Corrosion Resistance Of Materials Research Articles

DFT Approach in Corrosion Research

Corrosion, degradation of materials due to environmental chemical reactions, poses significant challenges across various industries. This study emphasized the importance of Density Functional Theory (DFT) in understanding corrosion mechanisms and developing effective corrosion inhibitors. The role molecules were 1,2-dihydroxybenzene, m-guaiacol, and catechin, which were investigated via DFT analysis in order to determine their corrosion inhibition performance. Key parameters, including the energy gap (∆E), absolute electronegativity (χ), hardness (ɳ), softness (δ), and dipole moment, were analyzed to investigate their efficiency. Catechin, with its lowest ∆E, demonstrated enhanced electron-donating capabilities, indicating high inhibition performance. Additionally, electrochemical impedance spectroscopy confirmed corrosion protection efficiency for these compounds. Despite the limitations of DFT, such as computational demands and the need for accurate exchange-correlation functionals, advancements in computational methodologies and integration with experimental data can enhance its predictive power. This study highlights the importance of DFT in guiding the design of corrosion-resistant materials and emphasizes the need for interdisciplinary collaboration to refine theoretical models and validate predictions.

A Review of Up-To-Date Research Knowledge on the Corrosion Inhibiting Capability of Garlic (Allicin Sativum) for Steel Materials

Corrosion is a monumental economic and technological problem worldwide. Despite the poor corrosion resistance of steel material, contributing to about 90% of all corrosion problems worldwide, it remains the most versatile and critical structural material in the construction of automobiles, ships, aircraft, rail transport systems, engine systems, pipeline systems, bridges, buildings, petroleum refineries, etc. Corrosion inhibitors are effective alternatives for protecting steel against corrosion in aqueous environments. Synthetic corrosion inhibitors pose serious problems to global environmental issues and health risks in usage to reduce corrosion of large amounts of steel goods, so natural plant extracts have been under study for replacing synthetic inhibitors in various environments due to their excellent environmental properties, handling safety, and good corrosion inhibition capabilities. This paper aims to present up-to-date research knowledge on the corrosion inhibition capability of garlic for steel materials, covering its requirements as a potential corrosion inhibitor and various research studies on its steel corrosion inhibition capability in various aqueous environments as integrated knowledge for application. The review shows that garlic is a very effective corrosion inhibitor of steel corrosion. It is also a safe-for-handling, biodegradable, and ecofriendly plant that is sustainably available around the world. Its extracts can be dependably prepared in sufficient quantity around the world for corrosion inhibition of steel materials and some other purposes. However, little is seen to have been done with the existing research findings for practical protection of steel materials in various aqueous environments. The review information is therefore posited for standardization and commercialization consideration of garlic extracts as corrosion inhibitors for practical corrosion inhibition of steel materials or further research requirements.

Hollow conductive polypyrrole microtubes as microwave absorbents with good seawater corrosion resistance

Conductive polymers materials with hollow micro/nanostructure due to their special electrical properties and corrosion resistance have potential applications in microwave absorption, especially in marine environment. Herein, one-dimensional hollow conductive polypyrrole microtubes (H-PPyM) were prepared by in-situ polymerization of pyrrole monomer with methyl orange (MO) as soft template and FeCl3 as oxidant based on structural regulation strategy. The morphology and conductivity of H-PPyM can be easily controlled by adjusting the content proportion of MO. The results indicated that the surface morphology of polypyrrole changed from random granular to microtubular and the conductivity also gradually rose with the content increase of MO. When the content proportion of MO was 0.25 g, the obtained H-PPyM-0.25 composites possed notable microwave absorption capacity, simultaneously achieving ultrabroad effective absorption bandwidth (EAB, 6.7 GHz) and strong reflection loss value (RL, -33.6 dB) at a thickness of 2.6 mm with the filling content of only 10 wt.%, respectively. Furthermore, the corresponding H-PPyM-0.25 products soaked in corrosive medium (3.5 wt% NaCl solution) for one month still displayed stable tubular hollow structure and excellent microwave absorption performance with RLmin of -43.8 dB and EAB of 6.2 GHz. The research results can not only help to understand the relationship among the morphology and microwave absorption of PPy, but also open a new avenue for preparing excellent seawater corrosion resistant microwave absorption materials.

