Micro-arc Oxidation Layer Research Articles

Incorporation of Cerium Oxide Nanoparticles into the Micro-arc Oxidation Layer Promotes Bone Formation and Achieves Structural Integrity in Magnesium Orthopedic Implants

Biodegradable metals offer significant advantages by reducing the need for additional surgeries following bone fixation. These materials, with their optimal mechanical and degradable properties, also mitigate stress-shielding effects while promoting biological processes essential for healing. This study investigated the in vitro and in vivo biocompatibility of ZK60 magnesium alloy coated with a micro-arc oxidative layer incorporated with cerium oxide nanoparticles in orthopedic implants. The results demonstrated that the magnesium substrate undergoes gradual degradation, effectively eliminating long-term inflammation during bone formation. The micro-arc oxidative coating forms a dense ceramic layer, acting as a protective barrier that reduces corrosion rates and enhances the biocompatibility of the magnesium substrate. The incorporation of cerium oxide nanoparticles improves the tribological properties of the coating, refining degradation patterns and improving osteogenic characteristics. Furthermore, cerium oxide nanoparticles enhance bone reconstruction by facilitating appropriate interconnections between newly formed bone and native bone tissue. Consequently, cerium oxide nanoparticles contribute to favorable biosafety outcomes and exceptional bone remodeling capabilities by supporting bone healing and sustaining a prolonged degradation process, ultimately achieving dynamic equilibrium in bone tissue formation. Statement of SignificanceThis study comprehensively examined the incorporation of ceria nanoparticles into biodegradable magnesium through a micro-arc oxidative process for use in orthopedic implants. This study conducted a comprehensive analysis involving material characterization, biodegradability testing, in vitro osteogenesis assays, and in vivo implantation, highlighting the potential benefits of the distinctive properties of ceria nanoparticles. This research emphasizes the ability of ceria nanoparticles to enhance the biodegradability of magnesium and facilitate remarkable bone regeneration, suggesting promising advantages for additive materials in orthopedic implants.

Tailored micro-arc oxidation coatings to match with parylene for enhanced tribological performance of Ta-12W alloys

To improve the tribological properties of tantalum-tungsten alloys, dual-layer composite coatings are designed using micro-arc oxidation (MAO) and chemical vapor deposition (CVD) techniques. By adjusting the concentrations of NaOH and NaF additives as well as the oxidation mode (constant current/voltage) of MAO process, the microstructure and properties of underlying MAO layers are tailored for better matching with the top parylene layer, aiming to develop composite coatings capable of service under heavy loads. A comprehensive study is conducted to evaluate the effect of these parameters on the growth, microstructure, bond strength, and mechanical properties of MAO coatings, along with their subsequent impact on the friction and wear behavior under various loads for composite coatings. The findings reveal that increasing the concentration of either NaOH or NaF significantly increases the coating thickness, surface porosity, crystallinity, and hardness of MAO coatings, by promoting the spark discharge activities. However, distinct interfacial growth behavior is observed due to anionic effects caused by OH− and F−. The oxidation mode plays a crucial role in determining the mechanical quality of coatings; the constant voltage mode facilitates dense coatings with high adhesion due to its self-repairing mechanism. Furthermore, wear tests confirm that the enhanced mechanical properties and open-porosity of the MAO coatings markedly improve the tribological performance of composite coatings. This improvement is attributed to the excellent load-bearing capacity provided by hard MAO layers, as well as the anchoring and storage capabilities of the textural porous surfaces. The optimized composite coating demonstrates long-lasting low friction even under heavy loads up to 80 N.

Boosting corrosion resistance of Mg-Li alloy: Implanting bioinspired superhydrophobic surfaces into MAO matrix for enhanced protection

