, which has not undergone any mechanical deformation. The microhardness of Al6013-T8 increased in the vicinity of the junction, and tensile testing revealed that the mechanical characteristics of the joints increase with increasing friction time. Voir les détails

Mots clés : Rotational friction welding, the speed of rotation, the forging time

Etude mécanique et microstructurale des soudures des alliages d'aluminium soudées par friction

Mémoire de Master

This work is related to the study of the friction welding process. This type of welding has many applications in different branches of industry. This process has many advantages. First, the very high quality assemblies can be made. In addition, this process is much faster than any other conventional processes. Furthermore, it can be completely automated so that constant quality is guaranteed. The aim of this study is the optimization of the parameters of friction welding: (by varying the friction time [s] and the rotational speed [rpm], forging time [s] and the friction pressure and forging [MPa] remain constant). An experimental procedure was used to obtain a welded junction (alu-alu), the alloy used is Al 6013-T8. We used several characterization methods, simple but effective and suitable for this kind of research work; such as microstructural characterization by optical microscope and mechanical characterization namely microhardness and tensile testing. We observed that the microstructure has three zones (TMAZ, HAZ and MDZ), The microhardness profile has a certain homogeneity and the tensile tests have shown that the tensile strength, elongation and elastic limit increase with increased friction time. In general, the mechanical properties are influenced by the overall effect of the metallographic structure of the weld. The latter is closely linked to the process parameters. Voir les détails

Mots clés : Friction welding, 6013-T8 alloy, Welded joint, mechanical properties, microstructure, Microhardness

Effet de l’application d’une peinture anti-corrosion sur le comportement électrochimique de l’acier au carbone en milieu acide

Mémoire de Master

In this work, we are interested in the evolution of the surface roughness of steel (mechanically polished (A2, A3) and shot-blasted (A2G, A3G)) and the thickness of the paint applied to different surface states (mechanically polished (A2P, A3P) and shot blasted (A2GP, A3GP)). Shows that the roughness of grit-carbon steel surfaces is greater than the mechanically polished ones. Although the evolution of the thickness of the paint deposited on mechanically polished and shot-blasted carbon steel, depending on the grade of polishing paper,), shows that the thicknesses of paint deposited on carbon steel surfaces shot blasted are larger than those polished mechanically. The characterization of the samples was determined by scanning electron microscopy (SEM), showing that the surface state of mechanically polished steel (A3) is much better than that of shot-blasted steel (A3G). The surface analysis by SEM also shows that the coatings applied on the shot-blasted steel (A3GP) have a much better morphology than those applied on mechanically polished steel (A3P), and the metallographic micrographic analysis shows that the thickness of the coatings of paints obtained on shot-blasted steel are superior than that obtained on mechanically polished steel, The effect of mechanical polishing and shot blasting on the behavior of carbon steel with respect to corrosion by the use of two electrochemical techniques: potentiodynamic method and electrochemical impedance spectroscopy (EIS). mechanically polished and shot-blasted steel with and without coating for better resistance to corrosion in hydrochloric acid medium. Spectral analyzes by FTIR, shows the evolution of chemical bonds and functional groups present in the paint applied to steel. Voir les détails

Mots clés : surface roughness of steel, shot-blasted steel (A3G), electron microscopy (SEM)

Elaboration et caractérisation des composites stratifiés à base de fibres de carbone et de fibres de verre à usage aéronautique

A. r. OUKAZI  (2019)
Mémoire de Master

This work is based on the elaboration and the characterization of different types of laminated composites based on epoxy resin, carbon fiber and glass fiber. These composites differ based on three essential parameters, including the type of reinforcements used, the orientation of the constituent fibers reinforcements and the heat treatment temperature at which these laminated composites were exposed. The characterization is then done to see the influence of these elaboration parameters on the physical and dynamic behaviors of this laminated composite materials developed during and after the solicitation. For this, we used nondestructive testing methods such as ultrasound and microscopy and destructive methods such as tensile and bending tests. The results obtained from the various tests were the subject of comparative interpretations followed by interesting perspectives. Voir les détails

Mots clés : Laminated composites, carbon fiber, Glass fiber, Epoxy resin, nondestructive test, mechanic tests

Détection, positionnement, localisation et identification des défauts dans les matériaux solides par ultrasons

Mémoire de Master

In this study, we have been adapted to the various techniques of non-destructive testing and especially non-destructive ultrasonic testing by contact of a piezoelectric transducer with welded parts (different types of welding). This method can detect, locate, dimension and identify defects in the weld seam after going through several steps such as calibration and tracing of the distance amplitude curve. The ultimate goal of this control is to accept or reject controlled parts according to international standards Voir les détails

Mots clés : Non-Destructive testing, piezoelectric transducer, different types of welding

Contrôle du joint de soudure d’un pipeline par ultrasons

Mémoire de Master

In this study, we have been adapted to the various techniques of non-destructive testing and especially non-destructive ultrasonic testing by contact of a piezoelectric transducer with welded parts (welded pipe). This method can detect, locate, dimension and identify defects in the weld seam after going through several steps such as calibration and tracing of the distance amplitude curve. The ultimate goal of this control is to accept or reject controlled parts according to international standards Voir les détails

Mots clés : Non-Destructive testing, - ultrasonic testing, welded pipe

Prediction of the Friction Coefficient of 13Cr5Ni2Mo Steel Using Experiments Plans-Study of Wear Behavior

Soumaya MEDDAH, Mounira Bourebia, Amel Oulabbas, Chams eddine Ramoul, Samira TLILI, Ahlem Taleb, Sihem ACHOURI  (2019)

Metal materials used in industrial applications deteriorate under the effect mechanical and chemical phenomena occurring under operating conditions, such as pipes carrying gas or fluid that are subject to internal wall wear. From where an experimental study was conducted through friction tests on supermartensitic stainless steel Cr13Ni5Mo2, in order to estimate the effect of test parameters on friction coefficient and wear behavior of this steel by adopting the factorial plans 22 methodology at two factors (Load "P" and linear sliding "V"), each at two levels (-1, +1). The results have been demonstrated using a mathematical model predicting the coefficient of friction "f" in every point of the study field. The factorial plans make it possible to establish a modeling of the studied phenomenon with a maximum of efficiency and a minimum of experiences. The experimental results showed that the friction coefficient "f" reaches a max value for an applied load P=10N combined with a linear speed V=5cm/s. In addition, the wear morphology of surfaces after the friction test indicates that for 2N and at all speeds, friction is dominated by an abrasive wear mechanism. However, for 10N, it is observed the predominance of adhesive wear with a higher wear rate. Voir les détails

Mots clés : friction, factorial design, Mathematical model, wear mechanism

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

Samira TLILI, Saida Bouyegh, kotbia LABIOD, Noura Traiaia Mohamed Hassani, Bilal Ariche  (2021)
Article de conférence

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