Fabrication and characterization of nanostructured hydroxyapatite coating on Mg-based alloy by high-velocity oxygen fuel spraying

Abstract

Magnesium alloys are currently being investigated in orthopedic applications due to their biodegradability and mechanical properties. However, sometimes these benefits are limited by their high corrosion rate in the physiological environment before healing of damaged bones. A large number of recent researches in this field have been dedicated to the control of magnesium corrosion rate by surface protection using new and advanced coatings. In this work, hydroxyapatite powders were coated on the anodized Mg-based alloy substrates by using high velocity oxy-fuel (HVOF) spraying. Increasing of the bioactivity and reduction of the released hydrogen gas during corrosion of the substrate were two main objects of this work. Phase formations were characterized by X-ray diffraction (XRD). It was found that around 96% of the phases formed were hydroxyapatite. The amounts of hydrogen gas released during magnesium corrosion tests in the simulated body fluid (SBF) were measured to evaluate the corrosion resistance of the coated samples. Hydroxyapatite (HA) coating reduced the hydrogen evolution from 100 per cm2 ml to about 15 per cm2 ml after 29 h of immersion.