Corrosion Resistance Of Magnesium Alloy Research Articles

Investigation of Mechanical and Corrosion Properties of New Mg-Zn-Ga Amorphous Alloys for Biomedical Applications.

Magnesium alloys are considered as promising materials for use as biodegradable implants due to their biocompatibility and similarity to human bone properties. However, their high corrosion rate in bodily fluids limits their use. To address this issue, amorphization can be used to inhibit microgalvanic corrosion and increase corrosion resistance. The Mg-Zn-Ga metallic glass system was investigated in this study, which shows potential for improving the corrosion resistance of magnesium alloys for biodegradable implants. According to clinical tests, it has been demonstrated that Ga ions are effective in the regeneration of bone tissue. The microstructure, phase composition, and phase transition temperatures of sixteen Mg-Zn-Ga alloys were analyzed. In addition, a liquidus projection of the Mg-Zn-Ga system was constructed and validated through the thermodynamic calculations based on the CALPHAD-type database. Furthermore, amorphous ribbons were prepared by rapid solidification of the melt for prospective alloys. XRD and DSC analysis indicate that the alloys with the most potential possess an amorphous structure. The ribbons exhibit an ultimate tensile strength of up to 524 MPa and a low corrosion rate of 0.1-0.3 mm/year in Hanks' solution. Therefore, it appears that Mg-Zn-Ga metallic glass alloys could be suitable for biodegradable applications.

Recent Progress on Atmospheric Corrosion of Field-Exposed Magnesium Alloys

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.

Constructing sodium alginate/carboxymethyl chitosan coating capable of catalytically releasing NO or CO for improving the hemocompatibility and endothelialization of magnesium alloys

Although significant progress in developing biodegradable magnesium alloy materials in cardiovascular stents has been achieved recently, they still face challenges such as rapid in vivo corrosion degradation, inferior blood compatibility, and limited re-endothelialization after the implantation. Hydrogel coating that can catalyze the liberation of gas signal molecules offers a good solution to alleviate the corrosion rate and enhance the biocompatibility of magnesium and its alloys. In this study, based on alkaline heat treatment and construction of polydopamine coating on the surface of magnesium alloy, sodium alginate/carboxymethyl chitosan (SA/CMCS) gel was simultaneously covalently grafted onto the surface to build a natural polymer hydrogel coating, and selenocystamine (SeCA) and CO release molecules (CORM-401) were respectively immobilized on the surface of the hydrogel coating to ameliorate the anticoagulant performance and accelerate endothelial cells (ECs) growth by catalyzing the release of endogenous gas signal molecules (NO or CO). The findings verified that the as-prepared hydrogel coating can catalyze the liberation of CO or NO and significantly improve the corrosion resistance of magnesium alloy. At the same time, owing to the excellent hydrophilicity of the hydrogel coating, the good anticoagulant property of sodium alginate, and the ability of CMCS to promote the ECs growth, the modified magnesium alloy could significantly improve the albumin adsorption while preventing the adsorption of fibrinogen, hence significantly augmenting the anticoagulant properties and promoting the ECs growth. Under the catalytic release of NO or CO, the released gas molecules further enhanced hemocompatibility and promoted endothelial cell (EC) growth and the expression of vascular endothelial growth factor (VEGF) and NO of ECs. Therefore, the bioactive coatings that can catalyze the release of NO or CO have potential applications in constructing surface bioactive coatings for magnesium alloy materials used for intravascular stents.

Corrosion-resistant superhydrophobic composite coating with mechanochemical durability

