Mechanical Characteristics of an Anodized Magnesium Alloy for Biodegradable Implants

2013 ◽  
Author(s):  
Leon White ◽  
Sudheer Neralla ◽  
Ruben Kotoka ◽  
Yongseok Jang ◽  
Yeoheung Yun ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Electrolyte Solution ◽  
Protective Coatings ◽  
Microstructural Characterization ◽  
Mg Alloys ◽  
Biodegradable Implants ◽  
Treatment Technique ◽  
Corrosion Properties ◽  
Biodegradable Implant ◽  
Beneficial Effects

In recent years, magnesium (Mg) alloys have emerged as possible biodegradable implant materials; however the degradation rate of Mg occurs at a higher rate than tolerable for the human body. Plasma electrolytic oxidation (PEO) has been used in the past as a useful surface treatment technique to improve the anti-corrosion properties of Mg alloys by forming protective coatings. This present work focuses on the effect of electrolyte solution on the corrosion, microstructural, and nanomechanical behavior of PEO coatings for possible use in biodegradable implants. The experimental parameters applied during PEO process did influence the structure, thickness, and morphology of the coating. Microstructural characterization of the coating was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) followed by image analysis and energy dispersive spectroscopy (EDX). Further, nanoindentation was employed to evaluate nanohardness and Young’s modulus of the PEO coating. The results show beneficial effects of the PEO coating to enhance the corrosion resistance of the uncoated AZ31 magnesium alloy. The XRD pattern shows that the components of the film vary based on electrolyte solution. The film composition does affect the nanomechanical behavior.

scholarly journals Enhancing the Mechanical Properties of Biodegradable Mg Alloys Processed by Warm HPT and Thermal Treatments

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6399
Author(s):  
Andrea Mizelli-Ojdanic ◽  
Jelena Horky ◽  
Bernhard Mingler ◽  
Mattia Fanetti ◽  
Sandra Gardonio ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermomechanical Processing ◽  
High Pressure Torsion ◽  
Heat Treatments ◽  
Mg Alloys ◽  
Processing Route ◽  
Corrosion Properties ◽  
Biodegradable Implant ◽  
Significant Strength ◽  
Low Temperature Processing

In this study, several biodegradable Mg alloys (Mg5Zn, Mg5Zn0.3Ca, Mg5Zn0.15Ca, and Mg5Zn0.15Ca0.15Zr, numbers in wt%) were investigated after thermomechanical processing via high-pressure torsion (HPT) at elevated temperature as well as after additional heat treatments. Indirect and direct analyses of microstructure revealed that the significant strength increases arise not only from dislocations and precipitates but also from vacancy agglomerates. By contrast with former low-temperature processing routes applied by the authors, a significant ductility was obtained because of temperature-induced dynamic recovery. The low initial values of Young’s modulus were not significantly affected by warm HPT-processing. nor by heat treatments afterwards. Also, corrosion resistance did not change or even increase during those treatments. Altogether, the study reveals a viable processing route for the optimization of Mg alloys to provide enhanced mechanical properties while leaving the corrosion properties unaffected, suggesting it for the use as biodegradable implant material.

scholarly journals Superplasticity at Intermediate Temperatures of ZK60 Magnesium Alloy Processed by Indirect Extrusion

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 606
Author(s):  
César Palacios-Trujillo ◽  
José Victoria-Hernández ◽  
David Hernández-Silva ◽  
Dietmar Letzig ◽  
Marco A. García-Bernal
Keyword(s):  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Deformation Mechanism ◽  
Extrusion Direction ◽  
Grain Boundary Sliding ◽  
Mg Alloys ◽  
Homogeneous Microstructure ◽  
Texture Measurement ◽  
Average Grain Size ◽  
Zk60 Magnesium Alloy

