Comparison of the short and long-term degradation behaviors of as-cast pure Mg, AZ91 and WE43 alloys

Öcal, Ezgi Bütev; Esen, Ziya; Aydınol, Kadri; Dericioğlu, Arcan F.

doi:10.1016/j.matchemphys.2019.122350

Cited by 41 publications

(38 citation statements)

References 43 publications

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“…The course of the hydrogen evolution exhibits a reduction of the slope and suggests a passivating corrosion behavior of the alloy Mg WE43 (Figure 4). In general, the course is comparable to other studies that investigated Mg WE43 [9,11]. In a study by Jung et al, a qualitatively and quantitatively similar course was observed on the same alloy composition [10].…”

Section: Discussionsupporting

confidence: 88%

“…Besides the extensive homogeneous corrosion morphology, the samples of unaccelerated corrosion show locally intensified corrosion ( Figure 6). According to current literature, these are due to increased accumulations of the alloying elements yttrium and zirconium [11,33]. By measuring the Volta potential, Coy et al were able to detect significant differences between the zirconium-rich (about +170 mV) as well as the yttrium-rich precipitates (about +50 mV) and the α-Mg matrix, whereas the second phase and β-phase showed negligible differences (+25 and +15 mV, respectively) [30].…”

Section: Discussionmentioning

confidence: 99%

“…A distinction must be made between an in vitro corrosion rate, determined in a preclinical trial, and an in vivo corrosion rate, determined in an animal experiment. Since animal experiments are ethically questionable, many studies focus on in vitro corrosion investigations [9][10][11], which can be divided into electrochemical [12][13][14] and immersion investigations [15][16][17]. In the field of electrochemical testing, potentiodynamic polarization (PDP) measurement is often used due to the short test duration.…”

Section: Introductionmentioning

confidence: 99%

“…The current method to determine the in vitro corrosion rate and evaluate the corrosion behavior is the immersion test with detection of the hydrogen volume produced and or the mass loss [11,[15][16][17]. The corrosion rate can be determined immediately via the mass loss; however, it does not allow in situ measurements, and the removal of the corrosion layer by-e.g., the carcinogenic chromic acid-is another disadvantage.…”

Section: Introductionmentioning

confidence: 99%

“…The arising corrosion layer is porous and allows the electrolyte to access the surface. With increasing immersion time, a thicker, more protective corrosion layer is formed, leading to a decrease in accessibility and thus to a decrease in HER [11,22,23]. This effect can be enhanced by alloying elements that change the nature of the corrosion layer [24].…”

Section: Introductionmentioning

confidence: 99%

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Assessment of Galvanostatic Anodic Polarization to Accelerate the Corrosion of the Bioresorbable Magnesium Alloy WE43

Wegner

Walther

2021

Applied Sciences

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In the field of surgery, bioresorbable magnesium is considered a promising candidate. Its low corrosion resistance, which is disadvantageous for technical application, is advantageous for surgery since the implant fully degrades in the presence of the water-based body fluids, and after a defined time the regenerating bone takes over its function again. Therefore, knowledge of the corrosion behavior over several months is essential. For this reason, an in vitro short-time testing method is developed to accelerate the corrosion progress by galvanostatic anodic polarization without influencing the macroscopic corrosion morphology. The initial corrosion rate of the magnesium alloy WE43 is calculated by detection of the hydrogen volume produced in an immersion test. In a corresponding experimental setup, a galvanostatic anodic polarization is applied with a three-electrode system. The application range for the polarization is determined based on the corrosion current density from potentiodynamic polarization. To correlate the initial corrosion rate, and accelerated dissolution rate, the corrosion morphologies of both test strategies are characterized by microscopy images, as well as energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy. The results demonstrate that the dissolution rate can be increased in the order of decades with the limitation of a changed corrosion morphology with increasing polarization. With this approach, it is possible to characterize and exclude new unsuitable magnesium alloys in a time-efficient manner before they are used in subsequent preclinical studies.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Assessment of Galvanostatic Anodic Polarization to Accelerate the Corrosion of the Bioresorbable Magnesium Alloy WE43

Wegner

Walther

2021

Applied Sciences

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Enhanced corrosion resistance and reduced cytotoxicity of the AZ91 Mg alloy by plasma nitriding and a hierarchical structure composed of ciprofloxacin‐loaded polymeric multilayers and calcium phosphate coating

