Low Corrosion Research Articles

Biomass residues purification: elimination of oxygen from oxolane and its monomethylated derivatives through hydrodeoxygenation process

The persistent global demand of fossil fuels has spurred significant interest in the invention of new renewable energy sources to replace finite, non-renewable fossil fuels. Among these sustainable energy options, biomass stands out as a promising candidate as environment friendly alternative fuel. However, the organic compounds found in biomass contain a high oxygen content, leading to several undesirable characteristics in biofuels, including low energy density, less stability, high viscosity, and corrosion. Consequently, researchers have devised various upgrading techniques, with a particular emphasis on the hydrodeoxygenation (HDO) process, to enhance the quality of biofuel. In this report, we investigated the treatment of Oxolane, 2-Methyloxolane and 3-Methyloxolane via adsorption and catalytic hydrogenolysis (HDL) processes. These processes aim to remove the oxygen heteroatom from these compounds, ultimately achieving the desired purity levels. To elucidate the underlying mechanisms, we employed the B3LYP/6–31G(d) and LanL2DZ/6–31G(d) methods of DFT for reaction without or with catalysts. The hydrogenolysis, in the presence and absence of a catalyst is carried at a temperature and pressure of 523 K and 40 bar, respectively. We meticulously analyzed the variations in geometries, thermodynamic and kinetic properties to gain insights into the whole processes. For each molecule, the sequence involves ring opening of C–O bond, followed by the elimination of a water molecule. The first hydrogenolysis step yields an alcohol as a reaction intermediate, while the second hydrogenolysis step results in the formation of an alkane. Geometric parameters showed the increased reactivity of Oxolane and its derivatives in the presence of tungsten disulphide (WS2) catalyst. Chemical potential indicates the charge transfer occurred in all, and the highest charge transfer is observed in Oxolane in the presence of tungsten disulphide (WS2) catalyst.

Investigating the effect of Zr content on electrochemical and tribological properties of newly developed near β-type Ti-alloys (Ti–25Nb-xZr) for biomedical applications

In order to create alloys with exceptional properties for orthopedic uses, this study focuses on the impact of zirconium (Zr) content on the structural, electrochemical, and tribological qualities of nanostructured Ti–25Nb-xZr [x = 5, 10, 15, 20, 25, and 30 atomic (at.) %] alloys. The structural evolution was investigated using XRD and SEM techniques. The mechanical characteristics of the produced alloys, including Vickers hardness and Young's modulus, were measured. In addition, the corrosion tests were performed using the OCP, EIS, and PD methods in Ringer's solution within the independent pH range at 37 °C. A ball-on-disc tribometer was used to investigate the tribological behavior of the alloys under various loads and wet conditions using the Ringer solution. It has been verified that Zr content (at. %) in the alloys had an impact on their morphologies, structural evolution, and mechanical characteristics. According to the morphological analysis, the particle and crystallite size decreases with increasing Zr content. Young's modulus and Vickers hardness show the same tendency. The EIS data demonstrated that a single passive film formed on the alloy surfaces, and the addition of Zr enhanced the corrosion resistance of the passive films. The polarization curves demonstrate that the alloys had low corrosion current densities and large passive areas without the passive films disintegrating. Likewise, the inclusion of Zr resulted in a reduction in the corrosion and passive current density values. All of these results suggested that the titanium alloys exhibit a more noble electrochemical activity caused by Zr. From the tribological perspective, it was found that the friction coefficient of the alloys reduced with increasing Zr content.

Experimental Study of the Corrosive and Biocompatible Properties of Bioresorbable Mg-Ca-Zn Alloy Implants

