Chemical surface treatment on Titanium alloys for biomedical applications

<p dir="ltr">Titanium alloy Ti6Al4V is widely used for implants because of its strength and corrosion resistance, but its bioinert surface can limit bonding with bone. This study aimed to improve its bioactivity through hydrothermal and anodization treatments. Hydrothermal experiments showed that solution pH strongly influenced phase formation: HA(1) (pH ~4.2) produced hydroxyapatite and monetite, while HA(2) (pH ~7) formed only hydroxyapatite. Anodization in sulfuric acid created porous oxide layers, which supported further calcium phosphate deposition during hydrothermal treatment. Anodization in ethylene glycol with NH₄F produced TiO₂ nanotubes, with 40 minutes giving uniform honeycomb tubes about 1.3–1.5 μm thick. Longer times (110–180 minutes) caused the growth of a second oxide layer and reduced tube quality. High-voltage anodization (0.5 M H₂SO₄, 120 V, 6 min) formed porous oxides that were superhydrophilic (contact angle <10°) and promoted hydroxyapatite formation after 7 days in simulated body fluid. Among the methods, ethylene glycol anodization provided the most ordered nanotube structure, while hydrothermal treatment at neutral pH achieved the most stable hydroxyapatite layer. Together, these results demonstrate that controlled anodization and hydrothermal conditions can create bioactive coatings with improved roughness, wettability, and mineral deposition, offering strong potential for enhanced bone integration.</p>