Corrosion protection properties of hydroxamic acid self-assembled monolayer on carbon steel

Self assembled monolayers (SAMs) of hydroxamic acids CH3(CH2)nCONHOH with different alkyl length were formed on the carbon steel electrode surface. The corrosion protection properties of the monolayers were examined and characterized by electrochemical polarization curves, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy (XPS) and contact angle measurements. XPS results showed that the hydroxamic acid molecules adsorbed on the carbon steel surface, and the contact angle values on the modified surface supported the formation of hydrophobic hydroxamic acid SAMs. The results of electrochemical studies showed that the values of the corrosion potential shift towards the positive direction, and anodic currents of the carbon steel dissolution significantly decreases, indicating that hydroxamic acids are anodic inhibitors. However, the chain length and assembling time influence the protection efficiency.