The effects of impurities on biodegradation behavior of pure magnesium in Hanks; solution

Abstract

Corrosion behavior of pure magnesium with different contents of impurities such as iron and manganese in Hanks` solution has been investigated in order to tailor the life time of biodegradable implant made of pure magnesium. Two distinct stages of corrosion were observed: slow corrosion rate stage and a subsequent fast corrosion rate stage. The first stage is characterized by uniform corrosion which produce magnesium hydroxide and calcium phosphate film on the magnesium surface, resulting in slow corrosion rate. The second stage with abrupt increase of corrosion rate was induced by iron precipitations and was stimulated with increase of the Fe/Mn ratio. This corrosion was developed to a preferred crystallographic pitting corrosion: pits propagated along preferred crystallographic plane and several layers of uncorroded Mg planes remained with narrow interplanar space. From this study, it is expected that the lifetime of biodegradable implant made of pure Mg can be tailored by controlling the amount and ratio of the impurities