Corrosion protection of aluminum foams by cataphoretic deposition of organic coatings

A cataphoretic deposition process is used to realize an organic coating on aluminum foam, in order to increase its durability. Cataphoresis is recognized to ensure high adhesion properties of the coating and good homogeneity, even for surfaces with a complex geometry. The aim of this paper is the optimization of the deposition process and the evaluation of the protection properties of the cataphoretic coating deposited on the aluminum foam. The characteristics of the obtained coatings are assessed by microscopic observation of the thickness dimensions of the protective layer and the presence of defects. The corrosion behavior of the painted foam is evaluated by exposure in acetic acid salt spray chamber and by electrochemical impedance spectroscopy. With higher deposition voltage (300 V), coatings with greater thickness are achieved, containing a minimum presence of defects. These samples also show good corrosion resistance after 1500 h of exposure in acetic salt spray testing cabinet. The relatively low level of the coating defectiveness is confirmed by electrochemical impedance measurements.