Plasma Sprayed Hydroxyapatite Coatings with Nano-hydroxyapatite Prepared by Ultrasonic Precipitation Process

Nano-particle hydroxyapatite （HA） was prepared with a novel ultrasonic precipitation process and the as-prepared nanopowder was used to produce hydroxyapatite （HA） coatings on titanium substrate via plasma spraying. The phase and the microstructure of the coating were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. Results showed that spherical particles could be prepared by ultrasonic precipitation process; and a corresponding dense HA coating with molten surface and low-porosity cross-section structure was acquired. During the plasma spraying process, new phases of Ca3（PO4）2 and Ca2P2O7 were generated. After heat-treating at 800 ℃ for 1 h, the contents of Ca3（PO4）2 and Ca2P2O7 decreased while HA content increased. Tensile adhesion tests showed that the plasma sprayed coating prepared with the spherical nanoparticles exhibited high tensile bond strength.