Publication details

Authors: Jang, Yongseok; Tan, Zongqing; Jurey, Chris; Xu, Zhigang; Dong, Zhongyun; Collins, Boyce; Yun, Yeoheung; Sankar, Jagannathan 
Title: Understanding corrosion behavior of Mg-Zn-Ca alloys from subcutaneous mouse model: Effect of Zn element concentration and plasma electrolytic oxidation 
Type: Journal Article 
Publisher: Materials Science and Engineering: C 
Year: 2015 
Volume: 48 
Start Page: 28 
End Page: 40 
DOI: 10.1016/j.msec.2014.11.029 
Abstract: Mg-Zn-Ca alloys are considered as suitable biodegradable metallic implants because of their biocompatibility and proper physical properties. In this study, we investigated the effect of Zn concentration of MgxZn0.3Ca (x = 1, 3 and 5 wt.%) alloys and surface modification by plasma electrolytic oxidation (PEO) on corrosion behavior in in vivo environment in terms of microstructure, corrosion rate, types of corrosion, and corrosion product formation. Microstructure analysis of alloys and morphological characterization of corrosion products were conducted using x-ray computed tomography (micro-CT) and scanning electron microscopy (SEM). Elemental composition and crystal structure of corrosion products were determined using x-ray diffraction (XRD) and electron dispersive x-ray spectroscopy (EDX). The results show that 1) as-cast MgxZn0.3Ca alloys are composed of Mg matrix and a secondary phase of Ca2Mg6Zn3 formed along grain boundaries, 2) the corrosion rate of MgxZn0.3Ca alloys increases with increasing concentration of Zn in the alloy, 3) corrosion rates of alloys treated by PEO sample are decreased in in vivo environment, and 4) the corrosion products of these alloys after in vivo tests are identified as brucite (Mg(OH)2), hydroxyapatite (Ca10(PO4)6(OH)2), and magnesite (MgCO33H2O). 
Keywords: Biodegradation, Plasma electrolytic oxidation, MgZnCa alloy, Corrosion product, In vivo