engleski

Corrosion characteristic of an aluminium alloy in the H_3PO_4-CO_2 mixture

The Al 6063 alloy examined in this work contains silicon and magnesium capable of forming Mg2Si and iron, which can form an intermetallic second phase (FeAl_3). In order to examine the influence of temperature on the corrosion behaviour of the Al 6063 alloy, examinations were carried out in aerated H_3PO_4 and in H_3PO_4 saturated with CO_2 at temperatures of 20, 30, 40 and 50°C. The following electrochemical methods were applied: determination of dependence of E_OCP on time, recording of anodic and cathodic polarization curves, and cyclic voltammetry. It has been observed that corrosion parameters obtained are strongly temperature dependent. They also depend on CO_2 dissolved in H_3PO_4. CO_2 retards cathodic and anodic reactions at all temperatures, which can be attributed to formation of a kind of mechanical passivity as alloy components react with CO_2.

aluminium; polarization; pitting; corrosion; repasivation

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