Introduction. Magnesium and its alloys are used as biodegradable bone implants due to their high biocompatibility, however, the problem of use is rapid biodegradation with loss of strength.The purpose of the study. Experimental evaluation of bioresorbable Mg-Ca-Zn alloy implants in vitro and in bone tissue in vivo, in order to determine the optimal rate of biodegradation, biocompatibility and reparative response of bone tissue.Materials and methods. Samples from the obtained Mg-Ca-Zn alloy were coated in a microarc oxidation bath (MDO), and to further determine the optimal phase composition and surface properties, the samples were kept in an electrolyte. The biodegradation of implants was assessed by the loss of mass of samples in vitro, and the release of gas into bone tissue in vivo, and the biocompatibility and reparative response of bone tissue density.Results. All Mg-Ca-Zn coated samples show reduced weight loss compared to the uncoated sample. Magnesium samples with a 20-minute exposure in electrolyte, in the context of its application in anatomically unloaded areas, showed the optimal rate of biodegradation, biocompatibility and reparative response of bone tissue.Discussion. In our study using the microarc oxidation for control the corrosion resistance samples of magnesium alloy shows good biocompatibility and low corrosion rate. We found 5-fold increase in corrosion resistance in coated implants, compared with uncoated samples.Сonclusion. The results of an experimental evaluation of bioresorbable Mg-Ca-Zn alloy implants in vitro and in bone tissue in vivo showed that Mg-Ca-Zn coated samples demonstrate low weight loss during biodegradation, with minimal gas release into the bone.

MXene‐CeO2@PDA Synergistically Enhanced Anticorrosion of Waterborne Epoxy Coating

AbstractDeveloping ecofriendly anticorrosion coating has great demand for marine protection. Incorporation of nontoxic inorganic fillers into waterborne epoxy (WEP) coating shows tremendous potential for enhancing corrosion resistance. However, the application of MXene/WEP coating is limited by the poor dispersion of MXene in WEP and insufficient corrosion resistance. Herein, a polydopamine (PDA) modified MXene‐CeO2@PDA (MCP) filler is constructed by a combination of CeO2 with MXene and embedded into WEP to form ecofriendly anticorrosion MCP/WEP coating. Dispersion of MXene in WEP is improved by the introduction of CeO2 and PDA modification. Benefiting from the synergy of the physical labyrinth effect of MXene and the chemical inhibition effect of CeO2, MCP/WEP coating exhibits remarkable anticorrosion behavior in 3.5 wt% NaCl solution with a low corrosion rate (CR) of 4.48 × 10−6 mpy, which is three orders of magnitude lower than that of blank WEP (4.78 × 10−3 mpy). Moreover, MCP/WEP presents long‐term and stable corrosion protection for over 30 days. The results reveal the incorporation of MCP significantly promotes the anticorrosion performance of WEP.

Enhancing the strength and structure of Al–Si alloys for biomedical applications through the addition of Sr and Zr grain refiners on secondary AlSi7Mg aluminum alloys

The biomedical industry needs Aluminium alloys with superior corrosion resistance properties for limited applications. The use of Al–Si alloys is often seen as non-bio-compatible alloys due to their lower corrosion resistance properties. The present study aims to enhance the properties of such Al–Si alloys through modification of the Si phases with Strontium (Sr) and Zirconium (Zr) through grain size modification. The present study included the preparation of an Al–Si aluminium alloy utilizing a mixture of different scraps. To refine the grain structure, variable concentrations of Sr and Zr grain refiners were added to the alloy using a stir-casting process. The qualities, including porosity, density, tensile strength, yield strength, and hardness, were assessed according to ASTM standards. The grain size and distribution of intermetallic compounds were investigated by performing a microstructural examination using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, to determine the impact of Sr and Zr. The results demonstrate that the inclusion of Sr and Zr grain refiners effectively enhances the grain structure, leading to enhanced microstructural and mechanical properties of the secondary aluminium alloys. This study contributes valuable insights into optimizing the grain refining process for secondary aluminum alloys, offering potential advancements in their industrial applications, particularly in the biomedical industry, where the demand for high-performance biocompatible aluminum materials is steadily increasing.

S-NiSe/HG Nanocomposites with Balanced Dielectric Loss Encapsulated in Room-Temperature Self-Healing Polyurethane for Microwave Absorption and Corrosion Protection.

