咪唑啉衍生物与硫脲对X65钢在惰性沉积物 垢下腐蚀的缓蚀机理研究

To solve the problem of under-deposit corrosion of X65 steel in CO₂-saturated oilfield-produced water, the corrosion inhibition performance of alkyl imidazolines (IM), thiourea (TU) and their compound corrosion inhibitors (TU/IM) on X65 steel under SiO₂and CaCO₃inert deposits was investigated using electrochemical analysis and surface analysis. The results show that the corrosion inhibition efficiency η of the three inhibitors may be ranked as η (TU/IM) > η (TU) > η (IM). When adopting IM as inhibitor, the formation of a continuous protective corrosion inhibitor film is difficulty on the steel surface under the two type scales of inert deposits, while the corrosion of metal under the SiO₂deposits is accelerated, thus IM is poor in corrosion inhibition performance. For TU as a mixed-type inhibitor, both the cathodic and anodic reactions are suppressed, which may be due to that the S atoms of TU tend to coordinate with the empty d-orbitals of Fe atoms, thereby generate coordination chemical bonds, resulting in an electrons rich band in this region, which in turn enhance the stability and protection ability of the formed inhibitor film. Whereas, the TU/IM combination inhibitor demonstrate excellent synergistic inhibition effect, which may be ascribed to that TU initially formed a primary adsorption film on the steel through its superior diffusivity and adsorption capacity, while IM subsequently contributed hydrophobic chains to establish a secondary adsorption film, this dual-layered structure significantly enhances the corrosion inhibition effectiveness.