Failure and Degradation Mechanisms of Steel Pipelines: Analysis and Development of Effective Preventive Strategies.

The increasing challenges related to the reliability and durability of steel pipeline infrastructure necessitate a detailed understanding of degradation and failure mechanisms. This study focuses on selective corrosion and erosion as critical factors, analyzing their impact on pipeline integrity using advanced methods, including macroscopic analysis, corrosion testing, microscopic examination, tensile strength testing, and finite element method (FEM) modeling. Selective corrosion in the heat-affected zones (HAZs) of longitudinal welds was identified as the dominant degradation mechanism, with pit depths reaching up to 6 mm, leading to tensile strength reductions of 30%. FEM analysis showed that material loss exceeding 8 mm in weld areas under standard operating pressure (16 bar) induces critical stress levels, risking pipeline failure. Erosion was found to exacerbate selective corrosion, accelerating degradation in high-stress zones. Practical recommendations include the use of corrosion-resistant materials, such as duplex steels, and implementing integrated monitoring strategies combining non-destructive testing with FEM-based predictive modeling. These insights contribute to developing robust preventive measures to ensure the safety and longevity of pipeline infrastructure.

Impact of the Plastic Deformation Microstructure on the Corrosive Resistance of Metallic Materials – The State of the Art and the Effect of Microstructure Refinement on the Example of the 2000 Series Aluminum Alloy

The article discusses the role of the microstructure formed through plastic deformation in the corrosion resistance of metallic materials. Additionally, a review of the existing knowledge in this area is conducted. In particular, the role of the refinement of intermetallic phases is emphasized. For that purpose, investigations of as-cast aluminum alloy, as well as after plastic deformation, from the 2000 series have been performed. Metallographic tests of the examined materials have been carried out, and electrochemical tests as well as SEM examinations of the surface after the corrosion tests have been conducted. It has been documented that the presence of large precipitates existing at distances typical of as-cast alloys favours intensive corrosion. In turn, a significant amount of fine-dispersive precipitates at the initial stage of corrosion can work as a barrier counteracting the corrosion processes.

Research on Modified Thermal Barrier Coatings Against CMAS Corrosion Driven by Mechanism–Data Hybrid Model

With the development of high-efficiency gas turbine engines and increasing inlet temperatures, the performance of thermal barrier coatings (TBCs) for hot-section components has been more severely challenged. The doping of multi-element rare earth elements significantly improves the thermodynamic properties and chemical compatibility of thermal barrier coatings so that the application performance of coatings in high-temperature environments is enhanced considerably. In this work, the doped coatings prepared by REYSZ (RE = La, Sm, Nd) were investigated and characterized in terms of crystal structure, elastic properties, and thermal–mechanical properties based on the first-principles approach, combined with various empirical and semi-empirical formulations, and a predictive model for resistance to CMAS corrosion based on machine learning approaches. The results showed that the tetragonal phase REYSZ material was mechanically stable, had a large strain damage tolerance, and was not easy to fracture under applied loads and thermal shocks. In terms of CMAS corrosion resistance, the NdYSZ interfacial model had a lower surface energy (3.130 J/m2) and Griffith fracture energy (6.934 J/m2) compared with the conventional YSZ model, and Nd2O3 had the potential to improve the CMAS corrosion resistance of zirconia-based material for thermal barrier coatings. By evaluating the machine learning prediction models, the regression coefficients of the two algorithms were 0.9627 and 0.9740, and both these two prediction models showed high prediction accuracy and strong robustness. Ultimately, this work presented a novel mechanism–data hybrid method, which would facilitate the efficient development of TBC new materials for anti-CMAS corrosion.

Kinetic and Thermodynamic Aspects of the Degradation of Ferritic Steels Immersed in Solar Salt.

