Corrosion Behavior of Chemical Oxidation Film of Magnesium Alloy in NaCl Solution

Magnesium alloy chemical oxidation is a commonly used conductive anti-corrosion treatment method for aerospace. In order to study the corrosion resistance of its chemical oxide film in the coastal launch site and evaluate the impact of the marine environment on its surface film performance, the corrosion properties of magnesium specimens were studied in 3.5% NaCl solution. The corrosion characteristics with different immersion time were characterized by using scanning electron microscopy, energy spectroscopy and electrochemical methods. The corrosion mechanism was discussed. The results showed that as the immersion time increases, corrosion starts from pitting. The pit spreads to the morphology of multi-pronged extension cracks and then continues to deepen and widen, gradually covers the entire surface of the specimen. The corrosion products are mainly composed of magnesium and oxygen. The electrochemical results show that as the corrosion time increases, the corrosion rate increases from 0h to 12h, which the I_corr increases and the reaction resistance decreases. However, as the corrosion products cover the surface which prevents the corrosion expanding, the V_corr trends to forward shift and reaction resistance increases.