Properties of hydroxyapatite layers used for implant coatings

Metallic materials such as titanium and titanium alloy generally show good mechanical properties but their biocompatibility is limited. In order to manufacture implants which combine improved mechanical properties of metallic material with biotolerance of ceramics, hydroxyapatite coatings are applied. In this paper, plasma sprayed coatings (deposited on titanium Ti–6Al– 4V ELI alloy) were analysed. The phase composition of hydroxyapatite (HA) coatings can be determined using a number of methods. The most commonly used are Joel 5400 scanning microscope, scratch test, X-ray diffraction and Raman. The increase of the zirconium and aluminium phase significantly affects the coating adhesion, estimated by the scratch test technique.