Corrosion Of Magnesium Alloys Research Articles

Effect of Polytetrafluoroethylene Coating on Corrosion Wear Properties of AZ31 Magnesium Alloy by Electrophoretic Deposition

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.

Effect of tissue fixatives on the corrosion of biomedical magnesium alloys

In this work, the corrosion behavior of pure Mg, Mg3Ag, Mg6Ag, and MgZnYNd alloys in different fixatives (ethyl alcohol (EA), 85% ethyl alcohol (85% EA), 10% neutral buffered formalin (10% NBF), 4% glutaric dialdehyde (4% GD), and 4% paraformaldehyde (4% PFA)) was investigated to provide a valuable reference for the selection of fixatives during the histological evaluation of Mg implants. Through the hydrogen evolution test, pH test, and corrosion morphology and product characterization, it was found that corrosion proceeded slowest in the EA and 85% EA groups, slightly faster in 4% GD, faster in 10% NBF, and fastest in 4% PFA. After corrosion, the EA group surface remained unchanged, while the 85%EA group surface developed minor cracks and warping. The 4%GD fixative formed a dense needle-like protective layer on the Mg substrate. The 10%NBF group initially grew a uniform layer, but later developed irregular pits due to accelerated corrosion. In contrast, the 4%PFA solution caused more severe corrosion attributed to chloride ions. The main corrosion products in the EA and 85%EA groups were MgO and Mg(OH)2, while the other fixatives containing diverse ions also yielded phosphates like Mg3(PO4)2 and MgHPO4. In 4% PFA, AgCl formed on the surface of Mg6Ag alloy after corrosion. Therefore, to minimize Mg alloy corrosion without compromising staining quality, EA or 85% EA is recommended, while 4% PFA is not recommended due to its significant impact.

Corrosion resistance of hybrid plasma electrolytic oxidation coatings on AZ31B magnesium alloy in simulated body fluid

This study examines the effects of a hydroxyapatite/anatase TiO2/CeO2 coating on the corrosion of AZ31B magnesium alloy in a simulated body fluid. Plasma electrolytic oxidation (PEO) is used to create the coating, and the surface properties are analysed using X-ray diffraction (XRD), atomic force microscopy (AFM) and field-emission scanning electron microscopy (FE-SEM). Contact angle measurements adapted to compare the uncoated substrate (144.74 ± 2.08°) with the coated substrates, which exhibit contact angles of (107.92 ± 2.16°), (95.88 ± 2.06°) and (66.05 ± 2.09°) for the respective coating durations. Increasing the thickness of the coating improves its corrosion resistance. Specifically, a 6-minute PEO coating significantly increases the thickness and provides better protection against corrosion for the AZ31B magnesium alloy. Cross-sectional scans of the coated samples revealed an increase in specimen thickness from 32.92 μm to77.17 μm. Potentiodynamic polarisation tests in a simulated body fluid reveal that the 6-minute coated sample shows the highest corrosion resistance, with the lowest corrosion current density (1.9037 × 10-06) compared to other coatings, indicating strong protection against corrosion. This research proposes a novel method to enhance the corrosion resistance of PEO coatings on magnesium alloys by depositing a thicker layer of hydroxyapatite, anatase TiO2 and CeO2. This approach results in a stronger and more effective protective system against corrosion.

Effect of indium and yttrium on the corrosion behavior of AZ63 magnesium alloy

Indium (In) and yttrium (Y) can activate and alleviate the corrosion of magnesium alloy, respectively. The effects of 1 wt% In and 1 wt% Y on the microstructure and electrochemical behaviors of Mg-6 wt%Al-3 wt%Zn (AZ63) magnesium alloy are investigated via materials characterizations associated with electrochemical techniques. The results showed that co-alloying of In and Y would increase the number of intermetallic phases in AZ63 by generating discrete Al2Y phase and continuous Mg17Al12 phase. During the process of corrosion, the corrosion of Mg-6 wt%Al-3 wt%Zn-1 wt%In-1 wt%Y(AZ63InY) initiates from the intermetallic phases and propagates locally. The corrosion products are apt to adhere on the corroded surface, underneath which a severe corrosion takes place due to the enhanced dissolution-reprecipitation effect of In on activating Mg.