Exploring anticorrosion electromagnetic wave (EMW) absorbing materials in harsh conditions remains a challenge. Herein, S-NiSe/HG nanocomposites encapsulated in room-temperature self-healing polyurethane (S-NiSe/HG/SPU) were exploited as superior anticorrosion EMW absorbing materials. A dual-defect engineering collaborative Schottky interface construction endows S-NiSe/HG with a high vacancy concentration, abundant defects, and moderate conductivity. These structural merits synergistically balance dielectric loss by enhancing dipole-interface polarization loss and optimizing conduction loss. As a result, S-NiSe/HG demonstrates the optimal EMW absorption performance with a minimum reflection loss (RLmin) of -54.8 dB and an adequate absorption bandwidth (EAB) of 7.1 GHz. Besides, S-NiSe/HG/SPU combines the maze effect of S-NiSe/HG with the active repair capability of SPU, thereby providing long-term corrosion resistance for the Mg alloy. Even under corrosion for 10 days, S-NiSe/HG/SPU affords a low corrosion current density (1.3 × 10-5 A) and high charge transfer resistance (3796 Ω cm2). Overall, this work provides valuable insights for in-depth exploration of dielectric loss and development of multifunctional EMW-absorbing materials.

Influences of flame remelting and WC-Co addition on microstructure, mechanical properties and corrosion behavior of NiCrBSi coatings manufactured via HVOF process

We investigated the microstructures, mechanical properties, and corrosion behavior of NiCrBSi coatings upon the addition of the WC-Co powder in various amounts (0, 5, 10, 15, and 20 wt%) using the high velocity oxy-fuel process on low-carbon steel. Additionally, flame remelting was performed at 1100 °C for 1 min following thermal spraying of the coatings. The microstructures of the coatings were examined using X-ray diffractometry and scanning electron microscopy, and the mechanical properties of the coatings were assessed via Vickers microhardness and ball-on-disk tests. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization testing in a 20 vol.% sulfuric acid solution. The results demonstrated that an increase in the WC-Co amount enhanced the hardness and wear resistance of the coatings. For 10–20 wt% WC-Co addition, small cracks were observed in the as-sprayed coatings owing to the heat applied during thermal spraying and rapid cooling, respectively. The presence of porosity directly affects the corrosion behavior of the coatings. Flame remelting led to better cohesion and the distribution of the γ-Ni and WC phases, reducing microdefects, such as pores and cracks. The mechanical properties of the coatings improved as the WC-Co amount increased after flame remelting, resulting in the formation of intermetallic compounds (FeB, CoSi2, and Ni2Si) along with the WC phase. The flame-remelted NiCrBSi/ 10 wt% WC-Co coating demonstrated high hardness and low wear and corrosion rates (1072.26 HV, 4.8 × 10−6 mm3/m, and 0.560 mm/year, respectively). Therefore, WC-Co addition and the flame remelting process significantly enhanced the properties of NiCrBSi coatings. This study highlights the substantial contributions of WC-Co addition and the flame remelting process in enhancing the mechanical properties and corrosion resistance of NiCrBSi coatings. These findings offer valuable insights for optimizing the performance of commercially available coatings in various real-world applications in maintaining power plants and industrial components like high-pressure pump piston rods, acid-resistant pumps in oil refineries.

Exploring the effect of chlorhexidine concentration on the biocorrosion behavior of Ti6Al4V for dental implants.

Corrosion of dental implants is one of the most critical factors in the failure of implant treatments. Generally, corrosion depends on the type of material used in implants and the chemical composition of the oral environment. Due to the antibacterial activities, mouthwashes and chlorhexidine gels are often used after implant surgery. Ti6Al4V is commonly used in manufacturing dental implants. The present study aims to investigate the corrosion behavior of the Ti6Al4V alloy under different concentrations of chlorhexidine (0.12%, 0.2%,and 2%) during 2- and 24-h immersion. This way corrosion may be minimized while obtaining an antibacterial environment around the implant. In this regard, the electrochemical behavior of the specimens was investigated using polarization and impedance tests, and then their morphology, cross-section and nano-tribological behavior were evaluated using atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and nano-scratch test. The results show that using chlorhexidine solution with a concentration of 0.12% could yield a lower corrosion rate and material loss after implant surgery. RESEARCH HIGHLIGHTS: Open circuit potential values increase with immersion time, which suggests multistage passivation of the surface during immersion in chlorhexidine. Specimens in 0.12% chlorhexidine show improved thermodynamic corrosion resistance. Nano-scratch testing demonstrates higher scratch resistance for specimens in 0.12% chlorhexidine solution after 2-h immersion. Higher chlorhexidine concentration than 0.12% and longer immersion times decrease the resistance of the formed passive layer.

