Bioactive Ca-P coating with self-sealing structure on pure magnesium

Area of Science:

• Biomaterials Engineering
• Surface Science
• Materials Science

Background:

• Pure magnesium's poor corrosion resistance limits its biomedical applications.
• Developing protective coatings is crucial for magnesium-based implants.
• Bioactive coatings can promote osseointegration and reduce inflammatory responses.

Purpose of the Study:

• To fabricate bioactive coatings containing Ca and P with self-sealing structures on pure magnesium via micro-arc oxidation (MAO).
• To investigate the effects of different applied voltages on coating morphology, composition, corrosion resistance, and degradation behavior in Hank's solution.
• To evaluate the potential of these MAO coatings for biomedical applications.

Main Methods:

• Micro-arc oxidation (MAO) technique was employed using a calcium hydroxide-based electrolyte.
• Coatings were prepared at three different applied voltages: 360 V, 410 V, and 450 V.
• Morphology, chemical composition (EDX), electrochemical corrosion tests, and long-term immersion tests in Hank's solution were performed.

Main Results:

• MAO coatings exhibited similar morphologies with micro-pores filled by compound particles, containing O, Mg, F, Ca, and P.
• All coatings significantly enhanced corrosion resistance compared to pure magnesium.
• The coating produced at 450 V showed superior corrosion resistance due to greater thickness.
• MAO coatings demonstrated mild and uniform degradation, with Ca and P elements detected on surfaces after immersion.
• Immersion tests confirmed reduced corrosion rates and maintained lower pH levels for coated samples.

Conclusions:

• MAO coatings with bioactive Ca and P elements and self-sealing structures effectively enhance the corrosion resistance of magnesium.
• The developed coatings show promising potential for biomedical applications, particularly for biodegradable implants.
• Optimizing MAO parameters, such as applied voltage, can further tailor coating properties for specific medical uses.