Here, a series of integrated rust conversion agents/ coatings were synthesized by esterification reaction of 3,4,5trihydroxybenzoic acid (GA) and triethanolamine (TE). The structural features, rust conversion ability, and corrosion resistance of the synthesized rust conversion agents/coatings were analyzed using the Fourier transform infrared tests, scanning electron microscopy tests, X-ray diffraction tests, and electrochemical measurements. It was found that when the mass ratio of TE and GA was 2:1, the synthesized rust conversion agent/coating has best rust conversion ability and anti-corrosion performance (i.e., corrosion current density 7.480 × 10 −7 A/cm 2 ). In addition, different from the traditional coatings, the integrated rust conversion coating developed in this study combines the primer and topcoat of traditional coatings into one, which can significantly increase the on-site construction efficiency. Furthermore, a new rust conversion mechanism for the optimized rust conversion agent/coating was proposed. The phenolic hydroxyl functional groups in the rust conversion agent can well chelate with Fe 2+ /Fe 3+ in the original rust layer and then form macromolecular compounds and dense chelating films inside the coating, which tightly wraps rust and also prevents the penetration and diffusion of corrosive medium, making them lose the opportunity to interact with each other.
Purpose
This paper aims to under the laboratory environment, the corrosion behavior of X80 pipeline steel in oilfield injection water in eastern China was studied by immersion test.
Design/methodology/approach
First, the corrosion product film was immersed in oilfield injection water and the effect on the corrosion behavior and the corrosion reaction mechanism were constantly observed during this period. The effect was displayed by potentiodynamic polarization curve and electrochemical impedance spectrums (EIS) measurements. Second, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used to observe and test the corrosion product film immersed in the oilfield water for 30 days.
Findings
The results indicate that the tendency of metal corrosion becomes weaker at an early stage, but strengthened later, which means the corrosion rate is accelerating. Besides, it is indicated by impedance spectroscopy that with the decreasing of the capacitance arc radius, the reaction resistance is reducing in this progress. Meanwhile, the character of Warburg impedance could be found in EIS, which means that the erosional components are more likely to penetrate the product film to reach the matrix. The corrosion product is mainly composed of the inner Fe3O4 layer and outer shell layer, which contains a large number of calcium carbonate granular deposits. It is this corrosion under fouling that produces severe localized corrosion, forming many etch pits on the metal substrate.
Originality/value
The experiment chose the X80 steel, the highest-grade pipeline steel used in China, to conduct the static immersion test in the injection water coming from an oilfield in eastern China. Accordingly, the corrosion mechanism and the effect of corrosion product film on the corrosion of pipeline steel were analyzed and discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.