engleski

The artificially patinated bronze behaviour in various corrosion conditions

Bronze objects found outdoors are usually covered by patina which has either formed during the exposure to outdoor atmosphere -natural patina or has been applied in artistic foundries or by restaurateurs. Application of brown sulphide patina by using K2Sx solution is the most common method of artificial patination used in Croatia. Although such patina is commonly protected by application of wax, the protection level vanishes in time and the bronze is exposed corrosive attack of outdoor atmosphere. This results in gradual formation of new patina layer. In urban and industrial environments this layer consists mostly of sulphate compounds. In this work brown patinated bronze is exposed to various aging conditions like outdoor exposure, or accelerated aging in form of continuous immersion in simulated rainwater or alternating wet/dry cycles. Changes in corrosion properties of patinated bronze are examined by using electrochemical impedance spectroscopy (EIS) while the composition and morphology of patina is examined by FTIR spectroscopy and SEM/EDX. Obtained results are compared to those obtained by EIS and spectroscopic measurements conducted on bronze sculpture exposed to urban atmosphere for 20 years.

bronze ; artificial patina ; atmospheric corrosion ; electrochemical impedance spectroscopy

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