Corrosion Behavior Of Mg Research Articles

An insight investigation on mechanical and corrosion behavior of ultrasonic squeeze casting processed Mg based alloy composites for bio-implantation

Magnesium (Mg) alloys are gaining prominence in the bio-implantation process due to their low weight, high strength, greater compatibility and ease of biological degradability. However, poor strength and rapid degradation in the physiological environment inhibit their application as implant material. The present experimental investigation examines the effect of Zirconium oxide (ZrO2) reinforcement on mechanical and corrosion behaviors of Mg - Tin (Sn) alloy composites, for assessing their feasibility in the targeted field. Mg-5%ZrO2, Mg-1%Sn, and Mg-1%Sn/5 % ZrO2 were fabricated via ultrasonic aided squeeze casting (UASC) process. Characterization studies on the synthesized composites were carried out to evaluate their morphology using SEM with EDAX and XRD. Mechanical properties were evaluated using micro-hardness and compression tests. Furthermore, the corrosion behavior was determined using Tafel and electrochemical impedance spectroscopy (EIS). The results revealed that the Mg alloy bio-composite (Mg-1%Sn/5 % ZrO2) exhibits better compression (291.2 MPa) and yield (215.3 MPa) strength, elastic modulus (55.7 GPa), hardness (941.4 MPa) and reduced corrosion rate (0.475 mm/yr) than the base Mg and non-reinforced Mg bio-composite (Mg-1% Sn). Overall, the newly synthesized ZrO2 reinforced Mg bio-composite would potentially be used as a bio-implantation supportive material in bone fracture related treatments.

Corrosion behavior of Mg–Bi–Ca alloys prepared via high vacuum melting as biodegradable materials in Hank solution

The study investigated the corrosion behavior of Mg–Bi–Ca alloys in a balanced Hank solution through potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Corrosion potential (Ecorr), Current density (Icorr), Corrosion rate (CR), Impedance modulus (|Z|) and phase angle parameters were employed to analize the electrochemical test results. The effects of the quantity and distribution of the different phases, as well the percentage of Bi in the alloys, were assessed. The cell compatibility results indicated that both alloys are suitable for use as biodegradable implants, and the electrochemical testing results demonstrated that the primary corrosion mechanism observed in the alloys is continuous anodic dissolution, meaning the material steadily dissolves without forming a protective passivation layer. The behavior of impedance modulus and phase angle, which are indicators of the material's resistance to corrosión, were influenced by the reactions occurring at the material-electrolyte interface and the types of corrosion products formed. Additionally, the content of Bi in the alloys plays a role in determining these behaviors, particularly the eutectic phase. According to the CR criteria, the as-received Mg–4 %Bi–1 %Ca alloy in Hank solution at 37 °C is the most suitable for the fabrication of biodegradable implants.

Hot corrosion behavior of Mg\(_{2}\)SiO\(_{4}\) ceramic exposed to molten Na\(_{2}\)SO\(_{4}\) at 900℃ to 1100℃

Thermal barriers are used as protective coating for critical components working at high temperature of gas turbines. Forsterite (Mg2SiO4) ceramic is proposed by researchers as a novel thermal barrier coating (TBC), due to its low thermal conductivity and good thermal expansion. Hot corrosion results from the molten salts effect on the TBC’s surface, accumulated during the combustion processes. In this study, Mg2SiO4 samples were exposed to Na2SO4 molten salt at 900℃, 1000℃ and 1100℃ for 6 h in air. Samples were investigated and compared using scanning electron microscope (SEM) and X-Ray diffractometer (XRD). MgSO4 was the predominant corrosion product observed on the surface of the samples. Na2Mg5Si12O30 was also observed at 1000℃ and 1100℃, and Na2SiO3 appeared only on sample treated at 900℃.

