Shuan Liu

1. Marine biofouling, the accumulation of marine organisms such as algae, barnacles, and mollusks on submerged surfaces, is a pervasive and costly issue in global maritime industries.[1–3] It signi...

A graphene modified epoxy surface tolerant coating was prepared, and the corrosion performance and rust conversion mechanism of the prepared composite coating on rusty carbon steel substrate was investigated. Scanning electron microscope (SEM), X-ray powder diffractometer (XRD), and infrared (IR) spectrum were used to confirmed the iron rust conversion performance by the reaction of phytic acid and rust. electrochemical impedance spectroscopy (EIS), polarization curve, and salt spray test were used to evaluate the corrosion resistance of low surface treatment coatings. Results indicated most of the rust were dissolved and transformed with the reaction of phytic acid and rust on the rusty carbon steel; graphene could effectively improve the compactness and protective performance of the epoxy surface tolerant coating.

Galvanized steel has excellent corrosion resistance in atmospheric and soil corrosive environments, because a dense and passive zinc oxide film, formed on the surface could effectively inhibit the corrosion of the Fe substrate. The galvanized steel wire has been widely embedded in vegetation‐growing concrete for reinforcement and showed good corrosion resistance and strengthening performance. However, in the marine area, the corrosion rate of galvanized steel is accelerated, and the galvanized steel wire will be failed in vegetation‐growing concrete in a short time. This study has been carried out with a view to analyze the corrosion performance and corrosion mechanism of galvanized steel wire embedded in vegetation‐growing concrete in the marine environment. EIS and Tafel curves were employed to study the corrosion performance of galvanized steel under different chloride concentrations and temperatures in vegetation‐growing concrete lixivium. Results showed that the corrosion rate of galvanized steel increased with the increase of chloride concentration and the temperature in vegetation‐growing concrete lixivium.

In previous work, the corrosion performance and anti‐corrosion mechanism of galvanized steel wire embedded in vegetation‐growing concrete under marine environment was highlighted. In this work, a graphene‐modified epoxy coating was developed and applied to the protection of galvanized steel in vegetation‐growing concrete under a marine environment. The effect of dispersed graphene on the anticorrosion performance of the epoxy coatings was evaluated. The composite coatings displayed outstanding barrier properties against H₂O molecules compared to the pure epoxy coating. Salt spray test results revealed superior corrosion resistance offered by the prepared graphene‐modified epoxy coating on galvanized steel.

A phytic acid‐based surface tolerant epoxy coating was prepared, and the effect of phytic acid on the corrosion resistance of the composite coating on rusty carbon steel substrate was investigated. The results showed that the low‐frequency impedance modulus of the composite coating on rusty carbon steel could reached 10⁸ Ω·cm² order of magnitude after immersing for 480 h in 3.5 wt% NaCl solution. Compared with pure epoxy coating, the phytic acid‐based surface tolerant epoxy coating on the rusty substrate exhibited better corrosion resistance even if with some artificial defects in the composite coating. The protective performance of the composite coating mainly came from the formation of a stable iron phytate chelate in the reaction of phytic acid and rust. For the rusty carbon steel, the original Fe³⁺ on its surface was also transformed by phytic acid penetrating to the interface between the coating and the substrate. Therefore, a dense film was formed with the reaction of phytic acid and rust on the substrates, and the dense film became a part of the whole paint film, which could improve the corrosion resistance of the surface tolerant coating.

Given their outstanding versatile properties, multilayered anticorrosion coatings have drawn great interest from researchers in the academic and engineering fields. However, the application of multilayered coatings is restricted by some limitations such as low interlayer compatibilities, the harsh preparation process, etc. This work introduced a composite film fabricated on a 2A12 aluminum alloy surface, including an anodic oxide film, a sol–gel film, and a layer-by-layer (LBL) self-assembling film from bottom to top. The microstructure and elemental characterization indicated that the finish of the coating with the LBL film resulted in a closely connected multilayered coating with a smoother surface. The anticorrosion performance was systematically evaluated in the simulated corrosive medium and neutral salt spray environment. The integrated coating with the LBL film presented an excellent anticorrosion ability with system impedance over 10⁸ Ω·cm² and a self-corrosion current density two orders of magnitude lower than that of the other coatings. After the acceleration test in a salt spray environment, the multilayered coatings could still show a good protective performance with almost no cracks and no penetration of chloride ions. It is believed that the as-constructed multilayered coating with high corrosive properties and a fine surface state will have promising applications in the field of anticorrosion engineering.

In this work, a water-soluble host–guest complex containing carboxymethylated beta-cyclodextrin (CM-β-CD) and an aniline trimer (AT) was synthesized. The application of AT–CM-β-CD as an inhibitor for alleviating the corrosion of Q235 carbon steel in 1 M HCl solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that the inhibition efficiency was significantly increased in the presence of AT–CM-β-CD, and the inhibition efficiency was up to 99.2% when the concentration of AT–CM-β-CD was 250 mg L⁻¹. Field emission scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM) confirmed that the corrosion inhibitor had excellent corrosion inhibition effects due to the formation of an adsorption film on the surface of Q235 carbon steel. According to the data extracted from the Langmuir adsorption model, AT–CM-β-CD absorption involves both physisorption and chemisorption.

Correction for ‘Effect of graphene oxide on anticorrosion performance of polyelectrolyte multilayer for 2A12 aluminum alloy substrates’ by Xia Zhao et al., RSC Adv., 2017, 7, 33764–33774.

Corrosion of aluminum alloys (Al alloys) has been a ubiquitous problem, and this seriously restricts its range of applications.

Corrosion Resistance and Tribological Properties of Epoxy Coatings Reinforced with Well-Dispersed Graphene | InTechOpen, Published on: 2016-10-05. Authors: Liu Shuan