It is important to improve the corrosion resistance of magnesium alloy for expanding its application field. Poor durability seriously restricts the practical application of superhydrophobic anti-corrosion coatings. Here, a durable superhydrophobic anti-corrosion coating was prepared on AZ31 Mg substrate via a facile one-step spraying approach. The microscale glass fibers (GF) and nanoscale hydrophobic SiO2 particles were integrated into the epoxy resin (ER) to construct superhydrophobic composite coating (ER/GF-SiO2). Benefitting from the air cushion and physical barrier effect of superhydrophobic coating, the ER/GF-SiO2 coating exhibits good reinforced protectives properties. Compared with the AZ31, the corrosion current density of superhydrophobic coating decreased by three orders of magnitude and the low-frequency impedance modulus decreased by one order of magnitude. The ER/GF-SiO2 coating still maintained a high protective efficiency (89.44 %) after immersion in 3.5 wt% NaCl solutions for 13 d. The ER/GF-SiO2 coating shown good mechanochemical durability. The superhydrophobicity can be maintained after 40 m of sandpaper abrasion, 30 min of water impact, 20 min of sand impact, and 80 cycles tape-peeling. Furthermore, the high bond strength of the coating-substrate was verified by energetic analysis of molecular dynamics simulation at a microscopic level. The facile and effective preparation process provides an effective strategy for large-scale industrial production of durable superhydrophobic coating.

Corrosion resistance of magnesium alloy surfaces substantially upgraded by gradient energy irradiation of femtosecond lasers

The poor corrosion resistance of magnesium (Mg) alloys is known to constitute a major obstacle to their practical applications. In this work, we proposed an approach of femtosecond laser multi-grid-scanning with the gradual decreasing energy fluence, to modulate the surface oxide properties for the anti-corrosion performance enhancement. This kind of laser processing can significantly increase the oxide passivation layer thickness by more than 100 times compared with the bare sample, and improve the oxygen content on the material surface to as high as 55.87 %. Simultaneously, the available size of MgO nanograins is further refined and has more spatially uniform distribution. Moreover, the massive production of micro/nano-structures by the femtosecond laser irradiation tends to promote the surface into the superhydrophobic with a contact angle of CA=162 ± 2 ° and a slide angle of SA=1.5 ± 0.5 °. As a result, the obtained optimal values for the corrosion current density and the annual corrosion rate are reduced to Icorr = 0.5 μA/cm2 and CR = 7×10−3 mm/y, respectively, more than 2 orders of magnitude lower than the bare sample. Such a method provides an efficient strategy to enhance the corrosion resistance of metal surfaces for future applications.

Dissolution and diffusion behavior of solid Mn in Mg melt

Mn is an important alloying element that can improve the mechanical properties and corrosion resistance of magnesium alloys and it belongs to the peritectic reaction type element in Mg melt. In this study, an Mn/Mg solid–liquid diffusion couple was designed to investigate the diffusion behavior of solid Mn in Mg melt at 1023 ∼ 1073 K. The dissolution behavior of Mn in Mg is dominated by Mg elements entering Mn crystal lattice from the original Mn/Mg interface. After 2 h diffusion, the Mn concentration gradient occurs between the new solid–liquid interface and the original Mn/Mg interface, and the concentration of Mn outside the original Mn/Mg interface remains about 2 wt%. For Mn/Mg solid–liquid diffusion at 1023 K∼1073 K for 2 h, the interdiffusion coefficient is in the range from 0.1 × 10-12 to 0.8 × 10-12m2/s.

Effect of Gadolinium Content on the Microstructures and Corrosion Properties of Mg-4Zn-3Gd Alloy

Lightweight metallic alloys in the transport sector are the essential choice to reduce carbon monoxide emissions. Magnesium (Mg) can serve this purpose appreciably because it has a low density compared to other metallic metals and a high strength in a small portion of metals. The reason behind this is having very low weight. Notwithstanding the alloys exhibit high susceptibility to corrosion especially galvanic corrosion, which impedes it from its various applications. The corrosion resistance of magnesium alloy depends largely on the surface film whether it can protect well and the corrosion due to galvanic effect between the second phase particles or microstructures and the magnesium matrix. Role of second phase particles eventually improves the corrosion property by enhancing its resistance to corrosion. Mg-4Zn being a promising alloy, 3 wt% Gd has been added further to investigate the corrosion resistant properties of Mg-4Zn-3Gd alloy. After preparing the alloys by casting method in induction furnace followed by homogenization at 410°C, the sample was hot rolled at 400°C. Preparation of the samples has been verified by EDS, XRF and XRD analysis. Corrosion study has been done for 1 hour, 24 hours and 72 hours. Microstructures have been taken for as cast, homogenized, and as rolled condition before corrosion test. The analysis shows a large difference in the grain size and phase distribution. Due to dynamic recrystallization during rolling hardness also shows differences compared to as cast and homogenized sample. The corrosion test is performed by weight loss test, electrochemical measurement, and immersion test. In the results, it has been seen an increase in corrosion rate at the initial stage, however it came to a constant rate after some time. After corrosion test, optical micrographs (OM) and scanning electron microstructures (SEM) images show typical morphology of corroded surface with some micro cracks. The presence of Gd in Mg-4Zn alloy enhanced the corrosion performance when it is done for longer time.