Evaluation of Corrosion Performance of AZ31 Mg Alloy in Physiological and Highly Corrosive Solutions.

Resorbable Mg and Mg alloys have gained significant interest as promising biomedical materials. However, corrosion of these alloys can lead to premature reduction in their mechanical properties, and therefore their corrosion rate needs to be controlled. The aim of this study is to select an appropriate environment where the effects of coatings on the corrosion rate of the underlying Mg alloy can be discerned and measured in a relatively short time period. The corrosion resistance of uncoated AZ31 alloy in different solutions [Hank's Balanced Salt Solution, 1× phosphate buffered solution (PBS), 4× PBS, 0.9%, 3.5%, and 5 M sodium chloride (NaCl)] was determined by measuring the weight loss over a 2 week period. Upon exposure to physiological solutions, the uncoated AZ31 alloys exhibited a variable weight increase of 0.4 ± 0.4%. 3.5% and 5 M NaCl solutions led to 0.27 and 9.7 mm/year corrosion rates, respectively, where the compositions of corrosion products from AZ31 in all saline solutions were similar. However, the corrosion of the AZ31 alloy when coated by electrochemical oxidation with two phosphate coatings, one containing fluorine (PF) and another containing both fluorine and silica (PFS), showed 0.3 and 0.25 mm/year corrosion rates, respectively. This is more than 30 times lower than that of the uncoated alloy (7.8 mm/year), making them promising candidates for corrosion protection in severe corrosive environments. Cross-sections of the samples showed that the coatings protected the alloy from corrosion by preventing access of saline to the alloy surface, and this was further reinforced by corrosion products from both the alloy and the coatings forming an additional barrier. The information in this paper provides a methodology for evaluating the effects of coatings on the rate of corrosion of magnesium alloys.

A Cu(Ⅱ)-eluting coating through silk fibroin film on ZE21B alloy designed for in situ endotheliazation biofunction

In the cardiovascular field, coating containing copper used to catalyze NO (nitric oxide) production on non-degradable metal surfaces have shown unparalleled expected performance, but there are few studies on biodegradable metal surfaces. Magnesium-based biodegradable metals have been applied in cardiovascular field in large-scale because of their excellent properties. In this study, the coating of copper loaded in silk fibroin is fabricated on biodegradable ZE21B alloy. Importantly, the different content of copper is set to investigate the effects of on the degradation performance and cell behavior of magnesium alloy. Through electrochemical and immersion experiments, it is found that high content of copper will accelerate the corrosion of magnesium alloy. The reason is the spontaneous micro-batteries between copper and magnesium with the different standard electrode potentials, that is, the galvanic corrosion accelerates the corrosion of magnesium alloy. Moreover, the coating formed through silk fibroin by the right amount copper not only have a protective effect on the ZE21B alloy substrate, but also promotes the adhesion and proliferation of endothelial cells in blood vessel micro-environment. The production of NO catalyzed by copper ions makes this trend more significant, and inhibits the excessive proliferation of smooth muscle cells. These findings can provide guidance for the amount of copper in the coating on the surface of biodegradable magnesium alloy used for cardiovascular stent purpose.

Trends in Longer-Term Corrosion Loss of Magnesium Alloys

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.

Mechanical, electrochemical corrosion, and high-temperature oxidation properties of stir-cast and heat-treated AZ80 magnesium alloy

