**8. Conclusions**

**Figure 7.** Morphology of HA-SiO2 coated Ti14Nb4Sn alloy

38 Titanium Alloys - Advances in Properties Control

composition of hydroxyapatite during the deposition process.

**Figure 8.** XRD patterns of HA-SiO2 coatings on Ti14Nb4Sn alloy

The XRD pattern of the HA-SiO2 coated titanium alloys is shown in Figure 8. The identified phases were hydroxyapatite, CaO.SiO2.TiO2, calcium pyrophosphate, CaTiO3 and titanium. After annealing, the crystalline phase of HA was present at 2*θ* = 30° which matches the (107) plane. A peak corresponding to CaO.SiO2.TiO2 phase was also observed at 43.5° and in‐ dexed as (223). In addition, the peak confirms the presence of the silica phase. The phase CaO, *i.e.,* in CaO.SiO2.TiO2 observed in the XRD pattern could be related to the partial de‐ This chapter describes the importance of developing a bioactive titanium alloy scaffold for bone tissue engineering applications. Ti14Nb4Sn alloy was designed and then fabricated us‐ ing powder metallurgy method. The porosity ranged from 55 to 80% with pore sizes of 100-600 µm.

Powder metallurgy that employed the space-holder sintering method was successful in fabricating samples for biomedical implant studies. The method produced porous struc‐ tures that (i) enable better fixation, (ii) lower elastic modulus to match the properties of natural bone, and (iii) construct morphologies that mimic the features of natural bone structures.

To further enhance the biocompatibility of titanium alloys, 2 µm thick hydroxyapatite and 200 nm thick SiO2 coatings were deposited onto Ti alloys using e-beam evaporation and RF magnetron sputtering. SEM images showed that the microstructure of the hydroxyapatite coating is homogenous, with some cracks appearing on its surface. XRD results confirmed that the coatings consisted of an HA phase with some CaO.SiO2.TiO2, CaTiO3 and phases. Silica was also present in the XRD spectrum, which corresponds to the CaO.SiO2.TiO2 phase. It was demonstrated that the e-beam evaporation and magnetron sputtering methods are suitable for depositing silica and hydroxyapatite coatings. The hydroxyapatite-silica config‐ uration may be useful for biomedical implants, as it provides better adhesion strength for rapid osseointegration acceleration. Further study will focus on the biological response of these coatings.

### **Acknowledgements**

CW acknowledges the financial support from the Australian Research Council (ARC) through the ARC Discovery Project DP110101974.
