A Synergistic Effect between Stearic Acid and (+)-α-Tocopherol as a Green Inhibitor on Ferritic Stainless Steel Corrosion Inhibition in 3.0% NaCl Solution

Abstract

The synergistic inhibitory effect of stearic acid and (+)-α-tocopherol (E307) as a green inhibitor within a highly hydrophobic layer on the corrosion of low-carbon ferritic stainless steels was investigated in 3.0 wt% NaCl solution at 25 °C, focusing on long-term immersion tests. For a broader characterisation of the surface properties, especially the modified surfaces, of the samples used, the following methods were chosen: SEM was used to investigate the surface morphologies, the water contact angle to examine the wettability, while the corrosion resistance was investigated by potentiodynamic measurements and electrochemical impedance spectroscopy. The inhibition efficiency for modified ferritic stainless steel surfaces reached more than 99% after 1 h of immersion and remained the same after 5 days immersion testing when the surfaces were modified with (SA + 2.0 wt% E307) and more than 97% with (SA + 0.5 wt% E307) under the same test conditions.