Corrosion inhibition mechanisms

Azole compounds such as benzotriazole, benzimidazole, indazole and imidazoles are efficient anti-corrosion agents for copper and copper-base alloys [1-10]. Many experimental techniques [11-15] have been used to study the corrosion inhibition mechanisms, however, the mechanisms are still not well understood. It is believed that the complex formation between copper and nitrogen atoms would inhibit oxygen adsorption on copper surface [16-20]. 

Classification of corrosion inhibition mechanisms such as interface inhibition, interphase inhibition, intraphase inhibition and precipitation coating (Corrosion 88, Paper 155)... 

R., and Medraj, M. (2014) In-vitro corrosion inhibition mechanism of fluorine-doped hydroxyapatite and brushite coated Mg-Ca alloys for biomedical applications. Ceram. Int, 40 (6), 7971-7982. 

Motta A., M.-P. Gaigeot, Costa D., AIMD evidence of timer sphere adsorption of glydne on a stepped (101) boehmite AlOOH surface. Journal of Physical Chemistry C, 2012. 116 p. 23418-23427. Oguzie, E.E., Y. Li, S.G. Wang, and F.H. Wang, Understanding corrosion inhibition mechanisms-experimental and theoretical approach. RSC Advances, 2011. 1(5) p. 866-873. 

Scheme 19.1 Corrosion inhibition mechanism and adsorption model of ionic liquids on mild steel surface in aqueous sulphuric acid medium [32]...

Fig. 9. Principle of the corrosion inhibiting mechanism of the epoxy-acrylate-silane superprimer containing the zinc phosphate pigments, which protect the metal on-demand [30].

Surface Analytical Study of Corrosion Inhibition Mechanisms. 518... 

On the basis of the corrosion inhibition mechanism, the synergism phenomena can be attributed to different reasons. The cou-lombic interaction between cationic- and anionic-type inhibitors may result in increased adsorption and enhanced inhibition due to the weakening of repulsive forces between adsorbed particles. Complex formation between the inhibitor compounds may result in complex compounds owing to more advantageous adsorption properties than observed for the individual inhibitors. Another way to improve the protective effect of adsorption-type inhibitors is by combination with oxidizers. 

More generic to the paint industry, pigments can also be defined as organic or inorganic fine-particulate solids, substantially insoluble in paint vehicles, that are used to impart certain properties to paint such as color, opacity, corrosion inhibition, mechanical properties and durability. 

For copper corrosion in hot H2SO4, Ross and Berry found that benzotriazole (BTA) inhibits the rate of copper dissolution flow rate and aeration change the inhibitor concentration profile, and a film composed of the cuprous salt of BTA is formed. Other effective inhibitors for copper in H2SO4 include 2,4-dinitrophenyl-hydrazine, benzimidazole, indazole, and quinoline. Various azoles appear to be effective corrosion inhibitors for brass, as well as copper. Finally, Subra-manyan et al. studied the corrosion inhibition mechanisms of the alkaloids quinine (C21H22N2O2) and strychnine (C21H22N2O2). Both compounds inhibit the corrosion of copper, in 1% H2SO4 at 86°F (30°C), relatively well, and both chemisorb and... 

The plethora of data presented in this chapter and in the literature leaves no doubt that corrosion processes and mechanisms for inhibition are complex. Nonetheless, it is well established that conductive polymers can impart significant corrosion protection to selected metals such as steel, aluminum, and copper. Also, a picture is beginning to emerge of the corrosion inhibition mechanisms that rationalizes the observations made on corroding cold steel coated with polyaniline. For this system there are two cases to consider. Case I is where a steel surface exposed to a corrosive environment is completely covered by a coating of doped polyaniline. Case II is a case where a steel surface exposed to a corrosive environment is almost completely covered by a coating of doped polyaniline but also has small areas of bare steel exposed. 

F. Blin, P. Koutsoukos, P. Klepetsianis and M. Forsyth, The corrosion inhibition mechanism of new rare earth cinnamate compounds — Electrochemical studies Electrochimi. Acta, 52, 6212 (2007). 

Seter, M., Hinton, B., and Forsyth, M., Understanding Speciation of Lanthanum 4-Hydroxy Cinnamate and its Impact on the Corrosion Inhibition Mechanism for AS1020 Steel. Journal of the Electrochemical Society, 2012. 159(4) C181-C189. 

Characterization of rare earth corrosion inhibition mechanisms... 

Given some basic information about the corrosion inhibition mechanisms of chromates, many studies have been conducted for chromate replacements. For effective replacement of hexavalent Cr, however, an inhibitor has to inhibit the oxygen reduction reaction as well as anodic dissolution/pitting, and several studies indicate that hybrid formulations seem to be the best way to do just that. Typically, in these hybrid formulations an organic oxygen reduction reaction inhibitor is included with environmentally benign anodic inhibiting anions. 

Phosphonates and their derivatives have also featured in quantum chemistry studies during 2011. A DFT study at the B3LYP/6-31G level was performed for the corrosion inhibition mechanism of methylene phosphonic acid, and DFT calculations at the B3LYP/6-311-M-G level have supported the vibrational (IR, Raman and SERS) spectroscopy characterization studies of L-leucine phosphonate analogues, and also L-valine phosphonate dipeptides. ... 

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