Liste des communications
Electrical Characteristics of SnS /ZnS Heterojunction
Thin sulphide (SnS) is a promising candidate for a low cost, no toxic solar cells absorber layer. In this paper thin films of SnS were prepared by spray pyrolysis onto glass and ZnS/FTO coated glass substrates at different substrate temperatures in the range 250-400°C. SnS were characterized with X-rays diffraction and scanning electron microscopy and UV visible transmittance. The electrical properties of SnS/ZnS heterojunctions were determined using recording their current-voltage I(V) and capacitance-voltage (C-V) characteristics at ambient and at different measurement temperatures from 28-94°C. The results analysis indicate that the saturation current varied from 0.68 to 2.8 µA and series resistance from 191 to 800 ? , The structures ideality factor is ranged from 1.37 to 2.7. The diffusion potential (Vd) was determined by the intercept of extrapolation of 1/C2-V curve to the abscise axis (V=0) we found Vd values ranged from 0.67 to 1.2 V. Voir les détails
Mots clés : Tin sulfide; thin films; solar cell; spray pyrolysis; SnS/CdS Heterojuction.
SnS Thin Films Prepared by Chemical Spray Pyrolysis method
Tin sulfide (SnS) is interesting semiconductor that found application is several fields such as photovoltaic and gas sensor due to its interesting optical and electrical properties. In the present study, chemical spray pyrolysis deposition (CSP) was used to deposit tin sulfide (SnS) thin films onto glass substrates at 350°C. The starting solutions were prepared by the dilution of SnCl2 and thiourea in distilled water. The structural, optical and electrical, properties of the films were determined using X-ray diffraction, UV visible transmittance and Hall Effect measurements respectively. The influences of flow rate (10, 15 and 20 ml/h) in the structural, optical and electrical properties were determined. The XRD data confirms that the films prepared at low flow rate are a mixture of SnS and Sn2S3 phases. However, when the flow rate is increase; structures of the films are amorphous. From the UV-visible transmittance in the visible range we noticed that films optical band gap value ranged from 1.2 to 1.5 eV. The Hall Effect measurements indicate that SnS thin film exhibits p-type conduction with a conductivity decrease by two orders from 5.15x10-3 to 5.8x10-7 (?.cm)-1. Voir les détails
Mots clés : Tin sulfide, solar cell, UV-visible, spary pyrolysis
Estimated life time in an HDPE pipe with a semi-elliptical defect under internal pressure.
High density polyethylene has been widely used in marine and gas transportation, storm sewers, culverts and city drainage system. Compared with other conventional pipes, it has its own advantages, such as, chemical and corrosion resistance, toughness, flexibility, easy splicing and consequent easy handling and installation. In this paper, and in order to predict the remaining lifetime of a pipe having a defect and subjected to internal pressure, it is necessary to estimate KI stress intensity factor during the propagation of the crack. The finite element method is used to assess the values of the stress intensity factor of an axially oriented semi-elliptical crack located at the inner surface of an HDPE pipe. The crack configuration is described by the relative wall thickness (t/R), the relative crack depth (a/t) and the crack aspect ratio (a/c). The lifetimes presented are discussed according to the size of the crack and the stress intensity factor in each case. Voir les détails
Mots clés : HDPE pipe, Crack, rupture, Finite Element Method FEM, stress intensity factor, Lifetime.
