Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application

Low density, biodegradable and non-toxicity magnesium (Mg) has received great attention as biodegradable medical implants as it does not require second surgical procedure to remove the implant. However, poor corrosion resistance, rapid degradation and hydrogen gas evolution in human body fluid have...

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Main Author:	Tok, Hong Yuan
Format:	Thesis
Language:	English
Published:	2015
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/81379/1/TokHongYuanMFKM2015.pdf
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spelling	my-utm-ep.813792019-08-23T04:06:56Z Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application 2015 Tok, Hong Yuan TJ Mechanical engineering and machinery Low density, biodegradable and non-toxicity magnesium (Mg) has received great attention as biodegradable medical implants as it does not require second surgical procedure to remove the implant. However, poor corrosion resistance, rapid degradation and hydrogen gas evolution in human body fluid have limited its clinical application. This research is aimed to investigate the effect of bismuth (Bi) on the microstructures and corrosion behavior of Mg based alloy. The first stage of the research was focused on the effect of Bi on the binary Mg-Ca alloy by the addition of Bi from 0.5 to 12wt.%. The same process was repeated in the second stage by replacing binary Mg–Ca alloy with ternary Mg–Ca–Zn alloy. Microstructural analysis was conducted by optical microscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The corrosion resistance was investigated by using in vitro immersion tests and electrochemical test in Kokubo simulated body fluid (SBF). The results show that the grain size decreased with addition of Bi contents in both Mg-Ca-xBi and Mg-Ca-Zn-xBi alloys. SEM micrograph shows that the amount of intermetallic phases increased with increasing of Bi content in both ternary and quaternary alloys. The addition of 0.5 wt.% Bi content was found to enhance the corrosion resistance of both Mg based alloys and produced the lowest dissolution rate. Further addition of Bi content up to 12wt.% have deteriorate the corrosion resistance. These results show that the Bi element would enhance the corrosion behavior of Mg based alloys when it is solutes inside the a-Mg matrix. The precipitation of the intermetallic phases was detrimental to the corrosion resistance. The overall results show that Mg–Ca–0.5Bi and Mg–Ca–Zn–0.5Bi alloys presented highest corrosion resistance hence it can be good candidates for biomedical implant applications. 2015 Thesis http://eprints.utm.my/id/eprint/81379/ http://eprints.utm.my/id/eprint/81379/1/TokHongYuanMFKM2015.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:120128 masters Universiti Teknologi Malaysia Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Tok, Hong Yuan Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application
description	Low density, biodegradable and non-toxicity magnesium (Mg) has received great attention as biodegradable medical implants as it does not require second surgical procedure to remove the implant. However, poor corrosion resistance, rapid degradation and hydrogen gas evolution in human body fluid have limited its clinical application. This research is aimed to investigate the effect of bismuth (Bi) on the microstructures and corrosion behavior of Mg based alloy. The first stage of the research was focused on the effect of Bi on the binary Mg-Ca alloy by the addition of Bi from 0.5 to 12wt.%. The same process was repeated in the second stage by replacing binary Mg–Ca alloy with ternary Mg–Ca–Zn alloy. Microstructural analysis was conducted by optical microscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The corrosion resistance was investigated by using in vitro immersion tests and electrochemical test in Kokubo simulated body fluid (SBF). The results show that the grain size decreased with addition of Bi contents in both Mg-Ca-xBi and Mg-Ca-Zn-xBi alloys. SEM micrograph shows that the amount of intermetallic phases increased with increasing of Bi content in both ternary and quaternary alloys. The addition of 0.5 wt.% Bi content was found to enhance the corrosion resistance of both Mg based alloys and produced the lowest dissolution rate. Further addition of Bi content up to 12wt.% have deteriorate the corrosion resistance. These results show that the Bi element would enhance the corrosion behavior of Mg based alloys when it is solutes inside the a-Mg matrix. The precipitation of the intermetallic phases was detrimental to the corrosion resistance. The overall results show that Mg–Ca–0.5Bi and Mg–Ca–Zn–0.5Bi alloys presented highest corrosion resistance hence it can be good candidates for biomedical implant applications.
format	Thesis
qualification_level	Master's degree
author	Tok, Hong Yuan
author_facet	Tok, Hong Yuan
author_sort	Tok, Hong Yuan
title	Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application
title_short	Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application
title_full	Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application
title_fullStr	Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application
title_full_unstemmed	Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application
title_sort	microstructures and corrosion behavior of biodegradable mg–ca–xbi and mg–ca–zn–xbi alloys for biomedical implant application
granting_institution	Universiti Teknologi Malaysia
granting_department	Mechanical Engineering
publishDate	2015
url	http://eprints.utm.my/id/eprint/81379/1/TokHongYuanMFKM2015.pdf
_version_	1747818317489373184

Microstructures and corrosion behavior of biodegradable Mg–Ca–xBi AND Mg–Ca–Zn–xBi alloys for biomedical implant application

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