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Since testing organic coatings under natural conditions is a time‐consuming process, accelerated methods are needed to produce results in less time. A simulated environment cannot fully reproduce actual operating conditions, so it is important to investigate the correlation between accelerated and natural aging test results. In this article, the natural aging of painted steel, aluminum, and hot‐dip galvanized steel is studied for 1 year under continental climate conditions. The environmental parameters responsible for the change of the protective system in a continental urban environment were monitored: time of wetness, ultraviolet radiation, and temperature. The extent of deterioration is compared with similar samples weathered by accelerated testing using electrochemical impedance spectroscopy, differential scanning calorimetry, and gloss measurements. Neutral salt spray chamber, prohesion test, immersion in a quiescent salt solution, and ultraviolet B‐rays (UVB) exposure test are considered. The results of the accelerated cabinet tests are discussed, and the effect is evaluated for the various coated metals. This study highlights the major problems encountered in building a model to predict durability in such a critical area as the durability of organic coatings for metal structures. [ABSTRACT FROM AUTHOR]

Organic coatings delamination and corrosion pose an ongoing challenge in materials science. This review explores the knowledge of corrosion mechanisms in painted steel structures up to date, focusing on filiform corrosion (FFC) investigating its mechanisms, and discussing available prevention strategies alongside their suitability. First reported in the 1940s, FFC garnered significant attention in the subsequent decades, particularly in the study of coated aluminum, and very recently magnesium alloys. However, its consideration as a component of steel degradation remained comparatively limited during this period. Despite advancements, comprehensive analysis of FFC has been infrequent, prompting a call for an updated critical analysis. This survey emphasizes the necessity for organized FFC mitigation strategies, discussing alternatives and emerging trends. It underscores FFC's potential role as a precursor to general corrosion, emphasizing the economic implications of aesthetic damage. This review aims to fill gaps, assess current knowledge, and pave the way for future research in the realm of organic-coated steel corrosion. [Display omitted] • Filiform corrosion is a dramatic failure mechanism in organic-coated steel. • The coating delamination is verified to be driven by the anodic corrosion reactions. • The metal-paint interface is subjected to a harsh chemical environment discernible between anodic and cathodic sites. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of conversion coatings (CCs) in mitigating filiform corrosion (FFC) on acrylic-coated steel substrates, with a specific focus on iron phosphatizing and trivalent chromium conversion coatings. Aiming to evaluate the effectiveness of a simulated electrochemical approach introduced in a previous publication, several parameters are determined through an approach involving potentiodynamic polarization curves and zero resistance ammeter on bare CCs. These experiments are conducted in test solutions designed to replicate the electrolytic conditions the substrate encounters undergoing FFC. Similar measurements are collected in neutral testing solutions and the outcomes of the two approaches are discussed regarding the performances of the organic coated sample. The electrochemical evaluation of CCs highlights their potential to reduce the driving forces and nucleation tendency. However, for the steel coated with acrylic paint, while CCs reduce the initiation sites for delamination, they have limited impact on filament propagation. • Employing conversion coatings shows promise as an effective strategy to mitigate filiform corrosion on painted steel. • An electrochemical simulation approach can be applied to anticipate the performance of inorganic coatings. • Simulated quantitative data are deliberated in reference to the actual corrosion resistance. [ABSTRACT FROM AUTHOR]

Sebacate (SB) molecules were incorporated into Ca Al layered double hydroxides (CaAL-LDH) using a hydrothermal method. The resulting products underwent characterization through X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. To investigate the release kinetics and thermodynamics of the corrosion inhibitor, total organic carbon analysis (TOC) was employed. A comparison was made with CaAl-LDH prepared without corrosion inhibitors, in which nitrates were the primary anions within the layered clay structure. An assessment of anion exchange between nitrates and chlorides was conducted using total nitrogen analysis (TN). The SB anion comprised approximately 49.2% of the total dried powder synthesized, with a maximum release efficiency of around 86.7% fitting a Langmuir model. For the evaluation of the corrosion inhibition effect on steel surfaces, electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning vibrating electrode technique were employed. The corrosion inhibition impact was ascribed to the liberation of SB anions from the CaAl-LDH pigments, accompanied by alkalinization stemming from partial particle dissolution. Additionally, the incorporation of organic molecules notably enhanced the stability of pigments in aqueous solutions compared to similar ones hosting nitrates. These findings suggested that CaAl-LDH pigments have potential as nanocontainers for organic inhibitors, showing promising prospects in the field of corrosion research. [Display omitted] • Synthesis of CaAl-LDHs particles with sebacate intercalated. • Sebacate anionic exchange with chlorides is efficient at 86.7%. • Organic molecule intercalation gives improved stability in water. • Steel corrosion protection is provided by chloride trapping and inhibitor release. [ABSTRACT FROM AUTHOR]

A new approach to studying the mechanism of filiform corrosion in organic coated steel based on the scanning vibrating electrode technique (SVET) and micropotentiometry (potentiometric SECM) is presented. The electrochemical activity of the process under the coating is evaluated by mapping the ionic current densities emanating from some artificial defects made in specific locations of the filament identifiable thanks to the transparency of the coating. In addition, antimony tips are employed to investigate the pH changes associated to the different corrosion reactions at the metal-paint interface. Local pH levels associated to anodic and cathodic regions are determined along the filament. [Display omitted] • Anodic and cathodic areas of filiform corrosion on organic-coated steel were identified by SVET. • The activity in the head confined into the "V-shape" morphology resulted anodic and the entire length of the tail cathodic. • Scanning micropotentiometry with an antimony microelectrode allowed local pH distributions in the filament to be measured. [ABSTRACT FROM AUTHOR]

The filiform corrosion mechanism on acrylic-coated steel is investigated through potentiodynamic curves collecting anodic and cathodic branches in two different electrolytes simulating the liquid environments at the metal-paint interface. Zero resistance amperometry was chosen as an additional tool to achieve numerical results. The potential difference and the current density between the anodic and cathodic portions of the filament tip were estimated using a simplified setup. The role of oxygen availability on the corrosion mechanisms was also investigated by modifying the amount of dissolved oxygen in the simulating electrolytes and the humidostatic chamber employed for FFC propagation. [Display omitted] • Acrylic-coated carbon steel is susceptible to filiform corrosion. • The leading head is characterized by a typical "V-shape". • The morphology and the corrosion rate are determined by the oxygen available. • Electrochemical analyses are able to assess the driving force of the mechanism. • Anode and Cathode reactive sites have comparable areas. [ABSTRACT FROM AUTHOR]

Highlights: [•] We compared the combustion of vineyard pruning residues and wood chips. [•] Flue gases and heavy metal emissions were considered. [•] Emissions from combustion of vineyard residues resulted within legal limits. [•] Electrostatic filters reduced the human toxicity potential factor of emissions. [•] Agro and forest biomass showed no difference in terms of heavy metals emissions. [ABSTRACT FROM AUTHOR]