Corrosion Performance of Aluminum and Stannum as Beverage Packaging

Abstract

The corrosion performance of tinplate (Sn) and aluminum (Al) can as beverage packaging was studied in different acidity of soft drinks available in market. The research objective is to evaluate the acidity of different beverage to corrosion attack. The performance of coating layer provides by manufacturer to enhance corrosion attack was studied as well as corrosion mechanism penetrate on these nonferrous alloy. Electrochemical analysis was used to identify breakdown potential and corrosion damage was analyzed using SEM and energy dispersive spectrometry. Overall, the corrosion rates of stannum are much higher than aluminum for both new and used packaging. From Tafel results, the most corrosion resistant performed by soft drink 1 with pH 2.45 in aluminum packaging followed by manufactured aluminum. Corrosion resistance reduced in tinplate followed by manufactured tinplate. The most corrosion resistance condition was found on the aluminum sheet without manufacturing process that immersed in soft drink A according to its lowest corrosion rate 0.0703mm/yr, followed by manufactured aluminum sheet immersed in soft drink A with second lowest corrosion rate 0.0711mm/yr. All cyclic curves in this test showed that there was no pitting occurred on specimens as the reverse anodic curve was shifted to lower currents and negative hysteresis was produced. From SEM analysis, aluminum was oxidized and oxide film formed on surface to protect the material whereas the tinplate can was corroded and holes produced after electrochemical test. In both corrosion rate measurement and microscope analysis, it was clearly proved that aluminum can had more anti-corrosion properties than tinplate can. There was showed that some leading effect due to can manufacturing to an increasing corrosion rate to the metal beverage cans.