engleski

Electrochemical and spectroscopic study of artificially obtained sulphide patina

Copper and its alloys exposed to atmospheric conditions form a thin layer of corrosion products called patina. Patina protects the base metal from further corrosion. Color and properties of patina depend on the alloy composition, metallurgical features and type of corrosive environment, i.e. presence of aggressive ions (SO2, CO2, NO2). Patination is slow process that lasts up to 100 years in less corrosive environment. Therefore, artificially patination is used instead. In Croatia, artificial patination using K2Sn is the most familiar method for obtaining black sulphide patina. The application of artificial patina has become a very common method for pretreatment of bronze artefacts exposed to outdoor atmosphere. In this work artificially obtained sulphide patina on copper and several bronzes (CuSn6, CuSn12, RG7) is exposed to various conditions as accelerated aging in form of continuous immersion in simulated rainwater or alternating wet/dry cycles. Electrochemical properties are examined by using electrochemical impedance spectroscopy (EIS). Composition and morphology of patina are examined by FTIR spectroscopy, SEM/EDX and optical microscopy.

artificial patina ; bronze ; electrochemical methods

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