This study aims to produce a stir-cast AZ80 magnesium alloy and to correlate the phases and microstructure of the as-cast, T4, and T6 conditions with the alloy's mechanical, corrosion, and oxidation properties. Microstructure was analysed using Field Emission Scanning Electron Microscopy (FE-SEM) with Energy Dispersive Spectroscopy (EDS), Electron Backscatter Diffraction (EBSD), and High-Resolution Transmission Electron Microscopy (HRTEM), and X-ray diffraction (XRD) technique was employed to examine at the alloy’s phases. A Vickers microhardness, tensile, and impact test specimens were meticulously prepared according to ASTM specifications. The electrochemical corrosion was tested in 0.6 M NaCl and 0.05 H2SO4, simulating the salty seawater and low-sulphur air environments. Based on the eutectic temperature of the Mg-Al alloy system, which is 437 ℃, the high-temperature oxidation test was carried out at 400 ℃, 410 ℃, and 420 ℃. Microstructural study confirms that both T4 and T6 alloys undergo grain coarsening with a grain size of 72.64 µm, and the orientation of the grains shifted from the pyramidal plane (2−1-10) to the basal plane (0001). The TEM investigation helps pinpoint the GP zone's genesis in T4 heat-treated AZ80. T4 AZ80 has a maximum ultimate tensile strength of 306 MPa and a ductility of 29.77% because of the dispersion-strengthening effect. The T6 AZ80, on the other hand, has a minimum corrosion rate of 0.158 mm/year in NaCl solution and an oxidation rate constant of 4.19 mg2.cm−4h−1 at 420 ⁰C. Notably, the T6 AZ80 shows significant peaks of Mg2Al3, and the as-cast shows more peaks of Mg17Al12. Magnesium alloy AZ80 is significantly affected by intermetallic phases like Mg17Al12 and Mg2Al3. The Mg2Al3 phase shows the latter tendency to resist corrosion and oxidation.

Corrosion and adhesion properties of MAO-coated LA91 magnesium alloy

Magnesium–lithium alloy is used in different areas of industry and is known as a super light metallic engineering material. However, the use of these alloys is limited due to their surface properties under extreme loads and aggressive environments. Surface treatments can be applied to these alloys to increase their usage areas and improve their weak surface properties. In this study, the micro-arc oxidation method was applied to improve the surface properties of LA91 alloy. The corrosion and adhesion behaviour of the coated samples were investigated. The lowest corrosion current density in the coatings was obtained under Experiment 3. Experiment 3 has the highest Lc2 value due to the coating thickness and the denser and smaller diameter pores of the functional intermediate layer.

Contribution of Oxygen Reduction to Mg Corrosion: Experimental Evidence By Electrochemical Microprobes