The corrosion problem has significantly impeded the practical application of Mg-Li alloys. In this report, a method that combines micro-arc oxidation (MAO) with electrochemical deposition is developed to create a superhydrophobic matrix on Mg-Li substrate. The combination approach harnesses the superiority of both coverages, including MAO as the dense, firmly bonded ceramic oxide layer on the metal substrate and the superhydrophobic surface (SHS) implanted into MAO matrix. The MAO-SHS coating exhibits high mechanical stability, maintaining the superhydrophobicity due to the “implanting effect” even after a long distance of friction effect. For corrosion inhibition, compared to the bare Mg-Li with icorr of 9.26 × 10−5 A/cm2, the icorr for MAO and MAO-SHS is 7.83 × 10−6 A/cm2 and 7.50 × 10−9 A/cm2, respectively, representing the reduction of approximately one and four orders of magnitude. Focusing the atmospheric corrosion inhibition, MAO-SHS proves to manipulate the dynamic evolution of saline solution evaporation and salt particle deliquation. The salt particle crystalized from saline solution on MAO-SHS is found to have significantly smaller contact area than that of the bare Mg-Li and MAO. By employing atomic force microscopy, the adhesion force of salt particle is revealed as ca. 45 nN, 13 nN, and 2 nN for salt particle on Mg-Li, MAO, and MAO-SHS, respectively. This suggests that the salt can be more easily removed from the MAO-SHS surface, thereby reducing the susceptibility to corrosion. The in situ deliquation is conducted to understand the formation of the droplet on different surfaces. The air in the SHS layer hinders chloride ingress and the SHS layer seals the pores in MAO layer, proving the synergistic effect afforded by MAO-SHS to achieve superior corrosion resistance.

Influence of titanium carbide particles on the characteristics of microarc oxidation layer on Ti6Al4V alloy

The Microarc Oxidation (MAO) layer on titanium alloy was mainly composed of TiO2, and there were some defects, such as holes and cracks, which made the performance of the MAO layer not ideal. To enhance the properties of the MAO layer, titanium carbide (TiC) particles were added to the electrolyte of a phosphate–silicate system as an additive. Consequently, the MAO layers containing the TiC phase on Ti6Al4V alloy were produced. The MAO process, composition, microstructure, and hardness of the MAO layer were comprehensively analyzed. Their frictional performance was assessed under reciprocating friction conditions without lubrication. The findings suggested that added TiC particles in the electrolyte played a significant role in creating the MAO layer, enhancing its thickness. The electrolyte without TiC particles produced an MAO layer primarily composed of TiO2 in two different mineral forms (rutile and anatase). Adding TiC particles resulted in the presence of TiC within the MAO layer, thereby facilitating the formation of a reinforced oxide layer. This addition also led to an improvement in the densification of the layer and a reduction in porosity. Notably, corrosion resistance testing indicated that incorporating 6 g l−1 TiC into the electrolyte resulted in superior performance compared with that obtained from the base electrolyte alone by achieving 1.4 times higher corrosion resistance. Moreover, a hardness value of 690 HV for the MAO layer was attained at a content level of 9 g l−1 TiC, demonstrating a significant 65% enhancement compared to the base oxide layer. This finding also demonstrated significantly enhanced friction property with a wear-volume reduction to 0.81 mm3. The findings on the relationship between the preparation of the MAO layer and its structure and properties can provide valuable guidance for designing and preparing the MAO layer.

A targeted vacuum-expansion sealing strategy for long-term protection of porous coatings

While surface treatments like anodic oxidation or micro-arc oxidation (MAO) significantly enhance the surface hardness and abrasion resistance of aluminum alloys, they often leave numerous dense pores or defects that compromise their corrosion resistance. Traditional sealing methods, such as boiling water or silane treatments, frequently fail to completely seal these micro-cavities and can introduce new defects due to volumetric shrinkage of the sealants, thereby reducing the service lifespan of the coatings. In this study, we introduce a novel vacuum-expansion sealing (VE sealing) strategy aimed at providing a more effective and durable sealing treatment. This method involves filling sealants in a vacuum environment, followed by volume expansion through ring-opening polymerization. Using this approach, the porosity of the porous MAO layer is significantly reduced, with the MAO-Ves coating porosity decreasing from 8.69 % to a remarkable 0.03 %. Electrochemical tests further demonstrate that after VE sealing, the sealed MAO sample maintains a higher low-frequency impedance |Z|0.01Hz of 1.16 × 107 Ω·cm2 after 672 h. This study not only presents a valuable strategy for enhancing the corrosion resistance of MAO coating, but also provides an efficient solution for improving the hardness, abrasion-resistance, and corrosion-resistance of surface-treated aluminum alloys and magnesium alloys.

