Corrosion Resistance Of Mg Alloy Research Articles

The performance of hybridized nano-ceramics on the microstructure and corrosion of Mg alloy in an auto-engine cooling system

This current novel research focuses on developing a hybrid magnesium-based composite through the spark plasma sintering process with an interest in the improvement of mechanical properties and corrosion resistance of Mg Alloy in an auto-cooling system. AZ91D was selected as the primary Mg alloy and it was reinforced with hybridized AlN-VB at a sintering temperature of 500 °C, a heating rate of 75 °C/min, a pressure of 30 MPa, and a dwell time of 5 min. The microstructure of the sintered composite at varying weight constituents shows a homogenous dispersion of the reinforcing material and refinement of the inherent eutectic β-Mg17Al12 phase. The refinement of the phase yielded a small grain size of 16.6 ± 0.20 μm by the MgAZ91D-8wt%AlN-8wt%VB composite compared to the coarse grain size of 36.1 ± 0.9 μm by the unreinforced MgAZ91D. likewise, a higher microstrain value of 7.57E-2 was achieved by the composite with the highest reinforcing constituents. The load-displacement curve shows a gradual shift to the left following the inclusion of the reinforcing substances, this implies a higher resistance to penetration as a result of higher nanohardness and elastic modulus. The corrosion behavior of the sintered composite was examined in a simulated auto-engine cooling system using ethylene-glycol and corrosive water. The Unreinforced MgAZ91D shows a high corrosion rate (Cr) of 2.2217 mm/year, a higher degree of disorderliness (n) of 0.8829, and a low charge resistance transfer (Rct) of 4.6143 kΩcm2. However, the corrosion rate decreases rapidly to 0.0475 mm/year and the Rct to 20.9543 kΩcm2 at MgAZ91D-8wt%AlN-8wt%VB composite.

Surface Heparinization of a Magnesium-Based Alloy: A Comparison Study of Aminopropyltriethoxysilane (APTES) and Polyamidoamine (PAMAM) Dendrimers.

Magnesium (Mg)-based alloys are biodegradable metallic biomaterials that show promise in minimizing the risks of permanent metallic implants. However, their clinical applications are restricted due to their rapid in vivo degradation and low surface hemocompatibilities. Surface modifications are critically important for controlling the corrosion rates of Mg-based alloys and improving their hemocompatibilities. In the present study, two heparinization methods were developed to simultaneously increase the corrosion resistance and hemocompatibility of the AZ31 Mg alloy. In the first method, the surface of the AZ31 alloy was modified by alkali-heat treatment and then aminolyzed by 3-amino propyltriethoxy silane (APTES), a self-assembly molecule, and heparin was grafted onto the aminolyzed surface. In the second method, before heparinization, polyamidoamine dendrimers (PAMAM4-4) were grafted onto the aminolyzed surface with APTES to increase the number of surface functional groups, and heparinization was subsequently performed. The presence of a peak with a wavelength of about 1560 cm-1 in the FTIR spectrum for the sample modified with APTES and dendrimers indicated aminolysis of the surface. The results indicated that the corrosion resistance of the Mg alloy was significantly improved as a result of the formation of a passive layer following the alkali-heat treatment. The results obtained from a potentiodynamic polarization (PDP) test showed that the corrosion current in the uncoated sample decreased from 25 µA to 3.7 µA in the alkali-heat-treated sample. The corrosion current density was reduced by 14 and 50 times in samples treated with the self-assembly molecules, APTES and dendrimers, respectively. After heparinization, the clotting time for pristine Mg was greatly improved. Clotting time increased from 480 s for the pristine Mg sample to 630 s for the APTES- and heparin-modified samples and to 715 s for the PAMAM- and heparin-modified samples. Cell culture data showed a slight improvement in the cell-supporting behavior of the modified samples.

