Fabrication of Ti/HA composite and functionally graded implant by three-dimensional printing

The aim of this study is to evaluate the feasibility of fabricating titanium(Ti)/hydroxyapatite(HA) composite and functionally graded implant by three-dimensional printing (3DP) technology. Nano-scale Ti and HA powders were mixed at the ratio of 8:2 and prepared with water-soluble binder. The Ti/HA composite CAD model was designed to be in cylinder shape (25 mm in diameter, 20 mm in height) with the 100% bond area in each layer. The functionally graded implant was 25 mm in diameter and 10 mm in height with two segments. The upper segment was composed of 100% Ti in each layer, whereas the lower was composed of 80%Ti/20%HA. The composite and functionally graded implant were fabricated by 3DP and sintered at 1200°C under protective argon atmosphere. There occurred a chemical reaction between Ti and HA, in which new resultants of Ca3(PO4)2, CaTiO3, TiO2 and CaO were created. The sintered Ti/HA composite had the aperture size from 50 to 150 μm and the compressive strength of 184.3±27.1 MPa. The result of this study demonstrated that it was feasible to fabricate Ti/HA composite and functionally graded implant by 3DP technology. The microstructure and mechanical properties of Ti/HA composite and functionally graded implant were conductive to bone cell ingrowth, resulting in the wide application of this biocomposite.