title: Understanding corrosion behavior of Mg-Zn-Ca alloys from subcutaneous mouse model: effect of Zn element concentration and plasma electrolytic oxidation.
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 Mg-xZn-0.3Ca (x=1, 3 and 5wt.%) 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 Mg-xZn-0.3Ca alloys are composed of Mg matrix and a secondary phase of Ca2Mg6Zn3 formed along grain boundaries, 2) the corrosion rate of Mg-xZn-0.3Ca 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 (MgCO3·3H2O).
authors.affiliation: Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A & T State University, Greensboro, NC 27411, USA.
authors.forename: Yongseok
authors.initials: Y
authors.lastname: Jang
authors.affiliation: Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, OH 45221, USA.
authors.forename: Zongqing
authors.initials: Z
authors.lastname: Tan
authors.affiliation: Luke Engineering, Wadsworth, OH 44282, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Jurey
authors.affiliation: Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A & T State University, Greensboro, NC 27411, USA.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Department of Internal Medicine, College of Medicine, University of Cincinnati, Cincinnati, OH 45221, USA.
authors.forename: Zhongyun
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A & T State University, Greensboro, NC 27411, USA.
authors.forename: Boyce
authors.initials: B
authors.lastname: Collins
authors.affiliation: Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A & T State University, Greensboro, NC 27411, USA. Electronic address: yyun@ncat.edu.
authors.forename: Yeoheung
authors.initials: Y
authors.lastname: Yun
authors.affiliation: Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A & T State University, Greensboro, NC 27411, USA.
authors.forename: Jagannathan
authors.initials: J
authors.lastname: Sankar
mesh_terms: D020341:Absorbable Implants; D000497:Alloys / Q000737:chemistry*; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000493:pharmacokinetics; D002118:Calcium / Q000737:chemistry; D003343:Corrosion; D004573:Electrolytes; D008274:Magnesium / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods*; D051379:Mice; D010084:Oxidation-Reduction; D040521:Subcutaneous Tissue; D014057:Tomography, X-Ray Computed; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry*
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D004573:Electrolytes; D008274:Magnesium; D015032:Zinc; D002118:Calcium
keywords: Biodegradation; Corrosion product; In vivo; Mg–Zn–Ca alloy; Plasma electrolytic oxidation