Corrosion resistance of a superhydrophobic polypropylene coating on magnesium alloy AZ31

PurposeTo 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/approachSiO2 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.FindingsHydrophilic 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/valueThe composite coating effectively and durably enhances the corrosion resistance of magnesium alloys.

Application and Perspectives: Magnesium Materials in Bone Regeneration.

The field of bone regeneration has always been a hot and difficult research area, and there is no perfect strategy at present. As a new type of biodegradable material, magnesium alloys have excellent mechanical properties and bone promoting ability. Compared with other inert metals, magnesium alloys have significant advantages and broad application prospects in the field of bone regeneration. By searching the official Web sites and databases of various funds, this paper summarizes the research status of magnesium composites in the field of bone regeneration and introduces the latest scientific research achievements and clinical transformations of scholars in various countries and regions, such as improving the corrosion resistance of magnesium alloys by adding coatings. Finally, this paper points out the current problems and challenges, aiming to provide ideas and help for the development of new strategies for the treatment of bone defects and fractures.

Optimization of anodizing conditions and hole sealing treatments for enhanced anti-corrosion properties of magnesium alloys

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.

Comparative study of CaO and CaCO3 on microstructure refinement, mechanical and corrosion resistance of AM60 alloy

Grain refinement is a crucial technique for enhancing the mechanical properties and corrosion resistance of magnesium alloys. In this study, the addition of 0.3 wt% CaO and 0.3 wt% CaCO3 successfully refined the AM60 alloy, resulting in a significant reduction in the average grain size from 326 μm to 96 μm (when adding CaCO3). The refined grain size of the as-cast AM60 alloy led to an increase in both tensile strength and yield strength to 118.2 MPa and 72.6 MPa, representing a respective increase of 35% and 23% compared to the alloy without the refiner. As results of EBSD, it is verified that the basal slip system (0001)<112‾0> has a higher Schmid factor after adding CaO, which indicates that this system has higher activity. The substitution reaction between CaO and Mg can produce synergistic effects from the solute effect of Ca and the nucleating effect of residual CaO, which play an important role in grain refinement. Due to the fine grain size and diffuse distribution of the second phase in the AM60-CaCO3 alloy and the thermal decomposition of CaCO3, which consumes the aluminum element in the matrix, the content of the β-phase (Mg17Al12) is reduced. Consequently, this reduces the electric coupling effect between the β-phase and the magnesium matrix. The AM60-CaCO3 alloy exhibited the most superior corrosion resistance, achieving a corrosion rate of only 1.01 mm y−1, representing a 48.9% reduction in corrosion rate compared to the AM60 alloy.

Enhancing wear and corrosion resistance of magnesium alloys through in-situ Al2O3 doping for plasma electrolytic oxidation coating

The surface of PEO coatings may contain micro-cracks and pores, which can facilitate the penetration of corrosive media and initiate corrosion. Doping particles has been identified as an effective method for enhancing corrosion resistance. This study investigates the impact of in-situ doping of Al2O3 particles of varying sizes on the performance of PEO coatings. It was observed that at lower concentrations, the particles are primarily inertly doped into the coating, while larger particles tend to be deposited on the surface. The addition of Al2O3 particles through the PEO process improves breakdown and final voltages, reduces porosity, and enhances abrasion resistance of the coatings. Furthermore, the │Z│0.01 Hz of Al2O3-containing coatings remained at approximately 107 Ω⋅cm2 for 10 days during immersion in NaCl solution. The corrosion current density is reduced from 78.01 to 6.51 nA/cm2. Among the different coatings, the PEO- Al2O3-200 coating exhibited the most promising results in terms of corrosion resistance and lubricating properties. The enhanced corrosion resistance is attributed to the promotion of Mg2Al(OH)7 formation during the corrosion process.

