Study on the Synergistic Corrosion Inhibition Effect between Sodium Silicate and Triethanolamine for 45 Steel Corrosion in 3.5% NaCl solution

Silicate is an environment-friendly corrosion inhibitor with abundant resources and low cost. Given the shortcomings of protective films formed by silicate corrosion inhibitors and their short protection duration, the formation of a composite corrosion inhibitor comprising sodium silicate as the base solution and triethanolamine was investigated using 45 steel as the substrate. Humidity and temperature accelerated corrosion testing, scanning electron microscopy and laser confocal microscopy, electrochemical testing and molecular simulation were used to determine the effect of triethanolamine on the corrosion inhibition performance of sodium silicate, revealing a synergistic adsorption phenomenon. Molecular simulation verified the synergistic corrosion inhibitory mechanism of sodium silicate and triethanolamine. The results showed that the presence of triethanolamine could improve the corrosion inhibition performance of sodium silicate due to the synergistic adsorption effect of triethanolamine and sodium silicate. Since there was also a competitive adsorption relationship between the two components, when the amount of triethanolamine exceeded 3 g.L-1 the corrosion inhibition effect of the composite corrosion inhibitor began to decrease. Therefore, the corrosion inhibitor with sodium silicate at 10 g.L-1 and triethanolamine at 3 g.L-1 had the best synergistic corrosion inhibitory effect.