الفهرس 
Improvement of the surface properties of the aluminum alloys used in the military applications
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Abstract
The corrosion behavior and characterization properties of the hard anodizing coating layer, formed on aluminum alloys in sulphuric acid electrolyte containing sodium lignin sulphonate, and the corrosion behavior and characterization properties of a novel Ni-P coating on anodized aluminum alloys was investigated by using salt spray procedure and Potentiodynamic polarization technique, in artificial seawater.The anodic process and the Ni-P layer on anodized coating procedure were performed on different groups of aluminum alloys as Al2014, Al6061and Al7075, which are used in military industries. The results showed that the corrosion resistance and the coating layer are influenced by the type of the alloy and the coating conditions such as current density, acid concentration, temperature of electrolyte and time of duration. Moreover, changes in film thickness, coating weight and hardness of aluminum alloys have been studied and the obtained results were compared and analyzed. Adsorption of sodium lignin sulphonate on oxide surface has been confirmed by Fourier transform infrared spectroscopy (FTIR). The phenolic and carboxylic groups in lignin inhibitor are responsible for forming a complex on the metal oxide surface that improves the corrosion resistance. The hardness order of Aluminum alloys: Al7075 > Al2014 > Al6061, owing to copper presence in Al7075 and Al2014 that increases well the hardness.While the hardness order of anodized layer and electroplated Ni-P coating on anodized Aluminum alloys are: Al7075 > Al6061 > Al2014.The abrasion resistance of Aluminum alloys is: Al2014 > Al7075 > Al6061 while the abrasion resistance of anodized Aluminum alloys and electroplated Ni-P coating on anodized Aluminum alloys are: Al7075 > Al6061 > Al2014.The corrosion resistance and the corrosion rate of the surface modified alloys were found to be dependent on the alloying element (copper in the alloying element). The corrosion rate of Al7075 and Al6061 were decreased by about one order of magnitude, whereas the corrosion rate of Al2014 was increased by about the same order of magnitude. This means that the morphology of the surface and the alloying elements affect well the Ni{u2013}P coatings