Effects of Na 3 PW 12 O 40 on the corrosion behavior of carbon steel in 55 %LiBr solution

Electrochemical technologies, chemical immersion tests and surface detection technologies were adopted to study the inhibition performance of Na 3 PW 12 O 40 inhibitor on carbon steel in 55 % LiBr + 0.07 mol/L LiOH solution, and the inhibition mechanism was discussed. Results indicated that Na 3 PW 12 O 40 inhibitor caused the decrease of both anodic and cathodic polarization current density and a widening of the passive potential region. It behaved as a mixed inhibitor. When the concentration of Na 3 PW 12 O 40 in 55 % LiBr + 0.07 mol/L LiOH solution was 300 mg/L, excellent inhibition performance on carbon steel was obtained. When the solution temperature were 145°C, 160°C, 180°C and 200°C, respectively, the corrosion rates of carbon steel were 13.07 μm/y, 17.74 μm/y, 24.55 μm/y and 73.52 μm/y accordingly. Na 3 PW 12 O 40 inhibitor exhibited an excellent inhibition performance at high temperature. Na 3 PW 12 O 40 is a strong oxidant. Fe was oxidized to Fe 2 O 3 and itself was deoxidized to heteropoly blue. By this mechanism, an integrate compact passive film mainly comprising Fe 2 O 3 may be formed on the carbon steel surface, and the corrosion of carbon steel in 55 % LiBr solution may be retarded by this passive film.