Modeling of Electromagnetic Behavior of CompositeThin Layers using Genetic Algorithm
In this paper, we present a new model using the highfrequency electromagnetic simulator for several binary mixtureswhere the load is in the lossless thin film form with a permittivityof (? = 100, 200, 300, and 400) and for various thickness values ina range of 10 µm to 250 µm with respect to the host matrix. Themodel operates in a variety of frequencies from 8.2 GHz to 12.4GHz. The effective permittivity of composites is evaluated usingNicholson Ross Weir (NRW) algorithm in a rectangularwaveguide. The implementation of NRW algorithm is conductedon various samples simulated by HFSS, in order to estimate thedielectric composite behavior. Furthermore, we employ a geneticalgorithm methodology (GA) for the filling factor optimization ofthe proposed model by Mosallaei. The obtained results show agood agreement with the theoretical models, which ensure thevalidity of our proposed model for characterizing theelectromagnetic behaviour of dielectric thin films. Voir les détails
Mots clés : Thin films, electromagnetic behaviour, dielectric mixtures, Genetic optimization, mico wave.
Etude de l’effet des conditions de polarisation sur le mode de relaxation principale (α) du PLA par la technique des courants thermostimulés (CTS)
Dans ce travail nous nous sommes intéressé à l’étude de l’influence des conditions de polarisation (champ et température), sur le mode de relaxation principal(α) du polylactic acide (PLA) par la technique des courants thermo-stimulés (CTS). L’influence du champ électrique se traduit parune augmentation linéaire de l’intensité du thermocourant relatif au mode α ainsi que celle de la polarisation totale de ce pic, affirmant ainsi le caractère dipolaire de la relaxation. L’élévation de la température de polarisation conduit à une augmentation progressive de l’intensité et de la polarisation jusqu’à saturation au voisinage de la transition vitreuse. Les énergies d’activations évaluées par la méthode des demi-hauteurs, augmentent pour des températures de polarisation inférieures à 70°C, puis rejoignes un palier de saturation. Un tel résultat est dû à un processus thermiquement activé et à une distribution du temps de relaxation. La température de transition vitreuse Tgaugmente avec la vitesse de chauffage. Ce résultat confirme la nature cinétique de la transition vitreuse. Voir les détails
Mots clés : Transition vitreuse, relaxation, PLA, CTS.
EVALUATION OF MECHANICAL STRESS EFFECT ON THE PROPERTIES OFSTAINLESS STEEL SURFACES BY SECM, SKP, SVET AND LEIS
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
NDT Characterization of FeCu Nanostructured
The mechanical alloying process has been used to synthesis Fe-Cu nanostructured powder in a high energy planetary ball-mill PM400. Structural and magnetic, properties of the powders milled were investigated by scanning X-ray diffraction and vibrating sample magnetometer, respectively, the elemental micrometer-sized Cu and Fe powders were first mixed in Fe70Cu30 compositions, the added of Cu in Fe formed the solid solutions of Cu in Fe and Fe in Cu, a solid solution face-centred cubic and solid solution body-centred cubic nanograined composite has been formedKeywords: Mechanical alloying, Fe–Cu alloy, Structural and magnetic. Voir les détails
Mots clés : Mechanical Alloying, Fe–Cu alloy, Structural and magnetic
Extraction of green inhibitor and study of their antioxidant effectiveness of ecologicalcorrosion
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
Eddy current characterization and Magnetic properties of iron alumina nanostructured alloy
The mechanical alloying technique has been used to synthesis iron alumina nanostructred powder in a high energy planetary ball-mill PM400. Electromagnetic and magnetic characterizations of the powders was investigated by eddy current and vibrating sample magnetometer, the impedance, the coercivity and saturation magnetization of the iron alumina mixtures changes in function of x% (wt). Voir les détails
Mots clés : iron alumina, electromagnetic and magnetic properties, Eddy Current, VSM.
A Study of the Behavior of Water Droplets Under The Influence of Non-Uniform Electric Field in Silicon Rubber
Water droplets on the surface of silicon rubberwere investigated under the influence of non-uniform electricfields. Several parameters of water droplets were investigated,such as the positioning of the droplets regarding the electrodes.The most striking conclusion is that the flashover voltage andelectric field distribution depends on the positioning of thedroplets from the electrodes. Voir les détails
Mots clés : water droplets, non uniform Electric field, COMSOL, finite element, insulating barrier, silicon rubber