Unravelling the mechanisms of magnesium corrosion is vital for establishing reliable research methodologies, developing new alloys and predicting magnesium degradation behaviour. Hydrogen evolution reaction is widely regarded as by far the main cathodic process during corrosion of magnesium. Hence, tracing the amount of released hydrogen was thought to be a reliable measure of magnesium degradation rate. Recently, experimental evidences obtained by different methods have been presented by several groups that oxygen reduction (ORR) is important secondary cathodic reaction during Mg corrosion [1-8]. For model galvanic couple Al-Cu-Mg, oxygen consumption on the surface of Mg along with that on Cu was observed by using oxygen sensing microoptode [1]. A simultaneous measurement of local current density by scanning vibrating electrode technique (SVET) and local oxygen concentration by oxygen sensing microoptode found a strong oxygen consumption at the active corrosion sites on the surface of commercially pure Mg in NaCl electrolyte [2]. Then, the evidence for the varying contributions of ORR to the total cathodic process on Mg alloys during atmospheric and aqueous corrosion was presented based on newly developed respirometric methods [3-5]. While around 10% of the total cathodic current was ascribed to ORR during aqueous corrosion, up to 60% of the total corrosion process was shown to be due to the ORR contribution during simulated atmospheric corrosion with wet-dry cycles. Nanoparticle-based O2 imaging was used to map decreased O2 concentration at the interface of several Mg alloys exposed to simulated body fluids [6].High ORR rate on a slowly corroding ultra-high-purity Mg (UHP-Mg) in NaCl electrolyte was shown in our recent work [7]. Comparing that with lower ORR rate for faster corroding commercial purity Mg (CP-Mg), the rate of ORR was found to depend on the growth rate of Mg(OH)2 , which is the main corrosion product of Mg in the simple saline solution. The formation of Mg(OH)2 impeded the diffusion of oxygen from bulk electrolyte to metal interface, preventing metallic Mg substrate from the interaction with oxygen. The distribution of local concentration of dissolved gaseous H2 and O2 assessed by amperometric Clark-type micorprobes at the interface of UHP-Mg and CP-Mg demonstrated the inverse relationship between HER and ORR, and supports the finding that diffusion-controlled ORR highly depends on the barrier property of corrosion products on the surface [8]. The contribution of ORR current to total cathodic current reached 29.1% for UHP-Mg, while only 0.9% for CP-Mg after 1 hour of immersion in NaCl solution. The contribution of ORR decreases with immersion time, due to the impeded access of dissolved O2 to Mg interface caused by thickening of Mg(OH)2 layer. A numerical model was developed considering the mixed potential diagram and measured local oxygen concentration. REFERENCES: [1] D. Snihirova, M. Taryba, S.V. Lamaka, M.F. Montemor, Corrosion inhibition synergies on a model Al-Cu-Mg sample studied by localized scanning electrochemical techniques, Corrosion Science, 112 (2016) 408-417.[2] E.L. Silva, S.V. Lamaka, D. Mei, M.L. Zheludkevich, The Reduction of Dissolved Oxygen During Magnesium Corrosion, ChemistryOpen, 7 (2018) 664-668.[3] M. Strebl, S. Virtanen, Real-Time Monitoring of Atmospheric Magnesium Alloy Corrosion, Journal of The Electrochemical Society, 166 (2019) C3001-C3009.[4] M. Strebl, M. Bruns, S. Virtanen, Editors’ Choice—Respirometric in Situ Methods for Real-Time Monitoring of Corrosion Rates: Part I. Atmospheric Corrosion, Journal of The Electrochemical Society, 167 (2020) 021510.[5] M. Strebl, M.P. Bruns, G. Schulze, S. Virtanen, Respirometric In Situ Methods for Real-Time Monitoring of Corrosion Rates: Part II. Immersion, Journal of the Electrochemical Society, (2021).[6] B. Zeller-Plumhoff, A.R. Akkineni, H. Helmholz, D. Orlov, M. Mosshammer, M. Kühl, R. Willumeit-Römer, M. Gelinsky, Oxygen-sensitive nanoparticles reveal the spatiotemporal dynamics of oxygen reduction during magnesium implant biodegradation, NPJ Materials Degradation, 6 (2022) 95.[7] C. Wang, D. Mei, G. Wiese, L.Q. Wang, M. Deng, S.V. Lamaka, M.L. Zheludkevich, High rate oxygen reduction reaction during corrosion of ultra-high-purity magnesium, NPJ Materials Degradation, 4 (2020) 42.[8] C. Wang, W. Xu, D. Höche, M.L. Zheludkevich, S.V. Lamaka, Exploring the contribution of oxygen reduction reaction to Mg corrosion by modeling assisted local analysis, Journal of Magnesium and Alloys, 11 (2023) 100-109. ACKNOWLEDGEMENTS: C. Wang, Wen Xu, thank China Scholarship Council for the funding, grants no. 201806310128 and 201908510177

Development of Ti/Ti-DLC multilayers on magnesium alloys — Part 2: Corrosion and wear resistance

To improve corrosion and wear resistance of magnesium alloy, the Ti-DLC monolayer and Ti/Ti-DLC multilayer films were deposited on AZ31 magnesium alloys by filter cathodic vacuum arc deposition technology. All coatings showed good corrosion and wear resistance, and low friction coefficient. The corrosion resistance of the coated samples, from high to low, was Ti/Ti-DLC)2 multi coated-, Ti-DLC mono coated-, and Ti/Ti-DLC)4 multi coated samples. That is because the good toughness and film/substrate deformation coordination of multilayer films were beneficial for improving the corrosion resistance of coating, but the thinner Ti sublayer increased the risk of corrosion liquid penetrating the coating. Under friction test under 5 N load for 30 min, the Ti-DLC monolayer film showed best wear resistance with lowest wear rate as its combination effects of high hardness and good toughness. Whereas, under higher load, the higher toughness and film/substrate deformation coordination of multilayer films played a more positive role in its wear life. Under load of 10 N, comparing to the Ti-DLC monolayer film, the (Ti/Ti-DLC)4 multi and (Ti/Ti-DLC)2 multi films improved wear life by 15 % and 36 %, respectively. The (Ti/Ti-DLC)2 multi film had the best corrosion resistance and wear life.

