The influence of phosphonic acid pretreatment on the bronze corrosion protection by waterborne coating

This work examines the possibility of acrylic waterborne coating application in the protection of bronze cultural heritage. In order to enhance the coating protective properties, the surface pretreatment with long-chain phosphonic acid is investigated. Studies are conducted on bronze, either bare or covered by two types of patina, by using polarization measurements and electrochemical impedance spectroscopy during 3 weeks of continuous immersion in simulated urban acid rain solution. The role of 12-aminododecylphosphonic acid as corrosion inhibitor and adhesion promoter is studied. The results obtained within this research show that the corrosion protection by the waterborne coating increases in time in all cases and it is enhanced by the phosphonic acid pretreatment. The greatest impact of studied pretreatment on the overall corrosion protection level is observed on bare bronze substrate.