Biocorrosion evaluation and bonding strength of HA-CS/PLA hybrid coating on micro-arc oxidised AZ91D magnesium alloy

ABSTRACT

In order to improve the corrosion resistance and bonding strength of the micro-arc oxidised (MAO) AZ91D magnesium (Mg) alloy, the hydroxyapatite (HA)-chitosan (CS) and polylactic acid hybrid (PLA) coatings on MAO Mg alloy were fabricated via electrochemical co-deposition and dip-coating method. The influences of different concentrations of PLA on the phase composition, surface morphology, hydrophobic, bonding strength, and corrosion resistance were investigated. The surface morphology and immersion test in simulated body fluid (SBF) showed that the PLA coating could further seal the surface and prevent the HA-CS coating from cracking, thus improving the corrosion resistance of the sample. The sample with 20% PLA had the lowest corrosion current density (1.13 × 10⁻⁸ A/cm²) and the highest strength (18.84 N). These results manifest that the MAO/HA-CS/PLA is a protective coating on magnesium alloys for implants application.

KEYWORDS:

• Magnesium alloy
• micro-arc oxidation
• electrochemical co-deposition
• polylactic acid
• corrosion resistance

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Natural Science Foundation of Zhejiang Province [LY15E020010].