Mao-based solid-like slippery composite coating with superior corrosion resistance and robust machinery performance upon magnesium-lithium alloy LA81

Slippery liquid-infused porous surface exhibits a great potential for corrosion management with super repulsive water properties, whilst their poor adhesion to underlying materials and durability of lubricants remains a challenge. In this work, a micro-arc oxidation (MAO)-based solid-like slippery composite coating (SSC) is developed upon Mg-Li alloy LA81 by combining mechanical pinning effects of MAO and super repulsive water performance of SSC, which maximizes adhesion strength, water repulsion and sustainable corrosion protection. The SSC coatings exhibit liquid-to-solid transition under the curing effect of epoxy resin. Efficient sealing of the MAO layer is yielded through high fluidity of the liquid phase of SSC. Cured SSC can further strengthen the interface bonding with respect to underlying MAO layer, and significantly alleviate lubricant loss.

Improvement of corrosion resistance of AZ31 magnesium alloy by laser remelting/microarc oxidation/LDH composite layer

Laser remelting (LR) pretreatment, micro-arc oxidation (MAO) treatment and layer double hydroxides (LDH) sealing post-treatment are conducted on AZ31 alloy surface in sequence. The results show that the corrosion resistance of prepared LR/MAO/LDH composite layer is significantly improved. Compared with the solution-aged AZ31 alloy and LR/MAO layer, the corrosion current densities of AZ31-LR/MAO/LDH were reduced by 4 and 2 orders of magnitude, respectively, and the self-corrosion potentials were increased by 1.23 V and 0.25 V, respectively. Laser remelting pre-treatment increased the average thickness of the MAO layer by 5–10 μm. LR/MAO/LDH composite layers can effectively improve the corrosion resistance of AZ31 alloy, and have the potential for application.

The effect of ultrasonic shot peening on micro-arc oxidation results of Ti-6Al-4V alloy

Micro-arc oxidation (MAO) is widely used in Ti‐6Al‐4V (TC4) alloy for surface modification and good biocompatibility in dental and orthopedic applications. However, it is a big challenge to produce thick MAO layers and nanoscale pores, both of which are crucial for biocompatibility. In this study, a new method called USMAO has been proposed, which involves performing USP as a pretreatment on the surface of TC4 before MAO. The results showed that USP could cause significant grain fragmentation and plastic deformation. After USMAO, composite architectures at the micron and nanoscale formed on the surfaces, and a thick MAO layer with a thickness of up to 30 µm could be also obtained, which was very useful for TC4 to enhance biocompatibility.

Synergistic effect of an organic hydrophobic film deposited on MAO containing NaH2PO4 for enhanced corrosion resistance of 6063 aluminum alloy

Aluminum alloys play a significant role in aviation, medical equipment, electronic device and automotive industry. Nevertheless, the corrosion is a critical problem that must be solved before applications. In this work, synergistic effect of an organic hydrophobic film (2-mercaptobenzothiazole (MBT), sodium stearate (SS) or 8-hydroxyquinoline (8-HQ)) deposited on micro-arc oxidation (MAO) which was post-sealing treated by NaH2PO4 was investigated on corrosion resistance. The morphology and composition of the resulting organic hydrophobic films were analyzed by FESEM, EDS and FTIR. The results revealed that the organic hydrophobic films were successfully deposited on the MAO coating with NaH2PO4 (MAO-NaH2PO4), and the pores and cracks of the MAO layer were effectively sealed. Moreover, the contact angle of the sample with 8-HQ treating reached the hydrophobic level (136.8°), which was much higher than that of the MAO-NaH2PO4 (58.06°). The PDP and EIS measurements showed that the sample with 8-HQ treating possessed superior corrosion resistance with a low corrosion current (1.924 × 10−8 A cm−2) and the decreased corrosion rate (1.8 × 10−4 mm·a−1), which was two order of magnitude higher than that of the MAO-NaH2PO4 sample (3.8 × 10−2 mm·a−1). This facile and low-cost strategy to form organic-inorganic composite coatings could have promising application in the corrosion protection for the light alloys.