Enhanced anti-corrosion/wear properties of Mg alloy through a hierarchical bio-inspired self-healing composite coating

The poor anti-corrosion/wear property of magnesium (Mg) alloys has limited their industrial applications. This paper reports a hierarchical bio-inspired composite coating on Mg alloy surface, through a spray/spin assisted self-assembly process, which overcomes the difficulty in coordination of the self-healing and wear resistance ability, realizing an enhanced self-healing and anti-corrosion/wear ability. The nitrogen-ligated boroxine cross-linked polydimethylsiloxane (N-B-PDMS) and the blend solution of reduced graphene oxide (RGO) and polyvinyl alcohol (PVA) are used to construct the protective hard top layer and self-healing down layer, respectively, obtaining an N-B-PDMS@RGO/PVA (B@RGO/PVA) coating. A large number of reversible covalent boroxine(B3O3)/hydrogen bonding networks are formed within the coating, leading to a compact hierarchical composite structure. The results show that the scratch is miraculously repaired within 1.5 min due to the reversible chemical bonding of N-B-PDMS coating, while its tight three-dimensional network structure significantly restore the corrosion resistance of Mg alloy. The wear resistance of N-B-PDMS extremely promotes two orders of magnitude, derived from the high hardness and low friction coefficient of PVA/RGO shell, and further improves the anti-corrosion through this layer-by-layer barrier structure. Owing to the intensive self-healing ability of typical boroxine cross-linked microstructure, artificial damage of B@RGO/PVA coating can be rapidly repaired after 5 min, which surpasses almost the vast majority of previously reported self-healing materials, and therefore the long-term corrosion resistance is almost completely recovered. In this hierarchical microstructure, the top layer and the down layer complement each other to form a multi-functional coating with ultra-fast self-healing and superior corrosion/ wear resistance, which has guiding significance for the design and construction of multifunctional protection coatings for Mg alloy or other metallic materials.

Synthesis of Ni-WC/Al-Ni functionally graded coating with advanced corrosion and wear resistance on AZ91D Mg alloy by laser cladding

The low hardness and poor wear and corrosion resistance of Mg alloys restrict their further applications. Laser cladding technology has been employed to prepare coatings on metals and alloys, but owing to the low melting point of Mg alloy, it is difficult to clad high-performance coatings that usually have high melting points directly. To achieve superior corrosion and wear resistance, a Ni–WC/Al–Ni functionally graded coating was designed and prepared on AZ91D Mg alloy. The microstructure, hardness, corrosion resistance, and tribological behaviors of the coating were studied. The results showed that good metallurgical bonding was obtained between the coating layers and substrate. The Ni–WC top-layer had excellent mechanical performance, and corrosion and wear resistance. The wear resistance of the top-layer was 5–8 times that of the substrate and contributed to the simultaneous enhancement of hardness and corrosion resistance. The results suggest that the use of a functionally graded prepared coating is a good strategy to form a high-performance coating on Mg alloy.

Interaction of elements in dilute Mg alloys: a DFT and machine learning study

The solution behavior of alloying elements is crucial for the design of Mg alloys. The plasticity, strength and corrosion resistance of Mg alloys can be tailored by alloying elements in solid solution in the primary Mg phase. In this work, the interaction and solution behavior of 24 alloying elements in Mg alloys, including 24 binary systems and 88 ternary systems, was studied. Features characterizing the interactions of solute elements in the primary Mg phase, including atomic substitutional sites, volume difference, c/a ratio and formation energy, of these alloys were calculated by first principles. Relations between the interaction features and the alloying elements’ characteristics were constructed based on machine learning methods, in which strong correlations were observed. Additionally, the electronic and atomic origin of the interaction features in solid solution ternary Mg alloys were analyzed. This work provides new insights into the design of high-performance multicomponent Mg alloys, as well as the construction of atomic models for other alloys.

A REVIEW ON UNDERSTANDING OF CORROSION AND PROTECTION STRATEGIES OF MAGNESIUM AND ITS ALLOYS

There remains a keen concern in magnesium (Mg) and its alloys, as they are the lightest available structural materials. Mg alloys are capable of allowing the design of lightweight engineered systems, including encouraging implications to curtail energy consumption. These alloys are also evolving available biodegradable materials and battery electrodes. Instead of the extreme historical Mg usage at present, several intrinsic drawbacks, including susceptibility to corrosion, poor formability, and low creep strength limit the extensive use of Mg alloys. This review provides an overview of ancient to modern advances in the study of Mg corrosion. It describes the effects of alloying elements and reinforcement in metal matrix composites (MMCs) on the corrosion resistance of Mg alloys. The frequent use of protective strategies and their limitations are discussed from the recent past to the current trend. This review is recognizing acquaintance gaps while also endeavoring to ascertain planned developments and guidelines.

