Copper Plating Corrosion Study in Certain Environments

Copper plating was performed on nickel substrate by means of the potentiostatic electrodeposition method from a sulphate electrolyte solution. The copper coatings morphology was studied by means of the optical and electronic scanning microscopy techniques. The uniform electrodeposited films have a thickness of about 15 µm measured in cross-section. The corrosion behaviours of nickel substrate and copper films in different corrosive environments were studied. The corrosion study was performed by means of the linear polarisation method in four acid environments: 0.5 M H2SO4, HCl, HNO3 and glacial CH3COOH. From the recorded Tafel curves it was possible to obtain some information about the corrosion rate and the polarization resistance. In order to confirm these results, the gravimetric parameter was calculated by means of the “mass loss” method. By means of the X-ray diffraction analysis, the crystallographic structure of the specimens before and after corrosion was revealed. By means of the spectrophotometer device, the optical properties of the specimens were analysed

Preparation and Characterisation of Alumina Template Obtained by OneStep Anodization Method

The goal of this study was to obtain an alumina template (AAO) by one-step anodization method and to evaluate its optical properties correlated with the annealing temperature. AAO was obtained from two different media: sulphuric acid (1.5 M H2SO4) and oxalic acid (0.4 M H2C2O4) at a potential of 15 V and 40 V, respectively. AAO morphology and chemical composition had been investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The average pore diameters such as 20 nm for AAO obtained from H2SO4 and 40 nm from H2C2O4 were measured. The crystalline structures of AAO samples annealed at three different temperatures of 150 ºC, 300 ºC and 350 ºC were studied by Xray diffractometry (XRD). The effect of annealing temperature on the optical properties of AAO was studied by UV-VIS spectrophotometry

Electrophoretic synthesis and characterization ofbioactive HAp/TiO2 thin films coated on stainless steel

The aim of this study was to synthesize titanium dioxide (TiO2) thin films coated on 316L stainless steel (316L SS) and to characterize hydroxyapatite (HAp) growing onto TiO2 layer coated on the metallic substrate. These films were obtained by the electrophoretic synthesis (EPS) method using an acidic electrolyte containing H2SO4 and TiO2 nanoparticles. The growth of HAp on TiO2 thin films was achieved by immersion in simulated body fluid (SBF) during different periods of time in order to evaluate the bioactivity of structure in vitro study. The obtained coatings were characterized by XRD, SEM, AFM and EDX measurements. The XRD results reveal a crystalline phase (anatase) of TiO2 nanoparticles. The presence of TiO2 nanoparticles in the bath led to the preferential orientation of TiO2 crystallites after [101] crystallographic direction. During the coating EPS process, the presence of TiO2 provides more nucleation sites which are favourable to the adherence of nanoparticles on the metallic substrate. The surface morphology observed by SEM analysis showed that TiO2 nanocrystals were attached on metallic surface. The appearance of the surface indicates porous structure and island-like cracked morphology with polygonal shapes. The roughness of the coating is in good agreement with standards for biomaterials which is proved by AFM measurements. The EDX spectra also confirm the presence of the Ca2+ and PO4 3- ions in the structure obtained by EPS method

Electrocodeposition of Ag/TiO2 nanocomposite coatings in cyanide free electrolytes

Synthesis and characterisation of nanocomposite coatings consisting of Ag doped TiO2 nanocrystals at different concentrations have been carried out. Composites were obtained by electrochemical deposition using a slightly alkaline cyanide free electrolyte containing AgNO3 as Ag precursors. Morphology and crystalline structure of the Ag/TiO2 hybrid materials with up to 8?5 vol.-%TiO2 were compared with those of pure Ag coatings. The presence of TiO2 nanoparticles in the bath led to an increase in the degree of orientation of crystallites on [111] and [311] crystallographic directions. During the electrodeposition, the presence of TiO2 particles at the electrode/electrolyte interface retards the crystal growth, and hence, the composites possess smaller grain sizes. The surface morphology observations show that TiO2 nanocrystals were attached within the metallic matrix surface, and the appearance of the surface indicates a porous structure with different geometrically shaped grains; this is also confirmed by atomic force microscopy measurements

Globalisation and International Students: Remodelling Micro-international Aspects for the Entrepreneurial University

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