The investigation on properties of Ti- 5Si and Ti- 5Nb implant alloys coated by bioactive based composite coating

Titanium (Ti) alloys are widely utilized in orthopedics owing to their excellent mechanical properties and biocompatibility. To improve their resistance to corrosion and ion release properties, substrates of Ti alloy have been produced employing powder metallurgy by adding alloying elements (Si and Nb) at 5 wt% along with CP-Ti. Two torch flame sprays have been utilized for coating the Ti-5Nb and Ti-5Si alloys with two kinds of nanocoating: HAp+25%SiC (type-A) and ZSM5 + 25%ZrO2 (type-B). These nanocoating combinations represented bioactive and bioinert to combine the biological and mechanical properties of the implant surface. Different tests and characterization techniques have been carried out, including SEM, XRD, AFM, AAS, hardness, adhesion strength, and corrosion resistance. The results manifested that the coatings (types A and B) improved the properties of Ti alloys; however, ZSM5 + 25%ZrO2 has better properties than type-A in terms of less porosity, higher crystallinity%, higher hardness, higher adhesion strength, lower corrosion rate, and less Ti ions release. Comparing the results of the two Ti alloys, Ti-5Si has higher hardness, corrosion resistance, and less ionic release than the Ti-5Nb alloy. Hence, the Ti-5Si coated by ZSM5 + 25%ZrO2 (B coated Ti-5Si) is the best sample in this study.

Assessing the role of friction stir welding tool shoulder profile and parameters on mechanical performance of Al5083 weld joints pre- and post-corrosion exposure

Al5083 alloy sheets were joined by friction stir welding (FSW) by using three different tools having different shoulder profiles (flat, concave and convex) at three different tool rotational speeds. From the cross-sectional microstructures, weld joints obtained at 1120 rpm with three different shoulder profiles were observed as defect free. XRD analysis confirms the development of texture that was dominated with close packed planes. The weld joint mechanical performance was assessed by conducting tensile tests before and after exposing them to 3.5% NaCl solution for 24 h. Combination of concave shoulder profile with 1120 rpm tool rotational speed has given higher strength in the weld joint, compared with base alloy and the other weld joints. The weld joints produced by using flat and concave shoulder profiles exhibited higher mechanical strength even after corrosion attack compared with the base alloy. From the potentiodynamic polarization studies, the three defect free weld joints (processed at 1120 rpm) were measured with lower corrosion current density. The results demonstrate the promising role of FSW to retain the strength against the corrosion initiated mechanical failure of Al5083 alloy by selecting appropriate combination of the shoulder profile and welding parameters.

Effect of Si addition on microstructure and performance of a biomedical Ti-Nb-Zr-Ta alloy prepared via powder hot extrusion

In this study, TNZT-xSi ((Ti53Nb35Zr7Ta5)100-xSix, x=0, 1.4, 2.3, wt.%) alloys are prepared by powder hot extrusion. The effect of Si addition on microstructure, mechanical properties, corrosion resistance and in vitro apatite formation ability of TNZT-xSi alloys is investigated. The as-extruded TNZT alloy mainly consists of elongated BCC grains. The addition of Si leads to the precipitation of fine (Ti, Zr)2Si (S2) particles from the BCC matrix. With the increase of Si content, the volume fraction of recrystallized grains rises significantly, and the microstructure of extruded alloys tends to transform from elongated to equiaxed grains. It’s indicated that the introduction of S2 particles activates the dynamic recrystallization process during hot extrusion and results in an obvious reduction in the overall grain size. Compared with the TNZT-0Si base alloy, the tensile strength of TNZT-2.3Si alloy is improved from 726MPa to 983MPa, with the elongation declining from 28.0% to 9.5%. The TNZT-xSi alloys exhibit higher corrosion potential (Ecorr) and lower corrosion current density (Icorr) than Ti-6Al-4V alloy in simulated body fluid, due to the formation of more stable oxides such as Nb2O5, ZrO2 and Ta2O5. Furthermore, TNZT-xSi alloys have apatite formation ability superior to Ti-6Al-4V. These results suggest that TNZT-xSi alloys may have the potential as a biomaterial for implant applications.