A review on magnesium alloys for application of degradable fracturing tools

The vulnerable corrosion resistance of Mg alloys is regarded as one of the main disadvantages restricting their application, while it can be used as an extraordinary specialty in some particular fields, such as petroleum exploitation and medicine. In recent years, many Mg alloys with high corrosion rate and high strength have been developed for fracturing temporary plugging tools in the oil exploitation. This review briefly introduces the performance requirements of the degradable fracturing tools classified into mechanical and corrosion properties. Recent progress on corrosion behavior of degradable Mg-Al, Mg-Zn, Mg-RE alloys and Mg matrix composites is then summarized and discussed. Finally, the factors influencing the degradation rate of Mg alloys are analyzed and divided into secondary phase, texture, dislocation, grain size and surface film. From the summary, it can be found that addition of Ni or Cu to the degradable Mg alloys is a common and effective method to enhance the degradation rate due to increasing the amount of secondary phases and deteriorating the corrosion product layers. For the as-extruded degradable Mg alloys, grain size, texture and dislocation are the key factors affecting the corrosion rate under different processing conditions. We expect this review is helpful for those who are working on developing Mg-based functional materials with superior degradation rate.

Review: Degradable Magnesium Corrosion Control for Implant Applications.

Magnesium (Mg) alloys have received increasing interest in the past two decades as biomaterials due to their excellent biological compatibility. However, the corrosion resistance of Mg alloys is relativity low which limits their usage in degradable implant applications, and controlling the corrosion resistance is the key to solving this problem. This review discusses the relative corrosion mechanisms, including pitting, filiform, high temperature, stress corrosion, etc., of Mg alloys. Various approaches like purification (Fe, Ni, Cu, etc.), micro-alloying (adding Zn, Mn, Ca, RE elements, and so on), grain refinement (severe plastic deformation, SPD, etc.), and surface modifications (various coating methods) to control corrosion and biological performance are summarized. Moreover, the in vivo implantations of Mg alloy vascular stents and the issues that have emerged based on the reports in recent years are introduced. It is recommended that corrosion mechanisms should be further investigated as there is no method that can remove all the impurities and a new purification approach needs to be developed. The concentration of micro-alloy elements should be carefully controlled to avoid superfluous compounds. Developing new continuous SPD methods to achieve fine-grained Mg alloys with a large size scale is necessary. The development of a multifunctional coating could also be considered in controlling the Mg degradation rate. Moreover, the research trends and challenges in the future of Mg biomaterials are proposed.

A review on magnesium alloys for biomedical applications.

Magnesium (Mg) and Mg alloys are considered as potential candidates for biomedical applications because of their high specific strength, low density, and elastic modulus, degradability, good biocompatibility and biomechanical compatibility. However, the rapid corrosion rate of Mg alloys results in premature loss of mechanical integrity, limiting their clinical application in load-bearing parts. Besides, the low strength of Mg alloys restricts their further application. Thus, it is essential to understand the characteristics and influencing factors of mechanical and corrosion behavior, as well as the methods to improve the mechanical performances and corrosion resistance of Mg alloys. This paper reviews the recent progress in elucidating the corrosion mechanism, optimizing the composition, and microstructure, enhancing the mechanical performances, and controlling the degradation rate of Mg alloys. In particular, the research progress of surface modification technology of Mg alloys is emphasized. Finally, the development direction of biomedical Mg alloys in the future is prospected.

