The effects of sintering temperature on the physical properties of Ti-Nb-Sn with hydroxyapatite composites for biomaterial application / Wan Nurul Syaza Wan Nawai

Titanium (Ti) composites have been extensively used and rapidly progressed in the development of metallic medical instrumental and surgical implant for decades. Studies on Ti-35Nb-2.5Sn-15HA composite have been revealed to be a potential material for biomedical application. However, it only focuses on dense cortical bone structure with 10-20 GPa and used ball mill that are the main cause for contamination of mixing process in powder metallurgy. Hence, targeting on cancellous bone of basic requirement of 0.01 to 3 GPa with 30 to 80% porosity and to eliminate the contamination from ball milling were done through mixing with no ball mill via conventional powder metallurgy process. The fabrication of Ti-35Nb-2.5Sn-15HA composite was prepared by using 2 wt% stearic acid, mixing duration of 10 minutes, uni-axial compaction pressure of 111 MPa and heating rate of 10°C/min in a vacuum furnace. Varying sintering temperature was done at 900°C, 1000°C, 1100°C, 1200°C and 1300°C. The XRD analysis result shows new phases other than the element being developed in the composites after sintering. The peaks of the XRD patterns have been identified as belonging to the phases of β-Ti, TiO2, NbSn, NbO, CaTiO3 and CaNb2O6. Higher sintering temperatures promote better sintering in the sintered composite resulting in high densification, Vickers microhardness and compressive strength. The result indicated that optimum sintering temperatures of green compacts were found at 1000°C whereby at this sintering temperature produced better microstructure, physical and mechanical properties of the sintered composites with highest densification, lowest total porosity, Vickers microhardness, compressive strength and elastic modulus of 26.25%, 73.75%, 469.02 HV, 14.81 MPa and 1.48 GPa respectively. Bioactivity test was done by Kokubo method. From the FESEM observation, it shows that various precipitation shapes of CaP apatite formation grown were scattered from tiny to big globular furry like shape at the sample surface. From the EDX analysis, it is confirmed that the precipitation shapes on the sample surface consist of calcium and phosphorus rich phase, CaP. Due to these results, it indicates that Ti-35Nb-2.5Sn-15HA is a promising Ti composite for biomaterial application.