The study and improvement of the corrosion resistance of materials used in concentrated solar power plants is a permanent field of research. This involves determining their chemical stability when in contact with heat transfer fluids, such as molten nitrate salts. Various studies indicate an improvement in the corrosion resistance of iron-based alloys with the incorporation of elements that show high reactivity and solubility in molten nitrate salts, such as Cr and Mo. This study analyzes the kinetic and thermodynamic aspects of the beginning of the corrosion process of ferritic steels immersed in Solar Salt at 400, 500, and 600 °C. The analysis of the kinetic data using the Arrhenius equation and the Transition State Theory shows that an increase in the Cr/Mo ratio reduces the activation energy, the standard formation enthalpy, and the standard formation entropy. This indicates that its incorporation favors the degradation of steel; however, the results show a reduction in the corrosion rate. This effect is possible due to a synergistic effect by the formation of insoluble Fe-oxide layers that favor the formation of a Cr oxide layer at the Fe-oxide-metal interface, which limits the subsequent oxidation of Fe.

AN ASSESSMENT OF PHASE CHANGE MATERIAL, PREPARATION TECHNIQUES AND CONTAINMENT MATERIAL WITH DIFFERENT MOLTEN SALTS FOR THERMAL ENERGY STORAGE SYSTEM

Molten salts are extensively used as high-temperature heat transfer media and thermal energy storage (TES) materials in concentrating solar power (CSP) plants. Molten salt corrosion is a critical factor influencing the safe operation of the system. This work comparatively summarizes various factors influencing molten salt corrosion, including temperature, impurities, alloy composition and gas atmosphere. Additionally, the corrosion mechanisms of nitrate, carbonate, chloride, and fluoride-based mixture salts are meticulously reviewed. The demand for high-temperature storage is indeed increasing, driven by the need for more efficient and sustainable energy solutions. High-temperature storage systems, particularly those utilizing phase change materials (PCMs) and molten salts, play a key role in enhancing energy efficiency and reducing carbon footprint. By improving the efficiency of energy storage and reducing the need for fossil fuels, high-temperature storage systems help decrease greenhouse gas emissions, contributing to the fight against global warming. The paper focused on enhancing the corrosion resistance of container materials in terms of improving PCM thermal conductivity and stability.

(Corrosion Division Morris Cohen Graduate Student Award) Respirometric Monitoring of Corrosion

Accurate measurement of the corrosion rate of metals and alloys under realistic exposure conditions is crucial for the elucidation of corrosion mechanisms, the development of new corrosion protection measures, and for reliable corrosion prediction. A respirometric approach to monitor corrosion rates based on quantifying the rates of the main cathodic reactions during corrosion is presented. With the proposed gravimetric, manometric, or flow cell experimental setups it is possible to follow the rates of the H2 evolution reaction (HER), the O2 reduction reaction (ORR), or both cathodic reactions simultaneously.The respirometric method can universally provide real-time corrosion rate monitoring for atmospheric corrosion conditions under thin electrolyte films, where suitable corrosion monitoring capabilities have been lacking so far. Furthermore, respirometric methods applicable to corrosion under immersion conditions are presented and coupled with electrochemical measurements. It was demonstrated on various relevant engineering metals and alloys that reliable and sensitive real-time monitoring is possible without influencing the corrosion process by the measurement itself. The accuracy and validity of the developed methodology was confirmed by independent parallel measurement methods such as mass loss, solution analysis by ion chromatography, profilometry, and electrochemical measurements. Parallel imaging of the corroding surface was carried out to visually link changes of the respirometric rates and of the exposure conditions to observations of the surface morphology, gas evolution and corrosion propagation.Besides measuring corrosion rates, the respirometric method can be used to elucidate corrosion mechanisms. The effect of changes in different exposure conditions on the corrosion rate and on the rate of the cathodic reactions could be followed in situ. This includes changes in the temperature, the composition of electrolyte, or wet–dry cycling. The role of the ORR for Mg alloy corrosion was investigated and it was found that besides HER, the ORR contributes substantially to the cathodic reactions both for atmospheric corrosion and immersion. A change in the mechanism from ORR to HER was observed with the onset of localized corrosion of Al alloys under atmospheric conditions. In the context of biodegradable metallic implants, the time-dependent corrosion behavior of Zn and Mg alloys was investigated and compared in simulated body fluids of increasing complexity. The contribution of the two-electron ORR pathway was confirmed for Zn under immersion conditions and quantified for the different simulated body fluids.By coupling the respirometric method with electrochemical measurements, it was shown that the contribution of the involved reactions and pathways to the net electric current can be extracted at different applied currents or potentials. As a result, it was possible to deconvolute dynamic polarization curves into the contributing partial reactions. Unexpected cathodic reactions (negative difference effect) during localized corrosion at anodic polarization as well as unexpected anodic dissolution (cathodic corrosion) under cathodic polarization could be revealed and quantified with the respirometric method. Moreover, the fraction of anodic current related to the O2 evolution reaction could be differentiated from the fraction of current that caused transpassive corrosion.A more sensitive respirometric method was developed that is suitable to measure corrosion rates of more corrosion resistant materials or materials in weakly corrosive environments. Corrosion scenarios that were investigated with this high resolution respirometric method include breakdown of passivity of Al and stainless steel, H2 evolution of Zn anodes in Zn ion batteries and corrosion of metals in ionic liquids. While this approach is certainly promising for laboratory applications, also the applicability to respirometric field measurements will be demonstrated. A respirometric probe was developed that can be attached to corroding structures in the field.Overall, the respirometric method provides a monitoring tool to establish the relationship between relevant exposure parameters and accurate corrosion rates. The advantages and possibilities of the developed respirometric methods open up new doors to in situ investigation of corrosion and other electrode processes Figure 1