Topological characterization of the microstructure of magnesium alloy materials based on complex networks

Abstract Magnesium alloys, as the lightest commercial metal engineering structural materials, have good application prospects in the automotive, communication equipment, aerospace, and military industries because of their light specific gravity, high strength properties such as specific strength and stiffness, shielding from electromagnetic radiation, and easy recycling. In this paper, starting from the density and microstructure of magnesium alloy, the mechanical properties and corrosion resistance of magnesium alloy are proposed to measure the indexes, and the corresponding prediction model is constructed. Then, fine-crystal magnesium alloys are prepared sequentially by ingot casting and isometric channel extrusion, and then the microstructure of magnesium alloys is observed by scanning electron microscope and transmission electron microscope to extract the micro-parameters of magnesium alloys. A martensitic phase transition topology model was introduced to determine the macroscopic shape strain of magnesium alloy crystals. Complex network analysis is used to quantify the topological structure parameters of a magnesium alloy network in terms of degree, clustering coefficient, and average path length. Finally, the correlation between the macroscopic features and microstructure of magnesium alloy is explored with the obtained data, and the mechanical and corrosion resistance properties of magnesium alloy are analyzed through simulation experiments by combining them with the constructed prediction model. The microstructural topological characteristic parameters of magnesium alloys show that when the pressure is 50 kPa, the average path length after weighting decreases from 36.012 × 10−3 to 34.015 × 10–3, and the force transfer efficiency is gradually increasing. The AZ31 alloy samples obtained from casting in this paper have a capacitive arc diameter of about 1600 Ω-cm² and the best corrosion resistance among the tested samples.

Effect of ECAP and volume ultrasonic treatment on the corrosion resistance of magnesium

Magnesium and its alloys are promising materials for manufacturing bioresorbable implants. Various combinations of thermo-mechanical processing are used to improve the mechanical properties and corrosion resistance of magnesium alloys, forming the necessary structural state, which, in turn, requires determining the influence of various structural factors (grains, grain boundaries, dislocations, second-phase particles, etc.) on the complex properties of 'strength - corrosion resistance'. In this study, an experiment was conducted to determine the influence of structural changes in pure magnesium on mechanical properties and corrosion resistance in a physiological environment after deformation using equal channel angular pressing (ECAP) and post-deformation ultrasonic treatment. It was found that ECAP and subsequent ultrasonic treatment lead to a twofold increase in the yield strength of magnesium from 30 to 60 MPa. The increase in microhardness after ECAP is 50 MPa, while ultrasonic treatment results in an increase in microhardness by 230 MPa. After deformation, corrosion resistance changes significantly: ECAP reduces the corrosion rate compared to the initial state of magnesium by approximately 7 times, to values of 7 mm/year. Subsequent volume ultrasonic treatment does not lead to significant changes in the corrosion rate, which in this case was 10 mm/year.

Enhancing the corrosion resistance of magnesium alloys with biodegradable poly(trimethylene carbonate) chemical modification coating

Magnesium (Mg) alloys have great potential as biodegradable materials for medical device. However, their susceptibility to corrosion poses a significant challenge for practical applications. In this study, the poly(trimethylene carbonate)-dimethacrylate (PTMC-dMA) was employed as a coating material for ZE21B magnesium alloys. Upon UV irradiation, the PTMC-dMA macromer undergoes cross-linking to form a uniform PTMC coating with a thickness of approximately 5 μm, effectively protecting the magnesium alloy. The corrosion resistance in simulated body fluid (SBF) was evaluated through immersion testing, which showed minimal hydrogen generation (0.16 mL/cm2) during the initial 24-h period and slight corrosion observed on the PTMC-coated magnesium alloy surface after continuous immersion for 21 days. The silane coupling agent significantly enhanced the adhesive performance between the polymer and alloy. Micro-scratch tests revealed adhesion forces of 3.79 N and 5.75 N for coatings without and with the silane agent, respectively. Electrochemical tests also demonstrated the efficacy of silane treatment, showing corrosion currents of 2.100 × 108 A/cm2 for silane-treated samples compared 6.263 × 107 A/cm2 for untreated ones. Given its exceptional tensile and protective properties, this coated material is ideal for intricate bioresorbable applications, like endovascular bioresorbable stents.

