Elaboration and investigation of corrosion inhibition by bismuth glasses for mild steel in 1.0 M HCl solution

A new corrosion inhibitor based on bismuth-containing glass with the composition of (1-x-y) Bi2O3+ yB2O3 + x P2O5 (avec 0 ≤ x ≤ 0,9) was developed. Its effectiveness in preventing steel corrosion in 1 M hydrochloric acid (HCl) solution was evaluated using various electrochemical techniques including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The experimental results showed that the glassy compounds provided significant corrosion protection. However, their inhibitory effect decreased with increasing temperature. The polarization curves indicated that these compounds acted as mixed-type inhibitors. In particular, the inhibitory effect increased with decreasing inhibitor concentration and the highest inhibitory effect of 92.0% was achieved for compound P1. Important kinetic parameters including activation energy, activation enthalpy and activation entropy were determined and analyzed. Thermodynamic analysis confirmed that a protective film was formed on the steel surface in the presence of the inhibitor.