الفهرس 
مقدمه الدراسهOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
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.