Hydroxyapatite thin films growth by pulsed laser deposition: effects of the Ti alloys substrate passivation on the film properties by the insertion of a TiN buffer layer

摘要

Hydroxyapatite (HA), Ca_5(PO_4)_3OH, is now widely used in stomatology and orthopedic surgery. Due to a good biocompatibility combined favorable bioactivity make as HA to be considered as a challenge to successful bone repair. We grow HA thin films on Ti-5Al-2.5Fe alloy substrate by pulsed laser deposition (PLD) technique. The films were deposited in vacuum at room temperature using a KrF excimer laser (λ = 248 nm, τ_(FWHM) ≥ 20 ns). After deposition the HA films were annealed at 550 °C in ambient air. The insertion of a bioinert TiN buffer layer at the HA film-metallic substrate interface was studied in terms of HA film microstructure and mechanical properties. SEM, TEM and SAED analysis structurally characterized films. The mechanical properties were evaluated by nanoindentation tests in static and scratch modes. Films with TiN interlayer contain uniquely crystalline HA phase and present better mechanical characteristics as compared with those deposited directly on Ti-alloy substrate.