Influence of different chelating agents on corrosion performance of microstructured hydroxyapatite coatings on AZ91D magnesium alloy

Abstract

To improve the bioactivity and corrosion resistance of AZ91D magnesium alloy, hydroxyapatite (HAp) coatings with novel microstructured morphologies were prepared successfully on AZ91D substrates via a facile hydrothermal method. Different chelating agents including polyaspartic acid (PASP) and ethylenediaminetetraacetic acid (EDTA) were introduced to investigate their effects on the morphology and corrosion resistance of the coated magnesium alloys. The results revealed that the coating prepared with PASP was composed of many uniform urchin-like microspheres, while the coating prepared with EDTA consisted of many flower-like particles. Moreover, the crystallinity of the coating prepared with EDTA was much higher than that of the coating prepared with PASP. Electrochemical tests revealed that the corrosion resistance of the substrate was significantly improved after being coated with each coating. Immersion test of the coated samples in simulated body fluid (SBF) demonstrated that the coatings could be biodegraded gradually and induce the formation of calcium phosphate particles.

Keywords

magnesium alloy / hydroxyapatite coating / chelating agent / corrosion resistance

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