Interfacial characteristic of graded hydroxyapatite and titanium thin film by magnetron sputtering

Graded film of calcium phosphate and titanium (Ti) was prepared on Ti-6Al-4V alloy by radio-frequency magnetron sputtering. Concurrent sputtering of HA and Ti for four times, The area proportions of HA to Ti in the targets are 20%, 50%, 90% and 100% respectively, contributes a gradual distribution of Ca, P, O and Ti across the interface of film and alloy substrate. The graded HA/Ti film is formed by annealing for 1 h at 600 °C water vapour flow. The tensile adhesion strength of graded sputtered and annealed HA/Ti film is approximately 35 Mpa, which is an obvious advantage compared with monolithic HA film. The results obtained from the nanoindentation test show that Youngʹs modulus and microhardness of graded HA/Ti film are also graded distribution and strain reversion was much better than that in the monolithic HA film.