In-vitro study on apatite/titanium composite coatings with supersonic free-jet PVD

Hydroxyapatite (HAp) has many applications in the medical fi eld. The objective of this study is to produce HAp/Ti composite coating with Supersonic Free-Jet PVD (SFJ-PVD). The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas fl ow and to form a thick coating fi lm. In a gas evaporation chamber, a source material is evaporated to form nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a deposition chamber with an inert gas fl ow through a transfer pipe. The gas fl ow is generated by the pressure difference between the chambers and accelerated to the supersonic fl ow of 4.2 Mach through a specially designed supersonic nozzle. With SFJ-PVD, we obtain a uniform high-density HAp/Ti composite coating. XRD analysis reveals that the composite coating is composed of Ti and HAp. An in vitro study was carried out to investigate the bioactivity of the HAp/Ti composite coating under simulated body fl uid.