Influence of Phosphorus on Initial and Long-Term Atmospheric Corrosion Behavior of Steel Materials

Phosphorus is contained as an impurity in the manufacturing process of steel materials, and it is known to be difficult to remove it completely, and it is also thought to influence the corrosion resistance of steel materials. However, the effect of phosphorus on corrosion resistance has not been clarified, because the steel materials used in previous research reports also contain copper and chromium. The aim of the present study was to systematically examine the influence of phosphorus on the corrosion behavior from early to long-term.Fe-P binary alloys containing 0.5, 1.0 and 1.5 mass% P were used as the samples. The sample grinded with SiC and diamond paste were prepared for electrochemical measurements. Anodic polarization measurements were performed in 25℃ of boric acid-borate buffer solution (pH 8.0) containing 10 mM NaCl in a non-deaerated environment. Platinum was used as the counter electrode and an Ag/AgCl electrode (3.33 M KCl) as the reference electrode. Before the polarization measurements, the immersion potential was measured for 10 min. and then cathodically treated at -1.0 V for 10 min. The sweep rate was 20 mV/min. In addition, the surface was observed by SEM and EDS after polarization at 0.2 V for 80 s to investigate the starting point of localized corrosion of the Fe-1.5 mass% P.EDS analysis was performed on all sample surfaces before electrochemical measurement. The distribution of phosphorus concentration was not observed on Fe-0.5 mass% P, whereas horizontal banded macro-segregation of phosphorus was observed on Fe-1.0 mass% P and Fe-1.5 mass% P. Furthermore, as a result of EDS analysis with a higher magnification, intergranular segregation of phosphorus was observed only on Fe-1.5 mass% P.In the anodic polarization curves of all samples, a peak was observed in the potential range of about -0.66 to -0.39 V, which could be attributed to the active dissolution of the sample. No increase of the current density was observed in the lower potential range than about 0.05 V, suggesting that the sample surface was passivated in this potential range. On the other hand, the current value increased significantly in the potential range higher than 0.05 V, due to the occurrence of localized corrosion. The current density of Fe-1.5 mass% P increased at lower potentials than for the other samples.Polarization measurement of Fe-1.5 mass% P was conducted at a constant potential to investigate the starting point of localized corrosion. A rapid increase in anode current was observed after approximately 10 seconds. SEM observations and EDS analysis were conducted on the sample surface after the test. A number of localized corrosion of about 5 µm in size was observed on the sample surface after the test. EDS analysis showed that higher concentrations of Si and Mn were detected in the corroded areas. In addition, localized corrosion with an elongated shape was also observed on the Fe-1.5 mass% P surface. Since no alloying elements (Mn and Si) derived from inclusions were detected in the corroded areas, this localized corrosion is considered to be due to intergranular segregation of P.The exposure test of all samples was conducted at Miyakojima Island, Japan for 5 years. The corrosion loss of Fe-1.5 mass% P was the smallest compared to the other samples, suggesting that the higher the P content, the lower the corrosion loss. EPMA analysis was conducted for the cross-section of the rust layer of samples after long-term exposure. P was partly concentrated in the rust layer of Fe-0.5 mass% P, but Cl penetrated into the rust layer and reached the steel substrate. On the other hand, P was fully enriched in the rust layer of Fe-1.5 mass% P and Cl was present only on the surface of the rust layer. The protective function of the rust layer due to phosphorus enrichment may have contributed to the long-term improvement of corrosion resistance.