Study on corrosion protection behavior of magnesium alloy/micro-arc oxidation coating in neutral salt spray environment

To study the corrosion behavior of wrought and cast Mg alloys protected by a micro-arc oxidation layer, a neutral salt spray test was used to accelerate the corrosion of the samples. The results showed that the surface of the wrought Mg alloy/micro-arc oxidation system was relatively smooth up to 720 h, and there was no obvious change in the alloy. However, the corrosion products were observed on the surface after 960 h. Corrosion products appeared in the cast Mg alloy/micro-arc oxidation system after 240 h of testing. Electrochemical impedance spectroscopy results and failure analyses of the scratched samples indicated that in the early stage of corrosion, a large number of corrosion products were formed on the substrate and accumulated in the micro-arc oxidation layer, which blocked the pores and gradually enhanced the impermeability of the two Mg alloys/micro-arc oxidation systems. After 480 h, the impermeability of the micro-arc oxidation layer in the cast Mg alloy/micro-arc oxidation system decreased as the number of pores, cracks, and other defects in the layer increased. This resulted in a decrease in the damage position of the micro-arc oxidation layer.

Effect of Surface Activation on the Corrosion Resistance of a MAO/Ni-P Composite Coating on LZ91 Magnesium Alloy

BackgroundLZ91 Magnesium alloy with a dual-phase structure has improved mechanical properties and a low density of about 1.48 g/cm3 but their limited resistance to corrosion limits their application. Therefore, it is a great challenge to increase the stability of LZ91 alloys under corrosive factors and environments. MethodsThis study uses micro-arc oxidation (MAO) and an electroless nickel-phosphorus (Ni-P) plated composite film to increase the corrosion resistance of LZ91 magnesium alloy. Before electroless Ni-P plating, the MAO layers are activated by palladium catalysts at different pH values to produce composite coatings. SEM, EDS and Image J are used to determine the surface properties and elemental composition of the samples. The corrosion resistance is measured using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. FindingsThe results show that the MAO coating is activated by an acid catalyst and the surface is obviously corroded. The electroless Ni-P plating grows into the MAO coating and the substrate corrodes. Therefore, corrosive medium (chloride ion) easily enter to the substrate and pitting corrosion occurred. On the contrary, activation by a neutral catalyst (pH=7) maintains the original structure of the MAO coating and provides a good bonding interface for the Ni-P coating. Form the potentiodynamic analysis can be finds that the corrosion potential for the neutral catalyst treated sample is -0.35V and the corrosion current density value is 1.77×10−6 A/cm2, so the corrosion characteristic become better than the acid catalyst treated samples. In terms of the long-term resistance after 48 h, EIS analysis shows that the resistance value remains at about 7.6×104 Ω•cm2. A composite coating that is compact and with excellent resistance to corrosion resistance is produced, which provides better protection for LZ91 magnesium alloys.

Preparation and mechanical and biological performance of the Sr-containing microarc oxidation layer on titanium implants

A Strontium-doped titanium oxide coating was successfully prepared on a TA4 substrate with one-step microarc oxidation (MAO) technology. Then bioactivity of the coating was performed with the inducation test of bone-like apatite formation immersed in simulated body fluid (SBF). The biological activity of the coating was evaluated with cell culture experiments, and its corrosion resistance was characterized with electrochemical tests in the SBF. The composition and morphology of the coatings before and after SBF immersion were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that the coating had a rough porous structure, which was mainly composed of anatase, rutile and Ti phases. The SBF immersion test showed that abundant 3D micro nanopore structures were formed on the surface of the porous titanium oxide coatings, which enabled the coatings to exhibit good apatite nucleation ability. Faster precipitation of bone-like apatite by MAO-Sr coatings in SBF. Finally, in the biological compatibility test, compared with TA4, the contact angle between the MAO-Sr coating and SBF solution was lower, and the proliferation ability of bone marrow stromal cells (BMSCs) in the biological coating was stronger, indicating the good biocompatibility of the coating.

ZIF-8-based micro-arc oxidation composite coatings enhanced the corrosion resistance and superhydrophobicity of a Mg alloy

Mg alloys are considered the most promising engineering materials because of their unique properties. However, the uncontrolled corrosion rate of these alloys limits their applications. Therefore, in this study, a micro-arc oxidation layer was used as a transition layer to “directly” grow a zinc-based metal-organic framework (MOF) composite coating on the surface of a Mg alloy (AZ91D). Herein, the two zeolitic imidazolate framework (ZIF-8) coatings with different morphologies were separately prepared by homologous metal oxide induction and a one-step in-situ growth method. The superhydrophobic composite coating showed strong hydrophobicity and self-cleaning properties, which could prevent the penetration of water and corrosive ions (Cl−) into the surface of AZ91D. Electrochemical tests demonstrated that the super-hydrophobic composite coatings greatly enhanced the corrosion resistance of AZ91D, and the corrosion current density decreased from 10−5 to 10−9 A/cm2. These results indicate that the ZIF-8 coatings are beneficial for improving the hydrophobicity and enhancing the corrosion resistance of Mg alloys. Therefore, MOF composite coatings provide a new strategy that can be used to prepare multifunctional anticorrosion coatings on metal substrates.

