National Projects
Stress corrosion of magnesium alloys intended for biodegradable implants in physiological environments containing hydrogen
Title:
Stress corrosion of magnesium alloys intended for biodegradable implants in physiological environments containing hydrogen
Programme name: Preludium
Co-financing for Łukasiewicz – GIT: PLN 164,240.00
Total value of the project: PLN 194,740.00
Start: 07.02.2022 / End: 06.02.2025
Executive Agency: National Science Centre
Project Manager:
Adam Gryc, BEng, MSc
Tel.: 32 2345 269
E-mail: adam.gryc@git.lukasiewicz.gov.pl
Objective:
In recent years, magnesium alloys have gained importance not only as lightweight construction materials, but also as promising biomaterials used for implants. Magnesium-based biomaterials are the subject of intensive research in terms of biocompatibility, cytotoxicity and the development of new alloys, as well as their destruction processes, the better understanding of which leads to the design of biodegradable materials for implants. However, the current state of knowledge about some of their corrosion processes, in particular hydrogen-assisted stress corrosion, is still insufficient and unsystematic. At the same time, hydrogen, which is the product of the reaction between magnesium alloys and aqueous solutions, has a significant impact on the strength properties of magnesium alloys, leading to their reduction, which in turn may cause unexpected damage to the implant, subjected to loads much less than the assumed strength of the material.
The main objective of the project is to identify phenomena and mechanisms occurring during hydrogen-assisted stress corrosion of selected magnesium alloys, used for biodegradable implants in the environment of physiological fluids, and to determine the role of chemical composition and microstructure in the mentioned processes and mechanisms.
The project will allow to verify and systematise the current state of knowledge on hydrogen-assisted stress corrosion of selected magnesium alloys for biomedical applications from three groups:
- alloys containing rare earth elements (WE43),
- alloys free of rare earth elements (ZX50)
- and amorphous alloys (Mg Am35).
Rare earth elements have a negative impact on the human body, hence special attention is paid to the development of new alloys that do not contain these elements, such as the ZX50 alloy. In turn, amorphous alloys are characterised by very high strength and corrosion resistance, which makes them promising candidates for further applications in medicine. However, they require further research, also in the area of hydrogen-assisted corrosion.
The test material will be varied both in terms of chemical composition and microstructure – the tested alloys will be subjected to processing using the modern large KoBo plastic deformation method, and the degradation of their strength properties will be assessed under conditions of constant strain (SSRT) and low-cycle fatigue under mechanical loads in the environment of physiological fluids containing hydrogen and in the presence of selected bacteria. This comprehensive research method will allow to simulate the actual operating conditions of these materials and help to better understand the processes of their destruction in an environment containing hydrogen. Hydrogen content tests and microstructure analysis will allow to determine the role of hydrogen in reducing mechanical properties and premature cracking of the tested materials. It is also planned to investigate changes in the content of ions in the corrosive environment, reflecting the emission of individual elements to the human body during gradual decomposition of implants.
The planned research should allow to identify the phenomena and mechanisms of stress corrosion and hydrogen-assisted degradation processes in the environment of synthetic physiological fluids, with particular emphasis on the modern ZX50 alloy and Mg Am35 amorphous metallic glass. The impact of chemical composition and microstructure on hydrogen-assisted destruction will also be determined and ways of protection against this phenomenon will be proposed.
In practical terms, the research planned in the project will allow to verify the potential of structural changes of large plastic deformations caused by the KoBo method as one of the possibilities of protection against the negative impact of hydrogen by increasing the plastic properties of the tested alloys.