Mitigation of bio-corrosion characteristics of coronary artery stent by optimising fs-laser micromachining parameters

Cardiovascular diseases, particularly coronary artery disease, pose big challenges to human life. Deployment of the stent is a preferable treatment for the above-mentioned disease. However, stents are usually made up of shape memory alloy called Nitinol. The poorer surface finish on the machined nitinol stents accelerates the migration of Nickel ions from the implanted nitinol stent, which is considered toxic and can lead to stenosis. The current study deals with controlling surface quality by minimising surface roughness and improving corrosion resistance. Femtosecond laser (fs-laser 10−15 s) micromachining was employed to machine the Nitinol surface to achieve sub-micron surface roughness. The Grey relational analysis (GRA)-coupled design of the experimental technique was implemented to determine optimal levels of four micromachining parameters (laser power, pulse frequency, scanning speed, and scanning pattern) varied at three levels to achieve minimum surface roughness and to maximise the volume ablation. The results show that to yield minimum surface roughness and maximum volume ablation, laser power and scanning speed are in a higher range. In contrast, the pulse frequency is lower, and the scanning pattern is in a zig-zag manner. ANOVA results manifest that scanning speed is the predominant factor in minimising surface roughness, followed by pulse frequency. Furthermore, the corrosion behaviour of the machined nitinol specimens was evaluated, and the results show that specimens with lower surface roughness had lower corrosion rates.

The Calcium Gluconate Filled Epoxy Waterborne Primer Coating for Marine Application

The synthesis of corrosion protection in the waterborne epoxy primer coating, which included calcium gluconate (CG), was synthesized. Various compositions of CG, ranging from 0 to 8 grams were applied to the carbon steel substrate using this water-based epoxy coating. The investigations included FTIR characterization, Tafel plot polarization, immersion, adhesion, and hardness tests. The presence of CG at 2868.88 cm-1, corresponding to calcium ion (Ca2+), was confirmed by the FTIR result, while the epoxy functional group was detected at 1506 cm-1. Furthermore, it was observed that the immersion test, hardness test, and adhesion test revealed that the highest formulation for corrosion inhibition was 8 g of CG, which also exhibited a lower corrosion rate of 0.262 mmpy, improved mechanical properties (4H), and 0 % area removed. The presence of CG, which facilitated interaction with the epoxy resin through coordination between gluconate ions and Ca2+ ions, was believed to be responsible for increasing the concentration of dissolved Ca2+ ions in the solution. This, in turn, enhanced the formation of Ca(OH)2 on the surface of the aluminium alloy, leading to corrosion inhibition. Ultimately, the utilization of CG as an anti-corrosive pigment resulted in a reduction of corrosive properties and an enhancement of mechanical properties in waterborne primer coatings.

Influence of aging treatment on corrosion behavior of extruded 2195 Al−Li alloy

The 2195 Al-Li alloy was processed by under-aging (UA), peak-aging (PA), double-aging (DA) and retrogression re-aging (RRA) treatments, and the microstructure, intergranular corrosion (IGC), exfoliation corrosion (EXCO) and stress corrosion cracking (SCC) behaviors were observed and discussed. The results show that the sequence of IGC and EXCO resistance is: RRA > UA > DA > PA. The low corrosion resistance of PA and UA is mainly caused by the continuous precipitation of T1 phases at grain boundaries to form continuous corrosion channels, while the interruption of corrosion channels caused by coarse and discontinuous T1 phases and wider precipitate free zone is the reason for the best corrosion resistance of RRA. The RRA alloy exhibits the best SCC resistance, and the order of SCC resistance is: RRA > DA > UA > PA. The discontinuous precipitation of intergranular T1 phases promotes the propagation of corrosion cracks across grain boundaries, thereby improving the SCC resistance.