Regulating the ablation of nanoparticle-doped MAO coating on Mg alloy by MgF2 passivation layer construction

The corrosion of magnesium (Mg) alloys in various environments limits their practical applications in many fields. Incorporating corrosion-resistant nanoparticles in microarc oxidation (MAO) coating can enhance their corrosion resistance, but excess addition leads to high discharge voltage and coating ablation. In order to reduce the high discharge voltage, the structure of MAO passivation layer is regulated by using F- salts to generate low dielectric constant MgF2 phase. The results exhibit that several kinds of nanoparticles (Al2O3, SiO2, TiO2, ZnO, ZrO2) addition with high-content would not result in ablation due to the presence of MgF2. With the addition of high-content corrosion-resistant nanoparticles, the MAO coating demonstrates improved corrosion resistance. Especially the corrosion current density, it exhibits a reduction of approximately 2–3 orders of magnitude. This strategy of regulating the MAO passivation layer provides a novel approach for further enhancing the corrosion resistance of Mg alloy MAO coatings.

The effect of selected corrosion inhibitors on localized corrosion of magnesium alloy: The expanded understanding of "inhibition efficiency"

Research about magnesium corrosion inhibitors focuses on their influence on corrosion rate, but little attention is paid to whether the service reliability of alloys is improved by the inhibitors. In this work, the effects of selected corrosion inhibitors on the corrosion rate and localized corrosion behavior of magnesium alloy were compared. It is found that some corrosion inhibitors fail to inhibit the localized corrosion of magnesium, resulting in the inability to effectively maintain the mechanical bearing capacity of the corroded magnesium alloy. This study is of great significance for establishing reasonable screening and evaluation criteria for magnesium alloy corrosion inhibitors.

Enhancing corrosion resistance of AZ91D alloy through yttria-stabilized tetragonal zirconia (YSTZ)/MgO repaired ceramic coating with improved embrittlement cracking

The oxide ceramic coating for improving the corrosion of magnesium alloy remains challenging especially generated embrittlement cracking of the coating. A remarkable ameliorating embrittlement cracking behavior has been observed in this contribution on our developed yttria-stabilized tetragonal zirconia (YSTZ)/MgO repaired ceramic coating. It is related to stabilized specially oriented YSTZ grains affected by the (101) t-ZrO2 // (101) Y2O3 coherent interface and (101) YSTZ // (111) MgO semi-coherent interface continuous dislocation pinning. The high-quality repaired ceramic coating has few cracks after 48 h of immersion, which is expected to be beneficial to providing a suitable long-term protection to magnesium alloy.

Prediction of electrochemical corrosion behavior of magnesium alloy using machine learning methods

The corrosion of magnesium (Mg) alloys is a major challenge in many industrial applications because of their extreme reactivity, this greatly limits their applicability. The traditional methods in the prediction of corrosion rate depend on experimental or empirical models that can be time-consuming and expensive. Besides how to integrate experiments with faster machine-learning approaches is still a challenge of research. In recent years machine learning (ML) algorithms have proved and promised better magnesium corrosion predictability. In this study, different training algorithms such as linear regression (LR), decision tree (DT), extra tree (ET), random forest (RF), K-nearest neighbor (KNN), extreme gradient boosting (XGBoost), and Artificial Neural Network (ANN) were used to develop and predict corrosion rate of magnesium alloys based on magnesium chemical alloy composition as independent input variables. The data used for model preparation and validation were obtained from literature and experimental studies respectively. The feature selection methods were used to identify the most important and influential input parameters for magnesium alloy thus Shapley Additive Explanations (SHAP) interpretation was employed in this manuscript to facilitate feature visualization of the model. The results of the study show that the random forest (RF) algorithm has the greatest prediction impact than other machine learning algorithms. The magnesium alloy corrosion prediction model provides a better ability for the prediction of magnesium corrosion alloys. The study demonstrates the potential of ML models in the prediction of the corrosion behavior of Mg alloys and these models can be used to optimize an alloy composition for designing improved corrosion resistance of new Mg alloys.

