Laser Surface Modification for Rapid Oxide Layer Formation on Ti-6Al-4V

The study compares and analyses the properties of the oxide layers formed on the Ti-6Al-4V surfaces treated with laser and general furnace annealing processes. The titanium alloy was subjected to different temperatures or laser powers and then immersed in the modified artificial simulated body fluid (m-SBF) solution for up to 7 days to evaluate for bioactivity. The results show that the surface of the samples exhibit different color appearances after annealing at raised temperatures or laser powers due to the different oxide layer thicknesses and phases. When the temperature and laser power were increased, the contact angle of the annealed sample would decrease gradually. Furthermore, a layer of hydroxyapatite-rich bone-like apatite was found on the surfaces of annealed samples after immersing them in the m-SBF solution for a period of time. This bone-like apatite layer can be rapidly grown on the laser annealing specimens when immersed in an m-SBF solution for only 3 days, indicating its excellent bioactivity.