Machine Learning in Enhancing Corrosion Resistance of Magnesium Alloys: A Comprehensive Review

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.

Corrosion and wear resistant polyp-xylene composite coating on AZ31 magnesium alloy prepared by micro-arc oxidation and vapor deposition

To improve the wear and corrosion resistance of magnesium alloy, a multifunctional organic/inorganic hybrid coating was prepared on AZ31 magnesium alloy by microarc oxidation and vapor deposition of Polyp-xylene (MAO-PPX). Electrochemical tests show that the MAO-PPX composite coating can effectively block the corrosive medium and improve the corrosion resistance of magnesium alloy. Long-term corrosion protection was confirmed by neutral salt spray tests at 35 °C with 5 wt% NaCl. In addition, the MAO-PPX composite coating demonstrated a much lower friction coefficient which could be attributed to the polyp-xylene filled in the micropores of the MAO layer and transferred on the counterpart sphere. This composite coating with excellent anti-corrosion and decent lubricating properties has broad application prospects in surface protection of magnesium alloys.

Improved corrosion resistance of magnesium alloy prepared by selective laser melting through T4 heat treatment for biomedical applications

Selective laser melting (SLM) technology has broad prospects for developing magnesium alloys in structural and biomedical applications. The effects of T4 heat treatment on microstructure, mechanical properties and corrosion resistance of as-built AZ91D alloy were investigated. The results showed that after T4 treatment, β-Mg17Al12 phases distributed around the matrix changed from networks to diffuse dots and then disappeared at 420 °C for 1 h. The tensile strength and hardness of AZ91D alloy decreased after T4 treatment. In addition, electrochemical and immersion experiments showed that the corrosion resistance was greatly improved after solution. Compared with the as-built AZ91D alloy, the solution-treat sample exhibited higher corrosion resistance in Hanks' solution, and its corrosion current density was reduced by 70%, hydrogen evolution rate by 57%, and corrosion rate by about 78% in the weightless experiment. In this study, after solution-treat, the corrosion resistance of as-built AZ91D can be significantly improved while meeting the mechanical requirement of degradable alloys, and has great potential for biomedical applications.

Effect of minor Ca addition on microstructure and corrosion behavior of Mg–Y–Ca alloys

The poor corrosion resistance of magnesium and magnesium alloys limited their industry applications, especially attributed to the loose and porous corrosion product film. Moreover, it is of great importance to improve the corrosion resistance of magnesium alloy by economic and environmental protection methods. In this study, the Mg–Y–Ca alloys prepared by the addition of trace Ca and Y elements showed good corrosion resistance. In addition, the effects of minor Ca on the microstructure and corrosion behavior of Mg–1Y alloy were systematically studied. With the increase of Ca content, the corrosion resistance of Mg–1Y-xCa alloys (x = 0, 0.05, 0.1 and 0.2 wt%) was found to improve and then decrease. Among prepared Mg–1Y-xCa alloys, Mg–1Y-0.05Ca exhibited the lowest corrosion rate of 0.757 mm y−1. The high corrosion resistance of Mg–1Y-0.05Ca can be attributed to the fine grain size, and the formation of a protective corrosion passivation film rich in Y2O3, CaCO3 and (MgCa)CO3. However, the excessive addition of Ca element led to the decline of corrosion resistance, resulting from the mass generated Mg2Ca phase causing serious micro-galvanic corrosion, which destroyed the stability of the corrosion product film and damaged the corrosion protection.

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.