Effect of nano-hydroxyapatite and dutycycle on the structure and corrosion performance of plasma electrolyte oxidation coatings in simulated body fluid on Ti–6Al–4 V

Abstract

The formation of titanium oxide coatings on Ti–6Al–4 V substrates by plasma electrolyte oxidation and the corrosion behavior of coatings in simulated body fluid were investigated. The effect of the addition of nano-hydroxyapatite particles to electrolyte and duty cycle of plasma electrolyte oxidation on the coating thickness and its surface morphology was studied. Phase structure and morphology of coated parts were studied using X-ray diffraction patterns and scanning electron microscopy. Wear and corrosion resistance were compared in coated and uncoated samples. Biocompatibility of coating was investigated using in vitro immersion in simulated body fluid. It was found that the plasma electrolyte oxidation forms dense and compact oxide coatings with slightly porous outer layers. Formation of apatite phase on the surface of coated samples was examined after immersion in simulated body fluid for two weeks. The corrosion resistance of plasma electrolyte oxidation coatings formed in electrolyte with high concentration of nano-hydroxyapatite and high duty cycle (60%) is better than the corrosion resistance of plasma electrolyte oxidation coatings formed in other electrolytes. Energy-dispersive spectroscopy results indicate the formation of a complete and preservative coating on Ti base materials.