Morpholinium Oligomer as a Novel Vapor Phase Inhibitor on the Corrosion of Mild Steel

• Published in: Corrosion (Houston, Tex.) Tex.), 2005-04, Vol.61 (4), p.392-396
• Main Authors: Zhang, D.-Q., Gao, L.-X., Zhou, G.-D.
• Format: Article
• Language: English
• Subjects: Adsorption; Analytical methods; Animal morphology; Applied sciences; Atmospheric corrosion; Corrosion; Corrosion effects; Corrosion environments; Corrosion inhibitors; Corrosion mechanisms; Corrosion prevention; Current density; Electrochemistry; Exact sciences and technology; Fourier transforms; Inhibitors; Low carbon steels; Metals. Metallurgy; Steel; Vapor phases; Vapors
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1.3279892

ABSTRACTA morpholinium oligomer (MPO) has been developed as a vapor phase inhibitor (VPI) for the temporary protection of mild steel. Its vapor corrosion inhibition property was evaluated under simulated operational conditions. The electrochemical potentiodynamic polarization method was applied to study the effect of MPO on the corrosion inhibition of mild steel in ASTMstimulated atmospheric corrosion water. The results showed that it was a good VPI for steel. It suppressed the cathodic reaction of the steel electrode and depressed the limiting current density of the anodic process. A Fourier transform infrared (FTIR) spectroscopy was used to characterize the adsorption of MPO on the steel surface. The different polar groups of MPO had synergistic adsorption effects.INTRODUCTIONTemporary corrosion protection is designed to prevent the corrosion of metal surfaces of equipment during transport and storage. There are many types of temporary protection methods. A more effective method of corrosion prevention is the use of a vapor phase inhibitor (VPI).1-3 The VPI contains anti-corrosive chemicals, which extend their corrosion-inhibiting properties to a metal surface by volatilization within an enclosed space. The most commonly used VPI are cyclohexyl ammonium carbonate (CHAC) and dicyclohexyl ammonium nitrite (DICHAN). They have been used in industry for several decades. However, the disadvantage of using CHAC and DICHAN is their toxicity. Thus, replacing them with new environmentfriendly inhibitors is desirable. Saurbier, et al., suggested toluylalanine as an effective temporary inhibitor of steel in wet atmosphere.4 Vuorinew reported a series of morpholine Mannich-based derivatives as volatile corrosion inhibitors.5 Polymeric corrosion inhibitors, such as polyacrylic and polyamino-benzoquinone, etc., are widely used in water treatment;6-7 usually they have a lower toxicity than their monomers. Oligomers have a different property of dissolution and volatilization compared with polymers. Thus, they may be developed as VPI where there are environmental concerns. On the other hand, oligomers have more polar groups and bigger molecular size compared with their monomer, so they may have larger coverage on the metal surface and provide better inhibition. The authors have already presented a kind of morpholine oligomer (MPO) as VPI for the temporary protection of box-shaped hatch covers and rudder blades of large ships at HuDong Shipyard (Shanghai, China).8 In the p