Enhanced long-term corrosion resistance of Mg alloys by superhydrophobic and self-healing composite coating

Although Magnesium (Mg) alloys have many distinct advantages, they are vulnerable to the corrosion even in the neutral environment. Effective and feasible anti-corrosion strategies are desirable for the wide application of Mg alloys. A novel anti-corrosion composite coating, MAO (micro-arc oxidation)/[OTP][NTf2] (octadecyl triphenyl phosphonium bis(trifluoromethylsulfonyl)amide)/PSE (superhydrophobic silica/epoxy resin), is fabricated for Mg alloys by combination of MAO, ionic liquid, and superhydrophobic coating. The employed [OTP][NTf2] is incorporated into the pores of MAO coating rather than doped in the PSE coating. The successful preparation of composite coating is characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-corrosion feature is measured by potentiodynamic polarization curves (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5 wt% NaCl solution. The composite coatings maintain excellent corrosive resistance after 80 days immersion in 3.5 wt% NaCl solution. It is attributed to the synergistic effect of the superhydrophobic feature, the corrosion inhibition of [OTP][NTf2], and the physical barrier of the MAO coating. Even if the coating is scratched, it still exhibits the excellent anti-corrosion performance after immersion in 3.5 wt% NaCl solution for 25 days due to the repair ability of [OTP][NTf2]. The incorporation of [OTP][NTf2] not only offers the self-healing feature but also seals the pores on the MAO surface, which is favorable to enhance the overall anti-corrosion performance of composite coating.

Fabrication of electroactive poly(γ‐glutamic acid) coating for improving corrosion resistance and cytocompatibility of magnesium alloy

AbstractAlthough magnesium (Mg) and its alloys are promising biodegradable materials for orthopedic implants, rapid and uncontrollable degradation of Mg is still a challenge for clinical applications. In this work, electroactive polymer coatings were prepared to improve the corrosion resistance and cytocompatibility of Mg alloys. Amphiphilic electroactive tetraaniline (TANi)‐conjugated poly(γ‐glutamic acid) (γ‐PGA) with various TANi modification rates (γ‐PGA–TANi10, γ‐PGA–TANi20, γ‐PGA–TANi27) were first synthesized. γ‐PGA–TANi colloidal particles, prepared by a self‐assembly method, were then coated on Mg alloys by electrophoretic deposition. The prepared γ‐PGA–TANi coatings showed a homogeneous surface and good adhesion on AZ31 Mg alloys. Electrochemical analysis and in vitro immersion tests revealed that γ‐PGA–TANi‐coated Mg exhibited superior corrosion resistance, which was mainly attributed to the electroactivity of the γ‐PGA–TANi coatings, leading to the rapid formation of a passivation layer to prevent the further corrosion of Mg alloys. Furthermore, the γ‐PGA–TANi alloy coatings efficiently regulated Mg2+ release and pH value of coated Mg alloy during immersion for 40 days. In comparison with bare Mg alloy, the coated Mg alloy also showed better cytocompatibility, where L929 cells emerged with a good cell adhesion and viability. These results indicate that electroactive γ‐PGA–TANi coatings have promising potential for corrosion resistance of Mg alloys. © 2022 Society of Industrial Chemistry.

Corrosion behavior and mechanism of Mg–Er–Zn–Zr alloys in different states

The corrosion behavior and mechanism of as-cast, solid-solution treated, and as-extruded Mg-14.4Er-1.4Zn-0.3Zr (wt.%) alloys are investigated. The microstructure characteristic of as-cast alloy, i.e., the semi-continuous 18R-long period stacking ordered (LPSO) phase as cathode with the potential difference (PD) of 83 mV, is the main reason for the relatively strong tendency of micro-galvanic corrosion. The lower micro-galvanic tendency by the decreased size, number, and PD (30 mV) of LPSO-phase particles, and the existence of a few Er3+ in corrosion film, are mainly responsible for the improved corrosion resistance of solid-solution treated alloy. The as-extruded alloy exhibits a superior corrosion resistance (corrosion rate: 1.11 mm y−1 in 3.5 wt.% NaCl solution) as compared to many reported Mg alloys, which mainly attributed to the formation of nano-spaced basal plane solute-enriched stacking faults (SESFs) within fine dynamic recrystallized (DRXed) grains. The nano-scale SESFs as the weak anode with PD of 26 mV weaken the galvanic tendency to form a relatively homogeneously electrochemical microstructure. Moreover, the preferential corrosion of SESFs releases sufficient Er3+, promoting the quasi-passivation state of corrosion film. The construction of weak anodic nano-lamellar SESFs structure within fine grains is a feasible method for the synergetic improvement of strength and corrosion resistance of Mg alloys.

