Sciences des matériaux
Vegard's Law in the Si1-yCyalloys
In this work, we presented a calculated ofstructural properties of the Si1-yCbinary alloys, the atomicstructure of this alloys is important for understanding itsproperties. We used theories of bond-length of Vegardsapproach based of the method of linear augmented plane wave(FP-LAPW) based on the theory of density functional (DFT). Wealso studied the structural properties of this alloys with the LDAapproximation for the potential for exchange and correlation.Our study affirms that the lattice constant is approximately equalto the composition-weighted average of the lattice constants ofthe pure materials. Voir les détails
Mots clés : Vegarslaw, Structural properties, SiC
Modélisation et Simulation Numérique desEngrenages Plastiques (PVC, PA)à DentureHélicoïdale sous un Environnement C.A.O"Application du Logiciel SolidWorks 2013+ Comsol4.4"
les recherches dans le domaine des engrenages sontpenchés vers lamélioration du rendement, et la diminution dubruit que provoque cette transmission et ce parlamélioration des caractéristiques des matériaux utilisés oupar létude dautre matériaux comme les matériaux plastiques.Dans cette étude nous avons présenté une simulation numériqueet aussi lanalyse statique et dynamique des engrenagesplastiques sous un environnement C.A.O, cette simulation sefait à laide des logiciels CosmosWorks intégré à SolidWorks+Comsol 4.4. Voir les détails
Mots clés : Engrenages Plastiques, Conception Innovante, Cosmos Works, PVC, PA
Mechanical Characterization of a new hybridJute/ Glass reinforced laminates
The greatest challenge, nowadays, in all science fields is toface the rarefaction of fossil resources. The solution in civilengineering and in transportation is to lighten theconstruction materials. For this end, the compositematerials have been, logically, i mposed since the secondhalf of the past century thanks to their specific mechanicalcharacteristics. In the two last decades, extraction and useprocedures of natural fibers have known an i mportantincrease for the reinforcement of composite materialscalledBiocomposites.This category of fibers possesses a lot of advantages uponthose traditional synthetic such as: Abundantly available,reduced cost, lightness and satisfactory specificperformances. The current study has the ai m ofcharacterizing a new hybrid laminate made up of 4 plies; theupper and lower ones are reinforced with glass mat fabricswhile the two central ones are reinforced with natural Jutewoven fabrics.The main idea of this work is to preserve sufficientmechanical characteristics by reinforcing the most solicited Voir les détails
Mots clés : composite materials, natural fibers, laminates, hybrid reinforcement.
Élaboration et Caractérisation des MembranesNano-bio-composites
Lévolution des matériaux polymères est passéeprincipalement sur le développement des matériaux nano-composites [1], laugmentation continue et lutilisation de cesmatériaux causent des dégâts irréversibles qui nuisent àlenvironnement de façon inquiétante. Pour cela, ces dernièresannées les industriels sintéressent aux nano-bio-composites pourremédier à certaines complications nuisibles. En dépit, deséléments naturels et biodégradables sont utilisés pour leurapplications variables dans différents secteurs (biomédical,alimentaire, agricole)[2].Nous nous intéressons dans ce travail, aux nano-bio-compositesChitosane/PVA/Na-MMT. Les résultats de la DRX ont montré laréussite du traitement de largile fig.1. Le test mécanique entraction et dabsorption deau, ont montré que largile traité NaMMTaméliore le module de Young des mélange polymèreCH/PVA, et le taux dabsorption, respectivement. LanalyseMEB/EDS a bien montrée la bonne dispersion des particulesdargile dans les phases polymériques. Voir les détails
Mots clés : nano-bio-composite, Na-MMT, Chitosane, PVA.