Magnesium alloys usually exhibit excellent superplasticity at high temperature. However, many Mg alloys have poor formation ability near room temperature. Therefore, preparation of Mg alloys with suitable microstructures to show low or intermediate temperature superplasticity is an important goal. In this work, the superplastic behavior at intermediate temperatures of a commercial ZK60 magnesium alloy processed by indirect extrusion was investigated. After extrusion, the alloy showed a refined and homogeneous microstructure with an average grain size of 4 ± 2 μm. Overall texture measurement indicated that the alloy showed a strong prismatic texture with the highest intensity oriented to pole ⟨101¯0⟩. A texture component ⟨1¯21¯1⟩ parallel to the extrusion direction was found; this type of texture is commonly observed in Mg alloys with rare earth additions. Tensile tests were performed at temperatures of 150, 200, and 250 °C at three strain rates of 10−2, 10−3, and 10−4 s−1. A very high ductility was found at 250 °C and 10−4 s−1, resulting in an elongation to failure of 464%. Based on calculations of the activation energy and on interpretation of the deformation mechanism map for magnesium alloys, it was concluded that grain boundary sliding (GBS) is the dominant deformation mechanism.

Mechanical properties and wear-corrosion resistance of a new compound extrusion process for magnesium alloy AZ61

2020 ◽  
Vol 62 (4) ◽  
pp. 395-399
Author(s):  
Jiehui Liu ◽  
Hongjun Hu ◽  
Yang Liu ◽  
Dingfei Zhang ◽  
Zhongwen Ou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Magnesium Alloy ◽  
Equal Channel Angular Extrusion ◽  
Extrusion Process ◽  
Corrosion And Wear ◽  
Nacl Solution ◽  
Corrosion Properties ◽  
Manufacturing Method ◽  
Az61 Magnesium Alloy

Abstract Compound extrusion (CE) is a newly developed plastic deformation technique which combines direct extrusion (DE) with a two-pass equal channel angular extrusion (ECAE). This paper focuses on the strength, ductility and anti-corrosion properties of an NaCl solution at certain concentrations and the wear-resistance of dry sliding AZ61 magnesium alloy prepared by CE and DE. It is found that the strength and elongation of the AZ61 alloy prepared by CE are enhanced because of grain refinement. Furthermore, AZ61 magnesium alloy made by CE displays higher corrosion and wear resistance than that prepared by DE. Experimental results prove that CE is a prospective manufacturing method for improving the mechanical properties, anti-corrosion and anti-wear of AZ61 magnesium alloy.

scholarly journals Stress Corrosion Analysis and Direct Cell Viability of Biodegradable Zn-Fe-Ca Alloy in In-Vitro Conditions

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 76
Author(s):  
Orit Avior ◽  
Noa Ben Ghedalia-Peled ◽  
Tomer Ron ◽  
Jeremy Goldman ◽  
Razi Vago ◽  
...  
Keyword(s):  
Cell Viability ◽  
Stress Corrosion ◽  
Alloy Surface ◽  
Biodegradable Implants ◽  
Biodegradable Implant ◽  
Cyclic Potentiodynamic Polarization ◽  
Direct Cell ◽  
Phosphate Buffered Saline ◽  
Zn Alloy

Due to the excellent biocompatibility of Zn and Zn-based alloys, researchers have shown great interest in developing biodegradable implants based on zinc. Furthermore, zinc is an essential component of many enzymes and proteins. The human body requires ~15 mg of Zn per day, and there is minimal concern for systemic toxicity from a small zinc-based cardiovascular implant, such as an arterial stent. However, biodegradable Zn-based implants have been shown to provoke local fibrous encapsulation reactions that may isolate the implant from its surrounding environment and interfere with implant function. The development of biodegradable implants made from Zn-Fe-Ca alloy was designed to overcome the problem of fibrous encapsulation. In a previous study made by the authors, the Zn-Fe-Ca system demonstrated a suitable corrosion rate that was higher than that of pure Zn and Zn-Fe alloy. The Zn-Fe-Ca system also showed adequate mechanical properties and a unique microstructure that contained a secondary Ca-reach phase. This has raised the promise that the tested alloy could serve as a biodegradable implant metal. The present study was conducted to further evaluate this promising Zn alloy. Here, we assessed the material’s corrosion performance in terms of cyclic potentiodynamic polarization analysis and stress corrosion behavior in terms of slow strain rate testing (SSRT). We also assessed the ability of cells to survive on the alloy surface by direct cell culture test. The results indicate that the alloy develops pitting corrosion, but not stress corrosion under phosphate-buffered saline (PBS) and air environment. The direct cell viability test demonstrates the successful adherence and growth of cells on the alloy surface.

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