Effect of asymmetric rolling on corrosion behaviour of AZ31B magnesium alloy sheet

In this study, symmetric rolling (SR), unidirectional asymmetric rolling (UASR) and reverse asymmetric rolling (RASR) were conducted in AZ31B alloy, and the corrosion behaviour of AZ31B alloy deformed via these processes mentioned above were studied. The results indicated that samples deformed via the RASR process exhibited a more homogeneous microstructure with refined grains. As a result, samples deformed via the RASR process had the highest open circuit potential (OCP), corrosion potential (E corr) and the lowest corrosion current density (i corr) , underwent slightly localised corrosion, suggesting that the RASR process is beneficial to improve the corrosion resistance of Mg alloy.

Oxyhydroxide-Coated PEO–Treated Mg Alloy for Enhanced Corrosion Resistance and Bone Regeneration

Plasma electrolytic oxidation (PEO) is widely used as a surface modification method to enhance the corrosion resistance of Mg alloy, the most likely applied biodegradable material used in orthopedic implants. However, the pores and cracks easily formed on the PEO surface are unfavorable for long-term corrosion resistance. In this study, to solve this problem, we used simple immersion processes to construct Mn and Fe oxyhydroxide duplex layers on the PEO-treated AZ31 (PEO–Mn/Fe). As control groups, single Mn and Fe oxyhydroxide layers were also fabricated on PEO (denoted as PEO–Mn and PEO–Fe, respectively). PEO–Mn showed a similar porous morphology to the PEO sample. However, the PEO–Fe and PEO–Mn/Fe films completely sealed the pores on the PEO surfaces, and no cracks were observed even after the samples were immersed in water for 7 days. Compared with PEO, PEO–Mn, and PEO–Fe, PEO–Mn/Fe exhibited a significantly lower self-corrosion current, suggesting better corrosion resistance. In vitro C3H10T1/2 cell culture showed that PEO–Fe/Mn promoted the best cell growth, alkaline phosphatase activity, and bone-related gene expression. Furthermore, the rat femur implantation experiment showed that PEO–Fe/Mn–coated Mg showed the best bone regeneration and osteointegration abilities. Owing to enhanced corrosion resistance and osteogenesis, the PEO–Fe/Mn film on Mg alloy is promising for orthopedic applications.

Influence of 2,6-dihydroxybenzoic acid on the corrosion behavior and discharge performance of AZ31 Mg alloy

The influence of different concentrations of 2,6-dihydroxybenzoic acid (2,6-DHB) on corrosion performance and discharge properties of AZ31 Mg alloy is studied by means of EIS, potentiodynamic polarization and half-cell discharge test. It was found that low concentration of 2,6-DHB (0.01 M) can enhance the corrosion resistance of Mg alloy, since it acts as complexing agent to decrease the self-corrosion rate and suppress cathodic hydrogen reaction. High amount of additive in NaCl solution accelerates the dissolution rate of the substrate, leading to deteriorated corrosion performance. The discharge properties of the Mg anode have been greatly modified by the presence of 2,6-DHB. 76.86% of utilization efficiency and 1668.17 mAh g−1 of specific capacity have been achieved for AZ31 Mg alloy in 3.5 wt % NaCl solution with addition of 0.01 M organic additive. High amount of complexing agent promotes self-corrosion and dissolution rate of the substrate, which is detrimental to the discharge properties of the anode.

Effect of crystallographic texture and twinning on the corrosion behavior of Mg alloys: A review

Magnesium and its alloys have gained significant popularity due to their light weight and their potential for use as bioresorbable materials. However, their application is limited in practice due to their relatively poor corrosion resistance. Several methods are available for improving the corrosion resistance of Mg alloys for bio-applications such as using different coatings, alloying, and modifying the microstructural parameters such as the grain size and the crystallographic texture. This review provides a comprehensive summary of the effects of crystallographic texture and twinning, as one of the most important deformation mechanisms of Mg and Mg alloys, on the corrosion behavior. Regarding the crystallographic texture, it is shown that theoretically the basal planes should exhibit a lower corrosion rate but in some cases, such as when there is a galvanic effect or when corrosion films control the overall corrosion behavior, different results may take place. Also, there are contradictory results concerning the effect of twinning on the corrosion behavior. Thus, in some cases twinning may provide preferential sites for corrosion due to the higher energies of atoms located in the twin region by comparison with normal atomic positions in the crystalline lattice whereas there are also other examples where experiments show that twins produce more protective films than in the surrounding matrix.

