Abstract
Magnesium alloys have recently been attracting attention as a degradable biomaterial. They have advantages including non-toxicity, biocompatibility, and biodegradability. To develop magnesium alloys into biodegradable medical materials, previous research has quantitatively analyzed magnesium alloy corrosion by focusing on the overall changes in the alloy. Therefore, the objective of this study is to develop a bioactive material by applying a ceramic oxide coating (magnesia) on AZ31 magnesium alloy through micro-arc oxidation (MAO) process. This MAO process is conducted under pulsed bipolar constant current conditions in a Si- and P-containing electrolyte and the optimal processing parameters in corrosion protection are obtained by the Taguchi method to design a coating with good anti-corrosion performance. The negative duty cycle and treatment time are two deciding factors of the coating’s capability in corrosion protection. Microstructure characterizations are investigated by means of SEM and XRD. The simulation body-fluid solution is utilized for testing the corrosion resistance with the potentiodynamic polarization and the electrochemical impedance test data. Finally, an in vivo testing shows that the MAO-coated AZ31 has good cytocompatibility and anticorrosive properties.
Highlights
Metallic materials are widely used as biomaterials for applications in the field of orthopedics due to their high mechanical strength and fracture toughness
Despite the objective function being a lower-the-better type of control function, the optimal level of the process parameters is the level with the highest S/N ratio
Our results showed that the adhesion of the samples could all be classified as 5B according to the ASTM D3359-17 [32] standard, indicating micro-arc oxidation (MAO) is a promising surface treatment technology on magnesium alloys which provides good adhesion strength
Summary
Metallic materials are widely used as biomaterials for applications in the field of orthopedics due to their high mechanical strength and fracture toughness. The implant is usually in contact with the body fluids that typically have a high ionic intensity. It tends to induce the Coatings 2019, 9, 396; doi:10.3390/coatings9060396 www.mdpi.com/journal/coatings. Ti-based alloys have been considered once as the most promising metals for biomaterial applications due to their light weight, bio-inertness, and good corrosion resistance in the early 1970s [7]. They are relatively poor in long-term tribological behaviors. Magnesium (Mg) and its alloys are emerging as the potential metallic materials for orthopedics due to their biodegradability in physiological body environment [5,10], excellent biocompatibility, and osteopromotion [5,11,12]
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