The corrosion inhibition mechanism of surfactants is mainly to form an adsorption film on the metal surface. The hydrophilic group is adsorbed on the metal surface and inhibits corrosion by geometric covering effect, while the hydrophobic group can also repel the corrosive medium. Due to the different properties of the hydrophilic group, the surfactant undergoes physical adsorption or chemical adsorption with the metal surface, and its adsorption rules are also different. Polyvinylpyrrolidone (PVP) is a non-ionic surfactant that is non-toxic, harmless, and environmentally friendly. It can be used as a green and environmentally friendly corrosion inhibitor for metal corrosion protection. By combining electrochemical testing technology with surface analysis, its corrosion inhibition performance and mechanism for steel bars in simulated concrete pore fluid containing Cl were studied. SEM photos of the steel bar surface after immersion in the simulated liquid for 3 hours under surface morphology and composition analysis. It can be seen that before immersion, the surface of the polished steel bar is relatively smooth and has no obvious defects. After immersion in the simulated liquid, local corrosion occurred on the surface of the steel bar, showing obvious corrosion pits. This is because Cl destroyed the passivation film on the surface of the steel bar, causing pitting corrosion. It can be seen that when the simulated liquid contains 25 mg/LPVP, the surface of the steel bar remains flat and smooth, and no corrosion occurs, which is similar to the morphology before immersion, indicating that the corrosion inhibitor forms an effective protective film on the surface of the steel bar, which plays a good protective role on the steel bar. The SEM characterization results further verify the above electrochemical test results.