(Invited) Rust Design for Corrosion Protection of Steel Exposed to Atmospheric and Marine Environments

Steel materials have been used in many fields as basic materials for infrastructures due to their superior strength and toughness. However, steel is significantly more susceptible to corrosion in atmospheric corrosive environments than other metals such as copper- or zinc-based materials. The large corrosion rate of steel is greatly affected by iron rust, which is a corrosion product formed on the steel surface as a result of corrosion. In general, the rust layer has poor corrosion protection properties and rather accelerates corrosion because it accelerates electrochemical reactions. To provide corrosion protection ability to the rust layer, which adversely can suppress the corrosion of steel materials, would enhance the corrosion resistance of steel in atmospheric and marine environments. The author and co-researchers have investigated the structure and electrochemical properties of the rust layer on steel and have attempted to design rust to actively increase the protectiveness of the rust layer against corrosion.The major rust components commonly found in the atmospheric environment are iron oxyhydroxide (α-FeOOH, β-FeOOH and γ-FeOOH) and iron oxide Fe3O4. β-FeOOH is structurally stabilized by the presence of Cl, so it is often found in environments with large amounts of salt such as marine environments. Among the isomers of iron oxyhydroxide, the thermodynamic stability differs, with α-FeOOH being the most stable. The author and co-researchers have elucidated that the rust layer mainly composed of the α-FeOOH structure has high corrosion protectiveness. The main reason for this is thought to be the suppression of the rust reduction reaction and therefore the reduction of the cathodic reaction rate. Since γ-FeOOH in the rust layer changes to α-FeOOH with long period of time, the mass fraction of α-FeOOH-structured rust, α/γ and α/γ*, which are reported as the protective ability index (PAI) of the rust layer, monotonically increases over thousands of years (Fig. 1). The corrosion rate of steel with rust layer decreases as the mass fraction of α-FeOOH structural rust, PAI, increases. [Yamashita et al., Corros. Sci. 36, 283(1994); Yamashita et al., The Sumitomo Search, 57, 12(1995); Dillmann et al., Corros. Sci., 46, 1401(2004); Kamimura et al., Corros. Sci., 48, 2799(2006)]In order to enhance the protectiveness of the rust layer, doping of nonferrous metallic elements into the rust layer would be effective. For example, it has been shown that Cr doping in α-FeOOH leads to crystal grain refinement and ion selective permeability. XAFS analysis using synchrotron radiation [Yamashita et al., Materials Science Research International, Special Technical Publication-1, 398-401(2001); Yamashita et al., Corros. Sci., 45, 381(2003)] revealed that Cr is adsorbed on the surface of α-FeOOH crystal as CrOX 3-2X [Konishi et al., Materials Transactions, 46, 337(2005)]. On the other hand, doping of Al, Ni, and Zn in the rust layer increases α-FeOOH and decreases the oxygen reduction rate, suppressing the cathodic reaction. In particular, Zn also suppresses the reduction of rust since Zn behaves as a substitutional element to Fe, which has been elucidated from anomalous dispersion behavior measurements using synchrotron radiation X-rays [Deguchi et al., SPring-8/SACLA Research Reports, Section B, 366(2023)]. In addition, doped Ni changes tetragonal crystal structure of β-FeOOH to monoclinic structure resulting formation of Fe7.6Ni0.4O6.35(OH)9.65Cl1.25 [Post and Buchwald, Am. Min. 76, 272(1991)] that increases protectiveness of the rust layer even in chloride airborne environments [Hayashida et al., Materials Transactions, 62, 781(2021)].These facts suggest that anticorrosive rust design is possible by utilizing nonferrous metallic elements. In fact, it has been shown that when various metallic compounds that are expected to have rust design effects are added to a paint, the rust layer of a rusted steel coated with the paint is modified and corrosion resistance of the rusted steel is significantly improved (Fig. 2) [Yamashita et al., Corrosion Engineering, 66, 64(2017)]. It is hoped that further development of this rust design will improve the corrosion resistance of steel materials and extend the service life of steel infrastructure. Figure 1