Effect of Mn Addition and Heat Treatment on the Corrosion Behaviour of Mg–Ag–Mn Alloy

Effect of Mn Addition and Heat Treatment on the Corrosion Behaviour of Mg–Ag–Mn Alloy

Investigations of Electrochemical Characteristics of Mg-Al-Ca Alloys

Magnesium alloys possess a high strength-to-density ratio, thereby increasingly being utilized as lightweight structural materials in a range of industrial applications. Nevertheless, to compete with established materials like aluminum alloys, it is essential to understand the corrosion behavior of Mg and its alloys, as their high reactivity hampers industrial application. The addition of Ca to wrought Mg-Al alloys has gained attention for its ability to improve mechanical properties while also enhancing processing behavior. However, the wide range of alloy compositions within the class of Mg-Al-Ca alloys results in a variety of different corrosion properties. Consequently, this study contributes by investigating the corrosion behavior of two Mg-Al-Ca alloys, highlighting the influence of chemical composition and microstructure.

Corrosion inhibition induced by captopril in Hanks’ solution on bioresorbable Mg–Zn-(Y, Nd) alloys fabricated by powder metallurgical technology

Mg–Zn alloys containing rare-earth elements (REEs) have been regarded as potential candidates for bioresorbable stent materials. As implanted in coronary arteries, stents could be exposed to angiotensin-converting enzyme (ACE) inhibitor drugs that are widely used for post-percutaneous coronary intervention patient therapy. This work investigates the inhibitory effect of an ACE inhibitor drug, namely captopril, on the corrosion behavior of Mg–Zn-(Y, Nd) alloys in Hanks' solution. Three alloy compositions, namely Mg–1Zn-2.9Y, Mg–5Zn-1Nd, and Mg–2Zn-0.2Y-0.5Nd, were prepared by a powder metallurgical (PM) method. The corrosion behavior and inhibition efficiency were studied using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and a hydrogen evolution test. It is shown that captopril suppressed the dissolution kinetics of Mg–Zn-(Y, Nd) alloys in Hanks' solution. The captopril inhibition efficiencies (η) for the alloys are in the order of Mg–2Zn-0.2Y-0.5Nd > Mg–5Zn-1Nd > Mg–1Zn-2.9Y. A remarkable η of 48.4 % has been achieved for the Mg–2Zn-0.2Y-0.5Nd alloy. The EIS results revealed that the polarization resistance increased in the alloys after the addition of captopril to Hanks' solution. The Mott-Schottky analysis showed that the Mg–Zn-(Y, Nd) alloys behaved as an n-type semiconductor but switched to a p-type for the Mg–1Zn-2.9Y alloy in the captopril-containing Hanks’ solution. The surface analysis of the post-corrosion-tested sample has observed captopril film partially covering the α-Mg matrix, which acted as a protective layer against corrosion.

E-waste CRT panel glass reinforced magnesium composite processed through powder metallurgy: fabrication and mechanical performance evaluation

Cathode Ray Tube (CRT) panel glass with higher silica content has a potential to be used as reinforcement material in magnesium matrix composites. The present study aims to formulate a wear resistant magnesium hybrid composite by reinforcing silica rich E-waste CRT panel glass powder (0, 10 and 20 wt. %) and boron nitride (0, 2 and 4 wt. %) solid lubricant processed through powder metallurgy route. Composition of the CRT panel glass powder is identified through EDS and XRD analysis is performed for both base material and reinforcements. The developed green MMC shows increased hardness (∼53 %), porosity (∼7 %) and density (∼7 %) with respect to addition of CRT reinforcement. Porosity of hybrid composite increased vastly to 9.2 % when the CRT and BN content are increased to 20 % and 4 % respectively. A slight increment in (10 %) hardness is observed for 2 % addition of BN with Mg and Mg/CRT composite whereas hardness of the Mg and Mg/CRT MMC decreases with further addition of BN. The wear resistance of the composite enhanced with raise in CRT and BN content whereas the co efficient of friction decreases with increases in BN percentage. Corrosion behaviour of Mg is also analysed and found enhanced with reinforcement addition. It is identified from the results that the addition of CRT% up to 10 % yields significant results whereas further increase in CRT % to 20 provides only minor enhancements in properties. Further, it is suggested to restrict the addition of BN to 2 %.