Using green corrosion inhibitor to reduce maintenance cost for carbon steel saline water storage systems in the oil industry

Abstract Carbon steel has long been used in storing the saline water that results from oil washing in the oil industry. However, a high corrosion rate is reported, resulting in significant economic losses for oil companies. In the Middle East oil field, the temperature touches 50⁰C in Summer, causing increasing in corrosion rate for saline water steel storage tanks and pipes. In the present work, abundantly available wheat straw was used to prepare a cost-effective silicate inhibitor. The high inhibition efficiency of up to 94 % decreased the corrosion rate from severe corrosion for no-inhibitor specimen to close to low corrosion category for optimum inhibitor concentration specimen. The mechanism of the inhibition effect is the formation of a chemically adsorbed layer on the steel surface, which is successfully described by Langmuir isotherm. Additionally, at high concentrations of nano-silica, complex aggregates might form and be physically adsorbed on the surface of steel above the chemically adsorbed nano-silicate monolayer.

Synthesis of betaine surfactant and its application in microemulsion flushing fluid

In order to effectively remove the oil-based drilling fluid and oil mud cake attached to the wellbore, improve the cementation environment of the second interface and improve the quality of cementing, a betaine-type zwitterionic surfactant (OASB) was synthesized in this study. The structure of OASB was characterized by IR and 1H NMR. The interfacial tension of OASB solution with different concentration was measured. A microemulsion cementing flushing fluid (MFF) was prepared with OASB mixed with Tween 80 as surfactant, n-octanol as cosurfactant, kerosene as oil phase and deionized water as water phase. The stability, particle size, rheology, corrosivity and wettability of MFF were analyzed and tested. The flushing effect of MFF on oil-based drilling fluid and oil mud cake was evaluated, and the changes in bonding strength of the second interface of cementing before and after flushing was compared and analyzed. The results revealed that MFF had good temperature, salt, acid and alkali resistance and low corrosion ability. The apparent viscosity was 25 ∼ 80 mPa·s in 20 ∼ 120 °C and had good rheological properties. The excellent wettability reversal ability of MFF was beneficial for removing oil-based drilling fluid and oil mud cake, with a flushing efficiency of over 90%. After MFF flushing, the bonding strength of the second interface of cementing was significantly improved. The SEM and elemental analysis showed that MFF had a more thorough flushing of oil mud cake, and the bonding structure between the cement stone and the second interface was denser.

Enrichment of electrogenic microbes on surface-modified stainless steel 304L for rapid start-up of microbial electrochemical sensors

Stainless steel (SS) 304L, a cost-effective and mechanically robust material, is widely used in microbial electrochemical systems as an anode due to its versatility. However, poor biocompatibility and low corrosion resistance limit its potential. This study explores rapid SS surface modification techniques to enhance the sensitivity of microbial electrochemical sensors. Four coatings, namely electroreduction, carbon-coated, flame oxidised, and graphene-coated, were applied to SS electrodes. Surface morphology and characteristics were examined through FESEM-EDX and Raman profiling. The biosensor start-up and microbial enrichment demonstrated an exponential increase in current density, with carbon-based electrodes outperforming iron-based ones. The modified electrodes exhibited enhanced microbial-electrode interactions, evident in altered electrode potential. Starvation and recovery tests revealed distinct patterns, with carbon-coated electrodes showcasing rapid recovery. The air-in-chamber test indicated immediate loss and subsequent recovery of microbial activities upon water circulation. Surface modification significantly influenced the microbial response, with carbon-based coatings demonstrating superior performance. This study provides valuable insights into SS surface modification for improving microbial electrochemical sensor sensitivity, holding promise for diverse applications in environmental monitoring and biosensing.

Advancements in Multilayer Coatings on Aluminium Alloy-Based Bipolar Plates for PEMFC Application

