FORMATION OF HYDROXYAPATITE COATING ON PURE TITANIUM SUBSTRATES BY ION-BEAM DYNAMIC MIXING

A hydroxyapatite (HAp) coating was deposited onto pure Ti substrates using an ion beam dynamic mixing (IBDM) method. In this study, a high energy Ca+ ion beam of 50 keV was irradiated concurrently during evaporation of HAp vapor onto Ti substrates to deposit the HAp film. The structure, solubility in Hanks' solution and adhesive strength of the coatings were evaluated. The as-coated film was amorphous and was almost dissolved within 1 day in the solution. A thin Ca-P-Ti hydroxide complex layer, however, was formed on the substrate surface, indicating that the IBDM film might possess a 'self-repairing function.'' The crystallinity of the HAp film was improved by heat treatment at 873 K in air, and the film obtained was slightly soluble in the solution. The adhesive strength of the as-coated film was more than 59 MPa. The strength decreased to 41 MPa after the heat treatment, but even this value exceeds that obtained using conventional methods.