Surface Characterization of New β Ti-25Ta-Zr-Nb Alloys Modified by Micro-Arc Oxidation.

The technique of surface modification using electrolytic oxidation, called micro-arc oxidation (MAO), has been used in altering the surface properties of titanium alloys for biomedical purposes, enhancing their characteristics as an implant (biocompatibility, corrosion, and wear resistance). The layer formed by the micro-arc oxidation process induces the formation of ceramic oxides, which can improve the corrosion resistance of titanium alloys from the elements in the substrate, enabling the incorporation of bioactive components such as calcium, phosphorus, and magnesium. This study aims to modify the surfaces of Ti-25Ta-10Zr-15Nb (TTZN1) and Ti-25Ta-20Zr-30Nb (TTZN2) alloys via micro-arc oxidation incorporating Ca, P, and Mg elements. The chemical composition results indicated that the MAO treatment was effective in incorporating the elements Ca (9.5 ± 0.4 %atm), P (5.7 ± 0.1 %atm), and Mg (1.1 ± 0.1 %atm), as well as the oxidized layer formed by micropores that increases the surface roughness (1160 nm for the MAO layer of TTZN1, 585 nm for the substrate of TTZN1, 1428 nm for the MAO layer of TTZN2, and 661 nm for the substrate of TTZN2). Regarding the phases formed, the films are amorphous, with low crystallinity (4 and 25% for TTZN2 and TTZN1, respectively). Small amounts of anatase, zirconia, and calcium carbonate were detected in the Ti-25Ta-10Zr-15Nb alloy.

Effect of Ti3SiC2 and Ti3AlC2 Particles on Microstructure and Wear Resistance of Microarc Oxidation Layers on TC4 Alloy.

Microarc oxidation (MAO) layers were prepared using 8g/L Na2SiO3 + 6g/L (NaPO3)6 + 4g/L Na2WO4 electrolyte with the addition of 2g/L Ti3SiC2/Ti3AlC2 particles under constant-current mode. The roughness, porosity, composition, surface/cross-sectional morphology, and frictional behavior of the prepared MAO layers were characterized by 3D real-color electron microscopy, scanning electron microscopy, X-ray energy spectrometry, X-ray diffractometry, and with a tribo-tester. The results showed that the addition of Ti3SiC2 and Ti3AlC2 to the electrolyte reduced the porosity of the prepared layers by 9% compared with that of the MAO layer without added particles. The addition of Ti3SiC2/Ti3AlC2 also reduced the friction coefficient and wear rate of the prepared layers by 35% compared with that of the MAO layer without added particles. It was found that the addition of Ti3AlC2 particles to the electrolyte resulted in the lowest porosity and the lowest wear volume.

Facile fabrication of continuous graphene nanolayer in epoxy coating towards efficient corrosion/wear protection

A combination of graphene and resin has been recognized as a good strategy for anti-corrosion and anti-wear applications. However, the discontinuity of shielding layer and lubricating film restricts the performance enhancements of graphene/epoxy coating. Hence, to maximize the structure and property advantages of graphene, a continuous graphene nanolayer with parallel distribution was fabricated in the epoxy coating by the Marangoni effect. Meanwhile, the introduction of microarc oxidation layer enhances the adhesion strength of epoxy coating and prevents galvanic corrosion of graphene. The multilayer coating exhibits a large enhancement of lowest-frequency impedance value increased by two orders of magnitude and excellent long-term chlorine resistance, with pure epoxy coating as a comparison, attributing to the outstanding barrier effect of multilayer structure and continuous impermeable graphene layer to corrosion media. Meanwhile, its wear rate (6.94 × 10−8 mm3/N·mm) is decreased by 43.11% compared with pure epoxy coating (1.22 × 10−7 mm3/N·mm) due to the graphene layer preventing the counterpart ball from directly contacting the epoxy coating and providing easy shear in the contact interface. Therefore, the as-prepared multilayer coating with excellent anti-corrosion and anti-wear properties has great application prospects in the corrosion and wear fields.