Preparation and corrosion behavior of Mg(Li)-M layered double hydroxides films on the surface of magnesium-lithium alloy

Different Mg(Li)-M (M: Al, Fe, Cr) layered double hydroxides (LDHs) films were successfully prepared on Mg-Li alloy with in-situ growth method. Further, the corrosion inhibitor was screened and the tartaric acid-loaded LDHs (Mg(Li)-M LDHs-TA) films were prepared. The morphologies, compositions, structures and corrosion resistance of the LDHs films changed before and after tartaric acid loading. The Mg(Li)-Cr LDHs-TA film exhibits the most excellent corrosion resistance with a current density icorr 1.5 × 10–9 A cm–2. Moreover, corrosion mechanisms of the Mg(Li)-M LDHs and Mg(Li)-M LDHs-TA films were discussed in combination with Scanning Vibrating Electrode Technique.

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.

Discharge and corrosion behavior of Mg–2Zn–Mn–xY alloys as the anode for Mg-air battery

Discharge and corrosion behavior of Mg–2Zn–Mn–xY alloys as the anode for Mg-air battery

Effect of minor Gd addition on microstructure, mechanical performance, and corrosion behavior of Mg–Y–Gd alloys

Effects of minor Gd addition on the micro-structure, mechanical performance, and corrosion behavior of Mg-1Y alloys were systematically studied. With the addition of increased Gd content, the hydrogen evolution rate of Mg-Y-Gd alloys decreased from 2.0 to 0.5 mm/y. Moreover, the alloying Gd in Mg-Y-Gd alloys leaded to the transformation of the active Mg24Y5 phase into the Mg5(GdY) phase. The high corrosion resistance of Mg-1Y-0.6Gd alloy can be attributed to the fine grain size, uniform distribution of surface potential, and the formation of protective corrosion passivation film rich in Gd2O3 and Y2O3.

The inhibition effect of etidronate on degradation behavior of Mg–Zn–Y-Nd-Zr alloy

The control of corrosion behavior of Mg alloys for biomedical applications is a research hotspot in the field of biodegradable metallic implant materials. In recent years, the employment of corrosion inhibitors for regulating the corrosion behavior of Mg alloys has attracted attention. In this work, a promising corrosion inhibitor for Mg alloys, Etidronate (ETN), was selected from the drugs for the treatment of osteoporosis, and its effect on the corrosion behavior of Mg–Zn–Y-Nd-Zr (ZE21C Mg alloy) in simulated body fluids was systematically studied. The results show that ETN not only reduces the corrosion rate of the alloy, but also significantly weakens its tendency of localized corrosion, which is beneficial for improving the service reliability of Mg alloy for orthopedic application. This study provides an idea for corrosion control of biodegradable Mg alloys and is of great significance for promoting their development and applications.

Insight of the role of cooling method and soil environment on the corrosion behavior of Mg–2Nd alloys

Understanding the corrosion behavior of Mg alloys in the soil environments is crucial to preventing catastrophic accidents in their facilities due to the soil corrosion. The Mg–2Nd alloys were exposed to the soil after cooling in different ways under the same heat treatment conditions. The corrosion mechanisms of Mg–2Nd alloy in the soil are mainly affected by corrosion micro-batteries and macro-batteries. The more precipitates, the more severe micro-galvanic corrosion are formed. Meanwhile, the corrosion product films are damaged by micro-galvanic corrosion, which have a serious impact on the differential concentration of oxygen and differential infiltration of rainwater corrosion. The Mg–2Nd alloy buried in the soil with high water content and low oxygen permeability in corrosive macro-batteries will be corroded into anodes, thereby accelerating the corrosion rate of Mg–2Nd alloy in this part. Furthermore, the formation of corrosion product MgCO3 reduces the electrochemical activity of the sample surface, thereby reducing the corrosion rate of Mg–2Nd alloy in the soil. Therefore, the Mg–2Nd alloy after water-cooling has the best corrosion behavior in the soil environment.

