Effects of Alloying Element Ca on the Corrosion Behavior and Bioactivity of Anodic Films Formed on AM60 Mg Alloys.

Anawati Anawati,Hidetaka Asoh,Sachiko Ono

doi:10.3390/ma10010011

Abstract

Effects of alloying element Ca on the corrosion behavior and bioactivity of films formed by plasma electrolytic oxidation (PEO) on AM60 alloys were investigated. The corrosion behavior was studied by conducting electrochemical tests in 0.9% NaCl solution while the bioactivity was evaluated by soaking the specimens in simulated body fluid (SBF). Under identical anodization conditions, the PEO film thicknesses increased with increasing Ca content in the alloys, which enhanced the corrosion resistance in NaCl solution. Thicker apatite layers grew on the PEO films of Ca-containing alloys because Ca was incorporated into the PEO film and because Ca was present in the alloys. Improvement of corrosion resistance and bioactivity of the PEO-coated AM60 by alloying with Ca may be beneficial for biodegradable implant applications.

Highlights

Magnesium (Mg) and its alloys are suitable candidates for biodegradable implants because of their high strength-to-weight ratio, appropriate mechanical properties (e.g., Young’s modulus), and excellent biocompatibility in human body fluids [1,2,3]
The effect of Ca on the corrosion behavior and bioactivity of plasma electrolytic oxidation (PEO) films formed on AM60 alloys containing 0, 1, and 2 wt % Ca was investigated; our conclusions are as follows: 1
The addition of Ca to the alloys slightly increased the PEO film thickness formed on AM60 alloys when constant-current anodization was performed

Summary

Introduction

Magnesium (Mg) and its alloys are suitable candidates for biodegradable implants because of their high strength-to-weight ratio, appropriate mechanical properties (e.g., Young’s modulus), and excellent biocompatibility in human body fluids [1,2,3]. Two methods are used to improve the corrosion resistance of Mg: an intrinsic approach involving the combination of a proper material processing method, the selection of appropriate alloying elements, and control of the microstructure; and an extrinsic approach involving surface treatments (e.g., anodization and coating) [4]. The addition of Ca as an alloying element tends to refine the metal grains of Mg alloys [5,6,7,8] and reduce the number of intermetallic (Mg17 Al12 ) grains formed [9,10,11,12], which improves the alloy’s corrosion resistance

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