Toward understanding in vivo corrosion: Influence of interfacial hydrogen gas build‐up on degradation of magnesium alloy implants

Abstract

Limited material transport, causing gas cavities formation, is commonly observed during the degradation of magnesium implants, yet its effects on corrosion are not understood. Herein, a bespoke cell was designed, allowing for the incorporation of an additional agarose layer above the corroding magnesium sample. This design replicates the limited material transport in vitro and enables us to understand its influence on corrosion of magnesium alloys. This work investigated the influence of varying thickness of agarose (0-0.9 mm) on the corrosion of Mg-Zn-Zr magnesium alloy maintained at 37 C in phosphate-buffered saline (PBS). The introduction of agarose slowed transport of material away from the corroding magnesium surface, including the evolved hydrogen forming a gas cavity. It has been found that an initial increase in the agarose thickness (or the reduction in material transport) of 0.3 mm leads to an increase in the corrosion rate of the magnesium alloy by 62%. However, with a further increase in agarose thickness from 0.3 to 0.9 mm, the corrosion rate decreases by 37%. This observation has been attributed to the accumulation of, and competition between, chloride and hydroxide ions near the alloy's surface. In the presence of materials barrier, hydrogen measurement is no longer a reliable method for the measurement of corrosion rates. This study underscores the importance of the consideration of limited material transport during the in vitro corrosion tests of biomedical implants.

Effect of Vacancy Defects and Hydroxyl on the Adsorption of Glycine on Mg(0001): A First-Principles Study

“…The initial reactions of biological magnesium (Mg) alloy materials in the physiological environment of the human body depend on their surface properties [1][2][3][4][5]. Surface modification is one of the most commonly used methods to regulate the interaction between biomaterials and internal tissues, improving the biocompatibility and corrosion resistance of Mg alloys [6][7][8][9][10][11][12].…”