Defect and Diffusion Forum Vol. 397

Abstract: In this work, ZnO thin films grown on heated glass substrates in a temperature range of 300 to 500 °C with a 50°C step. The prepared solution is composed of methanol and zinc acetate Zn(CH₃COO)₂.2H₂O. ZnO thin films are deposited by pyrolysis spray technique, our work focuses on the study of the substrate temperature influence on the structural and optical properties of these layers. Therefore, The X-ray diffraction, showed a Wurtzit hexagonal structure of elaborated films, with (002) as a preferred orientation, and a grain size of 64 to 74 nm. The optical transmission spectroscopy UV-Visible, illustrated an increase of optical band gap from 3.19 to 3.25 eV, proportionally with the substrate temperature.

Abstract: In this paper, the influence of immersion time on the structural and optical properties of SnO2 thin films was investigated. A series of samples was deposited by Sol-Gel dip coating method onto glass substrates. The number of layers was fixed at 03, but the immersion time was varied between 01 to 10 minutes. The samples [(3 layers) - SnO2 / glass] were submitted to thermal treatments in air at 500°C during 2h. The specimens are characterized by Raman spectroscopy and UV-Visible spectroscopy. Raman spectroscopy show that the thin films of SnO2 obtained at 06 and 10 minutes of immersion time, are crystallizes in rutile phase. The obtained results of optical analysis showed that the SnO2 thin films are transparent (77-85%) in the visible region and the values of the optical band gap varied from 3.81eV and 3.86 eV.

Abstract: Bonded fibre reinforced polymers (FRP) have been found to be an efficient method for improving the lifespan of fatigued metallic structures and have attracted much research attention. Steel beams can be reinforced in flexure using FRP plates that rely on adhesively bond. In such plated structures, shear forces are developed in the bonded joint and these will be transferred to FRP plate via the adhesion technique, thus, the interfacial stresses will progress consequently, and the debonding may occurs at the plate ends due to high values of interfacial stresses. This original research leads us to predict the interfacial stresses by a numerical study, using a finite element model under ANSYS software and coupling effects of mechanical and thermal loads with fibre orientation. Finally, a parametric analysis is used to identify effects of various geometrical and material properties on the magnitude of stresses values. This analysis is helpful because of the adaptation in the modelling process. It is shown that the bearing capacity of the adhesive joint is significantly influenced not only by the strength model, but also, by the shear modulus, elastic modulus of FRP and the other parameters..

Abstract: A glass system was prepared according to the formula 60mol%B₂O₃ – x mol %barite – (40-x) mol %Li₂O, where x=0, 5, 7.5, 10, 15 and 20 mol%. The amorphous nature of the prepared glasses was confirmed through X-ray diffraction. The prepared glasses were also characterized by FTIR spectroscopy, UV-vis absorption spectroscopy and the differential thermal analysis (DTA). The density is found to increase and this is because of the higher molecular of the added barite. The molar volume also increases with increasing barite content that indicates the structural changes occurred in borate network that were also confirmed using FTIR. Increasing the concentration of barite shifts the UV cutoff edge toward higher wavelengths from about 300 nm at 0 mol% barite to about 400 nm at 15 mol% of barite. Glass transition temperature (Tg) is found to increase with the increasing barite content. When analyzed by photoluminescence, the samples exhibit luminescence emission centered at around 400, 415, 480, 430, 485, 520, 545, and 570 nm when excited at 300 nm wavelength. The emission peaks at 420 nm, and 440 nm were assigned to F center emission. Between 440 nm and 520 nm it is rather the effect of the presence of the impurities.

Abstract: Abstract. In the present work several films of Ti, TiN, and TiCrN have been coated on AISI 316L stainless steel substrates using magnetron sputtering techniques, in order to improve their surface properties. The morphology and structure of the coatings were analysed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical performances skills in an SBF solution and the adhesion of these deposits were studied to understand these behaviors. From the results it was shown the TiCrN deposition presents the lowest corrosion resistance in the SBF solution, while TiN deposit is the most resistant to corrosion resistance in the same solutions, but its critical load (Lc3-TiN), is relatively low and has a risk of delamination which can limit its use. On the other hand, the Ti deposit exhibits a high resistance to corrosion and a high passivation (i_corr (Ti) = 0.57 µA.cm^-2 and Rp (Ti) = 67.98 KW.cm²). The critical load (Lc3-Ti = 43.38 N), the crack propagation resistance (CPRs-Ti = 81.64 N) and the scratch hardness (HSL-Ti = 125.75´10¹² Pa) also testify to its high adhesion to the AISI 316L substrate. Thus the Ti deposit has proved to be the most favorable protective coating for AISI 316L stainless steel in SBF solution.

Abstract: The rolling operation consists of deforming the material by passing it between two rolls whose spacing is smaller than the initial thickness of the sample, the reduction in thickness is obtained discontinuously by successive passes in the rolling mill whose spacing between the cylinders gradually decreases. This operation can influence on the mechanical and microstructural properties of the deformed materials The effect of cold rolled on microstructural evolution and precipitation sequence in Al-Mg-Si alloy has been investigated by using optical microscopy and Differential Scanning Calorimetry (DSC) in this study. The results revealed that the distribution of the grains are elongated along the rolling direction. We also noted that insoluble coarse particles that originated during the manufacturing process of the alloy have become visible after the rolling processes. The dislocations generated by the plastic deformation during cooled rolling constitute preferential sites for the germination and the growth of the phases, which accelerates the kinetics of the precipitation.

Abstract: Undoped and indium (In) doped TiO₂ thin films were deposited by sol-gel method onto glass substrates. Structural, optical and electrical properties of films were studied. X-rays diffraction patterns showed that the TiO₂ films consist of anatase phase. AFM images revealed that the surface roughness of In:TiO₂ films is smoother than that of undoped TiO₂ films. UV–Vis transmittance results showed TiO₂ films have significant optical absorption in the region of 300–350 nm and are fully transparent in the visible. Both film thickness and refraction index in dependence on the fraction of In doping are derived from TE and TM optical guided modes excited in a prism coupler. The optical gap E_g decreases from 3.50 eV for undoped TiO₂ film to 3.43 eV at 2 at.% In doping and then increases for doping with indium at 10 at.%. The electrical characterization shows a maximum electrical conductivity of 2.7 (S/cm) obtained for the film doped with 10 at.% In.

Abstract: In this manuscript, the structural properties such as the distance inter-reticular of samples is studied, In the fact, four samples were used symbolized as follows: E tAg(Å), the only difference is the thickness of the Silver buffer layer (tAg= 0, 50, 100 and 150 Å) to find out how the thickness of this layer depends on the structural characteristics of the Iron thin layer, all samples are deposited using molecular beam epitaxy (MBE) at room temperature onto Si (100) substrate. The structural properties of all samples examined using X-ray diffraction method at small and high angles. The small angles X-Ray diffraction curves confirmed to us that there is a clear difference between the surface structure of the samples by varying the number of Kiessig Fringes, Also high angles X-Ray diffraction curves assured us this difference through the clear variation in the angular positions of the peaks of Bragg and the distances inter-reticular values from a sample to the other.

Abstract: In this paper, the study of precipitation reaction in the aluminum alloy known as AGS 6101. For the case of Cold drawn wires process in the open air space and at room temperature for two years, we inspect first the presence of precipitates in the microstructure and study the effect of heat treatment on the activation of this phenomenon [1]. The second objective of this work is to see the effect of natural and thermal aging on the microstructural evolution of cold-drawn aluminum wires (AGS) 6101 [2-5]. The characterization methods used in this work are optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction.