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The microdefects of polylactic acid coating on medical magnesium alloy significantly reduce the corrosion resistance of magnesium alloy components, which is difficult to detect by conventional non-destructive testing methods. To address this issue, a nonlinear ultrasonic detection technique is proposed to detect polylactic acid coated specimens with different microdefects. Through electrochemical corrosion tests and nonlinear ultrasonic tests, it has been observed that the ultrasonic nonlinear coefficient $\beta $ β increases with the decrease of corrosion resistance. Furthermore, the microscopic test results show that the bubble microdefects caused by the uneven solidification of polylactic acid coating are the main source of ultrasonic nonlinearity. With the increase of microdefects, the $\beta $ β value of the specimen will increase. The correlation analysis reveals a strong relationship between β and parameters related to coating uniform coverage and electrochemical corrosion resistance, and the lowest correlation coefficient is 0.78. Therefore, using nonlinear ultrasonic non-destructive testing technology can effectively detect the microdefects of polylactic acid coating on magnesium alloys, and it also has a certain guiding role in the biological application of magnesium alloys. [ABSTRACT FROM AUTHOR]

The effect of hot rolling on the microstructure, mechanical, and corrosion properties of the magnesium alloy 96 wt% Mg–2.3 wt% Zn–0.7 wt% Ca–1 wt% Mn was studied. After heat treatment, the original plates of an as-cast alloy were rolled from a 7 mm thickness to a 0.2 mm thickness at two temperatures—300 or 400 °C. It has been established that increasing the rolling temperature from 300 to 400 °C increases the fraction of recrystallized grains in the microstructure and after rolling at 400 °C, the microstructure is fully recrystallized. The best strength–ductility balance of the alloy was obtained after rolling at 300 °C, with a high total percentage reduction of 93–97%: the yield stress, the ultimate tensile strength, and the elongation averaged at 285 MPa, 310 MPa, and 5%, respectively. The alloy after rolling, annealed at 400 °C, shows improved ductility but lower strength: the yield stress, the ultimate tensile strength, and the elongation were 200 MPa, 260 MPa, and 17%, respectively. The strong dependence of corrosion resistance on respect to rolling direction is observed, which can be reduced after heat treatment. The as-rolled alloy and the heat-treated alloy had low corrosion rates in Hanks' solution of 0.54 and 0.19 mm/year, respectively. [ABSTRACT FROM AUTHOR]

The impact of fluoride-based coatings on the microstructure and mechanical integrity of extruded Mg-1.0Zn-0.3Zr-1.0Y-2.0Sn alloys was assessed utilizing optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), immersion testing, electrochemical analysis, and tensile testing. It was observed that the magnesium alloys could be immersed in hydrofluoric acid (HF) for varying durations to achieve coatings of distinct thicknesses, with the coating thickness stabilizing at approximately 8 μm after a 48 h immersion period. The application of the fluoride coating significantly enhanced the corrosion resistance of the alloys, with a corrosion rate (CRH) of 0.13 ± 0.012 mm/y. Upon a 20-day immersion in simulated body fluid (SBF), the degradation rates of the yield strength (YS), tensile strength (UTS), and elongation (EL) for the cast alloys were recorded as 62%, 59%, and 64%, respectively. For the extruded alloys, these rates escalated to 77%, 76%, and 95%. In contrast, the fluorine-coated alloys exhibited significantly lower degradation rates of 28%, 23%, and 39% after a 25-day immersion in SBF. Upon extrusion, the specimens exhibit a diminished corrosion resistance and a more substantial decline in mechanical properties compared to their as-cast state. Upon the application of the coating, there is a discernible reduction in the rate of mechanical property degradation observed in the specimens. This indicates that the fluorinated coating can mitigate the corrosion rate and enhance the corrosion resistance of magnesium alloys. [ABSTRACT FROM AUTHOR]

In this study, we utilized Selective Laser Melting (SLM) technology to fabricate a magnesium alloy, and subsequently subject it to micro-arc oxidation treatment. We analyzed and compared the microstructure, elemental distribution, wetting angle, and corrosion resistance of the SLM magnesium alloy both before and after the micro-arc oxidation process. The findings indicate that the SLM magnesium alloy exhibits surface porosity defects ranging from 2% to 3.2%, which significantly influence the morphology and functionality of the resulting film layer formed during the micro-arc oxidation process. These defects manifest as pores on the surface, leading to an uneven distribution of micropores with varying sizes across the layer. The surface roughness of the 3D-printed magnesium alloy exhibits a high roughness value of 180 nanometers. The phosphorus (P) content is lower within the film layer compared to the surface, suggesting that the Mg3(PO4)2 phase predominantly resides on the surface, whereas the interior is primarily composed of MgO. The micro-arc oxidation process enhances the hydrophilicity and corrosion resistance of the SLM magnesium alloy, thereby potentially endowing it with bioactivity. Additionally, the increased surface roughness post-treatment promotes cell proliferation. However, certain inherent defects present in the SLM magnesium alloy samples negatively impact the improvement of their corrosion resistance. [ABSTRACT FROM AUTHOR]

After micro-arc oxidation, the surface properties of AZ31 magnesium alloy have been improved. However, micro-arc oxidation treatment leads to high insulation, which limits its application in electronic devices. To increase conductivity, a conductive coating was developed by adding multi-walled carbon nanotubes (MWCNTs) to the epoxy resin. The microstructure and performance of the coating were tested by SEM, thermogravimetric analyzer, four-probe conductivity meter, high-temperature friction and wear tester, and electrochemical workstation. The results indicate that the optimal conductivity with a resistivity of 303 Ω ⋅ m is obtained when the MWCNT content is at 4 wt%. In addition, MWCNTs are filled with a network structure of epoxy resin, which increases the density of the coating and enhances their wear and corrosion resistance. [ABSTRACT FROM AUTHOR]

This study considers the regularities in the formation of amorphous–crystalline coatings with zinc oxide and wollastonite particles via micro-arc oxidation (MAO) on metal substrates made from a Mg-0.8 wt.% Ca alloy. The combination of components with increased antibacterial and osteogenic properties made it possible to obtain a unique bioactive and corrosion-resistant coating that slowed down the bioresorption of a magnesium implant and stimulated the processes of osteointegration. The coating was examined using various methods, including scanning and transmission electron microscopy, X-ray crystallography, scratch testing, energy-dispersive X-ray spectroscopy, and potentiodynamic polarization testing. As a result of plasma-chemical interactions between electrolyte components and the magnesium substrate, a porous amorphous–crystalline coating comprising wollastonite (CaSiO3), zinc oxide (ZnO), forsterite (Mg2SiO4), and periclase (MgO) was formed at varying voltages (350–500 V) during the MAO process. The protective properties of the coating were exceptional, as evidenced by the mass loss values of the coated samples (1.4–2.3%) in 0.9% NaCl solution, which were significantly lower than the mass loss of the uncoated alloy (8.9%). The coating synthesized at a voltage of 500 V was characterized by a maximum zinc content of 8 at.%, which was responsible for the highest antibacterial activity against Staphylococcus aureus (99.1%). [ABSTRACT FROM AUTHOR]

Niobium (Nb) and zirconium dioxide (ZrO2) were doped into hydroxyapatite (HA) to fabricate HA-based composite coatings prepared on a ZK60 magnesium alloy by plasma spraying technology to improve anti-corrosion and biocompatibility for clinical applications. The results revealed that the Nb-enriched coating exhibits fewer cracks and pores with a flat surface due to the decreased temperature gradient during spraying, and small needle-like structures can fill the cracks and pores in the ZrO2-contained coating, resulting in a more uniform and dense surface. Compared to coatings with only niobium or zirconium dioxide, the ZrO2/Nb/HA composite coating significantly enhanced the mechanical properties and corrosion resistance of the magnesium alloys. Among all the specimens, the ZrO2/HA coating and ZrO2/Nb/HA coating revealed high surface hardness values (327.73 HV and 293.80 HV, respectively). However, the higher hardness value made the ZrO2/HA coating fragile and more likely to crack, while the ZrO2/Nb/HA coating avoided this shortcoming and exhibited a more comprehensive performance. During immersion tests, the ZrO2/Nb/HA coating exhibited a gradual pH increase and minimal mass loss, and the cytocompatibility test demonstrated promising cellular activity. [ABSTRACT FROM AUTHOR]

Based upon its excellent biocompatibility, manganese (Mn) was used as an alloying element in extruded Mg-2Zn-0.5Gd-1Y Mg alloy for biomedical applications. Besides microstructural evaluation, mechanical and corrosion properties and biocompatibility of the Mg-Zn-Gd-Y-Mn alloys have been investigated by microscopic, tensile and corrosion analyses. Microscopic analysis has revealed the effect of Mn addition prior to extrusion of Mg-2Zn-0.5Gd-1Y grains, which was observed to be refined. Furthermore, the mechanical testing indicated the enhancement of tensile strength up to 265 MPa with 20.5% elongation. The chemical degradation analyses indicated that the Mn addition has effectively reduced the corrosion rate by increasing the corrosion potential of Mg alloys in Hank's solution, which mainly refers to the inhibitory effect of Mn on the reduced precipitation of the Mg-2Zn-0.5Gd-1Y phase. As a result, the formation of Mg (OH)2, calcium and magnesium phosphates with small amounts of Zn, Y and Mg salts, generated after corrosion, form a dense protective layer on the surface of the Mg-alloy, which further protects from surface erosion. The cytotoxicity test has shown that magnesium alloy did not have cell toxicity, showing good cytocompatibility. [ABSTRACT FROM AUTHOR]

In view of the importance of metal coatings, this study addresses the ion concentration of the anti‐corrosive coating's immersion solution. The physical properties of the coating surface, such as molecular characteristics, smoothness, and structural strength, were changed by adding nano‐SiO2 in the immersion solution to formulate the best scheme for anti‐corrosive performance. The composite coating was prepared on the surface of AZ31B magnesium alloy by electroless plating. Besides, the surface coating based on AZ31B substrate has high‐quality corrosion resistance to different types of contaminated media. The experimental results demonstrate that the nanocomposite coating can form an ultrafine particle‐filling effect on the metal surface, which is lower than the drag force of the conventional metal surface. Considering the slip velocity gradient in the contact coating area, we reduce the shear stress and drag force, verifying the nanocomposite coating's effect on reducing the reaction force. The contact angle of water droplets in the composite coating is greater than 158.7°. The study finally verifies that the prepared coating has good self‐cleaning potential which can prevent the corrosion of different polluted media. [ABSTRACT FROM AUTHOR]

Purpose: To improve the corrosion resistance of magnesium alloys, the construction of protective coatings is necessary to extend the service life of Mg-based materials. Design/methodology/approach: SiO2 nanoparticles modified by dodecyltrimethoxysilane (DTMS) were added to the PP and a superhydrophobic Mg(OH)2/PP-60mSiO2 composite coating was fabricated on the surface of AZ31 magnesium alloy via the hydrothermal method and subsequently the immersion treatment. Findings: Hydrophilic SiO2 nanoparticles become hydrophobic after modified by DTMS, showing a higher dispersibility in xylene. By incorporating modified SiO2 nanoparticles into the composite PP coating, the hydrophobicity of the layer was enhanced, resulting in a contact angle of 166.3° and a sliding angle of 3.4°. It also improved the water repellency and durability of the coating. Furthermore, the intermediate layer of Mg(OH)2 significantly strengthened the bond between the PP layer and the substrate. The Mg(OH)2/PP-60mSiO2 composite coating significantly enhances the corrosion resistance of the magnesium alloy by effectively blocking the infiltration of the corrosion anions during corrosion. The corrosion current density of the Mg(OH)2/PP-60mSiO2 composite coating is approximately 8.23 × 10–9 A·cm-2, which can achieve a magnitude three times lower than its substrate, making it a promising surface modification for the Mg alloy. Originality/value: The composite coating effectively and durably enhances the corrosion resistance of magnesium alloys. [ABSTRACT FROM AUTHOR]

To improve the corrosion resistance and antibacterial adhesion properties of AZ31 magnesium alloy as an orthopedic implant material, superhydrophobic hydroxyapatite/lauric acid composite coatings (HA/LA) were successfully fabricated on AZ31 magnesium alloy utilizing the hydrothermal method and followed by immersion treatment in lauric acid solution. The underlying HA coating synthesized by hydrothermal technique presents a micro-/nanohierarchical structure, appearing superhydrophilic, while the composite coatings (HA/LA) obtained by subsequent treatment with lauric acid exhibited excellent superhydrophobic properties with a contact angle of 152.5 ± 1.2° and a rolling angle of 1.5 ± 0.3°. Electrochemical measurements and long-term corrosion resistance test conducted in simulated body fluid (SBF) indicate a significant enhancement in the corrosion resistance of the HA/LA composite coating. Meanwhile, in vitro bacterial experiments demonstrated that the superhydrophobic composite coating surface was able to reduce the adhesion of adherent Escherichia coli and Staphylococcus aureus by more than 98%, showing excellent antibacterial adhesion properties, indicating that the superhydrophobic HA/LA composite coating in this work grants magnesium alloy with excellent corrosion resistance and antibacterial properties. [ABSTRACT FROM AUTHOR]

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present work, the corrosion properties and the surface chemistry of a graphene oxide-coated AZ91D alloy were investigated. The coatings were deposited on the substrate specimens by immersion in solutions with GO concentrations of 0.05% and 0.1% (m/v). An intermediate silane layer was firstly obtained to improve adhesion between the GO films and the AZ91D substrate. The electrochemical behavior of the coated specimens was assessed using electrochemical impedance spectroscopy and potentiodynamic polarization curves in 3.5 wt.% NaCl solution. The surface chemistry was assessed using X-ray photoelectron spectroscopy (XPS). The GO films consisted of a mixture of carbon-based bonds (C-C, C-OH, C=O, and O-C=O). The surface morphology of the coated specimens was examined using scanning electron microscopy. The results revealed that the compactness of the GO films was dependent on the deposition conditions. The corrosion resistance was affected by the surface morphology. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) and Magnesium-Zinc-Calcium alloys present a compelling option for biodegradable implant materials. Utilizing Vacuum Induction Casting, Mg–2.5Zn-xCa (with x = 0.3, 0.5, 0.9, 1.15 wt%) alloys were fabricated and subjected to hot-rolling for thermo-mechanical processing. The hot-rolled Mg–2.5Zn-0.3Ca alloy exhibits the lowest corrosion rate along with the highest basal texture. Increasing the Zn/Ca atomic ratio intensifies the basal texture and enhances corrosion resistance. Elevated Zn concentration improves corrosion resistance via Ca2Mg6Zn3 phase formation, while increased Ca content diminishes corrosion resistance due to the Mg2Ca phase. Advancement of this alloy is poised to extend Mg alloy use in innovative biomedical bone implants. [ABSTRACT FROM AUTHOR]

It is well known that the poor corrosion resistance of magnesium alloys is a key factor limiting their application. Field exposure is the most reliable means to evaluate the atmospheric corrosion performance of magnesium alloys. This article reviews the field exposure corrosion behavior of magnesium alloys in typical atmospheric environments (including the marine atmosphere, industrial atmosphere, etc.) in recent years. According to the literature review, it was found that there are significant regional differences in the atmospheric corrosion behavior of magnesium alloys, which is the result of the coupling of multiple factors in the atmospheric environment. By investigating the corrosion rate and corrosion products of different types of magnesium alloys in different environments, the corrosion mechanism of magnesium alloys in different environments was summarized. Specifically, environmental parameters such as atmospheric temperature, relative humidity, CO2, and chloride ion deposition rates in the marine atmospheric environment can affect the corrosion behavior of magnesium alloys. The corrosion of magnesium alloys in different industrial atmospheric environments is mainly affected by atmospheric temperature and relative humidity, as well as atmospheric pollutants (such as SO2, CO2, NO2) and dust. This review provides assistance to the development of new corrosion-resistant magnesium alloys. [ABSTRACT FROM AUTHOR]

In the present work, a La-based sealing procedure was developed for the anodized AZ31B magnesium alloy. The effects of sealing time and temperature on the electrochemical behavior of the samples were investigated. The corrosion resistance was evaluated in 3.5 wt.% NaCl solution using potentiodynamic polarization tests. Scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) were used to examine the morphology and composition of the sealing films. The results were discussed based on the interplay between film composition, morphological aspects and surface roughness. The best corrosion resistance was obtained for the sample sealed for 20 minutes at 50 °C that exhibited the widest passive range, surpassing that of the anodized (unsealed) sample by more than three times. As indicated by the SEM and XPS results, the formation of a uniform sealed layer comprised of a mixture of La2O3 and La(OH)3 enhanced the corrosion resistance of the anodized AZ31B. [ABSTRACT FROM AUTHOR]

Recently, superhydrophobic magnesium (Mg) alloys are extensively investigated due to their promising applications in corrosion protection and resistance to bacterial adhesion. However, superhydrophobic surfaces may not be conducive to the osteogenic effect of the coated Mg alloys, which limits their clinical application as implants. Herein, the lauric acid (LA)/MoS 2 /Hydroxyapatite (HA) (LMH) superhydrophobic composite coatings were synthesized on AZ31B Mg alloy by hydrothermal process and hydrophobic treatment. The coated Mg alloy had favorable superhydrophobicity, as evidenced by a contact angle measurement of approximately 151.8°. After 3 min of ultrasonic treatment, the contact angle of the coated Mg alloy decreased from 151.8° to 63.5°, which was attribute to the sonothermal effect that changes the surface energy of the coating, hereby removing the air layer at the superhydrophobic interface. Compared to the bare Mg alloy, the electrochemical impedance of the LMH-2.0 superhydrophobic composite coating increased by two orders of magnitude to 89.611 ± 0.593 kΩ cm2. In vitro antibacterial tests showed that the antibacterial efficiency of LMH-2.0 superhydrophobic coating against both S. aureus and E. coli is more than 99% with the assistance of ultrasonic. Meanwhile, the cell fluorescence staining experiments exhibited that the superhydrophobic coating featuring convertible wettability exhibited promising early cell growth and adhesion. The superhydrophobic coatings with wettability transition on magnesium alloys are expected to be ideal modification coatings for degradable implant materials. [ABSTRACT FROM AUTHOR]

This research investigates the interpretation of corrosion patterns using unsupervised machine learning techniques. The use of machine learning techniques using unsupervised approaches has emerged as an important tool in analyzing corrosion data. Mitigating corrosion requires a comprehensive understanding of the intricate patterns and underlying factors governing its occurrence. The workflow consists of analysis of data preparation and evaluation of the model building. The experiments are conducted in the laboratory, and the data collected are then transferred to Google Colaboratory for analysis. Based on the conceptual framework, the data were collected using experimental studies, and a comprehensive corrosion dataset of 127 data points was obtained. We used the choice of clustering algorithms that significantly influenced the outcome of our analysis to identify corrosion patterns within the data. The clustering algorithms used in this article include K-means, affinity propagation, and hierarchical clustering. The choice of these algorithms stems from the quality of the dataset's size distribution and the desired number of clusters. The findings strongly affirm that, in the models examined in this study, K-means clustering stands out as the most effective choice. The proposed system outperforms other methods and can serve as a crucial foundation for comprehending the underlying corrosion behavior. [ABSTRACT FROM AUTHOR]

The paper investigates the effect of silver coating on the corrosion behaviour of magnesium alloy NZ30K alloyed with 0.09 wt.% Ag in Ringer--Locke solution. Samples of the alloy under study are plated with a silver layer of 200-300 nm and 500 nm thickness using the DC-magnetron sputtering system equipped with a circular silver source and target (of 50 mm in diameter) in a gas discharge. An unbalanced magnetron in a 600 mA DC mode at a voltage of 400 V is used. The silver coating at a constant magnetron power of 240 W and a bias voltage of 100 V is applied. The deposition time of a silver layer of 200-300 nm is of 5 minutes, and for 500 nm, is of 15 minutes. As found, the steady-state value of the corrosion potential Ecor for the samples of the studied alloy clad with a silver layer of 200-300 nm is formed during 2060 s from -1.418 up to -1.4449 V, and with 500 nm layer, during 1880 s from -1.433 up to -1.465 V. As recorded, the steady-state value of Ecor for both samples is established in two stages. As found, the rate of shifting of the potential Ecor for the studied samples in the negative direction at the first stage is of 0.062 and 0.034 mV/sec, respectively. As shown, the rate of shifting of Ecor in the negative direction for the sample with a coating thickness of 200-300 nm at this stage is by 1.82 times higher than for the sample with a coating thickness of 500 nm. This is due to a larger number of linear and point defects over the coating with a thickness of 200-300 nm than with 500 nm and more intense contact corrosion. During the transition from the first stage to the second one of the formation of the stationary value of the potential Ecor, its abrupt fluctuation of up to 5 mV is observed that is associated with the delamination of the coating from the alloy in the vicinity of corrosion pits on the surface of the samples due to the contact and crevice corrosions and the mechanical effect of hydrogen bubbles released at the cathodic areas (of silver coating). As shown, the steady-state value of the potential Ecor for the samples of the alloy under study with a coating thickness of 200-300 nm and 500 nm is more positive by 9 and 7%, respectively, than that of the sample of the same alloy without a silver layer. This proves that, by applying silver coatings with different thicknesses, it is possible to control the rate of corrosion dissolution of NZ30K alloy with Ag (0.09 wt.%) in Ringer--Locke solution, and this approach can be used for the fabrication of biodegradable implants for the treatment of broken human bones. [ABSTRACT FROM AUTHOR]

Multifunctional composite coatings have been extensively used to protect metal substrates from corrosion. However, the use of ionic liquids (ILs) to modify the micro-arc oxidation/layered double hydroxides (MAO/LDHs) composite coating, to our best knowledge, has not been reported for the corrosion protection on metal substrates. It is thus necessary to prepare the ILs-modified MAO/LDHs composite coatings and understand in depth their corrosion resistance and active anticorrosive mechanism. Herein, a composite coating is constructed by introducing the MgAl-LDH modified by a choline 3-morpholinopropanesulfonate [Ch][MOPS] ionic liquid on an MAO film (CM-LDH/MAO). It is found that the CM-LDH/MAO composite coating shows the optimal corrosion protection on magnesium alloy, with a corrosion current density of 8.38 × 10−10 A cm−2, clearly lower than those of the MAO and LDH/MAO coatings. More importantly, a small pitting appears at the edge of the CM-LDH/MAO film only after long-term exposure of 216 h in 3.5 wt% NaCl solution. Such an improvement of corrosion resistance can be ascribed to the synergetic mechanism including the physical barrier of the composite coating, the self-repairing ability of the LDH nanosheets on the microporous flaws of the MAO film, as well as the formation effect of the Mg-based chelates by the adsorption of the [Ch]+ cations and the re-adsorption of the [MOPS]– anions released from the LDH interlayers. [ABSTRACT FROM AUTHOR]

To enhance the corrosion resistance of magnesium alloys, an anti-corrosion composite film was prepared by combining anodic oxidation and sol-gel technology. Experimental results indicate that after anodization at 17.5V for 3 min, the composite film obtained through sealing with an MPTMS-modified sol exhibited significant improvements in physical properties. The thickness of the film reached 24.3 μm, its hardness was measured at 164.7 HV, and it demonstrated good surface uniformity. Electrochemical impedance spectroscopy revealed that the impedance modulus at low frequency (|Z| at 0.01 Hz) increased by nearly two orders of magnitude. Furthermore, this study thoroughly explores the corrosion protection mechanism of the composite film, highlighting the role of the sol-gel layer in occupying micro-pores and micro-cracks to form a denser and more uniform protective layer. The dual-layer protection provided by the combination of anodic oxidation and sol-gel layers significantly enhances the overall corrosion resistance of the magnesium alloy. [ABSTRACT FROM AUTHOR]

This study investigates the effect of tin (Sn) addition on the corrosion behavior of hydroxyapatite (HAP) coated Magnesium (Mg)/MgSn alloys by using two different coating methods. Mg/Mg alloys have gained significant attention in recent years due to their lightweight, high strength, and potential for use in a wide range of industrial applications. However, their corrosion properties during cathodic reactions with abundant hydrogen evolution have limited their widespread use, particularly in biomedical appli-cations. In this study, pure Mg, Mg2Sn, Mg3Sn, Mg4Sn, and Mg5Sn alloys were prepared by powder metallurgy method. Then samples were coated by two different methods, dip-coating and electro-deposition. Potentiodynamic polarization and hydrogen evolution reaction analysis were performed to evaluate the corrosion rate and the hydrogen volume released from the alloys. The results indicate that the addition of Sn does not significantly increase the corrosion resistance of MgSn alloys. However, the current density and hydrogen evolution of the alloys are apparently improved after the coating process. The better corrosion resistance was observed for the Mg with higher composition, which are Mg4Sn and Mg5Sn. Overall, the study demonstrates that coating HAP onto the surface of MgSn alloys is able to improve their corrosion behavior and suppress the hydrogen evolution rate (HER) of the MgSn alloys. This improvement in other ways will increase their potential for industrial applications specifically in biomedical applications. [ABSTRACT FROM AUTHOR]

The major drawback of some magnesium alloys is their low corrosion resistance. Therefore, the evaluation of corrosion resistance is a critical factor in developing new alloys and surface treatments. The techniques employed for the determination of corrosion rate include mass loss assessment, hydrogen evolution, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). However, there are still difficulties in precisely estimating this parameter in Mg alloys. In this review, the reported applications, advantages, and disadvantages of the techniques mentioned above were analyzed. On the other hand, a large number of corrosion rate values reported for various Mg alloys in 3 different media (NaCl, Hanks´ solution and SBF), using mass loss, hydrogen evolution, and PP, were compared and analyzed. Generally, corrosion rates obtained from mass loss are higher than those obtained from hydrogen evolution. On the other hand, it is not possible to obtain correlations between corrosion rates obtained from PP and those obtained from mass loss and hydrogen evolution. Even more, dissimilar corrosion rate values are reported for the same alloy, implying that the measuring procedures are not well standardized. [ABSTRACT FROM AUTHOR]

