Corrosion of oil and gas pipelines significantly reduces the service life of the pipelines, thus increasing costs, and more seriously, it can cause catastrophic environmental accidents. More recently, the exploitation of oil in ultra-deep seawater fields is facing new technological challenges in material selection owing to the extreme production conditions. Thus, the development of organic coatings as protective layers for steel pipelines is of crucial importance against highly corrosive environments. In this work, fusion bonded epoxy (FBE) coatings were deposited onto chemically functionalized carbon steel surfaces with organosilanes to investigate the potential applications in protection against corrosion and degradation in harsh marine environments. Carbon-steel API 5L X42 (American Petroleum Institute Standard grade) was chemically functionalized with two organosilanes, 3-APTES [(3-Aminopropyl)triethoxysilane], and 3-GPTMS [(3-Glycidyloxypropyl)trimethoxysilane], followed by the deposition of FBE composite coatings. The systems were extensively characterized with respect to each component as well as the steel-coating interface. The contact angle measurements and Fourier transform infrared spectroscopy (FTIR) results clearly indicated that the steel surface was effectively modified by the functional amine and glycidyl silane groups, leading to the formation of interfacial covalent bonds with increased hydrophobicity compared to bare steel surfaces. In addition, the morphological and chemical characterizations of FBE by scanning electron microscopy, atomic force microscopy, X-ray diffraction, and FTIR showed that it is composed of an epoxy-based organic matrix of bisphenol-A diglycidyl ether (DGEBA) reinforced with uniformly dispersed inorganic phases of calcium silicates and TiO 2 particles. Moreover, the chemical functionalization of the steel surfaces with amino and glycidyl silanes significantly altered the interfacial forces with the FBE coatings, resulting in higher adhesion strength for 3-APTES-modified steel compared to 3-GPTMS-steel; however, both mostly showed cohesive rupture mode in the FBE component.

The performance of fusion-bonded epoxy coatings can be improved through advanced composite coatings reinforced with nanomaterials. Hence, in this study a novel organic-inorganic nanocomposite finish was designed, synthesized, and characterized, achieved by adding γ-aminopropyltriethoxysilane modified silica nanoparticles produced via sol-gel process in epoxy-based powder. After the curing process of the coating reinforced with nanoparticles, the formation of a homogenous novel nanocomposite with the development of interfacial reactions between organic-inorganic and inorganic-inorganic components was observed. These hybrid nanostructures produced better integration between nanoparticles and epoxy matrix and improved mechanical properties that are expected to enhance the overall performance of the system against underwater corrosion.

This study compares the corrosion resistance of ZrN and ZrSiN films deposited on AISI 430 steel by the magnetron sputtering technique. Corrosion resistance was evaluated using electrochemical impedance spectroscopy (EIS) technique, in 3.5% (wt./v) NaCl solution. The chemical and morphological film characterisation was carried out by Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction and scanning electron microscopy (SEM). The RBS analysis showed that 51.5Zr-48.5N and 43.5Zr-7.6Si-48.9N (at.-%) coatings were deposited by using magnetron sputtering technique on AISI 430 ferritic stainless steel. According to the results of EIS and SEM, the ZrSiN thin film was more homogeneous and effective in protecting AISI 430 steel against corrosion than the ZrN thin film, in the studied solution. The corrosion mechanism showed a difference: the ZrN-coated steel showed a localised corrosion through pores in the coating and the ZrSiN showed uniform corrosion at the coating-steel interface.

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Purpose – The purpose of this study is to evaluate the quality of organometallic coatings of automotive fuel tanks. Galvannealed steels and galvannealed steels coated with organometallic layers were analyzed using accelerated corrosion tests. Design/methodology/approach – The characterization of galvannealed and organometallic coatings was done by mass (layer removal and weighing) and layer thickness (glow discharge optical emission spectroscopy and scanning electron microscopy), chemical composition (energy dispersive spectroscopy) and surface morphology (scanning electron microscopy). The accelerated corrosion tests were performed in accordance with SAE J2334 and GMW 14872 standards. Findings – The samples tested using the GMW 14872 standard were more deteriorated as compared to the samples submitted to the SAE J2334 test because of the higher degree of aggressiveness of the GMW 14872 test. Despite the presence of white rust, the corrosion resistance of organometallic-coated steel samples was higher as compared to the resistance of galvannealed steel samples. Research limitations/implications – The organometallic coating is a commercial product, whose chemical composition is confidential. Practical implications – This study reinforces the quality of automotive tanks with organometallic coating and helps to increase their competitiveness in the market tanks as compared to polymeric tanks. Social implications – The study contributes to increase the competitiveness of steel tanks against polymeric tanks that meet the technical requirements but are not environmentally friendly because they are multi-layered and cannot be recycled. Originality/value – The novelty of this study is the comparison of the corrosion resistance of galvannealed steel tanks and galvannealed steel tanks with organometallic coatings. This corrosion evaluation joined with the physical and chemical characterization was not found in literature and is relevant to the materials selection of the automotive industry.