Thermo-mechanical beahvior of steel-concretecomposite columns under natural fireincluding heating and cooling phases
In recent years, concrete filled tubular(CFT) columns have become popular among designersand structural engineers, due to a series of highlyappreciated advantages: high load-bearing capacity,high seismic resistance, attractive appearance, reducedcolumn footing, fast construction technology and highfire resistance without external protection. In a fire, thedegradation of the material properties will cause CFTcolumns to become highly nonlinear and inelastic,which makes it quite difficult to predict their failure. Infact, it is possible to fail during heating or cooling phaseof fire. In this paper, the behavior of axially loadedconcrete filled square hollow section columns subjectedto natural fire conditions has been studied. The mainobjective of this study is to highlight the phenomenon ofdelayed collapse of this type of columns during or afterthe cooling phase of a fire, and then analyze theinfluence section size. The results show that criticalconditions with respect to delayed failure arise muchmore for massive sections. Voir les détails
Mots clés : Natural fire, Fire resistance, composite column, cooling phase, residual strength
Structural characterisation and antibacterial activity ofPP/HDPE/TiO2-clay nanocomposites prepared by reactive extrusion
Compatible blends of polypropylene(PP)/hight density polyethylene (HDPE)were prepared byreactive blending in the presence of dicumyl peroxide (DCP)anhidride malic (MAH). The blends were characterized usingdifferent techniques: dynamical rheological analysis (DRA),differential scanning calorimetry (DSC), optical microscopy(OM) and scanning electron microscopy (SEM), dynamicalmechanical thermal analysis (DMTA), and impact strength, toevaluate their properties. The antibacterial properties ofPP/HDPE/TiO2-clay nanocomposites on E. coli Bacillus subtilisand S. aureus have been studied. Voir les détails
Mots clés : pp, ( dcp ), nanocomposite, antibacterial properties
Synthesis and characterization of antibacterialsilver-alginate - chitosan bionanocomposite filmsusing UV irradiation method
A simple, UV-based method for the preparation of alginate-silvernanoparticles-chitosan composite films is described herein. Alginate,a polysaccharide was simultaneously used as a natural stabilizer andreducing agent of silver ions (Ag+) delivered from silver nitratesolution. The properties of silver nanoparticles (Ag NPs) in alginateand alginate-Ag NPs-chitosan (Alg-Ag NPs-CTS) composite filmswere investigated in terms of their surface plasmon resonance (SPR),crystalline structure and morphology. The average diameter size, thedegree of swelling and functional groups distribution were alsoaddressed. Antibacterial activities were carried out against bothGram+ and Gram- bacteria cells; the synthesized nanocompositefilms displayed an interesting antibacterial activity. The perspectivesfor a potential use of these nano-composite films in areas such asbiomedical engineering may seriously be considered. Voir les détails
Mots clés : alginate, silver nanoparticles, green synthesis, chitosan.
Microstructural and tribological characterizations of a Hard material composite: WC-WMn-Ni/Cu-Sn/assembled with cermet (WC-Co) by brazing process.
This study focuses in microstructural and tribological characterizations of an assemblage.This assemblage is a Hard Materiales composite obtained by infiltration process of loose powder(WC/WC- W-Cu-Mn-Ni) using bronze alloyed with Ni as binder, assembled with cermet (WC-Co) bybrazing process using filler metal of Ag basic(Ag21Zn16Cu8Mn5Ni),2Hard Materiales composites or Cemented carbides are heterogeneous materials [1]; they are a classof metal matrix composites (MMCs) [2].The main feature of the hard metals composites is the combination of a tough metal binder with ahard material phase. This arrangement of phases offers an enhanced performance of certain materialproperties such as an excellent wear resistance [3_5]. This assemblage used in our study is similar tothe Diamond tools with PDC (Polycrystalline Diamond Compact) obtained by infiltration and brazingprocess, used in the field of oil and mining.Microstructural characterizations show a strong interaction between the binder phase andcompounds of powder in the infiltration process. The interface formed by the brazed joint is due tothe wide diffusion between the two assembled materials and there is formation of an inter-diffusionzone. Tribological caractérisations show, the wear behavior of materials is a complicatedphenomenon due to many variables governing it, such as sliding parameters, materials properties,abrasive effects etc. Voir les détails
Mots clés : powder, infiltration, Brazing, diffusion, interfaces, wear.
CHARCTERISATION MICROSTRUCTURALAND MECHANICALOF Ni/NiAl2O, DEVELOPED BYMECHANICAL ALLOYING AND REACTIVE4SINTERING.
This study concerns the development of Nickelmatrix composite; this composite was obtained after high-energyball milling for long time of milling. The initial powders mixedare the Nickel oxide and Aluminum, the reduction of Nickel oxideby Aluminum called Aluminothermic reaction. The high energymilling active the aluminothermic reaction and occurred theNickel-based composite, after milling we obtained powdercomposite with low density, which it necessary to following thisprocess by reactive sintering. The milling and the sintering wasperformed under argon atmosphere. The reactive sintering athigh temperature allows composite with high density. Aftersintering at 800 °C we obtained Ni/NiAl2O4.The powders milledand the samples sintering were characterized by X-raydiffraction, scanning electron microscopy, and the grain size ofpowders milled measured by laser analyzer granulometry. TheNickel aluminate (NiAl2O4) obtained has been applied innumerous fields to its high thermal stability and specific catalyticproprieties. Voir les détails
Mots clés : Ni/NiAl 2 O4, reactive sintering, reactive milling, powder metallurgy, Aluminothermic reaction.
Elaboration and Tribological study of WC-35wt%(Fe-Co-NI)hard metal alloys obtained by liquidphase sintering
this study concerns on the mechanical behavior(friction wear) of WC-35wt% (Fe-Ni-Co)hard alloy. The alloywas prepared by liquid phase sintering process with atemperature of 1350 ° C under argon. Haw ever This alloy isworking under severe conditions of wear and friction. haveundergo a series of dry friction tests involving multipleparameters. Interesting results have been obtained (good wearresistance and a stabilization of the friction coefficients). Thewear rate (mm3 / m) increases with increasing of the applied load5N and 10N, these results open up broad prospects for their jobsin the petrochemical fields (drilling tools, turbine parts). Voir les détails
Mots clés : friction, WC, phase, alloys, Sintering, wear