• The carboxylate effect on the degradation of two Mg alloys is studied. • The corrosion behavior of the Mg alloy in a saline with inhibitors is revealed. • The morphology and chemical composition of the protective surface film is analyzed. • The compatibility of the inhibitors with the Ca/P PEO-coating matrix is assessed. • The mechanism of a surface film formation is proposed. The efficiency of the green inhibitors (sodium salts of fumarate, glycolate and gluconate) in suppressing corrosion of the structural MA8 magnesium alloy (Mg Mn Ce) and the biomedical Mg 0.8Ca alloy was studied using the hydrogen evolution measurements, mass loss test, EIS, PDP, SVET/SIET. The analysis of the morphology, chemical composition, and growth kinetic of corrosion films formed in 0.9 wt% NaCl solution with and without corrosion inhibitors was carried out. The most compact surface film with the smallest thickness was formed in a saline solution with sodium fumarate. The Mg alloy samples exhibited the highest polarization resistance, the lowest localized electrochemical activity, and the lowest corrosion rate in saline with the addition of sodium fumarate and sodium glycolate. The efficiency of the applied inhibitors was up to 81 %. The model of the corrosion mechanism based on the sorption of molecules of organic inhibitors is proposed. The results show the high compatibility of the used inhibitors with the calcium-phosphate PEO-matrix, indicating the possibility of forming a self-healing coating by means of these active substances. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Eurasian Physical Technical Journal is the property of E.A. Buketov Karaganda University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polylactic acid (PLA) was coated on biodegradable Mg–Zn–Mn alloys using a sol–gel coating technique for temporary implant applications. The presence of smooth, dense, crack-free PLA coating was evidenced using Fourier transform infrared spectroscopy (FTIR) and a scanning electronic microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDX) module. The strength of the bond between PLA and the Mg–Zn–Mn alloys was investigated as per ASTM D3359 and found to be 4B. The degradation behavior was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy in a simulated body fluid (SBF) solution. The corrosion rate of the PLA–Mg–Zn–Mn sample was found to be 0.00363 mm/y, which is 73% better than the bare Mg–Zn–Mn sample (0.00493 mm/y). In addition, the results of the cytotoxicity assay indicated the cytocompatibility of the implant material on MG-63 osteoblast-like cells, confirming its safety on the bone cells. The efficacy of the use of PLA coating on the biodegradable Mg–Zn–Mn is due to the synergistic effect of both physical and chemical interactions between the PLA layer and the substrate. [ABSTRACT FROM AUTHOR]

In this study, we aim to enhance the corrosion and wear resistance of AZ31 magnesium alloy using electrophoretic deposition (EPD) technology to apply a hydrophobic polytetrafluoroethylene (PTFE) coating. Polyethyleneimine (PEI) serves as a charged dispersant, facilitating uniform deposition of PTFE particles on the alloy surface. Results demonstrate a significant reduction in corrosion current density (from 67.5 μA/cm2 to 5.2 μA/cm2) and improved wear resistance (wear volume decreased from 0.24167 mm3 to 0.00167 mm3) in a 3.5 wt% NaCl solution compared to uncoated alloy. Moreover, the friction coefficient of the coated sample decreases. These findings underscore the potential of nano-PTFE coatings prepared via EPD in enhancing AZ31 magnesium alloy's corrosion and wear resistance, providing a foundation for future protective coating design and optimization. [ABSTRACT FROM AUTHOR]

Fibre metal laminates (FMLs) are the most interesting composite materials of the past decade. They possess the properties of both polymer composites and metallic alloys. However, there is a problem with corrosion when the outer layers are made of aluminium or magnesium. The electrochemical changes that occur during the corrosion process and the mechanisms associated with the corrosion phenomenon are still being investigated. Recently, self-healing phenomena have emerged as a useful approach to prevent corrosion. However, there is limited research on the combination of FMLs and self-healing layers. Therefore, the main purpose of this article is to evaluate the self-healing ability of a magnesium/PEO layer based on microcapsules in a corrosion environment. It was observed that the corrosion mechanism in magnesium alloys is very complex. However, the use of a barrier layer with PEO treatment and microcapsules yielded positive anti-corrosion results. The FML samples were subjected to a 6-week corrosion test, and the addition of microcapsules to the layers showed positive results. In contrast, the samples without microcapsules exhibited intergranular corrosion. In the future, comprehensive tests using self-healing microcapsules in FMLs could greatly enhance their anti-corrosion properties and improve the integrity of the structure. [ABSTRACT FROM AUTHOR]

Overly fast corrosion degradation of biodegradable magnesium alloys has been a major problem over the last several years. The development of protective coatings by using biocompatible, biodegradable, and non-toxic material such as chitosan ensures a reduction in the rate of corrosion of Mg alloys in simulated body fluids. In this study, chitosan/TiO2 nanocomposite coating was used for the first time to hinder the corrosion rate of Mg19Zn1Ca alloy in Hank's solution. The main goal of this research is to investigate and explain the corrosion degradation mechanism of Mg19Zn1Ca alloy coated by nanocomposite chitosan-based coating. The chemical composition, structural analyses, and corrosion tests were used to evaluate the protective properties of the chitosan/TiO2 coating deposited on the Mg19Zn1Ca substrate. The chitosan/TiO2 coating slows down the corrosion rate of the magnesium alloy by more than threefold (3.6 times). The interaction of TiO2 (NPs) with the hydroxy and amine groups present in the chitosan molecule cause their uniform distribution in the chitosan matrix. The chitosan/TiO2 coating limits the contact of the substrate with Hank's solution. [ABSTRACT FROM AUTHOR]

In this investigation, zinc oxide nanoparticles were synthesised using a straightforward microwaveassisted technique. Results showed that the synthesised nanoparticles were hexagonal wurtzite ZnO-nanoparticles with a crystallite size of 6.76 nm, as determined by physio-chemical methods. It reveals, at varying magnifications, the irregularly aggregated, spherically shaped sponge-like structure. Using Fourier transform infrared spectroscopy, corresponding functional groups on ZnO surfaces have been observed. According to absorption measurements, the direct optical bandgap is around 3.29 eV. The photoluminescence spectra may be used to detect crystal defects in the ZnO lattice by looking for red emission and blue band edge emission. An investigation into the anticorrosion capabilities of zinc oxide nanoparticles was conducted, which revealed that the particles have beneficial characteristics when coated with magnesium (Mg) substrates. These materials are evaluated for corrosive resistance with and without a protective coating. Results show that coating significantly increased the protection rate under different electrolyte conditions. Compared to bare Mg plate, the charge transfer resistance Rct was increased when ZnO nanoparticles were coated. [ABSTRACT FROM AUTHOR]

To enhance the corrosion resistance of magnesium alloy while improving its surface roughness to enhance organic bonding, the single pulse micro-arc oxidation treatment was conducted on magnesium alloy specimens for a duration of 1200 seconds. The treatment employed a mixed electrolyte of Na3PO4/Na2SiO3 with varying proportions, aiming primarily to investigate the treatment mechanism. Voltage–time response curves were recorded throughout the entire process. Characterization of the bioceramic films was achieved through the application of SEM, XRD, and XPS techniques, elucidating phase formation, surface morphologies, elemental distribution, and chemical valence. Subsequently, measurements were taken to assess the porosity of the film layer, alterations in thickness, roughness, and the kinetic potential polarization curves. The experimental findings reveal that P and Si elements influence the performance of AZ91D MAO coating by affecting cascading discharge and channel blockage. When the concentration ratio of PO43−/SiO32− in the mixed electrolyte reached 0.02 mol L−1/0.08 mol L−1, the icorr of MAO coating measured 4.6391 μA cm−2, indicating better corrosion resistance. [ABSTRACT FROM AUTHOR]

