Volume 43, Issue 4

Green corrosion inhibitors are produced from economical and renewable sources and concurrently offer high inhibition efficiency and very low negative effects on environment. Various naturally occurring biomacromolecules are employed as corrosion inhibitors for steels. In contrast to small molecule corrosion inhibitors, polymers possess superior film-forming abilities and multifunctional chemistries that have the potential to enhance protective barrier characteristics greatly. Moreover, the biomacromolecules have many sites of attachment which further enhance their inhibition ability. This featured article is dedicated to summarizing the inhibition performance of biomacromolecules to mitigate mild steel corrosion in acidic media. It began by describing the green corrosion inhibitors and the advantages of using biomacromolecules as inhibitors. All naturally occurring macromolecules such as such as carbohydrates, proteins, and nucleic acids, have been focused as inhibitors for mild steel in acidic media with their inhibition action. The factors affecting inhibition efficiency like temperature, inhibitor concentration, exposure time, etc. are also discussed. In the last, the synergistic effect of other ions with macromolecules in corrosion inhibition was also taken into consideration. This review offers insightful observations into the development of biomacromolecules as green corrosion inhibitors.

This review examines copper corrosion mechanisms and their key influencing factors, including microstructure effects, surface treatments, manufacturing conditions, temperature, water chemistry parameters, fluid velocity, and microbial effects in water-based systems, with a particular focus on heat exchangers. This addresses a critical gap in the existing literature, which often examines copper corrosion in a broader context. By critically analyzing the literature, the review provides an in-depth understanding of the factors that govern copper corrosion in heat exchanger applications. Copper corrosion in heat exchangers can have significant technical and social detrimental consequences, leading to substantial economic losses. By focusing on heat exchangers, the review offers valuable insights and best practices for engineers, researchers, and practitioners working with copper in this domain. Furthermore, the review evaluates the latest mitigation strategies, including advancements in material selection, surface treatments, water treatment techniques, and robust monitoring/maintenance methods. Finally, the review explores promising new concepts for corrosion prevention for long-term performance, paving the way for future research in developing innovative technologies and refining highly effective strategies under diverse operating conditions relevant to combat deleterious copper corrosion effects in heat exchanger applications.

Aiming at the shortcoming that when applied to nonferrous copper 62 surfaces, epoxy coatings are prone to aging in marine environments. In order to extend the service life of copper 62 coatings in marine environments, methods of screening the corrosion inhibitor commonly used in copper 62 alloys and adding it to epoxy organic coatings have been investigated. Tafel polarization test and electrochemical impedance spectroscopy (EIS) were used to study the corrosion inhibition effect of different corrosion inhibitors on copper 62 alloy in simulated marine environment, and the influence of MBI on the damage process and water transport of epoxy coatings was studied by EIS. The results show that 2 mercaptobenzothiazole (MBT) has good corrosion inhibition on copper 62 alloy in marine environment. When the total mass fraction is 0.5 wt%, the corrosion suppression can reach 96.4 %. When MBT is added to the epoxy organic coating at 0.5 wt%, the diffusion coefficient of the coating is as low as 8.35 × 10 −11  cm 2  s −1 , and the failure time of the coating is extended to 1824 h. It has been shown that the addition of MBT can effectively improve the service life of copper 62 alloy/epoxy coatings in marine environments.

Engineering materials are known to show degradation in terms of tribo-corrosion characteristics in marine environment. The concurrent increase in erosion and corrosion resistance can make them more appealing for structural applications. The thermal spray coatings are typically used to mitigate the degradation of structural components. Although, the microstructure of as-sprayed coating indicates inconsistency in the form of distinct splats and elemental segregation. Furnace annealing, microwave processing and stationary friction processing (SFP) are performed to improve the non-homogeneous microstructure of the thermal spray coating. SFP has several attractive properties to refine the grain structure and reducing the defects density on the surface. Therefore, SFP has been explored as a surface modification technique for thermal spray coating with an aim to enhance the performance of the processed coating. Slurry erosion and erosion corrosion tests are conducted on as-sprayed and processed coatings at normal and oblique impingement angle. Erosion rate of SFPed specimen is comparatively lower than that of the as-sprayed, furnace annealed and microwave processed specimens in both slurry erosion and erosion corrosion. Furthermore, the SFPed coating indicated least corrosion rate as compare to furnace annealed, microwave coating and as-sprayed coating.

The corrosion behavior of 12Cr1MoVG tube in a waste incineration boiler superheater was investigated using on-site and laboratory testing. Low-melting-point ZnCl 2 and PbCl 2 induced the formation of eutectic mixtures. These eutectic mixtures captured ash particles, resulting in severe slagging on the 12Cr1MoVG tube. The structure of the oxide layer on the 12Cr1MoVG tube was severely disrupted by the high S and Cl contents in waste fuel. Under the influence of brittle Fe 2 O 3 and FeS spalling, FeCl 2 dissolution, FeCl 3 and FeSO 4 volatilization, and severe internal oxidation, corrosion perforation appeared in the 12Cr1MoVG tube.