Corrosion, Impact Toughness and Tensile Properties of Duplex Stainless Steels Manufactured by Directed Energy Deposition

Duplex stainless steels provide a desirable combination of corrosion resistance, strength and toughness. Additive manufacturing of duplex stainless steels can be challenging due to high cooling rates and repeated reheating, which can produce detrimental microstructural constituents. In this study, a coaxial directed energy deposition system with laser and wire was used to deposit 2205, 2209 and 2509 duplex stainless steels. Corrosion resistance, strength and impact toughness in both as-built and solution annealed condition was tested and the microstructure was characterized. Solution annealing improved impact toughness considerably, produced a slight increase in corrosion resistance and a slight decrease in tensile strength. The 2205 material surpassed all common requirements and exhibited better corrosion resistance than 2209 due to less segregation between austenite and ferrite. Segregation of alloying elements was lower in intragranular austenite than grain boundary allotriomorph and Widmanstätten austenite. The 2209 and 2509 materials provided relatively low strength, especially in the solution annealed condition. For the 2509 material, sigma phase caused low as-built corrosion resistance and impact toughness. Overmatching welding consumables were found to be less suitable as feedstock for additive manufacturing due to high austenite content in the deposited material and lower corrosion resistance than conventional duplex compositions.

Insights into local wall erosion characteristics and prevention measures for cyclone separators

Cyclone separators are separation devices that use the principle of inertia to remove particulate matter from flue gases. The present study mainly focuses on wall erosion in cyclone separators and associated research. The main locations of erosion in gas–solid cyclone separators, including the entrance impact section, cyclone roof corner, vortex finder outer surface, spiral-type erosion strip, and lower cone section, are examined in detail. The main factors influencing wall erosion are discussed, including inlet flow velocity, solid particle properties and loading, geometrical structure, and manufacturing quality. Finally, several practically preventive measures against wall erosion are presented, including adjustment of operating conditions, the use of erosion-resistant materials, optimization of geometrical structures, and the addition of auxiliary devices, all of which are essential for ensuring operational efficiency, equipment reliability, safety, and environmental protection in various industrial applications. This paper aims to provide a basis for further research into erosion in cyclone separators as well as guidance for engineers involved in their industrial applications.

Achieving superior wear and corrosion resistance in FeCoNiCrNC films via nitrogen and carbon dual anions incorporation

Developing film materials thatcombine toughness, wear resistance, and corrosion resistance is a major challenge in the field of surface protection. Doping non-metallic elements such as nitrogen and carbon into high-entropy alloy films is expected to improve their overall performance. In this study, we successfully prepared nitrogen and carbon co-doped FeCoNiCrNCx high-entropy composite films using reactive magnetron sputtering. We systematically investigated the effects of different carbon concentrations on the structure, mechanical properties, friction, and corrosion resistance of the films. The results show that compared to carbon-free films, FeCoNiCrNCx high-entropy composite films with low carbon content (1.2 at.%) have remarkable characteristics, including high hardness (15.1 GPa), good toughness, excellent wear resistance (2.19 × 10-7 mm3N-1m−1), and corrosion resistance. As the carbon content increasing further, the precipitation of the amorphous carbon phase decreases hardness and toughness, reducing wear and corrosion resistance. The exceptional wear and corrosion resistance of low-carbon films make them highly promising for marine equipment protection and similar applications.

Development of a material selection decision support system for an automotive application

This study presents the development of a material selection decision support system for an automotive rooftop tent. The system uses five parameters of material cost, formability, corrosion resistance, tensile strength and hardness to optimize material choice from a list of aluminium alloy options. This was done before production via the deep drawing process can commence. The parameters were quantified using the average market prices for each alloy, product requirements obtained from the case study and the performance data that was obtained from the uniaxial tensile and hardness tests. These inputs were combined with the developed material selection framework and then programmed into a web-based decision support system for automated, data-driven material selection. The output presents the recommendation for the optimum material that balances cost-effectiveness and performance. The decision support system was successfully used to select the optimum alloy for the rooftop tent. Results show that AA1050 is the optimum material, providing weight reduction at the minimum achievable cost without compromising the product requirements for the rooftop tent. The decision support system is also scalable, and this allows it to be used with larger datasets for different products and processes in the future.

