Effects of surface preparation and performance of chromate conversion coating on final coating adhesion, mechanical and corrosion properties on 5083 Al alloy

Coating has an expended usage in different industries in order to prevent the contact with the corrosive environment. Beside, coating’s quality is connected extensively to the position of the surface under the layer. In this essay different ways of preparation of the surface have been studied and compared before the applying the coating which includes the mechanical preparation (such as grinding, brushing and blasting) and also implementation of the conversion coating as a mid-cover. Organic coating of epoxy was applied after the preparation of the samples of aluminum alloy 5083 and also corrosion resistance, coating adhesion, mechanical strength, and the use of color in different samples were compared. Polarization method was used to compare the strength to corrosion in order to study the characterization of conversion coating and to obtain an optimized situation for applying it. By studying experimented samples, it was concluded that the implementation of mechanical preparation has a negative effect on the characterization of mechanical components. If roughening the surface is done consumedly to increase the effective area, it causes corrosion properties. On the other hand the consumption of color can be increased to 3 times more than normal rate, so in comparison wet blast method has more disadvantages. Applying conversion coating as a mid-layer has improved considerably the corrosion properties, and also in this method the consumption of color is equal to not prepared samples. This method has a low rate of cost and relatively it has fast and simple operations. This method had not been already used in coloring and it is a new method for improving the coating’s properties on aluminum surfaces.