Evaluation of the Corrosion Resistance and Cytocompatibility of a Bioactive Micro-Arc Oxidation Coating on AZ31 Mg Alloy

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.

The Potential of Calcium/Phosphate Containing MAO Implanted in Bone Tissue Regeneration and Biological Characteristics

“…The SEM morphology of the Ca-P containing MAO samples with typical pancake-like structure (a cratered structure with a central pore), as shown in Figure 2 . Compare with our previous study [ 30 ], the Ca-P containing MAO samples showed a relatively uniform and smooth surface than the Ca-P-free MAO samples. Calcium phosphate had very low solubility in water [ 33 ] because the individual calcium cations and phosphate anions were tightly bonded to each other in an aqueous medium.…”

“…The plates were then ultrasonically cleaned in acetone, rinsed with deionized water and dried in a hot air stream of 60 °C. The process to prepare MAO coatings on the AZ31 magnesium surface was carried out on a pulse power generator (MIRDC) with work voltage up to 400 V, current up to 10 A, duty cycle at 20% and the electrical frequency at 4000 Hz for 30 min [ 30 ]. The water bath made of stainless steel has 45 L water capacity.…”

“…According to previous studies [ 30 ], it has successfully been designed a micro arc oxidation (MAO) coating with good anti-corrosion performance under pulsed bipolar DC current conditions in a Si- and P-containing electrolyte. The MAO treatment is applied by modifying the surface properties of AZ31 Mg alloy to improve the biocompatibility of the test material in rabbit implant application.…”

Effects of Ti, Ni, and Dual Ti/Ni Plasma Immersion Ion Implantation on the Corrosion and Wear Properties of Magnesium Alloy

“…Magnesium alloys are widely used in many fields because of their light weight, good damping capacity, and recycling potential [1][2][3]. Unfortunately, the corrosion resistance of magnesium alloys in many engineering applications is insufficient [4,5] and methods such as micro-arc oxidation [6,7], laser cladding [8,9], plasma electrolytic oxidation [10,11] and ion implantation [12][13][14][15] have been proposed to improve the corrosion properties. For example, Zn [16,17], Zr [18], Nd [19], C 2 H 2 [20] and Si [21] ion implantations have been conducted on Mg alloys to improve the surface properties [17,22].…”

Corrosion Behavior and Mechanism of Carbon Ion-Implanted Magnesium Alloy

“…However, the corrosion resistance of magnesium alloys is not good enough [6,7]. To date, many methods have been carried out to improve the corrosion properties of magnesium alloys such as microarc oxidation [8,9], laser cladding [10,11], and ion implantation [12][13][14][15][16]. Ion implantation causes the substrate and coating have a good binding force compared to other methods.…”