| 초록 |
Development of biodegradable implants has received considerable attention in recent years and among them magnesium and its alloys assume significance. However, rapid corrosion, generation of a large volume of hydrogen gas, accumulation of hydrogen bubbles in gas pockets adjacent to the implant, increase in local pH of the body fluid are the major impediments in using then reducing the rate of corrosion of Mg is the most appropriate strategy. Among the various surface modification processes, microarc oxidation (MAO) appears to be promising. However, the presence of a higher pore density on the surface of the MAO coatings would facilitate quicker infiltration of the corrosive medium into the inner regions of the coating and subsequently down to the substrate, thus deteriorating the corrosion resistance of the coating by changing its local pH. In this perspective, the present study aims to address the development of MgO-Mg2SiO4-Al2O3 composite coatings by MAO using an alkaline silicate electrolyte modified with the addition of K3AlF6. The concentration of K3AlF6, deposition voltage and treatment time were varies to prepare composite coatings with varying compositions. The morphological features of the coatings were characterized by scanning electron microscopy (SEM) while their structural characteristics were evaluated by X-ray diffraction measurements. Corrosion resistance of the coatings in Hank’s balanced salt solution (HBSS) was evaluated by potentiodynamic polarization studies. The findings of the study reveal that addition of K3AlF6 in the alkaline silicate electrolyte has enabled the development of MgO-Mg2SiO4-Al2O3 composite coatings, which offer a better corrosion resistance of magnesium in Hank’s solution, suggesting their suitability for biomedical applications. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (No. 2011-0028709, 2013R1A1A2012322 & 2014R1A4A1005309). |