Corrosion behaviors of Mg−39Pb−11.5Al−1B−0.4Sc alloy in 3.5 wt.% NaX (X=F, Cl, Br and I) solutions

Mg−39Pb−11.5Al−1B−0.4Sc alloy was prepared by melting method, and the corrosion behaviors and mechanisms in 3.5 wt.% NaX (X = F, Cl, Br, and I) solutions were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), polarization curve test, and electrochemical impedance spectroscopy (EIS). The results show that the phases of Mg−39Pb−11.5Al−1B alloy are α-Mg, Mg2Pb, Mg17Al12 and AlB2. The addition of Sc can refine the microstructure significantly. The corrosion resistance of Mg−39Pb−11.5Al−1B−0.4Sc alloy in NaX solutions is in the order of NaCl < NaBr < NaI < NaF. During the corrosion process in NaX (X=Cl, Br, and I) solutions, Mg is first dissolved, then Mg2Pb is dissolved, and finally Mg17Al12 is fallen off from matrix. The corrosion products of Mg and Mg2Pb are Mg(OH)2 and MgO, respectively.

Microstructure evolution and corrosion properties of ECAPed Mg–Pb-9.2Al-0.8B alloys

Effect of grain refinement on corrosion behavior of Mg–Pb-9.2Al-0.8B alloy by equal-channel angular pressing (ECAP). By measuring open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS), the corrosion behavior of as-cast and ECAP samples in 3.5 wt % NaCl solution were compared and analyzed. The results showed that sample obtained fine crystal after ECAP, and grain refining reduced the corrosion resistance of the alloy. In the polarization test, the Icorr value was the largest, and the type changed from local corrosion to uniform corrosion. Two factors weaken the corrosion resistance: The first is that β-Mg17Al12 phase is homogenized by the tissue and disappears, thus losing the barrier of corrosion propagation, resulting in reduced corrosion resistance. The second is that Mg + Pb eutectic phase produced by thermal deformation is the first to be corroded. As a result, the corrosion resistance of the alloy decreases after ECAP.

Development of sustainable novel Mg-Ca-Sc alloys with exceptional corrosion resistance

Mg-based alloys have been widely researched for biomaterial and structural applications as they fulfill several prerequisites, such as lightweight, high specific strength, and good biocompatibility, which are highly desirable. However, a long-standing obstacle to the widespread use of magnesium is its low corrosion resistance and increased cost upon increasing alloying content to enhance corrosion resistance. In this study, we report the effect of the simultaneous addition of rare-earth element (Sc) and non-rare earth element (Ca) maintaining low alloying content (∼ 1 wt%) on the mechanical, tribological, and corrosion behavior of Mg. The novel as-cast Mg-0.6Ca-0.5Sc alloy exhibited excellent corrosion resistance with a corrosion rate ∼ 40 % lower than the conventional as-cast WE43 alloy and ∼ 88 % lower than AZ31 alloy. A finer grain size and strong basal texture were achieved through thermomechanical processing, further enhancing the corrosion resistance of the as-cast novel alloys by ∼ 45 %. Stress corrosion cracking and wear testing in physiological saline solution were also conducted to study the combined effect of stress and corrosive electrolyte. The tensile and compression behavior remained practically the same upon adding Sc. However, the addition of 0.5 wt% Sc reduced the yield asymmetry by ∼ 10 % in as-cast and ∼ 5 % in recrystallized conditions. Furthermore, Mg-0.6Ca-0.5Sc alloy exhibited significant strength (∼ 175 %) and ductility (∼ 67 %) improvement under tensile testing in a physiological saline solution environment compared to Mg-0.6Ca alloy. The developed novel Mg-0.6Ca-0.5Sc ternary alloy exhibited enhanced resistance to corrosion, stress corrosion cracking, and wear relative to the Mg-0.6Ca binary alloy.