Shanaghi

Mehrjou

Chu

2021

J Biomedical Materials Res

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Much effort has made to lessen the cytotoxicity and enhance the corrosion resistance of biodegradable magnesium alloys, for example, by depositing multilayered polymeric coatings containing hydroxyapatite. In this work, a hierarchical structure composed of ciprofloxacin (Cip)‐loaded on polyacrylic acid (PAA) and poly (ethyleneimine) (PEI) as biocompatible polymeric multilayers and calcium phosphate coating as the top layer is formed by the sol–gel method on the AZ91 Mg alloy with an intermediate layer formed by nitrogen plasma immersion ion implantation. The thicknesses of the multilayered coating and nitrided layer (Mg3N2) are 10 μm and 140 nm, respectively. The corrosion current density decreases by 95.6% and the corrosion potential in the polarization curve shifts to the positive direction by 23%. The passivation process which occurs at defects by deposition of corrosion products mitigates both galvanic and localized corrosion. Slight increase in the contact angle and surface free energy, enhanced corrosion resistance, and reduced cytotoxicity are observed from the multilayered structure. The better corrosion resistance enables better control of release of Cip. Biological assessment indicates that the antibacterial activity against Escherichia coli is improved by 100% after culturing for 24 hr and the cell viability and noncytotoxic behavior of the coated AZ91 are enhanced as well. The corrosion behavior and biological results suggest that the strategy of using a hierarchical structure composed of Cip‐loaded polymeric multilayers in conjunction with an intermediate plasma nitrided layer has large potential in the development of biodegradable orthopedic implants made of Mg alloys.

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Biodegradable AZ91 magnesium alloy/sirolimus/poly D, L‐lactic‐co‐glycolic acid‐based substrate for cardiovascular device application

Mohanta,

Ramdhun,

Thirugnanam

et al. 2023

J Biomed Mater Res

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Biodegradable drug‐eluting stents (DESs) are gaining importance owing to their attractive features, such as complete drug release to the target site. Magnesium (Mg) alloys are promising materials for future biodegradable DESs. However, there are few explorations using biodegradable Mg for cardiovascular stent application. In this present study, sirolimus‐loaded poly D, L‐lactic‐co‐glycolic acid (PLGA)‐coated/ sirolimus‐fixed/AZ91 Mg alloy‐based substrate was developed via a layer‐by‐layer approach for cardiovascular stent application. The AZ91 Mg alloy was prepared through the squeeze casting technique. The casted AZ91 Mg alloy (Mg) was alkali‐treated to provide macroporous networks to hold the sirolimus and PLGA layers. The systematic characterization was investigated via electrochemical, optical, physicochemical, and in‐vitro biological characteristics. The presence of the Mg17Al12 phase in the Mg sample was found in the x‐ray diffraction system (XRD) spectrum which influences the corrosion behavior of the developed substrate. The alkali treatment increases the substrate's hydrophilicity which was confirmed through static contact angle measurement. The anti‐corrosion characteristic of casted‐AZ91 Mg alloy (Mg) was slightly less than the sirolimus‐loaded PLGA‐coated alkali‐treated AZ91 Mg alloy (Mg/Na/S/P) substrate. However, dissolution rates for both substrates were found to be controlled at cell culture conditions. Radiographic densities of AZ91 Mg alloy substrates (Mg, Mg/Na, and Mg/Na/S/P) were measured to be 0.795 ± 0.015, 0.742 ± 0.01, and 0.712 ± 0.017, respectively. The star‐shaped structure of 12% sirolimus/PLGA ensures the bioavailability of the drugs. Sirolimus release kinetic was fitted up to 80% with the “Higuchi model” for Mg samples, whereas Mg/Na/S/P showed 45% fitting with a zero‐order mechanism. The Mg/Na/S/P substrate showed a 70% antithrombotic effect compared to control. Further, alkali treatment enhances the antibacterial characteristic of AZ91 Mg alloy. Also, the alkali‐treated sirolimus‐loaded substrates (Mg/Na/S and Mg/Na/S/P) inhibit the valvular interstitial cell's growth significantly in in‐vitro. Hence, the results imply that sirolimus‐loaded PLGA‐coated AZ91 Mg alloy‐based substrate can be a potential candidate for cardiovascular stent application.

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Comparison of the short and long-term degradation behaviors of as-cast pure Mg, AZ91 and WE43 alloys

Cited by 41 publications

References 43 publications

Assessment of Galvanostatic Anodic Polarization to Accelerate the Corrosion of the Bioresorbable Magnesium Alloy WE43

Assessment of Galvanostatic Anodic Polarization to Accelerate the Corrosion of the Bioresorbable Magnesium Alloy WE43

Enhanced corrosion resistance and reduced cytotoxicity of the AZ91 Mg alloy by plasma nitriding and a hierarchical structure composed of ciprofloxacin‐loaded polymeric multilayers and calcium phosphate coating

Biodegradable AZ91 magnesium alloy/sirolimus/poly D, L‐lactic‐co‐glycolic acid‐based substrate for cardiovascular device application

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