Corrosion and Materials Degradation

During industrial construction, steel measuring tapes are frequently exposed to alkaline cement environments, leading to rapid degradation of protective coatings and corrosion of the steel substrate. In this study, acrylic–amino resin composite coatings incorporating three different inhibitor systems (RZ/ZMP, RZ/ZPO, and RZ/ZPA) were prepared, and their corrosion resistance in alkaline media was systematically evaluated. The microstructure and composition of the coatings were characterized by SEM, EDS, and XRD, while surface wettability was assessed by water contact angle measurements. Corrosion protection performance was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and long-term alkaline immersion tests. The results show that the incorporation of inhibitors significantly enhances the corrosion resistance of the coatings. Compared with the inhibitor-free acrylic–amino resin coating, the corrosion current density of the RZ/ZPA coating decreases by approximately 1.9 times, while that of the RZ/ZPO coating decreases by about 1.7 times. EIS analysis further reveals that the RZ/ZPO/acrylic–amino resin coating exhibits the highest coating resistance (1.41 × 10⁷ Ω·cm²), which is approximately 4.2 times higher than that of the inhibitor-free coating and 188 times higher than that of the steel substrate, indicating the strongest ion-blocking capability. Based on combined electrochemical parameters and long-term alkaline immersion behavior, the corrosion resistance of the coatings increases in the following order: acrylic–amino resin coating < RZ/ZPA < RZ/ZMP < RZ/ZPO. Overall, the synergistic effect of multiple inhibitors significantly improves both the electrochemical corrosion resistance and long-term alkaline durability of acrylic–amino resin coatings.

Galvanic corrosion is an electrochemical phenomenon that arises due to the coupling of two different metals in an electrolytic environment, resulting in the deterioration of the less noble metal at an accelerated rate. This phenomenon poses a significant challenge in the economy of mixed-metal assemblies in many industrial applications due to the high maintenance and replacement expenditures that such systems incur. In this study, a stainless steel tube was galvanically coupled with a carbon steel fitting, and both were immersed in a chloride solution to study the galvanic interactions. The electrochemical processes associated with galvanic corrosion were simulated using a finite element multiphysics modeling approach (COMSOL Multiphysics). The simulations reproduced the metal–electrolyte interface potential and current density as well as the preferential anodic dissolution of carbon steel over stainless steel, which was observed during the coupled polarization. The numerical results matched the results predicted using assumptions for the steels’ electrochemical behavior. The results of the study confirmed that finite element simulation is an effective means of modeling galvanic corrosion and optimizing the design and life of metal component assemblies that are subjected to highly aggressive environments such as high-chloride environments. The numerical results matched the trends observed from experimentation and those previously reported in the literature and serve to provide qualitative and semi-quantitative insight regarding galvanic corrosion mechanisms instead of complete corrosion predictions regarding long-term corrosion behavior.

The present work aims to evaluate the electrochemical behaviour of 316L stainless steel flat sheets both uncoated and coated with an organic–inorganic silane hybrid formulation based on TEOS (tetraethyl orthosilicate) and TMES (Trimethylethoxysilane) as silane precursors. The influence of the modification of the silane-based layer by the incorporation of 3-aminopropyl trimethoxysilane (APS) doped TiO₂ (N-TiO₂) on the pitting properties of the coatings has been studied. The obtained protective films have been characterized from compositional (EDX), morphological (FE-SEM), and electrochemical (corrosion) points of view. Concerning their morphology, the coatings look continuous and smooth. Regarding their electrochemical properties, the results show that the application of the developed N-TiO₂-containing silane coatings extends the passive potential range of 316L stainless steel in simulated body fluid; thus, it improves the pitting resistance of the substrate.