Sciences des matériaux
The degradation mechanism of coatings in MgO-C of the steel pockets
Our work has as an aim the study of the influence of the impregnation, by the slag and the molten metal, on the degradation of the refractory brick linings in MgO-C of the steel pockets of Arcelor-Mittal Annaba. Voir les détails
Mots clés : Refractory, pocket with steel, impregnation, slag.
First principle investigation of structural, electronic and optical properties of Er-doped (ZB) ZnO using modified Becke-Johnson exchange potential.
In this work, we investigated the effect of Er, as a dopant element, on physical properties of ZnO. Structural, electronic and optical properties are obtained for 25% of Er doped ZnO in hypothetical zincblend structure. This study done using Density Functional Theory (DFT) with generalized gradient approximation (GGA) and modified Becke-Johnson exchange potential (mBJ). It found that, the calculated energy band gap and the lattice parameter of pure ZnO are close to the experimental ones and was in a good agreement with other theoretical calculations. It also shown that, the incorporation of Er in ZnO affects considerably the electronic and optical properties. For example, the optical energy gap has increased by 83% under Er doping. From imaginary dielectric function, we established that red shift also achieved under Er doping indicating the importance of its 4f donor occupied states. Voir les détails
Mots clés : Er-doped ZnO, FP-LAPW, mBJ potential, Electronic structures, Optical properties.
Study of stuctural , electrochimical and antibacterial properties of PVK pur and Doped with TiO2
Polymeric thin films of poly (N-vinylcarbazole) (PVK) with nano-crystalline titanium oxide (TiO) were fabricated by using bath deposition method. The complexation of the polymer was confirmed by Fourier transform infrared (FTIR) and UV-Visible studies, the antibacterial activity was tested with various percentage, from 1wt%, 3wt%, 5WT% of doping, with staphylococcus aureus, Bacillus subtilis and Escherichia coli in the absence of light. Voir les détails
Mots clés : Poly (N-vinylcarbazole), Antibacterial Activity, Titanium Oxide (TiO 2 ), DMSO
Copper Oxide Thin Films Deposited by Radiofrequency Magnetron Sputtering: 1Photovoltaic Applications
An unbalanced radiofrequency magnetron sputtering, at low pressure argon-oxygen gas mixture, was used to elaborate copper oxide films. Analyses of the deposited layers by X-ray diffraction (XRD), spectrometry UV-VIS-NIR and electrical resistivity measurement were carried out to assist and optimize the method. The apparition of CuO and/or CuO phases is affected by the experimental plasma parameters. So it’s important to find the best operating range ensuring the correct stoichiometry and giving the preferred phase. The results showed a changing films color with resistivity ranging from 10 to 570Ωcmandfilmsthicknessfrom0.24to2.2μm. Voir les détails
Mots clés : solar cells, Copper oxide thin films, Magnetron sputtering
The influence of annealing temperature and mercury doping (Hg) on nanostructures thin films of TiO2 obtained by sol-gel method
This work is a study of Hg+2 doped TiO thin films deposited on silicon substrates prepared by sol-gel method and treated at temperature ranging between 600 to 1000 ° C for 2 hours. The structural and optical properties of thin films have been studied using different techniques. We analyzed vibrations of chemical bands by Fourier transform infrared (FTIR) and optical properties by UV-Visible spectrophotometer (reflection mode) and photoluminescence (PL). The X-ray diffraction and Raman spectra of TiO thin film, confirm the crystallization of the structure on anatase, rutile and mercury titanate oxide (HgTiO) as function of the annealing temperature. The observation by scanning electron microscopy (SEM) shows the changing morphology of nanostructures with annealing temperature. The 3photoluminescence and reflectance spectra indicate that these structures should enhance display photocatalytic activity. 22 Voir les détails
Mots clés : TiO2 -Hg, sol-gel, Structural properties, nanostructures, nanotubes, Optical properties.
