Effect of temperature and concentration on the passive film properties of a duplex stainless steel in LiBr solutions

摘要

Lithium Bromide (LiBr) is one of the most widely used absorbents in refrigeration technology. However, the operating conditions in the absorption machines can generate serious corrosion problems in the structural materials. Duplex stainless steel could be employed in absorption machines due to their good mechanical properties and corrosion resistance. Cyclic potentiodynamic curves and electrochemical impedance measurements were carried out with the as-received an sensitised (825°C, 1h) Alloy 900 in LiBr solutions at two concentrations (400 g/l and 992 g/l) and at different temperatures (25, 35, 45 and 55°C). According to the results, the polarisation resistance decreases with the solution temperature and the LiBr concentration. Additionally, the sensitisation process has a negative effect in the polarisation resistance; these results are in agreement with those observed in the cyclic potentiodynamic curves.