engleski

Bronze Protection in Sulphate/Carbonate and Nitrate/Carbonate Media by a Nontoxic Corrosion Inhibitor

The aim of this work was to investigate corrosion of bronze in media that simulate polluted atmosphere and acid rain. The possibility of bronze protection with an environment friendly corrosion inhibitor: 1-phenyl-4-methylimidazole was studied as well. The research was carried out in the electrolytes 0.2 g dm- 3 NaHCO3 + 0.2 g dm-3 Na2SO4 and in 0.2 g dm-3 NaHCO3 + 0.2 g dm-3 NaNO3 at pH 3. In this way the influence of both pollutants characteristic for urban atmosphere (SO2 and NOx) was separately examined. Measurements were performed by the means of electrochemical methods: Tafel extrapolation method, linear polarization method and electrochemical impedance spectroscopy. The results of this study have shown that 1-phenyl-4-methylimidazole considerably reduces corrosion rate of bronze in carbonate sulphate medium (84%). All three methods have shown a high efficiency of inhibitor and it was determined that the maximal corrosion inhibition efficiency is obtained at concentration of 5*10-3 mol dm- 3. 1- phenyl-4-methylimidazole has shown lower efficiency of bronze protection in nitrate /carbonate medium than in sulphate/carbonate medium. The results show that the maximal corrosion inhibition efficiency (75%) in nitrate /carbonate medium can be obtained at concentration of 10-3 mol dm-3. The adsorption free energy determined in sulphate/carbonate (-35 kJ mol-1) and nitrate/carbonate solutions (-30 kJ mol-1) reveals a physical adsorption of the inhibitor on the bronze surface.

Corrosion protection; Inhibitors; EIS; Bronze; Atmospheric corrosion

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