Impact of sintering time on corrosion rate and relative density of titanium, titanium-aluminum alloy, and titanium-based composites for bio-applications

The corrosion of implanted metals in the human body results in degradation and the release of harmful ions. Titanium and its alloys are used in biomedical applications due to their corrosion resistance and biocompatibility. This study examines how the amount of time spent sintering affects the density and corrosion resistance of Ti, Ti-6% Al, and Ti-6 % Al-2% HA (hydroxyapatite). Al was incorporated into Ti to reduce its density and enhance corrosion resistance. In contrast, HA was added at 2%, which aims to improve bioactivity and facilitate better integration with bone tissue. The samples were fabricated through powder metallurgy by mixing for 4 hours, and the compaction was 550 MPa. We sintered all samples at 1,300 °C, with varying sintering times of 60, 90, and 120 minutes. The results indicated that samples sintered for 120 minutes exhibited the highest relative densities: 91.55% for Ti, 92.89% for Ti-6%Al, and 93.24% for Ti-6%Al-2%HA. These samples demonstrated the lowest corrosion rates, with 0.2075 mpy for Ti, 0.01199 mpy for Ti-6%Al, and 0.003129 mpy for Ti-6%Al-2%HA. X-ray diffraction analysis of the Ti-6%Al-2%HA sample revealed patterns that corresponded to the titanium alloy and its byproducts, which included Ti, CaTi₄P₆O₂₄, TiP₂O₇, TiO₂, and CaTiO₃. Atomic absorption spectroscopy analysis found that only a small amount of titanium ions (0.912 ppm) was released, and no aluminum ions were detected over 14 days. Additionally, the MTT assay demonstrated 85.3% cell viability. These findings suggest that Ti-6%Al-2%HA alloys have potential applications in biomedical implants due to their improved corrosion resistance and biocompatibility.