Final surface modification for better wear resistance of ceramic coating on cast AlSi10Mg alloy

Using the design of experiment (DOE) method and the micro-arc oxidation (MAO) technique, ceramic layers on AlSi10Mg alloy were systematically prepared to design optimal process conditions for achieving the best tribological properties of the ceramic layers. The lowest concentrations of the applied 6 g/l NaOH and 12 g/l Na 2 SiO 3 resulted in the preparation of uniform MAO layers with the lowest rated parameters R a , R z and thickness achieved under micro-arc discharge conditions at 500 V and 60 min. With the increasing thickness of the coatings, there was an increase of Si in the MAO coating. Full factorial DOE was used to optimize the tribological properties in a polyalphaolefin (PAO) environment at 80 °C. The most significant influence for the preparation of abrasion-resistant layers for the investigated factors was identified on the AlSi10Mg alloy by the NaOH content in the electrolyte. The friction coefficients of MAO coatings reached an average value of 0.15. Aero-lap polishing technology was applied for increased wear resistance requirements to eliminate the deficiencies of MAO coatings, leading to decrease wear track by almost double compared to polished silumin. Removal of the outer MAO layer by polishing led to a reduction in the high corrosion resistance of the MAO coating, demonstrating the influence of the outer layer not only on the tribological properties but also on the corrosion resistance of MAO coatings.

Effect of graphene oxide on corrosion resistance and biological activity of micro arc oxidation ceramic layer on titanium alloy

• The adhesion between ceramic layer prepared by two-step MAO and substrate is fine. • When GO content is 0.112 g/L, the adhesion between MAO layer and substrate is higher. • The corrosion resistance is improved by adding GO and it is related to GO content. • CaP-0.112GO sample has highest polarization resistance and best corrosion resistance. • GO added increases ion exchange rate and improves biological activity of MAO layer. The calcium-phosphorus ceramic layer is prepared on titanium alloy by two-step micro-arc oxidation (MAO). The effect of graphene oxide (GO) on microstructure, corrosion resistance and biological activity of MAO layer was studied. The MAO layer surface is rough and porous. When GO is added 0.112 g/L, the corrosion resistance of MAO layer and the adhesive force between MAO layer and substrate are higher. GO added improves the biological activity of MAO layer.

The influence of alloy microstructure on corrosion resistance and other properties of coatings formed by microarc oxidation

The influence of the initial microstructure of the aluminium alloy Al–12Si on the corrosion resistance of the microarc oxidation (MAO) coating has been studied. It has been established that the corrosion rate of samples with MAO-coating on an alloy with an ultrafine-grained (UFG) structure increases by 5.6 ... 11.6 times depending on the modes of the MAO process in relation to samples with a coating, but with a coarse-grained structure. It is assumed that this effect is associated with unrecorded small-scale porosity, the proportion of which in the MAO layer on samples with an UFG structure is higher.

Superhydrophobic composite coating for reliable corrosion protection of Mg alloy

Endowing Mg alloy surface with superhydrophobicity solves its poor corrosion resistance for broadening the wide application fields. However, the superhydrophobicity is vulnerable to failure under service environments due to the exfoliation and degradation of surface material. Hence, a bilayer composite coating composed of microarc oxidation layer and superhydrophobic layer was fabricated to protect Mg alloys by modulating superhydrophobic coating/substrate interface. The bilayer coating with a water contact angle of 158.3° possesses excellent water-repellent, and self-cleaning properties. In addition, the bilayer coating consistently remains superhydrophobicity in acid, alkaline, high/low temperature, and ultraviolet radiation environments, indicating the excellent environmental stability. Notedly, the lowest-frequency impedance value of bilayer coating (6.78 × 106 Ω·cm) increases five orders of magnitude compared with that of Mg alloy (60.2 Ω·cm), and the inhibition efficiency is calculated to be 99.99 %. The excellent corrosion resistance of coating is attributed to the synergistic barrier protection of microarc oxidation layer and superhydrophobic layer, implying that it provides effective protection for Mg alloy. Therefore, the as-prepared bilayer coating has great application prospects in corrosion protection of Mg alloys toward different service environments.