Band 43, Heft 3

Over the past two decades, research on alloys and composites based on Mg, Fe, and Zn has focused on biodegradable orthopaedic implants. Mg-based materials face issues like excessive corrosion rates and hydrogen gas evolution, while Fe and Zn-based materials show lower corrosion rates. However, these rates are slower than the optimal rate, which can be modified using powder metallurgy (PM) manufacturing. The PM process offers precise control over porosity distribution which in turn affects the mechanical and corrosion properties of the fabricated specimen. The highest rate of corrosion i.e. 0.944 mmpy was observed with the alloying of 2 wt% Pd in Fe and by using conventional sintering technique. Similarly, Zn-based samples fabricated by conventional sintering was found to exhibit higher corrosion rate as compared to microwave and spark plasma sintered specimen. PM-fabricated Fe and Zn-based bone scaffolds have been investigated for in-vitro corrosion and osseointegration. A higher porosity in the Fe and Zn scaffolds (>60 %) resulted in high corrosion rate which adversely impacted the cell proliferation. This timely review critically assessed PM-fabricated Fe and Zn-based materials that have the potential to transform regenerative medicine and patient care by redefining the field of biodegradable implants.

Microbially influenced corrosion and biofouling emerge as formidable challenges to the sustainable management and exploitation of marine resources. The primary instigator for these challenges lies in the insidious development of biofilm. Hence, the most direct and pivotal approach to counteracting microbial corrosion and biofouling resides in the advancement of anti-biofilm technologies. Conventional methodologies for combatting biofilm are efficient but have certain drawbacks, particularly environmental contamination and inefficacy. Research into innovative anti-biofilm technologies is imperative for more efficient use of marine resources and protection of the ecological equilibrium of the oceans. This paper offers a detailed examination of biofilm constituents, the complex processes involved in biofilm development, the various factors that affect biofilm formation, and the mechanisms underlying microbiologically influenced corrosion (MIC). Furthermore, the article summarizes emerging, eco-friendly anti-biofilm technologies, while providing the evolving landscape of anti-biofilm strategies and promising prospects.

Given the critical need for ocean exploration, improving the durability of materials in the deep-sea has become a paramount concern. The harshness of deep-sea, such as high pressure, variable seawater flow rates, and corrosive media, lead to premature aging and failure. This work examines the utilization of metals and polymer coatings in deep-sea applications, detailing the characteristics of the deep-sea and its influence on these materials. In particular, chloride ions in seawater pose significant hazards to metal corrosion, which is the main reason for metal failure. Then, the degradation process and the latest research advances of various materials in the deep-sea environment are summarized, and the failure mechanism of the metal/coating system in the deep-sea is analyzed. It was found that the failure of polymer coatings can be divided into three processes, and adding an appropriate amount of fillers to the coating (such as adding 0.2 % graphene to water-based polyurethane) can extend the service life of the coating. Finally, the development trend of the company in the future is predicted. It has guiding and reference significance for the study of the failure behavior of metals and polymers in the deep-sea environment.

Iron corrosion in acidic environments poses a significant challenge in various industries. This study explores the relationship between theoretical parameters and experimental data for organic corrosion inhibitors applied to iron surfaces in 1 M HCl solution at 25 °C. The review analyzes studies employing various techniques, primarily Electrochemical Impedance Spectroscopy (EIS), to assess inhibitor efficiency (IE%). Key theoretical parameters like E binding (interaction strength) and Δ N (electron transfer) are investigated for their ability to predict IE%. The findings reveal a strong correlation between experimental IE% and E binding , suggesting the potential of E binding as a reliable predictor of inhibitor performance before experimentation. While Δ N demonstrates promise in evaluating inhibitor effectiveness, further validation is necessary. Furthermore, the review emphasizes the possibility of using a single standardized method like EIS for inhibitor efficiency evaluation due to consistent results observed across studies with standardized conditions. Additionally, the influence of factors like molecular structure, surface interactions, and temperature on inhibitor effectiveness is highlighted. Higher inhibitor concentrations and lower temperatures generally resulted in improved corrosion inhibition. This review underscores the importance of a combined theoretical and experimental approach for the development of efficient and optimized corrosion inhibitors for iron in acidic environments.

In this study, a novel multifunctional copper nanoparticle CuNPs in the organic biomatrix was coated to the surface of Ti6Al4V to create multifunctional features. The synthesis of CuNPs was carried out by plant-mediated green synthesis method obtained from Moringa leaf extract, and the prepared CuNPs were coated on the substrate surfaces as single and double layers with drop casting methods. Characterizations of the synthesized CuNPs were performed by UV–Vis, FTIR, XRD, and SEM methods. Characterization of the modified Ti6Al4V alloy surfaces was performed using SEM-EDS and surface roughness analysis. The electrochemical corrosion, antibacterial behavior, and cytotoxic effects of coated and noncoated Ti6Al4V as a function of biocompatibility properties were also tested. The synthesized CuNPs have a homogeneously dispersed spherical shape. Biocorrosion tests have clearly demonstrated that the coating forms a protective film on the substrate surface, and the resistance increased by 49 %. Antibacterial results show that the single and double-coated Ti6Al4V alloy samples with CuNPs organic nanostructure had improved biocompatibility. However, it was determined that the cytotoxic effect increases proportionally with the coating. The obtained results show the importance of surface modification in the appropriate nanostructure to obtain multifunctional nanoplatforms that show promise in biomedical applications.

Waterline corrosion behavior of a weathering steel in static and dynamic simulated seawater was studied by means of wire beam electrode (WBE), scanning electron microscopy, and Fourier transform infrared spectroscopy in this paper. The results show that the distribution of cathode and anode on WBE surface was relatively stable under static condition with large cathode and anode structure. The region near the waterline was always a stable cathode, and the total anode current density decreased with time and basically stabilized after 6 days. Under dynamic condition, a large anode structure was formed on the WBE surface within 1 day, and the anodic current density rapidly decreased with time. The anode area gradually decreased and the WBE surface showed an alternating distribution of small anode and cathode after 3 days. The total anodic current density continued to decrease with time after 6 days. Under dynamic condition, the mass transfer of oxygen and other substances related to electrode reactions was accelerated, so that the anode surface was rapidly corroded in the early stage of immersion and covered by denser corrosion products, resulting in a positive shift in the potential and electrode reversal of some anode areas in the later stage.

As a part of pipeline systems, globe valves play an important role in cutting off and regulating fluid transmission in fields such as petrochemicals, coal chemicals, and metallurgy. During the transportation of corrosive fluid media, flow accelerated corrosion (FAC) caused by internal flow is the main form of valve failure, which seriously affects the safe and reliable operation of the entire transmission system. In this study, the effects of different valve openings and inlet velocities on characteristics of internal flows and corrosion were investigated by numerical simulations in globe valve. The distributions of velocity, pressure, and wall shear stress were obtained and discussed in detail. The corrosion rate of key components of globe valve was obtained and analyzed to reveal characteristics of FAC. Results show that the FAC is more serious with the increase of inlet velocity while it becomes the more serious at moderate valve opening degree. In addition, wall shear stress was verified to be able to describe FAC in globe valve. The obtained results were quite meaningful for guiding the structural design of globe valves in corrosion suppression, which extends the service life of globe valves and ensures the safety of conveying systems.