Enhancing the Corrosion Resistance of Low Pressure Cold Sprayed Metal Matrix Composite Coatings on AZ31B Mg Alloy through Friction Stir Processing

To improve the corrosion resistance of Mg alloy, Al alloy/alumina metal matrix composite (MMC) coatings were formed by low pressure cold spraying (LPCS) technology followed by post friction stir processing. The phase structure, microstructure, and corrosion properties of the cold-sprayed metal matrix composite coatings before and after friction stir processing were investigated. The effect of the friction stir process (FSP) on the corrosion characteristics of MMC coatings at 3.5 weight percent of NaCl solution was explored using a Tafel polarisation plot. Microstructural studies were examined to investigate the electrochemical behaviour of the cold spray (CS) and FSPed MMC coatings. The results demonstrated that an enhancement in corrosion protection of the MMC deposits occurred at the 1st and 2nd runs of FSP, with superior corrosion performance observed at the 2nd run of FSP. The enhanced surface state is the primary enhancement mechanism of the electrochemical properties of the FSPed MMC coatings. For the higher run of FSP (3rd run), the electrochemical performance of the specimens was lower owing to the amalgamate action of the enhanced surface state with the aggravated interface of interior deposits.

Designing Advanced Biomedical Biodegradable Mg Alloys: A Review

The increased demand for alloys that can serve as implantation devices with outstanding bio-properties has led to the development of numerous biomedical Mg-based alloys. These alloys have been extensively investigated for their performance in living tissue with mixed results. Hence, there are still major concerns regarding the use of magnesium alloys for such applications. Among the issues raised are elevated corrosion rates, hydrogen generation, and the maintenance of mechanical integrity for designated healing times. In addition, toxicity can arise from the addition of alloying elements that are intended to improve the mechanical integrity and corrosion resistance of Mg alloys. The current work reviews the recent advances in the development of Mg alloys for applications as bio-absorbable materials in living organic environments. In particular, it attempts to develop a roadmap of effective factors that can be utilized when designing Mg alloys. Among the factors reviewed are the effects of alloying additions and processing methods on the exhibited mechanical properties and corrosion rates in simulated bio-fluids used in biomedical applications.

Enhanced Long-Term Corrosion Resistance of Mg Alloys by Superhydrophobic and Self-Healing Composite Coating

Enhanced Long-Term Corrosion Resistance of Mg Alloys by Superhydrophobic and Self-Healing Composite Coating

Facile fabrication of graphene oxide and MOF-based superhydrophobic dual-layer coatings for enhanced corrosion protection on magnesium alloy

Corrosion is an inevitable and thorny problem when magnesium (Mg) alloys are used in marine environments. Superhydrophobic coatings have great potential for metal corrosion protection due to their superhydrophobicity and self-cleaning properties. However, the poor mechanical stability of the surface seriously hinders the practical application. Herein, a robust superhydrophobic graphene oxide (GO)/polypyrrole (PPy)-zeolitic imidazolate framework-8 (ZIF-8) dual-layer coating was prepared on the surface of magnesium (Mg) alloy by electrodeposition and spraying method, which was composed of a bottom GO layer and a upper superhydrophobic PPy/ZIF-8 layer. The GO layer extends the transmission path of corrosion ions and the superhydrophobic coating prevents the contact between the Mg alloy and the corrosive solution. In addition, the dual-layer superhydrophobic coating has excellent self-cleaning and mechanical properties. More importantly, the as-prepared coating can withstand 3.5 wt% NaCl solutions for 120 h and still maintain good corrosion resistance. Furthermore, the GO layer and the superhydrophobic layer have a synergistic effect, which significantly improves the corrosion resistance of Mg alloys. The facile method and superhydrophobic dual-layer coatings will have good application prospects on a variety of metal substrates.