Production and characterization of a composite deposit on steel Nickel-Alumina
The need for improving the coatings with better corrosion resistance has been developed by the use of composite electrodeposits, which consists on adding solid particles in the structure of nickel, such as aluminium oxide (Al). The objective of this research is the study of the resistance of nickelaluminacomposite coatings on steel substrates (black plate), obtained from electroplating bath, at different levels of Al concentrations. The characterization is made by tests of corrosion in two different electrolytic solutions 0,5M K and 0,5M NaCl, and physicochemical analyzes such as the X-rays diffraction (XRD) and scanning electron microscopy (SEM) with the microanalysis (EDAX). The electrochemical behavior of composite coatings in corrosive solutions was checked by methods of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The various tests, carried out in theses conditions, revealed that the particles of Al added to the bath decrease the corrosion tendency of covered steels. They also determined the concentration of Al2O32, added to the bath, which provided the optimal protection against corrosion. Voir les détails
Mots clés : electrodeposition, Composite coating Ni-Al 2 O 3, Electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization
Characterization Of Synthesised Layered Double Hydroxides Materials
In this study, layered double hydroxides are synthesised by co-precipitation and reconstruction method. Layered double hydroxides were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, surface measurment by Brunauer, Emmett and Teller method, and determination of point zero charge pH. Calcined layered double hydroxide are obtained by thermal treatment. The removal of water and carbonate during calcination lead to the formation of channels and pores which increased its specific surface area. The The X-ray pattern of calcined LDH show that the structure was destroyed and converted to an amorphous material after calcination and can be reconstructed by simple contact with anionic solution. The point zero charge pH value of these solids confirm that these materials are a good candidate for adsorption and catalysis applications. Voir les détails
Mots clés : co-precipitation, layered double hydroxides, calcination, characterization
Elaboration and Characterization of Cadmium Sulfide (CdS) Thin Films Prepared by Chemical Bath Deposition (CBD)
Our work consists in elaboration and characterization of cadmium sulfide (CdS) thin films. Indeed, in order to deposit a series of these films, we have adopted a simple and cheap technique, such as the chemical bath Deposition (CBD). The series of samples of CdS was deposited on glass substrates by varying the deposit bath temperature from 55 to 75 ° C and by keeping the deposition time fixed (25 min). Our investigation is focused on the understanding and study of the effect of the deposition temperature on the physical properties of the thin films to which it was referred. For this purpose, we used two characterization techniques which are: the X-ray diffraction (PANalytical X-ray diffractometer) for determining the structure of the films and also, the UV-Vis spectroscopy (UV-3101 PC-SHIMADZU double beam spectrophotometer) for determining their optical properties. Thicknesses (d) of CdS films was measured with gravimetric weight different method using a sensitive electronic microbalance and were confirmed by using a profilometer of the type KLATENCORP6. The structural characterization indicates that the structure of CdS films obtained is cubic or hexagonal with preferential orientation in accordance with the plane (111) or (002), respectively. The optical characterization shows that these films have a fairly high transparency which varies between 55 and 80% in the visible range of the optical spectrum, the optical gap value of which can reach 2.2 eV. It can be suggested that these properties make these films perfectly suitable for their use as window film in solar cells in thin films. Voir les détails
Mots clés : Thin films, chemical bath, Cadmium Sulfide, optical properties, Structural properties
Microstructure development during pack aluminization of Z60CDV5 steel.
Aluminium was deposited on the surface of steel by the pack cementation method in active medium to improve its hight temperature oxidation resistance.In this research, coating of aluminium was applied on Z60CDV5 hot work tool steel substrate. The growth kinetics of these Al-rich intermetallic shells are studied as a function of alumunization time and pack activity at 1050°C. The (OM) results showed that the aluminized coating consisted of different layers.The XRD results have shown that the structure of the layer is mainly composed of the α solution and intermetallic FeAl, FeAl₂, Fe₃Al and others, according to the Fe-Al phase diagram. However, the shape and extent of each intermetallic depend on the sample holding time in the active medium and the treated steel composition. The uncoated and coated spicimens were subjected to isothermal oxidation until 1000°C. The oxidation results revealed that the application of a coating layer increased of oxidation resistance of the coated Z60CDV5 samples as opposed to the uncoated one. Voir les détails
Mots clés : Aluminization, Qxides, Intermetallic compound, Hight temperature oxidation
Synthesis, structural and optical properties of ZnO thin films
In this study we have investigated an economical route for the synthesis of ZnO thin films by sol-gel technique associated with spin-coating deposited onto silicon substrates post annealed at 550°C. Characterizations of the samples were performed by X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and the diffuse reflectance of the films was measured using UV-VIS-NIR spectrophotometer. X-ray diffraction (XRD) of the films showed a hexagonal wurtzite-type structure with a preferential orientation according to the direction . Scherrer’s formula was used to calculate crystallite size. AFM study revealed spherical uniform morphology of ZnO films. Finally, the various optical constants and the optical conductivity were measured. Voir les détails
Mots clés : Oxidize zinc (ZnO), Thin films, sol-gel, spin coating, Force atomic microscopy, optical properties