Corrosion resistance of carbon steel under an aerobic acidic condition in the presence of borate as corrosion inhibitor

A high-boron concentration solution is commonly used as a buffer system in the study of metal corrosion. However, it is impossible to apply such a high-boron concentration solution in the practical use because of the high-cost and environment problem.

In this study, the authors examined the effect of a low dosage of boric acid and borax mixture as inhibitor to suppress carbon steel corrosion in 1 M HCl solution by weight loss experiment and various electrochemistry methods (potentiodynamic polarization curves, electrochemical impedance spectra and electrochemical noise).

Results showed that the borate mixture exhibited an anodic-type inhibitor characteristic, when the total boron concentration was in the range of 100∼150 mg L⁻¹. The passivation performance derived from the formation of a passive film with and FeBO₃-FeOOH structure, whose integrity and thickness gradually increased with the increasing boron concentration.

Low boron solution could protect carbon steel from the attraction of corrosive ions by forming a passive film with Fe-O-B structure. The findings broaden the application range of borate solution in the industry.