Fuel cells represent a revolutionary and sustainable approach to energy conversion, offering a clean alternative to traditional combustion-based power generation. These electrochemical devices convert the chemical energy of a fuel, typically hydrogen, directly into electricity. The fundamental working principle involves the electrochemical reaction between hydrogen and oxygen, facilitated by a catalyst, to produce electricity, water, and heat as byproducts in Proton Exchange Membrane (PEMFC). This strategic use of aluminum (Al) alloy for Bipolar plates (Bp) aligns with the industry's commitment to advancing materials and design methodologies, ultimately promoting the optimization of fuel cell technology in terms of performance, durability, and economic feasibility. This comprehensive review investigates recent progress in the development of multilayer coatings tailored for Al alloy-Bp in PEMFCs. Al alloys are a preferred substrate material due to their cost-effectiveness, lightweight nature, and high thermal conductivity. However, challenges such as corrosion, electrical conductivity, and interfacial contact resistance have spurred extensive research into innovative coating solutions. The review critically examines various coating materials, deposition techniques, and performance evaluation methods aimed at addressing the challenges associated with al alloy Bp. Special emphasis is placed on corrosion-resistant coatings, conductive layers, and interfacial modifiers. The assessment encompasses both established technologies and cutting-edge approaches, including nanocomposite coatings, self-healing materials, and advanced characterization methods. By synthesizing and analyzing existing literature, this review provides a comprehensive overview for researchers, engineers, and policymakers involved in advancing PEMFC technology. The findings underscore the crucial role of multilayer coatings in augmenting the performance and longevity of al alloy-based Bp, offering valuable insights to guide further research and development in the pursuit of efficient and durable fuel cell systems. In comparing the aluminum grades Al-356, Al-5052, Al-6061, and Al-7075, it is observed that Al 5052 exhibits lower corrosion density, providing greater efficiency compared to other aluminum grades. In the case of Al 356, the potentiostatic result yields a lower value than that of other aluminum grades. Consequently, these findings suggest a tendency for favorable corrosion resistance and electrodeposition in both Al 5052 and Al 356, making them noteworthy choices in applications requiring these particular material characteristics.

Mechanical Properties and In Vitro Corrosion Behaviors of Biodegradable Magnesium Alloy Suture Anchors

Biodegradable suture anchors based on Mg-Nd-Zn-Zr alloy were developed for ligament-to-bone fixation in rotator cuff surgeries. The Mg alloy anchors were designed with structural features of narrow tooth and wide tooth, and simulated through finite element analysis (FEA). Meanwhile, the corrosion behaviors of the Mg alloy anchors were studied by immersion test and the mechanical properties were investigated by measuring the maximum torque and pull-out force. The simulation result showed that the wide-tooth anchor exhibited more a uniform stress distribution and lower shear stress in the torsion process, suggesting a satisfactory torsional resistance of this structure. Meanwhile, the wide-tooth anchor exhibited a lower Von-Mises stress after applying the same pull-out force in the simulation, indicating a higher resistance to pull-out failure of the anchor. The result of the immersion test indicated that the wide-tooth anchor exhibited a slightly slower corrosion rate in Hank’s solution after 14-day immersion, which was beneficial to enhance the structural and mechanical stability of the biodegradable suture anchor. Furthermore, the results of the mechanical properties test demonstrated that the wide-tooth anchor showed superior performance with higher maximum torques and axial pull-out forces before and after corrosion. More importantly, the axial pull-out force and maximum torque for the wide-tooth anchor decreased by 5.86% and 8.64% after corrosion, which were significantly less than those for the narrow-tooth anchor. Therefore, the wide-tooth suture anchor with lower corrosion rate, higher mechanical properties and structural stability is a promising candidate for ligament-bone fixation in the repair of rotator cuff injuries.

Anti-corrosion effect of chitin and chitosan nanoparticles in epoxy coatings

In recent years, the incorporation of nanoparticles and corrosion inhibitors into epoxy coatings has become increasingly important in order to address the growing demand for advanced anti-corrosion coatings. In this study, various amounts of extracted chitin and chitosan nanoparticles from shrimp ranging from 0 to 3% wt. were added to an epoxy coating. The zeta potential of particles and scanning electron microscope were applied to determine average particle size and distribution of particle in the epoxy coating. Thermal stability, adhesion properties and corrosion behavior of reinforced coating were investigated. The epoxy coating with a 2%wt chitin additive showed a more uniform distribution. Fourier transform infrared spectrometry and the thermogravimetric analysis test (TGA) illustrated that the addition of chitin and chitosan additives lead to chemical changes in the structure and improve the thermal stability of epoxy coatings. The addition of 2%wt chitin nanoparticles improved the mechanical properties of the coatings, particularly the adhesion resistance. Corrosion testing revealed that the epoxy coating containing 2% chitin and chitosan nanoparticles exhibited a low corrosion rate, high load transfer resistance, and a double layer capacity when exposed to a 3.5% NaCl solution.