Estudo do poder de proteção dos ácidos cítrico e oxálico em folhas de estanho

Abstract

The corrosion of Tin generates great economic loss mainly in the electronics industry and facilitates metal intake through food packaging, which may pose risks to human health. In this context, has been trying new environmentally friendly organic inhibitors, studying the protection capacity of citric acid and oxalic acid, through immersion tests, obtaining the corrosion rate through the gravimetric methods. Different concentrations (10-3, 10-4 and 10-5 mol.L-1) of these potential inhibitors were analyzed in relation to white, without inhibitor, in aggressive environment with different pH's: 3.0, 4.0, 5.0 and 6.0. The loss of mass Tin parts makes it possible to analyze the behavior of corrosion speed and behavior of corrosion rate with respect to time. Speed curves indicated that there is deposition of corrosion products on the metal surface independent of the concentration of inhibitors or the pH of the environment. The behavior of Tin corrosion rates reported that acids assist in deposition of Tin oxide and Tin hydroxides formed by corrosion, independent of the concentration of the inhibitor, facilitating the formation of the film over the surface, preventing metal interaction with the kind of aggressive, consequently decreasing corrosion rates. In this way, the acids, citric and oxalic, presented be efficient corrosion inhibitors of the Tin.