Bioresorbable composites based on magnesium and hydroxyapatite for use in bone tissue engineering: Focus on controlling and minimizing corrosion activity

A biodegradable matrix with a significant content of bioactive components can be applied for bone tissue replacement, including load-bearing applications in orthopedic surgery. The study outlines the optimized procedure for the production of bioresorbable magnesium-hydroxyapatite (Mg-HA) composites and their corrosion resistance properties. Composites were meticulously crafted by combining pure magnesium with microwave-synthesized hydroxyapatite nanopowder. Sintering occurred via spark plasma sintering technology (SPS). To align the degradation time of the resulting composites with bone remodeling, the corrosion resistance of SPS materials was enhanced through the application of plasma electrolytic oxidation (PEO) and polycaprolactone (PCL) spin-coating methods. The protective properties, morphology dynamics, and composition due to surface treatment and corrosion propagation were investigated using Electrochemical Impedance Spectroscopy (EIS), Potentiodynamic Polarization (PDP), hydrogen evolution tests, Scanning Electron Microscopy (SEM), Energy-dispersive X-ray (EDX) as well as X-ray diffraction (XRD) analysis. Analytics of the physicochemical properties data of the formed coatings indicate a significant improvement in protective characteristics and deceleration of the corrosive degradation of the samples. The application of polycaprolactone to the PEO coating leads to a decrease in the corrosion current compared to uncoated magnesium composites by more than three orders of magnitude: from 1 10−5 to 2 10−9 A cm−2. During long-term exposure of samples to 0.9 % NaCl solution, it was found that coating reduced the rate of corrosion degradation of samples from 1.5 to 80 times compared to an unprotected Mg-HA composite and sintered magnesium. Mg-HA composites treated with PEO exhibit potential application as bioactive and biodegradable materials for orthopedic implants and fixation devices.

Experimental study on effect of elastic-rigid composite boundary on shockwave from cavitation bubble collapse

Understanding the mechanisms behind the cavitation erosion resistance of elastic materials is the basis for the development of new cavitation erosion resistance materials. This paper employs underwater low-voltage discharge to induce cavitation bubble, combined with high-speed photography, shadowgraph methods, and transient pressure measurement systems to experimentally investigate the evolution and intensity of shockwave from bubble collapse near elastic-rigid composite boundary. Under the condition of constant elastic material thickness, with the bubble–wall distance increasing, shockwave shape evolves from multi-layers to single-layer. The peak pressure of the shockwave shows a trend of decreasing, then increasing, and finally stabilizing with increase in the bubble–wall distance. Furthermore, it was found that the elastic-rigid composite boundary causes the shockwave to reflect twice. As the material thickness increases, the intensity of the first reflected shockwave from the elastic surface decreases initially, then increases, and eventually stabilizes. However, that of the second reflected shockwave decreases. The total energy of the two reflections at the elastic interface is less than 4% of the mechanical energy of the bubble at its maximum volume. Finally, after the energy dissipation by the two reflections and material deformation, the elastic layer substrate withstands over 70% of the total mechanical energy of the cavitation bubble. There is an optimal elastic material thickness to minimize the shockwave load on the elastic layer substrate under the condition that the elastic-rigid composite boundary does not affect the evolution of cavitation bubble shape. These findings are significant for understanding bubble dynamics near elastic-rigid composite boundaries and provide theoretical support for developing cavitation erosion-resistant materials in engineering.

