Cyclic voltammetric studies of carbon steel corrosion in chloride-formation water solution and effect of some inorganic salts

AbstractThe influence of sulfide, sulfate and bicarbonate anions on the pitting corrosion behavior of carbon steel in formation water containing chloride ions were analyzed by means of cyclic voltammetry technique and complemented by X-ray diffraction (XRD) investigation. The anodic response exhibits a well-defined anodic peak A, followed by a passive region. A pronounced increase in the anodic current density is observed in the passive region at pitting potential (Epit). On the other hand, the cathodic sweep shows two cathodic peaks CI and CII. The data show that the presence of chloride ions causes pitting corrosion of carbon steel in formation water. It was found that both the pitting potential Epit and the repassivation potential (Epro) decreased with increase in Cl− ions concentration. Data clearly show that the presence of Na2S with 0.3M of chloride ions has a strong accelerating effect on the active dissolution and pitting corrosion of carbon steel in formation water, while the presence of Na2SO4 and NaHCO3 with chloride ions has an inhibiting effect on the active dissolution and pitting corrosion

Novel epoxy/metal phthalocyanines nanocomposite coatings for corrosion protection of carbon steel

In this study, epoxy/metal phthalocyanines nanocomposites (NiPc/Epoxy, CuPc/Epoxy, and ZnPc/Epoxy) are employed to protect carbon steel corrosion in 3.5% NaCl solution. The corrosion performances of the nanocomposites coatings were evaluated by using electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) and scanning electron microscopy (SEM) measurements. The mechanical property of the coating system was investigated using nanoindentation technique. The results indicated that the incorporation of metal phthalocyanines pigments into epoxy resin coating significantly enhances the corrosion resistance as well as the hardness of epoxy coatings.Metal phthalocyanines pigments are able to cure the defect in epoxy resin and prevent the diffusion of corrosive electrolyte to carbon steel substrate. It was found that NiPc/Epoxy nanocomposite gave the best protection performance than others

Influence of newly synthesized titanium phosphates on the corrosion protection properties of alkyd coating

This study reports the effect of three new titanium phosphates Li0.5M0.25Ti2(PO4)3 (where M = Mn, Co and Ni) on the protective properties of alkyd resin films applied on carbon steel substrate in 3.5% sodium chloride solution. The performance of the coatings was evaluated by electrochemical impedance spectroscopy, oxygen and water permeability and pull-off adhesion measurements. It was found that titanium phosphates improve the corrosion resistance as well as the adhesion strength of alkyd resin coatings. The incorporation of titanium phosphates into the alkyd resin coating significantly enhances the pore resistance of the alkyd resin and decreases the coating capacitance. Lower water and oxygen permeability were observed for alkyd resin containing titanium phosphates, confirming formation of a protective layer on the surface. The order of anticorrosion performance of the three coatings was as follows: Li0.5Mn0.25Ti2(PO4)3 > Li0.5Co0.25Ti2(PO4)3 > Li0.5Ni0.25Ti2(PO4)3