The biodegradability and lightweight qualities of magnesium make it an appealing material for usage in aerospace and automotive applications and orthopedics. Magnesium is susceptible to corrosion, which restricts its use. Magnesium should be protected against corrosion in order to be used to its maximal potential. Corrosion inhibitors are one of the most well-liked and affordable techniques to stop corrosion in magnesium and its alloys. Chemicals, which are frequently used as corrosion inhibitors include biotoxic ones, which raise serious toxicity issues. There is a great deal of interest in creating a green corrosion inhibitor, which is non-toxic and safe for the environment due to the toxicity of the current inhibitors. This paper discusses the common green corrosion inhibitors. The application of ecologically friendly corrosion inhibitors for magnesium and its alloy is still being pursued by a relatively small number of scientists. The research utilizing green corrosion inhibitors for magnesium alloy has been reviewed in detail. In addition, the performances are tabulated and analyzed. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to examine the impact of MoS2 on the microstructure and characteristics of micro-arc oxidized (MAO) ceramic coatings created on ZK60 magnesium alloy through the addition of varying concentrations of MoS2 particles to the electrolyte, aiming to enhance the corrosion resistance of magnesium alloy. Design/methodology/approach: The surface morphology, roughness and phase composition of the coatings were analyzed using scanning electron microscopy, a hand-held roughness tester and an X-ray diffractometer, respectively, and the corrosion resistance of the MAO coatings prepared by the addition of different contents of MoS2 particles was tested and analyzed using an electrochemical workstation. Findings: The results demonstrate that MoS2/MgO composite coatings have been successfully prepared on the surface of magnesium alloys through micro-arc oxidation. Furthermore, the corrosion resistance of the ZK60 magnesium alloy prepared with the addition of 1.0 g/L MoS2 was the best compared to the other samples. Originality/value: MoS2 particles were able to penetrate the coatings successfully during the micro-arc oxidation process, acting as a barrier in the micropores to prevent the corrosion medium from touching the surface, thus improving the corrosion resistance of the sample. The electrochemical workstation was used to study the corrosion resistance of the MoS2/MAO coating on the ZK60 magnesium alloy. [ABSTRACT FROM AUTHOR]

• NH 4 + accelerates corrosion of AZ31 alloy in the Cl−-SO 4 2− system. • Buffering ability of NH 4 + is the dominant factor in NH 4 +-induced acceleration of AZ31 alloy. • High coverage of h ads generates an inductive loop within the low frequency range. • NH 4 + causes thinning and perforation of inner MgO layer and poriness of outer Mg(OH) 2. • SO 4 2− helps to generate cracked but partially protective products and Cl− broadens the active corrosion area. Electrochemical corrosion of AZ31 magnesium alloy in the NH 4 +-SO 4 2−-Cl− environment is studied. Effect of NH 4 + overshadows that of Cl− as the (NH 4) 2 SO 4 concentration is 0.005 M or higher, yielding an evolution from localized corrosion to uniform corrosion. Acceleration effect of NH 4 + can be attributed to that (i) NH 4 + dissolves the inner MgO and hinders the precipitation of Mg(OH) 2 and (ii) the buffering ability of NH 4 + provides H+, enhances the hydrogen evolution, and expedites the corrosion process. The latter is demonstrated as the dominant factor with the results in unbuffered and buffered environments. The severe corrosion and hydrogen process in NH 4 +-containing solution results in a high H ads coverage and yields an inductive loop within the low frequency. Meanwhile, SO 4 2− is helpful in generating cracked but partially protective corrosion products, while Cl− could broaden the corrosion area beneath the corrosion product. [ABSTRACT FROM AUTHOR]

Magnesium alloys, notably AZ31B, hold promise for lightweight structural applications in the aerospace, automotive, and biomedical sectors due to their excellent strength-to-weight ratios. The broad adoption of these alloys, however, is hindered by their inherent susceptibility to corrosion, reducing durability and functional integrity in corrosive environments. This study explores anodic oxidation as a viable surface treatment to improve the corrosion resistance of the AZ31B magnesium alloy. Focusing on the impact of oxidation voltage on the oxide film's structural and electrochemical properties, we aim to optimize these characteristics to enhance the alloy's utility and lifespan significantly. Through detailed analysis of surface and cross-sectional morphologies, film thickness, phase composition, and corrosion resistance, we identify an optimal oxidation voltage of 17.5 V that notably improves the oxide film's density and corrosion resistance. Through this research, we contribute to the ongoing efforts to overcome the corrosion vulnerability of magnesium alloys, thereby unlocking their full potential in contributing to more sustainable and efficient technological advancements. [ABSTRACT FROM AUTHOR]

A self-sealing coating was prepared on the surface of basic magnesium alloy material (BM) by micro-arc oxidation (MAO) technique. The corrosion behavior of BM and MAO samples in a simulated body fluid (SBF) at different flow rates (0, 0.5, and 1.5 ml/s) was studied by immersion test. The electrochemical impedance spectrum (EIS) of the samples was measured at 0, 2, 12, 16 and 24 h during the immersion process to analyze the evolution of the electrochemical corrosion resistance. The corrosion morphology and element composition of the samples were characterized by scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The results showed that the corrosion resistance of BM and MAO samples gradually decreases with increasing flow rate. At higher flow rates, the MAO coating is more effective in improving the corrosion resistance of magnesium alloys. Based on the experimental results, the corrosion mechanism of BM and MAO samples at different flow rates was clarified. [ABSTRACT FROM AUTHOR]

The aim of the present work was to study the effect of graphene oxide as an additive in the anodization bath of the ZK60A magnesium alloy on the corrosion resistance, film morphology and surface chemical composition. The anodizing process was conducted at a constant current density of 30 mA.cm−2 in an electrolyte consisting of 3 M de KOH, 0.15 M de Na2SiO3 and 0.1 M Na2B4O7.10H2O. Graphene oxide was added to this bath at three different concentrations: 0.5 g.L−1, 1.0 g.L−1 and 3.0 g.L−1. The ability of the graphene oxide nanofiller to enhance the corrosion resistance of the ZK60A alloy was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization tests in 3.5 wt.% NaCl solution. The surface chemical composition was assessed by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) coupled with EDS analysis was employed to examine the anodized layer morphology and thickness. The results pointed to a beneficial effect of graphene oxide addition on the corrosion resistance of the anodized ZK60A which was dependent on the concentration of the nanofiller in the anodizing electrolyte. [ABSTRACT FROM AUTHOR]

