Hwang, Li-Fu
(2019)
Bio-corrosion studies of biodegradable alloys in the Mg-Y-Sr and Mg-Zn-Sr system.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Pure magnesium possesses similar mechanical properties compared to natural human bone, which helps to avoid the negative effects of stress shielding induced typically by other high modulus bio-inert metallic implants. Magnesium is also considered a biodegradable metal, its degradation in-vivo aids in bone regeneration and reduces the need for implant removal surgeries. However, controlling the corrosion rate and reduction of the biotoxicity are the important goals for optimizing Mg alloys for implant application. In this study, Mg-Zn-Sr and Mg-Y-Sr alloys were researched as biodegradable biomedical materials. Zn and Sr are useful alloying elements for refining the grains in Mg alloys. Y serves as an effective solid solution hardener, arising from the large difference in atomic radii between Mg and Y atoms. The two alloys were received our collaborator in India following synthesis using melting followed by squeeze casting. The results of x-ray diffraction patterns and scanning electron microscopy were used to understand the microstructural/composition-functional relationship of the Mg-Zn-Sr and Mg-Y-Sr alloy system. A higher amount of strontium leads to the formation of a secondary Mg17Sr2 phase along the grain boundaries. The corrosion properties of these alloys were analyzed in-vitro by immersion and electrochemical tests. The electrochemical corrosion results demonstrated that incorporation of 1 wt% Sr lead to a decrease in corrosion current (Icorr) and corrosion rates as compared to pure Mg. Further addition of Sr to the Mg-Zn-Sr and Mg-Y-Sr alloys lead to an increase in corrosion rate due to the presence of higher amounts of secondary phase precipitates. The biomechanical properties and in-vitro cell-toxicities of these alloys should be evaluated in future for their possible applications as a bone fixation device and bone graft.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
27 June 2019 |
| Date Type: |
Publication |
| Defense Date: |
1 April 2019 |
| Approval Date: |
27 June 2019 |
| Submission Date: |
30 March 2019 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Number of Pages: |
68 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering and Materials Science |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Microstructure, Corrosion test,Biomaterials |
| Date Deposited: |
27 Jun 2019 15:59 |
| Last Modified: |
27 Jun 2019 15:59 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/36177 |
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