Polycrystalline coating of hydroxyapatite on TiAl₆V₄ implant material grown at lower substrate temperatures by hydrothermal annealing after pulsed laser deposition

摘要

Hydroxyapatite (HA) is a bioactive ceramic material that mimics the mineral composition of natural bone. This material does not possess acceptable mechanical properties for use as a bulk biomaterial; however, it does demonstrate significant potential for use as a coating on metallic orthopaedic and dental prostheses. Pulsed laser deposition (PLD) of thin films of HA on TiAl₆V₄ have shown crystalline coatings to be obtained at temperatures of the order of 350–500 °C. This condition of high substrate temperature promoted the oxidation of the substrate surface prior to the growth of the HA layer and the oxidation layer degraded the adhesion of the coating to the substrate. In this study, thin films of HA were deposited on TiAl₆V₄ alloy at a lower temperature of 200 °C by PLD and crystallized by a hydrothermal treatment at 100 °C. The film was subjected to mechanical as well as cell viability tests in vitro. The thickness, roughness, crystallanity, composition ratio, adhesive strength, and cell adhesion of the film suggest the application of this technique for producing bioactive implants.