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 i nsoluble 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.

In this work, we studied the ZnO film thickness effect on the photocatalytic performance of n-ZnO/p-NiO heterostructures. The ZnO and NiO films were prepared by sol-gel dip-coating technique and the thickness of the ZnO film was varied by changing the number of coatingsfrom 2 to12. The formation of the p-NiO/n-ZnO heterostructure was confirmed by X ray diffraction (XRD). The obtained ZnO films present a wurtzite structure with a preferred orientation along (002) direction while the NiO film present a cubic structure highly oriented along (200) direction. UV-visible transmittance spectra of the prepared heterostructures revealed a good transparency in the visible region. The photocatalytic propertiesof the n-ZnO/p-NiO heterostructures were investigated by measuring the degradation rate of methylene blue. All the samples exhibit a good photocatalytic activity under solar light irradiation. The photocatalytic activity of p-NiO/n-ZnO heterostructureswas strongly correlated with the number of ZnO coatings. The highest photocatalytic activity was obtained at 6 coatings with a degradation rate of methylene blue equal to 98.67% for 4.5h of irradiation.

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Rolling is a very common technique for shaping sheet metal. It aims to reduce the thickness of a metal sample to adapt it to the usual conditions of use in the industry. Nevertheless, this technique is not without modifying the mechanical and microstructural properties of the materials that can influence the mechanical strength of shaped parts. The purpose of the present investigation is to study the changes in microstructures and micro-hardness of Al-Mg-Si alloy with different rolling reduction in thickness and following artificial aging treatments at 175° C . We notice that the micro-hardness increases with the increasing of the deformation level . Reduction in thickness shows a change in microstructure and texture. Characterization methods used in this work is: Optical Microscopy (OM) and, Vickers microhardness.

Nickel oxide (NiO) thin films were successfully deposited by sol-gel dip-coating method on glass substrates. The structural, morphological and optical properties in addition to the photocatalytic activity of the prepared films were investigated. The results show that the films have a polycrystalline NiO cubic structure with dense NiO grains and average optical transmittance in the visible region. The photocatalytic properties of the films were studied through the degradation of methylene blue and 89% of degradation was achieved for 4.5h of solar light irradiation exposure which indicates the capability of NiO photocatalytic activity.