Study of the anticorrosive properties of quebracho colorado extract and its use in a primer for aluminum1050

Tannins have been used to replace chromate in wash-primers as a temporary (in transit) protection for metals. In the present work, the anticorrosive properties of quebracho colorado tannins were tested in water solution and in wash primers to protect aluminum alloy 1050. Polarization curves (linear and Tafel) and corrosion potential measurements were done on the alloy in contact with different concentrations of the tannin. A tannin wash primer was prepared and coated panels were tested in 100% humidity chamber (ASTM D 2247) and by electrochemical techniques (linear polarization curves, corrosion potentials and ionic resistances). Chromate and talc primers as well as no-coated aluminum alloy were also tested, as control, to compare the results.