The corrosion of magnesium alloys is often considered to differ in behaviour and development with time from most other metals and alloys because they show evolution of hydrogen right from first exposure. However, data extracted from the open literature indicate that magnesium alloys develop corrosion mass-loss trends with time that are consistent with the so-called bimodal pattern, which is topologically similar to those of other alloys. Examples are given of such trending for magnesium alloys under immersion, half-tide and various atmospheric exposure conditions. The critical roles of corrosion pitting and its development into localised corrosion are discussed. For high-purity magnesium alloys, the transition to longer-term corrosion, which is rate-controlled by the hydrogen evolution cathodic reaction, occurs quickly, within days. Comments are made about the application of measurements of hydrogen evolution and of electrochemical methods to make rapid estimates of shorter-term corrosion rates. [ABSTRACT FROM AUTHOR]

The poor corrosion resistance of magnesium alloy is a crucial obstacle to its further extensive application. The superhydrophobic surfaces can enhance the anti-corrosion performance of many materials. In this work, a superhydrophobic calcium myristate coating with a peony flower-like structure was successfully fabricated on the AZ91D alloy surface by electrodeposition to enhance corrosion resistivity. The mechanisms of the coating formation and corrosion resistance, and the effects of electrodeposition voltages on the microstructure and wettability were discussed. The results showed that the superhydrophobic coating with a WCA of 154° ± 0.8° possessed excellent self-cleaning property. Moreover, by comparison with the AZ91D substrate, the corrosion current density of the superhydrophobic coating dramatically decreased. The superhydrophobic coating has shown an excellent corrosion resistance after exposure for 72 h. It is expected that the superhydrophobic coating has a broad application prospect in corrosion resistance. [ABSTRACT FROM AUTHOR]

Magnesium alloy stents have been extensively studied in the field of biodegradable metal stents due to their exceptional biocompatibility, biodegradability and excellent biomechanical properties. Nevertheless, the specific in vivo service environment causes magnesium alloy stents to degrade rapidly and fail to provide sufficient support for a certain time. Compared to previous reviews, this paper focuses on presenting an overview of the development history, the key issues, mechanistic analysis, traditional protection strategies and new directions and protection strategies for magnesium alloy stents. Alloying, optimizing stent design and preparing coatings have improved the corrosion resistance of magnesium alloy stents. Based on the corrosion mechanism of magnesium alloy stents, as well as their deformation during use and environmental characteristics, we present some novel strategies aimed at reducing the degradation rate of magnesium alloys and enhancing the comprehensive performance of magnesium alloy stents. These strategies include adapting coatings for the deformation of the stents, preparing rapid endothelialization coatings to enhance the service environment of the stents, and constructing coatings with self-healing functions. It is hoped that this review can help readers understand the development of magnesium alloy cardiovascular stents and solve the problems related to magnesium alloy stents in clinical applications at the early implantation stage. [ABSTRACT FROM AUTHOR]

Purpose: The high specific strength makes magnesium alloys have a wide range of applications in aerospace, military, automotive, marine and construction industries. However, its poor corrosion resistance and weldability have limited its development and application. Friction stir welding (FSW) can effectively avoid the defects of fusion welding. However, the microstructure, mechanical properties and corrosion behavior of FSW joints in magnesium alloys vary among different regions. The purpose of this paper is to review the corrosion of magnesium alloy FSW joints, and to summarize the protection technology of welded joints. Design/methodology/approach: The corrosion of magnesium alloy FSW joints includes electrochemical corrosion and stress corrosion. This paper summarizes corrosion protection techniques for magnesium alloys FSW joints, focusing on composition, microstructure changes and surface treatment methods. Findings: Currently, this research is mainly focused on enhancing the corrosion resistance of magnesium alloy FSW joints by changing compositions, structural modifications and surface coating technologies. Refinement of the grains can be achieved by adjusting welding process parameters, which in turn minimizes the effects of the second phase on the alloy's corrosion resistance. Originality/value: This paper presents a comprehensive review on the corrosion and protection of magnesium alloys FSW joints, covering the latest research advancements and practical applications. It aims to equip researchers with a better insight into the field and inspire new studies on this topic. [ABSTRACT FROM AUTHOR]

The high corrosion susceptibility of magnesium alloy has become a practical problem which restricts its wide application in many fields. To improve its surface properties, a composite coating has been successfully prepared on the surface of AZ91D magnesium alloy using a one‐step hydrothermal method. The coating surface possesses a dense structure in the form of scales and has an adhesion strength of 3B. The effect of different preparation conditions on the coating thickness and corrosion resistance is discussed. The coating heated at 180°C for 2 h showed the best corrosion resistance in a 3.5 wt% sodium chloride solution, with a reduction in corrosion current density of 5 orders of magnitude compared to the bare sample. This solution significantly improved the corrosion resistance of the magnesium alloy and helped to further realize the application of magnesium alloys in corrosive environments. [ABSTRACT FROM AUTHOR]

The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-xZn-0.5Zr (x = 0, 2, 4, 6 wt.%) alloys were investigated by optical microscopy, scanning electron microscopy, energy-dispersive spectrometry and X-ray Diffraction. The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment. The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-xZn-0.5Zr (x = 0, 2, 4, 6 wt.%) alloys were analyzed by weight loss rate, corrosion depth, corrosion products and corrosion morphologies. The electrochemical corrosion tests were also measured in the natural seawater. The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment. That depended on the microstructure, type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy. Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance. [ABSTRACT FROM AUTHOR]