Advanced corrosion-resistant materials for enhanced nuclear fuel performance: A conceptual review of innovations in fuel cladding against molten salt degradation

The increasing demand for efficient and sustainable nuclear power has led to the development of advanced corrosion-resistant materials that can significantly enhance nuclear fuel performance. This conceptual review focuses on the innovations in fuel cladding materials designed to resist degradation in molten salt environments, which are crucial for advanced nuclear reactors like molten salt reactors (MSRs). Fuel cladding serves as a critical barrier between the nuclear fuel and the reactor environment, and its ability to withstand extreme temperatures and corrosive conditions is essential for safe and efficient reactor operation. Recent advancements in materials science have introduced novel alloys and coatings that demonstrate superior corrosion resistance in molten salts, which are used as both coolants and fuel solvents in MSRs. These innovations include high-temperature nickel-based alloys, refractory metals, and ceramic coatings, which are engineered to reduce the effects of molten salt corrosion, such as oxidation, pitting, and embrittlement. By enhancing the durability of fuel cladding, these materials contribute to improved fuel performance, longer reactor lifespans, and increased safety. This review explores key developments in corrosion-resistant materials, emphasizing the mechanisms by which these materials mitigate molten salt degradation. Additionally, it highlights the challenges associated with material selection, fabrication, and long-term performance in the highly corrosive environments of advanced nuclear reactors. Ongoing research into these materials offers promising avenues for the future of nuclear energy, particularly in addressing the limitations of current fuel cladding technologies. In conclusion, the use of advanced corrosion-resistant materials represents a significant step toward enhancing the performance and safety of nuclear fuel, ensuring the viability of MSRs and other advanced reactor designs. Continued innovation in this field is essential for the future of nuclear power.

Electrochemical corrosion behavior and passive film properties of Fe2Ni2CrV0.5Nbx (x=0.2, 0.4, 0.6, 0.8) eutectic high-entropy alloy coating prepared by laser cladding

The phase composition, microstructure morphology, and corrosion behavior of Fe2Ni2CrV0.5Nbx (x = 0.2, 0.4, 0.6, 0.8) eutectic high-entropy alloy (EHEA) coatings produced via laser cladding were investigated. The research delved into discerning the phase structures and microstructural variations of the EHEA coatings concerning differing Nb compositions. The findings highlighted a direct correlation between Nb content and the volume fraction of the eutectic structure, specifically the FCC/Laves phases. Electrochemical evaluations, including diverse tests such as potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic polarization, Mott-Schottky measurements, and X-ray photoelectron spectroscopy, revealed distinct corrosion behaviors among the EHEA variants. Notably, the Fe2Ni2CrV0.5Nb0.2 coating exhibited relatively superior corrosion resistance compared with Fe2Ni2CrV0.5Nbx (x = 0.4,0.6,0.8) coatings, attributed to its lower corrosion current density (Icorr) and the formation of a thicker passive film with prolonged passivation duration. Conversely, the Fe2Ni2CrV0.5Nb0.8 coating, characterized by increased eutectic structures and grain boundary density, yielded a thicker yet non-uniform passive film with higher vacancy defects. This comprehensive exploration into the corrosion behavior and passive film properties of these EHEA coatings provides a reference for designing materials that hold promising implications for future corrosion-resistant material development in industrial parts repair applications.

Investigation of the corrosion behavior of 29NC alloy in LiCl-KCl melt at 500 oC depending on the content of Li2O and LiOH from 0 to 2 mol. %

Molten chloride salt electrolytes are promising for use as a working medium for the implementation of high-temperature technologies. Alkali metal chlorides are an aggressive environment in relation to structural materials. One of the possible methods of reducing the corrosion damage of a structural material is the method of oxygen passivation of the surface of a metal or alloy by introducing a certain amount of oxygen-containing additives into the melt. The article considers the effect of oxygen-containing impurities (lithium oxide and lithium hydroxide) on the corrosive behavior of a metal material — an alloy of the composition iron–cobalt–nickel. To assess the corrosion resistance of materials, gravimetric analysis, micro-X-ray spectral analysis (XRSA) of the surface and cross-section sections, and X-ray phase analysis (XRF) of the sample surface were used. The dependences of the corrosion rate of the material on the concentration of oxygen-containing additives Li2O and LiOH are presented. Based on the data set of gravimetric, MRSA and XRF data, it was found that 29NC alloy samples in the LiCl–KCl–nLi2O salt melt are not susceptible to corrosion, but in the LiCl–KCl–nLiOH melt, the speed of the 29NC alloy increases significantly due to the interaction of the LiOH additive with the most electronegative component of the alloy — iron.