engleski

Corrosion Protection of Patinated Bronze by Azole Type Inhibitors

Bronzes have been widely used to produce sculptures and other objects of art. These artistic bronze objects are usually found covered by a layer of patina either formed spontaneously during the years of exposure or artificially formed in various solutions of inorganic salts. Acid rain that forms due to the presence of polluting gases may cause extensive damage on the bronze objects and patina layer. The SO2 and NOx are the main pollutants in urban atmosphere due to the industrial activity and the emission by automotive vehicles. The aim of this study was to investigate the possibility of protection of patinated bronze by different azole type inhibitors. For many years benzotriazole was used for protection of copper alloys but due to its toxicity it has to be replaced by some less toxic compound. In this work inhibiting efficiency of benzotriazole as a reference and an environment friendly imidazole based compound was studied. Studies were performed in the solution that simulates acid rain in polluted urban environment. Examinations were performed by the means of electrochemical methods (polarization measurements and electrochemical impedance spectroscopy) on three types of patinated bronze that represent both contemporary and historical artistic bronze. Bronze patina was obtained by chemical (representing blue-green patina obtained in artistic workshops) or electrochemical patination (simulating spontaneously formed patina). The two inhibitors were applied to patinated samples as ethanol solution, as ethyl acetate solution with an ethyl metacrylate/methyl methacrylate copolymer. The results reveal the proper application technique for each inhibitor. The efficiency of each studied corrosion inhibitor is compared as well as the mechanism of their inhibiting action. By EIS measurements stability of applied protection was followed in time. The results will offer a new knowledge in a patinated bronze protection

corrosion inhibitor; bronze patina; environment friendly

nije evidentirano