HA-rGO-ZnO ternary composite coatings were successfully prepared on ZK60 magnesium alloy using cathodic electrophoretic deposition method. XRD analysis proved the addition of ZnO nanoparticles induced a significantly reduced crystallinity in hydroxyapatite and the tensile strain values of HA-rGO-ZnO composite coatings gradually decreased as the content of ZnO increased. SEM analyses revealed that the HA and ZnO nanoparticles were anchored on rGO nanosheets and a closely-packed network of recrystallization needle-like ZnO and mineralization HA crystals was formed on the surface of HA-rGO-ZnO coated sample. The resulting composite coating exhibited a uniform and compact HA-rGO-16ZnO composite coating, with well adhered to the ZK60 magnesium alloy substrate. The HA-rGO-16ZnO coated sample exhibited the highest corrosion resistance with lowest i corr (1.12 × 10−6 A/cm2) and the highest E corr (−1.43 V/SCE) value when compared to HA-rGO-14ZnO and HA-rGO-18ZnO samples after immersion in a SBF for 10 min. Compared to HA-rGO-ZnO coated samples after 10 min of immersion in SBF, HA-rGO-ZnO coated samples after 3 days of immersion in SBF exhibited a remarkably improved corrosion resistance and rapid inducing of the apatite layer precipitated on the surface of the composite coatings. The microstructure and composition for the coated samples after 3 days of immersion in SBF also confirm that the presence of a apatite layer on the composite coatings. HA-rGO-18ZnO coated samples after 3 days of immersion in SBF showed the lowest i corr value, which indicating HA-rGO-18ZnO ternary composite coatings dramatically improved the formation ability of the apatite layer and led to an enhancement in the bioactivity. Accordingly, it is believed that the HA-rGO composite coating incorporated with ZnO will be a potential candidate for bone biomedical applications. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys have the potential for widespread application in aerospace components, communications, biomaterials and electronic industry due to their low density, high thermal conductivity and outstanding mechanical properties (strength and toughness). However, the poor anti-corrosion property of Mg alloys strictly hinders their applications in practice. Laser surface remelting (LSR) is an effective way to improve the corrosion-resistant of Mg alloys, but it is easy to form micropores in the process of laser processing. Therefore, in this work, we combined LSR and layered double hydroxides (LDHs) film to further improve the corrosion resistance of Mg alloys. The results show that the composite films greatly improve the anti-corrosion of Mg alloys, which provide a guidance for the designing of corrosion-resistant coating on Mg alloys. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect in vivo. A bioactive chemical conversion Mg-phenolic networks complex coating (eEGCG) was stepwise incorporated by epigallocatechin-3-gallate (EGCG) and exogenous Mg2+ on Mg-2Zn magnesium alloy. Simplex EGCG induced chemical conversion coating (cEGCG) was set as compare group. The in vitro corrosion behavior of Mg-2Zn alloy, cEGCG and eEGCG was evaluated in SBF using electrochemical (PDP, EIS) and immersion test. The cytocompatibility was investigated with rat bone marrow mesenchymal stem cells (rBMSCs). Furthermore, the in vivo tests using a rabbit model involved micro computed tomography (Micro-CT) analysis, histological observation, and interface analysis. The results showed that the eEGCG is Mg-phenolic multilayer coating incorporated Mg-phenolic networks, which is rougher, more compact and much thicker than cEGCG. The eEGCG highly improved the corrosion resistance of Mg-2Zn alloy, combined with its lower average hemolytic ratios, continuous high scavenging effect ability and relatively moderate contact angle features, resulting in a stable and suitable biological environment, obviously promoted rBMSCs adhesion and proliferation. More importantly, Micro-CT, histological and interface elements distribution evaluations all revealed that the eEGCG effectively inhibited degradation and enhanced bone tissue formation of Mg alloy implants. This study puts forward a promising bioactive chemical conversion coating with Mg-phenolic networks for the application of biodegradable orthopedic implants. [ABSTRACT FROM AUTHOR]

• Corrosion protection for Mg alloys. • Engineering self-repairing coatings is considered as an effective strategy, because they can enable the timely repair for damaged areas, which brings about long-term protection for Mg alloys. • On the basis of the state-of-the art molecular design of building blocks, one is able to synthesize diverse COF frameworks with defined but tailored microstructures, endowing the coating with stimulus response function to achieve better corrosion prevention effect. • As a novel carrier and barrier, porous solids, especially covalent organic frameworks (COFs), have been respected as the future development of self-repairing coatings on Mg alloys, due to their unique, diverse structures and adjustable functions. Featuring low density and high specific strength, magnesium (Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properties make them susceptible to corrosion in humid, seawater, soil, and chemical medium. Various strategies have revealed certain merits of protecting Mg alloys. Therein, engineering self-repairing coatings is considered as an effective strategy, because they can enable the timely repair for damaged areas, which brings about long-term protection for Mg alloys. In this review, self-repairing coatings on Mg alloys are summarized from two aspects, namely shape restoring coatings and function restoring coatings. Shape restoring coatings benefit for swelling, shrinking, or reassociating reversible chemical bonds to return to the original state and morphology when coatings broken; function self-repairing coatings depend on the release of inhibitors to generate new passive layers on the damaged areas. With the advancement of coating research and to fulfill the demanding requirements of applications, it is an inevitable trend to develop coatings that can integrate multiple functions (such as stimulus response, self-repairing, corrosion warning, and so on). As a novel carrier and barrier, porous solids, especially covalent organic frameworks (COFs), have been respected as the future development of self-repairing coatings on Mg alloys, due to their unique, diverse structures and adjustable functions. [ABSTRACT FROM AUTHOR]

An environmentally friendly alkaline electrolyte of silicate and borate, which contained the addition of carbohydrates (lactose, starch, and dextrin), was applied to produce micro-arc oxidation (MAO) coatings on AZ31B magnesium alloy surfaces in constant current mode. The effects of the carbohydrates on the performance of the MAO coatings were investigated using a scanning electron microscope (SEM), an X-ray diffractometer (XRD), energy-dispersive spectroscopy (EDS), the salt spray test, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS). The results show that the carbohydrates effectively inhibited spark discharge, so the anodized growth process, surface morphology, composition, and corrosion resistance of the MAO coatings were strongly dependent on the carbohydrate concentration. This is ascribed to the surface adsorption layer formed on the surface of the magnesium alloy. When the carbohydrate concentration was 10 g/L, smooth, compact, and thick MAO coatings with excellent corrosion resistance on the magnesium alloy were obtained. [ABSTRACT FROM AUTHOR]

While magnesium alloys have garnered attention for their lightweight properties across diverse applications, their susceptibility to corrosion presents a formidable challenge. Recent years have witnessed the emergence of machine learning (ML) as a formidable tool for predicting and augmenting material properties, notably corrosion resistance. This comprehensive review investigates the latest advancements and hurdles in utilizing ML techniques to investigate the corrosion behavior of magnesium alloys. This article delves into a spectrum of ML algorithms, encompassing artificial neural networks, support vector machines, and random forests, elucidating their roles in predicting corrosion rates, morphologies, and other corrosion-related characteristics in magnesium alloys. Furthermore, it underscores the pivotal challenges and opportunities within this field, such as data quality, model interpretability, and model transferability. Finally, it examines the potential of ML methods in the conception and enhancement of magnesium alloys endowed with superior corrosion resistance. This review aspires to offer valuable insights into harnessing ML's potential for optimizing magnesium alloy designs with heightened corrosion resistance, a facet of paramount importance across diverse industries, including the automotive, aerospace, and biomedical sectors. By addressing the challenges inherent in using ML to forecast corrosion rates, including data limitations and the intricacies of corrosion mechanisms, ML stands poised to emerge as a potent instrument for advancing the development of corrosion-resistant materials. [ABSTRACT FROM AUTHOR]