Initial micro-galvanic corrosion behavior between Mg2Ca and α-Mg via quasi-in situ SEM approach and first-principles calculation

Abstract The initial micro-galvanic corrosion behavior of Mg‒30wt%Ca alloy only containing Mg2Ca and α-Mg was studied by immersion testing in a 0.9% NaCl solution at 37oC. The quasi-in situ SEM and TEM results show that Mg2Ca corroded easier than α-Mg, indicating that Mg2Ca acted as an anode. The work function (Φ) for Mg2Ca calculated by first-principles is significantly lower compared to that for α-Mg. The Volta potential measured by a scanning Kelvin probe force microscope reveals that the Mg2Ca had a relatively low Volta potential (ψ) value. The lower Φ and ψ values for Mg2Ca indicate a lower electrochemical nobility, which is consistent with the experimental phenomenon.

Bio-inhibitive effect of an algal symbiotic bacterium on corrosion of magnesium in marine environment

It is a longstanding and challenging task to develop sustainable environment-friendly and cost-effective corrosion-protection technologies for Mg alloys, especially under marine conditions in which corrosion can normally be significantly accelerated by bacterial activity. However, this paper reports on the corrosion of highly active Mg interestingly inhibited by an algal-symbiotic bacterium Bacillus altitudinis. The corrosion of Mg in the presence of the bacterium drastically reduced by one order of magnitude after 14 days of immersion. This means that the algal-symbiotic bacterium widely available in natural ocean environments may be employed as a green and sustainable inhibitor in the marine industry. Based on electrochemical measurements, surface analyses and microbe experiments, a combined inhibition mechanism is proposed in the paper to interpret the interesting corrosion behavior of Mg.

Effects of MgO nano particles on the mechanical properties and corrosion behavior of Mg–Zn–Ca alloy

An as-extruded Mg–3Zn-0.2Ca-0.3MgO (wt.%, ZX0.3) composite with good mechanical properties and high corrosion resistance was designed and fabricated by hot extrusion based on the requirements of biodegradable Mg alloys. The results revealed that the average grain size was reduced about 50% to 1.9 μm and the yield stress was increased about 34%–269 MPa after adding MgO to Mg–3Zn-0.2Ca (wt.%, ZX) alloy. Theoretical calculation and experimental results showed that the grain boundary strengthening and Orowan strengthening were the main strengthening mechanisms (>95%) of the composite, while the addition of MgO NPs and the increasing of basal texture were harmful to the plastic of ZX0.3 composite. However, the activation of prismatic <a> dislocations and pyramidal <c> dislocations would reduce the negative impact of them. The corrosion test results revealed that in ZX0.3 composite, MgO nanoparticles (NPs) not only promoted the formation of the Mg(OH)2 layer, but also effectively barricaded the cracks extension in corrosion products layer, making the corrosion product layer much denser and durable. The corrosion rate of ZX0.3 composite was reduced by 30% to 0.79 mm/yr compared with that of ZX alloy. In addition, the reduced corrosion rate of matrix could provide a more suitable environment for cell adhesion and differentiation, which results in better cytocompatibility of the ZX0.3 compared with ZX alloy.

Probing Mg anode interfacial and corrosion properties using an organic/inorganic hybrid electrolyte

The high self-corrosion rate of Mg in aqueous electrolyte generates H2, which is the main impediment to restrict the utilization of Mg-air batteries. However, organic/inorganic hybrid electrolyte is prone to reduce the Mg degradation. Herein, the effect of different ethanol fractions in water with 0.6 M NaCl on corrosion behavior of Mg and battery discharge performances is demonstrated. The significant corrosion inhibition in a high content of ethanol (≥20 vol%) in electrolyte is attributed to the formation of a thinner, more corrosion protective layer enriched in magnesium oxide as demonstrated by scanning electron microscopy, X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Contrarily, in water-based electrolyte a thick, porous and rough layer principally composed of magnesium hydroxide is formed. By varying the ethanol to water fraction in the electrolyte in full battery cell, it is shown that even a small ethanol content (≤ 5 vol%), can greatly enhance the electrochemical performances of Mg anode. Within several ethanol content, 0.5 vol% demonstrates the best performances with a limited corrosion rate and greatly improves the discharge performance and the battery lifetime. It is demonstrated here that application of inorganic/organic dual electrolyte is a promising and easy way towards a well-controlled Mg anode reactivity and improved performances of Mg-air battery.