الفهرس | Only 14 pages are availabe for public view |
Abstract in this, the electrodeposition of Zn-Ni-Mn alloy from acidic sulfate electrolyte is studied.the influence of the deposition potential deposition current density, deposition time,pH and manganese sulfate concentration on the deposits compostion , Electrodeposition of zinc coatings on ferrous materials are widely used to provide corrosion protection. Since this protection is not acceptable under severe atmospheric conditions, various alternative methods and materials are being investigated. Various Zn-based alloys are considered such as Zn-Ni and Zn-Mn. Zn-Ni alloy coatings have better mechanical and corrosion resistance properties compared to pure zinc coatings. They have many applications in the electronic industries, automotive industries, electrocatalytic water electrolysis and fasteners. This alloy is also considered as a viable alternative to cadmium for plating aircraft and commercial steel parts. There is a growing interest on the electrodeposition of Zn-Mn alloys because of their superior protective properties and environmental compatibility. Coatings with low manganese content have shown better mechanical properties needed for automotive applications as well as steel protection in different aggressive environments containing activators such as chloride and sulfate ions. Some Zn-Mn alloys exhibit the highest corrosion resistance properties among known Zn alloys. These alloys present a double protective mechanism combining a sacrificial protection and formation of a practically insoluble surface layer. The literatures concerning the ternary alloys are very few in comparison with binary alloys. Consequently, the objective of this work is to collect the properties of both Zn-Ni and Zn-Mn alloys in one alloy via the electrodeposition of Zn-Ni-Mn ternary alloy from acidic sulfate bath. The work also aims to investigate the effect of the deposition xxxiii potential, deposition current density, deposition time, pH and manganese sulfate concentration on the deposits composition, corrosion resistance properties, appearance and surface morphology. X-ray diffraction (XRD) technique is used as one of the experimental evidences for identification of the different deposited alloy phases by comparing them with reference standards from Joint Committee on Powder Diffraction Standard (JCPDS) cards. Scanning electron microscopy (SEM) is used to investigate the morphology (shape and size of the particles making up the deposit), topography (surface features) and crystallography (how the atoms are arranged in the deposit). Energy-dispersive X-ray fluorescence (EDXRF) and atomic absorption spectroscopy (AAS) are used to determine the chemical composition, thickness and cathodic current efficiency of the coatings obtained under different conditions. The interpretation based essentially on the analysis of the cyclic voltammograms, galvanostatic and potentiostatic measurements during electrodeposition process. Linear polarization and anodic linear sweep voltammetry are used to demonstrate the corrosion behavior of the alloys deposited under different conditions. |