Multisine impedimetric monitoring with an in-depth distribution of relaxation times analysis of WE43 and AZ31 magnesium alloys corrosion

This research aims to develop and utilize an impedance-based tool for monitoring non-stationary electrochemical processes, coupling the multisinusoidal perturbation signal approach and distribution of relaxation times (DRT) analysis for the first time. The approach was used to distinguish independent processes occurring at the surface of AZ31 and WE43 Mg alloys undergoing corrosion in Hank’s Balanced Salt Solution at 37 °C. We highlighted two common processes related to corrosion product layer formation. Detailed DEIS-DRT analysis was capable of real-time identification of a unique third process for the WE43 alloy, resulting from a spatially localized filiform corrosion attack in the vicinity of intermetallic particles. The proposed tool proved to be highly efficient in terms of studying non-stationary processes, while the DRT analysis allowed for an in-depth and precise localization of the number and the kinetics of the ongoing processes. The corrosion mechanism description was supported by numerous microscopic and spectroscopic tools.

Microstructure, Corrosion and Mechanical Properties of Magnesium Alloys

The properties of magnesium (Mg) and its alloys such as uniquely high specific strength (strength-to-density ratio), good castability, excellent machinability, adequate high-temperature formability and high damping capacity have garnered significant interest from researchers and product designers, especially in the automotive and aerospace industries, for many years [...]

Electrochemical, mechanical, and antibacterial properties of the AZ91 Mg alloy by hybrid and layered hydroxyapatite and tantalum oxide sol–gel coating

Abstract The corrosion and bacterial behavior of AZ91 magnesium alloy coated with sol–gel-deposited amorphous tantalum oxide and hydroxyapatite have been investigated. The objective was to assess the potential suitability of AZ91 for permanent prosthesis applications. The coatings were applied in layered and hybrid configurations and characterized using various techniques including X-ray diffractometry, Fourier transform infrared spectroscopy, scanning electron microscopy/energy dispersive spectrometry, and drop analyses. The antibacterial properties were evaluated through interactions with Staphylococcus aureus and Escherichia coli strains. Mechanical properties and adhesion were determined via linear scratch tests, and electrochemical corrosion tests were conducted in different media. The release of aluminum ions from the samples in Dulbecco’s Modified Eagle’s Medium was monitored over 28 days. The findings revealed that the amorphous tantalum oxide coating, particularly in combination with hydroxyapatite, improved antibacterial properties and positively influenced corrosion and scratch resistance. The layered and hybrid coatings demonstrated the highest corrosion resistance. The release of aluminum ions remained within acceptable levels in the tested medium. Overall, the study provides valuable insights into the potential of sol–gel coatings on AZ91 for prosthetic applications, considering antibacterial behavior, corrosion resistance, and aluminum release.

Corrosion and Protection of Magnesium Alloys: Recent Advances and Future Perspectives

Magnesium alloys are of significant importance for lightweight manufacturing and weight-saving applications due to their high weight-to-strength ratio and good mechanical properties. However, the poor corrosion resistance of Mg alloys limits their large-scale practical application. An essential theoretical foundation for the development of corrosion-resistant magnesium alloys and their surface protection technologies can be elucidated via the investigation of the corrosion mechanism of the magnesium surface and the alteration of the corrosion rate after surface conversion and coating. This paper discusses some typical corrosion behaviors by originally describing the corrosion mechanism of magnesium alloys with and without different coatings and surface treatments. In order to predict the future theoretical investigation and research directions for the surface protection of magnesium alloys, some techniques and preventative measures to enhance the corrosion resistance of magnesium alloys are reviewed, and these protection techniques are intercompared for better understanding.

The effect of addition of K2ZrF6 on the structures and properties of AZ31 magnesium alloy MAO coating

It is a challenge to improve the corrosion rate and blood compatibility of biomedical magnesium alloy implants in human body. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) were used to study the Properties of K2ZrF6 modified AZ31 magnesium alloy composite coating. The corrosion behavior of the sample in simulated body fluid (SBF) was evaluated by hydrogen evolution corrosion, potentiodynamic polarization cur ve and electrochemical impedance spectroscopy. The results show that the corrosion resistance of magnesium alloy is significantly improved by composite coating. The wettability test shows that K2ZrF6 greatly improves the biocompatibility of MAO coating on magnesium alloy. The hemolysis test shows that the composite coating makes magnesium alloy have low hemolysis rate. The increase of PH value and magnesium ion concentration in solution caused by corrosion of magnesium alloy can be adjusted by adding K2ZrF6. The corrosion resistance mechanism of MAO coating on K2ZrF6 modified magnesium alloy was discussed. In this experiment, the optimum amount of K2ZrF6 is 4 g/L.