Corrosion Properties of Biodegradable AZ31 and ZK60 Magnesium Alloys: In Situ Study ^†

Abstract

Biodegradable magnesium alloys are promising materials for application in medicine. The corrosion rate and type of corrosion are among the most important properties for this kind of materials. The fine-grained biodegradable alloys AZ31 (hot-rolled) and ZK60 (extruded) were studied in the present work with the use of in situ methods including the hydrogen evolution corrosion rate measurement and real-time surface observation as well as ex situ methods such as the weight loss assessment and the post-mortem examination by confocal laser scanning microscopy. The experimental methods included immersion test in SBF (0.9% NaCl aqueous solution) during 120 h with 37 °C with recirculating corrosion media. The hydrogen evolution was measured with a burette with a constant time interval of 1 hour. The real-time surface observation was carried out with a high-resolution camera. The measurement of pH level was done twice a day. Corrosion rate curves, 3D morphology of corroded morphology and video recordings showing evolution of corrosion damage have been obtained. As a result, ZK60 was found to be less corrosion-resistant and addicted to pitting corrosion, whereas AZ31 showed pronounced susceptibility to filiform corrosion.